Quench Heater Technology for HL-LHC Superconducting Accelerator Magnets

Quench heaters for the active protection of superconducting magnets are large flexible circuits that are produced in a photolithographic process. The HL-LHC quench heater base material, the circuit production process and the qualification tests are described. For potential future use as interlayer quench heater, a Cu coating with a Ta diffusion barrier has been developed that can resist the high temperatures needed for coil reaction. The application of a coverlay enables dielectric tests at voltages that approach the specified breakdown strength of the polyimide insulation. Potential further improvements of heater performance and robustness are discussed.