Optical investigations of vacuum arc development with different axial magnetic field contacts

By using a high speed CCD video technique, three different axial magneticfield contact systems i.e. unipolar, bipolar, and quadrupolar systems are investigated at an arc current of 10 kA effective. A low-current DC vacuum arc is initiated by contact separation before the high current is injected at a fixed contact distance of 10mm. Videos are taken from two directions perpendicular to each other in order to localize the vacuum arc properly. From these investigations, the transient development of vacuum arc under different axial magnetic field profiles can be visualized. The results are interpreted with respect to the behavior of the vacuum arc in the second half cycle after an eventual re-ignition.