Temporal evolution of micro-plasma in a repetitive vacuum arc soft x-ray source

Abstract

Soft x-ray emission from a short vacuum gap, operated with a repetitive low-current discharge was investigated. Electrons are accelerated by an electric field in a cathode sheath that is formed after arc extinction, and soft x-rays were emitted in the period between arc extinction and subsequent breakdown. The schlieren photographs and Langmuir probe diagnostics showed that the micro plasma of diameter less than 1 mm is formed during arc phase, and the ion sheath extended with velocity of 104/m/s , which agreed with calculation. The existence time of the dense plasma was 10 - 20 ns.