Experimental Characterization of Plasma Expansion on Solar Arrays and Comparison With Numerical Simulations of Flashover

This article presents the measurements of electrostatic discharge (ESD) properties on solar arrays and comparisons with results from solar cell charging and electrostatic risk/flashover bubble simulator (SoCCER/FOEBUS) numerical simulation code, which couples a cathode spot model and a plasma expansion model. Several configurations of solar array simulants have been tested to determine the influence of key parameters such as the panel dimensions and the electrode material on the flashover current and the plasma expansion dynamics along the dielectric surface. Electrical measurements of global and local neutralization currents are used to determine ESD duration, flashover charge, and neutralization radius. In parallel, a microwave resonant probe (curling probe) has been used to measure the electron density at various distances from the ESD site and to determine the expansion velocity of the plasma bubble. A good agreement is globally found between experimental results and numerical simulations; the same trends are obtained concerning the influence of the key parameters, and flashover characteristics (duration and charge) are very similar for the largest <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$120\times 120$</tex-math> </inline-formula> cm array. The electron temperature and the initial plasma density in the cathode spot inferred from curling probe measurements are in line with predictions of the cathode spot model. These results present a global validation of SoCCER/FOEBUS code for the simulation of flashover on solar arrays and offer the possibility to use it for the evaluation of extreme ESDs on large solar arrays considering a worst case scenario.