Preliminary Measurements of ESD Propagation on a Round Robin Coupon

The propagation dynamics of spacecraft electrostatic discharge (ESD) flashover plasmas have been a topic of increasing interest in the past few years. To investigate ESD propagation and possible contributions from facilities, methodology, and analysis, we performed inverted gradient ESD tests of an International Space Station solar array coupon as part of a U.S.-wide Round-Robin test campaign. Geosynchronous earth orbit charging environments were simulated and current transients were simultaneously measured on ten solar array strings. In addition, images of ESD events were collected by low- and high-speed cameras, and an array of eight Langmuir probes positioned above the coupon was monitored. Preliminary results will be discussed, with special attention given to the effect of different analysis techniques on derived propagation velocity. Comparisons will be made with the results from other labs, and implications for spacecraft ESD events will be discussed.