Vacuum Pressure Impregnation Process in Superconducting Coils: Best Practice

The technology associated with the design and construction of superconducting magnets has evolved dramatically over the last three decades leading to an overall increase in their complexity. Their use has moved from particle physics through medical applications such as MRI to the very large magnets demanded by fusion technology, where the optimal quality of the HV insulation is a critical step in achieving the design performance. The Vacuum Pressure Impregnation (VPI) technique—a particularly refined case of the more widely known Vacuum Assisted Resin Transfer Mould (VARTM)—has become the most common process for the consolidating electrical insulation of large superconducting magnets. To achieve success with the VPI process demands that detailed attention is paid to many steps, namely: coil drying, resin degassing and coil impregnation.