Magnetically driven high current switching arcs in vacuum and low pressuregas

The behavior of high current switching arcs in transverse magnetic fields i s essential for the design of switching elements, in which are motion is us ed to reduce contact erosion. In this paper magnetically driven arcs in vac uum and low pressure gases are investigated at currents of several tens of kA, Arcs driven in a low pressure environment exhibit a peak are velocity o f more than 1 x 10(5) m/s, exceeding those of comparable vacuum arcs by at least two orders of magnitude. The influences of current amplitude, gas pre ssure, and the kind of gas filling on the are velocity are investigated. A threshold behavior concerning the minimum requirements for a nonstationary are is found. An improved model is presented, which explains the observed p eak are velocities in vacuum and in low pressure gases.