Innovative technologies on proton irradiation ground tests for space solar cells

Imaizumi, Mitsuru*; Yuri, Yosuke; Bolton, P.; Sato, Shinichiro; Oshima, Takeshi

High-energy proton irradiation tests were performed on InGaP/GaAs/Ge triple-junction (3J) solar cells with a variety of beam conditions. Irradiation area of about 80 mm 80 mm was achieved by two different techniques, namely, the spot beam scanning and the defocused beam uniformization using multi-pole magnets. Degradation trend of the cells irradiated with the defocused uniform beam under a variety of doze rates exhibited no significant difference compared to the trend irradiated with the scanned beam under a constant dose rate. This result is consistent with our previous fundamental study, and indicates possibility of reduction of irradiation test duration. Irradiation experiment with a multiple energy proton beam is planned, and generation of such proton beam is now under development. Once a proton beam with energy spectrum similar to space environment, a number of irradiation tests with different proton energies and also an energy equivalent fluence calculation using relative damage coefficients or displacement damage dose will be unnecessary.