X-Ray and VUV Spectra from the Laser Plasma Produced with “Kanal-2” Facility

Abstract

The paper presents experimental results obtained on “Kanal-2” facility. Laser radiation focusing on the surface of plane magnesium targets created the high temperature plasma, which emitted X-ray and vacuum ultraviolet (VUV) radiation. This radiation spectrum was investigated with two spectrographs: the mica crystal spectrograph (working range 8.2 ? - 9.6 ? ) and the grazing incidence VUV spectrograph (working rage 30 ? - 130 ? ). A set of beryllium stepwise attenuators appended the diagnostic complex and allowed us to get an approximated picture of a continuous spectrum within the range of 2.2 ? - 6.2 ? . The estimation of the plasma electron temperature T e from the ratio between the intensity of the dielectronic satellites and the resonance line gives T e ~ 180 eV. The ratio between the intensity of the resonance and intercombination lines gives the electron density of the emitting zone n e ~ 2 × 10 19 cm -3 . Some lines observed within the spectral range of 8.5 ? - 9.1 ? belong to none of the transitions of Mg ions. Perhaps the observed spectrum is determined by the transitions in so-called hollow ions of Mg, i.e. in the ions with unfilled inner shells. The spectra obtained with the grazing incidence spectrograph and with the minimum-directioned discrepancy iteration method of spectrum reconstruction from the attenuation curve in the beryllium stepwise attenuators are also presented.