EUV spectroscopy of low-temperature plasmas created in the final anode-cathode GAP of the Z-machine

The effect of a short circuit across the final anode-cathode (A-K) gap of the powerful Z-Accelerator could hamper effective power delivery to z-pinch plasmas. The objective of this work is to develop an extreme ultraviolet (EUV) diagnostic technique for diagnosis of the low-temperature plasmas created in the final transmission line (A-K gap near the load) of the Z-Accelerator at the Sandia National Laboratories (SNL). The purpose of this effort is to help in understanding and mitigating this potentially serious problem. This work includes developing EUV grazing incidence spectrometers, investigation of the EUV spectra of highly charged ions in well diagnosed laser-produced plasmas, and the comparison of these laser plasma spectra with the spectra of plasmas created in the inner transmission line. Spectra of highly-charged iron (Fe) ions were investigated using EUV spectroscopy methods in a spectral range of 2 to 80 nm. Experiments at SNL have shown that the most stripped ion observed in the spectra is FeXVII. Comparison of the experimental spectra of FeIII through FeXVII ions with theoretical calculations gives an electron temperature Te of ∼ 200 eV.