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Just Accepted manuscripts are peer-reviewed and accepted for publication. They are posted online prior to technical editing formatting for publication and author proofing.
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Experimental research of monochromatic X-ray microscopy
Chen Liang, Xu Jie, Li Wenjie, Liu Hanwei, Wang Xin, Mu Baozhong
Accepted Manuscript  doi: 10.11884/HPLPB202032.190486
[Abstract](26) [PDF 1071KB](2)
Based on the diagnostic requirements of high spatial resolution and high energy spectral resolution in the implosion compression stage of laser inertial confinement fusion (ICF), a large field of view and monochromatic imaging system is proposed, which combines KB microscope and diffractive crystal. Under the laboratory condition, the grid is backlight imaging by using the Fe target X-ray tube, with KB microscope and high oriented pyrolytic graphite (HOPG). The imaging results after the crystal energy selection show that the field of view of the system can reach 800 μm, and the resolution of high-resolution area imaging is 37 μm. The results show that the energy resolution of the system is 28, which verifies the monochromatic performance of the system. The system takes into account the large field of view, spatial resolution and energy resolution, and has an important application in the research of hot spot structure and mixing effect in the experiment of implosion compression stage.
Influence of the surface sand blasting treatment on the vacuum surface flashover characteristics of the PMMA insulator
Guo Yuewen, Liu Wenyuan, Huo Yankun, Ke Changfeng, Tang Yunsheng, Duan Li, Chen Changhua1
Accepted Manuscript  doi: 10.11884/HPLPB202032.190464
[Abstract](6) [PDF 0KB](0)
Surface roughening treatment on insulators is an important way to improve their vacuum surface flashover characteristics. However, flashover voltages of the insulators with the same roughness show big deviation because of the poor uniformity of the surface rough structure and bad repeatability of the surface roughening method. To improve the uniformity of the surface rough structure and the stability of the voltage-withstand of the vacuum insulators, sand blasting roughening treatment on the surface of the cylindrical PMMA insulators was studied. First of all, the cylindrical insulators were sprayed on the rotating platform. With the collision of the spherical micro SiO2 particles carried by the high-speed airflow, rough structure was fabricated on the surface. After the corrosion of the HF acid, residual SiO2 particles were removed leaving homogeneous rough structure on the surface. The changes of the surface morphology were studied by Scanning Electron Microscope and the surface roughness of the treated insulators was tested on the surface roughness meter. Surface flashover characteristics of the sand-spray PMMA specimens were tested on the short-pulsed high-voltage platform. The test results indicated that homogeneous surface rough structure was prepared by the sand blasting treatment and the surface flashover voltages of the treated insulators were improved steadily. Compared with the untreated PMMA specimens, flashover voltages of the sand blasting insulators were improved approximately 80%.
Study on mechanism of effect of different experimental conditions on laser -induced plasma
Wang Li, Zhou Yu, Fu Yuanxia, Xu Li
Accepted Manuscript  doi: 10.11884/HPLPB202032.190455
[Abstract](21) [PDF 955KB](0)
Under normal pressure and temperature, aluminum alloy in air was excited by Nd:YAG nanosecond laser with wavelength 532 nm. The collection and photoelectric conversion of the plasma emission spectrum are realized by a high-resolution spectrometer and an ICCD. In this paper, the influences of laser energy, ICCD gate delay and lens-to-sample distance (LTSD) on the spectral intensity and plasma electron temperature are studied, and its physical mechanism is studied. It is demonstrated that the spectral intensity and electron temperature increase with the increase of laser energy at the fixed ICCD gate delay and LTSD. The calculated results show that when the laser energy increases from 20 mJ to 160 mJ, the atomic spectral line Al I 396.15 nm, Mg I 518.36 nm, and the Mg II 279.54 nm spectral line intensity of ion spectral line are 12.83 times, 6.45 and 10.56 times higher than that of 20 mJ, respectively. At the fixed laser energy and LTSD, when the ICCD gate delay changes in the 100−4 000 ns, the spectral intensity and plasma electron temperature decay exponential with the increase of ICCD gate delay. With the same ICCD gate delay and laser energy, the influence mechanism of LTSD on plasma parameters was studied by using a focusing lens with focal length of 75 mm. It demonstrates that the lens-to-sample distance has a considerable impact on the spectral intensity and plasma electron temperature. The results indicate that the change of the spectral intensity is consistent with that of the plasma electron temperature. The curves appear two peaks at the position of 73 mm and 79 mm respectively, and the values reach their maximum at 73 mm.
Optical element defect online detection method based on camera array
Zhang Wenxue, Wang Jihong, Ren Ge
Accepted Manuscript  doi: 10.11884/HPLPB202032.190444
[Abstract](411) [PDF 1057KB](0)
The focusing method can be used to achieve continuous change of the focal length, so that the optical components at different object distances can be detected online. However, the focusing process is complicated and requires high accuracy of the focusing displacement. Defects of optical components within the depth of field cannot be distinguished, making it difficult to achieve real online detection. Therefore, this paper proposes an online detection method for optical component defects based on camera arrays. First, the imaging model of the camera array is established, and the expressions of digital refocusing and the expressions of spatial resolution are given. Then MATLAB is used to simulate the camera array imaging process and digital refocusing process. Finally, experimental verification was conducted. The camera was driven by a two-dimensional stage to image the surface defects of multiple optical elements at different object distances, and an array camera image was obtained. The digital defect refocusing algorithm was used to obtain the surface defect distribution of optical elements at different object distances information. The experimental results show that the online detection technology of optical component defects based on camera array can simultaneously detect the optical components located in the depth of field range. This method has certain application value in the online detection of optical component defects.
Dual band-notch ultra-wideband multiple-input multiple-output antenna with high isolation
Wang Lili, Du Zhonghong, Yang Hailong, Han Xueni, Xi Xiaoli
Accepted Manuscript  doi: 10.11884/HPLPB202032.190443
[Abstract](143) [PDF 1583KB](2)
This paper presents an ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna, which has high isolation and double band-notch in the UWB band. The MIMO antenna consists of two half-cutting UWB antenna units which have high isolation (S21>25 dB) because of the use of a novel fence-type decoupling structure on the bottom plate of the antenna. In addition, two “L”-shaped slots are etched on the antenna radiation patch, and the characteristic of the double band-notch are realized. The interference of the 802.16 WiMAX(3.2-3.7 GHz) and the WLAN(5.15-5.85 GHz) signal to the antenna system is suppressed, respectively. The experimental results show that the antenna has high isolation and a low envelope correlation coefficient (ECC<0.004) in the UWB band. The first notch band is 3.0-3.7 GHz and the second notch band is 5.1-5.8 GHz, which effectively suppresses the interference of WiMAX and WLAN signals.
Design of square pulse forming network with adjacent mutual coupling inductors
Wang Chuanwei, Li Hongtao
Accepted Manuscript  doi: 10.11884/HPLPB202032.190429
[Abstract](26) [PDF 1256KB](1)
For the application requirement of compact and miniaturized pulse source, the design technique of the quasi-square wave pulse forming network with adjacent mutual coupling inductors is studied. Firstly, the network optimization technique based on the univariate search method is introduced, and the values of the inductance and capacitance and the analytical expressions of quasi-square wave are obtained. Then the equivalent decoupling circuit of the network with adjacent mutual coupling inductors is deduced. Based on the backtracking algorithm, the method for calculating the values of each element in the network is given finally. In the case of equal capacitance and constrained capacitance, the parameters of each element in the network are given. The numerical results show that the ideal quasi-square-wave pulse with a certain width flat-top can be produced by using the designed PFN with adjacent mutual coupling inductors. The ingenious design based on mutual coupling inductance is beneficial to the design of compact quasi-square wave pulse forming network.
Design of a non-orthogonal symmetrical strip beam position monitor
Qian Mengxiang, Wu Fangfang, Zhou Zeran, Zhou Tianyu, Lu Ping, Sun Baogen
Accepted Manuscript  doi: 10.11884/HPLPB202032.190425
[Abstract](113) [PDF 1135KB](2)
This paper introduces the approach to design a stripline beam position monitor(BPM) for the project of "THz High-flux Material Physical Property Testing System", which is hosted by National Synchrotron Radiation Laboratory. Due to the non-orthogonal symmetric vacuum chamber at the exit of the undulator, two kinds of stripline BPMs with rectangular and racetrack vacuum chamber respectively are considered as an option, and compared with the traditional BPM with circular vacuum chamber. The modeling and simulation are based on the boundary element method via Matlab. The simulation results show that the sensitivities of BPMs with rectangular and racetrack vacuum chamber are improved by 30%, the impedance matching errors are reduced by 20%, and the beam position fitting errors are reduced by 80%, compared with the traditional BPM with circular vacuum chamber. Considering the accuracy of processing, the stripline BPM with rectangular vacuum chamber is more suitable for this project.
A 2 G/s sampling rate, 20 GHz bandwidth master-slave track-and-hold amplifier in 0.13 μm SiGe BiCMOS technology
Zhang Guifu, Zhou Jie, Liu Youjiang
Accepted Manuscript  doi: 10.11884/HPLPB202032.190421
[Abstract](179) [FullText HTML](34) [PDF 1727KB](1)
A fully-differential master-slave track-and-hold amplifier (MS-THA), with 20 GHz bandwidth is designed and fabricated using 0.13 μm SiGe BiCMOS technology. The MS-THA employs conventional switched-emitter-follower (SEF) as track-and-hold core circuit, Cherryhooper circuits as band-boosting of input buffer and output buffer. To verify the validity of the above circuits, a single-stage THA is designed together with the MS-THA. Operating with a single +3.3 V supply, 0 V input direct-voltage, 2 G/s sampling and −3 dBm input power, the MS-THA achieves a single-ended spurious free dynamic range (SFDR) of less than −23.5 dB at frequency of up to 20 GHz, and total power consumption of about 300 mW.
A beam energy feedback forultrafast electron diffraction
Zhang Junqiang, Li Lin, Liu Yajuan, Jiang Tao, Xiao Chengcheng, Gu Qiang, Xiang Dao
Accepted Manuscript  doi: 10.11884/HPLPB202032.190415
[Abstract](166) [PDF 1506KB](3)
Ultrafast electron diffraction (UED) facility is located in Shanghai Jiao Tong University, driven by a linear electron accelerator, has a photocathode RF gun. Sometimes an RF gun arc might happens during the accelerator running, causes a cavity detuning and beam loss, then result in a beam energy change. It will need a long time to return to previous beam energy, which influences user’s utilization. An energy feedback is applied to low level RF(LLRF) system after improvement of amplitude-phase loop, using a real-time feedback of the beam center position to regulate the output amplitude of LLRF, ensures the stability of beam energy and RF gun accelerating filed. A long period of stability testing indicates, beam energy can returns to its original position value quickly after arc happens, energy jitter is improved from 4.293 3×10−4 (RMS) to 2.855 7×10−4 (RMS), which realized a long term stability of beam energy.
Design of new quick control power protection system of EAST
Wu Xu, Wang Linsen, Wu Yibing, Sheng Zhicai, Chen Tao, Li Ya
Accepted Manuscript  doi: 10.11884/HPLPB202032.190404
[Abstract](173) [PDF 1801KB](1)
Aiming at the problems that may arise in the work of the AC-DC-AC converter of the new fast-control power system of the Experimental Advanced Superconducting Tokamak (EAST), a control and protection method for each link is proposed. Based on in-depth research on the protection mechanism of fast control power in the field of nuclear fusion, and combination with the needs of nuclear fusion devices, a surge current suppression circuit, a voltage protection circuit, an overcurrent protection circuit, an overt-emperature protection circuit, an energy leakage protection circuit, and a crowbar were designed. Compared with the traditional protection method, the scheme has a wide protection range, strong reliability and high security. The experimental results show that the power protection system can ensure safe and reliable exit of the power supply in the event of a sudden failure, and effectively protect the superconducting magnets and power components of the superconducting Tokamak experimental device from damage, verifying the correctness and effectiveness of the designed scheme.
Magnetic flux expulsion effect of 1.3 GHz superconducting cavity
Mi Zhenghui, Yang Jisen, Sha Peng, Dong Chao, Wang Honglei, Zhai Jiyuan, Lin Haiying, Zheng Hongjuan, Liu Baiqi, Sun Liangrui, Zhang Xiangzhen, He Feisi, Pan Weimin
Accepted Manuscript  doi: 10.11884/HPLPB202032.190398
[Abstract](127) [PDF 1122KB](7)
The research of magnetic flux expulsion of 1.3 GHz single-cell superconducting cavity has been carried out with a new set of high precision magnetic measuring and compensating system, combining with 2 K vertical test system of IHEP. The magnetic field at the equator of cavity can be measured with the system and compensated to less than 5.0×10−8 T. The magnetic flux expulsion effect of superconducting cavity under different surface temperature gradient is measured and analyzed. The rf performance of the cavity pinned with magnetic flux is tested, and the sensitivity of superconducting cavity resistance to magnetic flux pinning and the surface resistance of superconducting cavity under different electric field gradients are studied accordingly. The results show that the developed high precision magnetic field measuring and compensating system can meet the research needs of magnetic flux expulsion of superconducting cavity. Higher surface temperature gradient of superconducting cavity is beneficial to the magnetic flux expulsion. The sensitivity of flux pinning resistance increases with the increase of electric field. The research has also laid a foundation for the development of superconducting cavity.
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:
Design of a high-precision and widely tunable bounded-wave electromagnetic pulse simulator
Zhou Kaiming, Li Zhengdi, Deng Jianhong
Corrected proofs  doi: 10.11884/HPLPB202032.190373
[Abstract](130) [PDF 720KB](5)
This paper introduces a high-precision and continuously tunable medium bounded-wave electromagnetic pulse simulator, which adopts a widely tunable, automated novel high voltage pulse source of compact size with fast rise time. Based on fiber transmission automation control is realized, anti-jamming problem is solved and HEMP simulation ability is promoted. Parameters of the simulator are: the rise time about 2.5 ns, FWHM about 23 ns, working volume 4 m×4 m×5.8 m, output continuously tunable electric field from 0.2 kV/m to 60 kV/m.
New-type periodical permanent magnet focus system for G band extended interaction klystron
Wang Zicheng, Wang Yuankun, Qu Zhaowei
Corrected proofs  doi: 10.11884/HPLPB202032.190364
[Abstract](154) [PDF 1179KB](3)
This paper proposes a new-type periodical permanent magnet (PPM) focus system, each half period of which is composed of 1 magnetic pole and 5 permanent magnets, and the first, the third and the fifth magnets have reverse magnetization with the second and the fourth magnets. Besides, any two magnets spaced half period have inverse magnetization with each other. The new-type PPM focus system is modeled and calculated by MTSS2018, the results show that the axial component Bz of the magnetic induction intensity on the axis has conspicuous amplitude of the third and the fifth space harmonics, and Bz rises steeply after it reaches zero, so Bz has a profile very approximate to the periodical rectangular shape. An electron gun under the condition of the above calculated Bz is calculated by MTSS2018 too, a beam with 22 kV of voltage, 215 mA current and 0.08 mm of maximum beam radius is obtained, which meets the demand of G band extended interaction klystron (EIK). In the calculations the peak value of Bz is only 1.2\begin{document}$ \sqrt 2 $\end{document}BB (subscript B is Brillouin magnetic field), it suggests that the new-type PPM focus system focuses the beam effectively even if it has a relatively lower peak value of Bz than the conventional PPM focus system does.
Preliminary exploration of MagLIF concept and feasibility analysis on PTS facility
Zhao Hailong, Wang Ganghua, Wang Qiang, Zhang Hengdi, Xiao Bo, Kan Mingxian, Yang Long
Corrected proofs  doi: 10.11884/HPLPB202032.190352
[Abstract](129) [FullText HTML](70) [PDF 1222KB](3)
Magnetized Liner Inertial Fusion (MagLIF) concept has promising potentials for future energy source (Phys.Plasmas, 2014, 21:072711), it is widely applicable to large-scale pulsed power generators such as the Primary Test Stand (PTS) facility (10 MA, 100 ns). In this context, we’ve developed a zero-dimensional (0D) MagLIF simulation code basing on magneto-hydrodynamic (MHD) equations and Deuterium-Tritium (DT) fusion models. Relationships between fusion products and initial setups (magnetic field Bz0, preheat temperature T0 and so on) are explored using this code, results show optimal parameters existing under given inputs, which are very helpful for future experimental designs. Specifically, according to our simulations, critical driving current (>21.2 MA) is essential for fuel (50∶50 DT) energy to reach breakeven, which infers that PTS facility may not be suitable for integrated MagLIF experiments. Series of calculations are performed to confirm this inference, and more practical aluminum liner experiments are proposed and designed.
Cover and Contents
Cover and Contents, High Power Laser and Particle Beams, No 4, Vol 32, 2020
Editorial Office
[PDF 2808KB](7)
Feature Issue on Accelerator
Basic types and technological implementation of charged particle accelerators
Chen Sifu, Huang Ziping, Shi Jinshui
2020, 32: 045101.   doi: 10.11884/HPLPB202032.190424
[Abstract](873) [PDF 2097KB](48)
The modern particle accelerators have developed greatly over the last 100 years. This article provides an overview of all main types of particle accelerators. Simple charts are given to exhibit conceptual and technological evolutions of major particle accelerators. It also briefly introduces the basic types, fundamental principles, technological approaches, and typical technical features of various types of particle accelerators.
Summary of application of stretched wire technology in accelerator alignment and survey
Yuan Jiandong
2020, 32: 045102.   doi: 10.11884/HPLPB202032.190259
[Abstract](492) [PDF 1141KB](8)
To study the application and development of stretched wire technology in accelerator alignment and survey, the principle of stretched wire technology is summarized firstly, then the development history of stretched wire alignment method in accelerator is reviewed, and the latest development trend of stretched wire alignment method is introduced. Finally, the advantages and disadvantages of various alignment methods and their suitable environments are discussed, and the development differences between domestic and foreign alignment methods are compared. The development direction of the stretched wire alignment method is pointed out, and the direction of the accelerator alignment and survey is given.
Measurement signal processing technology for magnetic axis of solenoid based on pulsed tuat-wire method
Jiang Xiaoguo, Yang Xinglin, Jiang Wei, Liao Shuqing, Zang Zongyang, Liu Yunlong, Long Quanhong, Li Jiayuan
2020, 32: 045103.   doi: 10.11884/HPLPB202032.190431
[Abstract](176) [PDF 1089KB](4)
In measurement of magnetic axis of solenoid, there are some key difficulties to overcome, such as precision measurement of tuat-wire vibration and position, reducing measurement signal distortion, and separative data processing for offset and tilt signal in magnetic axis of solenoid. One kind of signal detect and measurement principle of extracting the useful faintness signal via subtracting the high offset level signal from the total measurement signal is adopted to meet the above need. The method of constant current driving the detector is also adopted to obtain more stable and anti-jamming signal. The measurement system has been developed for directly obtaining the pure vibration signal of the tuat-wire. The problems of obtaining completely exact measurement signal by simply using an AC coupling amplifier or band-pass filter are resolved and the faint signal can be obtained without aberration. The influence produced by tilt and ups-and-downs in low frequency component of base line signal is eliminated ulteriorly. The separative data processing for offset and tilt signal is also achieved to some extent. The measurement sensitivity has been improved maximumly by about an order of magnitude.
Research on vacuum flashover of insulator in induction cavity
Xia Liansheng, Chen Sifu, Shi Jinshui
2020, 32: 045104.   doi: 10.11884/HPLPB202032.200011
[Abstract](63) [PDF 1092KB](3)
Flashover across the insulator in induction cavity with electron beam load once occurred frequently, which affected the performance parameters and stability of the high voltage high current devices and equipment. This paper studies the vacuum surface flashover across the insulator in the induction cavity of a linear induction accelerator under debugging. After excluding design and fabrication of the insulator as well as cleanness and vacuum degrees, it is found that the electrons from the plasma induced by high energy electrons interacting with the gas adsorbed on the inner cavity wall might play the key role of flashover. These thermal electrons move randomly and some of them will reach and stay on the insulator surface for some time, and flashover happens when high electric field is applied across the insulator with accumulated electrons.
Nitrogen doping experiment of 1.3 GHz superconducting cavity
Dong Chao, Sha Peng, Liu Baiqi, Li Zhongquan, Yang Jisen, Wang Honglei
2020, 32: 045105.   doi: 10.11884/HPLPB202032.190141
[Abstract](426) [PDF 882KB](19)
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.
Digital self-excited vertical test system of superconducting cavity
Yang Jisen, Pan Weimin, Wang Honglei, Liu Jiaji, Wang Muyuan, Zhou Quan, He Feisi, Sha Peng, Lin Haiying, Wang Qunyao, Wang Guangwei, Mi Zhenghui
2020, 32: 045106.   doi: 10.11884/HPLPB202032.190320
[Abstract](205) [PDF 1016KB](11)
Vertical test is an important method for characterizing the performance of superconducting cavities. We designed an superconducting cavity vertical test system based on digital self-excited algorithm and the technology of low-level radio frequency, which could improve the vertical test efficiency of superconducting cavities. The RF front-end and clock distribution system of the vertical test system adopts the second up-and-down conversion scheme. To some extent, the working frequency of the digital self-excited loop of the vertical test system can be set flexibly, and the working bandwidth of the test system is increased. The test results of the pass-band frequency of the 1.3 GHz 9-cell superconducting cavity show that the vertical test system has strong frequency resolution (<800 kHz) to ensure the smooth progress of the multi-cell superconducting cavity pass-band test.
Operation stability improvement for synchrotron light sources by tune feedback system
Wu Xu, Tian Shunqiang, Zhang Qinglei, Zhang Wenzhi
2020, 32: 045107.   doi: 10.11884/HPLPB202032.190270
[Abstract](480) [FullText HTML](244) [PDF 1018KB](7)
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.
Development of dynamic power control system in proton therapy facility
Li Hairong, Jiang Geyang, Jin Lin, Li Qiannan, Li Rui, Shen Liren
2020, 32: 045108.   doi: 10.11884/HPLPB202032.190442
[Abstract](201) [PDF 989KB](4)
A high-speed real-time dynamic power control system based on an open source platform has been developed to satisfy the multi-platform energy extraction requirements of the main loop dynamic power supply in a proton therapy facility. The control system uses a Beaglebone based open-source platform as the top-level hardware interface, the controller with Field Programmable Gate Array (FPGA) as the core as the underlying hardware interface, and uses a distributed Experiment Physics and Industrial Control System (EPICS) for remote control. This system can transmit the output reference current waveform data of any dynamic power source in real time, and controls the dynamic power source to output according to the preset current waveform combined with the timing system and the interlocking system, and realizes the energy extraction of multiple platforms. Experimental results show that the control system can achieve a maximum of 100 000 instructions per second and zero error rates for millions of data transmissions. In addition, the system structure is flexible and extensible, and it can be served as a universal control platform.
High Power Laser and Optics
Research on lidar scanning mode
Yuan Guangfu, Ma Xiaoyu, Liu Shuang, Yang Qilong
2020, 32: 041001.   doi: 10.11884/HPLPB202032.190382
[Abstract](539) [PDF 979KB](16)
Scanning lidar is widely used in atmospheric remote sensing detection and target capture. To realize the effective detection of lidar, this paper studies four common scanning modes of l​​​​​​​idar: raster scanning, Lissajo scanning, spiral scanning and hexagonal scanning. 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 these 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 smallest. The physical image and scan pattern of scanning control system based on the above research are presented. Finally, the characteristics of these four scanning modes are summarized, and their application and suggestions are given.
Linewidth of femtosecond laser two-photon polymerization multiple-rapid-scanning
Tong Weiyang, Wang Zhengling
2020, 32: 041002.   doi: 10.11884/HPLPB202032.190089
[Abstract](119) [PDF 1058KB](8)
Using the theory of free radical concentration fluctuation combined with the effect of optical tweezers, this paper studies the linewidth of femtosecond laser two-photon polymerization multiple-fast-scanning processing theoretically. According to the relationship between the change of free radical concentration and time in the two-photon photopolymerization processing, considering the influence of the optical tweezers on the free radical distribution range, it obtains the formula of the linewidth of multiple-rapid-scanning processing. It also presents the relationship between linewidth and scanning speed, laser power, and interval time. The results can be regressed to the general formula of single-scanning and are in good agreement with the experimental results in the literature. The study provides a new idea for studying the femtosecond laser two-photon processing to obtain a smaller processing linewidth, and provides a theoretical basis for the femtosecond laser multiple-rapid-scanning processing.
ICF and Laser Plasma
Density diagnosis based on ps-duration-pulse X-ray backlighting for fast ignition compression
Bi Bi, Zhou Weimin, Shan Lianqiang, Wei Lai, Liu Dongxiao, Zhang Feng, Tian Chao, Deng Zhigang, Yuan zongqiang, Wang Weiwu, Lu Feng, Wu Junfeng, Cai Hongbo, Ren Guoli, Wu Fengjuan, Li jin, Chen Tao, Yang Yimeng, Zhang Faqiang, Yang Lei, Cao Leifeng, Gu Yuqiu
2020, 32: 042001.   doi: 10.11884/HPLPB202032.200050
[Abstract](136) [PDF 1145KB](9)
To provide significant parameters for fast ignition coupling efficiency and density diagnosis for higher compression, a ps-duration X-ray backlighter has been produced with ps-duration laser on Shenguang-Ⅱ updated facility. The radiation properties such as backlighting image resolution and the photons arriving at the image plate have been successfully measured. Based on the conformed conditions, density diagnosis of an indirectly-driven fast ignition target using ps-duration backlighting has been carried out. The obtained short-pulse backlighting radiography shows that the imploded shell shape agrees well with that of simulation and the areal density exceeds 50 mg/cm2. The short-pulse backlighting radiography also shows the hydrodynamic instability which might be caused by the asymmetric compression. Further investigations and attempts to improve implosion performance to a higher density are in progress.
High Power Microwave
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
2020, 32: 043001.   doi: 10.11884/HPLPB202032.190192
[Abstract](290) [PDF 1172KB](4)
This paper firstly determines the main factors affecting its 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%. 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.
High-frequency characteristics of half rectangular ring helix slow wave structure
Xia Wei, Wei Wanghe, Wei Yanyu, Lu Min
2020, 32: 043002.   doi: 10.11884/HPLPB202032.190359
[Abstract](123) [PDF 1282KB](3)
A novel half rectangular-ring helix slow-wave structure (SWS) is proposed for the design of wide bandwidth and high power traveling-wave tubes. The numerical calculation by 3D electromagnetic simulation software HFSS shows that proper dispersion and coupling impedance can be obtained by reasonably setting the geometrical parameters of the SWS. Meanwhile, compared with the half circular ring helix slow wave structure, slight variation in dispersion and remarkable improvement in coupling impedance have been observed in the numerical calculation of the half rectangular ring helix SWS. The half rectangular-ring helix slow-wave structure has the combined advantages of flatten dispersion, high interaction impedance, easy fabrication and convenience for interaction with sheet beam.
Complex Electromagnetic Environment
Design and implementation of semiconductor multi-physical parallel computing program JEMS-CDS-Device
Li Guangrong, Zhao Zhenguo, Wang Weijie, You Chunguang, Zhou Haijing
2020, 32: 043201.   doi: 10.11884/HPLPB202032.190264
[Abstract](126) [PDF 1469KB](6)
Aiming at the research requirements of multi-physical effects mechanism of devices in complex electromagnetic environment, a parallel computing program for semiconductor multi-physics effects, JEMS-CDS-Device, is developed. This paper introduces the architecture design and implementation technology of JEMS-CDS-Device. The program is based on the unstructured grid parallel framework—JAUMIN. It uses the finite volume method (FVM) to discretize and uses the Newton method to get fully coupled solution of the “electric-carrier transport-thermal” problem. The program which adopts the “kernel + algorithm library” form architecture, supports 2D/3D unstructured mesh, and can solve problems of tens of millions of degrees of freedom parallelly. It supports extended development of physical effect equations, discrete algorithms, material physics models, etc.
PCIe electromagnetic interference analysis and optimization design based on co-simulation of field and circuit
Yang Hui, Song Hang, Xiao Xia
2020, 32: 043202.   doi: 10.11884/HPLPB202032.190360
[Abstract](118) [PDF 1030KB](7)
In this paper, the rationality of Electromagnetic Compatibility(EMC)design of Printed Circuit Board (PCB) is evaluated in advance through electromagnetic simulation. The purpose of this method is to reduce the chances that the Electromagnetic Interference (EMI) of PCB does not meet GMW 3097 standard in EMC test. Firstly, the 3D electromagnetic field simulation of the Peripheral Component Interconnect express (PCIe) module on the PCB is performed. Then the field simulation is dynamically linked with the circuit simulation of the Simulation Program with Integrated Circuit Emphasis (SPICE) model of chip on the PCIe module, so that the co-simulation of field and circuit is performed. According to the experimental test, the accuracy of this simulation method is within 6 dBμV, which satisfies the deviation of PCB processing technology and the uncertainty of the experimental test. Thus, this simulation method meets the accuracy requirements. Therefore, the EMI of PCB can be evaluated and the PCB design can be optimized by this simulation method. After the 33 Ω resistors on the PCIe module was replaced by magnetic beads, the EMI of the PCB at 1.6 GHz is reduced by 13.4 dB. According to the 1-m method specified in the CISPR 25 standard for testing, the EMI of PCB becomes −3.4 dBμV, which is lower than the GMW 3097 standard requirement. Therefore, the effectiveness of this measure is verified.
Particle Beams Technology
Effects of different sequential neutron/gamma irradiation on current gain of bipolar devices
Wang Kai, Lü Xueyang, Wu Kunlin, Feng Jiaming, Fan Xiaoqiang, Li Junjie, Yang Guixia, Lu Yi, Qiu Dong, Zou Dehui
2020, 32: 044001.   doi: 10.11884/HPLPB202032.190333
[Abstract](137) [PDF 1037KB](5)
In this paper, CFBR-II fast neutron reactor (China's second fast neutron pulse reactor) and Co-60 device are used to carry out experiments on different sequential neutrons/gamma irradiated bipolar transistors. Under the condition that the collector-emitter voltage is constant, the variation curve of the bipolar transistor current gain with the collector current is measured, and the influence of different irradiation order of neutron/ gamma on the current gain of the bipolar transistor is studied. The experimental results show that when the collector-emitter voltage is constant and the collector current is extremely low, the current gain degradation of the bipolar transistor is relatively large, and the current gain increases with the collector current. The degradation of the current gain of the bipolar transistor caused by the gamma irradiation after the neutron pre-irradiation would be greater than that of the neutron irradiation after the gamma pre-irradiation, and the difference is more obvious in PNP transistor than in NPN transistor. This paper presents a preliminary discussion on the related mechanism.
Pulsed Power Technology
Comparison of insulation properties of several liquid dielectrics under nanosecond pulses
Jia Wei, Chen Zhiqiang, Guo Fan, Li Yaoyao, Qi Yuhang, Chen Yongping, Yang Tian
2020, 32: 045001.   doi: 10.11884/HPLPB202032.190338
[Abstract](1168) [PDF 2509KB](7)
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 pulses were experimentally studied and compared. 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 that of 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 were 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 loose.
Characteristics analysis of electrohydraulic shockwave
Wu Min’gan, Liu Yi, Lin Fuchang, Liu Siwei, Sun Jianjun
2020, 32: 045002.   doi: 10.11884/HPLPB202032.190356
[Abstract](325) [PDF 1426KB](7)
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 pressure 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 decreases, the loading rate of shockwaves increases, while the efficiency of electrical energy transfer into shockwave energy decreases, when the charge voltage of capacitor rises. Characteristics of shockwaves can be predicted from the parameters of discharge circuit via simulation, thus to provide theoretical basis for further study on the morphology and effect of EHDR.
Nuclear Science and Engineering
Development of ion source discharge chamber for the 5 MW neutral beam heating line on HL-2M device
Wei Huiling, Cao Jianyong, Yu Peixuan, Zou Guiqing, Zhou Hongxia, Yang Xianfu, Zhou Bowen, Luo Huaiyu, Geng Shaofei
2020, 32: 046001.   doi: 10.11884/HPLPB202032.190275
[Abstract](122) [PDF 1296KB](7)
To construct a 5 MW neutral beam heating beamline for HL-2M device, the development of the discharge chamber of the hot cathode arc discharge ion source for neutral beam heating was carried out. The neutral beamline contains four sets of 80 kV/45 A/5 s ion sources, and the discharge chamber design index is 850 A/5 s. Firstly, the electromagnetic studio in CST software was used to simulate the cusp magnetic field of the discharge chamber with specific geometric structure, and the cusp magnetic field distribution was obtained, which verified the rationality of cusp magnetic field layout. To solve the problems in the process of the discharge chamber and the localized arcing in the experiment, the structure of the discharge chamber was improved. The side wall of the discharge chamber changed from 40 rows of cusp magnets to 7 rings of cusp magnets, the cathode structure changed from the filament plate structure to the ceramic kovar structure, and a ceramic shield was added between the discharge chamber and the accelerator. Normal arc discharge was obtained in both the cathode plate discharge chamber and the cathode ceramic kovar discharge chamber. The final shaped discharge chamber adopted 7-ring cusp magnets and ceramic kovar cathode structure. The arc discharge index of the 5 MW neutral beamline ion source was achieved in the final shaped discharge chamber. The arc discharge time was close to 5 s, and the maximum arc discharge current reached 1 000 A.
A passive efficiency calibration method with Monte Carlo simulation in segmented gamma scanning
Zheng Honglong, Tuo Xianguo, Gou Jiayuan, Wu Yao, Zuo Wei, Guo Yufei, He Lin, Liu Yanfang, Huang Cong, Yang Linfeng, Liu Wei
2020, 32: 046002.   doi: 10.11884/HPLPB202032.190416
[Abstract](134) [PDF 1053KB](14)
In this work, an efficiency calibration function model is presented to calculate the efficiency of segment in segmented gamma scanning (SGS) for 200 L nuclear waste drum. Discrete SGS efficiencies are simulated with MCNP for different densities and gamma ray energies. Parameters of function are determined by using multivariate nonlinear regression method with the efficiencies. The SGS efficiency calibration function is constructed to calculate the efficiency matrix. Aluminum silicate with density of 0.310 g·cm−3, wood fiber of 0.595 g·cm−3, point sources 137Cs with activity of 3.110×105 Bq and 60Co of 1.371×105 Bq are used to construct samples of drum for SGS analysis. Result shows: for the extremely heterogeneous radioisotope distribution of only a point source placed at 8 different positions in the drum, errors of reconstructed activities are −37.68%~31.52%. Overall, the reconstructed activity is in agreement with the true activity. This method effectively and accurately achieves SGS efficiency calculation and reconstruction of activity.