Shinya Fukushige

Solar-Array Arcing Due to Plasma Created by Space-Debris Impact

A solar-array paddle has a high probability of a space-debris impact because it has a large area. The space-debris impact on the solar array causes not only mechanical damage but also electrical damage such as solar-array arcing through the local high-density plasma created by hypervelocity impact. In the worst case, Joule heating of the arcing carbonizes an insulation layer, and a permanent short-circuit path is created. This is permanent sustained arc (PSA). However, no PSA caused by space-debris impact in orbit has been reported. This paper evaluates the possibility of PSA caused by debris impact. Hypervelocity-impact tests on solar-array coupons in the condition of pseudopower generation were conducted. We ascertained that a space-debris impact can lead to PSA on the solar array.

Development and Evaluation of a TSLGG— Application of an ETC Gun System to its First Stage

A new type of launcher, ETC-TSLGG, is a two-stage light gas gun (TSLGG) using the technology of electrothermal-chemical (ETC) gun for its first stage. ETC-TSLGG is an improved version of the ETC gun which we had researched previously. It is developed to speed up the projectile velocity and control of variation of delay time from the ignition signal to the projectile launch. It will be used as a projectile launcher in a counter impact. Therefore, launch timing of the projectile is very important. Adjusting charge voltage and inductance of coils in a 10-kJ condenser bank so that variation of delay time is as small as possible, we depressed jitter of launch timing within a microsecond order in ETC-TSLGG. In this study, we investigated the delay time generation process. In order to clarify the operational state, pressure sensors were mounted in the ignition chamber and the pump tube. We measured projectile velocity, delay time, discharge voltage profile, current profile, and pressure profiles at different charge voltage and inductance. It can be said from these profiles that the delay time jitter was stabilized at high charge voltage and low inductance. Moreover, we have demonstrated that the delay time jitter of ETC-TSLGG was 1/100 smaller than that of the conventional TSLGG