Fast-discharge excitation of hot capillary plasmas for soft-x-ray amplifiers

Abstract

High-temperature (${\mathit{T}}_{\mathit{e}}$>150 eV), small-diameter (\ensuremath{\sim}200 \ensuremath{\mu}m) plasma columns have been efficiently generated by very fast (13 ns rise time, 28 ns full width at half maximum) pulsed discharge excitation of capillary channels filled with preionized gas. Discharges in argon-filled capillaries at currents between 20 and 60 kA produced plasmas with Ar x--AR xiv line emission, in which the degree of ionization was controlled by the magnitude of the current pulse. The characteristics of these plasmas differ from those created by vacuum discharges in the same capillaries and approach those necessary for soft-x-ray amplification in low-Z elements.