X Radiation from Optical and Inner-Shell Transitions in a Highly Ionized Dense Plasma

Abstract

X-ray line emission originating from "optical" (dipole and intercombination) transitions in heliumlike copper, iron, and titanium and hydrogenic iron and titanium ions has been observed in a concentrated dense plasma formed in a linear low-pressure discharge. In addition, emission from inner-shell x-ray transitions in Fe XIX-XXIV and Ti XV-XX ions has been identified. The measured wavelengths are compared with theoretical predictions and other observations. Continuum emission at wavelengths shorter than the Lyman-series limit for hydrogenic species has been used for electron temperature and density determination and as evidence supporting a thermal-electron collisional ionization model. Plasma dynamics studies indicate the existence of an axially propagating radial pinch, collapsing near the anode to a minute point.