Study of the possibility for increasing the emission of soft x-rays from the plasma of a low-energy vacuum discharge triggered by a laser

The spectral parameters of x-ray radiation in the wavelength range from 25 to 450 Å emitted by plasma of a vacuum discharge with a storage energy ≤45 J, induced on the Fe cathode by radiation from a neodymium laser with a power density up to 5 1012 W cm−2, are studied. On the basis of the collisional-radiative equilibrium model, a method was developed to produce a sufficiently accurate approximation of the experimental spectrum by a linear combination of the calculated spectra of plasma components with a given electron temperature and density. It was shown that the main part (>80%) of the radiation energy in the experimental spectra is provided by relatively cold peripheral plasma with a temperature of no more than 10 eV and a density of 5 1017 cm−3. It was established experimentally that a decrease in the laser power density due to the defocusing of the laser beam leads to an increase in the intensity of plasma radiation in the entire spectral range and a change in the spectral structure in the shortwave range. According to simulations, these changes are caused by an increase in the temperature and density of the micropinch formed in the discharge plasma up to 160 eV and 3 1021 cm−3, respectively.