Study on Secondary Arcing Occurrence on Solar Panel Backside Wires With Cracks

Space environment exposure may create cracks on solar panel backside wires. In terms of the wiring design of the solar array backside, environmental constraints applied on each wire are identical. Thus, the probability of two adjacent wires having cracks facing each other is very high. This configuration presents a risk of secondary arc occurrence, which can lead to a destructive process such as arc tracking. In order to determine in which conditions electrostatic discharges (ESDs) can lead to an arc, we have carried out an experimental study on solar panel backside-like samples. We have tested different types of wires presenting artificial mechanical cracks or space simulation aging cracks, set on a solar panel backside coupon. The wires are connected to a secondary arc test setup including a solar array simulator (SAS) set to different current values. As both direct and inverted potential gradient (IPG) charging are theoretically possible on geostationary orbit and low earth orbit, we have carried out, in the JONAS vacuum chamber (ONERA facility), both charging types. Direct charging was achieved with an electron gun and IPG with a plasma source. Results are presented for the two types of charging, different types of wires, and different SAS current values. They show that, in direct charging conditions, ESD propagates along the wires but the plasma density is too weak to provoke an arc. In IPG situation, ESDs are able to trigger different arc types, such as nonsustain arc, temporary sustain arc, and permanent sustain arc, depending on SAS current values.