Analysis of solar-cell array panel (SAP) data from the Arase satellite orbiting\nin the inner magnetosphere showed a clear degradation of solar cells that\ncould be attributed to trapped protons with energies greater than 6 MeV.\nProton fluence was determined based on variations in the open-circuit voltage\n(Voc) of the solar cells, which we compared with that expected based on\nvarious distribution models (AP8MAX, AP9 mean and CRRESPRO quiet) of\ntrapped protons. We found a general agreement, confirming the major contribution\nof trapped protons to the degradation, as well as a slight difference\nin the fluence expected based on the model calculations. To minimize this\ndifference, we slightly modified the models, and found that concentrating the\nenergetic protons on the magnetic equator provided a better agreement. Our\nresults indicate that >6 MeV protons also has the equatorial concentration as\nreported for >18 MeV protons from the Van Allen Probes observation, and\nare interpreted as two components of the trapped protons, i.e. , those of solar\nenergetic particle (SEP) origin have an anisotropic pitch-angle distribution\nand are confined near the magnetic equator
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