“荧光-1”实验装置研制与调试

荧光-1是一套分时放电的大电流脉冲功率实验装置,主要用于反场构形预加热磁化等离子体靶（FRC）形成的物理过程、高温高密度磁化等离子体约束特性等研究,未来可作为磁化靶聚变研究的等离子体注入器。主要介绍该实验装置的构成及其调试实验结果,并简要描述在该装置上开展的FRC等离子体靶初步物理实验进展。调试实验结果表明,荧光-1实验装置初始磁场、磁镜、气体电离、箍缩分系统的放电电流/磁场或感应电场可分别达到110 kA/0.3 T,10 kA/1.2 T,400 kA/0.25 kV/cm,1.7 MA/3.4 T。初步物理实验获得的FRC等离子体靶参数为:靶分界面半径约4 cm、等离子体密度3.51016 cm-3、等离子体温度约200 eV、靶寿命约3 s,同时清晰地观察到了FRC靶形成物理过程。分幅相机获取图像与二维磁流体程序计算图像基本吻合,验证了该装置的物理设计思路,也展示了该装置具备的物理实验能力。     

High Power On-Off Switching with Crossed Field Tubes

A crossed field tube is used as an on-off switch to produce square, 25 ?s wide current pulses at 40 kV and 3.2 kA. Operation is also demonstrated at 120 Hz at an initial 50 kV and 1.3 kA for a ten pulse train. Calculations indicate that continuous operation at over 150 kW of average power is possible with a suitably designed cooling system. A crossed field tube operated in this way has a higher current capability and lower dissipation than hard vacuum tetrodes and could replace such tubes in higher power, lower impedance modulators.     

The Gamitron - A High Power Crossed-Field Switch Tube for HVDC Interruption

A high power crossed-field discharge device has been developed for use as a high voltage direct current interrupter. This device operates at low pressure (0.05 Torr), conducting current at a fixed voltage (~500 V) only in the presence of a weak magnetic field (~100 G) which is substantially perpendicular to the electric field between the electrodes. When the magnetic field is removed, ionization ceases and current interruption results. Physical phenomena occurring in this device have been investigated, including the glow-to-arc transition, gas cleanup, and high voltage breakdown. Based on the results of these investigations, switch tubes have been developed and successfully tested at the 2 kA, 100 kV level, with recovery rates in excess of 2 kV/?s. The availability of such devices will make possible many applications including HVDC circuit breakers, ac current limiters, and practical inductive energy storage.     

Ku波段同轴渡越辐射振荡器的数值模拟

当传统高功率微波器件向高频段拓展时,器件尺寸的缩小将造成空间极限电流及功率容量的减小。基于此提出一种Ku波段同轴结构的渡越辐射振荡器。通过引入同轴结构,器件内部的空间极限电流及功率容量得到了有效提升。调制腔采用三谐振腔结构,与两腔结构相比,调制电子束的能力明显增强。采用高频场软件对调制腔和输出腔进行了冷腔分析。利用2.5维粒子模拟软件对Ku波段同轴渡越辐射振荡器进行了数值模拟,在导引磁场0.6 T、二极管电压392 kV、电流15.2 kA的条件下,在中心频率为14.184 GHz处获得1.2 GW的高功率微波输出,功率转换效率达20%。     

一种多组电极的高功率多脉冲气体开关

 设计了一个有3组电极的开关，给出了开关的结构，分析了多组电极共存的可行性和开关内的电场，利用通用电路模拟软件对通过开关的电流进行了计算。此开关在单组电极导通时，耐电压约为50kV，电流100kA以上，电流脉宽约20μs；在间隔1ms，脉宽为μs级的预触发脉冲触发下，开关能在电感负载中产生间隔为1ms的3个电脉冲，实验测得平均峰值电压约38kV，电流约100kA，脉宽约20μs。     

New Hydrogen Thyratrons for Advanced High Power Switching

Recent advances in high power switching have led to the development of new hydrogen thyratrons operating at high pulse-repetition rate (PRR) and high di/dt with low jitter and long life. Short commutation times, dependent on internal pressure and geometry, and on the method of triggering, combine with inductance less than ? nH/kV to give di/dt on the order of 1012 A/s. Experimental results are in agreement with those predicted by new theoretical models. Operation at peak currents up to 75 kA has been achieved for 10-?s pulses, and much higher currents can be achieved at shorter pulsewidths. Tests at 1 MW of average power have verified thyratron scaling laws at tens of amperes average and kiloamperes rms. Thyratron operation at average power levels far in excess of 1 MW is possible.     

X波段高功率高增益多注相对论速调管放大器设计

针对器件工程应用中的高功率高增益需求，设计了工作在X波段的高功率高增益多注相对论速调管放大器，建立了带输入、输出波导结构的三维整管模型。设计双边对称耦合孔输入腔结构，降低了输入波导对输入腔间隙电场均匀性的影响以抑制非均匀干扰模式；设计采用多腔多间隙群聚结构，降低了输入微波功率的需求，提高了器件放大增益；并且分析设计了多间隙扩展互作用微波提取结构，提高了器件的功率转换效率以及降低输出结构表面电场强度。通过优化设计，粒子模拟仿真实现X波段多注相对论速调管放大器输出微波功率达到3.2 GW，器件放大增益约为60 dB，功率转换效率约为40%。器件验证实验在电子束电压550 kV，电流5.1 kA的情况下，输出功率为0.99 GW，放大增益约为53 dB，转换效率约为35%。     

同轴结构多频相对论返波管的粒子模拟

 提出由双电子注同轴相对论返波管产生双频的设想,采用2.5维相对论全电磁PIC粒子模拟软件,进行了粒子模拟研究。结果表明,在环形相对论电子注电压625 kV,电流24 kA,引导磁场0.772 T的条件下,器件得到了稳定的高功率双频微波输出。其双频微波频率分别为11.5,12.2 GHz,两频率相差0.7 GHz,平均功率约为1.15 GW,平均功率效率7.7%。另外,还通过改变周期数,进一步获得了三频的微波输出,并对结果进行了讨论。     

S波段多注相对论速调管放大器长时间运行研究北大核心CSCD

为了实现高功率微波源低磁场及长时间稳定运行,开展了S波段GW级多注相对论速调管放大器(RKA)的理论模拟设计与实验研究。首先,采用一维大信号非线性理论软件优化设计了S波段4腔多注RKA,找到了器件工作的最佳参数:采用电压550 kV、束流4.7 kA的14注RKA,获得功率1.1 GW、效率43%的输出微波。随后,采用粒子模拟软件对理论设计的束波互作用参数进行了验证,获得了输出功率992 MW,器件效率为37%。最后,根据模拟参数开展了器件重频长时间运行实验研究。采用紧凑同轴Marx功率源驱动S波段四腔多注RKA,在电压530 kV、束流5.4 kA、重频20 Hz、运行时间1 s、引导磁场强度0.39 T、注入微波功率1.7 kW的条件下,获得了功率934 MW、脉宽69 ns的输出微波,束波转换效率33%。在器件重频20 Hz、运行时间10 min条件下,坚实了平均功率889 MW、平均脉宽42 ns的输出微波。该研究结果为S波段RKA的低磁场和长时间运行打下了的技术基础。     

HEM₁₁ mode magnetically insulated transmission line oscillator:Simulation and experiment

A novel magnetically insulated transmission line oscillator(MILO) in which a modified HEM 11 mode is taken as its main interaction mode(HEM 11 mode MILO) is simulated and experimented in this paper.The excitation of the oscillation mode is made possible by carefully adjusting the arrangement of each resonant cavity in a two-dimensional slow wave structure.The special feature of such a device is that in the slow-wave-structure region,the interaction mode is HEM 11 mode which is a TM-like one that could interact with electron beams effectively;and in the coaxial output region,the microwave mode is TE 11 mode which has a favourable field density pattern to be directly radiated.Employing an electron beam of about 441 kV and 39.7 kA,the HEM 11 mode MILO generates a high power microwave output of about 1.47 GW at 1.45 GHz in particle-in-cell simulation.The power conversion efficiency is about 8.4 % and the generated microwave is in a TE 11-like circular polarization mode.In a preliminary experiment investigation,high power microwave is detected from the device with a frequency of 1.46 GHz,an output energy of 43 J-47 J,and a pulse duration of 44 ns-49 ns when the input voltage is 430 kV-450 kV,and the diode current is 37 kA-39 kA.     

Performance and pulse shortening effects in a 200-kVPASOTRONTM HPM source

The PASOTRON^TM is a unique, high-power microwave source that uses a long-pulse (⩽100 μs) plasma-cathode electron-gun and plasma-filled slow-wave structure (SWS) to produce high-energy microwave pulses. The device utilizes no externally-produced magnetic fields; relying on a beam-generated plasma channel in the SWS to transport the beam. Peak powers of up to 5 MW were previously reported in C-band using a rippled-wall waveguide SWS. Scaling experiments indicated that increasing the beam voltage above the 90 kV C-band operation produces significantly higher peak powers. We report results from an L-band PASOTRON^TM BWO designed to operate at 200 kV. The plasma-cathode E-gun built for this device generated beams with voltages of up to 225 kV and currents in excess of 1 kA for pulse lengths of up to 200 μs. The L-band PASOTRON^TM BWO produced 10-20 MW of peak power in the TM₀₁ mode, which was converted in the output to a TE₁₁ mode with fixed polarization. The PASOTRON ^TM also directly produced TE-mode radiation in the 5-10 MW power range with a rotating output polarization, the rate of which can be controlled externally. The peak power and poise width was limited by the stability of the plasma channel at high peak powers and excessive plasma generation in the SWS during the long pulse length     

X波段永磁包装相对论返波管研制

设计了一个X波段相对论返波管,通过对器件结构的特殊设计,提高了器件的Q值,同时增大了电子束与慢波结构之间的耦合阻抗,从而实现器件的低磁场运行以便对其进行永磁包装;当引导磁场强度0.46 T、电子束束压750 kV、束流约5.5 kA时,得到频率9.1 GHz、功率1.24 GW的微波输出。根据模拟结果设计加工了一个磁场强度为0.46 T的小型化永磁磁体,该磁体长48 cm,最大外半径15 cm,总重量约116 kg。开展了永磁包装返波管的实验研究,得到以20 Hz的频率运行1 s时功率900 MW、单次运行时功率940 MW的X波段微波输出。     

准两腔振荡器的理论和实验研究

根据两腔振荡器和返波管的特点提出了准两腔振荡器，其作用机理是两腔振荡器的机理，结构类似返波管.这种结构主要由调制腔组和换能腔组两部分组成，调制腔组实现电子束速度调制，调制后的电子束在通过一个微波场较弱的区间时实现电子束群聚，然后在换能腔组实现电子能量到微波能量的转化，并通过输出结构输出；同时，调制腔组和换能腔组之间存在微波耦合，换能腔组中的一部分微波能量可以耦合到调制腔组，形成一个正反馈回路，在一定条件下实现微波振荡.根据此理论，根据Sinus-700加速器的参数(800 kV，10 kA)设计了一个X波段的高功率微波器件，2.5维Particle in Cell (PIC)程序模拟的效率为28%，微波频率为9.42GHz，微波输出功率为2.25GW，实验上得到的微波输出为微波频率9.40GHz，微波输出功率2.44GW. 关键词： 两腔振荡器 返波管 多波切仑可夫微波器件     

The Jon Beam Opening Switch

Plasma opening switches (POS's) have shown excellent characteristics in pulsed power applications. Proposed POS scaling predicts that the fastest opening time for a given conducted current should occur using a high-velocity low-density plasma as the switch medium. The ion beam opening switch (IBOS) uses a charge-neutral ion beam of 100-300 kV, ? 120 A/cm2 as the switch "plasma." Its velocity of up to 600 cm/?s and density of ~1012/cm3 make this a very fast low-density plasma compared with typical 10 cm/?s and 1013/cm3 POS plasmas. The IBOS has conducted ? 70 kA flowing in a parallel-plate transmission line driven by a 4-? pulser. IBOS opening time is load dependent, being ? 4 ns into a 15-nH load and about twice as long into a 4-? electron diode load. However, switch impedance is not zero during the entire conduction time, rising to ? 3 ? by the time of peak current. Peak current conducted before opening does not vary linearly with either injected ion current or switch axial length. Instead, the conduction current scales with plasma density in the switch, and is nearly independent of switch area until the area is restricted to a narrow (~1 cm) strip.     

脉冲功率技术在短波长气体激光器中的应用

 介绍了脉冲功率技术在离子准分子、准分子和软X射线激光研究中的应用情况。给出了三种激光产生对泵浦源电学参数的要求，并给出实现这些电学参数的实验装置以及实验装置的性能指标。在软X射线激光研究方面，利用10级Marx发生器和Blumlein传输线，建立了最高电流峰值40 kA，前沿为26.6 ns的毛细管放电装置，并实现了46.9 nm激光输出。建立了输出电压600 kV、输出电流20 kA的电子束装置，并作为泵浦源实现了离子准分子光腔效应。为了泵浦S2准分子，采用横向放电方式和低电感放电回路，实现了电压脉冲宽度为29.2 ns的窄脉冲放电。     

低磁场S波段相对论返波振荡器的工作特性

为了实现高功率微波发生器的小型化,开展了S波段低磁场相对论返波振荡器工作特性的研究工作。由于S波段返波振荡器频率低,对应的电子回旋共振磁场强度也很低,因此低磁场条件下面临着电子束传输效率低和束波互作用效率低两大问题。为解决上述问题,采取下列措施:通过加大电子束与器件内壁的距离,提高电子束传输效率;采用较深的慢波结构作为提取腔,实现高束波互作用阻抗;提取腔前采用浅深度慢波结构,使提取腔区域的电子速度与微波相速同步。粒子模拟证明,以上措施有效,在引导磁场强度仅为0.17 T、电子束电压435 kV、电流6.5 kA的条件下,该返波管获得功率为670 MW、效率约为25%的输出微波。相对于常规S波段相对论返波振荡器的磁场系统(B=0.8 T),适用于该返波管的0.17 T低强度磁场系统螺线管外半径下降了20%,能耗下降了约93.8%。     

20GW低阻负载电感储能功率调节装置研究

 对电感储能/电爆炸丝断路开关功率调节系统进行了数值模拟，研制了输出峰值功率大于20GW的小型化低阻负载电感储能/电爆丝断路开关功率调节装置。实验结果表明：以电容器作为初始能源，在6~10Ω电阻负载上输出脉冲电压大于400kV、脉冲电流50~60kA，峰值功率大于20GW，能量转换效率大于30%。     

Investigation of an X-band magnetically insulated transmission line oscillator

An X-band magnetically insulated transmission line oscillator （MILO） is designed and investigated numerically and experimentally for the first time. The X-band MILO is optimized in detail with KARAT code. In simulation, the X-band MILO, driven by a 720 kV, 53 kA electron beam, comes to a nonlinear steady state in 4.0 ns. High-power microwaves （HPM） of TEM mode is generated with an average power of 4.1 GW, a frequency of 9.3 GHz, and power conversion efficiency of 10.870 in durations of 0-40 ns. The device is fabricated according to the simulation results. In experiments, when the voltage is 400 kV and the current is 50 kA, the radiated microwave power reaches about 110 MW and the dominating frequency is 9.7GHz. Because the surfaces of the cathode end and the beam dump are destroyed, the diode voltage cannot increase continuously. However, when the diode voltage is 400 kV, the average power output is obtained to be 700 MW in simulation. The impedance of the device is clearly smaller than the simulation prediction. Moreover, the duration of the microwave pulse is obviously shorter than that of the current pulse. The experimental results are greatly different from the simulation predictions. The preliminary analyses show that the generations of the anode plasma, the cathode flare and the anode flare are the essential cause for the remarkable deviation of the experimental results from the simulation predictions.     

低磁场谐振腔切仑科夫振荡器-锥形放大器的初步实验研究

设计了一种能工作在低磁场高功率的慢波器件,该器件通过谐振腔将切仑科夫振荡器与锥形放大器有机地结合,充分利用电子的能量,实现了高效的微波产生.给出了初步的实验结果,在束流电压450kV,电流2.3 kA,导引峰值磁场0.6T的情况下,得到230 MW,频率为10.33 GHz,模式TM01的微波输出,效率达到23%.实验结果与粒子模拟结果基本吻合.     

紧凑型P波段相对论返波振荡器的粒子模拟

 设计了一种紧凑型P波段相对论返波振荡器,其电动力学结构是由同轴慢波结构和同轴引出结构组成的。同轴慢波结构缩小了器件的径向尺寸;同轴引出结构缩短了器件的轴向长度,且提高了束波作用效率。通过粒子模拟研究了器件内束波作用的物理过程,模拟结果表明：器件具有结构紧凑、束波作用效率高的特点。在二极管电压700 kV,电流7 kA,导引磁场1.5 T时,器件在频率833 MHz处获得较高的微波输出,饱和后输出微波的平均功率达1.58 GW,效率约为32%,器件电磁结构尺寸仅为108 mm×856 mm。