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:
Three-dimensional cylindrical coordinate conformal grid generated technology for particle-in-cell of high-power microwave device
Zhang Lei, Weng Ming, Wang Yue, Jiang Ming
 doi: 10.11884/HPLPB202335.230299
[Abstract](4) [PDF 2883KB](0)
Based on the object-oriented C++ language, a 3D cylindrical coordinate conformal grid generation program is developed. The conformal grid generation of beam-field interaction(BFI) device discretizing is performed, providing integral line and face elements for Particle-in-Cell simulation algorithm. By defining the basic elements of the three-dimensional cylindrical coordinate grid system, including grid step- size, grid index, guardian grid layer and bounding box, the spatial information of the model can be converted into the information of the cylindrical coordinate grid information necessary for numerical calculation. The grid cells on-axis should be specially treated so as to maintain the consistency of the particle-in-cell algorithm between the axial grid and the non-axial grid. The discrete boundary points on the model subsurface and on the model edge were attained by ray-tracing algorithm. Meanwhile, the vertices of the model were obtained by topological relations. Recording topological information and cylindrical coordinate grid information of the two types of boundary points and model vertices, then the basic grid elements were coupled with the boundary point information, finally the model was reconstructed in the discrete grid system. Taking the relativistic magnetron for example, using the conformal grid generation technique proposed in the paper to discretize the model, the transparent cathode, anode, and resonant cavity structures of the magnetron can be identified.
Development of primary magnetic field coil power supply system of kilo-tesla cylindrical implosion magnetic flux compression generator
Zhao Juan, Cheng Chen, Li Bo, Wu Gang, Kuang Xuewu, Xu Chao, Zhou Zhongyu, Zhang Xuping, Tang Xiaosong, Li Jianmin, Tong Yanjin, Gu Zhuowei
 doi: 10.11884/HPLPB202335.230194
[Abstract](5) [PDF 3783KB](0)
The primary magnetic field coil (PMFC) power supply system is designed for pumping the PMFC of the kilo-Tesla cylindrical implosion magnetic flux compression generator (MC-1) to produce initial magnetic field. It is the key equipment of the MC-1 system. Based on analysis of the requirements and the key techniques, the design of the key components, pulsed forming circuits and control system of the PMFC power supply system was presented. The power supply system with the output voltage is adjustable from 1 kV to 40 kV, the rise front is about 60 μs and the peak current reached 3.2 MA was developed successfully. The power supply system had been applied to the dynamic test of the kilo-Tesla cylindrical implosion magnetic flux compression (MC-1) generator.
Technology and applications of T/R dual-mode microwave power module
Li Jianbing, Qiu Li, Wang Bin, GuoJingkun, Dong Xueyu
 doi: 10.11884/HPLPB202335.230184
[Abstract](19) [PDF 4145KB](4)
Microwave power module (MPM) is a new type of microwave power device which is a combination of vacuum electronic devices and solid-state electronic devices. It has the characteristics of high frequency, wide bandwidth, large power and small volume and weight, which makes the application of conventional traveling wave tubes more convenient and extensive. Modern warfare is developing towards the integration of radar and electronic warfare, which requires that the power amplifier can work in both high-mode with high peak power and low duty cycle and low-mode with low peak power and quasi-continuous wave. In order to meet this demand, combined with the requirements of common aperture of electronic system, T/R dual-mode MPM technology is proposed. The core of T/R dual-mode MPM technology is T/R dual-mode traveling wave tube. Based on three-port bidirectional T/R traveling wave tube, the signal reverse receiving function of traveling wave tube is realized by setting a coupling port near the attenuator of slow wave system. The dual-mode bidirectional function of MPM is realized through the design of T/R dual-mode traveling wave tube, dual-mode amplifier and equalizer, and dual-modulation grid power supply. T/R dual-mode MPM has broad application prospects, especially in combat applications based on Unmanned Aerial Vehicle platform.
A design and simulation for fast corrector magnet power supply
Wang Dongxing, Huang Maomao, Wu Wanfeng
 doi: 10.11884/HPLPB202335.230239
[Abstract](28) [PDF 1741KB](9)
The power supply for fast corrector is an important type of equipment in light sources and accelerators. With the improvement of the performance of the light source, the accelerator has put forward higher requirements for the performance of the fast corrector and their corresponding power supply. In order to meet the requirements of the power supply for fast corrector and simplify their design process, the research of control strategy and simulation about power supply for the fast corrector are developed. This paper proposed a way which use the PI control plus second-order phase compensation as the control strategy of the power supply for fast corrector. For improving the phase margin of the power supply system, the bode diagram is used to design the phase compensation parameters of the power supply fast corrector. This method not only ensures that the power supply system works in the deep negative feedback state, but also simplifies the process of parameter calculation about phase compensation. For the sake of verifying the correctness and effectiveness of the control strategy, this paper proposes a simulation method based on the transfer function of switching power supply which uses voltage controlled voltage source instead of switching devices. The simulation results verify the feasibility and effectiveness of the above control strategies, and verify the effectiveness and efficiency of the above simulation methods.
Study on law of two-dimensional plate relativistic electron beam to target
Gao Lei, Hao Jianhong, Zhang Fang, Zhao Qiang, Fan Jieqing, Xue Bixi, Dong Zhiwe
 doi: 10.11884/HPLPB202335.230101
[Abstract](22) [PDF 2004KB](2)
The relativistic electron beam can hit the target with a high injection rate under the ideal paramagnetic environment, but in reality, due to the influence of the environment, the transmission direction of the relativistic electron beam may deviate from the geomagnetic field at a small angle, and thus the Larmor inlet will be generated by the action of the geomagnetic field, which affects the target aiming of the electron beam as well as the amount of the injection to the target. In this paper, based on the two-dimensional sheet relativistic electron beam, respectively on the relativistic electron beam paramagnetic and deviation from the magnetic field 3 ° angle two kinds of transmission simulation, through the simulation of the transmission process of the beam group, analyze and study the paramagnetic environment of different transmission distance group to the target rate of the change rule, as well as deviation from the magnetic field of the change rule of the rate of the amount of injection of the transmission process 3 ° angle, for the relativistic electron beam to the target rate of the estimation and target targeting This will provide data reference for the prediction of relativistic electron beam-to-target rate and target aiming.
Design and analysis of kA stepped pulse current generation scheme
Chen Junhong, Xiao Donghua, Xiong Yuzhen, Wang Yingqiao, Chen Xiaochang, Xuan Weimin, Ji Yang
 doi: 10.11884/HPLPB202335.230243
[Abstract](14) [PDF 2601KB](1)
Toroidal magnetic field should match frequency of the electron cyclotron wave in pre-ionization process of the Tokamak device. Existing electron cyclotron wave frequency of the NCST (Nan Chang Spherical Tokamak) is low. New toroidal coil current generation scheme is proposed to match current electron cyclotron wave frequency. A low current step is added before existing flat top current of original scheme. After reviewing original scheme of toroidal coil power supply of NCST, two schemes of full control and semi-control are designed. Advantages and disadvantages of the two schemes are compared from four aspects: high order harmonics of voltage and current, controllability and ripple of current, modification cost and installation convenience, and finally semi-control transformation scheme is selected. Power supply modification cabinet is made according to field conditions to minimize alteration of original power supply cabinet. Actual test results show that two current steps are connected normally, and width and amplitude of low current steps are adjustable, which meets transformation requirements.
Critical field strength estimation for microwave pulse atmospheric breakdown
Yang Hao, Huang Nuoci, Liu Xingchen, Zheng Qianglin, Bao Xiangyang, Yan Eryan
 doi: 10.11884/HPLPB202335.230248
[Abstract](23) [PDF 645KB](3)
In response to the possible breakdown phenomenon of high-power microwave in atmospheric transmission, the article focuses on studying the first breakdown delay pulse number in pulse sequences. It is found that it is closely related to seed electrons, pulse breakdown probability, and microwave field strength. Microwave field strength can indirectly affect the pulse breakdown probability and delay pulse number through seed electrons. A method is proposed to estimate the critical field strength of microwave breakdown using the number of delayed pulses, and the microwave critical field strength is defined as the breakdown threshold when the probability of pulse breakdown is greater than a certain value. In this paper, the estimation formula of pulse impulse breakdown probability is derived, and the performance of the Estimator is analyzed. Then, the experimental verification is carried out using the S band microwave atmospheric breakdown simulation device. The experimental results show that, within a certain range, the number of pulse delays for repetitive frequency microwave pulse breakdown is only inversely proportional to the seed electron generation rate and pulse width, and can be used to estimate the probability of pulse breakdown, thereby giving the critical field strength for breakdown.
Parameter optimization design of snubber circuit for high voltage protection switch
Li Zhiheng, Ma Shaoxiang, Zhang Hongqi, Zhu Bangyou, Zhang Ming, Yu Kexun, Pan Yuan
 doi: 10.11884/HPLPB202335.230158
[Abstract](24) [PDF 3158KB](11)
The ion source and electron gyrotron of the fusion auxiliary heating system are prone to failure and expensive. In order to protect them, it is necessary to study the high voltage switch scheme. The parameter design methods of high voltage protection switch snubber circuit are lack of relevant theoretical design methods currently, and the snubber circuit schemes are isoparametric design schemes because the influence of distributed capacitance is not taken into account in the design process. The voltage-balancing effect of this method is not ideal. In order to solve the problems existing in the current parameter design, we establish the MOSFET model with snubber circuit and stray inductor firstly and analyze its turn-off process, thus the theoretical design method and expression of snubber circuit for suppressing voltage spike are obtained. In order to solve the problem that the distributed capacitance is not considered in series voltage-balancing, by constructing the isoelectric point, we establish and analyze the equivalent circuit with distributed capacitance, and obtain the non-equal parameter design method and expression of snubber circuit according to the charge equation. This parameter design method can compensate the uneven voltage distribution caused by distributed capacitance and guide the voltage-balancing scheme design of high voltage protection switch better. In order to verify the rationality of the parameter design, the simulation analysis is carried out. The simulation results show that the overall design scheme can meet the design requirements of peak suppression and voltage-balancing.
Numerical study on high frequency characteristics of slow plasma wave in cylindrical waveguide loaded with annular plasma beam
Yang Wenyuan, Dong Zhiwei, Dong Ye, Zhou Qianhong
 doi: 10.11884/HPLPB202436.230275
[Abstract](23) [PDF 5281KB](0)
As a kind of high power microwave generator, the plasma relativistic microwave generators (PRMGs) have the virtues of wideband high power microwave output and fine frequency tunability. Thus the PRMG is very useful for a wide variety of applications. The beam-wave interaction region in the PRMG is generally a cylindrical metal waveguide with preformed annular plasma. The dispersion characteristics of the operating slow plasma wave TM01 mode(called as P-TM01 mode below) in the interaction region are critical to the output properties. Therefore, the dispersion characteristics and field distributions of the P-TM01 mode in a cylindrical waveguide loaded with annular plasma beam is studied numerically using the all electromagnetic PIC(Particle-in-Cell) code. Variation trends of the dispersion characteristics and the field distributions of the P-TM01 mode with the density np, radial thickness Δrp and radial position rp of the plasma beam, the intensity of the guiding magnetic field Bz and the radius of the waveguide rw are obtained. Simulation results show that: (1) Both np and Δrp affect the dispersion characteristics markedly and the frequency of the P-TM01 mode increases with the increasing of either np or Δrp at the same axial wave number kz. (2)Variations of rp, rw or Bz have very slight influence on the dispersion in the interested range. It is indicated that one can choose relatively larger dimensions of the waveguide for larger power capacity and lower guiding magnetic field for compactness if necessary. (3) The basic features of the field distributions of the P-TM01 mode will not be changed with the variations of the above mentioned physical parameters. But with the increasing of axial mode number and kz, the electromagnetic energy will be trapped inside the plasma beam gradually and no effective beam-wave interaction will happen in the end. Therefore, it is suggested to choose the operating point with relatively small kz for the efficient operation of PRMG.
High speed package on package structure designed for SiC-MOSFET and its performance evaluation
Ma Jiuxin, Ma Jianhao, Ren Lüheng, Yu Liang, Yao Chenguo, Dong Shoulong
 doi: 10.11884/HPLPB202335.230212
[Abstract](35) [PDF 13259KB](3)
As the core component of pulse power system, switch plays an important role in pulse forming and power modulation. Usually, the rise time of the pulse generated is often determined by the on-off speed and the high-speed switch is vital to the formation of nanosecond short pulses.Therefore, this paper proposed a high-speed SiC-MOSFET package on package structure. The overall layout has no lead or external connection, and has very low parasitic inductance. In this paper, the electromagnetic field simulation research of the proposed package is carried out, and the electromagnetic field distribution of the multi-media interface of the package is revealed during the pulse formation process.The electromagnetic weak link of the package structure is clarified, which provides guidance for further insulation optimization. A dual-pulse test platform was built to compare the dynamic performance of the proposed package on package structure switch and the commercial TO-263-7 package switch. The experimental results show that under high current conditions, the proposed packaging improves the turnning off by 48%, the turnning off speed by 50%, the turnning on loss by 54.6%, and the turnning off loss by 62.8%. The experimental results verify the improvement effect of package on package structure on the dynamic performance of the switch.
Primary study on time control technology of active phasedarray based on photoconductive microwave source
NiuXinyue, GuYanran, ChuXu, Yao Jinmei, YiMuyu, Wang Langning, Xun Tao
 doi: 10.11884/HPLPB202335.230260
[Abstract](26) [PDF 681KB](2)
Solid-state photoconductive microwave source based on wide-bandgap photoconductive semiconductor is a new way of high power microwave generation. The scheme has the characteristics of high power density and wide frequency band, and its low time jitter characteristics make it have great potential in power synthesis. The construction of active phased array of photoconductive microwave devices using optical beamforming network is an important way for the application of photoconductive microwave devices. In this paper, the principle of optical microwave phased array system is analyzed, and the theoretical models of differential true delay phased array and true delay phased array considering phase random error are constructed. The key factors affecting power synthesis and beam scanning are quantitatively analyzed and simulated, and the delay precision index is proposed.The results show that for the n×10 array transmitting signal at 1 GHz, when the delay phase variance is less than 10 ps, the pointing deviation is less than 0.2°and the peak gain loss is less than 2%. When the delay step accuracy is less than 10 ps, the pointing deviation is less than 0.2°, and the peak gain loss is less than 0.03%. On this basis, the real time delay network architecture of photoconductive microwave is designed, which provides a reference for the development of higher power and larger scale photoconductive microwave synthesis technology in the future.
Radar radiation source recognition method based on compressed residual network
Guo Enze, LiuZhengtang, CuiBo, LiuGuobin, ShiHangyu, Jiang Xu
 doi: 10.11884/HPLPB202335.230119
[Abstract](28) [PDF 1931KB](1)
Aiming at the problems of low recognition accuracy and poor timeliness of existing radar emitter signal recognition methods under the condition of low SNR, this paper proposes a radar emitter signal recognition method based on compressed residual network. Using Choi-Williams distribution for reference, the time-domain signal is converted into a two-dimensional time-frequency image, which improves the effectiveness of signal essential feature extraction. According to the characteristics of the application scenario, select the “compression” range of convolutional neural networks (CNN), and build a compression residual network to automatically extract image features and identify. The simulation results show that compared with other advanced models, the proposed method can reduce the running time of signal recognition by about 8.4 times, and the average recognition rate of 14 radar emitter signals is at least 5% higher when the signal-to-noise ratio is −14 dB. This paper provides an efficient intelligent recognition method of radar emitter signal, which has potential engineering application prospects.
Simulation and verification of 3D temperature model for high power microwave heating
Wu Hao, Li Shaofu, Wang Wei, Jiang Cheng, Tang Yingying
 doi: 10.11884/HPLPB202335.230281
[Abstract](37) [FullText HTML](10) [PDF 11662KB](3)
Microwave heating inhomogeneity has always been a hot issue in the minds of researchers engaged in microwave heating control. According to the physical structure of the microwave heating device, the static difference model of the surface temperature of each layer in the furnace is established, and the actual power of microwave heating is obtained by combining with experiments. Based on the finite difference method of heat transfer, the temperature distribution model in 3D space is established, and the effectiveness of the model is verified by MATLAB and COMSOL simulation. Compare the equilibrium temperature of the heated medium obtained by uniformly heating the microwave with the temperature distribution during uneven heating, and identify the partial temperature rise equilibrium point of the medium during the microwave heating process. Finally, it is compared with each other to find out the best point for the control object for expert PID (proportion-integral-derivative) microwave heating. The experimental results show that this method can accurately measure the equilibrium temperature of liquid heated medium at any time, and can make microwave heating more widely used in industrial production.
Load mismatch effects to HBT device based on waveform measurement
Zhang Jinhao, Su Jiangtao, Xie Weiyu, Shao Shiyuan, Xu Kuiwen, Li Wenjun
 doi: 10.11884/HPLPB202335.230214
[Abstract](51) [PDF 6062KB](0)
Under the impact of high-power electromagnetic pulses, RF integrated microsystems are prone to generate load mismatch, which may lead to system failure or even damage. Based on a real-time waveform test method, this paper analyzes the mechanism of load mismatch of RF devices leading to device damage. This method utilizes vector network analyzer as the main instrument, obtaining the real-time voltage and current waveforms with reflection signal and phase reference module. Active load-pull technique is used to simulate high power coupled electromagnetic pulse injection and ruggedness test under 39∶1 VSWR is done. Furthermore, newly applied harmonic source injection to simulate the electromagnetic interference caused by harmonics, obtaining the harmonic impedance mismatch characteristics of the device. The test results of actual heterojunction bipolar transistor device indicate that the combination of fundamental and harmonic interference components causes the transient peak value of the output voltage to be higher, which is more likely to damage the device. Hence the fundamental and harmonic components should be considered when conducting electromagnetic protection.
Design and implementation of a miniaturized high voltage power supply for pulse traveling wave tube
Liu Yinchuan, Gao Wenlei, Wang Yafeng, Liu Qihui, Chen Yinxing
 doi: 10.11884/HPLPB202335.230207
[Abstract](49) [PDF 2815KB](9)
In order to meet the demand of radar for miniaturization of transmitter, a miniaturized high-voltage power supply is designed for a certain type of TWT. The high voltage power supply adopts a phase shifted full bridge topology structure, and the high voltage rectifier circuit uses SiC diodes to improve the power density of the power supply. A miniaturized pulse high-voltage power supply has been developed, with a cathode voltage of −6.5 kV, a maximum working pulse width of 2 ms, and a peak power of 1600 W. The joint test with Traveling-wave tube shows that the output RF power of TWT is stable during pulse operation. The test results verify the feasibility of the design method.
Discharge characteristics on DBD of the three electrode structure under dual-source excitation
Jiang Song, Zhang Zhengdong, WANG Yonggang, LI Zi, Zhonghang Wu
 doi: 10.11884/HPLPB202335.230173
[Abstract](88) [PDF 2083KB](4)
Dielectric barrier discharge (DBD) is widely used in industry, but the efficiency limits its further application. In this paper, a three-electrode structure combining a DBD structure and a needle-plate structure is proposed. A positive polarity pulsed power supply is applied to the DBD electrode and a negative polarity pulsed power supply is applied to the needle plate electrode. The discharge characteristics, phenomena and spectral intensity of the three-electrode DBD under different structures were analyzed. The results show that the three-electrode structure is more beneficial to the generation of DBD discharge channels, and its discharge uniformity and luminous intensity are stronger than that of the two-electrode DBD, especially under the condition of mesh grounded electrode. When the positive polarity voltage of the three-electrode structure was maintained at 11 kV and the negative polarity voltage was -5 kV, the peak discharge current of DBD in the mesh grounded three-electrode reached 1.54 A, while the peak discharge currents of DBD in the solid grounded three-electrode and the traditional two-electrode were 1.14 A and 0.74 A. During the period of the negative polarity pulse maintenance, the needle mesh gap was in the state of breakdown, and the DBD discharges appeared to have a large discharge current. In the three-electrode structure, the three-electrode DBD discharges also become more intense with the increase of the negative polarity voltage applied to the needle plate. According to the discharge spectra of DBD under different structures, spectral intensity of excited particles is the strongest among the three electrodes DBD grounded with wire mesh. This trend is consistent with the discharge current and power of DBD.
Investigation of a compact solid-state Marx generator
Yao Haowei, Li Zi, Wang Yonggang, Jiang Song, Rao Junfeng
 doi: 10.11884/HPLPB202335.230148
[Abstract](151) [PDF 5844KB](24)
With the rapid advances in pulsed power technology, high-voltage pulse power supply is gradually developing towards modularization and miniaturization while ensuring high-voltage output. All-solid-state Marx generators generate pulses with flexible parameters adjustment and are increasingly used in a wide range of applications. Synchronous isolated driving is the core technology of solid-state Marx generators. In this paper, a compact solid-state Marx generator based on half-bridge structure was proposed. In each stage, a NPN MOSFET as the charging switch and a PNP MOSFET as the discharging switch forms a half-bridge circuit, and both their gates and sources were short circuited so they can be triggered with the same signal. Using many transformers with their primary windings in series, only one half-bridge circuit on the primary side was used to transfer both the driving power and control signals. Then all the charging switches and discharging switches were driven simultaneously, which greatly simplifies the structure and size of solid-state Marx generators and reduced costs. In this way, a 24-stage solid-state Marx generator prototype was built, and high-voltage square pulses of 10 kV, 1 kHz and 5 μs was obtained on a 10 kΩ resistive load. The feasibility of the scheme is verified, and the length, width and height of the main circuit is only 20 cm×13 cm×5.5 cm.
Study of the influence of uniform orthogonal background magnetic field on the equivalent inductance of toroidal magnetic cores based on magnetic equivalent circuit network method
Wang Shaoyu, Yang Yong, Zhang Ming
 doi: 10.11884/HPLPB202335.230155
[Abstract](99) [PDF 14088KB](15)
The magnetic components in power supplies are naturally sensitive to external magnetic fields, and their operating characteristics directly affect the output characteristics of the power supply. Modeling the background magnetic field is an important prerequisite for the study of the interference of magnetic components in power supplies by strong stray magnetic fields, but few studies have focused on this application scenario, and the commonly used methods for electromagnetic field analysis are difficult to balance accuracy and efficiency. In this paper, we propose a method to analyze the effects of stray magnetic fields based on the equivalent magnetic circuit network method, which discrete the research object into magnetic circuit units, equivalently form a network model, and obtain the field distribution of the model by solving the equations of the equivalent magnetic circuit system. We take a toroidal ferrite core as an example, and use the equivalent circuit network method to calculate the field distribution of the toroidal core under DC excitation and uniform orthogonal magnetic field, and analyze the effect of the background magnetic field on its equivalent inductance. By comparing the results of the equivalent circuit network method with those of the finite element method, the accuracy and efficiency of the proposed analysis method are demonstrated, and it is shown that the method is applicable to the analysis of power supplies disturbed by the background magnetic field.
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:
Research on solid state Marx power supply with fast frontiers
Li Dongsheng, Li Zi, Wang Yonggang, Jiang Song, Rao Junfeng
 doi: 10.11884/HPLPB202436.230197
[Abstract](25) [PDF 2985KB](4)
Nanosecond pulse electric field ablation requires the generation of thousands of volts of nanosecond pulses on a 100 Ω load, and accelerating the pulse front is beneficial for obtaining narrower nanosecond pulses. This article proposes a solid-state Marx generator with a fast front, which inserts an inductor into each stage of the circuit and allows the discharge tube and charging tube to conduct simultaneously for tens of nanoseconds. After the discharge tube is fully opened, the charging tube is turned off to discharge the load, eliminating the limitation of stray inductance on the pulse front by the discharge tube and discharge circuit, and obtaining a high-voltage pulse with a fast front. A 32 level Marx prototype was built, and in the experiment, a high-voltage pulse with a voltage rise of 35 ns, a pulse width of 800 ns, and a current of 186 A was obtained on a low resistance load of 100 Ω by adjusting the through time. We compared and analyzed the effect of the direct time between the charging tube and the discharge tube on the rising edge, and found that the longer the direct time, the faster the front of the pulse current. The maximum peak current at the output end can reach 186 A. This indicates that the pulse voltage source can effectively increase the current output and improve the system’s load capacity. Compared with traditional improvement methods, this scheme not only improves the system’s anti-interference ability, but also reduces the number of switches used and reduces the cost of pulse power supply.
Lightweight design of new all-solid-stage modular multilevel special high-voltage power supply
Li Yushan, Qian Weigang, Teng Jiaxun, Sun Xiaofeng
 doi: 10.11884/HPLPB202436.230322
[Abstract](44) [PDF 6577KB](4)
Modular multilevel converter (MMC) has become an effective solution for new all-solid-state special high-voltage power supply, and its lightweight design to save equipment space cost has become a research hotspot. The primary factor limiting power density in MMC is the large size capacitance of submodule (SM), and in order to reduce the demand for the capacitance of the sub-module in modular multilevel converter, and increase system power density, an improved MMC(I-MMC) topology is proposed. Using isolated switched capacitor converters, a pair of SMs of the upper and lower arms are interconnected through a high frequency link. In the research, synchronous control is adopted on both sides of the high-frequency chain connecting the upper and lower arms of the pair of SMs in the phase unit to make the SM capacitors present the characteristics of switched capacitors, realize the free transfer of fluctuating power between the capacitors, and eliminate the fundamental frequency and phase opposite 3 times frequency fluctuation component. Combining MMC operation modulation ratio and power factor, analyze the value of SM capacitor after the fundamental frequency and 3 times frequency fluctuation components are eliminated, and complete the modular design. This solution can reduce the sub-module capacitance to 1/4 of the conventional MMC. Simulation and experimental results verify the correctness and the validity of the proposed topology scheme.
Design of high-voltage components for acceleration grid power supply of neutral beam injection system
Zhang Hongqi, Li Zhiheng, Ma Shaoxiang, Zhang Ming
 doi: 10.11884/HPLPB202436.230159
[Abstract](45) [PDF 14841KB](7)
Negative-ion based neutral beam injection is an indispensable auxiliary heating method for future large tokamak devices. The acceleration grid power supply in the neutral beam system requires an output voltage of -200 kV and a power of 5 MW, and often faces special conditions of sudden short-circuit and disconnection of the load. The design of the high-voltage components is still missing in the research of the acceleration grid power supply. The insulation design of the high-voltage components is a critical part of the power supply development process. In this paper, the circuit parameters of the step-up transformer, high-voltage rectifier and high-voltage filter of the high-voltage part of the power supply are calculated according to the power supply index and the characteristics of the special working conditions, the engineering design based on oil-immersed insulation of these parts is also carried out, and the insulation is verified by finite element simulation analysis. The simulation results show that the maximum electric field strength in these components is 16.22 kV/mm, which is less than the transformer oil breakdown field strength and has 2 times the insulation margin. The structural design of the high-voltage components in this paper can meet the insulation requirements of the power supply.
Research on electromagnetic crosstalk in double differential mode unshielded cable loop
Peng Ning, Yang Yong, Zhang Ming, Rao Bo, Zhang Zhengqing
 doi: 10.11884/HPLPB202436.230228
[Abstract](68) [PDF 1580KB](7)
With the development of electrification, it has been paid more and more attention to the electromagnetic compatibility in electrical and electronic systems. To suppress the effects of electromagnetic interference and achieve electromagnetic compatible operation of equipment or components, it is necessary to research the crosstalk between cables. However, few researches have focused on the electromagnetic crosstalk between double differential mode loops consisting of a generator loop, a receptor loop, and the ground. In this paper, a five-conductor transmission line model based on the multi-conductor transmission line theory is proposed, and the crosstalk between double differential mode unshielded cable loops is researched based on it. According to the coupling mechanism, the method firstly establishes the equivalent model of unit-length five-conductor transmission line, then writes the system of Kirchhoff equations according to the method of finite difference, and finally solves the equations after supplementing the boundary conditions to obtain the crosstalk in the frequency domain. The crosstalk calculation results are compared with the simulation results of CST software to verify the feasibility and validity of the model and calculation method. The inductive coupling and capacitive coupling are studied respectively by the calculation, and the influence laws of different factors on the cable crosstalk are obtained by calculation and analysis, which can provide guidance for taking measures to suppress cable crosstalk in practical engineering.
Research on switching devices simplification of multistage XRAM pulse power supply
Zhang Yuchen, Dai Ling, Fan Shengting, Feng Yongjie, Lin Fuchang
 doi: 10.11884/HPLPB202436.230211
[Abstract](61) [PDF 1103KB](6)
The ability of electromagnetic emission mainly depends on the pulse power supply system, and the optimization of pulse power supply is one of the key technologies to make further breakthroughs in electromagnetic emission technology. Inductive energy storage type pulse power supply has great advantages in energy density and has far-reaching development potential. The XRAM pulse power supply based on series charging and parallel discharge has the advantages of simple structure and strong expandability. In this paper, the working principle of diode devices in multilevel XRAM power supply topology is analyzed, and a scheme is proposed to simplify the number of diode devices based on function classification. A simulation model is established for a 30-stage XRAM pulse power supply with a railgun load using ICCOS. Each power module consists of five stages, resulting in a total energy storage capacity of 365 kJ for the system, with an emission efficiency of nearly 20%. By comparing the simulation results of model performance indexes before and after simplification, it is proved that the simplified lower arm diode of the first stage is unfavorable to the operation of the multistage power supply. Simplifying the final countercurrent capacitor series diode in the multistage topology, and the antiparallel diode of charging thyristor under the premise of optimizing the countercurrent capacitor parameters, have no obvious effect on the discharge current of the power module.
Modeling and analysis of power processing unit based on secondary-side LLC resonant converter
Lu Honglin, Wu Xinjie, Zhang Debin, Qu Chengzhi, Zhang Zhongsong, Zhang Yu
 doi: 10.11884/HPLPB202436.230171
[Abstract](67) [PDF 2095KB](6)
With the continuous development of aerospace technology, the demand for Hall-electric propulsion power processing units (PPUs) in spacecraft is constantly increasing, and high-gain, high-power and high-efficiency PPUs have become the mainstream direction of research. The LLC topology enables soft switching over the full load range and therefore offers broad application prospects in PPU anode power supplies. Due to its primary and secondary gain characteristics, the primary LLC brings great challenges to the resonant inductance design of the high gain converter of the anode power supply. In view of the above problems, this paper proposes an improved secondary LLC resonant topology, which retains the soft switching characteristics of the primary LLC resonant circuit while effectively solving the resonant inductor design problem, so that the PPU anode power supply has high gain performance. In this paper, the mathematical model of the secondary LLC topology is first established by using the time domain analysis method, and then the calculation method of the peak gain is given on the basis of the model, and finally the correctness of the built model is verified by a prototype and the validity of the secondary LLC circuit is verified.
Leakage signal classification and recognition method based on fusion features
Kou Yunfeng, Dai Fei, Zhao Zhiguo, Lü Jianming, Ma Xie
 doi: 10.11884/HPLPB202335.230186
[Abstract](79) [PDF 8563KB](2)
With the development of networks such as mobile communications, Internet of Things (IoT), V2X ( meaning Vehicle to everything, including Vehicle to Vehicle and Vehicle to Infrastructure), and Industrial Internet of Things (IIoT), the electromagnetic environment is becoming increasingly complex, illegal electronic devices are also increasing day by day, and there are severe coupling and intermodulation of various signals, which bring difficulties to the identification of leaked signal types. This paper proposes a leakage signal classification and recognition method based on fused features. Comprehensively utilizing high-dimensional feature extraction methods and graphical dimensionality reduction characterization methods, and combining with deep learning models such as residual networks and feature fusion analysis methods, the method can distinguish more comprehensively multiple types of electromagnetic leakage signals. The features method has with high robustness against noise and good interpretability, and can support the intelligent detection engineering application of radiation sources based on electromagnetic signal type recognition.
A tightly coupled dipole array antenna with high power and broadband
Gong Hongzhou, Zhang Jiande, Yuan Chengwei, Zhang Qiang, Xu Liang
 doi: 10.11884/HPLPB202335.230139
[Abstract](247) [PDF 12009KB](33)
A novel tightly coupled dipole array antenna with high power and broadband is proposed in this paper. On the basis of conventional tightly coupled dipole array antennas, and by adopting an all-metal structure design, an integrated design of antenna matching layer and sealing layer, and a method of adjusting the antenna structure, a high-power and broadband performance of such an array antenna is obtained. The simulation results show that the standing wave ratio of the array antenna is less than 2 at the broadside in the range of 0.8-4.0 GHz. And the power capacity of an element antenna reaches 0.12 MW within the size of 16 mm × 32 mm in the space full of SF6 at one atmospheric pressure. Moreover, the power capacity of the 10×10 array antenna composed of 100 elements can reach 12 MW within the size of 320 mm × 640 mm in the space full of SF6 at one atmospheric pressure. In addition, the array antenna can achieve a wide-angle scan of 45°. The proposed array antenna provides a solution for high-power microwave broadband antennas to achieve a broadband, large-angle scanning, compact, miniaturized, and low-profile performance.
Cover and Contents
Cover and Contents, High Power Laser and Particle Beams, No 11, Vol 35, 2023
Editorial Office
[PDF 4712KB](43)
High Power Laser Physics and Technology
Recent progress of temporal coherent combination of chirped pulses in fiber lasers
Liu Bida, Huang Zhimeng, Zhang Fan, Xia Handing, Zhou Dandan, Li Jianbin, Zheng Junwen, Zhang Rui, Li Ping, Peng Zhitao, Zhu Qihua, Hu Dongxia
2023, 35: 111001.   doi: 10.11884/HPLPB202335.230308
[Abstract](186) [PDF 32091KB](79)

Temporal coherent combination further extends the pulse duration by assembling many pulses in a train passed through the amplifier into one output pulse, which can improve the peak power and pulse energy effectively and avoid nonlinear effects excited by the high peak power in the amplification. Spatial and temporal pulse combination can overcome limitations in single fiber laser, potentially leading to higher pulse energy, average power and peak power of ultrafast pulses currently only available from bulk amplifiers with low repetition rates. In this paper, the principles and key technologies of temporal coherent combination of ultrafast pulses in fiber lasers are introduced. The current status of temporal coherent combination and their technologies are reviewed. Recent progress of Divided Pulse Amplification (DPA) and Coherent Pulse Stacking (CPS) is emphasized. Different technical ways are compared and analyzed. Several future perspectives are pointed out. The paper can be a reference for research on temporal coherent combination of chirped pulses.

High power semiconductor lasers with output power over 16 W for single emitter and 180 W for bar operation at 780 nm under CW operation
Li Yi, Wang Haomiao, Zhang Liang, He Yuwen, Zhou Kun, Du Weichuan, He Linan, Hu Yao, Wu Deyong, Gao Songxin, Tang Chun
2023, 35: 111002.   doi: 10.11884/HPLPB202335.230073
[Abstract](161) [PDF 3823KB](63)
The single emitter and bars of 780 nm semiconductor laser have been designed and fabricated. The epitaxial layers were prepared by the metal organic chemical vapor deposition technology. GaAsP and GaInP were used as the quantum well and waveguide layer, respectively. The confinement layers were AlGaInP material with low refractive index. The bandgap between the quantum well and the waveguide layer was 0.15 eV, while the bandgap between the waveguide layer and the confinement layer was 0.28 eV. The high bandgap was effective in suppressing carrier leakage. The 1.55 μm thick large optical cavity epitaxy structure increases the beam’s size and alleviates the cavity optical surface damage problem. The asymmetric structure suppresses high-order fast axis modes. Using the ultra-high vacuum cleavage and passivation technology, an amorphous ZnSe passivation layer was deposited on the laser cavity facets. The ZnSe passivated single emitter device with 150 μm width and 4 mm cavity length, did not show COD phenomenon with 16.3 W continuous-wave output, when the current was 15 A. In this case, the slope efficiency reached 1.27 W/A while the electro-optic conversion efficiency was 58%, and the divergence angle of slow-axis was 9.9° and the spectral width was 1.81 nm. The 1-cm laser bar with lateral emitter fill factor of 40%, reached continuous-wave 180 W output power at 192 A, and the electro-optic conversion efficiency was 50.7%, the spectral width was 2.2 nm.
Design and analysis of the liquid crystal depolarizer based on random phase distribution
Zhang Yuqi, Wang Yuqin, Chen Dan, Zhang Rongzhu
2023, 35: 111003.   doi: 10.11884/HPLPB202335.230180
[Abstract](76) [PDF 8138KB](32)
To control the depolarization of incident laser with different polarization states, a liquid crystal depolarizer with random phase distribution structure is designed. For cholesteric liquid crystal device, a model of laser transmission through cholesteric liquid crystal device is established by using finite-difference time-domain method. The theoretical model is verified by experiments, and the polarization change and polarization distribution characteristics of laser through the liquid crystal array unit are analyzed. The simulation results show that the cholesteric liquid crystal device can achieve good depolarization effect for the linear polarized light with different polarization angles under the conditions of suitable liquid crystal material and maximum thickness of the micro-etching pit, and the applicable spectrum is wide.
Matrix effect based on laser-induced breakdown spectroscopy
Yao Yinxu, Qiu Rong, Wan Qing, Yang Yi, Shi Jinfang, Wang Huili, Zhou Qiang
2023, 35: 111004.   doi: 10.11884/HPLPB202335.230126
[Abstract](118) [PDF 1538KB](29)
To analyze and improve the matrix effect on the quantitative analysis of cadmium (Cd) concentration in soil and rice using laser induced breakdown spectroscopy (LIBS), this article takes the Cd Ⅱ 226.502 nm spectral line as the analysis object, and compares the effects of matrix type, KCl mass concentration, and excitation method on the intensity and quantitative analysis results of Cd Ⅱ 226.502 nm spectral line. The results show that the chemical form of the main components of the matrix and the ionization energy are the main factors that produce the matrix effect. KCl as an additive can significantly improve the spectral line intensity of Cd Ⅱ 226.502 nm in rice. The photoelectric double pulse excitation can significantly enhance the spectral line intensity and stability of Cd Ⅱ 226.502 nm in the matrix, and improve the signal to noise ratio. Compared with the single laser pulse excitation method, the lower detection limit of Cd Ⅱ 226.502 nm in silicon dioxide, soil, and rice matrices decreased from 372, 332 and 2874 mg·kg−1 to 42, 72 and 37 mg·kg−1, respectively, under photoelectric dual pulse excitation. This study has important reference value for the development of LIBS technology and its application and promotion in the field of soil and food pollution detection.
Improving laser damage resistance of fused silica by organic fluoric acid etching
Chi Fangting, Li Xiaoyu, Li Yuanli, Lü Lina, Peng Hao, Du Zhiyuan
2023, 35: 111005.   doi: 10.11884/HPLPB202335.230131
[Abstract](93) [PDF 8446KB](33)
The laser damage resistance of fused silica optics is of great significance for the stable operation of high-power laser systems. To improve the laser damage resistance of fused silica optics, and to solve the problem of deposition formed by traditional hydrofluoric acid etching, a method based on organic fluoric acid etching is developed. The advantage of organic fluoric acid etching is that the etching product has good solubility, thus reducing the possibility of forming deposition. Organic fluoric acid solution was used for static etching of fused silica optics, and the surface quality, transmittance, and laser damage density of the opticss were characterized and analyzed. The results of surface quality and transmittance show that the fused silica optics after organic fluoric acid etching have less deposition and impurity, indicating that the organic fluoric acid etching is effective in preventing the formation of deposition. The laser damage tests show that the fused silica optics after 6 μm etching have the average laser damage density of 0.26 cm−2, which is close to those treated by advanced mitigation process (AMP2). Organic fluoric acid based etching for improving the laser damage resistance of fused silica optics has opened up a new pathway in enhancing laser loading capacity.
Inertial Confinement Fusion Physics and Technology
Areal density measurement technology for metal foils based on X-ray bent crystal imaging
Si Haoxuan, Xu Hao, Du Huiyao, Yi Shengzhen, Wang Zhanshan
2023, 35: 112001.   doi: 10.11884/HPLPB202335.230161
[Abstract](69) [PDF 3561KB](26)
In view of the measurement requirements of uniformity and areal density parameters of target metal foils, a non-destructive testing technology for high-Z metal foils by obtaining thin film X-ray transmittance and its spatial distribution through a toroidal crystal focusing type X-ray monochromatic imaging device is proposed. This technology not only effectively improves the accuracy of areal density measurement by high-throughput and high-monochromatic imaging, but also realizes high spatial resolution evaluation of thin film uniformity. This paper carries out in-depth research from the aspects of overall scheme design, component preparation and test experiment, and evaluates the influence of various possible factors on measurement uncertainty. The developed toroidal crystal imaging system achieves micro-region resolution better than 5 μm within millimeter scale for 20 keV-level high-energy X-rays, and spectral resolution reaches several eV. The feasibility of the developed technology is verified by surface density measurement experiment of foam gold sample, and relative uncertainty of areal density measurement better than 2% is obtained. This paper provides a new measurement technology for precise non-destructive testing of high-Z target materials for laser inertial confinement fusion, which is also expected to be applied to other fields that require large field of view and high spatial spectral resolution imaging.
Machine vision aided method for the autonomic diagnostic alignments
Xia Liqiong, Chen Ming, Wang Peng, Chen Bolun, Zhang Xing, Wei Huiyue, Yang Pin, Li Yingjie
2023, 35: 112002.   doi: 10.11884/HPLPB202335.230317
[Abstract](74) [PDF 6459KB](21)
In the laser driven inertial confinement fusion experiments, several dozens of diagnostic instruments are needed, located in different sightlines of view. Most of the instruments are required to work inside the giant vacuum target chamber, in distances of centimeters to meters. They are always moved from several meters away, by the general diagnostic instrument manipulator and point the micro target in a precision of about 50 μm. The binocular pointing method is one of the continual alignment methods, which are able to work in the vacuum and in a faraway distance. However, at present this method needs target recognizing by eyes and pointing in a manual operation. Under some situations, such as under low illumination or pointing sightlines with an angle, the target marker may not be accurately recognized, as a result, the precision of the diagnostic alignment degenerates rapidly. In this work, a machine vision aided autonomic alignment method is proposed. The Mask R-CNN algorithm is used to recognize the target marker. Many simulated visual target graphs are created to train the algorithm. The accuracy of the target marker recognizing increases obviously. The error in the test is less than 8 pixels. Furthermore, the relation between the pixel shift in the visual graph and the pointing shift in the coordinate is calibrated in the laboratory. According to the machine vision aided alignment method, the tested alignment precision in pointing direction is estimated to be less than 30 μm, and in axial direction less than 50 μm. With the feedback of the alignment shift, the diagnostic alignment is able to be in an autonomic operation.
High Power Microwave Technology
S band radial beam coaxial grating backward wave oscillator
Wang Zhanliang, Wang Huanyu, He Ziyuan, Lu Zhigang, Gong Huarong, Wang Shaomeng, Gong Yubin
2023, 35: 113001.   doi: 10.11884/HPLPB202335.230198
[Abstract](89) [FullText HTML](20) [PDF 13941KB](34)

High power microwave devices are investigated extensively, because of their potential applications, such as advanced radars, electromagnetic warfare systems. However, low efficiency, enormous volume, huge weight and short lifetime limit their applications. In this paper, a coaxial grating slow wave structure backward wave oscillator (BWO) driven by radial beam is proposed. The focusing system is eliminated in the particle in cell simulation, which can reduce the volume and the power loss in practice. The lifetime of the BWO can also be improved with the thermionic radial beam cathode instead of the explosive emission cathode. After optimization, the BWO driven by 460 kV, 6 kA radial beam can produce 1.2 GW at frequency 3.8 GHz, with the efficiency of 43.5%.

Periodic fluctuation of heater currents in space traveling wave tubes
Li Yanwei, Shang Xinwen, Xiao Liu, Zhao Jiandong, Li Ning
2023, 35: 113002.   doi: 10.11884/HPLPB202335.230181
[Abstract](80) [PDF 17407KB](25)
During the cathode preheating process of a small amount of space traveling wave tubes(TWTs), there is a fault of periodic fluctuations in the heater current. In response to this problem, the range of fluctuation of heater current is estimated by creating the equivalent circuit of heater, and the natural frequency of heater double-helix structure is measured by using the laser vibration, thereby the localization of the problem is completed, and the mechanism of period fluctuation of heater current is analyzed, and the conditions under which the periodic fluctuation occurs are clarified, and the solutions are put forward. Meanwhile, theoretically, the qualitative analysis is conducted on the influence of heater current on the reliability of the space TWTs, and the correctness of the conclusion of reliability influence analysis is verified through experiments.
Ion Beam Science and Technology and Its Applications
Beamlet optics analysis of 400 keV accelerator for CRAFT negative ion based neutral beam injection system
Cui Qinglong, Wei Jianglong, Xie Yahong, Liang Lizhen, Xie Yuanlai, Hu Chundong
2023, 35: 114001.   doi: 10.11884/HPLPB202335.230179
[Abstract](120) [PDF 15400KB](35)
The negative ion based neutral beam injection (NNBI) system is one of the testing or demonstrating systems in the frameworks of Comprehensive Research Facility of Fusion Technology (CRAFT). The object of the CRAFT NNBI system is to research the key physics and engineering issues around the NNBI, and to accumulate experience for future development and operation of the NNBI system for fusion reactor. The beamlet optics character of a negative ion accelerator determines the divergence of the formed beam, and further influences the beam transmission efficiency through the accelerator and the beamline, which is very important to the high-power, high-energy, and long-pulse operation of the NNBI system. Therefore, the ion beam simulation code IBSimu was used to analyze and estimate the physics design of the beamlet optics of the 400 keV accelerator for the CRAFT NNBI system. The IBSimu code has been successfully benchmarked and applied to many negative ion sources. The current design of the electrode aperture has a similar structure of the ITER negative ion source, the calculation results of the beamlet divergence can meet the design requirement. A higher extracted ion current density (between 100 to 300 A/m2) draws a lower beamlet divergence. When properly increasing the extraction gap (between 5 to 7 mm) or acceleration gap (between 88 to 110 mm), there is a decreasing tendency of the beamlet divergence.
Reconstruction algorithm for bunch longitudinal distribution of coherent transition radiation
Yuan Xiaoxiao, Li Jia, Yan Wenbing, Ran Zhaohui, Yang Xin, Zhao Quantang, Zong Yang, Cao Shuchun, Zhang Zimin
2023, 35: 114002.   doi: 10.11884/HPLPB202335.230263
[Abstract](119) [PDF 1393KB](36)
Coherent transition radiation (CTR) spectroscopy has emerged as a highly productive technique for measuring bunch length and reconstructing longitudinal bunch profiles. However, conventional Michelson interferometry is limited to the amplitude measurement of terahertz radiation spectra, rendering it incapable of directly reconstructing the bunch profile owing to the absence of phase information. Currently, the predominant reconstruction methods encompass the Kramers-Kronig (K-K) phase analysis and algebraic iterative reconstruction algorithms. These two algorithms were employed to validate both Gaussian distribution and Gaussian distribution with tail models, respectively. The outcomes obtained from the K-K algorithm exhibit notable uncertainty, whereas the iterative algorithm showcased superior performance in resolving reconstruction ambiguities and mitigating noise interference. Within the framework of the Lanzhou High Energy Electronic Imaging Platform, a specialized Michelson interferometer was meticulously engineered for the precise measurement of CTR interference spectra. Subsequent to two distinct measurements, the acquired data was subjected to reconstruction and comprehensive analysis employing the aforementioned algorithms. As a result, detailed longitudinal beam cluster reconstructions for the electron beam were successfully obtained. These findings constitute a reference for subsequent beam diagnosis and feedback mechanisms within the High Energy Electron Beam Imaging Platform.
Particle Beams and Accelerator Technology
Surface network survey scheme and data processing at High Energy Photon Source
Yan Haoyue, Dong Lan, Wang Tong, Ma Na, Liang Jing, Wang Xiaolong, Men Lingling, Liu Xiaoyang, Lu Shang, Han Yuanying, Yan Luping, Zhang Luyan, Li Bo, Ke Zhiyong, He Zhenqiang
2023, 35: 114003.   doi: 10.11884/HPLPB202335.230117
[Abstract](122) [PDF 1977KB](40)
With the increasing demand on higher precision control of beams in modern particle accelerators, higher requirements are raised for the design and survey of engineering control network. In this paper, the layout and survey scheme of the first-level surface control network for the engineering survey of High Energy Photon Source (HEPS) are introduced in detail. The permanent points of the surface control network are arranged in the tunnel of the particle accelerator building, and the vertical view hole is aligned with the instrument plumb on the top surface of the online station hall, and the observation condition of plane mutual view is formed, the transmission and contact of plane coordinates are realized. In the elevation direction, the communication between the leveling station and the elevation coordinates is realized by means of horizontal viewing holes and doors and windows. Therefore, the three-dimensional view and observation structure is formed, which is unique in the construction of synchrotron radiation light source in China, and effectively ensures the accurate control of accelerator orbit. The scheme that the plane control network adopts the GNSS control network and the corner network of the total station respectively is proposed. The elevation control network adopts the scheme of indoor tunnel ground and outdoor ground level survey scheme. Before the installation of the accelerator tunnel equipment, two surface control network surveys were carried out. The data processing was adjusted in plane + elevation mode, and the accuracy of the measurement process is verified by comparing different survey schemes, and the reliability is verified by comparing the measurement results of two control networks. The average point position standard deviation is 2 mm, which indicates that the survey results are reliable and meet the requirements of subsequent control network survey and equipment installation collimation. The stability of the point is improved by optimizing the design of permanent point marker structure. As HEPS requires high stability of permanent control points, through optimal design and special construction, the ultra-high fine and stable bedrock spacer pile was successfully built in the narrow tunnel space, forming a stable three-dimensional permanent control point for the storage ring. It provides a benchmark for long-term monitoring of beam orbit stability, and provides a reference for the subsequent construction of synchrotron radiation light source.
Development of pointed-mouth slit for neutron engineering material diffractometer at China Spallation Neutron Source
Wang Huaibao, Zhou Liang, Hu Chunming, Li Xiaohu
2023, 35: 114004.   doi: 10.11884/HPLPB202335.230217
[Abstract](79) [PDF 7898KB](27)
The samples of the China Spallation Neutron Source (CSNS) Engineering Material Diffraction Spectrometer (EMD) are very large and have different shapes. The neutron collimation aperture needs to be designed as a pointed-mouth slit to be close to these abnormal components. The main function of the pointed-mouth slit is to provide the beam size is needed by the sample experiment, and ensure that the beam size has high accuracy. The pointed-mouth slit is continuous, and it can be changed according to the experimental requirements. The blade uses enriched boron carbide, which can reduce the deformation of the slit cantilever structure. The slit has a very long mouth, which can approach the special-shaped components and enter into the long tubes. The deformation problem of the cantilever was simulated and analyzed using finite element software. The slit adopts a dual safety design, which can effectively prevent from being damaged by large samples. This slit has been applied to the CSNS engineering material spectrometer. It has made remarkable contributions to residual stress measurement. The application of this slit provides a very important reference for the design of the pointed-mouth slits.
Measurement of transverse phase space based on machine learning
Han Yutao, Li Renkai, Wan Weishi
2023, 35: 114005.   doi: 10.11884/HPLPB202335.230074
[Abstract](111) [PDF 16388KB](47)
Accurate measurement of the transverse phase space distribution of electron beams is of great importance in the design and optimization of accelerators. The computerized tomography theoretically provides the true transverse phase space distribution. However, to understand the details of the distribution more accurately, it is necessary to solve the problems of limited range of rotation angle and insufficient number of projections. In this paper, a neural network model is proposed to address these two problems in the hybrid domains, which combines interpolation and artifact removal neural networks in the sinogram and tomogram domains, respectively. Even with a simple diagnostic beamline and a small number of projections (7), the network model can reconstruct the transverse phase space distribution of beams with high quality. Moreover, since the selection of angles is independent of the normalized phase space, Twiss parameters do not need to be measured. Using the proposed method to measure the transverse phase space improves reconstruction quality to a certain extent and simplifies the measurement process.
Pulsed Power Technology
Remanent magnetic energy recovery method for air-core pulse alternator
Zhang Peng, Li Haitao, Hu Changyong, Kong Lingshuo
2023, 35: 115001.   doi: 10.11884/HPLPB202335.230124
[Abstract](112) [PDF 7737KB](31)
To reduce the energy loss of the air-core pulse alternator and the heating of the field winding, a field circuit topology with the function of recovering residual magnetic energy is proposed. By setting the adjustable inductance in the capacitor branch, the capacitor after the discharge has a reverse voltage, forcing the thyristor and the diode to turn off, and switching the current flow path to realize the transfer of the remaining excitation energy to the capacitor. The circuit uses the thyristor as the main switch, and its high current turn-off capability gives it an advantage in the application of high-power pulse alternator. The working process of the proposed excitation energy recovery circuit is introduced, the influence of residual energy recovery on the energy loss and heat generation of the field winding is simulated and analyzed, and the working principle of the circuit topology is verified experimentally. The results show that the circuit can quickly recover the residual energy in the field winding, shorten the freewheeling time of the excitation current, and reduce the excitation loss and energy loss. The law reflected by the simulation and experimental results is consistent with the circuit principle, which shows the validity of the circuit method.
Nuclear Science and Engineering
Investigation on the application of microtube and shell heat exchanger in energy conversion cycle
Gao Jiao, Ding Wenjie, Huang Hongwen, Guo Haibing, Ma Jimin, Wang Shaohua
2023, 35: 116001.   doi: 10.11884/HPLPB202335.230102
[Abstract](110) [PDF 4471KB](36)
Print circuit heat exchanger (PCHE) is widely used in the present supercritical carbon dioxide (S-CO2) Brayton cycle to support its superiority in compactness when compared with other energy conversion cycles. The maintenance and overhaul of PCHE are hard to be carried out when leakage and fouling appear because of the integral structure of the core. A microtube and shell heat exchanger (MSTE) is proposed in this research. The structure of the MSTE is similar to that of the conventional shell-and-tube heat exchanger except that the tube diameter is reduced to microchannel level. The cross-section area of the flow channel in MSTE takes more counts than that in PCHE, thus the volume and weight of MSTE can be reduced by more than 30% when compared with PCHE under typical design conditions of recuperator and precooler. Sensitivity analysis results show that if the designed recuperator and precooler with MSTE structure are adopted, the inlet temperature of compressor changes less than 1 ℃ when the hot or cold inlet temperature of recuperator increased by about 20 ℃. It can be concluded from the analysis results that the heat transfer capacity of MSTE is sufficient to adjust the general working condition fluctuations of the energy conversion cycle.
Optimal core design analysis for a small mobile helium-xenon cooled solid reactor
Liu Xinyue, Guan Chaoran, Deng Jiaolong, Chai Xiang, He Donghao, Liu Xiaojing
2023, 35: 116002.   doi: 10.11884/HPLPB202335.230253
[Abstract](139) [PDF 6006KB](38)
Due to electricity needs of scenarios such as remote areas and emergency situations, mobile nuclear power sources with high reliability and long life are needed. A conceptual design scheme of a small mobile helium-xenon cooled solid reactor has been proposed in previous work. This study aims to obtain a lightweight and compact core design and improve the design scheme of sliding reflector segments for reliable reactivity control. Firstly, under the design constraints of reactor life and thermal safety, the core geometry optimization analysis was performed using OpenMC, and a design scheme to obtain minimal mass of core was achieved. Secondly, the study analyzed the influence of burnable poison on power distribution and by adding a 2% mass fraction of Gd2O3 to the fuel rods near the reflector region, the radial power factor was reduced from 2.22 to 1.43 at the beginning of life. Finally, by partitioning the sliding reflector, a linear introduction of reactivity was achieved, and it can also ensure the reactor safety in case of accidents. This study provides a certain reference for the design of small gas-cooled solid reactor.
Raman characteristic analysis of oxidation of fuel pellets for intact and leaked pressurized water reactors fuel rods with different burnup
Wang Huacai, Cheng Huanlin, Song Wulin, Guo Lina, Tang Qi, Yang Qifa
2023, 35: 116003.   doi: 10.11884/HPLPB202335.230047
[Abstract](47) [PDF 3622KB](20)
To study the oxidation and phase structure of fuel pellets for both intact and leak pressurized water reactors fuel rods with different burnup, Raman spectroscopy was used to analyze the intact fuel rods with 14 GW·d·t−1 and 41 GW·d·t−1 burnup as well as the leak fuel rods with 14 GW·d·t−1 and 41 GW·d·t−1 burnup. Evaluation of the reactivity and structural changes of the fuels based on different laser powers are provided locally. The results show that the increase in laser power would not cause oxidation of UO2. The intact fuel rod UO2 pellets with 14 GW·d·t−1 and 45 GW·d·t−1 burnup consist of UO2, U4O9 and U3O8, and the oxidation of fuel pellet in peripheral zone is higher than that of the internal area. The leak fuel rod UO2 pellets with 14 GW·d·t−1 and 41 GW·d·t−1 burnup have undergone restructuring and formed columnar grains, which consist of UO2 and U3O8. The increase of burnup and leakage of fuel rods can promote the oxidation of UO2 pellets, but the main phase structure of the fuel pellets will not change.
Analysis of influence of canceling secondary neutron sources ontritium source terms in pressurized water reactors
Wang Qi
2023, 35: 116004.   doi: 10.11884/HPLPB202335.230096
[Abstract](152) [PDF 1704KB](176)
During the normal operation of pressurized water reactors, tritium contributes more than 95% of the total activity of liquid phase effluent from pressurized water reactors, and it is one of the key radionuclides in reactor design and operation. Through in-depth data cleaning and analysis of tritium emission data from eight units operating in the United States with very similar core designs from 2000 to 2019, it is concluded that tritium emission from Sb-Be secondary neutron sources using stainless steel cladding is one of the important sources of tritium source terms for pressurized water reactor units. According to statistics, the average contribution of tritium production from secondary neutron sources in the units is 7.5 TBq·a−1, combined with theoretical calculations, The penetration ratio in line with the current cladding material development and operation management level is 10%−20%. The elimination of secondary neutron sources can reduce the public dose caused by tritium emissions by about 20%, and can also reduce the constraints of tritium source terms on the number of units planned for the plant site. In addition, it also found that significant fluctuations in tritium emissions are significantly affected by concentrated liquid emissions, especially before or during the overhaul of pressurized water reactors in the United States, which will help optimize the management of radioactive emissions from future units.
Advanced Interdisciplinary Science
Temperature-dependent photoluminescence of CH3NH3PbBr3 crystal powder
Yu Hailong, Wu Wenzhi
2023, 35: 119001.   doi: 10.11884/HPLPB202335.230103
[Abstract](68) [PDF 2070KB](22)
In this work, the temperature-dependent behavior of CH3NH3PbBr3 (MAPbBr3) crystal powder is experimentally investigated using steady-state photoluminescence (PL) spectroscopy. Under 405 nm continuous-wave laser excitation, the fluorescence peak is at 560 nm with a full width at half maximum of 123 meV. There is a good linear increase in the luminescence intensity with increasing pump laser fluence, which indicates induced single-photon absorption. The MAPbBr3 crystal powder-induced PL exhibits different temperature-dependent behaviors at temperatures ranging from 80−310 K. As the temperature increases, the photon energy of the line width gets greater and the PL integral intensity gradually decreases because of the enhanced exciton phonon interaction. The peak of the PL spectrum shows a linear blue shift at 80−145 K. There is a very shallow slot around 150 K, while the peak position of the spectrum remains almost constant when the temperature exceeds 150 K. These temperature-dependent induced PL behaviors are mainly due to the contribution of phase transition and thermal expansion from orthogonal to tetragonal phases occurring at around 150 K. In addition, exciton binding energies of about 49.8 meV and longitudinal optical phonon energies of about 60.4 meV are derived from the temperature dependent PL experimental dataset.
Engineering reliability design and improvement for pulsed neutron scintillation detector
Ma Liehua, Chen Shuang, Li Hongtao, Peng Xusheng, Zhang Botao, Li Bo, Wang Cheng, Ai Jie
2023, 35: 119002.   doi: 10.11884/HPLPB202335.230130
[Abstract](67) [PDF 805KB](31)
A series of reliability design work is carried out for a scintillation detector which can detect pulsed neutrons in complex environment. In the design, the inherent reliability of the detector is improved by means of redundant backup of test channels and anti-vibration design. The mission reliability objectives of each component of the detector are defined by means of reliability modeling and index assignment. Through FMECA analysis method, the failure modes and their effects of each component of the detector are studied, and the important component of reliability is determined. The reliability of the detector is further improved by using environmental stress screening test and reliability enhancement test. It is proved that the mission reliability of the pulsed neutron detector with the above reliability design assurance technology is not less than 0.999.