Experimental research on discharge characteristics induced by hypervelocity impact on split targets with potential gradient

Abstract

Aiming at the reality of different potential differences on the surface of a spacecraft, it is very difficult to obtain a potential difference in the laboratory. In order to disclose the influence of potential difference on discharge, we have segmented a spacecraft surface into different parts with reserved gaps, in which gaps reserved in two adjacent surfaces are added resistances to create a multi-surface with different potential differences, and the low-potential surface as a, impact target in the split targets. In order to disclose the discharge characteristics, it is very vital to establish the charging and discharge systems. Therefore, a circuit system with different potential differences, discharge testing system, and ultra-high speed camera acquisition system are established by ourselves, and combining with a two-stage light gas gun loading system, nine sets of experiments have been conducted about hypervelocity impact on a 2A12 aluminum target with different potential differences. In experiments, gaps of a 2A12 aluminum target are the same among different potential parts in every experiments the gaps are 2 mm, 5 mm and 10 mm and applied voltages are 300 V, 200 V, and 100 V in every group experiment, respectively. The experiments have been performed at the impact velocity of about 3 km/s and the incidence angle of $60^{\circ }$ (between projectile flying trajectory and target plane). Voltage and current probes are adopted to acquire discharge voltage and current during the process of impact. The experimental results show that the discharge induced by impact plasma is produced among high- and low-potential targets, the gaps with 2 mm, 5 mm, and 10 mm can evoke a primary discharge among different split targets, and a primary discharge current peak and discharge duration increase with the increase of the applied voltage at the same gap of split targets. Meanwhile, a secondary discharge is induced at the conditions of the gap for 2 mm and corresponding applied voltage of 200 V as well as 5 mm and 300 V, respectively.