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, Available online ,
doi: 10.11884/HPLPB202638.250460
Abstract:
Background Purpose Methods Results Conclusions
Reverse blocking diode thyristors (RBDTs) are attractive solid-state switches for pulsed power systems because of their high blocking capability and high di/dt turn-on potential. In practical DSRD-triggered operation, the rising-edge voltage slew rate (dv/dt) of the trigger pulse is a key waveform parameter that can alter the initial carrier injection and regenerative turn-on process, and therefore affects the switching transient and current build-up.
This work aims to quantify how the output dv/dt of a silicon-based drift step recovery diode (Si DSRD) influences the turn-on characteristics of an RBDT, and to identify the dv/dt range where further increase brings diminishing improvement under a fixed pulsed power circuit configuration.
A numerical analysis model of an Si DSRD-triggered RBDT was established by combining TCAD device simulation with an equivalent external circuit. In the simulations, the trigger pulse parameters other than the rising-edge dv/dt were kept constant to isolate the dv/dt effect, and the RBDT turn-on delay time, current rise time, and peak current were evaluated for multiple dv/dt conditions. An Si DSRD-based trigger circuit was then built for experimental verification. Different dv/dt levels were obtained by adjusting trigger-circuit parameters (including the pulse transformer core and turns as well as the shaping capacitor), and the trigger voltage across the RBDT and the corresponding current waveforms were measured to extract the same turn-on metrics.
Both simulation and experiment show that increasing the Si DSRD output dv/dt shortens the RBDT turn-on delay time and current rise time, while the peak current exhibits a slight increase under the tested circuit parameters. When dv/dt is raised beyond a certain range, the reductions in delay and rise time become progressively smaller and tend to saturate, indicating diminishing sensitivity of the turn-on transient to further dv/dt enhancement. The overall trends obtained from TCAD and measurements are consistent across the investigated dv/dt range.
The voltage rise rate of the Si DSRD trigger waveform is an effective control parameter for tailoring the RBDT turn-on transient, mainly reflected in reduced delay and faster current build-up, with a saturation tendency at higher dv/dt. The reported TCAD–experiment comparison provides a practical basis for selecting dv/dt levels and designing Si DSRD-based trigger conditions for RBDT switching in pulsed power applications.
, Available online ,
doi: 10.11884/HPLPB202638.250446
Abstract:
Background Purpose Methods Results Conclusions
Vacuum breakdown under intense electromagnetic fields in Relativistic Backward Wave Oscillator (RBWO) critically compromise the reliability of high power microwave sources. To meet increasingly demanding power capacity requirments, it is essential to further enhance the performances of resistance to vacuum breakdown. The processes of lectron emission and electron beam bombardment are closely associated with the physical interactions at the material surface. Furthermore, studies have indicated that refining the grain size of titanium suifaces may significantly increase their ability to withstand intense electromagnetic field-induced vacuum breakdown.
Given that surface self-nanocrystallization is a highly effective approach for improving the mechanical properties of metallic materials, particularly through grain fefinement at the nanometer scale, this article proposes a novel strategy utilizing surface self-nanocrystallization technology to suppress vacuum breakdown in RBWO under intense electromagnetic fields. Experimental validation was conducted to evaluate the effectiveness of this method in inhibiting vacuum breakdown under such extreme conditions.
This paper employs commercially pure titanium (TA2) as the research object, utilizing ultrasonic peening (USP) and microshot peening (MSP) as two distinct nanoparticle surface processing techniques. The nanostructural effects were characterized through scanning electron microscopy coupled with X-ray diffraction analysis. Subsequently, field emission testing apparatus and an X-band RBWO were employed to conduct comparatice experiments on field electron emission characteristics and vacuum breakdown performance high power microwave generation, respectively.
USP produces a gradient nanocrystalline layer extending 2-3 μm beneath the surface, with grain size refined to approximately 40 nm. MSP generates a more extensive gradient nanocrystalline layer reaching 30 μm in depth, with surface grains refined to about 48 nm. After undergoing MSP and USP treatment, TA2 exhibits a sequential reduction in the field emission current under the identical electric field, the tail erosion in the output microwave waveforms vanishes, and damage in the high-field region of the slow wave structure is mitigated.
The results demonstrate that both MSP and USP treatments successfully refine the surface grain size of TA2 to the nanoscale range of several tens of nanometers, forming a gradient nanostructured layer. Such surface self-nanocrystallization effectively suppresses field-induced electron emission and vacuum breakdown under intense electromagnetic fields. Notably, the USP treatment exhibits particularly pronounced inhibitory effects. This methodology provides technical support for further enhancing the power capacity of high power microwave generators based on RBWO.
, Available online ,
doi: 10.11884/HPLPB202638.250366
Abstract:
Background Purpose Methods Results Conclusions
The compensated pulsed alternator (CPA) is a pulsed power source that integrates rotor inertial energy storage, electromechanical energy conversion and power regulation. It connects the prime mover and the electromagnetic launch load directly as a “unit component”, reducing many intermediate links. It has the advantages of high output voltage, high power density, high frequency of repetition and long service life, and is regarded as the most promising pulsed power source for electromagnetic launch systems.
The air-core CPA (ACCPA) overcomes the limitations of ferromagnetic material saturation on magnetic field strength and rotational speed, significantly improving the motor’s energy storage density and power density. The Halbach permanent magnet array (HPMA) possesses a magnetic shielding, eliminating the need for a rotor core while generating an air-gap magnetic flux density (AGMFD) waveform with good sinusoidal characteristics. Therefore, this paper investigates the application of a double-layer HPMA rotor, which is simple in structure, strong in integrity, and easy to optimize, in the topological structure of ACCPA.
Without considering magnetic saturation, an analytical calculation model for the no-load electromagnetic field in an ACCPA was established using the subdomain model method in polar coordinates. Starting from the basic theory of electromagnetic fields, this method used the vector magnetic potential method to establish Laplace’s equations (for no- curl fields) or Poisson’s equations (for curl fields) for four subdomains respectively. By combining the boundary conditions between adjacent subdomains, the equations were solved jointly to obtain the mathematical expression for the no-load AGMFD of the motor, and the distribution of the no-load AGMFD was analyzed.
This analytical model could directly reflect the relationship between the no-load AGMFD distribution of the motor and its design parameters. The analytical model’s calculation results were highly consistent with the results of finite element analysis, verifying the accuracy of the analytical model. Its calculation results could relatively accurately reflect the static and steady-state performance of the motor.
The relationship between the four main parameters of the motor and the amplitude and sinusoidal characteristics of the radial and tangential components of the no-load AGMFD is studied, which can provide technical support for the subsequent optimization of the motor’s no-load air-gap magnetic field and further calculation design.
, Available online ,
doi: 10.11884/HPLPB202638.250454
Abstract:
Background Purpose Methods Results Conclusions
To address the challenge of achieving central fueling in future fusion reactors, this study carried out fueling experiments on the Compact Torus (CT) injection system based on pulse high-power technology. A CT is a high-density plasma blob with self-organized magnetic confinement, and its characteristics make it an ideal carrier for central fueling in fusion devices.
The CT injection system is a novel fueling device centered on such plasma blobs. Driven by a pulsed high-power power supply, the system generates stable CT plasma within coaxial electrodes, which undergoes secondary acceleration to form a high-density plasma blob capable of long-distance stable propagation.
System discharge tests show that the peak discharge current of CT is 300 kA, the average electron density is \begin{document}$ 1.2\times {10}^{22}{\text{ m}}^{-3} $\end{document}
When applied to the EAST tokamak experiment, the results indicate that after CT injection, the plasma stored energy increases by 18%, the plasma density rises by 22%, and the plasma density rise rate is \begin{document}$ 0.4\times {10}^{20}{\text{ m}}^{-3}{\text{s}}^{-1} $\end{document}
Comparative studies with conventional gas puffing (GP) and supersonic molecular beam injection (SMBI) reveal that CT injection outperforms these techniques in terms of injected particle number, fueling efficiency, and particle confinement time during single-shot injections.
, Available online ,
doi: 10.11884/HPLPB202638.250312
Abstract:
Background Purpose Methods Results Conclusions
Owing to their simple configuration, stable operating behavior, and high electronic efficiency, magnetrons have been extensively employed in high-power microwave applications. Nevertheless, the output capability of a single microwave source is inherently constrained, making it difficult to satisfy the increasing demands of high-power applications. Magnetron array configurations offer an effective approach for enhancing the peak power of microwave systems.
To address the demand for frequency controllability and output consistency in large-scale magnetron arrays, this work integrates the advantages of injection locking and mutual coupling locking and proposes an injection-locking-based amplitude consistency control scheme for coupled magnetron arrays.
Five magnetrons are interconnected through directional couplers and coaxial lines to form a cascaded mutually coupled structure, in which an external signal is injected solely into the central magnetron to pull and control the operating frequency of the entire array via coupling paths. High-power experimental measurements were performed to systematically collect and analyze the output signals under five operating conditions, including free-running operation, mutual coupling only, and external injection at frequencies of 2.466 GHz, 2.465 GHz, and 2.464 GHz.
The experimental results indicate that introducing an external injection signal under the mutually phase-locked condition modifies the overall frequency characteristics of the cascaded magnetron array, thereby affecting the amplitude distribution of the array output signals. Moreover, effective regulation of the output amplitude of the magnetron array can be realized by tuning the frequency and power of the injected signal. The dispersion of output amplitudes under different conditions is quantitatively characterized using the sample variance of the power spectral density peak of the output signal, and the results show that, at an injection power of 100 W, the variance decreases from 1.868 to 0.446, indicating a significant improvement in amplitude consistency.
This approach offers strong scalability and practical applicability and is well suited for coherent power combining and phase-scanning applications in large-scale magnetron array systems.
, Available online ,
doi: 10.11884/HPLPB202638.250473
Abstract:
Background Purpose Methods Results Conclusions
Advanced sheet electron beam vacuum electron devices, particularly Ka-band traveling-wave tubes, are required to meet increasingly stringent broadband operational demands. However, energy leakage and impedance mismatch at millimeter-wave output interconnections remain major challenges that limit transmission efficiency and bandwidth performance.
To address these challenges, this work aims to design and validate a broadband, high-efficiency output circuit for a Ka-band sheet beam TWT. A novel non-contact double-layer choke-mode output circuit with an air-gap configuration is proposed to suppress leakage and enable broadband operation.
The design is based on the fundamental theory of conventional rectangular waveguides. The output circuit structure is carefully optimized, and matching stepped waveguides are introduced to improve impedance matching and reduce reflections. A comprehensive electromagnetic simulation model is developed and analyzed using High-Frequency Structure Simulator (HFSS). Furthermore, cold-test measurements are conducted on a fabricated prototype to experimentally verify the design.
HFSS simulation results show that the choke grooves effectively suppress parasitic leakage while enabling broadband transmission. The proposed output circuit achieves an absolute bandwidth of 11.9 GHz with a return loss better than −20 dB. The simulated transmission efficiency reaches 93.3%, corresponding to a relative bandwidth of 36.9%, which satisfies broadband operation requirements. Experimental cold-test results are in good agreement with the simulations, confirming the validity of the design.
Both simulation and experimental results demonstrate that the proposed choke-mode output circuit exhibits wide operating bandwidth, high transmission efficiency, low reflection, and effective voltage depression capability. The structure also shows strong anti-interference performance and operational reliability, making it well suited for high-power, broadband millimeter-wave sheet beam TWT applications.
, Available online ,
doi: 10.11884/HPLPB202638.250358
Abstract:
Background Purpose Methods Results Conclusions
In the 2024 series of Beirut explosions in Lebanon, terrorists hid trace high-explosive materials in electronic products to carry out attacks, exposing the shortcomings of the current detection system. Existing trace detection technologies cannot penetrate the casings of electronic products, while in bulk detection technologies, CT has limitations in imaging plate-like components such as mobile phones, and conventional X-ray security inspectors lack sufficient resolution. Neither of these can meet the detection needs. Computed Lamography (CL) technology is suitable for detecting plate-like components but lacks specialized research on trace explosives.
This study aims to explore the adaptation path of dual-energy CL technology to trace explosive detection and provide a technical solution for the accurate identification of hidden explosives in electronic products.
A simulation model of a mobile phone containing trace TNT and an R-value measurement model were built using Geant4 to obtain dual-energy X-ray projection data. In MATLAB, the POCS-TVM algorithm was used for image reconstruction, and the ratio of attenuation coefficients (R-value) was calculated to determine the effective atomic number of substances for explosive identification.
CL technology overcame the imaging limitations of CT for plate-like components. The R-value-based algorithm showed that the effective atomic number of TNT was 7.1388 , which fell within the range of 7.1-7.4 for explosives. Additionally, the correlation coefficient of the fitted curve for low-high energy projection data reached 0.999.
This study verifies the feasibility of dual-energy CL for trace explosive detection, provides a new technical path for identifying hidden explosives in electronic products, and is of great significance for enhancing nuclear security and anti-terrorism security inspection capabilities.
, Available online ,
doi: 10.11884/HPLPB202638.250429
Abstract:
Background Purpose Methods Results Conclusions
Tandem pumping scheme is commonly employed for high power fiber laser systems, where the 1 018 nm fiber laser serves as the most prevalent pump source. However, the output power of monolithic 1 018 nm fiber lasers is limited to one-kilowatt level due to the amplified spontaneous emission (ASE) effect. This limitation necessitates the use of a large number of these pump sources in tandem-pumped fiber laser systems, resulting in bulky and complex configurations.
This paper presents a modeling and optimization framework for scaling the power of 1 018 nm fiber lasers.
The framework, built upon the beam propagation method and broad-spectrum rate equations, targets the optimization of critical parameters to strategically balance laser efficiency against signal-to-ASE ratio.
Guided by the framework, a bidirectional pumping scheme was employed alongside an optimized fiber coil diameter, which effectively suppressed both ASE and the transverse mode instability. This approach enabled a monolithic output power of 1.94 kW at 1 018 nm, with an optical-to-optical efficiency of 76.38%, a signal-to-ASE ratio of 33.22 dB, and a beam quality factor M2 of 1.91.
By achieving a monolithic 2-kW 1 018 nm laser, this work enhances the compactness and integration of high-power fiber lasers with tandem pumping scheme, thus enabling future breakthroughs in the power and brightness scaling of tandem-pumped fiber lasers.
, Available online ,
doi: 10.11884/HPLPB202638.250398
Abstract:
Background Purpose Methods Results Conclusions
SiC-based light-initiated multi-gate semiconductor switches (LIMS) deliver superior response speeds due to the faster injection of photo-generated carriers compared to conventional electrically injected carriers. They can be used in a variety of applications, including radars, accelerators, and pulse sources.
Regarding the problems such as the long falling edge and slow turn-off speed of LIMS, an anode structure design with turn-off capability is proposed.
The model and its parameters are calibrated based on experimental data, and the simulation is used to study the conduction characteristics of devices with a turn-off anode structure.
The simulation results show that devices with a turn-off anode structure can achieve positive feedback in the pnpn configuration following laser activation, thereby increasing the conduction current. When the laser pulse ends, the recombination of photo-generated carriers and the extraction of carriers from the base region by the turn-off anode structure significantly enhance the turn-off speed of the device.
With a 4 kV anode bias and a peak current of several hundred amperes, the modified LIMS reduces the full-width-at-half-maximum of the current pulse from 0.79 µs to <100 ns and shortens the turn-off time to 0.6 µs. These results indicate suitability for repetitive operation at kilohertz frequencies and above.
, Available online ,
doi: 10.11884/HPLPB202638.250420
Abstract:
Background Purpose Methods Results Conclusions
High-power Yb-doped fiber lasers operating in the 1 μm band have been widely applied in fields such as laser processing, biomedicine, and national defense security. However, with the continuous increase in output power, traditional large-core fibers are susceptible to transverse mode instability (TMI) and stimulated Raman scattering (SRS), among other nonlinear effects. Based on their unique anti-resonant light-guiding mechanism, all-solid anti-resonant silica fibers (AS-ARFs) can realize ultra-large mode area (LMA) propagation while suppressing higher-order modes (HOMs), thus providing an innovative technical approach for balancing high power and high beam quality. Nevertheless, for active Yb-doped AS-ARFs targeting high-power gain applications, the influence mechanism of core refractive index fluctuations on mode characteristics and the fusion-splicing transmission characteristics of “step-index fiber - AS-ARF” structures have not been systematically investigated, which restricts their practical application process.
To address the above problems, this study aims to clarify the critical value of refractive index variation for maintaining the original light-guiding mechanism of AS-ARFs, verify their capabilities of low loss, large mode area and beam quality maintenance, explore the fusion-splicing coupling transmission laws between SIFs and AS-ARFs, quantify the core control parameters of active AS-ARFs, and provide theoretical support for their fabrication process optimization and coupling scheme design.
A six-ring AS-ARF theoretical model was constructed, combined with theoretical derivation and numerical simulation: Comsol Multiphysics was used to analyze the mode characteristics and the influence of refractive index fluctuations, and the Rsoft-BeamPROP module (based on the beam propagation method) was adopted to simulate the light transmission laws in the fusion-splicing coupling scenario.
The critical value of refractive index variation was clarified; the designed AS-ARFs were verified to have the characteristics of low loss, large mode area and excellent beam quality at the target wavelength; the fusion-splicing coupling transmission laws were revealed, and the transmitted energy attenuation was less than 2% when the incident beam diameter matched the core diameter of AS-ARFs.
This study realizes the quantification of core control parameters for active AS-ARFs, laying an important theoretical foundation for the fabrication process optimization of Yb3+-doped AS-ARFs (with a focus on refractive index uniformity control) and the design of practical coupling schemes.
, Available online ,
doi: 10.11884/HPLPB202638.250367
Abstract:
Background Purpose Methods Results Conclusions
High-energy flash X-ray photography has important applications in the hydrodynamic experiments. As an important means of generating multi-pulse X-ray, the technical scheme of multi-pulse linear induction accelerators (LIA) of each countries have their own characteristics.
Based on requirements for the compactness, mobility, and high reliability of multi-pulse LIAs, the project team is exploring various novel multi-pulse power source technologies that can be used for multi-pulse LIAs.
In this paper, a 100 kV four-pulse generation technology is explored, that is, a low-pressure pseudo-spark switch of tens of kV is used to drive the Blumlein line of tri-coaxial cables to generate multi-pulse high voltage, and the multi-pulse high voltage of tens of kV is superimposed by an induction voltage adder to generate a multi-pulse high voltage of 100 kV. The same four sets of pulse high voltage generators are used to output multi-pulse high voltage of 100 kV, which are converged by a coaxial high-voltage diode to obtain four-pulse high voltage output of 100 kV.
Simulation and experimental results show that the scheme could generate four-pulse high voltage of more than 100 kV with adjustable pulse interval.
This compact and movable 100 kV four-pulse high voltage generator is expected to become a new multi-pulse power source for multi-pulse LIAs.
, Available online ,
doi: 10.11884/HPLPB202638.250450
Abstract:
Background Purpose Methods Results Conclusions
Unmanned aerial vehicles (UAVs) pose significant military threats and civil security risks, and microwave technology has become a core counter-UAV means due to its low cost, area-effect engagement, and all-weather capability. Research on UAV microwave effects is the foundation for counter-UAV equipment development and protection design.
This paper aims to systematically review the research progress of UAV microwave effects, clarify existing challenges, and provide directional references for future studies.
By combing through domestic and foreign relevant research, this review summarizes the characteristics of different microwave effects, analyzes key influencing factors, and sorts out current research limitations and development trends.
Front-door effects involve coupling through intentional electromagnetic channels (e.g., data links) with low-noise amplifiers as sensitive components, and thresholds are related to frequency matching; back-door effects rely on unintentional channels (e.g., cables, housing gaps) with cables as the main path, but relevant research is insufficient; system-level effects show hierarchical failure, affected by UAV models, microwave parameters, and attitudes. Current research faces “black box” coupling mechanisms, fragmented methods, and inadequate connection with protection design.
Future research should focus on multi-path collaborative coupling modeling, complex scenario assessment, and countermeasure-protection collaborative technologies. This review provides a systematic reference for the field, supporting counter-UAV equipment development and safe UAV application.
, Available online ,
doi: 10.11884/HPLPB202638.250392
Abstract:
Background Purpose Methods Results Conclusions
Typically, radiation detectors require an additional coupled scintillator layer to convert incident radiation rays into optical signals, which are then received by the detector. Compared to other types of glass, lead fluoride (PbF2) glass has a high refractive index, and when electrons pass through a lead fluoride crystal, they generate Cherenkov light. As a result, lead fluoride itself can function as a scintillator.
Using a lead fluoride crystal as the optical window of a detector enables it to both generate and detect light. This optimizes the optical transmission and detection performance, shortens the conversion time from the reaction medium to photons, improves the detector’s efficiency, and provides an experimental foundation for future applications in ultrafast detection.
After cleaning components such as the cathode input window, ceramic parts, and anode of the photomultiplier tube, a transition indium sealing film layer is deposited on the cathode input window. The ceramic and metal components are then sealed and assembled into a tube shell using a hydrogen furnace. Indium sealing solder is melted into the tube shell’s indium sealing groove, and the tube shell is laser-welded to the anode. The processed tube shell, microchannel plate (MCP), and anode are assembled according to the designed structure. After assembly, the tube shell components and cathode window are mounted on a transfer-type cathode activation and exhaust station. Cathode activation and MCP electron scrubbing processes are then performed. Upon completion of these steps, the tube shell and cathode window are sealed together using indium sealing, resulting in the fabrication of an MCP-type photomultiplier tube bare tube.
Two PbF2-window MCP-PMTs were successfully prepared, and their electrical performance, including quantum efficiency and operating voltage, can be measured.
By integrating lead fluoride crystals, fast-time-response microchannel plates, and a fast-time coaxial conical anode, this study has successfully addressed key technical challenges in the preparation of lead fluoride crystals as the optical window for photomultiplier tubes. Post-fabrication performance tests indicate that core parameters such as quantum efficiency, gain, and rise time are generally comparable to those of conventional fast-time-response MCP-PMTs.
, Available online ,
doi: 10.11884/HPLPB202638.250242
Abstract:
Background Purpose Methods Results Conclusions
Precise γ-ray spectrum analysis is essential for nuclide identification and activity quantification, but faces significant challenges when using low-resolution detectors such as CLYC scintillators in complex radiation fields. The limited energy resolution of these detectors often leads to overlapping peaks and obscured characteristic spectral features, which complicates accurate spectrum interpretation.
This study aims to overcome the inherent energy resolution limitations of CLYC detectors by developing a spectrum deconvolution method that can recover clear spectral information and separate overlapping peaks in complex γ-ray spectra.
A detector energy response matrix was constructed by combining Monte Carlo simulations to calculate γ-ray energy response functions with an interpolation method. Response functions were derived across the 0～3 MeV energy range at intervals of 0.05 MeV to ensure high precision. Spectrum deconvolution was then performed using the Maximum Likelihood Expectation Maximization (MLEM) algorithm, which was then applied to analyze the original complex spectrum.
The method was validated by unfolding the spectra of a 226Ra source, a mixed 60Co - 137Cs source, and the complex spectrum of 152Eu. The unfolded spectrum exhibited well-resolved characteristic peaks, effective separation of severely overlapping spectral regions, and stable quantitative results for characteristic peak areas.
The proposed approach significantly enhances the precision of γ-ray spectrum analysis with CLYC detectors. It successfully reveals the energy and intensity information of incident γ-rays, mitigates the detector’s resolution limitations, and provides a reliable method for analyzing spectrum in complex radiation environment.
, Available online ,
doi: 10.11884/HPLPB202638.250281
Abstract:
Background Purpose Method Results Conclusions
When using the Monte Carlo method for radiation shielding simulations, the efficiency is low. Employing specific variance reduction techniques is one of the methods to accelerate radiation shielding simulations, while another more universal approach is to use large-scale parallel technology to enhance the simulation speed from the hardware aspect. At present, due to the enormous demand for computing power triggered by the development of artificial intelligence technology, major supercomputing platforms have steadily improved their support for large-scale GPU parallel architectures. To adapt to the current and future GPU parallel architectures of supercomputing platforms, it is necessary to develop Monte Carlo transport algorithms suitable for GPU platforms.
This paper aims to accelerate fixed-source calculation of the NECP-MCX Monte Carlo particle transport code by utilizing GPU parallel, thereby enhancing the efficiency of radiation shielding transport simulations.
This paper analyzes the characteristics of the GPU event-based parallel algorithm under the fixed-source mode. The GPU event-based parallel algorithm has been preliminarily implemented within the NECP-MCX code and was tested and analyzed using a simple fixed-source problem.
The results show that the maximum number of simultaneous simulated events is positively correlated with the simulation speed. Sorting particle information can accelerate the simulation by 28%, and the GPU parallel implementation is 25 times faster than the single-core CPU implementation.
The initial implementation shows significant potential for acceleration; however, further research is essential to fully exploit its capabilities and optimize performance.
, Available online ,
doi: 10.11884/HPLPB202638.250342
Abstract:
Background Purpose Methods Results Conclusions
In all-solid-state Marx pulse generators, the isolated gate driver plays a critical role in ensuring reliable high-voltage and high-speed switching. Conventional isolation driving schemes based on magnetic-core transformers often suffer from large volume, high cost, and poor integration, which limit further miniaturization and system-level integration.
To address these issues, this study proposes a synchronous isolated gate driving scheme based on a PCB-embedded coreless transformer, aiming to reduce driver size and cost while improving integration and manufacturability for all-solid-state Marx pulse generator applications.
The proposed coreless transformer was first modeled, and its key electromagnetic parameters were extracted using Q3D electromagnetic simulation and validated through experimental measurements. Based on theoretical analysis and LTspice simulations of the driving circuit, the operating principles and driving sequence characteristics were investigated and compared with those of conventional magnetic-core transformer-based drivers. Finally, a prototype driving system was developed and experimentally evaluated.
Simulation and experimental results show that the proposed PCB coreless transformer-based driving scheme exhibits a wide dynamic driving range, excellent electrical isolation performance, and good compatibility with standard PCB manufacturing processes. The experimental waveforms are consistent with theoretical analysis and simulation results, confirming the correctness of the proposed design and modeling approach.
The proposed synchronous isolated driving scheme based on a PCB coreless transformer provides an effective solution to the challenges of volume, cost, and integration in conventional isolation drivers for all-solid-state Marx pulse generators. The results demonstrate its feasibility and strong potential for practical engineering applications in compact and highly integrated pulsed power systems.
, Available online ,
doi: 10.11884/HPLPB202638.250378
Abstract:
Background Purpose Methods Results Conclusions
High-fidelity neutronics simulation of nuclear reactor cores, particularly those with complex geometries such as the AP1000, remains computationally challenging. Efficient deterministic methods that can achieve Monte Carlo-level accuracy are highly desirable for design and analysis.
This study aims to develop, apply, and validate the FLASH code, which implements an advanced Fission Response Function (FRF) algorithm, for performing efficient and accurate full-core, pin-wise neutronics calculations of the AP1000 reactor core.
The FRF database was generated through reference-state simulations using the Serpent Monte Carlo code. To enhance accuracy in complex geometries, the methodology incorporated a local inter-assembly environmental correction factor to address fuel assembly heterogeneity and a predictor-corrector scheme to precisely simulate reflector environmental effects. The performance of the FLASH code was validated against reference Monte Carlo solutions under Hot Zero Power (HZP) conditions.
The validation results demonstrated high accuracy. Deviations in the effective multiplication factor (keff) were within +220 pcm for all 2D axial slices and +209 pcm for the full 3D core calculation. The root-mean-square error (RMSE) was below 1.1% for the 2D pin power distribution, while the 3D pin power RMSE was 1.05% and the 3D assembly power RMSE was 0.67%. In terms of efficiency, the FLASH code completed the pin-wise full-core 3D calculation for the AP1000 in 106 seconds using 64 CPU cores.
The developed FLASH code, based on the FRF algorithm with integrated correction schemes, successfully bridges the gap between efficiency and high fidelity. It provides a rapid and accurate computational tool for AP1000 core analysis, confirming the practicality and effectiveness of the proposed methodology for detailed reactor physics calculations.
, Available online ,
doi: 10.11884/HPLPB202638.250386
Abstract:
This paper briefly reviews the series of work carried out by the research team from the Laser Fusion Research Center, China Academy of Engineering Physics, based on the Xingguang-III and Shenguang-II Upgrade laser facilities, in the field of laser-driven neutron source generation and applications. In terms of generation mechanisms, it highlights explorations of several technical approaches, including enhancing photo-nuclear neutron production efficiency through novel target design, increasing neutron yield based on the target normal sheath acceleration mechanism, and obtaining high-quality neutron sources via collisionless electrostatic shock acceleration. On the application front, preliminary experimental studies have been conducted in areas such as fast neutron radiography, material radiation effects, and nuclear material detection, demonstrating the potential application value of such neutron sources as short-pulse, high-flux sources. With continuous advancements in laser technology and ongoing optimization of generation mechanisms, this new type of neutron source is expected to play an increasingly important role in basic scientific research, nuclear energy technology development, and industrial applications, providing new research tools and technical support for the development of related disciplines.
This paper briefly reviews the series of work carried out by the research team from the Laser Fusion Research Center, China Academy of Engineering Physics, based on the Xingguang-III and Shenguang-II Upgrade laser facilities, in the field of laser-driven neutron source generation and applications. In terms of generation mechanisms, it highlights explorations of several technical approaches, including enhancing photo-nuclear neutron production efficiency through novel target design, increasing neutron yield based on the target normal sheath acceleration mechanism, and obtaining high-quality neutron sources via collisionless electrostatic shock acceleration. On the application front, preliminary experimental studies have been conducted in areas such as fast neutron radiography, material radiation effects, and nuclear material detection, demonstrating the potential application value of such neutron sources as short-pulse, high-flux sources. With continuous advancements in laser technology and ongoing optimization of generation mechanisms, this new type of neutron source is expected to play an increasingly important role in basic scientific research, nuclear energy technology development, and industrial applications, providing new research tools and technical support for the development of related disciplines.
, Available online ,
doi: 10.11884/HPLPB202638.250330
Abstract:
Background Purpose Methods Results Conclusions
With the continuous advancement of photoelectric applications such as LiDAR, three-dimensional sensing, and free-space communication towards longer distances, larger fields of view, and higher precision, large-spot, nanosecond-pulse lasers are progressively emerging as a critical type of light source, owing to their advantages in far-field uniform illumination and weak signal detection.
To address the challenges of amplitude distortion and sampling difficulties in beam quality measurements of large-spot, nanosecond-pulse lasers caused by optical path shaping distortions, transient capture limitations, and coherence requirements, this paper proposes a beam quality measurement system tailored for nanosecond pulsed large-aperture lasers.
The system employs a three-dimensional stepping platform combined with a photodetector to reconstruct the spatial intensity distribution of the beam, and incorporates a multi-channel peak-hold circuit to accurately latch pulse peaks, thereby ensuring transient fidelity in amplitude acquisition. To mitigate non-ideal conditions such as partial beam truncation and incomplete boundaries, a circle-fitting method is introduced as a complement to the second-moment calculation of energy, enhancing the robustness of beam size evaluation.
Experiments employing a typical vertical-cavity surface-emitting laser (VCSEL) were conducted through multi-position 3D axial scanning, comparing the consistency of beam size and energy distribution measured by different methods.
The results verify the measurement reliability and applicability of the proposed system under large-spot, nanosecond-pulse conditions, offering an effective means for laser beam quality assessment in related applications.
, Available online ,
doi: 10.11884/HPLPB202638.250424
Abstract:
Background Purpose Methods Results Conclusions
Diamond is considered a promising candidate for photoconductive semiconductor switches (PCSSs) due to its exceptional material properties.
However, the development of high-performance diamond PCSSs is primarily impeded by their high on-state resistance and relatively low breakdown voltage. This study aims to improve the performance of the diamond PCSSs.
Passivated with Si3N4, vertical PCSSs were fabricated using nitrogen-doped single-crystal diamonds with different doping concentrations and thicknesses. The doping concentrations of diamond samples were analyzed. The photoresponse of the PCSSs was characterized under 532 nm laser excitation over a range of DC bias voltages.
The experimental results showed that the nitrogen-doped diamond PCSSs present a large on/off ratio (～1011) along with sub-nanosecond rise and fall times. Among them, the diamond PCSS device with the highest nitrogen doping concentration exhibited the minimum on-state resistance. By reducing material thickness, a peak output power of 128 kW was achieved at a bias voltage of 4 kV (corresponding to the electric field strength of 110 kV/cm), with the PCSS exhibiting an on-state resistance of 28.9 Ω, further improving the device performance.
Through the design of nitrogen doping concentration, reduction of substrate thickness, and application of Si3N4 passivation, this work successfully developed diamond PCSSs with good performance, paving the way for the development of high-performance diamond PCSSs.
, Available online ,
doi: 10.11884/HPLPB202638.250168
Abstract:
Background Purpose Methods Results Conclusions
Gamma and thermal neutron imaging are important non-destructive testing methods, which are complementary in many aspects. The thermal neutron and Gamma bimodal imaging can combine the advantages of both. Compares with single beam imaging, the bimodal imaging has the ability to identify different substances and the sensitivity to both nuclides and elements simultaneous.
Utilizing the reaction between protons and target material producing neutrons and Gamma together, based on the 18 MeV cyclotron accelerator being developed by the Institute of Atomic Energy, this paper designs a bimodal imaging neutron source by simulation.
Beryllium with a high （p, n） reaction cross-section is selected as the neutron target to generate neutrons. To obtain thermal neutrons with higher flux, polyethylene is used as the neutron moderator and reflector. By the different spatial distributions of thermal neutrons and Gamma, these two types of radiation are separately extracted from different directions. Besides, by designing the neutron and Gamma exits on polyethylene, high neutron flux and Gamma beams are simultaneously obtained.
After simulation optimization, the thermal neutron flux at the thermal neutron outlet can reach 1.78×1010 n/（cm2·s） , and the gamma dose at the gamma outlet can reach 2.23×104 rad/h.
This paper design a neutron source for thermal-neutron-gamma imaging based on the 18 MeV/1 mA cyclotron accelerator. The design efficiently extracts thermal neutron flux and gamma flux from a single target, implementing a single-target-dual-source configuration.
, Available online ,
doi: 10.11884/HPLPB202638.250453
Abstract:
Background Purpose Methods Results Conclusions
Solid-state linear transformer drivers (SSLTDs), featuring modular architecture, solid-state implementation, high reliability, and high repetition-rate capability, have become an important development direction in pulsed-power technology.
This paper proposes and develops a compact SSLTD based on a stacked Blumlein pulse generation module (SBPGM) and experimentally validates its performance.
The SBPGM integrates a hybrid pulse-forming network composed of high-voltage ceramic capacitors and the distributed inductance of PCB traces, a series--parallel IGBT switching array, and inductively isolated gate-driver circuits. The proposed common-ground bipolar-charging SBPGM topology eliminates the need for high-voltage isolation within an individual module and equalizes the driver insulation voltage stress, thereby significantly improving the compactness and reliability of the overall system.
Circuit simulations of a single SBPGM verify the voltage-doubling behavior and the desired high-voltage isolation characteristics, producing a 10.8 kV output under a charging voltage of 5.5 kV. Based on this module, a 30-stage SSLTD prototype is constructed. With a per-stage charging voltage of 5 kV and a 90 Ωwater load, the prototype generates a 279 kV quasi-square pulse with a peak current of 3.1 kA, a pulse width of 77 ns, and a rise time of 22.4 ns at a repetition rate of 50 Hz, corresponding to a peak power of 0.9 GW.
This SSLTD adopts a modular, scalable architecture. The SBPGMs are electrically and mechanically consistent yet independent, enabling straightforward voltage scaling and simplified implementation. Experiments confirm compact size and high power density, demonstrating the potential of high-repetition-rate all-solid-state pulsed-power sources.
, Available online ,
doi: 10.11884/HPLPB202638.250395
Abstract:
Background Purpose Methods Results Conclusions
Alumina (Al2O3) ceramics are extensively employed as insulating components in vacuum electronic devices. However, under high voltage, charge accumulation on their surface can easily lead to surface flashover, which severely degrades the insulation performance of the device and affects its operation. Therefore, enhancing the vacuum surface insulation performance of Al2O3 ceramics holds significant academic value and practical implications. Surface coating represents a widely adopted strategy for enhancing the insulation performance of Al2O3 ceramics. Nevertheless, the specific influence of the glass phase within the coating on the insulating properties remains largely unexplored.
The present work is dedicated to exploring how the glass phase in coatings affects the vacuum insulation performance of Al2O3 ceramics.
A Cr2O3-based coating was fabricated on the surface of Al2O3 ceramics, and the effects of the glass phase within the coating on phase structure, surface morphology, secondary electron emission coefficient (SEE), surface resistivity, and the vacuum insulation performance of the coated ceramics were systematically investigated.
The results indicate that Al element from the substrate diffuses into the coating under high-temperature firing. The content of Cr2O3 phase in the coating exhibits a gradual decrease and eventually disappears with the rise of the glass phase content, causing it to fully react with the ceramic substrate to form Al2-xCrxO3 (0＜x＜2)、Mg(Al2-yCry)O4 (0＜y＜2), along with small amounts of ZnAl2O4 and (Na,Ca)Al(Si,Al)3O8. The coating improves the surface grain homogeneity and the density of the ceramic surface, although variations in the glass phase content have a negligible effect on its microstructure. Additionally, the Cr2O3 coating reduces both the SEE coefficient and the surface resistivity of the Al2O3 ceramic. However, as the glass phase content in the coating increases, both the SEE coefficient and surface resistivity of the coated ceramics exhibit a gradual upward trend. The optimal insulation performance is achieved when the glass phase content reaches 20%. At this point, the vacuum surface hold-off strength attains 119.63 kV/cm.
Modulation of the glass phase content in the surface coating enables the tunability of the vacuum surface insulation performance of the Al2O3 ceramics, with the performance improvement stemming from the decreased SEE coefficient and the appropriate surface resistivity.
, Available online ,
doi: 10.11884/HPLPB202638.250444
Abstract:
Background Purpose Methods Results Conclusions
The rapid advancement of high-power pulse technology towards practical application imposes higher demands on the self-breakdown stability of high-voltage gas switches.
This paper proposes a pre-ionization cathode switch concept, which utilizes an auxiliary annular blade edge to regulate initial electrons and an annular hemisphere to conduct the main current. A 300 kV-level pre-ionization annular cathode gas switch was designed.
With a switch gap of 35 mm, the field enhancement factor at the blade edge of the pre-ionization switch was designed to be 6.2, resulting in a ratio of 3.2 compared to the field enhancement factor at the hemisphere. Experimental investigations on the breakdown characteristics under microsecond-level pulses were conducted.
The results indicate that in nitrogen at 0.5 MPa and a repetition rate of 1 Hz, the pre-ionization gas switch achieved an average breakdown voltage of 322.5 kV with a amplitude jitter of 0.44%. Compared to a pure annular hemispherical switch, the pre-ionization switch exhibits a 17.6% reduction in breakdown voltage and an 82% decrease in amplitude jitter.
The experimental study demonstrates that this pre-ionization gas switch offers significant advantages in achieving high voltage and low jitter.
, Available online ,
doi: 10.11884/HPLPB202638.250419
Abstract:
Background Purpose Methods Results Conclusions
Yb(TMHD)3 (ytterbium tris (2,2,6,6-tetramethyl-3,5-heptanedionate)) is the irreplaceable vapor-phase dopant for fabricating high-gain Yb-doped silica laser fibers, and its exact Yb content dictates final fiber performance. The conventional oxalate gravimetric method requires 6 h per sample, incompatible with the real-time feedback demanded by modern preform manufacture.
In order to enhance the production efficiency,
we report a “nitric acid-hydrogen peroxide open-vessel digestion/EDTA complexometric titration” protocol. After 3 min oxidative decomposition of the organic matrix, the solution is buffered with hexamethylenetetramine (pH=5-6) and titrated with standard EDTA using xylenol orange (XO) as indicator.
The stoichiometric Yb3+ : EDTA ratio is 1∶1; the sharp colour change from rose-red to bright yellow with a relative standard deviation (RSD, n=11) of ≤ 0.5%. Mean recoveries for spiked Yb(TMHD)3 ranged 98.2%-100.2%. Results for ten commercial lots deviated <0.3% from the gravimetric reference, while the total analysis time was reduced from 6 h to 15 min.
The procedure is accurate, precise, inexpensive and field-robust, enabling on-site monitoring of Yb loading and immediate optimisation of preform deposition parameters.
, Available online ,
doi: 10.11884/HPLPB202638.250314
Abstract:
Background Purpose Methods Results Conclusions
High-power fiber lasers have become core devices in key fields such as industrial precision processing, advanced national defense equipment, frontier scientific research, and high-end medical equipment. However, the traditional R&D mode of high-power fiber lasers relies heavily on physical experiments, which are costly and time-consuming. Simulation technology, as an effective auxiliary tool, can significantly reduce experimental costs, shorten the development cycle, and accurately optimize key performance parameters, thus playing an irreplaceable role in promoting the practical application and technological innovation of high-power fiber lasers.
This study aims to systematically sort out and summarize the research progress of typical high-power fiber laser simulation software, clarify the current research status of this field, and provide practical references for the R&D and application of related simulation software in the industry.
This paper focuses on investigating mainstream high-power fiber laser simulation software at home and abroad, conducts in-depth analysis and comparison of their core functional characteristics, technical advantages, and applicable scenarios, and combs the research ideas and technical routes of high-power fiber laser modeling and simulation.
The study summarizes the main research features of high-power fiber laser modeling and simulation, discusses the key technical points in the effective verification and reliable application of simulation software, and clearly sorts out the latest research progress of typical simulation software.
This paper prospects the future development directions of high-power fiber laser simulation software, including the integration of multi-physics field simulation, high-precision model construction, artificial intelligence-enabled fiber laser design, as well as standardized interfaces and an open-source ecosystem. This study provides valuable theoretical and practical references for the R&D and upgrading of simulation software in related industries.
, Available online ,
doi: 10.11884/HPLPB202638.250430
Abstract:
Background Purpose Methods Results Conclusions
High-power femtosecond fiber lasers have extensive applications in advanced manufacturing, laser particle acceleration, high-order harmonic generation and so on. Coherent beam combining (CBC) of femtosecond fiber lasers serves as an effective technical approach to overcome the power limitations of single fibers and achieve high-power femtosecond laser output.
This work aims to develop a high-power femtosecond fiber laser CBC system to achieve kilowatt-level average power output with high stability.
The presented femtosecond fiber laser CBC system is based on a three-channel all-fiber chirped pulse amplifier. Phase adjustment and stable coherent combining of three laser amplifiers are achieved using fiber stretchers in combination with the stochastic parallel gradient descent (SPGD) algorithm.
At a total output power of 1219.1 W, the system delivers a combined power of 1072 W, corresponding to a combining efficiency of 87%. The combined beam exhibits near-diffraction-limited beam quality (M2=1.23), and the compressed pulse width is 899 fs. Furthermore, the influence of beam quality degradation on the combining efficiency is theoretically analyzed. The results show that the combining efficiency would decrease as the beam quality degradation rate increased, and the combining efficiency is more sensitive to the degradation of multi-channel beam quality.
The demonstrated all-fiber coherent beam combining system exhibits excellent stability and high-power output. Further power scaling can be realized by increasing the number of combining channels, thereby providing crucial technical support for the advanced applications of high flux ultrafast and ultra-intense lasers.
, Available online ,
doi: 10.11884/HPLPB202638.250291
Abstract:
Background Purpose Methods Results Conclusions
Boron Neutron Capture Therapy (BNCT) is an innovative binary targeted cancer treatment technology with high relative biological effect and cell-scale precision, but its clinical application is limited by the long computation time of traditional Monte Carlo methods for dose calculation and insufficient dosimetric research on head tumors.
This study aims to address these challenges by optimizing the Monte Carlo algorithm and developing pre-processing/post-processing modules, verifying the accuracy of the computational system, and analyzing the dosimetric characteristics of BNCT for head tumors.
Based on NECP-MCX, three acceleration strategies voxel geometry fast tracking, transport-counting integration, MPI parallel optimization were adopted to improve computational efficiency. Pre-processing (DICOM image parsing, material-boron concentration mapping, 3D voxel modeling) and post-processing (dose-depth curve, Dose-Volume Histogram (DVH), dose distribution cloud map) modules were developed. Both NECP-MCX and MCNP were used to calculate the dose distribution of a head tumor case (RADCURE-700) for comparison.
The single-dose calculation time was reduced from 2 hours to 9.4 minutes. The dose curves, DVH, and cloud maps from the two programs showed good consistency with relative deviations below 5% within 10 cm depth. BNCT achieved a tumor target volume D90 of 60 Gy in 63 minutes, with healthy tissue dose below 12.5 Gy.
The optimized NECP-MCX system realizes efficient and accurate dose calculation for BNCT. The consistent results validate its reliability, and the dosimetric analysis demonstrates BNCT’s potential for head tumor treatment, providing methodological support for clinical treatment planning.
, Available online ,
doi: 10.11884/HPLPB202638.250245
Abstract:
Background Purpose Methods Results Conclusions
Neutron multiplicity measurement technology, as a core method in the field of non-destructive testing, plays a critical role in determining the mass of fissionable material (235U). However, it suffers from technical bottlenecks such as prolonged measurement cycles and measurement deviations under non-ideal conditions.
This paper aims to explore feasible pathways for integrating neutron multiplicity measurement methods with neural network technology. The goal is to provide new research perspectives for advancing neutron multiplicity measurement technology toward greater efficiency and intelligence.
Leveraging Geant4 and MATLAB software, an Active Well Coincidence Counter (AWCC) simulation model is constructed to achieve high-precision simulation of the entire active neutron multiplicity measurement process. Building upon this, three neural networks—Backpropagation Neural Network (BPNN), Convolutional Neural Network (CNN), and Long Short-Term Memory network (LSTM)—are developed using the PyTorch framework to analyze and investigate neutron multiplicity distribution data.
Compared with traditional calculation methods based on the active neutron multiplicity equation, neural network models represented by CNN and LSTM demonstrate significant advantages in measurement accuracy and efficiency. Specifically, in terms of relative error metrics, neural network models can reduce errors to lower levels; in the time dimension of measurement, they substantially shorten data processing cycles, effectively overcoming the timeliness constraints inherent to traditional approaches.
This achievement fully validates the theoretical feasibility and technical superiority of the neural network-based neutron multiplicity measurement approach, providing a novel solution for advancing neutron multiplicity detection toward greater efficiency and intelligence. Subsequent work will enhance the adaptability and noise resistance of neural network models for complex data by increasing simulation scenario complexity and introducing diversified factors such as noise interference and geometric variations. Meanwhile, building upon simulation studies, physical experimental validation will be conducted using AWCC instrumentation to drive the transition of neural network-based neutron multiplicity measurement technology from simulation to engineering application.
, Available online ,
doi: 10.11884/HPLPB202638.250347
Abstract:
Background Purpose Methods Results Conclusions
Gigahertz-repetition-rate femtosecond fiber lasers have attracted increasing attention for applications requiring high temporal resolution and high average power, while most existing GHz fiber amplification systems are limited to fixed repetition rates.
This work aims to realize repetition-rate-tunable amplification of gigahertz femtosecond pulses within a single fiber-based platform by employing a passively harmonic mode-locked fiber laser as the seed source.
The seed laser provides stable pulse operation with repetition rates tunable from 1 to 3 GHz. A two-stage fiber amplification scheme combined with dispersion management is implemented to maintain stable amplification over the entire tuning range. In the pre-amplification stage, controllable chirp is introduced to achieve near-linear temporal broadening, which effectively suppresses excessive nonlinear effects during power scaling. Pulse compression is subsequently implemented at the output using single-mode fiber.
Experimental results show that stable pulse trains with regular temporal distribution are preserved throughout the tuning range. The maximum average output power reaches 2.1 W at a repetition rate of 3.1 GHz, while the shortest pulse duration of 195 fs is obtained at 2.0 GHz. After amplification, the side-mode suppression ratio remains higher than 33 dB.
These results indicate the feasibility of gigahertz repetition-rate-tunable amplification of femtosecond fiber lasers on a single all-fiber platform.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Display Method:
, Available online ,
doi: 10.11884/HPLPB202638.250337
Abstract:
Background Purpose Methods Results Conclusions
As an important branch of electromagnetic launch, multi-stage synchronous induction coil gun has become one of the hotspots of launch research because of its non-contact, linear propulsion and high efficiency. Among them, the armature outlet velocity is an important index, which is affected by many factors such as the structural parameters, material properties and coil circuit parameters. However, the existing research lacks theoretical analysis on various factors.
The purpose of this paper is to analyze theoretical approaches for improving the armature outlet velocity, and to explore the factors affecting it.
Based on the equivalent circuit model, this paper derives the analytical formula of armature induced eddy current and investigates these factors affecting the outlet velocity via finite element simulation.
Theoretical analysis shows that reducing the total inductance of the coil-armature equivalent circuit can increase the armature outlet velocity. Simulation results show that under the same initial electrical energy, reducing the number of turns of coils, reducing the cross-sectional shape factor of the rectangular wire, increasing the thickness and length of armature, and reducing the line inductance can improve the armature outlet velocity. Considering various factors, the simulated outlet velocity of 32 kg armature driven by 5-stage coil can reach 202.1 m/s, and the launch efficiency is 33.3%. The influence of various factors on the armature is in line with the theoretical analysis results.
The research content of this paper provides some theoretical support for the design of multi-stage synchronous induction coil gun scheme.
, Available online ,
doi: 10.11884/HPLPB202638.250310
Abstract:
Background Purpose Methods Results Conclusions
Fiber lasers have been widely used in numerous fields such as industrial processing and scientific research detection, due to their significant advantages including high efficiency, low cost, and miniaturization. In the R&D (research and development) and mass production of fiber lasers, the synchronous testing of core performance indicators such as power, spectrum, time-domain characteristics, and beam quality is a key technical support. It enables comprehensive evaluation of the device’s overall performance, accurate localization of design defects, optimization of production process parameters, and guarantee of consistent product delivery. However, the traditional testing mode requires temporarily building a dedicated test system for each laser under test. It has problems such as long time consumption, cumbersome operation, and low testing efficiency, making it difficult to meet the needs of large-scale production and high-efficiency R&D.
To address the above issues, this paper proposes an integrated synchronous testing system for multi-parameter fiber lasers. The system aims to realize the synchronous acquisition and testing of multiple indicators, including power, spectrum, time-domain characteristics, and beam quality. It further improves the scientificity of the comprehensive performance evaluation of lasers, provides reliable technical support for production practice and scientific research in related fields, and achieves the core goals of improving testing efficiency and simplifying testing processes.
The system achieves the integrated integration of multi-module hardware testing equipment, as well as standardized interfaces and external connections, based on optical principle design and precision mechanical structure design. From the perspective of safe operation, an emergency shutdown device for abnormal working conditions is equipped to ensure the safety of the system and the laser under test during the testing process. The control software adopts LabVIEW multi-threading technology to realize the synchronous acquisition and real-time transmission of various parameters.
The system can adapt to the testing needs of fiber lasers with an output power range of 80 W to 10 kW. During testing, users only need to connect the fiber end cap of the laser under test to the system, and can start multi-parameter synchronous testing through the upper computer software without manual intervention in the optical adjustment link. After the test, the system can automatically complete the analysis and processing of raw data and generate a standardized test report. Verification experiments conducted with a 10 kW fiber laser as the test object show that the system has good operability, reliability, test repeatability, and technical feasibility.
The system significantly improves the efficiency of multi-parameter testing of fiber lasers and greatly reduces the complexity of data processing, providing an efficient and reliable solution for scientific research and industrial laser testing.
, Available online ,
doi: 10.11884/HPLPB202638.250289
Abstract:
Oscillating-amplifying integrated fiber lasers (OAIFLs) have emerged as a promising technology in high-power laser applications by combining the structural simplicity and superior anti-reflection capability of oscillators with the high efficiency of amplifiers. This review systematically summarizes recent progress from both theoretical and experimental perspectives. Theoretically, the focus is on advances in modeling mode instability and nonlinear effects, aiming to provide optimization guidelines for achieving high-power output. Experimentally, OAIFLs have successfully realized kilowatt-level narrow-linewidth and 10-kW-class broadband laser output in conventional wavelength bands. Beyond these bands, research primarily targets1050 nm and 1018 nm fiber lasers. Furthermore, innovative dual-end output designs address core high-power challenges through distributed power extraction, significantly enhancing system power scalability. These advancements will accelerate broader applications in industrial processing, biomedical fields, and national defense. Analysis of current trends highlights key evolutionary pathways: benefiting from the integrated structure’s unique advantages in nonlinear management and amplified spontaneous emission (ASE) suppression, operational wavelengths are expanding from the conventional 1050 –1080 nm range toward shorter specialty bands; driven by demands in coherent beam combining and high-precision spectroscopy for high-brightness sources, output spectra are shifting from broadband to narrow-linewidth emission; gain media are evolving from conventional homogeneous fibers to specially designed geometric structures to simultaneously mitigate nonlinear effects and transverse mode instability (TMI) under high-power conditions; to meet needs in precision machining, spectroscopic sensing, and scientific research for lasers with high peak power and tailored temporal profiles, operational modes are diversifying from continuous-wave to varied pulsed regimes; and output configurations are advancing from simple single-end to sophisticated dual-end designs, effectively addressing key challenges in high-power laser delivery. Nevertheless, persistent limitations include insufficient universality of theoretical models and a lack of systematic experimental validation. Future research should emphasize two complementary dimensions. Theoretically, efforts must deepen model construction and mechanistic analysis—including refining temporal modeling, investigating TMI origins and nonlinear coupling mechanisms, and elucidating the physics of pump-timing-independent operation. Experimentally, the focus should be on continuously optimizing output performance—enhancing power and efficiency, improving spectral characteristics and beam quality, and advancing toward pulsed and supercontinuum generation capabilities.
Oscillating-amplifying integrated fiber lasers (OAIFLs) have emerged as a promising technology in high-power laser applications by combining the structural simplicity and superior anti-reflection capability of oscillators with the high efficiency of amplifiers. This review systematically summarizes recent progress from both theoretical and experimental perspectives. Theoretically, the focus is on advances in modeling mode instability and nonlinear effects, aiming to provide optimization guidelines for achieving high-power output. Experimentally, OAIFLs have successfully realized kilowatt-level narrow-linewidth and 10-kW-class broadband laser output in conventional wavelength bands. Beyond these bands, research primarily targets
, Available online ,
doi: 10.11884/HPLPB202638.250284
Abstract:
Machine learning (ML) has emerged as a transformative approach for advancing fiber laser technology, offering powerful solutions to overcome the limitations of traditional design, optimization, and control methods. This review systematically examines the integration of ML across the entire fiber laser ecosystem. It begins by categorizing fundamental ML paradigms, with a discussion of their respective applicability. The subsequent sections detail recent research progress in key areas including intelligent device design, which encompasses ML-assisted optimization of doped fibers, photonic crystal fibers, anti-resonant fibers, polarization-maintaining fibers, fiber gratings, and mode-selective couplers; laser simulation and prediction, focusing on models for power, temporal dynamics, and spectral evolution; intelligent control of laser output, covering adaptive mode-locking, coherent beam combining, and spatiotemporal pulse shaping; and laser characterization, highlighting ML-enhanced techniques for temporal pulse measurement, mode decomposition, and beam quality evaluation. The review further addresses prevailing challenges such as data dependency, model generalizability, interpretability, and computational efficiency, while outlining future directions toward developing more robust, efficient, and physically interpretable ML-driven fiber laser systems.
Machine learning (ML) has emerged as a transformative approach for advancing fiber laser technology, offering powerful solutions to overcome the limitations of traditional design, optimization, and control methods. This review systematically examines the integration of ML across the entire fiber laser ecosystem. It begins by categorizing fundamental ML paradigms, with a discussion of their respective applicability. The subsequent sections detail recent research progress in key areas including intelligent device design, which encompasses ML-assisted optimization of doped fibers, photonic crystal fibers, anti-resonant fibers, polarization-maintaining fibers, fiber gratings, and mode-selective couplers; laser simulation and prediction, focusing on models for power, temporal dynamics, and spectral evolution; intelligent control of laser output, covering adaptive mode-locking, coherent beam combining, and spatiotemporal pulse shaping; and laser characterization, highlighting ML-enhanced techniques for temporal pulse measurement, mode decomposition, and beam quality evaluation. The review further addresses prevailing challenges such as data dependency, model generalizability, interpretability, and computational efficiency, while outlining future directions toward developing more robust, efficient, and physically interpretable ML-driven fiber laser systems.
, Available online ,
doi: 10.11884/HPLPB202638.250376
Abstract:
Background Purpose Methods Results Conclusions
U-band fiber lasers are of significant value for applications in communications, sensing, and scientific research.
This paper employs a 1.55 μm fiber laser as the pump source and demonstrates a U-band 1.65 μm Raman fiber laser based on commercially available single-mode silica fiber. The effects of the Raman fiber length and the reflectivity of the output coupling fiber Bragg grating (OC-FBG) on the power conversion efficiency of the Raman laser were systematically investigated.
The optimal Raman fiber length was determined to be 2.1 km in experiment. Then, with the optimal Raman fiber length, experiments were conducted by varying the reflectivity of the OC-FBG to analyze its influence on the output power and spectral broadening of Stokes light. By combining the measured forward and backward Stokes powers with the collected forward and backward spectra, the optimal OC-FBG reflectivity under the current experimental conditions was determined.
The results indicated that as the Raman laser power increased, the broadening of the Stokes spectral linewidth reduced the effective reflectivity of the fiber Bragg grating, leading to backward power leakage, which became the main factor limiting the forward output power.
By selecting an OC-FBG with a low reflectivity of 15.7% and using a 2.1 km silica fiber as the Raman gain medium, a 1648.8 nm Raman laser output with a power of 10.1 W and a 3 dB bandwidth of 2.5 nm was achieved, corresponding to an optical-to-optical conversion efficiency of 65.2%.
, Available online ,
doi: 10.11884/HPLPB202638.250251
Abstract:
Background Purpose Methods Results Conclusions
Fiber lasers have gained extensive adoption across medical, telecommunications, industrial processing, and defense sectors owing to their exceptional beam quality, operational stability, compact architecture, and high reliability. Among them, narrow-linewidth linearly polarized fiber lasers have become a key research focus due to their outstanding spectral purity and coherence, with current efforts concentrated on further scaling their output power and brightness.
In this work, we demonstrate a 5.09 kW narrow-linewidth linearly polarized fiber laser system designed to overcome stimulated Brillouin scattering (SBS) and transverse mode instability (TMI).
A white-noise radio frequency phase modulation scheme is implemented to broaden the seed laser spectrum into a Gaussian profile with an 89 GHz full width at half maximum, enabling effective SBS suppression. A polarization-maintaining ytterbium-doped fiber (PMYDF) with low numerical aperture (about 0.05), large mode area (about 237 μm2), and high birefringence coefficient (4.23×10−4) is employed to simultaneously mitigate SBS and intermodal thermal coupling.
The system achieves 5.09 kW output power while maintaining an 89 GHz spectral linewidth, polarization extinction ratio above 19.6 dB, and beam quality factor of M2 < 1.2. No self-pulsing or temporal instability is observed at maximum power, confirming suppression of both SBS and TMI.
By employing a white-noise radio frequency signal to modulate the phase of a single-frequency laser, the SBS effect in high-power fiber laser systems is effectively suppressed. Concurrently, intermodal thermal coupling and SBS are further mitigated using a fabricated low-numerical-aperture, large-mode-area PMYDF. The demonstrated performance supports the feasibility of high-power, narrow-linewidth polarized fiber lasers for long-term stable operation.
, Available online ,
doi: 10.11884/HPLPB202638.250243
Abstract:
Background Purpose Methods Results Conclusions
The traditional Monte-Carlo (MC) method faces an inherent trade-off between geometric modeling accuracy and computational efficiency when addressing real-world irregular terrain modeling.
This paper proposes a fast MC particle transport modeling method based on irregular triangular networks for complex terrains, addressing the technical challenge of achieving adaptive and efficient MC modeling under high-resolution complex terrain scenarios.
The methodology consists of three key phases: First, high-resolution raster-format terrain elevation data are processed through two-dimensional wavelet transformation to precisely identify abrupt terrain variations and extract significant elevation points. Subsequently, the Delaunay triangulation algorithm is employed to construct TIN-structured terrain models from discrete point sets. Finally, the MCNP code’s “arbitrary polyhedron” macrobody definition is leveraged to establish geometric planes, with Boolean operations applied to synthesize intricate geometric entities, thereby realizing rapid automated MC modeling for high-resolution complex terrains.
The results demonstrate that the proposed method accurately reproduces terrain-induced effects on radiation transport, achieving high-fidelity simulations while significantly compressing the number of cells and enhancing computational efficiency.
This methodology represents a novel approach for large-scale radiation field modeling under complex terrain constraints, demonstrating broad applicability to MC particle transport simulations in arbitrary large-scale complex terrain scenarios.
, Available online ,
doi: 10.11884/HPLPB202638.250219
Abstract:
Background Purpose Method Results Conclusions
With the continuous development of nuclear power technology, reactor design has put forward higher requirements for the accuracy, efficiency and multi-functionality of nuclear computing software. The current mainstream Monte Carlo software has deficiencies in the balance between reactor radiation shielding design and nuclear design calibration, which restricts the critical simulation efficiency of the reactor core. Therefore, CNPRI has specifically developed the 3D Monte Carlo software LARCH 1.0 to meet the actual needs of nuclear power engineering design.
This study aims to optimize the particle energy search mechanism in Monte Carlo simulation and address the pain point of low efficiency in traditional search methods; thereby based on the optimized search method, the delta-tracking algorithm is further improved to enhance the efficiency of core critical calculation and provide efficient and accurate calculation support for reactor design.
During the development of the LARCH software, the core technological innovation lies in the adoption of a unified energy grid design to replace the traditional binary search and logarithmic search methods. Through the standardization and unification of the energy grid, the number of searches in the particle energy matching process is reduced, and the time consumption of a single search is shortened. Based on the unified energy grid technology, we further developed and optimized the delta-tracking algorithm to achieve the improvement of computing efficiency. By designing a targeted numerical verification scheme, the LARCH 1.0 software and the traditional Monte-Carlo software were compared and tested in reactor problem simulations.
The optimized technical solution has achieved remarkable results. The search method based on the unified energy grid has significantly reduced the time cost of particle energy search compared with the traditional method. Based on this, the optimized delta-tracking algorithm has increased the critical computing efficiency of the Monte-Carlo software core by approximately 25%.
The unified energy grid method and the optimized delta-tracking algorithm adopted by the LARCH 1.0 3D Monte-Carlo software provide an effective technical path for the efficiency improvement of the Monte Carlo software and significantly enhance the critical calculation efficiency of the reactor core. The application potential of this software indicates that it can provide more efficient and reliable numerical simulation tools for reactor design. More extensive engineering verification and functional iterations will be further carried out subsequently.
, Available online ,
doi: 10.11884/HPLPB202638.250234
Abstract:
Background Purpose Methods Results Conclusions
With the development of neutron calculation methods and improved modeling capabilities, the errors introduced by model approximations and discretization methods in nuclear reactor physics calculations have gradually decreased. However, nuclear data, due to the challenges in measurement, have become the key input parameter affecting computational accuracy.
In this study, a nuclear data adjustment module based on sensitivity analysis and the generalized linear least squares algorithm was developed within the self-developed sensitivity and uncertainty analysis platform, SUPES.
First, sensitivity analysis was used to determine the relationship between system responses and input parameter variations. Next, similarity analysis was applied to select experimental setups with high similarity at the neutron physics level. Finally, the generalized linear least squares algorithm was employed to minimize the error between computed and measured values, resulting in nuclear data adjustments.
The adjustment of the ACE format continuous energy database was performed on 22 cases from the critical benchmark HEU-MET-FAST-078. The numerical results show that the root mean square error of the effective multiplication factor (keff) was reduced from 3.10×10−3 to 1.53×10−3.
The comparison and analysis verified the correctness of the developed nuclear data adjustment module.
, Available online ,
doi: 10.11884/HPLPB202638.250393
Abstract:
Background Purpose Methods Results Conclusions
The retention and diffusion of helium on the surface of the first wall is one of the key problems in the study of magnetic confinement fusion. Laser-induced breakdown spectroscopy is the most promising technique for in-situ diagnosis of the first wall. Compared with the optical spectral range, laser-induced extreme ultraviolet spectroscopy has more advantages in sensitivity, noise suppression and accuracy.
To meet the requirement for high precision on-site measurement of helium impurity lines in magnetic confinement fusion, a ultra-high resolution EUV spectroscopy system was developed.
The grazing incidence Czerny-Turner structure was used in the spectrometer, and the luminous flux and spectral resolution were adjusted through an adjustable incidence slit. The ray tracing simulation was carried out using a self-developed optical design software. And the wavelength calibration and performance testing were carried out by microwave plasma light source.
The simulation results show that the spectral resolution is better than 20 000, and the experimental results indicate that the spectrometer achieves a spectral resolution of 0.001 4 nm at He II (30.3786 nm).
The spectrometer can meet the requirement for high-precision measurement of helium extreme ultraviolet spectral lines, and it is expected to provide an important theoretical support for the research on the helium retention and diffusion in the first wall.
, Available online ,
doi: 10.11884/HPLPB202638.250369
Abstract:
Background Purpose Methods Results Conclusions
The self-absorption effect of target materials plays a crucial role in shaping the performance of laser-driven X-ray sources, directly impacting their energy spectrum and angular distribution, which are critical parameters for applications such as high-resolution backlighting and radiographic diagnostics.
This study aims to systematically investigate how key parameters, including the electron source position relative to the wire target end-face, the diameter of the wire target, and the atomic number of the target material, affect the energy spectrum and angular distribution of emitted X rays.
A series of Geant4-based Monte Carlo simulations were performed using a validated wire target model. Key parameters were varied: electron source offset (50–150 μm), wire diameter, and target material (Cu, Mo, W, Au). The simulation model was benchmarked against experimental data obtained from the Xingguang-III laser facility.
The results indicate that varying the electron source position within the studied range has a negligible influence on both the photon energy spectrum and angular distribution. In contrast, increasing the wire diameter leads to enhanced absorption of low-energy photons, resulting in noticeable spectral hardening and a broadening of the angular distribution due to increased multiple scattering. Furthermore, higher-Z target materials (W, Au) significantly enhance the high-energy photon yield but concurrently induce greater angular divergence.
The findings provide quantitative insights into the self-absorption mechanism and its differential impact across parameters. This study offers concrete guidance for optimizing target design: selecting appropriate wire diameter and high-Z materials can tailor the spectral hardness and brightness, while mindful management of angular broadening is necessary for applications requiring high directivity.
, Available online ,
doi: 10.11884/HPLPB202638.250351
Abstract:
Background Purpose Methods Results Conclusions
Water-dielectric self-breakdown switches are critical components in pulsed power devices such as the 10 MA facility. The plate-sphere electrode structure is specifically designed to achieve simultaneous multi-channel discharge, which is essential for minimizing switch inductance and reducing timing jitter.
This study investigates the factors affecting multi-channel formation in a water-dielectric, three-electrode plate-sphere self-breakdown switch operating at 3 MV, with the aim of validating the theoretical formation criterion.
Theoretical analysis was conducted based on the specific parameters of the switch structure, focusing on key temporal characteristics influencing discharge behavior. Experimental validation was performed at the nominal breakdown voltage of 3 MV, utilizing diagnostic techniques to observe the development of discharge arcs across all electrode pairs.
The calculated characteristic value for multi-channel formation was determined to be 8.6 ns, exceeding twice the measured switch jitter time of 3 ns, thereby satisfying the theoretical criterion. Observations confirmed that discharge arcs initiated nearly synchronously at the three sphere electrodes and propagated toward the plate electrodes, with complete multi-channel formation achieved within approximately 30 ns.
The study validates the criterion for multi-channel discharge in the plate-sphere switch structure. The design effectively enables simultaneous formation of multiple discharge channels within tens of nanoseconds, meeting essential requirements for high-performance pulsed power devices and contributing to improved operational stability.
, Available online ,
doi: 10.11884/HPLPB202638.250327
Abstract:
Background Purpose Methods Results Conclusions
In the voltage multiplication process of a spiral generator based on the principle of vector inversion, its voltage efficiency is constrained by losses such as switching loss, transmission line loss and leakage inductance loss.
To quantitatively investigate the impact of key design parameters––including coil turn number n, dielectric/electrode thickness, average dielectric diameter D, magnetic core permeability, and switch position on leakage loss and overall efficiency.
This study employs a field-circuit collaborative simulation method for modeling and analysis.
The simulation results demonstrate that utilizing a high-permeability magnetic core can significantly enhance voltage efficiency; increasing D/n ratio improves output efficiency; while a higher turn number n boosts output voltage amplitude, it concurrently reduces voltage efficiency; enlarging the average diameter D enhances voltage efficiency but at the cost of increased device volume; reducing dielectric thickness benefits efficiency, though excessively thin layers risk insulation breakdown; and positioning the switch at the middle of the coil, rather than at the end, substantially increases voltage efficiency.
Furthermore, an in-depth analysis of the electromagnetic energy conversion process after switch closure reveals that a high-efficiency spiral generator must achieve complete conversion of magnetic energy into electric field energy while ensuring the electric fields in the active and passive layers are oriented in the same direction, which is essential for optimal performance.
, Available online ,
doi: 10.11884/HPLPB202638.250363
Abstract:
Background Purpose Methods Results Conclusions
In recent years, emerging application fields such as FLASH radiotherapy and flash radiography have created an urgent demand for high-repetition-rate linear induction accelerators (LIA) capable of operating at kHz-level frequencies. Whether the magnetic cores of induction accelerator cavities can effectively reset between repetitive pulses has become one of the critical factors determining the feasibility of high-repetition-rate LIA.
This paper focuses on the reset methods for magnetic cores in high-repetition-rate pulsed induction accelerator cavities.
Through high-voltage experiments and circuit simulations, various rapid reset methods for both amorphous and nanocrystalline magnetic cores were investigated and comparatively analyzed. Based on this work, experimental tests were conducted on the interpulse reset effectiveness of accelerator cavity cores using self-developed high-repetition-rate pulsed induction accelerator modules.
Research results indicate that nanocrystalline magnetic cores are more suitable for high-repetition-rate induction accelerator cavities. Different reset methods can achieve magnetic core reset at varying repetition frequencies.
Utilizing the inductor-isolated DC reset method, the existing device configuration can meet the reset requirements for nanocrystalline magnetic cores at a 10 kHz repetition rate. By leveraging the self-recovery capability of low-remanence nanocrystalline magnetic cores, automatic reset of accelerator cavity cores can be achieved at 100 kHz repetition rates.
, Available online ,
doi: 10.11884/HPLPB202638.250328
Abstract:
Background Purpose Methods Results Conclusions
The PFN (pulsed forming network)-Marx generator shows robust capabilities for enhancing the output efficiency and miniaturization level of pulsed power system, and offers the most significant potential for compact and lightweight design.
This study aims to develop a compact PFN-Marx generator that is capable of generating high-power pulses with flat-top duration, while maintaining low output jitter.
A tailored pulsed forming module (PFM) was developed by employing a non-uniform PFN sections reduced to 2, aiming for enhanced compactness. The influence of key circuit parameters on its output waveform was investigated. A PFN-Marx generator was designed and assembled by employing the PFMs and low-jitter plane-triggering-electrode gas switches et al.
The effects of key circuit parameters on the pulse shaping was quantitatively analyzed, and waveform tailoring of the PFM was achieved. The PFM could output a high-voltage pulse with a pulse width and flat-top duration (90%−90%) of about 150 ns and 80 ns, respectively. Once assembled into the Marx generator, it could deliver a 190 kV, 3.4 GW high pulsed power to a 10.6 Ω resistive load, while maintaining a flat-top duration of about 80 ns. When operating at a repetition rate of 50 Hz, it exhibits highly consistent output waveforms, with an output jitter as low as 2.4 ns.
A compact PFN-Marx generator was developed by employing a 2-sections tailored PFM that is capable of generating high-power pulses with flat-top duration. It is helpful for the development of compact Marx generator with the required waveform and low output jitter.
, Available online ,
doi: 10.11884/HPLPB202638.250362
Abstract:
Background Purpose Methods Results Conclusions
The rapid development of high-power microwave application technology presents significant challenges for the reliability and installability of pulsed power drivers.
The design methodology of a compact, lightweight Tesla-type pulsed power driver based on high-energy-density liquid dielectric Midel 7131 and a dual-width pulse-forming line (PFL) is introduced.
There was a key breakthrough in the miniaturization of the integrated Tesla transformer and PFL assembly. Through optimization of the electrical length of the short pulse transmission line and its impedance matching characteristics, longstanding challenges associated with conventional single-cylinder PFLs and extended transmission lines using transformer oil dielectrics have been effectively resolved. A high-elevation, high-vacuum oil impregnation technique was developed for the Tesla transformer, successfully mitigating partial discharge in oil-paper insulation systems and thereby enhancing the power rating and operational reliability of the PFL.
The developed pulsed power driver delivers a peak output power of 20 GW, a pulse duration of 50 ns, a pulse flat-top fluctuation of less than 2%, and a maximum repetition rate of 50 Hz. The system has demonstrated stable operation over continuous one-minute durations, accumulating approximately 200 000 pulses with consistent performance. The driver’s overall dimensions are 4.0 m (L)×1.5 m (W)×1.5 m (H), with a total mass of approximately 5 metric tons.
Compared to the conventional 20 GW Tesla-type pulsed power generator, this driver has achieved significant improvements in power density and miniaturization.
Display Method:
Status and recent progress of the XingGuang ultrashort and ultra-intense laser experimental platform
2026, 38: 031002.
doi: 10.11884/HPLPB202638.250390
Abstract:
This review summarizes the evolution and present capabilities of the XingGuang ultrashort and ultra-intense laser platform at the National Key Laboratory of Plasma Physics (CAEP), which integrates the XingGuang-III (XG-III) multi-pulse facility and the all-OPCPA SILEX-II multi-petawatt system. Targeting inertial confinement fusion (ICF), high-energy-density physics (HEDP), and matter under extreme conditions, the platform enables both extreme-state creation and time-resolved pump–probe measurements. We outline the system architecture, key enabling technologies, and experimental capabilities. The XG-III facility adopts a common-seed, split-and-amplify design that delivers femtosecond/picosecond/nanosecond beams with sub-picosecond timing jitter less than 1.32 ps; typical operating parameters include about 20 J/26.8 fs, about 370 J/(0.48–10 ps) and about 575 J/1 ns, with on-target focal spots below 10 μm (fs) and 20 μm (ps). SILEX-II employs a full optical parametric chirped-pulse amplification (OPCPA) chain to achieve a peak of power about 5 PW after compression to about 18.6 fs while retaining more than 90 J, combining greater than 1010 temporal contrast (tens of ps before the main pulse) with near-diffraction-limited focusing (about 3.3×4.0 μm FWHM) enabled by adaptive optics and achromatic compensation, reaching intensities above 1020 W/cm2. In addition, we present representative multi-beam, coordinated experiments enabled by the platform, including three-dimensional proton imaging of temperature-gradient-driven Weibel magnetic fields and energy-loss measurements of intense ion beams in warm dense plasmas, highlighting its strong potential for frontier research.
This review summarizes the evolution and present capabilities of the XingGuang ultrashort and ultra-intense laser platform at the National Key Laboratory of Plasma Physics (CAEP), which integrates the XingGuang-III (XG-III) multi-pulse facility and the all-OPCPA SILEX-II multi-petawatt system. Targeting inertial confinement fusion (ICF), high-energy-density physics (HEDP), and matter under extreme conditions, the platform enables both extreme-state creation and time-resolved pump–probe measurements. We outline the system architecture, key enabling technologies, and experimental capabilities. The XG-III facility adopts a common-seed, split-and-amplify design that delivers femtosecond/picosecond/nanosecond beams with sub-picosecond timing jitter less than 1.32 ps; typical operating parameters include about 20 J/26.8 fs, about 370 J/(0.48–10 ps) and about 575 J/1 ns, with on-target focal spots below 10 μm (fs) and 20 μm (ps). SILEX-II employs a full optical parametric chirped-pulse amplification (OPCPA) chain to achieve a peak of power about 5 PW after compression to about 18.6 fs while retaining more than 90 J, combining greater than 1010 temporal contrast (tens of ps before the main pulse) with near-diffraction-limited focusing (about 3.3×4.0 μm FWHM) enabled by adaptive optics and achromatic compensation, reaching intensities above 1020 W/cm2. In addition, we present representative multi-beam, coordinated experiments enabled by the platform, including three-dimensional proton imaging of temperature-gradient-driven Weibel magnetic fields and energy-loss measurements of intense ion beams in warm dense plasmas, highlighting its strong potential for frontier research.
2026, 38: 031003.
doi: 10.11884/HPLPB202638.260005
Abstract:
The rapid development of ultra-short and ultra-intense laser technology has greatly advanced frontier research in physics under extreme strong-field conditions. This includes compact accelerators, high-brightness radiation sources, nonlinear strong-field quantum electrodynamics, as well as the production and detection of axion dark matter based on intense lasers. Over the past decade, Shanghai Jiao Tong University has carried out systematic theoretical, simulation and experimental research in this field, and has successively built a relativistic plasma research platform based on a single-beam hundred-terawatt-level laser and an extreme relativistic plasma research platform based on a dual-beam hundred-terawatt-level laser with high-precision spatiotemporal synchronization. In this paper, we present the layout, key parameters and characteristics of the newly commissioned dual-beam Chongming Laser-plasma Experimental Facility (CLEF), and highlight both completed and ongoing scientific activities, including the studies on laser-solid high-order harmonic generation, laser-plasma wakefield acceleration, nonlinear Compton scattering, and the production and detection of axion dark matter driven by intense lasers. The completion and operation of this facility will provide an essential supporting platform for experimental research in the field of extreme relativistic plasma physics.
The rapid development of ultra-short and ultra-intense laser technology has greatly advanced frontier research in physics under extreme strong-field conditions. This includes compact accelerators, high-brightness radiation sources, nonlinear strong-field quantum electrodynamics, as well as the production and detection of axion dark matter based on intense lasers. Over the past decade, Shanghai Jiao Tong University has carried out systematic theoretical, simulation and experimental research in this field, and has successively built a relativistic plasma research platform based on a single-beam hundred-terawatt-level laser and an extreme relativistic plasma research platform based on a dual-beam hundred-terawatt-level laser with high-precision spatiotemporal synchronization. In this paper, we present the layout, key parameters and characteristics of the newly commissioned dual-beam Chongming Laser-plasma Experimental Facility (CLEF), and highlight both completed and ongoing scientific activities, including the studies on laser-solid high-order harmonic generation, laser-plasma wakefield acceleration, nonlinear Compton scattering, and the production and detection of axion dark matter driven by intense lasers. The completion and operation of this facility will provide an essential supporting platform for experimental research in the field of extreme relativistic plasma physics.
2026, 38: 031004.
doi: 10.11884/HPLPB202638.250382
Abstract:
Background Purpose Methods Results Conclusions
Ultrashort and ultraintense laser-driven plasma X-ray sources offer femtosecond pulse durations, intrinsic spatiotemporal synchronization, compactness, and cost-effectiveness, serving as an important complement to traditional large-scale light sources and providing novel experimental tools for ultrafast dynamics research.
Built upon the Synthetic Extreme Condition User Facility (SECUF), the first open-access user experimental station in China based on high-power femtosecond lasers was established to deliver various types of ultrafast radiation sources, supporting studies on ultrafast material dynamics and frontier strong-field physics.
The station is equipped with a dual-beam titanium-sapphire laser system (3 TW/100 Hz and PW/1 shot/min) and multiple beamlines with multifunctional target chambers. Through interactions between the laser and solid targets, gas targets, or plasmas, various ultrafast light sources—such as Kα X-ray, Betatron radiation, and inverse Compton scattering—are generated. Platforms for strong-field terahertz pump–X-ray probe (TPXP) experiments and tabletop epithermal neutron resonance spectroscopy have also been developed.
A highly stable ultrafast X-ray diffraction and TPXP platform was successfully established, enabling direct observation of strong-field terahertz-induced phase transition in VO2. The world’s first tabletop high-resolution epithermal neutron resonance spectroscopy device was developed. On the PW beamline, hundred-millijoule-level intense terahertz radiation, efficient inverse Compton scattering, and high-charge electron beams were achieved.
Integrating high-performance lasers, diverse radiation sources, and advanced diagnostic platforms, this experimental station provides a flexible and efficient comprehensive facility for ultrafast science, promising to advance ultrafast dynamics research toward broader accessibility and more cutting-edge directions.
2026, 38: 031005.
doi: 10.11884/HPLPB202638.250407
Abstract:
High-intensity laser technology, based on chirped pulse amplification, produces extreme optical fields on ultrashort timescales, providing a powerful platform for studying strong-field quantum electrodynamics, laser-plasma interactions, and extreme nuclear environments. This review summarizes the major progress made by the Laser Nuclear Physics Research Team at the Department of Nuclear Physics, China Institute of Atomic Energy, in developing petawatt-class laser systems, theoretical modeling, diagnostic techniques, and applications in nuclear science and industry. The team successfully commissioned a 100 TW ultrafast ultra-intense laser facility in 2023, featuring advanced high-contrast pulse shaping through cross-polarized wave generation and spectral broadening techniques. Additional innovations include thermally optimized eye-safe micro-lasers with improved bonding structures. Theoretical efforts used particle-in-cell simulations to enhance ion acceleration via Coulomb explosion in multilayer targets, achieving high-quality quasi-monoenergetic proton beams under optimized dual-pulse configurations. A novel approach for generating bright circularly polarized γ-rays was proposed, exploiting vacuum dichroism-assisted vacuum birefringence effects. Diagnostic advancements involved refined Nomarski interferometry for precise gas-jet target profiling and fission-source-gated methods for accurate neutron detector calibration. Key applications encompass plasma-based measurements of astrophysical nuclear reaction factors, vortex γ-photon manipulation of nuclear multipole resonances, laser-driven flyer acceleration for high-pressure equation-of-state studies, and enhanced laser-induced breakdown spectroscopy for trace element monitoring in nuclear facilities. These achievements facilitate simulation of stellar nuclear synthesis, advanced radiation sources, materials testing under extreme conditions, and nuclear safety monitoring, laying the foundation for future compact, high-repetition-rate laser systems in energy security and frontier nuclear research.
High-intensity laser technology, based on chirped pulse amplification, produces extreme optical fields on ultrashort timescales, providing a powerful platform for studying strong-field quantum electrodynamics, laser-plasma interactions, and extreme nuclear environments. This review summarizes the major progress made by the Laser Nuclear Physics Research Team at the Department of Nuclear Physics, China Institute of Atomic Energy, in developing petawatt-class laser systems, theoretical modeling, diagnostic techniques, and applications in nuclear science and industry. The team successfully commissioned a 100 TW ultrafast ultra-intense laser facility in 2023, featuring advanced high-contrast pulse shaping through cross-polarized wave generation and spectral broadening techniques. Additional innovations include thermally optimized eye-safe micro-lasers with improved bonding structures. Theoretical efforts used particle-in-cell simulations to enhance ion acceleration via Coulomb explosion in multilayer targets, achieving high-quality quasi-monoenergetic proton beams under optimized dual-pulse configurations. A novel approach for generating bright circularly polarized γ-rays was proposed, exploiting vacuum dichroism-assisted vacuum birefringence effects. Diagnostic advancements involved refined Nomarski interferometry for precise gas-jet target profiling and fission-source-gated methods for accurate neutron detector calibration. Key applications encompass plasma-based measurements of astrophysical nuclear reaction factors, vortex γ-photon manipulation of nuclear multipole resonances, laser-driven flyer acceleration for high-pressure equation-of-state studies, and enhanced laser-induced breakdown spectroscopy for trace element monitoring in nuclear facilities. These achievements facilitate simulation of stellar nuclear synthesis, advanced radiation sources, materials testing under extreme conditions, and nuclear safety monitoring, laying the foundation for future compact, high-repetition-rate laser systems in energy security and frontier nuclear research.
2026, 38: 031006.
doi: 10.11884/HPLPB202638.250412
Abstract:
The emergence and rapid advancement of ultrafast and ultraintense lasers have created unprecedented extreme physical conditions and novel experimental methods, significantly deepening and expanding our understanding of the laws governing the objective world. These developments have greatly promoted innovation in basic and frontier interdisciplinary fields as well as strategic high technology areas. Particle acceleration using the interaction of ultrafast and ultraintense lasers with plasmas is regarded as a next-generation technology for accelerators and radiation sources. It offers the potential to shrink the footprint of conventional accelerator facilities by two orders of magnitude. This dramatic reduction in size greatly expands the applicability of accelerator and radiation source technologies in industry, national defense, medicine, and scientific research, enabling transformative possibilities such as precision nondestructive testing of critical components, ultralow dose and high precision tumor diagnostics, novel low damage radiotherapy methods, and tabletop ultrafast light sources. The ultrafast and ultraintense laser platform at Zhengzhou University introduced in this paper is precisely such a next-generation facility dedicated to advanced laser accelerator research and applications. In addition, this article provides a systematic review of the significant progress achieved by Zhengzhou University in recent years in strong-field physics and advanced accelerator science.
The emergence and rapid advancement of ultrafast and ultraintense lasers have created unprecedented extreme physical conditions and novel experimental methods, significantly deepening and expanding our understanding of the laws governing the objective world. These developments have greatly promoted innovation in basic and frontier interdisciplinary fields as well as strategic high technology areas. Particle acceleration using the interaction of ultrafast and ultraintense lasers with plasmas is regarded as a next-generation technology for accelerators and radiation sources. It offers the potential to shrink the footprint of conventional accelerator facilities by two orders of magnitude. This dramatic reduction in size greatly expands the applicability of accelerator and radiation source technologies in industry, national defense, medicine, and scientific research, enabling transformative possibilities such as precision nondestructive testing of critical components, ultralow dose and high precision tumor diagnostics, novel low damage radiotherapy methods, and tabletop ultrafast light sources. The ultrafast and ultraintense laser platform at Zhengzhou University introduced in this paper is precisely such a next-generation facility dedicated to advanced laser accelerator research and applications. In addition, this article provides a systematic review of the significant progress achieved by Zhengzhou University in recent years in strong-field physics and advanced accelerator science.
2026, 38: 031007.
doi: 10.11884/HPLPB202638.260024
Abstract:
Gamma rays, as electromagnetic waves with extremely high energy and exceptional penetrating power, play an irreplaceable role in numerous frontier fields including nuclear physics, astrophysics, high-energy physics, healthcare, and materials science. Advancements in ultra-intense, ultra-short laser technology have enabled breakthrough progress in laser-driven novel gamma-ray sources. Schemes based on laser-plasma interactions can generate high-brightness, collimated femtosecond-scale ultra-short pulse gamma rays, while also exhibiting significant advantages in compact device design. This paper systematically analyzes the physical mechanisms of laser-driven gamma radiation in the range of hundreds of keV to tens of MeV. It focuses on the characteristics of three primary generation mechanisms: inverse Compton scattering, bremsstrahlung, and betatron radiation. The paper reviews major research advances in China within this field and diagnostic techniques. Research indicates that by optimizing laser-matter interaction parameters, the brightness, pulse width, and energy spectrum characteristics of gamma rays can be effectively controlled.
Gamma rays, as electromagnetic waves with extremely high energy and exceptional penetrating power, play an irreplaceable role in numerous frontier fields including nuclear physics, astrophysics, high-energy physics, healthcare, and materials science. Advancements in ultra-intense, ultra-short laser technology have enabled breakthrough progress in laser-driven novel gamma-ray sources. Schemes based on laser-plasma interactions can generate high-brightness, collimated femtosecond-scale ultra-short pulse gamma rays, while also exhibiting significant advantages in compact device design. This paper systematically analyzes the physical mechanisms of laser-driven gamma radiation in the range of hundreds of keV to tens of MeV. It focuses on the characteristics of three primary generation mechanisms: inverse Compton scattering, bremsstrahlung, and betatron radiation. The paper reviews major research advances in China within this field and diagnostic techniques. Research indicates that by optimizing laser-matter interaction parameters, the brightness, pulse width, and energy spectrum characteristics of gamma rays can be effectively controlled.
2026, 38: 031008.
doi: 10.11884/HPLPB202638.250380
Abstract:
Inverse Compton scattering (ICS) is a fundamental physical process involving an energy exchange between photons and electrons. ICS light sources, generated by collision between relativistic electron beams and intense laser pulses, offer high-brightness, energy-tunable, and short-pulsed X-rays or gamma-rays, which are supporting diverse scientific research and applications worldwide today. This paper aims to review the current technological status and future development prospects of ICS light sources, which are categorized into three evolutionary phases. The first phase, incoherent Inverse Compton scattering (InICS), is a mature foundational technology for most existing ICS light sources and has been widely applied in various fields. The second phase, coherent inverse Compton scattering (CoICS), enhances radiation brightness and beam quality through coherent interactions between electron and photon beams, with key technical approaches including periodic photon structures and periodic electron structures. The third phase, stimulated inverse Compton scattering (StICS), achieves nonlinear enhancement of scattering intensity via stimulated emission amplification, analogous to free-electron lasers (FEL), and holds promise for ultra-high brightness radiation. In this paper, a systematic analysis of the principles, key steps, and technical challenges of each phase is provided. Furthermore, numerical simulations demonstrate that periodic electron structures induced by optical fields can achieve significant coherent enhancement, producing high-quality beams with smaller energy spread and angular divergence. It is envisioned that with advancements in high-intensity short-pulse laser technology, flying focus, and high-current short-pulse electron acceleration, CoICS and StICS are expected to develop rapidly, providing superior brightness and beam quality in the ultraviolet to soft X-ray bands, and opening new avenues for related scientific research and industrial applications.
Inverse Compton scattering (ICS) is a fundamental physical process involving an energy exchange between photons and electrons. ICS light sources, generated by collision between relativistic electron beams and intense laser pulses, offer high-brightness, energy-tunable, and short-pulsed X-rays or gamma-rays, which are supporting diverse scientific research and applications worldwide today. This paper aims to review the current technological status and future development prospects of ICS light sources, which are categorized into three evolutionary phases. The first phase, incoherent Inverse Compton scattering (InICS), is a mature foundational technology for most existing ICS light sources and has been widely applied in various fields. The second phase, coherent inverse Compton scattering (CoICS), enhances radiation brightness and beam quality through coherent interactions between electron and photon beams, with key technical approaches including periodic photon structures and periodic electron structures. The third phase, stimulated inverse Compton scattering (StICS), achieves nonlinear enhancement of scattering intensity via stimulated emission amplification, analogous to free-electron lasers (FEL), and holds promise for ultra-high brightness radiation. In this paper, a systematic analysis of the principles, key steps, and technical challenges of each phase is provided. Furthermore, numerical simulations demonstrate that periodic electron structures induced by optical fields can achieve significant coherent enhancement, producing high-quality beams with smaller energy spread and angular divergence. It is envisioned that with advancements in high-intensity short-pulse laser technology, flying focus, and high-current short-pulse electron acceleration, CoICS and StICS are expected to develop rapidly, providing superior brightness and beam quality in the ultraviolet to soft X-ray bands, and opening new avenues for related scientific research and industrial applications.
2026, 38: 031009.
doi: 10.11884/HPLPB202638.250384
Abstract:
The rapid advancement of ultra-short and ultra-intense laser technology has established laser-plasma acceleration as a premier approach for generating GeV-level electron beams and high-quality radiation sources. Among these, Betatron radiation—emitted as electrons oscillate transversely in plasma channels—has emerged as a unique source characterized by its femtosecond pulse duration, micron-scale source size, and high peak brightness. It holds significant potential in high-energy-density physics, materials science, and ultrafast imaging. This review systematically outlines the physical principles and reviews the latest research progress of Betatron radiation generated via two core mechanisms: laser wakefield acceleration (LWFA) and direct laser acceleration (DLA). A detailed comparison reveals that while the LWFA scheme excels in producing highly collimated, high-energy photons with superior brilliance, the DLA mechanism within near-critical-density plasmas offers a different trade-off. Although DLA generates a significantly larger number of electrons and a higher photon flux, these are characterized by lower photon energies and a wider angular spread. Consequently, the divergence of the emitted X rays typically reaches hundreds of milliradians, which limits the overall brilliance. The review concludes that the future of Betatron radiation lies in enhancing repetition rates and achieving active control over radiation parameters. Developing hybrid schemes and structured targets offer potential to overcome the trade-off between high flux and high brilliance, guiding future experiments at large-scale facilities.
The rapid advancement of ultra-short and ultra-intense laser technology has established laser-plasma acceleration as a premier approach for generating GeV-level electron beams and high-quality radiation sources. Among these, Betatron radiation—emitted as electrons oscillate transversely in plasma channels—has emerged as a unique source characterized by its femtosecond pulse duration, micron-scale source size, and high peak brightness. It holds significant potential in high-energy-density physics, materials science, and ultrafast imaging. This review systematically outlines the physical principles and reviews the latest research progress of Betatron radiation generated via two core mechanisms: laser wakefield acceleration (LWFA) and direct laser acceleration (DLA). A detailed comparison reveals that while the LWFA scheme excels in producing highly collimated, high-energy photons with superior brilliance, the DLA mechanism within near-critical-density plasmas offers a different trade-off. Although DLA generates a significantly larger number of electrons and a higher photon flux, these are characterized by lower photon energies and a wider angular spread. Consequently, the divergence of the emitted X rays typically reaches hundreds of milliradians, which limits the overall brilliance. The review concludes that the future of Betatron radiation lies in enhancing repetition rates and achieving active control over radiation parameters. Developing hybrid schemes and structured targets offer potential to overcome the trade-off between high flux and high brilliance, guiding future experiments at large-scale facilities.
2026, 38: 031010.
doi: 10.11884/HPLPB202638.250371
Abstract:
High harmonic generation (HHG) and attosecond pulses driven by relativistically intense lasers interacting with solid-density plasma mirrors constitute a vital pathway for realizing high-brightness, short-wavelength, ultrafast coherent light sources and exploring extreme strong-field physics. In recent years, benefiting from the rapid development of laser technology, the precise control over light field degrees of freedom, such as amplitude, phase, and polarization, has spurred the emergence of structured light fields. Structured light fields significantly enrich the methods for controlling laser-matter interaction and broaden its scope of applications. This article aims to review the latest progress in controlling relativistic laser-plasma HHG and attosecond pulses using structured light fields. The work specifically discusses methods for characteristic control and the physical mechanisms of HHG driven by novel structured light fields, including polarization structures (e.g., circularly polarized light, vector beams), phase structures (e.g., spatial vortex beams, spatiotemporal vortex beams), and amplitude structures (e.g., Bessel beams, Airy beams), with the goal of providing new perspectives for research on novel light sources based on strong-field laser-plasma interactions.
High harmonic generation (HHG) and attosecond pulses driven by relativistically intense lasers interacting with solid-density plasma mirrors constitute a vital pathway for realizing high-brightness, short-wavelength, ultrafast coherent light sources and exploring extreme strong-field physics. In recent years, benefiting from the rapid development of laser technology, the precise control over light field degrees of freedom, such as amplitude, phase, and polarization, has spurred the emergence of structured light fields. Structured light fields significantly enrich the methods for controlling laser-matter interaction and broaden its scope of applications. This article aims to review the latest progress in controlling relativistic laser-plasma HHG and attosecond pulses using structured light fields. The work specifically discusses methods for characteristic control and the physical mechanisms of HHG driven by novel structured light fields, including polarization structures (e.g., circularly polarized light, vector beams), phase structures (e.g., spatial vortex beams, spatiotemporal vortex beams), and amplitude structures (e.g., Bessel beams, Airy beams), with the goal of providing new perspectives for research on novel light sources based on strong-field laser-plasma interactions.
2026, 38: 031011.
doi: 10.11884/HPLPB202638.250468
Abstract:
Ultra-short and ultra-intense mid-infrared laser pulses hold unique application in fields such as strong-field physics, ultrafast chemistry, environmental monitoring, and biomedicine biomedical applications. Particularly in strong-field physics research, ultra-short and ultra-intense mid-infrared pulses provide a new wavelength scale distinct from the conventional near-infrared range, enabling the exploration of novel physics in the interaction between ultra-intense lasers and matter. However, due to the damage thresholds of traditional laser crystals and nonlinear crystals, the generation of high-energy, single-cycle mid-infrared light sources has long been a significant challenge in ultrafast laser technology. In recent years, utilizing plasma as a nonlinear optical medium, the generation of ultra-short and ultra-intense mid-infrared pulses through photon deceleration process based on laser wakes has emerged as a new research direction in laser-plasma physics. This paper systematically reviews the fundamental principles, numerical simulations, experimental progress, and future application prospects surrounding this physical mechanism of plasma photon deceleration.
Ultra-short and ultra-intense mid-infrared laser pulses hold unique application in fields such as strong-field physics, ultrafast chemistry, environmental monitoring, and biomedicine biomedical applications. Particularly in strong-field physics research, ultra-short and ultra-intense mid-infrared pulses provide a new wavelength scale distinct from the conventional near-infrared range, enabling the exploration of novel physics in the interaction between ultra-intense lasers and matter. However, due to the damage thresholds of traditional laser crystals and nonlinear crystals, the generation of high-energy, single-cycle mid-infrared light sources has long been a significant challenge in ultrafast laser technology. In recent years, utilizing plasma as a nonlinear optical medium, the generation of ultra-short and ultra-intense mid-infrared pulses through photon deceleration process based on laser wakes has emerged as a new research direction in laser-plasma physics. This paper systematically reviews the fundamental principles, numerical simulations, experimental progress, and future application prospects surrounding this physical mechanism of plasma photon deceleration.
2026, 38: 031012.
doi: 10.11884/HPLPB202638.250387
Abstract:
Ultrafast intense laser pulse possesses the characteristics of ultrafast time domain and high peak power. With the rapid development of laser technology, its pulse repetition rate has been gradually increased as well. This kind of repetitive high-power femtosecond laser provides the human beings the unprecedented extreme physical conditions in ultrafast time and ultrahigh intensity field, providing new opportunities, means and directions for driving frontier basic science and cross-application research, such as the generation of novel ultrafast particle beam and intense pulse radiation source. In this paper, we will mainly introduce the newly-built experimental platform developed by the ultrafast light physics team of Shanghai Normal University based on the repetitive high-power femtosecond laser system. The recent research progress on the generation of gas high-order harmonics, intense terahertz radiation sources, high-brightness ultrafast electron beam and their relevant practical applications are all included, along with the resume of the main progress and future prospect in these frontier physics.
Ultrafast intense laser pulse possesses the characteristics of ultrafast time domain and high peak power. With the rapid development of laser technology, its pulse repetition rate has been gradually increased as well. This kind of repetitive high-power femtosecond laser provides the human beings the unprecedented extreme physical conditions in ultrafast time and ultrahigh intensity field, providing new opportunities, means and directions for driving frontier basic science and cross-application research, such as the generation of novel ultrafast particle beam and intense pulse radiation source. In this paper, we will mainly introduce the newly-built experimental platform developed by the ultrafast light physics team of Shanghai Normal University based on the repetitive high-power femtosecond laser system. The recent research progress on the generation of gas high-order harmonics, intense terahertz radiation sources, high-brightness ultrafast electron beam and their relevant practical applications are all included, along with the resume of the main progress and future prospect in these frontier physics.
2026, 38: 031013.
doi: 10.11884/HPLPB202638.250352
Abstract:
Background Purpose Methods Results Conclusions
Electromagnetic pulses generated in high-power laser–solid interactions can cause serious electromagnetic interference and threaten diagnostic systems, making their mechanism study essential.
This work aims to investigate the characteristics and generation mechanisms of electromagnetic pulses induced by picosecond and nanosecond laser irradiation on solid targets.
Experiments were carried out on the Shenguang II upgrade laser facility. The temporal waveforms and frequency spectra of the emitted electromagnetic fields were measured under various pulse durations, laser energies, and irradiation geometries.
For picosecond laser irradiation, the electromagnetic pulses mainly originated from the neutralization current flowing through the target mount, and the peak electric field increased nearly linearly with laser energy. In the nanosecond experiments, the electromagnetic pulse intensity was lower, with the electric field oscillation decaying rapidly and a quasi-DC component observed. Using only the upper eight nanosecond beams produced stronger pulses than sixteen-beam irradiation, showing a modulation. In the combined picosecond and nanosecond laser experiment, the electromagnetic pulse peak generated by the picosecond laser was significantly reduced, which is attributed to the large-scale plasma formed by the nanosecond laser.
These findings clarify the generation behavior of electromagnetic pulses and provide references for mitigating electromagnetic interference in high-power laser experiments.
Study on manipulation mechanism of polarized positrons in nonlinear Breit-Wheeler scattering process
2026, 38: 031014.
doi: 10.11884/HPLPB202638.250410
Abstract:
Background Purpose Methods Results Conclusions
Polarized positron beams are vital probes in fundamental physics. Generating them via the nonlinear Breit-Wheeler process in laser fields is a promising new approach, but control over the positron polarization requires further understanding.
This study investigates how laser and γ-photon parameters control the final polarization of positrons in this process.
Within strong-field QED, we fully include all particle spins and the laser pulse’s finite envelope. Systematic calculations are performed for various laser intensities, γ-photon energies, and polarization configurations.
Key findings are: (1) No positron polarization arises with linearly polarized lasers and γ-photons. (2) When only one is circularly polarized, it dominates the positron polarization, which decreases with higher laser intensity or γ-photon energy. (3) When both are circularly polarized, γ-photons dominate high-energy positron polarization, while both sources co-determine low-energy positron polarization, with laser intensity playing a stronger regulatory role.
These results clarify the dominant factors for positron polarization, providing a key theoretical basis for designing optimized laser-driven polarized positron sources.
2026, 38: 031015.
doi: 10.11884/HPLPB202638.250101
Abstract:
Background Purpose Methods Results Conclusions
The intense electron beam-plasma system serves as an important platform for investigating beam-plasma interactions. Research in this field focuses on the design of electron beam window and the transport characteristics of electron beam in plasma.
The study aims to design and evaluate an electron beam window with excellent comprehensive performance, and to investigate the physical mechanisms underlying the focusing and transmission of intense annular electron beams in plasma.
Finite element analysis and Monte Carlo simulations were employed to compare and evaluate the mechanical, thermal, and transmission properties of candidate window materials. Theoretical analysis and particle-in-cell (PIC) simulations were used to study the self-focusing transmission behavior of intense annular electron beams in plasma.
The TC4 titanium alloy window with a thickness of only 0.04 mm was found sufficient to withstand a pressure differential of 10 kPa. It achieved an energy transmission efficiency exceeding 90% while maintaining controllable temperature variations. The physical mechanism of self-focusing transmission of intense annular electron beams in plasma under conditions of 500 kV and 20 kA was revealed, clarifying the relationship between the focusing transmission period of the electron beam and the plasma density. Furthermore, an equivalent relationship between plasma density and magnetic field was established based on the correspondence between the plasma oscillation period and the electron beam cyclotron period.
The research demonstrates that TC4 titanium alloy is a suitable material for the electron beam window, offering high transmission efficiency and structural stability. It also elucidates the self-focusing transmission mechanism of intense annular electron beams in plasma and establishes a periodic equivalent relationship between plasma and magnetic fields for electron beam transport.
