Research on vacuum flashover of insulator in induction cavity
-
摘要: 绝缘问题是高电压、高场强器件和设备中不可回避的问题，是决定器件、设备运行参数和稳定性的重要因素。针对一台直线感应加速器调试中出现的加速腔绝缘环在带束负载情况下的真空沿面闪络现象，进行了分析和研究。分析表明，在排除设计、材料、加工、洁净和真空度等常规异常因素后，导致绝缘环真空沿面闪络的可能因素是电子在绝缘环表面的吸附和累积，绝缘环上累积的电子来源和加速器中加速、传输的电子束的丢失有关。从加速腔工作状态出发，分析绝缘环表面积累电荷和丢失电子束的相关途径，进而提出相应的技术措施，以提高加速腔运行稳定性。
-
关键词:
- 强流加速器 /
- 绝缘环 /
- 真空沿面闪络 /
- 电荷累积 /
- 高能电子诱发等离子体
Abstract: 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. -
图 1 三脉冲电压作用下加速器的加速腔正常工作加速电压波形和发生绝缘环沿面闪络时的加速电压波形
Figure 1. Acceleration voltage waveforms of induction cavity under normal operation and flashover happened
图 2 DARHT I 注入器二极管电压和5 cm和7 cm天鹅绒阴极时的束流波形（测量点在阴极面下游82 cm处）
Figure 2. Waveforms of diode voltage and electron beams with 5 cm velvet cathode and 7 cm cathode
图 3 加速器注入器出口和加速器出口束流
Figure 3. Waveform of electron beam at injector exit and accelerator exit
图 4 多脉冲加速器注入器二极管电压、注入器出口处束流及加速器中段束流波形
Figure 4. Waveforms of diode voltage，electron beam at injector downstream and at 20 m downstream
-
[1] 石金水, 邓建军, 章林文, 等. 神龙二号加速器及其关键技术[J]. 强激光与粒子束, 2016, 28:010201. (Shi Jinshui, Deng Jianjun, Zhang Linwen, et al. Dragon-II accelerator and its key technology[J]. High Power Laser and Particle Beams, 2016, 28: 010201 doi: 10.11884/HPLPB201628.010201 [2] 陈思富, 何佳龙, 王远, 等. 平行平板型真空沿面闪络试验系统的放电诊断[J]. 高电压技术, 2015, 41(12):4027-4035. (Chen Sifu, He Jialong, Wang Yuan, et al. Discharge diagnosis of parallel-plate-type surface flashover test system in vacuum[J]. High Voltage Engineering, 2015, 41(12): 4027-4035 [3] 何佳龙, 彭宇飞, 陈思富, 等. 多脉冲加载下材料的绝缘特性[J]. 强激光与粒子束, 2010, 22(4):927-930. (He Jialong, Peng Yufei, Chen Sifu., et al Characteristic of insulation material under multiple pulses[J]. High Power Laser and Particle Beams, 2010, 22(4): 927-930 doi: 10.3788/HPLPB20102204.0927 [4] 何佳龙, 陈思富, 张篁, 等. 加速器绝缘环真空沿面闪络[J]. 强激光与粒子束, 2016, 28:095101. (He Jialong, Chen Sifu, Zhang Huang, et al. Vacuum flashover of Dragon- II accelerator insulator ring[J]. High Power Laser and Particle Beams, 2016, 28: 095101 doi: 10.11884/HPLPB201628.150950 [5] 何佳龙. MHz猝发率高压脉冲作用下介质真空沿面闪络特性研究[D]. 绵阳: 中国工程物理研究院, 2014.He Jialong. Investigation on vacuum flashover characters of insulated dielectric under MHz bursted high voltage pulse[D]. Mianyang: China Academy of Engineering Physics, 2014 [6] Ekdahl C. Tuning the DARHT long-pulse linear induction accelerator[J]. IEEE Trans Plasma Science, 2013, 41(10): 2774-2780. doi: 10.1109/TPS.2013.2256933 [7] Coleman J E, Moir D C, Ekdahl C A, et al. Increasing the intensity of an induction accelerator and reduction of the beam breakup instability[J]. Physical Review Special Topics—Accelerators and Beams, 2014, 17: 030101. doi: 10.1103/PhysRevSTAB.17.030101 [8] 代志勇, 章文卫, 谢宇彤, 等. 神龙一号加速器束流输运系统研制[J]. 高能物理与核物理, 2007, 31(4):395-399. (Dai Zhiyong, Zhang Wenwei, Xie Yutong, et al. Development of beam transport system of Dragon-I LIA[J]. High Energy Physics and Nuclear Physics, 2007, 31(4): 395-399 doi: 10.3321/j.issn:0254-3052.2007.04.015 [9] Xia Liansheng, Zhang Huang, Yang Anming, et al. Design and initial results of a multi-pulsed intense electron beam source[J]. Review of Scientific Instruments, 2014, 85: 066108. doi: 10.1063/1.4884342 [10] 夏连胜, 杨安民, 张篁, 等. 促发强流多脉冲电子束源物理设计[J]. 强激光与粒子束, 2012, 24(3):706-710. (Xia Liansheng, Yang Anming, Zhang Huang, et al. Design of multi-pulsed electron source[J]. High Power Laser and Particle Beams, 2012, 24(3): 706-710 doi: 10.3788/HPLPB20122403.0706 [11] 代志勇, 杨志勇, 臧宗旸, 等. 神龙二号热阴极注入器束流调试[J]. 强激光与粒子束, 2018, 30:075102. (Dai Zhiyong, Yang Zhiyong, Zang Zongyang, et al. Beam transport tuning of Dragon-II injector with thermal cathode[J]. High Power Laser and Particle Beams, 2018, 30: 075102 doi: 10.11884/HPLPB201830.170098 [12] Ekdahl C, Abeyta E O, Bender H, et al. Initial electron-beam results from the DARHT-II linear induction accelerator[J]. IEEE Trans Plasma Science, 2005, 33(2): 892-900. doi: 10.1109/TPS.2005.845115 [13] 江孝国, 王远, 夏连胜, 等. 神龙二号注入器阳极杆内电子束包络测量技术[J]. 强激光与粒子束, 2017, 29:085101. (Jiang Xiaoguo, Wang Yuan, Xia Liansheng, et al. Measurement technology for electron beam envelope in anode pipe of Dragon-II injector[J]. High Power Laser and Particle Beams, 2017, 29: 085101 doi: 10.11884/HPLPB201729.170073 [14] Jiang Xiaoguo, Wang Yuan, Yang Zhiyong, et al. Time-resolved measurement technique for pulsed electron beam envelope basing on framing and streaking principle[J]. Chinese Physics C, 2016, 40: 017003. doi: 10.1088/1674-1137/40/1/017003 [15] Chen Sifu, Li Xin, Huang Ziping, et al. Design of a high-power linear induction prototype cell at megahertz repetition rate burst mode[C]//International Conference on High Power Particle Beams. Xi’an. 2008: 741-742. -
下载:
点击查看大图
图(5)
计量
- 文章访问数: 950
- HTML全文浏览量: 333
- PDF下载量: 60
- 被引次数: 0
