ABSTRACT
Solar cells are known as some of the most important components for spacecraft since they produce the electric power needed for operation. The output performance of solar cells degrades in space due to damage induced by highly energetic particles such as electrons and protons. Therefore, we must know the radiation response of solar cells and predict their degradation behaviour in orbit before spacecraft are launched. For this purpose, ground-based irradiation testing for space solar cells is being conducted using particle accelerators. However, since conventional accelerators are used for the ground-based testing, solar cells must be irradiated individually with electrons and protons at any given single energy; although protons and electrons in space have known energy distributions. State-of-the-art space solar cells especially have a multi-junction structure, in which three or more component subcells made of different materials are stacked into a solar cell. As a result, the degradation behaviour of multi-junction solar cells is not simple, and ground-based testing using electrons and protons in small energy steps should be done to clarify degradation of multi-junction solar cells in the actual space radiation environment. Laser-driven ion/electron beams with broad energy spectra can solve this issue. In Chapter 15, radiation effects in space solar cells and their lifetime prediction methods are described. The usefulness of laser-driven ion/electron beams for irradiation testing for space solar cells and the prospects for laser-driven beams are discussed.
