Low-energy pulsed spark discharge characteristics of pin-plate structure in water
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摘要: 开展了J量级系统储能下电脉冲参数对水中火花放电特性影响研究。驱动源采用参数可调的固态重频纳秒脉冲电源，放电负载为水中针-板结构（间距1 mm），在低重频条件（约5 Hz）下进行实验。通过调节放电参数、拍摄高速阴影图像、光谱诊断以及声信号测量，研究水中脉冲放电的物理特性，得到不同放电参数下放电演化规律及其对声学、光谱特性影响。实验发现：在J量级储能下，放电通道连通两极后，回路电流在几百ns内快速上升至10 A左右，随后缓慢下降，持续50～60 μs。发现预设脉宽对放电影响较大，短脉宽条件下放电会被电源固态开关强制截断出现反向放电，而长脉宽条件下放电通道在后期变得不稳定甚至熄弧中断，出现气泡中二次放电现象。辐射光谱揭示了更多等离子体信息，推断通道电子密度在1018 cm−3量级，随着脉宽增加，特征谱线强度增加，表明活性粒子数密度增加，但粒子种类不变。短脉冲（＜150 μs）作用下产生的脉冲声波的特征宽度在110～150 μs，而当脉宽继续增大，声波脉宽并不继续增加而是保持不变，保持在150 μs左右。研究结果对水中小能量火花放电的机理研究有一定参考价值，为水声学、液相等离子体等领域的应用提供思路。Abstract: The influence of electric pulse parameters on spark discharge characteristics in water was studied. A solid-state repetitive nanosecond pulse power supply with adjustable parameters was adopted. The discharge load was a pin-plate structure placed in water (the distance between the pin and the plate set to 1 mm). The experiment was carried out under low repetitive frequency conditions (approximately 5 Hz). The characteristics of pulse discharge in water were obtained by monitoring discharge parameters, taking high-speed shadow images, collecting optical emission spectrum, and measuring sound pressure. The evolution of pulse discharge with different parameters and its influence on acoustic and spectral characteristics were also obtained. When the energy storage on the order of a few joules after the initial discharge channel was formed between the two electrodes, the circuit current rose to approximately 10 A within a few hundred ns, followed by a rapid and then slow decline with a duration of 50−60 μs. It is found that the preset pulse width has a great influence on the spark discharge characteristics. Under short pulse width conditions, the discharge channel will be cut off by the solid-state switch of the power supply. Under long pulse width conditions, the discharge channel becomes unstable in the late stage and even interrupts the arc,and the secondary discharge appears in bubbles. The radiation spectra reveal more information. With the increase of pulse width, the intensity of the characteristic spectral lines increased, but no new spectral lines were observed. This indicates that the number of active particles increased, and their types remain the same.The channel electron density is estimated on the order of 1018 cm−3. The characteristic width of the pulse sound wave produced by a short pulse (＜150 μs) is 110−150 μs. However, when the pulse width continues to increase, the sound wave pulse width does not continue to increase but remains at 150 μs. It is hoped that this research has a certain reference value for studying the mechanism of small energy spark discharge, and provides ideas for the applications of underwater acoustics, liquid phase plasma and other fields.
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Key words:
- discharge in water /
- plasma /
- image diagnosis /
- spectral diagnosis /
- sound and shock waves
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随脉冲功率技术向高重复频率、长寿命等方向发展，对储能元件和开关元件的稳定性能要求越来越高[1-10]。储能元件，尤其是既要储能又要瞬间高功率释能的元件，自身需要兼顾高电压、大电流和低电感，其稳定性能检测往往具有特殊性；以陶瓷脉冲电容器为例，单体耐压往往在百kV级，实验中为降低直流充电的绝缘压力，经常采用脉冲充电的方式，针对性开展百kV级快速充放电的重复频率测试意义重大。同样，对于开关元件，尤其是基于新型电极材料的气体开关，开展专门的重复频率长时间测试可为实际应用提供有力支撑。因此，本文提出并建立一种固态化瞬态强场测试平台，用于支撑储能元件和开关元件在瞬态强场条件下的稳定性能检测。目前，主要利用平台针对脉冲电容器开展了初步测试。关于脉冲电容器的测试已有较多文献报道，典型的测试是在较长时间尺度内恒电流充电不断提高电压至电容器损坏[11]；或者在一定充放电条件下测试其使用寿命，文献[12]报道了在百ms时间内充放电的重复频率测试研究，文献[13]报道了一种适合测试单个陶瓷电容的百kV实验装置。本文研制的固态化瞬态强场测试平台，利用晶闸管组件作为初级单元控制开关，利用磁开关进行两级脉冲压缩，充分发挥固态化开关无电极烧蚀的技术特点，从而获得较长的运行时间和使用寿命；适用于在百kV，μs时间尺度下对小批量脉冲电容器进行测试，相比于个体独立测试有利于电容元件的性能对比和批量筛选。
1. 系统设计与电路模拟
1.1 系统设计
系统采用初级半导体开关和后级磁脉冲压缩相结合的两级功率压缩方式进行脉冲压缩，再通过高功率磁开关快速放电，从而实现μs时间尺度的快速充放电。固态化瞬态强场测试平台系统框图如图1所示，主要包括高压充电单元、初级单元、闭环磁芯脉冲变压器、磁脉冲压缩网络、复位单元和测试腔体。
功率压缩过程开始于初级单元，使用晶闸管组件将初级单元的能量转换给脉冲变压器，变压器输出脉冲经单级磁压缩网络再次功率压缩后，进一步为测试腔体内的电容样品快速充电，最后，测试腔中的电容样品经磁开关对负载放电。
1.2 电路模拟
利用PSpice软件建立了测试平台电路仿真模型如图2所示，虚线框内为测试腔体。其中：C0为初级单元的储能电容；PSS1为初级单元的晶闸管组件，初级单元产生的脉冲经闭环磁芯变压器XF进行升压，为后级磁压缩网络的电容器C1充电；MS1为磁脉冲压缩网络的磁开关，用于完成进一步功率压缩；Test Cell包括了待测的脉冲电容器网络和用于放电的磁开关MS2；RL是负载等效电阻；电路模型中可饱和电感与可饱和变压器的制作借鉴了子电路建模方法的用户自定义元件[14]；Ir1，Ir2和Ir3是3个直流电源，分别用于复位变压器TF和磁开关MS1-MS2；Lr1-Lr3是复位绕组；Ci1-Ci3和Li1-Li6分别是隔离电容和隔离电感，均用于保护直流电源。
图 2 固态化瞬态强场测试平台的电路示意图Figure 2. Schematic of the solid-state transient intense field test platform各元件的参数设置如表1所示，初级电容C0=2 μF，额定电压为20 kV，次级电容C1=40 nF，额定电压为200 kV，脉冲变压器XF原边漏感约12.7 μH，变比为1∶5；由C0，C1和TF的参数配置可以看出，C1能够获得TF变比以上的充电电压；第一级压缩的磁开关MS1伏秒积为384 mV·s，测试腔内的磁开关MS2伏秒积为32 mV·s，负载阻值为4.7 Ω。
表 1 测试平台电气参数Table 1. Electrical parameters of the test platformvoltage/kV current/mA repetition rate/Hz test cell capacitance (typical)/nF test cell voltage (maximum)/kV core reset current/A 0～20 500 0～10 40 100 2 当初级电容充电11 kV时，得到模拟结果如图3所示。测试电容为40 nF情况下，快速充电电压约54 kV，充电时间约1 μs；测试电容为4 nF情况下，快速充电电压约104 kV。实际应用中，可通过调整待测电容值和负载电阻，使测试装置具有较宽的工作范围。通过以上电路模拟得到了测试平台中各元件的电参数，用于进一步指导测试平台的建设。
图 3 在电容负载情况下测试平台的电路模拟结果Figure 3. Typical simulation results of the transient intense field test platform with different capacitors2. 实验研究
2.1 平台建立
根据系统设计框图和电路模拟结果建立了实验装置（技术参数见表1），系统结构示意如图4（a）所示。实现了一体化设计，连接市电即可进行本地和远程操控运行，使用方便。其中，控制单元、复位单元和充电单元工作于空气介质，初级单元、脉冲变压器、磁脉冲压缩和磁开关工作于变压器油介质，负载电阻是水电阻形式，测试腔体为密闭空间，可密封小于1个相对气压的绝缘气体。测试平台实物如图4（b）所示，体积约1 m3，便于整体移动。
图 4 固态化瞬态强场测试平台Figure 4. Structure of the solid-state transient intense field test platform充电单元的充电电压0～20 kV，充电电流500 mA；初级单元的晶闸管组件采用6个管子串联，每支管子的额定电压4.2 kV，额定电流30 kA；脉冲变压器采用跑道型闭环磁芯实现紧凑结构，在提升初级电压的同时保持较高的能量转换效率；磁脉冲压缩网络中磁开关的绕组为15匝双线并绕结构[15]，磁芯为铁基非晶磁环，具体参数如表2所示。
表 2 铁基非晶磁芯技术指标Table 2. Specifications of the Fe-based amorphous corecore
materialouter
diameter/mminner
diameter/mmheight/mm thickness/μm width/mm Bs/T Br/T insulation per layer/
Vstacking
factor2605SA-1 406 274 20 25 20 ～1.56 ≥1.4 120 ～0.82 为实现稳定测试，平台自身的可靠性非常重要，主要体现在电特性和热特性等方面。所建平台采用晶闸管开关和磁开关相结合的固态化脉冲调制方式，以及储能元件降额使用方式，能够有效解决电特性稳定问题；通过实验测试摸索系统的热特性，从而为确定重复频率长时间运行模式提供支撑。系统在10 Hz重复频率运行1 h情况下，负载方面对测试基本没有影响，因为水电阻的体积约100 L，自身不进行循环且绝热情况下温升约10 ℃；开关方面，由于开关过程中最高等效工作频率约MHz，磁开关发热较少，在油介质中能够实现热平衡。分析认为，限制系统连续运行时间的主要环节可能是晶闸管组件，并且其内部实际温度难以准确监测，在晶闸管结温和壳温未达到热平衡的情况下，功率器件表面温度也不是恒定的[16]。
因此，有针对性地开展了缩比条件下的晶闸管温升实验测试，一种自然空气冷却型的测试器件如图5所示，在通流kA、脉冲底宽10 μs情况下，单管连续工作3.5 h，局部最高温度达到44.9 ℃，温升为26.6 ℃，经分析对应内部PN结温升高约50 ℃，该结果为初步测试结果，可为测试平台重复频率运行提供了一定参考，但更为准确的结果需要专门研究。在测试平台中，晶闸管工作的脉宽和通流条件与前面测试相近，产品手册中说明该型晶闸管安全结温为125 ℃，所以，针对10 Hz重复频率运行1 h的情况，并在油浸环境中使用，能够满足安全使用要求。
2.2 实验测试
利用该平台，针对多种脉冲电容器进行了小批量测试，如图6（a）所示，能够实现相同批次器件的寿命对比和不同批次器件的筛选选型。针对总容值为40 nF的陶瓷电容器，在测试电容器没有损坏情况下，获得的一组典型实验结果如图6（b）所示，测量了电容器的充电电压，以重叠模式显示，电压幅值约50 kV，重复频率10 Hz，运行85 min，稳定可靠性良好，为进一步开展相关测试和器件应用奠定了基础。
图 6 固态化强场测试平台典型测试结果Figure 6. Typical results of the solid-state transient intense field test platform3. 结 论
基于晶闸管组件、闭环磁芯脉冲变压器和磁脉冲压缩等关键技术，研制了1台固态化瞬态强场测试平台。利用该平台，针对多种脉冲电容器进行了小批量测试，针对总容值为40 nF的陶瓷电容器，获得一组典型实验结果：测试电压50 kV，脉冲宽度1 μs，重复频率10 Hz，运行时间85 min（对应51 000个脉冲）。
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[1] 尤特金 Л·А·Ю. 液电效应[M]. 于家珊, 译. 北京: 科学出版社, 1962ткин Л·А·Ю. Электрогидравлический эффект[M]. Yu Jiashan, trans. Beijing: Science Press, 1962 [2] 李元, 温嘉烨, 李林波, 等. 液体介质微/纳秒脉冲放电的特性与机理: 现状及进展[J]. 强激光与粒子束, 2021, 33(6):2-14. (Li Yuan, Wen Jiaye, Li Linbo, et al. Characteristics and mechanisms of streamer discharge in liquids under micro/nano-second pulsed voltages: status and advances[J]. High Power Laser and Particle Beams, 2021, 33(6): 2-14 doi: 10.11884/HPLPB202133.210190Li Yuan, Wen Jiaye, Li Linbo, et al. Characteristics and mechanisms of streamer discharge in liquids under micro/nano-second pulsed voltages: status and advances[J]. High Power Laser and Particle Beams, 2021, 33(6): 2-14 doi: 10.11884/HPLPB202133.210190 [3] 李元, 孙滢, 刘毅, 等. 液电效应及电火花震源的研究现状与展望[J]. 高电压技术, 2021, 47(3):753-765. (Li Yuan, Sun Ying, Liu Yi, et al. Electrohydraulic effect and sparker source: current situation and prospects[J]. High Voltage Engineering, 2021, 47(3): 753-765 doi: 10.13336/j.1003-6520.hve.20210156Li Yuan, Sun Ying, Liu Yi, et al. Electrohydraulic effect and sparker source: current situation and prospects[J]. High Voltage Engineering, 2021, 47(3): 753-765 doi: 10.13336/j.1003-6520.hve.20210156 [4] 卢新培, 潘垣, 张寒虹. 水中脉冲放电的电特性与声辐射特性研究[J]. 物理学报, 2002, 51(7):1549-1553. (Lu Xinpei, Pan Yuan, Zhang Hanhong. The electrical and acoustical characteristics of pulsed discharge in water[J]. Acta Physica Sinica, 2002, 51(7): 1549-1553 doi: 10.3321/j.issn:1000-3290.2002.07.024Lu Xinpei, Pan Yuan, Zhang Hanhong. The electrical and acoustical characteristics of pulsed discharge in water[J]. Acta Physica Sinica, 2002, 51(7): 1549-1553 doi: 10.3321/j.issn:1000-3290.2002.07.024 [5] Graham W G, Stalder K R. Plasmas in liquids and some of their applications in nanoscience[J]. Journal of Physics D: Applied Physics, 2011, 44: 174037. doi: 10.1088/0022-3727/44/17/174037 [6] Malik M A. Water purification by plasmas: which reactors are most energy efficient?[J]. Plasma Chemistry and Plasma Processing, 2010, 30(1): 21-31. doi: 10.1007/s11090-009-9202-2 [7] Sakiyama Y, Tomai T, Miyano M, et al. Disinfection of E. coli by nonthermal microplasma electrolysis in normal saline solution[J]. Applied Physics Letters, 2009, 94: 161501. doi: 10.1063/1.3122148 [8] 孙冰. 液相放电等离子体及其应用[M]. 北京: 科学出版社, 2013Sun Bing. Discharge plasma in liquid and its applications[M]. Beijing: Science Press, 2013 [9] Liu Yi, Zhao Yong, Ren Yijia, et al. Analysis of cavities characteristics of underwater pulsed current discharge[J]. Plasma Sources Science and Technology, 2021, 30: 085005. doi: 10.1088/1361-6595/abf857 [10] 赵勇, 刘毅, 任益佳, 等. 水中大电流脉冲放电的激波传播特性[J]. 高电压技术, 2021, 47(3):876-884. (Zhao Yong, Liu Yi, Ren Yijia, et al. Shock wave propagation characteristics of pulsed high-current discharge in water[J]. High Voltage Engineering, 2021, 47(3): 876-884Zhao Yong, Liu Yi, Ren Yijia, et al. Shock wave propagation characteristics of pulsed high-current discharge in water[J]. High Voltage Engineering, 2021, 47(3): 876-884 [11] 李显东. 不均匀电场下水中微秒脉冲放电过程及机理研究[D]. 武汉: 华中科技大学, 2018Li Xiandong. Research on process and mechanism of underwater microsecond pulsed discharges under nonuniform electric fields[D]. Wuhan: Huazhong University of Science and Technology, 2018 [12] 刘小龙, 黄建国, 雷开卓. 水下等离子体声源的声效率分析与研究[J]. 高技术通讯, 2012, 22(5):552-557. (Liu Xiaolong, Huang Jianguo, Lei Kaizhuo. Analysis and research on acoustic efficiency of underwater plasma sound source[J]. Chinese High Technology Letters, 2012, 22(5): 552-557Liu Xiaolong, Huang Jianguo, Lei Kaizhuo. Analysis and research on acoustic efficiency of underwater plasma sound source[J]. Chinese High Technology Letters, 2012, 22(5): 552-557. [13] Li Handong, Li Yutai, Wang Xinxin, et al. Effect of time interval between pulses on the synthetic sound generated by repetitive nanosecond pulse discharge[J]. Physics of Plasmas, 2021, 28: 073502. doi: 10.1063/5.0050041 [14] 韩若愚, 欧阳吉庭, 李琛, 等. 基于金属丝阵电爆炸的水中声源与冲击波源: CN202010715479.2[P]. 2020-10-27Han Ruoyu, Ouyang Jiting, Li Chen, et al. Underwater sound source and impact wave source based on metal wire array electricity explosion: CN202010715479.2[P] 2020-10-27 [15] 陈聃. 水中等离子体声源放电机理研究[D]. 长沙: 国防科学技术大学, 2016Chen Dan. Research of discharge mechanism of underwater plasma acoustic source[D]. Changsha: National University of Defense Technology, 2016 [16] Brandt S, Schütz A, Klute F D, et al. Dielectric barrier discharges applied for optical spectrometry[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2016, 123: 6-32. doi: 10.1016/j.sab.2016.07.001 [17] Zhang Aman, Li Shuai, Cui J. Study on splitting of a toroidal bubble near a rigid boundary[J]. Physics of Fluids, 2015, 27: 062102. doi: 10.1063/1.4922293 [18] Zhang Zhi, Wu Jian, Li Jilong, et al. Spatial restriction on properties of nanosecond pulsed laser ablation of aluminum in water[J]. Journal of Physics D: Applied Physics, 2020, 53: 475204. doi: 10.1088/1361-6463/abac2c [19] 兰生, 章婧. 基于斯塔克理论的水中电弧放电电子密度光谱诊断[J]. 电机与控制学报, 2015, 19(3):96-99. (Lan Sheng, Zhang Jing. The spectrum diagnosis of electron density caused by spark discharge in water based on Stark theory[J]. Electric Machines and Control, 2015, 19(3): 96-99Lan Sheng, Zhang Jing. The spectrum diagnosis of electron density caused by spark discharge in water based on Stark theory[J]. Electric Machines and Control, 2015, 19(3): 96-99 [20] 刘忠杰, 关根志, 厉天威, 等. 水中放电的光谱测量实验研究[J]. 高电压技术, 2006, 32(5):63-64,72. (Liu Zhongjie, Guan Genzhi, Li Tianwei, et al. Study of discharge inside water bubbles using spectroscopic measurements[J]. High Voltage Engineering, 2006, 32(5): 63-64,72 doi: 10.3969/j.issn.1003-6520.2006.05.019Liu Zhongjie, Guan Genzhi, Li Tianwei, et al. Study of discharge inside water bubbles using spectroscopic measurements[J]. High Voltage Engineering, 2006, 32(5): 63-64, 72 doi: 10.3969/j.issn.1003-6520.2006.05.019 [21] Gigosos M A, González M Á, Cardeñoso V. Computer Simulated Balmer-alpha, -beta and -gamma Stark line profiles for non-equilibrium plasmas diagnostics[J]. Spectrochimica Acta Part B: Atomic Spectroscopy, 2003, 58(8): 1489-1504. doi: 10.1016/S0584-8547(03)00097-1 [22] 黎晗东, 罗海云, 陈喆, 等. 纳秒脉冲空气放电的声学特性实验研究[J]. 高电压技术, 2021, 47(3):840-848. (Li Handong, Luo Haiyun, Chen Zhe, et al. Experimental study on the acoustic characteristics of nanosecond pulsed discharge in atmospheric air[J]. High Voltage Engineering, 2021, 47(3): 840-848 doi: 10.13336/j.1003-6520.hve.20201068Li Handong, Luo Haiyun, Chen Zhe, et al. Experimental study on the acoustic characteristics of nanosecond pulsed discharge in atmospheric air[J]. High Voltage Engineering, 2021, 47(3): 840-848 doi: 10.13336/j.1003-6520.hve.20201068 期刊类型引用(1)
1. 高景明，张瀚文，李嵩，杨希彪，孙艺杰，李典耕，陈绒，任小晶，杨汉武，钱宝良. 磁开关技术及其在高功率脉冲驱动源中的应用. 强激光与粒子束. 2024(11): 55-65 . 
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