Just Accepted manuscripts are peer-reviewed and accepted for publication. They are posted online prior to technical editing formatting for publication and author proofing.
Display Method:
Optimization and realization of low hybrid current drive cathode high voltage power supply system
Rui Junhui, Gao Zongqiu, Guo Fei, Huang Yiyun, Zhang Jian
Accepted Manuscript  doi: 10.11884/HPLPB202133.200152
[Abstract](1) [PDF 1247KB](0)
The 4.6 GHz low hybrid current drive (LHCD) system is an important part in the EAST tokamak auxiliary heating system. Its cathode high voltage dc power supply is based on pulse stepped modulation (PSM) technology. 64 DC modules are used to output 50 kV dc voltage in series. As the modulation frequency of PSM single module is 50 Hz, the regulation speed of system is limited. In the face of the interference caused by the voltage fluctuation of the network side in the actual operation, the power supply cannot make more rapid response and feedback regulation. It leads to large fluctuation of the output voltage and affects the output performance. In order to improve the regulation speed and anti-interference capability of system, the high-frequency PSM module with 1 kHz modulation frequency capability was designed to replace some of the original low-frequency modules. The fluctuation of output voltage was suppressed by the rapid regulation capability of the high frequency module. The experimental results show that the output voltage fluctuation of the upgraded power supply is reduced by 58%, which better meets the control requirements of klystron for voltage accuracy and stability, and guarantees the reliability of the system operation.
Application of coulomb collision cross-section in the particle-in-cell of plasma
Song Mengmeng, Zhou Qianhong, Sun Qiang, Yang Wei, Dong Ye
Accepted Manuscript  doi: 10.11884/HPLPB202133.210179
[Abstract](7) [PDF 1715KB](0)
In the particle-in-cell of plasma, TA and Nanbu models have been widely used for Coulomb collision. Both of the models require all particles to collide. In this paper, a cross-section-based method is introduced to give a probability of Coulomb collision for each particle pair and accelerate the computation. To test this method, the relaxations of an electron gas due to e-e collisions were simulated. Compared the simulated with the theoretical values of velocity distribution function, electron temperature, the ratio of electron temperature in x, y direction to electron temperature, the accuracy of the cross-section-based method was verified. The calculation efficiency of this method can be improved by more than 40% than the TA model at the same small time step. Furthermore, at a large time step, the simulations show agreement with the theoretical solutions, the efficiency also improved than the Nanbu model. The simulation about the equilibration of electron and ion temperature showed that this method is also suitable for e-i collisions. Therefore in the acceleration of simulating Coulomb collision, this method has two advantages as follows, the first is a small number of particles to collision within a step, and the second is suitable for large time steps.
Design of high-power and wide-band G-band third harmonic amplifier
Li Ya’nan, Liu Shishuo, Cai Jun
Accepted Manuscript  doi: 10.11884/HPLPB202133.200251
[Abstract](6) [PDF 1104KB](0)
In order to meet the demand of high-power and wide-band signal sources for G-band vacuum electronic devices, the research on G-band third harmonic amplifier is carried out. The amplifier utilizes the third harmonic current in the nonlinear beam-wave interaction of E-band TWT, and realizes G-band electromagnetic wave amplification by cascading harmonic interaction section. The design scheme of high performance and practical G-band wide-band high-power source adopts folded waveguide slow wave structure with modified circular bends, and the G-band third harmonic amplifier is simulated and optimized by using the microwave tube simulator package (MTSS) software. The result shows that the device can obtain harmonic output power greater than 3.6 W in the range of 15 GHz, conversion gain>33.3 dB, and electronic efficiency>0.36%. Compared with other miniaturized Terahertz radiation sources in this band, it has superior performance in terms of output power and bandwidth, which provides a design basis for the subsequent research of G-band third harmonic amplifier.
Analysis of spacecraft charging onset using secondary electron yield
Fang Qingyuan, Wang Tong, Ji Qizheng, Feng Na, Liu Weidong
Accepted Manuscript  doi: 10.11884/HPLPB202133.200149
[Abstract](6) [PDF 876KB](0)
The interaction between space plasma and spacecraft results into the onset of spacecraft surface charging and the resultant electrostatic discharging events. The computation of spacecraft surface charging is commonly accomplished using the secondary electron yield of spacecraft surface irradiated by mono-energetic electrons. In order to depict the charging environment more precisely and obtain the more reliable computation results, focusing the spacecraft charging problem under the worst charging condition and taking into accounts the double-maxwellian plasma distribution, the threshold equation controlling the onset charging is derived based on the averaged secondary electron yield. This equation is useful to analyze spacecraft charging under the condition of election irradiation with a continuous energy spectrum. Besides, the adoption of double-maxwellian plasma distribution could better model the space plasma condition in the case of magnetospheric substorm. By theoretical analysis, the ambient plasma is divided into two typical situations according to the charging characteristics of spacecraft surface charging. Through simulation computation, the trend of spacecraft surface charging versus plasma parameters fluctuations is obtained for these two typical situations. Results show that higher electron temperature corresponds to more severe charging with higher negative potential, meanwhile, the density ratio of the two electron components in double-maxwellian plasma distribution plays an important role in spacecraft surface charging. The obtained conclusions could provide useful reference for the quantitative analysis of spacecraft surface severe charging events.
Study on damage effects of lightning electromagnetic pulse on typical airborne GPS module
Zhang Wanli, Shi Yunlei, He Yong, Shen Jie, Pan Xuchao, Fang Zhong, Chen Hong
Accepted Manuscript  doi: 10.11884/HPLPB202133.200264
[Abstract](16) [PDF 1969KB](1)
In order to study the damage effects of lightning electromagnetic pulses on the UAV airborne GPS module, the understanding of the transient interference, permanent damage process and the damage threshold of GPS modules by lightning electromagnetic pulses was obtained, through a combination of simulation and experimental analysis. Based on the analysis results of lightning current, CST was used to simulate the complex electromagnetic field and coupling voltage on the GPS cable. The data communication ports of the typical airborne GPS module had been subjected to a lightning pulse injection test. The research results show that: with the continuous enhancement of the injected lightning pulse, the degree of influence on the GPS output waveform continues to increase. And finally, the function to transmit position information was lost and physical damage occurred. The lightning impulse damage threshold of the GPS data input port is 314.5 V; the lightning impulse damage threshold of the GPS data output port is 235.2 V.
Electromagnetic wave transmission enhancement effect in non-uniform collision plasma
Nie Yong, Yan Eryan, Yao Hao, Huang Nuoci, Chen Zhiguo, Zheng Qianglin, Bao Xiangyang, Hu Haiying
Accepted Manuscript  doi: 10.11884/HPLPB202133.200233
[Abstract](8) [PDF 1367KB](4)
The effect of plasma on the transmission properties of electromagnetic waves and its application have always been one of the key research directions of electromagnetic theory and technology and plasma physics. The enhancement effect of collision plasma on electromagnetic waves is a classic subject of the interaction between electromagnetic waves and plasma. Based on the transmission characteristics of electromagnetic waves in the medium, this paper takes plasma as a special medium, and carries out experimental, theoretical and simulation studies on the transmission characteristics of high power microwave (HPM) atmospheric plasma and a certain range of electromagnetic waves under certain experimental conditions. The study found that the plasma formed by the S-band HPM under a vacuum of 50 Pa has a great influence on the electromagnetic wave transmission characteristics of different frequencies, and the electromagnetic wave transmission signal enhancement effect occurs regularly within a certain frequency range. A series of transmission waveforms of continuous electromagnetic waves of different frequencies passing through the HPM plasma area were obtained, and the waveforms were normalized. At 32.4 GHz, the transmission coefficient of continuous electromagnetic waves passing through the plasma area with or without plasma is about twice as high difference. A simulation model was established, and the transmission coefficient distribution curve in the range of 31.5-32.5 GHz was obtained. The electromagnetic wave passing through the plasma showed a transmission enhancement effect, and at some frequency points, there was a transmission enhancement of about 1.9 times. The acquisition of the research results provides important technical support for the application of plasma in stealth, emergency communications, and black barrier communications.
Magnet support plinths of advanced light source
Li Chunhua, Wang Zihao, Zhou Ningchuang, Dong Lan, Wang Xiaolong, Qu Huamin
Accepted Manuscript  doi: 10.11884/HPLPB202133.200201
[Abstract](14) [PDF 1085KB](4)
As the installation foundation of magnet support, the plinth is critical for the stability of the whole support unit. Different fabrication and installation processes make significant differences in performance. Based on the high requirements of advanced synchrotron light source for the mechanical stability of magnets, the plinth installation pouring experiment was carried out. Several concrete construction techniques commonly applied in practice were tested with the plinths of uniform shape and size. The natural frequency was measured one by one by hammering method and stability was evaluated. It is concluded from the test result that grouting can effectively improve the stability of the plinth and the epoxy-based grouting shows better performance in stability than that of cement-based grouting. Based on the natural frequency test result, the influence of the plinth on the system mode is analyzed with the support system of High Energy Photon Source as an example. The experimental results have certain reference value for the plinth design of the similar machine.
Simulation of the solenoid scan method used in overlapping field for thermal emittance measurement
Fan Peiliang, He Xiaozhong, Yang Liu, Wei Tao, Jiang Xiaoguo, Li Yiding, Zhang Xiaoding, Wang Ke, Yang Xinglin
Accepted Manuscript  doi: 10.11884/HPLPB202133.200197
[Abstract](14) [PDF 763KB](0)
In one high repetition frequency X-ray free electron laser (XFEL) equipment, the electron gun and compensate solenoid have special structure in the photoinjector, then the electric field and the magnetic field are overlapping near the cathode. The thermal emittance of the cathode will be measured in the experiment. The solenoid san method which used to measure the thermal emittance is not suitable for the overlapping field, because it is used only when the rms emittance keep constant. For the normalized phase space can avoid the influence of the electric field, so we try to use the solenoid scan method in normalized phase space. We also use simulation code to do some simulation, and finally we find that this method is feasible for the photoinjector, and it will become the guide in the future experiment.
Miniaturized tri-band balanced filter based on a novel asymmetric stepped impedance resonator with self-coupling
Zhang Junjie, Li Jianbing, Zhou Dongfang, Liu Qing, Wang Xian, Zhang Dewei
Accepted Manuscript  doi: 10.11884/HPLPB202032.200153
[Abstract](7) [PDF 1157KB](2)
For the application requirements of high integration and high selectivity of balanced filters, this paper proposes a novel balanced tri-band filter with high selectivity, which is based on an improved asymmetric stepped impedance resonator structure with self-coupling. Firstly, through the differential mode and common mode equivalent circuits of the balanced filter, the resonant characteristics of the resonator structure are specifically analyzed, and the first three resonance modes under the differential mode equivalent circuit are used to form three passbands respectively. In addition, by loading capacitors and resistance elements on the symmetrical surface of the circuit, the suppression of CM signals can be improved without affecting DM signals based on the proposed multimode balanced filter structure and design method, a balanced tri-band filter with passband frequencies of 2.75/4.46/6.21 GHz was designed, processed and tested. The results show that the structure can achieve a compact size and high selection characteristics, and has good common mode rejection characteristics.
Experimental investigation of the package of diode laser chip based on lateral heat flow suppression
Xie Pengfei, Lei Jun, Lv Wenqiang, Gao Songxin, Wang Zhao, Cao Liqiang, Wang Chengqian
Accepted Manuscript  doi: 10.11884/HPLPB202133.200241
[Abstract](13) [PDF 1035KB](3)
In order to improve slow axis beam quality of diode laser (LD) and decrease slow axis divergence angle, a new package named lateral heat flow suppression was designed by the difference in thermal conductivity between air and heat sink. In this paper, the finite element analysis software was used to analyze the temperature distribution with lateral flow suppression package. It showed that diode laser chip soldered on trough heat sink with width W=120 um and length L=4000 um can reduce slow axis divergence angle about 14%, from 12.25° to 10.49°, when working current was 15A. Correspondingly, it can reduce BPP from 5.344 mm·mrad to 4.5763 mm·mrad and the brightness of slow axis is increased about5.5% than before.According to the result, the lateral flow suppression package can weaken higherorder modecausedbythermal lens effect of diode laser so that decrease slow axis divergence angle effectively.
Design of TEM horn antenna based on distributedimpedance end-loading
Yuan Yanning, Feng Qiang, Yi Chaolon, Xi Xiaoli
Accepted Manuscript  doi: 10.11884/HPLPB202032.200198
[Abstract](18) [PDF 1221KB](2)
Based on the consideration of power capacity and aperture matching to extend the low-frequency operating bandwidth, an ultra-wideband TEM horn antenna with a distributed impedance end-loading structure was designed. First, the gradual coaxial-flat balun structure has been optimized, which expands the working bandwidth of the feed structure and improves the feed efficiency. Secondly, the distributed impedance matching design was performed on the exponential TEM horn antenna, and its port characteristics and radiation characteristics were significantly improved. The power pattern and energy pattern were used to evaluate the radiation effect of the antenna. The experimental results show that, compared with the exponential TEM horn antenna, after the distributed impedance matching structure is loaded, the antenna low-frequency bandwidth is widened by 330 MHz, the peak-to-peak value of the antenna main axis radiated electric field is increased by 10%, and the feed efficiency is increased by 17%.
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:
>500 W passively-cooled fiber cladding light stripper
Liu Yu, Li Min, Huang Shan, Wu Wenjie, Feng Xi, Shen Benjian, Song Huaqing, Tao Rumao, Wang Jianjun, Jing Feng
Corrected proofs  doi: 10.11884/HPLPB202032.200182
[Abstract](34) [PDF 1024KB](0)
To realize of passive-cooling high power fiber cladding light stripper, it is important to optimize the thermal management of both the fiber and the package. By using Teflon capillaries to make segmental etching configuration on fiber, using copper as the package material, and optimizing the package structure through finite element thermal simulations, cladding light stripper capable of handling 500 W power was designed and fabricated. It was experimentally verified that the stripping efficiency reached 23.7 dB and the temperature increase rate on the bare fiber of cladding light stripper was as low as 0.007 ℃/W. In addition, at 540 W of power injection, cladding light stripper could work continuously if mounted on water-cooled cold plate, and could work for 50 s each time if mounted on cold plate filled with phase-change material, with the maximum temperature of package being 58.7 ℃ and 80 ℃ respectively. The researches and results could provide valuable information to the design and development of high power fiber lasers.
Fabrication and test of high power fiber Bragg grating with 1080 nm central wavelength
Song Huaqing, Liu Yu, Huang Shan, Feng Xi, Wang Jianjun, Tao Rumao
Corrected proofs  doi: 10.11884/HPLPB202133.200181
[Abstract](35) [PDF 928KB](3)
High power double cladding fiber Bragg grating (FBG) fabrication based on ultraviolet laser and phase mask method was introduced. A pair of chirped FBGs with 1080 nm central wavelength was made. The reflection spectrum bandwidths were 2 nm and 1 nm, respectively. We adopted these FBGs to construct a fiber oscillator. whose output signal power is up to 502 W.
Triggering and anti-interfering technology of diagnostic systems used in Z-pinch experiments
Zhou Shaotong, Huang Xianbin, Ren Xiaodong, Wang Kunlun, Xu Qiang, Zhang Siqun
Corrected proofs  doi: 10.11884/HPLPB202133.200200
[Abstract](21) [PDF 800KB](3)
The pulse power device will produce a strong electromagnetic environment in the process of discharge, which interferes with diagnostic systems in the experiment, leading to their failure to work properly. By selecting, transforming and delaying the time correlated signals, a trigger network has been established for diagnostic instruments in high energy density experiments on an 8 MA pulsed power device. The jitter of time interval between the trigger signal and the X-ray pulse is less than 2 ns, which meets the requirement to synchronize diagnostics with time resolution of nanosecond. Shielding and grounding techniques are used and effectively eliminate the jamming of strong electromagnetic environment and other stray signals produced by the discharge of the device, which also ensure the normal operation of diagnostic instruments and the quality of the experimental data.
Analyses of barrier points of uniform transmission line for CSNS/RCS pulse power supply
Zhai Jun, Chen Yukai, Li Haibo, Zhou Guozhong, Shen Li
Corrected proofs  doi: 10.11884/HPLPB202032.200107
[Abstract](32) [PDF 787KB](1)
By studying the principle of characteristic impedance mismatch of uniform transmission line, it is found that the characteristic impedance mismatch of transmission cable will lead to the distortion of excitation current amplitude of load terminal. The key parameters of main circuit for power supply are analyzed, the amplitude and rise time of the excitation current at the magnet are decreased, when the matching impedance of the uniform transmission line is mismatched. By establishing the equivalent model of barrier point in uniform transmission line, the reflection coefficient at the barrier point of the uniform transmission line is derived. Based on the analysis of series resistance and parallel resistance at the barrier, it is found that the mismatch of transmission line characteristic impedance will lead to the decrease of active power at matching load. It is verified by the breakdown of high voltage cable.
Research progress of high-power waveguide window
Zhang Xue, Wang Tao, Yu Qianqian, Wang Yong
Corrected proofs  doi: 10.11884/HPLPB202133.200257
[Abstract](15) [PDF 2494KB](0)
High-power waveguide window is a critical component of high-power klystron and accelerator. The RF breakdown of the waveguide window always cause the failure of the high-power klystron. In this paper, the research progress of high-power waveguide window in the international vacuum electronics field is introduced. The research status, manufacturing requirement, and RF breakdown mechanism of the classical pill-box window are presented at first. Then the characters of some new type waveguide windows such as the tapered window, travelling wave in ceramic window, mixed-mode window, and over-mode window are summarized. Some breakdown suppression technologies like changing the material character of the window disk, changing the surface configuration of the window disk, using the positive dielectric angle, applying DC electric field or DC magnetic field, changing the waveform of transverse electric field are emphasized at the end.
Development of a neutron monitor based on embedded EPICS
Zhu Wenchao, Lin Hanshang, Zhou Zeran, Jiang Shiping
Corrected proofs  doi: 10.11884/HPLPB202032.200168
[Abstract](33) [PDF 1060KB](4)
Aiming at the radiation protection and safety requirements of HLS-II (HLS-Ⅱ), a neutron monitor based on embedded EPICS was developed for neutron monitoring of radiation field and environment. The control system of HLS-II is based on EPICS (Experimental Physics and Industrial Control System) architecture. In order to reduce the middle link of the radiation monitoring system and improve the reliability of the personal safety chain of HLS-II, a neutron monitor based on embedded EPICS control system was developed. The key component of the neutron monitor-detector is the BF3 proportional counter tube. By adding a 2 kV positive high voltage bias to the weak electrical signal generated by the proportional counter tube, the AC coupling intervenes in the preamplifier for amplification, and then outputs a pulse signal with a fixed width. The signal is counted by the CORTEX-M3 circuit, and then processed by the CORTEX-A8 circuit to publish the data to the local area network. The performance of the developed monitor has been preliminarily tested by using Am-Be neutron source and on-site radiation environment of HLS-II. The results show that the monitor meets the design requirements and can be used for neutron monitoring.
Development of digital self-excited loop in vertical tests of superconducting cavity
Feng Liwen, Wang Fang, Lin Lin, Hao Jiankui
Corrected proofs  doi: 10.11884/HPLPB202032.200216
[Abstract](31) [PDF 1325KB](6)
Vertical tests are very important for superconducting cavity after its post-processing. The aim is to obtain the quality factor versus accelerating gradient curve to evaluate a cavity’s performance. Because of its narrow bandwidth, the superconducting cavity should work stably in the resonant state during the vertical tests. The digital self-excited loop system for the vertical test stand of Peking University is introduced in this paper. The methods of avoiding crosstalk during multi-cell superconducting cavity test were brought out. The influence of deviation from quadruple frequency sampling on amplitude and phase was analyzed. The system is stable and reliable, can effectively distinguish \begin{document}$ {\text{π}} $\end{document} mode from \begin{document}$ 8{\rm{{\text{π}}}}/9 $\end{document} mode of the 1.3 GHz 9-cell superconducting cavity, and solve the problem of mode crosstalk in multi-cell superconducting cavity test.
Design of Q-band wideband linearizer
Li Baojian, Qu Bo, Xia Lei, Han Fei
Corrected proofs  doi: 10.11884/HPLPB202133.200206
[Abstract](19) [PDF 1111KB](0)
At present, China’s Q/V band low orbit satellite internet project is being vigorously carried out, broadband communications are gradually developing. But the domestic linearization technology is generally limited to narrow band, the related research is not mature. Therefore, it is necessary to design broadband linearizer as soon as possible. In this paper, a Q-band linearizer of traveling-wave tube amplifier (TWTA) for satellite communication has been designed using an analog predistortion technique suitable for space environment. Using the new microstrip transmission structure and the Schottky diode, the ultra-wide instantaneous frequency band can be linearized in the millimeter-wave frequency band. The amplitude distortion and phase distortion of TWTA are greatly improved in the 38−43 GHz (5 GHz) instantaneous frequency band. The linearizer has an in-band amplitude gain of about 4.8−7.2 dB and a phase expansion of about 70°−88° in the input power range of −17−13 dBm. Compared with other linearizers of the same type, this linearizer has higher corresponding frequency and can realize stable linearization of TWTA in a wide instantaneous frequency band.
Development of S-band hybrid bunching-accelerating structure prototype
Gao Bin, Pei Shilun, Wang Hui, Zhao Shiqi, Chi Yunlong
Corrected proofs  doi: 10.11884/HPLPB202133.200162
[Abstract](43) [PDF 1239KB](2)
Hybrid bunching-accelerating structure (HBaS) is a novel RF structure integrating a standing-wave(SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure together. This paper presents the design results, including beam dynamic optimization, microwave design and the cold test of the S-band HBaS prototype, and explicates the reason of transverse emittance increasement caused by the hybrid structure. The low RF power results are in good agreement with the RF design. The measured S11 at operation frequency is less than −45 dB, the phase shift deviation is less than ±2° and the bandwidth is more than 5 MHz (VSWR≤1.2). The axis field distribution fully meets the dynamic requirements.
Self-triggering all-solid-state Marx generator
Rao Junfeng, Li Encheng, Wang Yonggang, Jiang Song, Li Zi
Corrected proofs  doi: 10.11884/HPLPB202133.200223
[Abstract](39) [PDF 1488KB](8)
With the wide application of all-solid-state high-voltage pulse generators in the fields of material modification, biomedicine and industry, all-solid-state pulse generators are developing in the direction of miniaturization, intelligence and modularization. To further reduce the volume and cost of the power supply, this paper proposes a positive self-triggering all-solid-state Marx generator topology. It only needs to provide an isolated signal to control the turn-on and turn-off of discharging switch in the first stage, and the gates of the adjacent-stage discharging switches will be automatically charged and discharged through the inter-stage capacitors, so that they turn on and off one by one. This topology makes the driving circuit of the multiple switches in the Marx generators much simpler and does not need to provide a multi-channel driving power supply with isolated power supplies, and also avoids the dynamic and static voltage balancing problems of the switches. Based on this topology, a 17-stage positive polarity Marx generator prototype is built, and the voltage amplitudes and pulse widths are continuously adjustable. It outputs 10 kV positive high-voltage pulses at a repetition frequency of 100 Hz over a 10 kΩ resistive load. The leading edge is approximately 328 ns. The prototype is small in size and stable in work, which verifies the feasibility of this topology.
Principle device and experimental research of surface exposure selective laser melting for metal powder
Wang Chenguang, Shen Xianfeng, Wang Guowei, Wu Hualing, Wu Hongfei, Wang Kaijia, Chen Jinming
Corrected proofs  doi: 10.11884/HPLPB202133.200221
[Abstract](34) [PDF 1422KB](2)
Compared with a point laser scanning method, a surface exposure laser melting has advantages of high forming efficiency and low residual stress, which has become a promising new generation selective laser melting of additive manufacturing technology. In this paper, a principle device platform of new generation surface exposure selective laser melting were developed with a light source of 915 nm diode laser, combined with an electrically addressed reflective pure phase liquid crystal spatial light modulator. Its principle experimental verification of surface exposure selective laser melting were implemented. A sample of surface exposure selective laser melting with a “○”-shaped pattern were obtained by using a low melting point metal powder.
Cover and Contents
Cover and Contents, High Power Laser and Particle Beams, No 11, Vol 32, 2020
Editorial Office
[PDF 6029KB](49)
Inertial Confinement Fusion Physics and Technology
Progress of grazing incidence X-ray micro-imaging diagnosis technology
Xu Jie, Mu Baozhong, Chen Liang, Li Wenjie, Xu Xinye, Wang Xin, Wang Zhanshan, Zhang Xing, Ding Yongkun
2020, 32: 112001.   doi: 10.11884/HPLPB202032.200133
[Abstract](243) [PDF 3121KB](45)
High-precision X-ray imaging diagnosis is the key to understanding the implosion process and revealing unknown physical problems at the ignition scale. X-ray microscope based on grazing incidence reflection, combined with sub-nanometer ultra-smooth spherical or aspherical mirror, can achieve high-resolution imaging with spatial resolution better than 5 μm. This paper introduces the development and application of foreign X-ray microscopic imaging technology in the field of ICF research, highlights the progress of China’s high-resolution X-ray Kirkpatrick-Baez (KB) microscope, multi-channel X-ray KB microscope and large-field X-ray KBA microscope. The research plan for the next stage of ultra-high resolution X-ray microscopic imaging is analyzed. Through continuous technological innovation, China's X-ray microscopic imaging diagnostic capabilities have reached the internationally advanced level.
Progress in high time- and space-resolving diagnostic technique for laser-driven inertial confinement fusion
Wang Feng, Zhang Xing, Li Yulong, Chen Bolun, Chen Zhongjing, Xu Tao, Liu Xincheng, Zhao Hang, Ren Kuan, Yang Jiamin, Jiang Shaoen, Zhang Baohan
2020, 32: 112002.   doi: 10.11884/HPLPB202032.200136
[Abstract](233) [PDF 2229KB](38)
This article reviews the latest developments of high time- and space-resolving diagnostic technique for laser-driven inertial confinement fusion (ICF) in China. Focusing on the needs of hot spot diagnosis with temporal resolution better than 10 ps, spatial resolution better than 10 μm, and energy range of 10−30 keV, we introduce recent progress in optical, X-ray, and nuclear diagnostics, as well as computational imaging. In optical section, we introduce two diagnostics based on the pump detection technique: all-optical scanning, with temporal resolution up to 200 fs, and all-optical framing, with temporal and spatial resolution up to 5 ps and 5 μm respectively. Since the main components are optical, these systems have great potentials to be applied in the strong electromagnetic, ionizing environment of future ICF research. In X-ray section, we introduce a recently developed high-resolution kirkpatrick-Baez (KB) microscope, which adopts the STTS (S and T represent sagittal and tangential directions respectively) configuration and improves the spatial resolution to 3 μm, meeting the current requirements. Besides, we also discuss a developing technology—the drift tube technology, with temporal resolution up to 10 ps. In nuclear section, we mainly introduce the high-resolution recording system of the neutron imaging, with spatial resolution up to 20−25 μm, as well as the progress in the corresponding aiming technique. In addition, we introduce computational imaging, which is a brand new branch attracting growing attention in ICF field. We also emphasize the three dimensional light field imaging technique and compressed ultrafast photography (CUP) technique, and propose their possible applications in ICF field.
Introduction to development of streak and framing cameras
Tian Jinshou
2020, 32: 112003.   doi: 10.11884/HPLPB202032.200119
[Abstract](276) [PDF 1696KB](44)
This paper introduces the significance of the research on ultrafast diagnosis technology, summarizes the history and current situation of streak camera and framing camera, analyzes the technical characteristics and main application fields of several mainstream streak tubes, compares the characteristics of domestic and foreign research and development institutions of ultrafast diagnosis equipment. Finally, it presents the achievements and existing problems of ultrafast diagnosis technology in China as well as a preliminary analysis and discussion on further development in this fied.
Progress of X-ray high-speed photography technology used in laser driven inertial confinement fusion
Cao Zhurong, Wang Qiangqiang, Deng Bo, Chen Tao, Deng Keli, Wang Weirong, Peng Xingyu, Chen Zhongjing, Yuan Zheng, Li Yukun, Wang Peng, Chen Bolun, Wang Feng, He Haien, Li Xingzhu, Xu Zeping, Yang Dong, Yang Jiamin, Jiang Shaoen, Ding Yongkun, Zhang Weiyan
2020, 32: 112004.   doi: 10.11884/HPLPB202032.200099
[Abstract](168) [PDF 1542KB](22)
In the study of laser driven inertial confinement fusion (ICF), the image data obtained through X-ray high-speed photography technology can be used to analyze the spatial and temporal evolution of the plasma with fluid state produced by work and energy transport. The research of X-ray high-speed photography technology has always been an important part of the development of ICF diagnostics. The Laser Fusion Research Center of China Academy of Engineering Physics has made important progresses in the research of X-ray high-speed photography technology in recent years. These advances include: (1) making a success in developing the X-ray camera with 100ps exposure time for Shenguang laser facilities, which has reached the international advanced level as a whole, and is characterised in such aspects as high sensitivity, transmission-type band-pass filtering and miniaturized design; (2) proposing new types of X-ray high-speed photography technologies with 10 ps exposure time such as the micro-sweep gating technology to break the bottleneck of temporal resolution; (3) taking the lead in carrying out theoretical design, technical verification and engineering design of the radiation-hardened X-ray high-speed camera in China; (4) making the efforts on modeling and simulation on target debris and carrying out the special experiments for the first time in China to verify the simulation results.
State of the art and future prospective of high performance streak cameras for laser fusion
Hu Xin, Li Jin, Liu Shenye, Zhang Kunlin, Li Yukun, Wang Feng, Yang Jiamin, Ding Yongkun, Jiang Shaoen, Zhang Xing
2020, 32: 112005.   doi: 10.11884/HPLPB202032.200109
[Abstract](155) [PDF 1447KB](20)
The streak cameras have very important applications in Inertial Confinement Fusion (ICF), including x-ray streak cameras and optical streak cameras. At present, they are still the core diagnostic devices with the highest temporal resolution in this field. This paper introduces the performance and characteristics of two main types of the streak cameras widely used in the field of laser fusion both domestic and international. They are equipped with coaxial electrode double-focus electron optics streak tube and bilamellar electron optics streak tube respectively. In terms of specifications of streak camera, the criteria of dynamic range of streak camera are emphasized, the dynamic range data of today's international high performance streak cameras are presented. The paper also introduces several important research progresses in the development of streak camera technologies, including advanced backlighting ultraviolet fiducial system, neutron radiation tolerant device and gated cathode technology.
Progress in high energy all-solid-state regenerative amplifier
Wu Yuanjun, Gao Yanqi, Hua Yilin, Xie Qingnan, Zheng Quan, Ma Weixin, Sui Zhan
2020, 32: 112006.   doi: 10.11884/HPLPB202032.200089
[Abstract](286) [PDF 1201KB](26)
Among solid-state laser amplifiers, regenerative amplifiers which have the advantages of high gain, good beam quality and simple structure, have been widely concerned and applied. After decades of development , regenerative amplifiers are able to realize pulse energy of several hundred millijoules and average power of several kilowatts in stable operation. The output performance of regenerative amplifiers is determined by properties of gain media, structure of cavity, pump condition, thermal effect and qualities of components. The properties of gain media are the most essential factors. Because of different properties of materials, regenerative amplifiers based on different kinds of materials present different structure and performance. Based on different material systems, the key common problems encountered in the development process of regenerative amplifiers under various systems, as well as several typical types of regenerative amplifiers and their characteristics are introduced. The future development trend of regenerative amplifiers is discussed.
Conceptual design of soft X-ray online calibration system for ICF
Cao Leifeng, Yang Zuhua, Chen Jihui, Wei Lai, Fan Quanping, Chen Yong, Zhang Qiangqiang, Zhou Weimin
2020, 32: 112007.   doi: 10.11884/HPLPB202032.200141
[Abstract](114) [PDF 1710KB](13)
For a long time, the calibration of soft X-ray diagnostic equipment components of ICF research mainly depends on the synchrotron radiation source X-ray metrology station. This kind of device is usually located in a different place from the large laser facility for ICF research, thus it is difficult to meet the real-time field calibration application requirements of ICF’s research soft X-ray components research. In addition, in view of the great difference between the radiation characteristics of synchrotron radiation X-ray and ICF laser plasma X-ray, the calibration results of synchrotron radiation measurement station can not completely measure the response characteristics of components in ICF experiments. In this paper, a kind of monochromatic technology for compact non-harmonic soft X-ray source is introduced. Based on this technology, a monochromatic system of multi energy channel source based on ICF laser plasma X-ray source with homologous, geometric configuration and double beam comparison calibration is developed for on-line calibration of soft X-ray components in ICF applications. The new system is expected to meet the requirements of real-time calibration application of ICF’s soft X-ray components, while the technical characteristics of its calibration beam will be as close as possible to that of the ICF laser plasma X-ray radiation.
Study on X-ray line emission diffraction in inertial confinement fusion and its recent progress
Sun Ao, Shang Wanli, Yang Guohong, Wei Minxi, Li Miao, Che Xingsen, Hou Lifei, Du Huabing, Yang Yimeng, Zhang Wenhai, Yang Dong, Wang Feng, He Haien, Yang Jiamin, Jiang Shaoen, Zhang Baohan, Ding Yongkun
2020, 32: 112008.   doi: 10.11884/HPLPB202032.200129
[Abstract](117) [PDF 1365KB](11)
This paper introduces the relationship between X-ray line emission diagnosis and various physical quantities in the study of inertial confinement fusion, and briefly explains the diagnosis method and principle of X-ray crystal spectrometer. For different types of diagnosis, it introduces the functions and principles of different commonly used types of diffraction crystals. In addition, it introduces a new type of X-ray diagnostic method of multi-cone curved crystals, which has high light collection efficiency and at the same time ensures the delicate coupling of the back-end receiving device and reduces aberrations. Based on the study of the diffraction characteristics of the multi-cone curved crystal, X-Chase, an X-ray arbitrary surface crystal diffraction tracking simulation software, was developed. At the same time, the multi-cone crystal of H and He line emissions on the SG laser facility is utilized to demonstrate the code functions. The numerical simulation results show that the variable cone crystal has a good focusing ability.
Research progress of low-temporal-coherence light frequency conversion technology for high power Nd:glass laser system
Ji Lailin, Zhao Xiaohui, Liu Dong, Xia Lan, Gao Yanqi, Cui Yong, Rao Daxing, Feng Wei, Liu Jiani, Li Xiaoli, Liu Jia, Shi Haitao, Wang Tao, Du Pengyuan, Zhang Tianxiong, Sui Zhan, Ma Weixin, Zhu Jian
2020, 32: 112009.   doi: 10.11884/HPLPB202032.200103
[Abstract](134) [PDF 2203KB](12)
Low temporal coherence pulse can effectively increase the threshold of parametric instabilities in the laser and plasma interaction. However, frequency conversion efficiency is one of the bottlenecks in its engineering application. The characteristics of frequency conversion technologies of various low-coherence pulse for the high-power laser drivers are summarized in this paper, and based on numerical simulations and experiments, application feasibility of partial deuterium DKDP crystals for frequency doubling and tripling of super-luminescent light are analyzed in detail. The results show that 17% deuterium DKDP crystals can be used for efficient frequency doubling of super-luminescent light in neodymium glass systems, and the conversion efficiency can reach about 80%. 10% gradient deuterium DKDP crystals can be used for triple frequency of 5 THz bandwidth.
Recent progress in micro-mesoscopic study of dynamics of plastic deformation based on large-scale laser facilities
Wang Qiannan, Hu Jianbo
2020, 32: 112010.   doi: 10.11884/HPLPB202032.200116
[Abstract](114) [PDF 1551KB](19)
The dynamic response of materials is strongly dependent on the temporal evolution of microstructures. As a comprehensive experimental platform integrating dynamic loading and in-situ diagnostic capability, large-scale laser facilities provide technical support to investigate micro-mesoscopic behaviors of materials under extreme conditions of high temperature, high pressure, and high strain rate. The use of high-power pulsed lasers to explore the response of materials under the pressure of tens of GPa up to several TPa, the time duration of nanoseconds, and the strain rate of 106−1010 s−1 is revealing novel mechanisms of plastic deformation and therefore strength evolution. This unique experimental tool, aided by advanced diagnostics, analysis, and characterization, including X-ray diffraction, absorption and imaging, allows us to make real-time observation on these new regimes with high spatial and temporal resolution. In this paper, we review the progress within the last 20 years in micro-mesoscopic dynamic probing techniques, based on large-scale laser facilities, and their applications in the study of dynamic plasticity and strength. At the end, we discuss the significance of these works to promote the multiscale modeling of the dynamic response of materials.