Mars Axicell Radiation Damage and Shielding Analysis

Radiation effects and shield requirements are analyzed for the MARS axicell region. Dominant coil life limiting effects in the normal insert coils are found to be swelling in the spinel insulation and resistivity changes of the conductor due to transmutations. The shield between the insert and superconducting coils is optimized and reduces all radiation responses to acceptable levels. However, streaming in the neutral beam duct resulted in an unacceptable dpa rate in the Cu stabilizer and has resulted in a redesign of this region without a neutral beam and with a single insert coil.