PULSED ELECTRICAL BREAKDOWN IN LIQUID-HELIUM IN THE MU-S RANGE

Information about breakdown time lags under pulsed voltage stress is p rerequisite to the insulation design of superconducting devices. Exper iments have been carried out using a pulse generator which provides a step voltage with 200 ns rise time and a long decay time constant of m ore than 1 ms. The present experiments may bridge the information gap between time lag measurements in the ns range using extremely high fie ld strengths, and existing data found with usual lightning impulse vol tage. The test device is described in the paper, and some typical resu lts are discussed in detail.