Initiation and Sustainment of Unipolar Arc Discharges by a Microsecond Pulse Plasma

Unipolar arcs have been produced by contacting metal surfaces with microsecond pulse plasmas. Plasma temperature T_e, density n_e and potential (with respect to ground) were controlled in the limits 7–12 eV, 10¹⁸–10¹⁹ m^?3, 20–40 V, respectively, and the influence of these parameters on arc current amplitude (50–500 A) and ignition probability has been investigated. It was found that the ignition is the most limiting process requiring surface contaminations as well as the transport of net currents to the surface. The amplitude of the current was proportional to n_eT_e^1/2.