About the effect of gamma radiation on the dielectric properties of the insulation of wires used in superconductive magnets for particle accelerators

This study investigates radiation induced electrical degradation in superconducting and instrumentation and control (I&C) wire insulations for particle accelerators through dielectric spectroscopy, DC insulation resistance, breakdown voltage, and FTIR analysis. Two different electrical insulation systems, namely polyvinyl alcohol (PVA) and polyimide (PI) and their degradation with radio-chemical aging are investigated. PVA shows clear chemical modification, confirmed by the growth of carbonyl, hydroxyl, and methyl FTIR bands. This resulted into enhanced dipolar relaxation, dielectric losses, DC conductivity, and moderate reduction of breakdown voltage. In contrast, PI undergoes negligible chemical change; its dielectric evolution is instead linked to physical aging and defect formation within the multilayered architecture of the wire. This leads to increased interfacial polarization and reduced dielectric voltage. The identified structure-property relationships demonstrate the effectiveness of electrical tests as nondestructive tools for aging evaluation in radiation harsh environments.