The focusing method can be used to achieve continuous change of the focal length, so that the optical components at different object distances can be detected online. However, the focusing process is complicated and requires high accuracy of the focusing displacement. Defects of optical components within the depth of field cannot be distinguished, making it difficult to achieve real online detection. Therefore, this paper proposes an online detection method for optical component defects based on camera arrays. First, the imaging model of the camera array is established, and the expressions of digital refocusing and the expressions of spatial resolution are given. Then MATLAB is used to simulate the camera array imaging process and digital refocusing process. Finally, experimental verification was conducted. The camera was driven by a two-dimensional stage to image the surface defects of multiple optical elements at different object distances, and an array camera image was obtained. The digital defect refocusing algorithm was used to obtain the surface defect distribution of optical elements at different object distances information. The experimental results show that the online detection technology of optical component defects based on camera array can simultaneously detect the optical components located in the depth of field range. This method has certain application value in the online detection of optical component defects.

Aiming at the fact that with the increasing output energy of oxygen-iodine chemical lasers in China, one of the main factors limiting the quality of the beam is the misalignment of the optical cavity during the light emission process, a method for self-collimation of optical resonators based on image processing was proposed. This research method uses helium-neon light to pass through the central hole of the concave cavity mirror, and an industrial camera is placed behind the convex cavity mirror to form an interference concentric ring above the screen. Through the image processing methods such as binarization and Hoff circle detection in the OpenCV library, the center coordinates of the interference concentric ring are obtained, and the image is divided into four parts: upper, lower, left, and right. The difference of the number of bright pixels between these four parts is used to estimate the offset state of the interference concentric ring, and then the theoretical criterion for the change of the optical resonator under the cavity condition is obtained. The experimental results show that this method can obtain quite accurate optical resonance cavity misalignment criterion. The misalignment criterion is selected from the difference between the left and right bright pixels of 30 000, and the difference between the upper and lower bright pixels of 45 000.

Magnetized Liner Inertial Fusion (MagLIF) is a new concept of controlled fusion, which combines both advantages of traditional magnetic confinement fusion (MCF) and inertial confinement fusion (ICF). It has promising application potentials because theoretically it can dramatically lower the difficulties in realizing controlled fusion. For purpose of better understandings of MagLIF, we investigate and summarize the main progresses  achieved in this field. This paper will acquaint  researchers with MagLIF research progress in the following domains: theoretical and analytic research, numerical simulations, experimental configurations, measurements and diagnostics, load designs and fabrications, laser driving MagLIF and auto-magnetization target. It will also provide heuristic perspectives for future MagLIF research.

This article intoduces the principle of extended X-ray absorption fine structure(EXAFS) as parameter diagnostic method on large laser facilities, as well as the experiments on SG-III prototype facility for high quality EXAFS. Using glass ball, CH capsule and Au ball as backlighters, through multi-shots accumulation method, EXAFS of Ti in ambient condition with good signal-to-noise ratio were obtained. The experiment results coincide well with the results of the synchrotron radiation experiment, indicating the correctness and reliability of the experimental design. Analysis of the results show the factors affecting the EXAFS spectrum quality are photon counts, spectral resolution, noise and flaws on apparatuses.

Quasi-optical mode converters are usually used in gyrotrons to realize the conversion of high-order cavity mode to Gaussian beam. Using the scalar diffraction theory, the K-S phase-correcting optimization iterative algorithm Geometrical Optics and the least mean square(LMS) algorithm, this paper designs a dual-frequency quasi-optical mode converter with operating frequency of 105 GHz (TE_18,7) and 140 GHz (TE_24,9). According to the simulations results, the conversion efficiencies are 97.3% at 105 GHz and 99.0% at 140 GHz. And the Gaussian contents of the output beam on the window surface are 98.0% at 105 GHz and 99.7% at 140 GHz. This high efficiency dual-frequency quasi-optical mode converter can be used in a MW dual-frequency gyrotron.

Bi-phase modulator is one important component in SLAC energy doubler (SLED) pulse compression systems. Performance parameters such as precision and speed of phase shift have  significant impact on SLED. In this paper, an S-band bi-phase modulator with fast speed and adjustable accuracy is presented. Precision of the phase shifter is related to two parallel varactors, controlled by bias voltage. The simulated results show that the proposed bi-phase modulator has a fast switching speed of 4 ns and a high phase shift accuracy.

This paper analyses the electron emission from cathode stick and multi-beam cathode rod of MBK and investigates the transport efficiency with different radius and drift tube length. The results show that with compact constructure the electron emission from cathode stick and rod under high voltage affect the multi-beam transmission efficiency obviously. Especially, the beam bombing on the wall of tube will degenerate the repetition capacity of multi-beam klystron. To resolve these problem,  a combined magnetic system is designed and fabricated, which can reduce the stick and rod emission by pulling the multi-beam cathode out of the high electric zone. Then a multi-beam diode with combined magnetic system is designed. Calculation and simulation results show that beam emission from the cathode stick and the rod can be decreased evidently, furthermore the cathode stick can be removed. In addition, the magnetic distribution can ensure high efficiency and stability of multi-beam transport. At present, the multi-beam diode with combined magnetic system is being  experimented.

In this paper, a novel hybrid modeling method is proposed for radio wave propagation prediction. This method is based on parabolic equation in cylindrical coordinates and method of moments. The method of moments is used to model the radio wave propagation in the small cylindrical region containing the radiation source and the near source obstacle, and the parabolic equation in cylindrical coordinate system is used to model the radio wave propagation in a large region outside method of moments region. The transition surface between method of momenst and parabolic equation is carefully treated to avoid the incompleteness of numerical calculation. The hybrid algorithm proposed in this paper is suitable for predicting the radio wave propagation under various conditions, and it is applied for three different scenarios: the near source region contains a finite windowed obstacle, a finite cube obstacle and a semi-closed cube space obstacle. The calculation results of the hybrid algorithm are compared to those obtained from full method of moment implementations of the same scenarios to verify its accuracy.

To study the effect regularities of radar equipment under in-band continuous wave radiation and reveal the interference mechanism of in-band continuous wave on radar, a certain step-frequency radar was used as the test object to establish a test platform. We use the full-level irradiation method to carry out experimental research on the interference effect of radar. The in-band single-frequency electromagnetic radiation effect test results show that the radar under test has the effects of inaccurate ranging and suppressed target echo level due to the continuous wave radiation energy in the band. The ranging error radiated interference power varies irregularly, and the target echo level gradually decreases with the increase of the radiated power. The in-band single-frequency continuous wave radiation sensitivity test results show that the radar under test is very sensitive to the in-band electromagnetic radiation energy, and the minimum required radiation field strength of 0.32 V / m (at a frequency difference of −0.1 GHz) is enough for causing effective interference to the equipment under test (EUT). After the radiation frequency difference exceeds ± 0.16 GHz, the critical interference field strength starts to increase sharply. The continuous wave electromagnetic radiation effect of the radar under test shows obvious frequency selection characteristics.

To meet the urgent need of high-speed and high-quality wireless communication in tunnel environment, the high gain antenna suitable for tunnel environment is studied. A novel approach to improve the transmission quality of signals in tunnel by using two-element phased array antenna system is presented. The phased array antenna system consists of two high gain antennas and a phase shifter. By adjusting the phase of one antenna, the minimum amplitude of the superimposed electric field strength in the tunnel can be maximized, and the average electric field strength of the signals can be increased. The simulation results show that, compared with the signals transmitted by  single antenna, the minimum amplitude of the superimposed electric field strength of the  signals transmitted by phased array antenna system increases by 19.6 dB at least in the axial propagation range of 3 000 m tunnel, and at least a 12.4 dB augmentation of the minimum electric field strength compared with the signals transmitted by  two antennas simultaneously; the system achieves better diversity optimization effect, eliminates the deep fading caused by multipath effect, and solves the communication problem in tunnel environment.

High-density, high-resolution, and high-speed X-ray digital imaging detection requires a high-energy microfocus and high-dose X-ray source. A high quality electron beam source is the key means to achieve this X-ray source. Based on the main accelerator of the terahertz free electron laser of the China Academy of Engineering Physics (CTFEL), a high-energy microfocus X-ray source achieved by the high-brightness electron beam with low emittance and low energy spread was verified. The 9 MeV electron beam with full width at half-maximum of less than 70 μm was obtained. An initial imaging experiment was also carried out. The focal spot of the dual-wire image quality meter clearly distinguished the 9D wire with a wire diameter of 0.13 mm.

Focal spot size is a key parameter for evaluating the resolving power of the accelerator. A reduction in the focal spot size can effectively improve the spatial resolution of the object. This work studies and designs collimator structures for spatial restriction, which help to reduce the geometry blur of imaging and thus obtain a smaller effective spot-size. The Monte Carlo method is applied to simulate the generation of the light source and the imaging process of the spatial restriction structures. The parameters of the light source with different collimator structures are analyzed, including the distribution and size of the effective focal spot, the angular distribution and the spectrum of the photons. Theoretical calculations show that an effective focal spot size with a sub-mm scale can be obtained by means of spatial restriction at the expense of a partial loss of the field-of-view and the exposure.

It is can be bring optical-transition radiation(OTR) when the charged partical constant speed passed through interface of two dissimilarity intermedium. The radiation showed polarization behavior while the charged partical arrive at incidence plane, it is can be confirm energy of incidence partical corresponding OTR angle distribution patterns. The OTR angle distribution had polarization behavior at secondarily foil’s surface due to interference happened while electron beam entered the double foil system. It is can be measure parameter of pulse electron beam by used these phenomenon, The parameter includes electron beam envelope radius, landscape orientation distribution of electron beam current density, and electron beam energy, electron beam landscape orientation divergence angle distribution. using this theory to measure parameter of pulse electron beam basing on a series of Dragon LIAs and obtains valid time-resolved results. This measurement ability has improved greatly the debugging efficiency of a series of Dragon LIAs.

A novel adjustable aperture is developed for the low energy beam transport line (LEBT) of the China Accelerator Driven Subcritical System (C-ADS). Two relatively rotating mirror-symmetry cores are adopted for the adjustable aperture to scrape unwanted outer particles, improve the beam quality and reduce the beam losses, and most of all, realize continuously tunable beam current and meet the requirement of round beam. The results of simulation and test show that the unwanted outer particles can be cut away and the beam current can be adjusted continuously online within the range of 0 to 10 mA. This device provides a convenient beam tuning method for the proton linear accelerator, which can satisfy the stable and reliable online operation of C-ADS linear accelerator.

Pulsed power technology has been widely used in industrial and biomedical applications. In many cases, high-voltage pulses with current amplitudes up to hundreds of amperes are required. Although solid-state Marx generators have been studied for a couple of years, the rated current of power semiconductor switches such as IGBT and MOSFET in Direct Insertion Packaging (DIP) is usually much lower than 100 A, which cannot meet the high-current requirements for low-impedance load. Therefore, two topologies of the multiple Marx generators in parallel are proposed to increase the amplitudes of output current. In the first structure, multiple Marx generators are connected in parallel directly. In the second structure, multiple Marx generators sharing a series of charging switches are connected in parallel. An FPGA provides two control signals for charging and discharging. Using many transformers with their primary winding in series, synchronous driving signals with negative bias voltage are realized. And the main circuit adopts the solid-state rectangular Marx circuit based on half-bridge units. Power IGBTs which has fast opening speed and high current capacity are utilized as the main switches. The experimental results show that the pulse generator with six 16-stage Marx generators directly connected in parallel can output high-voltage rectangular pulses with voltage amplitude up to 10 kV and peak current up to 300 A through a 30 Ω resistive load at a repetition frequency of 100 Hz. The peak output current of six 4-stage Marx generators in parallel with shared charging switches can reach 300 A with a rising time of 230 ns, and the maximum output current can reach 460 A with a rising time of 272 ns through a 5 Ω resistive load. The results show that the parallel connection of multiple Marx generators can effectively reduce the internal resistance of the system and improve the current capacity of the system. Moreover, multiple Marx generators in parallel with shared charging switches not only output high-current pulses, but also halve the number of switches while the EMC is also improved. The current balancing can be further improved by inserting the parallel connection between stages.

A parallel finite difference time domain (FDTD) method combined with perfectly magnetic conductor (PMC) image method and CST software is firstly presented for computing the leakage field ( including sideward and backward leakage field)  from vertically polarized bounded wave electromagnetic pulse (EMP) simulator with distributed load. The results got from simulation agree well with those from experiment. Numerical results show that the leakage field’s peak-value near the ground reaches maximum in the direction of height, but there’s little difference of leakage fields’ peak-values at the testing points under 1.5 m height and far away from the simulator; The peak-values of sideward leakage field from simulator’s transitional section are larger than those from distributed load section, both of them are larger than the backward leakage field from the end of distributed load section, as the testing point is near the simulator, and the backward leakage field may be larger than those sideward leakage fields, as the vertically distance between the testing point and the simulator increases; The regularity conclusion suits for the simulator with different double exponential source. The more excited source component in high frequency domain, the larger backward leakage field in some distance domain. The leakage field from the simulator increases, as ground’s conductivity increases.

The armature-rail contact interface affects the characteristics of armature startup in the pulsed high current linear driver. Furthermore, the armature startup has an influence on the system efficiency and lifetime. This paper discusses the effect of armature surface morphology on armature startup. In the experiments, a high-speed camera was set up to observe the armature startup. Combined with the finite element software ANSYS, the pre-tightening force and contact status were simulated. Besides, the electromagnetic pressure and current density were also obtained by simulation. The results show that groove increased the flexibility of armature and the homogeneity of current distribution was improved by the current skin effect. Owing to the increasing pressure, the groove armature startup was delayed and its contact resistance reduced. The results have important significance to improve contact condition and reduce erosion.

This paper presents the study on the ²⁴¹Am-Be radionuclide sources reference neutron radiation field metrology characteristics for calibrating area neutron dose monitoring instruments. The Monte Carlo method was used to simulate the neutron ambient dose equivalent rate, scattering neutron proportion and neutron energy spectrum distribution at different points of test in the air free-field reference neutron radiation (FRNR), the minimum size of standard reference neutron radiation (SRNR) specified in GB/T 14055 series standards and the actual reference neutron radiation (ARNR). The results show that air has little effect on the dose rate and energy spectrum distribution in FRNR, which is approximately an ideal reference neutron radiation; the minimum size SRNR shielded by polyethylene containing 5% boron can decrease thermal neutrons and reduce the proportion of scattered neutrons. The shadow-cone method is not suitable for the correction of scattered neutrons in small-sized reference neutron radiation; scattering neutrons in ARNR are fewer and have a lower proportion, and the proportion of scattered neutrons obtained by shadow-cone method is basically consistent with the theoretical values.

The distribution characteristics of hydrogen flow in local single space is a special concern of nuclear power plant and hydrogen storage device. In this paper, a single compartment of the experimental device is used as a geometric structure to establish a computational fluid dynamics analysis model for the numerical study of hydrogen distribution in small-scale space. By comparing the experimental data with the simulated data, the choice of the optimal turbulence model is given, and the flow distribution of hydrogen in small-scale space under low mass flow rate condition is simulated. The numerical simulation results obtained by Realizable k-ε, RNG k-ε and Standard k-ε turbulence models in the six two-equation turbulence models agree well with the experimental data, which can accurately reflect the release process and distribution of hydrogen in small-scale space. In low mass flow rate case, the radial range of the mainstream region of hydrogen is small, and hydrogen is stably and evenly distributed in the middle and upper part of the compartment.

Disinfection and sterilization technologies are of great significance in the food industry, medical field and water treatment, et al. Compared with traditional chemical and thermal methods, physical disinfection and sterilization approaches such as γ-rays, X-rays, electron beams, microwaves, low-temperature plasmas, ultraviolet rays and high-voltage pulsed electric fields have the advantages of no environmental pollution, low sterilization temperatures, no chemical residues, and so on. These physical disinfection and sterilization approaches are getting increasing concerns because of unique advantages. In this paper, the mechanisms of present physical disinfection and sterilization technics were summarized. The advantages and disadvantages of these physical means as well as their application areas are reviewed. Based on the superiorities and drawbacks of each method, different approaches should be adopted for the disinfection and sterilization of specific objects. Moreover, this paper highlights the trends on development of physical disinfection and sterilization approaches and proposes the extensive demands of the physical approaches on various aspects of our life.