Phenomena accompanying transient low-voltage discharges in liquid dielectrics. I ¿ Anode phenomena at low currents

ELECTRICAL spark-over between metallic electrodes in a liquid dielectric is followed by a high current-density discharge, the removal of electrode material, the formation of well-defined and characteristic electrode craters and, under some conditions, the production of colloidal suspensions of metal particles in the liquid. The associated phenomena have been the subject of many studies, originally with emphasis on colloidal suspensions,1,2 and more recently, in connection with ¿electrical¿ machining3,4 processes in which the electrode material removal is adapted for purposes analogous to those encountered in conventional machine tools. Despite the development of an extensive electrical machining art the physical phenomena involved have been incompletely understood. The authors have conducted several investigations of the physical phenomena, earlier results of which have been reported.3,4 Experimental techniques have subsequently been refined to achieve quantitative data which clarify both the process and its underlying theory. This paper is the first of a series on these results.