Plasma points and radiative collapse in vacuum sparks

Abstract

This review discusses the intense x-ray emitting regions, called plasma points, that appear in low-inductance vacuum sparks and other high-current discharges. Accurate x-ray spectroscopy indicates the existence of two types of plasma points with different plasma parameters. One type is extremely small (∼microns), dense (∼1023/cm3), and hot (≳1 keV), while the second type is an order of magnitude less extreme. A dynamic model (Vikhrev 1982a) based on radiation cooling with axial outflow of plasma predicts a radiative collapse that is consistent with many features of the plasma points.