X-ray emission spectrum of a magnesium plasma heated by picosecond ruby laser pulses

An investigation was made of the x-ray emission spectrum of a magnesium plasma heated by ruby laser pulses of 10–20 psec duration and $10^{14}$ W/cm$^2$ power density on the target surface. The relative intensities of the spectral lines were used to determine the electron temperature (200 eV), density $[(1-1.15)\times10^{20}$ cm$^{-3}]$, and ionization state ([Li]/[He]$\approx$1) of the luminous part of the plasma. The relative intensities of the resonance lines of the H- and He-like ions yielded an estimate of the electron temperature in the vicinity of the critical point ($T_{\text{cr}}\gtrsim550-700$ keV).