大富豪棋牌游戏

Most CitedMore >

Links

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:
Interaction between laser-driven high-velocity metal granule and gas
Han Xue, Zhang Li, Zhang Yongqiang, Wu Jichuan, Tan Fuli
Accepted Manuscript  doi:
[Abstract](71) [PDF 1049KB](4)
Abstract:
We apply laser-driven launch technique to the case of the interaction between high-velocity metal granule and gas for investigation of high speed gas-solid two-phase flow transport. Optimization of target design and adjustment of laser parameters were used to control the process of laser-driven. Diagnostic tools with high resolving power of space and time were set up to capture the high-velocity granule. The unsteady flow field of the granule is governed by the the 3-D Reynolds averaged Navier-Stokes equations and six degree of freedom ballistic equation. With the implicit Gauss?-Seidel scheme, the code was advanced in time. Results indicated: the laser-driven launch technique was effectual and the shadow photographs of high-velocity granule were taken successful. The aerodynamic drag of high-velocity granule was computed with numerical simulation. The foundation was laid for further research.
Broadband second harmonic generation of spatial chirped pulses
Tao Yudong, Hu Dongxia, Han Wei
Accepted Manuscript  doi:
[Abstract](28) [PDF 735KB](1)
Abstract:
Efficient broadband harmonic conversion has important application value in high power laser. However, it is difficult to achieve the broad bandwidth and high efficiency at the same time in the traditional second harmonic generation (SHG). In this paper, a novel broadband SHG scheme is proposed, which uses the space-time coupling effect to transform the temporal chirped pulse into spatial chirped, and then several spliced crystals are used to achieve efficient broadband frequency conversion. Simulation results show that for the spliced KDP crystal, the conversion efficiency of the fundamental harmonic reaches about 60%, for pulse bandwidth of 30 nm and central wavelength of 1 053 nm. Moreover, the frequency doubled light is still linear and broadband, and can be compressed as the fundamental pulse.
Operation stability improvement for synchrotron light sources by tune feedback system
Wu Xu, Tian Shunqiang, Zhang Qinglei, Zhang Wenzhi
Accepted Manuscript  doi:
[Abstract](38) [FullText HTML](41) [PDF 806KB](2)
Abstract:
Ten Insert Devices (IDs) had been installed in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. The ID gaps were repeatedly adjusted for the scientific experiments during the user time. The residual quadrupole errors beyond the ID feedforward disturbed the beam optics, including the betatron tune deviations that spoiled machine performance and brightness stability. A tune feedback system was developed and implemented in the SSRF storage ring to resolve the deterioration. The tune stability of ±0.001 in 2 weeks was reached. Another important function of this feedback system is finding out slow drift in the power supplies of dipole or quadrupole by observing the correction current changes in the feedback. To prove this feedback’s feasibility, we compared variations of the beam parameters, including the injection efficiency, the beam life-time, the horizontal beam size and the beta-beatings.
Research on Lidar scanning mode
Yuan Guangfu, Ma Xiaoyu, Liu Shuang, Yang Qilong
Accepted Manuscript  doi:
[Abstract](28) [PDF 838KB](2)
Abstract:
Scanning Lidar is widely used in atmospheric remote sensing detection and target capture. In order to realize the effective detection of Lidar, four common scanning modes of Lidar, raster scanning, Lissajo scanning, Spiral scanning and hexagonal scanning, are studied in this paper. The corresponding scanning equation is deduced, and the physical meaning and adjustment method of parameters are discussed. Aiming at the requirement of fine scanning in atmospheric remote sensing detection, the distribution of spot under raster scanning and hexagonal scanning is studied. The leakage rate and overlap rate of two scanning modes are simulated and analyzed. The results show that under the same scanning condition, the leakage area of hexagonal scanning mode is the least. The physical image and scan pattern of scanning control system based on the above research contents are presented. Finally, the characteristics of four scanning modes are summarized, and their application and suggestions are given.
Comparison of insulation properties of several liquid dielectrics under nanosecond pulse
Jia Wei, Chen Zhiqiang, Guo Fan, Li Yaoyao, Qi Yuhang, Chen Yongping, Yang Tian
Accepted Manuscript  doi:
[Abstract](28) [PDF 760KB](1)
Abstract:
Based on the self-developed nanosecond pulsed test platform with output voltage of 30 ns risetime and 100 ns half width, and the standard dielectric strength DC tester, the breakdown characteristics of four liquid dielectrics (transformer oil, glycerol, deionized water and Galden HT200) under DC and nanosecond pulse were experimentally studied and compared. And the following conclusions were obtained: (1)Under both DC and nanosecond pulse, Galden HT200 has the highest breakdown field strength which is more than 40% higher than the transformer oil. (2) Under the nanosecond pulse, the breakdown field strength of Galden HT200 and transformer oil both increased by 6.5-7 times than those under DC. And it took the shortest time(nanosecond scale) for Galden HT200 to breakdown, followed by the transformer oil(20 ns), then glycerol(45 ns) and deionized water(70 ns). (3) After multiple breakdowns, a lot of carbonized discharge products are accumulated at the electrode gap in the glycerol which has the largest viscosity coefficient. However, there are no obvious breakdown traces in the Galden HT200 and deionized water, which both have the smaller viscosity coefficient. But obvious shock waves were observed in the Galden HT200 and deionized water, which make the gap electrodes to loosen.
High-performance multifunctional apparatus for studying secondary electron emission characteristics of dielectric
He Yun, Yang Jing, Miao Guanghui, Zhang Na, Cui Wanzhao
Accepted Manuscript  doi:
[Abstract](31) [PDF 847KB](0)
Abstract:
The paper introduces a high-performance multifunctional apparatus for studying secondary electron emission characteristics of dielectric. The apparatus is equipped with a collector containing three grids and a 30 eV−30 keV electron gun, the secondary electron emission characteristics of dielectric can be measured under ultra-high vacuum, and in-situ XPS spectrometer, heating and argon ion sputtering can also be performed. The paper also introduces the measurement of secondary electron yield by pulse method, gives the measured secondary electron current pulse of gold and Al2O3, the charging saturation time and influence of the thickness of dielectric on the charge amount are obtained by judging the change of the current pulse waveform with time and the number of irradiations.
Electron beam introduction of Ka-band coaxial multi-beam relativistic klystron amplifier
Dang Zhiwei, Li Shifeng, Wang Zhanliang, Huang Hua, Wang Tengfang, Liu Zhenbang, Gong Yubin
Accepted Manuscript  doi:
[Abstract](24) [PDF 995KB](0)
Abstract:
The Ka-band high power microwave coaxial multi-beam relativistic klystron amplifier is a potential device. This paper firstly determines the main factors affecting the efficiency of multi-injection electron beam introduction and preliminary structural parameters through theoretical analysis. Secondly, the Ka-band relativistic multi-beam diode model is established by three-dimensional particle simulation software to optimize the structural parameters. The final efficiency of electron beam introduction can reach 89%. Finally, an experimental study on the generation and transmission of electron beams was carried out to verify the results of particle simulation. Under the condition of electron beam voltage 502 kV, beam current 4.34 kA, axial magnetic induction strength 0.76 T, the electron beam introduction efficiency reached 72%. The electron beam pattern obtained by electron beam bombardment of the nylon target indicates that the shape of the electron beam is not distorted during generation and transmission. The generated electron beam diameter is about 2 mm. The simulation and experimental results show that the designed high-current multi-beam diode can generate high-quality electron beams and achieve efficient electron beam introduction. Provide technical support for Ka-band coaxial multi-reported relativistic klystron amplifiers.
Characteristics analysis of electrohydraulic shockwave
Wu Min’gan, Liu Yi, Lin Fuchang, Liu Siwei, Sun Jianjun
Accepted Manuscript  doi:
[Abstract](26) [PDF 1279KB](0)
Abstract:
Characteristics of electrohydraulic shockwave are the keys to the application of electrohydraulic disintegration of rocks(EHDR), mathematical models are used to characterize the generation and propagation of the shockwave, an integrated experimental platform is established, the measured and simulated results of typical shockwave characteristics are analyzed. The simulated results of characteristics of shockwaves under different charge voltage are given, and the influence of charge voltage on the shockwave characteristics are analyzed. The results show that the peak value and energy of shockwave is 2.67 MPa and 27.30 J respectively, the wave front time is 2.16 μs, the loading rate is 1.24 MPa/μs, when the charge voltage is 11 kV. The peak value and energy of shockwaves increase, the wave front time decrease, the loading rate of shockwaves increase, while the efficiency of electrical energy transfer into shockwave energy decrease, when the charge voltage of capacitor raise. Characteristics of shockwaves can be predicted from the parameters of discharge circuit through the simulation method, which can provide theoretical basis for further study on the morphology and effect of EHDR.
Compact balanced bandpass filters based on multilayered dual-mode substrate integrated waveguide cavities
Lü Dalong, Liu Qing, Zhang Junjie, Zhang Dewei, Zhou Dongfang
Accepted Manuscript  doi:
[Abstract](23) [PDF 1083KB](1)
Abstract:
To design size-reduced balanced bandpass filters (BPFs) with high selectivity, two new multilayered dual-mode substrate integrated waveguide (SIW) balanced BPFs are proposed. Firstly, the characteristic of dual-mode SIW cavity is analyzed in detail. Then, a balanced SIW BPF with balanced input/output (IO) ports locating on the upper dual-mode SIW cavity is proposed, and the lower dual-mode SIW cavity is coupled to the upper one using two crossed slots. Three transmission zeros (TZs) can be produced at any locations. A balanced SIW BPF with balanced IO ports locating on the upper and lower dual-mode cavities respectively is also proposed, and the two cavities are coupled by a slot. Two symmetrical TZs can be produced. Based on the proposed structures, two filters with center frequency of 10 GHz are designed, fabricated and measured. The measured results agree well with simulated ones, which indicates the feasibility of the proposed multilayered dual-mode SIW balanced BPFs with compact size and high selectivity.
Research on the influence of cutting parameters on the frequency characteristics of KDP surface topography
Kuang Liangjie, Pang Qilong, Chen Mingjun, Ma Luqiang, Xu Youlin
Accepted Manuscript  doi:
[Abstract](185) [PDF 1612KB](10)
Abstract:
The influence of cutting parameters on the frequency characteristics of optical crystal surface has been studied. The experiment of single point diamond turning has been adopted to process KDP crystal. The frequency distribution of surface profile has been obtained by power spectral density. The continuous wavelet method is used to evaluate the influence of cutting depth, feed rate and spindle speed on machined surface. The results show that the frequency characteristics reflect the effects of cutting parameters on surface topography. The wavelength and amplitude of mid frequency embody the change of cutting depth and spindle speed, and amplitude increases with the increase of cutting depth and speed. Low frequency reflects the change of feed rate, and the amplitude becomes small as feed rate decreases. High frequency is the manifestation of vibration and material anisotropy in processing. Therefore the analysis of frequency characteristics on surface topography provides a reference value for selecting the optimal process parameters.
Effect of residual polishing particles on the thermal damage characteristics of materials in surface scratches
Guo Wenhua, Tao Ye, Zhang Rongzhu
Accepted Manuscript  doi:
[Abstract](22) [PDF 893KB](0)
Abstract:
A thermal damage analysis model of scratches and residual polishing particles on the optical surface is established. The thermal damage properties of optical materials under such complex defects are studied. The finite difference method was used to calculate the light field modulation and temperature field distribution of the optical material surface at different positions of the polished particles at different scales. According to the surface temperature distribution, the thermal damage threshold of the optical material under the corresponding conditions is achieved. The results show that in addition to the influence of the polishing particle radius on the material damage threshold, when the polishing particles are located at different positions in the scratch width direction, the thermal damage threshold of the material will also change significantly. Among them, the polishing particles in the center of the scratch have the strongest modulation on the light field, and are more likely to cause melting damage of the material.
New type of high power energy calorimeter with full absorption
Zhang Cuicui, Wang Yi, Wang Jianzhong, He Bin, Yu Mingmei
Accepted Manuscript  doi:
[Abstract](77) [PDF 1054KB](2)
Abstract:
In order to solve the problem of the existing HPM radiation field power density measurement system, such as many measurement links, complex system and long cable which can’t adapt to complex electromagnetic environment measurement, a miniaturized and integrated power density measurement system of high-power microwave radiation field is developed in this paper. A antenna-coupler-adapter is used as the front receiver, the back end of the system is coaxial signal processing unit, where the attenuation, power detection and electro-optical conversion is achieved in the shield box, so, the system can be measured and monitored remotely. Meanwhile, modular calibration is applied in the system, which can effectively reduce the measurement uncertainty. The system has 30 dB dynamics, a minimum measurable pulse width of 50 ns and a measurable radiation field power density of 100 MW/m2, the system is compact structure, and is easily to carry, anti-electromagnetic radiation, and power density measurement of GW high-power microwave radiation field in X-band can be realized immediately.
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:
Propagation characteristics of terahertz wave in plasma sheath around air vehicle
Geng Xingning, Xu Degang, Li Jining, Chen Kai, Zhong Kai, Yao Jianquan
Corrected proofs  doi:
[Abstract](178) [PDF 1132KB](10)
Abstract:
In this paper, the plasma electron density and collision frequency are calculated based on the flow field simulation of RAM C-III air vehicle, and an inhomogeneous plasma model is established according to the calculation results. The effects of plasma density, plasma thickness, plasma collision frequency and external magnetic field on the propagation characteristics of terahertz wave in plasma are analyzed using scattering matrix method. The results show that the propagation loss increases with plasma electron density and plasma thickness, while the transmittance decreases first and then increases with the increasing of collision frequency. When an external magnetic field is applied, the propagation characteristics of the left-handed polarized terahertz wave will be improved, while for the right-handed polarized terahertz wave, the application of magnetic field induces an absorption peak, which shifts to high frequency range with the increasing of magnetic induction intensity. This work may make a contribution to solving the problem of communication blackout.
Nitrogen doping experiment of 1.3 GHz superconducting cavity
Dong Chao, Sha Peng, Liu Baiqi, Li Zhongquan, Yang Jisen, Wang Honglei
Corrected proofs  doi:
[Abstract](108) [PDF 712KB](7)
Abstract:
In order to greatly improve the quality factor (Q) of a Nb superconducting cavity and reduce its power loss, we performed high-temperature nitrogen doping (N-doping) on the superconducting cavity, which is the most widely used method in the world. Based on the needs of large-scale accelerators at home and abroad, the Institute of High Energy Physics, Chinese Academy of Sciences, carried out researches on 1.3 GHz 1-cell superconducting cavities, including standard post-processing and N-doping. After data analysis and comparison, it can be found that the Q values of two 1.3 GHz 1-cell fine-grain superconducting cavities have been significantly improved. At the same time, the abnormal behavior of Q value depending on acceleration gradient (Eacc) was observed in low-temperature vertical test, which is called the "anti-Q-slope" phenomenon.
Two-phase streamer characteristics in transformer oil under nanosecond impulses voltages
Wang Qi, Wang Meng, Wang Jue, Yan Ping
Corrected proofs  doi:
[Abstract](125) [PDF 2125KB](0)
Abstract:
To reveal the influence of the formation and development of gas-phase streamer channel on liquid discharge between pin-plane electrodes, a numerical model of the transformer-oil discharge in the pin-plane electrode system is built based on the continuity equations of free charge carriers, which are coupled with the Poisson’s equation. The gas-phase processes during the streamer development process is also taken into consideration, including impact ionization and the increase in the mobility of free charge carriers in the gas-phase relative to the liquid-phase in the streamer channel. The Heaviside function is used to switch the simulation model between gas-phase and liquid-phase. The initial and propagation progress of streamer discharge under nano-second pulse voltage is simulated using the model. Simulating results show that the electric field at the streamer body is significantly reduced and the electric field at the head of the streamer is further enhanced with the addition of such low density gas-phase region. The propagation speed of the streamer in two-phase model is also faster than that of the ordinary liquid-phase model.
High-precision Runge-Kutta method for transmission line equation
Wang Xutong, Zhou Hui, Ma Liang, Cheng Yinhui, Li Jinxi, Liu Yifei, Zhao Mo, Guo Jinghai, Wang Wenbing
Corrected proofs  doi:
[Abstract](33) [PDF 1755KB](0)
Abstract:
This paper presents a high-precision Runge-Kutta (RK) method for solving transmission line equations. This method adopts high-order Taylor expansion in space, which improves the approximation accuracy of spatial differentiation. Compared with the traditional finite element time-domain method, when the number of samples per wavelength is the same, RK method has higher precision. At the same time, according to the Taylor model, researchers use RK method to solve transmission line equation in the external field excitation. The correctness and high precision of the RK method are verified by numerical examples of our study.
The preliminary study of laser-triggered pseudospark switch
Zhou Liang, Zhang Ming, Sun Chengge
Corrected proofs  doi:
[Abstract](132) [PDF 1012KB](2)
Abstract:
Laser-triggered pseudospark switches, also called back-lighted thyratrons (BLTs), are low pressure, high voltage, high current glow-mode switches The feasibility of BLTs is verified. The laser beams with wavelengths of 266 nm and 532 nm were used in the test. In the non-focused mode, the minimum trigger energy for 266 nm laser is 15 mJ, the anode ignition delay time is about 340 ns, and the time jitter is about 40 ns. The minimum trigger energy for 532 nm laser is 83 mJ, the anode ignition delay time is about 420 ns, and the time jitter is about 60 ns. In the focused mode, the minimum trigger energy for 266 nm laser is 4 mJ, when the laser trigger energy is 8 mJ, the anode delay time is 190 ns, the jitter is less than 1 ns. The minimum trigger energy for 532 nm laser is 6 mJ, when the laser trigger energy is 8 mJ, the anode delay time is than 240 ns, the jitter is less than 1 ns. The methods to further reduce the energy of the laser trigger will be studied in the future.
Analysis on nonlinear response of RF filter under ultra wide band pulse environment
Lu Xicheng, Qiu Yang, Wu Jing, Tian Jin, Yang Zhiqiang
Corrected proofs  doi:
[Abstract](192) [PDF 764KB](3)
Abstract:
The experiments reveal, for the RF filter, the out-off-band transfer property under ultra wide band (UWB) pulses is essentially in agreement with that of continous wave (CW). However, for some frequencies in the in-band of the filter, the transfer function of UWB is much larger than 1. Moreover, the oscillating property is found in the time domain response of the filter. Therefore, based on the nonlinear passive intermodulation (PIM) and the Q-value, the response mechanisms of the filter are studied. The PIM of the filter shows nonlinear effects under the two different field strengths, which results in the limited universality of measurement results. Furthermore, the signal through the filter is predicted by making use of the two measured transfer functions. The predicting results under CW pulse are smaller than the measured ones in energy and peak power. In a word the response mechanisms of the filter under UWB pulse does differ from the that under CW pulse, i. e., the measured results of CW can’t be applied for the UWB effect analysis and evaluation.
Analysis and research on new integrated motor-driving and charging topology
Zhang Yaowen, Zhang Zhengquan, Liu Qingxiang, Ou Weili
Corrected proofs  doi:
[Abstract](53) [PDF 924KB](0)
Abstract:
This paper proposes a novel motor-driving charging integrated topology with high-frequency AC link (HF AC-link), soft-switching operation and high-frequency (HF) galvanic isolation, which can apply to the two modes of motor driving control and charging. The topology belongs to a new class of resonant AC-link topology, and its link is composed of a series ac inductor/capacitor(LC) pair.When the topology is working in the forward direction, the driving motor is in the motor driving control state, and the battery is being charged in the backward working period. In this paper, the principle of operation of the two working modes of the new topology is introduced in detail. The effective control strategy is used and the simulation model is built by MATLAB/Simulink software. The integrated topology and control strategy are verified. The simulation results show that the topology works. The charging mode can meet the different voltage requirements of the whole charging phase of the battery; working in the motor driving mode, the stator current exhibits a good three-phase sinusoidal shape in both the acceleration process and the normal working process, and the rotation speed can reach a given value, thereby proving the feasibility of this topology and control strategy.
Study on temperature rise of electromagnetic coil launcher
Xiong Min, Zhang Yadong, Gong Yujia, Zhang Hu
Corrected proofs  doi:
[Abstract](122) [PDF 1235KB](0)
Abstract:
Synchronous induction coil launcher mainly uses pulse current to supply power directly to the coil. The temperature rise of armature and coil will occur in the actual working process, and it is a major factor restricting the development of coil launcher to miniaturization and high speed. In this paper, the temperature rise model of electromagnetic coil is established. For single trigger, Comsol and self-programmed Coilgun are used to calculate, and the corresponding test platform is built to verify the temperature rise. The Comsol method with direct coupling is the most accurate method, and the change of material parameters with temperature can also be considered. The simulation results show that the temperature rise of armature is about 4.2 ℃ and the maximum temperature rise of coil is 7.7 ℃. Because of the limitation of measurement delay and sampling frequency of thermocouple temperature sensor, the armature temperature test curve can not measure the maximum temperature point in the simulation curve, it can record the temperature change curve in the whole test process. The change of temperature and the final stable temperature are basically consistent with that of the simulation. The maximum error is 6.1%, which shows the accuracy of the simulation. This study lays a foundation for subsequent multi-stage coil continuous launching.
Lifetime characteristic of three-electrode field-distortion gas switch of fast linear transformer driver
Li Ying, Jin Jianwei, Chen Li, Sun Fengju, Li Xingwen, Wang Zhiguo, Jiang Xiaofeng, Wu Jian, Li Penghui
Corrected proofs  doi:
[Abstract](103) [PDF 1180KB](4)
Abstract:
Three-electrode field-distortion gas switch is a crucial element of modular fast linear transformer driver (FLTD). Electrode erosion affects the trigger jitter during the lifetime of the switch, which in turn can affect the output characteristics of FLTD. Therefore, studying the impact of electrode erosion on the trigger jitter of the switch is of great significance to optimize the switch structure and predict the switch life. This paper studies the erosion characteristic of intermediate electrode of three-electrode switch, and the electrode materials are stainless steel and brass. The key factors affecting the lifetime of switch are obtained by considering the changing rules of trigger and erosion characteristics, which provides theoretical support for the optimization of the performance of the three-electrode switch. The results show that the erosion area and surface roughness of stainless steel and brass electrodes increase with discharge times. The brass electrode is ablated more seriously and the stainless steel electrode has higher surface roughness. With the increase of discharge times, the breakdown point moves to the electrode edge area, which affects the insulation performance of the switch.
Design of portable resonant voltage doubling capacitor charging power supply
Zhang Yuanyi, Ling Zhibin, Li Xuguang
Corrected proofs  doi:
[Abstract](64) [PDF 891KB](1)
Abstract:
This paper presents the design and verification of a portable resonant voltage doubling capacitor charging power supply with an input voltage of 24 V and an output voltage of 3 kV. According to the characteristic of high voltage ratio, this power supply adopts a topology structure combining the series resonant topology and the voltage doubling rectifier, which avoids the adverse effects of excessive number of turns on the secondary side of the high frequency transformer and excessive distributed parameters. The core components such as high frequency transformer, resonant capacitor and switching device were designed and debugged. The power supply was used to conduct the capacitor charging experiment, and the test results have verified the correctness of the design.
 Cover and Content
《强》刊2019年第12期目录
2019, 31: 120000.  
[Abstract](183) [PDF 1054KB](23)
High Power Laser and Optics
Theoretical analysis of optical path accurate adjustment in femtosecond pulse measurement process
Shen Miao, Xia Yanwen, Dong Jun, Zhang Bo, Sun Zhihong, Lu Zonggui, Yuan Haoyu
2019, 31: 121001.   doi:
[Abstract](216) [PDF 1044KB](18)
Abstract:
For the measurement of single shot femtosecond laser pulse, to describe the influence of incident angle and crystal rotation on the output signal accurately, the third harmonic process is analyzed and deduced. In this article, the range of the angle of incident light is derived and calculated mathematically. At the same time, the relationship between the output autocorrelation signal and the crystal’s attitude is analyzed quantitatively. The results show that, to satisfy the phase matching condition, the minimum value of the incident angle is 30.114°. The output direction of the autocorrelation signal is insensitive to the rotation of the crystal. However, the output intensity is sensitive to the intersection angle of two incident beams. The capacity of the crystal rotation is large, and the thinner the crystal is, the less sensitive it is. Moreover, the time resolution of the correlation signal is determined by the angle between the two incident beams in the crystal, the change of the angle outside the crystal does not change the time resolution. The study has reference value for the precise adjustment of femtosecond laser pulse measurements.
Simulation and experimental verification of thermal expansion of metal and glass cementing bodies
Li Guohui, Xu Honglai, Xiang Rujian, Du Yinglei, Wu Jing, Xiang Zhenjiao, Zhang Yue
2019, 31: 121002.   doi:
[Abstract](161) [PDF 1339KB](13)
Abstract:
The stress of different adhesive bodies were simulated and analyzed at different temperature, and the thermal expansion coefficient of different metals were tested by the Thermal Expansion Instrument. Then, the metals with different thermal expansion coefficient were bonded to the glass separately, then the adhesive bodies were heated in a semi-enclosed space and their deformation were measured by Hartmann. The results show that the simulation data of the adhesive bodies agree well with the experiment data. It can be used to guide the design of thermal expansion matching for different attributes materials.
High Power Microwave
New negative coupling structure and its application on substrate integrated waveguide bandpass filters
Liu Qing, Lü Dalong, Bian Chenge, Zhou Dongfang
2019, 31: 123001.   doi:
[Abstract](143) [PDF 956KB](10)
Abstract:
To design cross-coupled substrate integrated waveguide (SIW) bandpass filters (BPFs) with high performance, a new negative coupling structure is proposed, which is constructed by two coupled lines with shorted ends. The negative coupling structure is analyzed in detail. The stracture which can realize both relatively weak and strong negative coupling strength. The optimization method based on characteristic polynomials and reference zeros and poles of scattering parameters is realized for the filter design. To verify the proposed negative coupling structure, two fourth-order cross-coupled SIW BPFs with the center frequency of 10 GHz based on the optimized coupling matrixes are designed. The first one has a normalized bandwidth of 3% with a negative coupling in one cross-coupling path to illustrate the realization of weak negative coupling strength, and the second one has a normalized bandwidth of 8% with a negative coupling in one main coupling path to illustrate the realization of strong negative coupling strength. Finally, the two BPFs are fabricated and measured. Simulation and measurement results are in good agreement, which demonstrates the feasibility of the proposed negative coupling structure and its application on cross-coupled SIW filters with high performance. The influence of weak disperse cross coupling on locations of transmission zeros is also discussed.
Design of broad-band input coupler of W-band TE02 mode gyro-TWT
Wang Zheyuan, Wang Efeng
2019, 31: 123002.   doi:
[Abstract](160) [PDF 1108KB](11)
Abstract:
In this paper, the input coupler for W-band gyro-TWT is designed to meet the needs of the signal transmission and mode conversion. The input coupler is potential device to be the essential section determining the bandwidth of the whole gyro-TWT. The theoretical analysis of the input coupler of the W-band TE02 mode gyro-TWT is carried out. It is pointed out that one factor affecting the transmission loss of the main mode is that the rise of the miscellaneous modes reduces the transmission coefficient of the main mode, and simulation is done to suppress the miscellaneous modes by optimizing the sizes of the coupling hole, reducing the loss from 3.9 dB to 0.8 dB. According to the simulation sizes processing and cold testing, the final input coupler with 3 dB bandwidth of 7.9 GHz meets the design requirements.
Wideband matching technology used for predistortion linearization
Wang Yongfei, Han Peisheng, Hu Qing, Chen Xinpeng, Zhou Dongfang
2019, 31: 123003.   doi:
[Abstract](107) [PDF 865KB](4)
Abstract:
Due to the gain fluctuation and nonlinear characteristic variation of the TWT amplifier chain, predistorter cannot compensate the nonlinearities at different frequencies within the working band, thus nonlinear mismatch might occur and nonlinearity of TWTA could get worse at some frequencies. The wideband linear match theory of predistorter with TWTA is put forward, and the influence of nonlinear mismatch is discussed. Predistorter cascaded with gain compensation unit can flatten the gain fluctuation and match the nonlinearity of TWTA, truly broaden the linear working band of LTWTA.
Design of Ku-band 6 bit digital attenuator of microwave monolithic integrated circuit
Zhou Shouli, Zhang Jingle, Wu Jianmin, Zhou Shancheng, Cheng Yuanfei
2019, 31: 123004.   doi:
[Abstract](162) [PDF 730KB](9)
Abstract:
A Ku-band 6 bit digital attenuator of microwave monolithic integrated circuit (MMIC) was developed based on GaAs E/D pseudomorphic high electron mobility transistor (pHEMT) process. The 6 bit digital attenuator was made up of six base states. It could obtain maximum attenuation of 31.5 dB with the attenuation step of 0.5 dB. 0.5 dB and 1 dB attenuation bits were realized by adopting simplified T-type structure. In the 16 dB attenuation bit, a switched-path-type topology was employed to improve the attenuation flatness and reduce the additional phase shift effectively. The measurement results show that in the range of 12−18 GHz, the 64-state root mean square (RMS) error is less than 0.25 dB, the phase variation is from −0.5° to +9.5°, the insertion loss is less than 4.9 dB and the input and output voltage standing wave ratios are both less than 1.5∶1. The chip size is 3.00 mm×0.75 mm. The MMIC chip has the characteristics of wide bandwidth, high attenuation accuracy and small size. It can be mainly used in fields such as microwave phased array radar transceiver components and communication.
Terahertz Technology
Study of 0.8 THz regenerative feedback oscillators
Li Tianyi, Meng Weisi, Pan Pan, Cai Jun, Wu Xianping, Feng Jinjun, Yan Tiechang
2019, 31: 123101.   doi:
[Abstract](206) [PDF 1015KB](11)
Abstract:
With the development of terahertz technology, high-frequency and high-power terahertz radiation sources have been the focus of researching all over the world. Based on the requirement of 0.8 THz terahertz wave imaging system, the regenerative feedback oscillator is designed and studied by using folded waveguide slow wave structure(SWS). In this paper, the SWS of 0.8 THz folded waveguide is designed and optimized by using the eigenmode solver in CST Microwave Studio. Then the oscillator is simulated and verified by PIC solver in CST Particle Studio. In the initial exploration stage of THz, regenerative feedback oscillator has the advantage of high feasibility and high output power. The simulation results show that a stable output signal of 60 mW can be generated.
Design and simulation of beam-wave interaction system of 397 GHz clinotron
Su Siming, Feng Jinjun
2019, 31: 123102.   doi:
[Abstract](115) [PDF 1086KB](3)
Abstract:
Clinotron is a modification of the backward-wave oscillator. In clinotron the electron beam is inclined to slow wave structure (SWS). Due to the inclined electron beam, electrons are closer to SWS and can interact with stronger electric field, which leads to a higher output power and interaction efficiency. In this paper, the interaction system of clinotron is designed, and the double corrugated waveguide SWS is applied in clinotron for the first time. The dispersion curves, field distribution and beam-wave interaction are simulated with electromagnetic codes and 3D PIC codes. The result shows that more than 100 mW output power and a 50 GHz tuning bandwidth can be obtained. The simulation results show that the maximum output power is 2.3 W at frequency of 370.5 GHz with beam voltage 7.0 kV, beam current 120 mA and guiding magnetic field of 1.0 T.
Complex Electromagnetic Environment
Analysis on the interference effect of electrostatic discharge of GNSS receiver on aircraft
Fan Yuqing, Cheng Erwei, Wei Ming, Zhang Qinglong, Chen Yazhou
2019, 31: 123201.   doi:
[Abstract](338) [PDF 982KB](14)
Abstract:
Aiming at the problem that the Global Navigation Satellite System (GNSS) receiver is susceptible to ESD, the interference effect of the corona discharge on the surface of the aircraft and ESD generated by maintenance on the receiver are studied. The time-frequency domain characteristics of the ESD is analyzed. The front door coupling experiment of corona discharge to the receiver was carried out using a simulator composed of a needle ball electrode and a high voltage source. It is proved that the radiation field generated by the corona pulse has no obvious interference effect on the receiver. Based on the human body metal ESD model, the experiment of the interference effect of spark discharge on the receiver was carried out. It was found that the surge current easily caused potential fluctuation of the serial port conversion chip of the receiver, and the main loop of the read/write program was stuck. ESD protection should be performed for the serial port.
Design of X-band ultra-wide angle scanning phased array antenna
Lu Jiaojun, Wu Hongchao
2019, 31: 123202.   doi:
[Abstract](147) [PDF 1185KB](8)
Abstract:
–To realize X-band ultra-wide-angle scanning, the paper proposes a novel tightly coupled array antenna unit design, and combines the equivalent circuit to analyze and optimize antenna parameters. With the integrated Marchand balun, dipole and balun can be fabricated on the same PCB, thus reducing antenna’s weight and cost. Introducing the vertical parasitic superstrate and horizontal dielectric layer above the antenna aperture, the two work together to improve the impedance transformation during wide-angle scanning. The results show that the scanning angle ranges up to 80° in E-plane while 70° in H-plane, with an active VSWR<3, in X-band (8–12 GHz). The antenna is simple, compact and easy to fabricate.
Particle Beams Technology
Simulation analysis and test of periodic focusing system with opening magnetic ring
Guo Zugen, Yang Zhixin, Ji Rujing, Han Ping, Zhang Ruifeng, Wang Qi, Wang Zhanliang, Gong Yubin, Gong Huarong
2019, 31: 124001.   doi:
[Abstract](160) [PDF 1081KB](7)
Abstract:
The magnetic ring at the wave port position of the TWT periodic permanent magnet focusing system usually adopts single open magnetic ring. Two different double-open magnetic rings were proposed because of adding waveguide impedance tuning branch at the wave port position. The magnetic field near the central axis of the double-open magnetic ring was analyzed by using the 3D electromagnetic simulation software Opera-3D, and the design method of the periodic magnetic focusing system of double-open magnetic ring was put forward. In order to verify the feasibility of periodic permanent magnet focusing system with double-open magnetic rings, an electronic optical system of E-band folded waveguide TWT was designed and tested. In the traveling wave tube test, the emission current of the electron gun was 83 mA, and the electron beam flow rate of the periodic magnetic focusing system with double-open magnetic rings was 99%.
Pulsed Power Technology
Study on over-current protection of solid-state Marx generators
Rao Junfeng, Zeng Tong, Li Zi, Jiang Song
2019, 31: 125001.   doi:
[Abstract](252) [PDF 959KB](12)
Abstract:
SiC MOSFETs with fast rising time and low switching loss have been gradually used in solid-state pulse generators. In this paper, aiming at protecting solid-state Marx generators from common over-current fault, the damage mechanism of SiC MOSFET is analyzed, and a new driving system with over-current protection is proposed. The drive system not only outputs drive signals with long pulse width, but also provides over-current clamping effect during the whole conducting process of the SiC MOSFET. Based on the relation between gate voltage of SiC MOSFET and drain current, the proposed drive circuit clamps the conducting current amplitude by pulling down the gate voltage of SiC MOSFET with a single sampling resistor and a pair of anti-series zener diodes. Experimental results show that the on-state impedance of the SiC MOSFET remains very low when the conducting current is low and consequently the gate voltage is slightly reduced. When an over-current fault occurs, the conducting current can be quickly clamped through the rapidly rising conducting impedance of the switch since the gate-source voltage is pulled down quickly.
Compressed strong magnetic field confinement effect on alpha particle energy in field-reversed configuration plasma target
Zhao Xiaoming, Sun Chengwei, Sun Qizhi, Jia Yuesong, Qin Weidong
2019, 31: 125002.   doi:
[Abstract](353) [PDF 1227KB](2)
Abstract:
Based on an one dimensional elastic-plastic reactive hydro-dynamic code SSS-MHD, confinement effect, by strong magnetic field during compression of field-reversed configuration (FRC) plasma target by solid liner, on the alpha particle energy transport is studied numerically. Also, investigations on the alpha particles self-heating (including local and non-local) and end loss effects are carried out. In the physical model, plasma energy is divided into three parts as that of DT ions, electrons, and alpha particles. In addition, fusion reaction in thermal equilibrium is taken into account. Numerical results imply that FRC target behaves like rigid rotor during solid liner compression. The compressed strong magnetic field can well define alpha particle energy in O-point area in target center rather than in the axis area, which is helpful for an FRC plasma burning. The non-local self-heating power peak value locates at O-point, but the local self-heating power maximum is beyond O-point. The plasma temperature peak value of local self-heating is about 0.5 times greater than that of non-local self-heating. In the script-off layer (SOL), end loss effect of alpha particle energy increases with the solid liner convergence. Especially in the SOL boundary, peak alpha particle energy loss rate appears.
Discharge characteristics of a gas switch triggered by ejected plasma
Zhang Mingkang, Liu Xuandong, Shen Xi, Liang Chengjun
2019, 31: 125003.   doi:
[Abstract](218) [PDF 1025KB](5)
Abstract:
High speed ejected plasma, generated by the discharge in an actuator, can be applied as a trigger to gas gap switch which is working at low coefficient or with wide gap. This paper studies the influence of working conditions of gas switch on the discharge characteristics of ejected plasma triggered gas switch .The effects of gap distance, gas type, gas pressure, switching coefficient and cooperation mode of trigger pulse polarity and main voltage polarity on the discharge characteristics of ejected plasma triggered gas switch were studied by experiments. The results indicate that the ejected plasma triggered gas switch can be reliably and rapidly triggered with switching coefficient of about 10% . When the gas pressure of N2 in the switch is 0.5 MPa and the gap distance is 5 mm, the delay time and jitter are 11.7 μs and 1.42 μs, respectively. When the distance increases to 18 mm, the probability is reduced, the delay time increases to 19.7 μs. When the switching coefficient increases from 10% to 60%, the delay time decreases from 11.7 μs to 1.1 μs. With the same self-breakdown voltage, high pressure, short gap distance, negative trigger pulse and positive main voltage are better best choices to reduce the delay time.
Accelerator Technology
Nonlinear optimization for longitudinal beam injection in diffraction-limited synchrotron light sources
ShenSiqi, TianShunqiang, ZhangQinglei, WuXu, ZhaoZhentang
2019, 31: 125101.   doi:
[Abstract](176) [PDF 725KB](6)
Abstract:
Storage rings of the next generation synchrotron light sources have quite small dynamic apertures with which transverse beam injection can hardly be efficient. The longitudinal beam injection may be a solution to this problem. To apply a longer kicker pulse, it is necessary to increase time offset of the injected beam to the stored one by reducing RF frequency. The beam with a longer time offset will have a higher momentum deviation due to synchrotron motion, thus full injection of this method requires the storage ring to provide large enough energy acceptance and off-momentum dynamic aperture. A candidate lattice of the upgraded Shanghai Synchrotron Radiation Facility (SSRF-U) was used to nonlinearly optimize the longitudinal beam injection. With the optimal results of a series of RF frequencies, it is found that there is a critical RF frequency below which lowering frequency could not help to lengthen the kicker pulse in a given lattice. The beam injection into the SSRF-U storage ring was simulated and reached high efficiency with its critical RF frequency and optimal sextupole gradients.
Design of bremsstrahlung target of 4 MeV flash X-ray machine
He Hui, Yu Haijun, Wang Yi, Dai Wenhua
2019, 31: 125102.   doi:
[Abstract](165) [PDF 567KB](12)
Abstract:
Bremsstrahlung converter target is one of the key factors for flash X-ray machine. The bremsstrahlung radiation process in which the electron beam impinges on the target is simulated utilizing the Monte Carlo method, by which the influence of the effective target thickness on the exposure is analyzed, the optimal target thickness and the exposure are also obtained for the 4 MeV flash X-ray machine. The damages of target impacted by the electron beam are compared and discussed for various electron energy deposit density from different sources, such as 12 MeV LIA, Dragon accelerators and 4 MeV flash X-ray machine. The results show that the tantalum distributed target may be the satisfactory solution for the bremsstrahlung target of 4 MeV flash X-ray machine.
Upgrade of CSRe beam diagnostic control system based on EPICS
Li Min, Nie Yonggan, Li Shengpeng, Li Weilong, Dong Jinmei, Chen Yucong, Zhao Tiecheng, Mao Ruishi, Xu Zhiguo, Kang Xincai, Feng Yongchun, Zhao Zulong, Wang Yanmou, Ma Weinian, Yin Yan
2019, 31: 125103.   doi:
[Abstract](315) [PDF 1063KB](7)
Abstract:
The experimental Cooling Storage Ring (CSRe) of the Heavy Ion Research Facility in Lanzhou (HIRFL) provides high-quality beam for high-precision mass measurement, atomic physics and other experimental studies. Consequently, accurate measurement of beam parameters is the prerequisite for physical experiments. At present, the control system of CSRe has been upgraded to the EPICS architecture. This paper introduces the current status of the beam diagnostics control system based on EPICS which is affiliated with the accelerator control system. Moreover, some of the beam parameters are measured and analyzed by the upgraded beam diagnostics control system. According to the test results with beam at CSRe, the beam position control system can measure the turn-by-turn position of the injected beam. Furthermore, the calculated turn-by-turn position results show that there is a certain degree of oscillation during the injection process, which affects the injection efficiency directly. The beam current measurement system can achieve precise measurement with DCCT by upgrading a high-resolution data acquisition card, in addition, the D event trigger has been integrated into the beam current control system for receiving the trigger and synchronized information from the virtual accelerator. The upgraded control system is running stably and can measure the beam parameters since the upgrade in 2018 and has been integrated into the graphical user interface (GUI) of the accelerator control system.

Conference topicMore >

Wechat: qjgylzs

Digital Publishing Platform