Plasma-cathode interaction in superdense glow discharges

Summary form only given. Two stable solutions are shown to exist which can explain the high power flux at the cathode surface necessary to achieve thermionic emission associated with superdense glow discharges. The first is a `really´ homogeneous current density distribution with ion current density on the order of several kiloamperes per square centimeter. This requires a comparably large electric field inside the bulk plasma on the order of 100 V/cm. A calculation of the electrical conductivity of the plasma supports the assumption of such a high internal electric field. The second solution is a current density distribution which is homogeneous at the plasma sheath edge but is constricted at the cathode surface to form multiple cathode spots simultaneously. An estimation of the space-charge limitation of electron flow, surface heating, and thermionic emission, in comparison to experimentally observed cathode erosion rates, indicates a stable solution at an electron current density of the order of 10⁵ A/cm² for molybdenum electrodes, and a cathode spot temperature around 4600 K