Measurement of arc velocity in an arc-rotating pulsed power switch based on B-dot probes

The B-dot probes are installed in an arc-rotating pulsed power switch to measure the arc velocity. Six B-dot probes are set symmetric in a circle under the gap to obtain the arc velocity variation of current. The probe signal is calculated in a simplified theory and the result is compared with the experimental waveform. The difference between them attribute to that the arc shape is complex and varying continuously during rotation. The zero-crossing point of measured voltage signal is not correspond to the moment when the arc is just above the probe. The velocity in every 1/3 circle was calculated in order to reduce the error. The arc rotates at about 550 m/s in current of 20 kA, and the velocity variation is obtained from the probe voltage signals.