  Space solar cell radiation hardness is of fundamental importance in view of
the future missions towards harsh radiation environment (like the Jupiter
missions) and for the new spacecraft using Electrical Propulsion. In this paper
we report the radiation data for triple junction (TJ) solar cells and related
component cells. Triple junction solar cells, InGaP top cells and GaAs middle
cells degrade after electron radiation as expected. With proton irradiation, a
high spread in the remaining factors was observed, especially for the TJ and Ge
bottom cells. Radiation results have been analyzed by means of the Displacement
Damage Dose method and DLTS spectroscopy. In particular with DLTS spectroscopy
it was possible to analyze the nature of a few defects introduced by
irradiation inside the GaAs sub cell observing a strong correlation with the
Displacement Damage Dose.
