Electron temperature and density measurements in laser-produced large-scale-length gas-bag plasmas by x-ray spectroscopy

Abstract

We present temporally and spatially resolved measurements of the K-shell emission from argon and chlorine dopants in laser-produced mm-size gas-bag plasmas. Particularly useful for the diagnostics of these plasmas are the line intensity ratios of the He- and H-like resonance lines to their respective Li- and He-like dielectronic satellite transitions. By Abel inverting the experimental spectra and applying time-dependent collisional-radiative modeling, local electron temperatures, and densities are deduced. About 0.4 ns after the beginning of the laser heating, we observe a homogeneous plasma center which heats steadily until the end of the heating pulse. Although the heating is slower than predicted by hydrodynamic simulations, the measured peak electron temperature of ${\mathrm{T}}_{\mathrm{e}}$=3 keV for neopentane-filled gas bags is in good agreement with the hydrodynamic simulations. In addition, the electron densities inferred from the line intensity ratio of the intercombination to the resonance line of heliumlike argon are consistent with ${10}^{21}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ as expected from the initial gas fill density. Further gas fill densities have been investigated, and in agreement with simulations we find lower temperatures for lower gas densities.