"Point" X-ray source engendered by hot spots in a high-current discharge

Summary form only given, as follows. The hot spots occurred in high-Z plasma of high-current vacuum discharges observed to be the bright sources of EUV and X-rays. The thorough study of discharge dynamics and radiation performance of a vacuum spark was carried out previously. The experimental model of industrial EUV/X-ray source was designed and tested and its application for X-ray lithography and X-ray microscopy was examined. The experiments showed that the hot spot is a local high-density, high-temperature plasmoid caused by the "neck" development on the discharge plasma column and subsequent compression of the neck pinch, apparently, because of the radiation losses from the compressing plasma. Eventually, one or several high-density "micropinches" are generated in the neck emitting a burst of soft X-ray radiation produced by the highly ionized atoms mostly in the form of line radiation. The micropinch (hot spot) size displayed by radiation near 1 keV is approximately 40/spl times/150 micrometers; usually it decays into several spots recorded in radiation above 4 keV. The X-ray output from a separate micropinch was evaluated /spl sim/10/sup -15/ W/sr cm/sup -3/ for a spectral band 0.5-1.5 keV. The details of neck evolution are discussed and the limiting conditions for micropinch occurrence are outlined. The experimental data are compared with the computer simulation of high-Z plasma pinch compression allowing for radiative losses.