Diagnostics of the Cathode Sheath Expansion After Current Zero in a Vacuum Circuit Breaker

Langmuir probes operating in the electron saturation current mode were used to detect the time of the arrival of the cathode sheath at the probe position. The probe current was measured just before and after current zero (CZ) followed the transient recovery voltage in a gap with copper electrodes. Probe measurements were accompanied with the detection of the postarc currents. Basic plasma parameters such as electron temperature and density were measured in the vicinity of the arcing gap. The data set allowed us to reconstruct the sheath dynamics after CZ.