强流加速器水介质形成线放电或击穿形成的冲击波对陶瓷真空界面具有破坏作用。为获得该冲击载荷的信息,应用通用软件ANSYS/LS-DYNA建立了一种水下爆炸有限元模型,将电弧放电等效为爆炸源,模拟得到了冲击波传播时序、压力历史曲线及陶瓷板的加速度响应;为验证模型的有效性,应用“针-板”电极水开关在输出电脉冲40~50 ns、幅值100~300 kV可调的10级陡化前沿Marx发生器上开展了电水锤缩比实验研究。实测了不同击穿电压下冲击波峰压、波速和主脉冲宽度,并依据经验公式计算了放电沉积能量和冲击波能量,平均约17%的间隙放电能量转换为冲击波机械能。对冲击波能量与峰压关系进行了拟合,并与数值模拟结果进行了比较,二者变化趋势基本一致,量级上吻合较好。

Pulsed discharge in water produces transient shockwaves which are harmful to the ceramic interface in accelerators. In this paper,with a self-consistent underwater explosive approach,a finite element model was set up to investigate the shockwave behaviors,and the pressure-time history and ceramic mechanical response to shockwaves were presented. In order to get the pressure profile and verify the calculation models,a small-scaled water switch test was conducted based on a 10-stage Marx generator (40~50 ns pulse duration,100~300 kV amplitude). The variations of peak pressure,shock velocity and main pulse width under different breakdown conditions were measured. According to the calculation of empirical formulas,about 17% of the discharge energy was transformed into the mechanical energy of the shockwave. The relationship between peak pressure and shock energy was also figured out and the experimental formula has a close approximation to the simulation result.