Journals >High Power Laser and Particle Beams
Contents
2019
Volume: 31 Issue 12
17 Article(s)
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[in Chinese]
Simulation analysis and test of periodic focusing system with opening magnetic ring
Zugen Guo, Zhixin Yang, Rujing Ji, Ping Han, Ruifeng Zhang, Qi Wang, Zhanliang Wang, Yubin Gong, and Huarong Gong
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 theThe 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%..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 124001 (2019)
Theoretical analysis of optical path accurate adjustment in femtosecond pulse measurement process
Miao Shen, Yanwen Xia, Jun Dong, Bo Zhang, Zhihong Sun, Zonggui Lu, and Haoyu Yuan
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 samFor 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 121001 (2019)
Simulation and experimental verification of thermal expansion of metal and glass cementing bodies
Guohui Li, Honglai Xu, Rujian Xiang, Yinglei Du, Jing Wu, Zhenjiao Xiang, and Yue Zhang
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 boThe 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 Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 121002 (2019)
New negative coupling structure and its application on substrate integrated waveguide bandpass filters
Qing Liu, Dalong Lü, Chenge Bian, and Dongfang Zhou
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 wTo 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123001 (2019)
Design of broad-band input coupler of W-band TE02 mode gyro-TWT
Zheyuan Wang, and Efeng Wang
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 gyroIn 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123002 (2019)
Wideband matching technology used for predistortion linearization
Yongfei Wang, Peisheng Han, Qing Hu, Xinpeng Chen, and Dongfang Zhou
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 tDue 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123003 (2019)
Design of Ku-band 6 bit digital attenuator of microwave monolithic integrated circuit
Shouli Zhou, Jingle Zhang, Jianmin Wu, Shancheng Zhou, and Yuanfei Cheng
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 0A 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123004 (2019)
Study of 0.8 THz regenerative feedback oscillators
Tianyi Li, Weisi Meng, Pan Pan, Jun Cai, Xianping Wu, Jinjun Feng, and Tiechang Yan
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 waWith 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123101 (2019)
Design and simulation of beam-wave interaction system of 397 GHz clinotron
Siming Su, and Jinjun Feng
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 papClinotron 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123102 (2019)
Analysis on the interference effect of electrostatic discharge of GNSS receiver on aircraft
Yuqing Fan, Erwei Cheng, Ming Wei, Qinglong Zhang, and Yazhou Chen
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 fronAiming 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123201 (2019)
Design of X-band ultra-wide angle scanning phased array antenna
Jiaojun Lu, and Hongchao Wu
–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 c–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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 123202 (2019)
Study on over-current protection of solid-state Marx generators
Junfeng Rao, Tong Zeng, Zi Li, and Song Jiang
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 propSiC 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125001 (2019)
Compressed strong magnetic field confinement effect on alpha particle energy in field-reversed configuration plasma target
Xiaoming Zhao, Chengwei Sun, Qizhi Sun, Yuesong Jia, and Weidong Qin
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 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125002 (2019)
Discharge characteristics of a gas switch triggered by ejected plasma
Mingkang Zhang, Xuandong Liu, Xi Shen, and Chengjun Liang
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 effeHigh 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125003 (2019)
Nonlinear optimization for longitudinal beam injection in diffraction-limited synchrotron light sources
Siqi Shen, Shunqiang Tian, Qinglei Zhang, Xu Wu, and Zhentang Zhao
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 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125101 (2019)
Design of bremsstrahlung target of 4 MeV flash X-ray machine
Hui He, Haijun Yu, Yi Wang, and Wenhua Dai
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 targeBremsstrahlung 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125102 (2019)
Upgrade of CSRe beam diagnostic control system based on EPICS
Min Li, Yonggan Nie, Shengpeng Li, Weilong Li, Jinmei Dong, Yucong Chen, Tiecheng Zhao, Ruishi Mao, Zhiguo Xu, Xincai Kang, Yongchun Feng, Zulong Zhao, Yanmou Wang, Weinian Ma, and Yan Yin
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 presentThe 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..
High Power Laser and Particle Beams
- Publication Date: Jan. 01, 1900
- Vol. 31, Issue 12, 125103 (2019)
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