Investigations on the motion of high-current vacuum arc cathode spots under magnetic field

A lot of research work has been done on the motion of low-current vacuum arc cathode spot. The relationship between cathode spot (CS) motion velocity, which contained magnitude and direction, and magnetic field was revealed, especially the relationship between direction of CS motion and the ratio of Bt/Bn. However, the motion of CSs in high-current vacuum arc has received less investigation. Thus we investigated the CSs motion of high-current vacuum arc in different axial magnetic field electrode by experiment. Experiments were conducted in a detachable vacuum chamber with arc current of 10kA (rms). Images of cathode spots were photographed by a high speed digital camera with an exposure time of 2 microseconds. With computer aided numerical processing, spatial distribution of cathode spots was obtained, based on which the magnitude and direction of CS motion velocity were calculated, and CS motion trajectory around current peak was plot. Results indicated that the properties of CSs motion in high-current vacuum arc were same to that in low-current vacuum arc.