Perpendicular propagation velocity of a Townsend discharge in crossed DC uniform electric and magnetic fields

Abstract

By using a pulsed ultraviolet light source, the propagation velocity, in the range 0.19-8.15 x 10 4 m s -1 , of a Townsend discharge has been measured oscilloscopically as it travels perpendicularly to the applied crossed DC uniform electric and magnetic field in ethane gas near the Paschen minimum along ski-shaped electrodes having suitably placed monitoring probes in the cathode. Fundamental measurements of the electron avalanche deflection angle and the positive ion drift velocity allow the calculated continuous and stepped propagation velocity to be compared with the measured one, by using an earlier simplified model and a more developed one; agreement is good. This opens up new areas for study of Townsend discharges and a successful correlation with magnetic arc movement is reported.