Particle-induced degradation of III-V multi-junction solar cells under different configurations of displacement damage dose

The solar arrays of spacecrafts are subjected to a severe radiative environment. Associated degradation rates are dependent on operational orbit configuration. The current approach used in models and tools to determine power degradation shall thus be validated to ensure good prediction accuracy. This paper reports on extensive irradiation test campaigns realized on triple-junction solar cells to compare degradation induced by different configurations of irradiation reproducing nominally the same displacement damage dose (DDD) in the active layer. These test campaigns data are used to support the validation of a new tool developed to optimize prediction accuracy of solar cell degradation. The DDD equivalence between front/rear irradiation on solar cell assemblies and on bare solar cells, between different electron and proton energies, as well as the verification of the superposition principle are addressed. Results are conclusive regarding the equivalence of degradation obtained with electrons, protons and/or combined electrons and protons, accounting for local shielding.