Discharge induced by plasma during high-velocity impact on target plate with gradient potential

Based on the objective reality of gradient potential existence in spacecraft surface caused by charged particles in space plasma environment in the orbiting spacecraft, discharge of spacecraft with surface charging or deep dielectric charging would be induced by debris or meteoroids impacting. In order to simulate the existence of the spacecraft surface potential in the laboratory, method of spacecraft surface segmentation was used, different spacing is reserved between two adjacent surfaces, and resistance is added to create high-potential surface and high-potential gradient as a target in the segmentation of the surface for 2A12 aluminum plate. Potential gradient power supply circuit system, discharge test system and ultra-high speed camera photo acquisition system were built by ourselves, and combining with two-stage light gas gun loading system, we have carried out experiments on high-velocity impact on 2A12 aluminum target with gradient potential. In the experiments, high-potential 2A12 aluminum was used as the target with gaps of 2 mm, 3 mm, 4 mm and 5 mm between high-potential and low-potential 2A12 aluminum, the incidence angle (between projectile flying trajectory and target plane) of 60°, and the impact velocity of about 3 km/s. Voltage probe and current probes were used to acquire discharge voltage and current. The experimental results show that the plasma discharge is generated by forming a discharge channel between high-potential and low-potential target, the gaps with 2 mm and 3 mm evoke primary discharge, and the discharge current increases when the level of spacing decreases; the gaps with 4 mm and 5 mm induce the second discharge, and the discharge current does not change significantly when the spacing between high-potential and low-potential target increases.