Study of Hypervelocity Impingement for Cu Nanoparticles on CuCr Alloy Target Electrodes in Initiating Vacuum Breakdown

The metal particles in vacuum gaps with a strong electric field would be accelerated to hypervelocity and impinge on target electrodes, which could trigger electric breakdown in the vacuum gaps. The objective of this article is to study the hypervelocity impingement phenomena between Cu nanoparticles and CuCr alloy target electrodes based on molecular dynamics (MD) method. The impingement phenomena in the cases of Cu nanoparticle and Cu target, Cu nanoparticle and Cr target, Cu nanoparticle and CuCr interface target with the impact velocities 5, 8, and 10 km/s are studied, respectively. Furthermore, the various effects associated with the hypervelocity impingement and their significance on vacuum breakdown are also discussed. The results show that the impingement could cause severe plastic deformation and thermal ionization on the impacting materials, deform a crater on the target, and release a cloud of metal vapor and ejection of secondary particles in the vacuum gap and it would lead to the vacuum breakdown. The impact materials and the impact velocities would have significant influence on the impingement phenomena and even on the vacuum breakdown initiated by the impingement.