Experimental Investigation on the Inf1uence of Axial Magnetic Field Distribution on Resisting the Constriction of a High-Current Vacuum Arc

<正> Effect of the axial magnetic field(AMF)on resisting the constriction of a highcurrentvacuum arc is studied in this paper.Two typical AMF distributions were investigated,i.e.,the traditional bell-shaped AMF,and the saddle-shaped AMF.Experiments were conductedin a detachable vacuum chamber with a rms arc current in the range of 10 kA to 25 kA.The arccolumn was photographed by a high-speed digital camera with an exposure time of 2 microseconds.The constriction of the vacuum arc was compared by processing the images of the arc column underthe two different field configurations and numerically determining the dimensions of the arc columnnear the electrodes.It was also confirmed that the AMF distribution had a significant influence onits effectiveness in resisting arc constriction.Furthermore,the AMF strength near the peripheryof the arc is more influential than that at the centre of the electrodes in resisting arc constriction.