1 北京理工大学 物理学院,北京 100081
2 重庆大学 电气工程学院,重庆 400044
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。
水中放电 等离子体 图像诊断 光谱诊断 声波与冲击波 discharge in water plasma image diagnosis spectral diagnosis sound and shock waves 强激光与粒子束
2022, 34(9): 095006
1 北京理工大学 物理学院,北京 100081
2 西安交通大学 电气工程学院,西安 710049
开展了水中铜丝电爆炸引燃铝粉悬浮液的实验研究,将铝粉悬浮液置于有机玻璃管中,同轴心方向穿过200 μm的金属铜丝,经脉冲功率驱动后快速相变发生电爆炸为铝粉爆燃提供反应条件。通过比对不同质量球状铝粉(μm粒径)的悬浮液在相同脉冲电容器储能条件下的放电和冲击波参数,获得了电爆炸驱动铝粉放电特性和冲击波增强效应的规律。实验发现,电爆炸起爆铝粉的冲击波有两个明显的波峰,分别对应于金属丝电爆炸(一次冲击波)和由产物气体胀裂管壁产生的二次冲击波,且铝粉爆燃对二次冲击波的增强效应非常显著,在300 mg铝粉的悬浮液环境中,二次冲击波峰值达到2.77 MPa,是无铝粉添加环境中二次冲击波的2.25倍,冲击波冲量增强了约50%。对不同储能条件下200 mg铝粉的悬浮液环境中金属丝爆的冲击波进行了对比研究,发现随着驱动源储能的增加,电爆炸引发的主冲击波和二次冲击波压力均逐渐增大,600 J时分别达到了3.17和1.91 MPa,冲击波冲量也随储能增加而增加,在600 J储能条件时的冲量为41.12 Pa·s,储能条件约300 J时20.24 Pa·s冲量的2倍。
金属丝电爆炸 冲击波 含能材料 等离子体诊断 脉冲功率技术 underwater electrical wire explosion shock wave energetic materials plasma diagnostics pulsed power technology 强激光与粒子束
2022, 34(7): 075015
强激光与粒子束
2022, 34(7): 075014
强激光与粒子束
2021, 33(6): 065010
Author Affiliations
Abstract
1 School of Physics, Beijing Institute of Technology, Beijing 100081, China
2 State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China
3 Global Energy Interconnection Development and Cooperation Organization, Beijing 100031, China
4 Systems Engineering Research Institute, Beijing 100094, China
Underwater shock waves generated by pulsed electrical discharges are an effective, economical, and environmentally friendly means of stimulating reservoirs, and this technology has received much attention and intensive research in the past few years. This paper reviews the main results of recent work on underwater electrical wire explosion (UEWE) for reservoir stimulation. A platform is developed for microsecond single-wire explosions in water, and diagnostics based on a voltage probe, current coil, pressure probe, photodiode, and spectrometer are used to characterize the UEWE process and accompanying shock waves. First, the UEWE characteristics under different discharge types are studied and general principles are clarified. Second, the shock-wave generation mechanism is investigated experimentally by interrupting the electrical energy injection into the wire at different stages of the wire-explosion process. It is found that the vaporization process is vital for the formation of shock waves, whereas the energy deposited after voltage collapse has only a limited effect. Furthermore, the relationships between the electrical-circuit and shock-wave parameters are investigated, and an empirical approach is developed for estimating the shock-wave parameters. Third, how the wire material and water state affect the wire-explosion process is studied. To adjust the shock-wave parameters, a promising method concerning energetic material load is proposed and tested. Finally, the fracturing effect of the pulsed-discharge shock waves is discussed, as briefly are some of the difficulties associated with UEWE-based reservoir stimulation.
Matter and Radiation at Extremes
2020, 5(4): 047201