Soft x-ray emission from a pulsed gas discharge in a pseudosparklike electrode geometry

Abstract

The mechanism of the soft x-ray generation in a pulsed high current discharge is investigated by means of time and space resolved characterization of the extreme ultraviolet emitting regions and discussion of the related electrical circuit parameters. The plasma is ignited in a pseudosparklike electrode geometry. In a discharge of 15 J, stored electrical energy characteristic emission of different gases (oxygen, argon, and nitrogen) is excited in the spectral range from 2 to 5 nm. Special interest is devoted to the 2.88 nm line emission of heliumlike nitrogen ions within the spectral range of the water window to be used for x-ray microscopy. For the nitrogen discharge, an admixture of xenon leads to axial shorter plasma emission as well as to a smaller diameter below 300 μm of the short wavelength emission. Investigation of the xenon related emission in the range of 10–16 nm indicates that radiative cooling is a possible reason for the observed decrease in the radius. Time and spatial resolved images show that the x-ray emission exhibits an axial dynamic in addition to the usual compression occurring in pinch plasmas.