EFFECT OF EPOXY CRACKING RESISTANCE ON THE STABILITY OF IMPREGNATED SUPERCONDUCTING SOLENOIDS

The stability and quench positions of superconducting test solenoids i mpregnated with three types of epoxy resin, with different crack resis tances, have been studied. Voltage signals and acoustic emission (AE) were monitored during training tests. Premature quenches in the soleno ids almost occurred at the innermost layer of windings; voltage spikes and AE appeared just prior to the premature quench initiation. This s uggested that premature quenches were due to friction or debonding bet ween ground insulation and winding. The solenoid with a release film b etween ground insulation and winding showed high stability and reached critical current at the second charging. From the results, the effect s of epoxy cracking resistance on the stability of impregnated superco nducting test solenoids are discussed.