Potential distribution in magnetic arc discharges

Summary Using a new hot probe technique, valuable information has been gathered about the potential distribution of the central arc column of a discharge with an axial magnetic field. Deep potential troughs have been found in case of electro-negative gases (O₂, Cl₂). In the oscillating electron type of discharge the troughs are much deeper, e.g. 90 V in case of an arc voltage of 100 V. The central plasma potentials for electro-positive gases (A, H₂, N₂) are still negative in comparison with the anode potential, which is in striking contrast with earlier investigations. The depth of the potential troughs has been investigated as a function of current, pressure and gas composition.Much of this work was done together with Drs. J. Snieder. The investigation is part of the research program of the Stichting Fundamenteel Onderzoek der Materie and is made possible by financial support from the Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek.