EUV Spectroscopy of Low-Temperature Plasmas Created in the Final Anode-Cathode Gap of the Z-Machine

Summary form only given. The effect of a short-circuit across the final anode-cathode gap of the powerful Z-Accelerator could hamper effective power delivery-to the Z-pinch plasma. The objective of this work is to develop EUV spectroscopy methods for electron temperature T_e measurements in plasmas created in the final transmission line (A-K gap near the load) of the Z-Accelerator (Z-Machine) at the Sandia National Laboratories (SNL). The methods are based on theoretical calculations and experimental investigation of EUV spectra of highly charged Fe ions in well diagnosed laser-produced plasmas, and comparison of these spectra with the EUV spectra observed in the A-K gap plasmas. Experimental EUV techniques include modified special EUV grazing incidence spectrometers for the spectral range of 2-80 nm and developing techniques to protect the instruments from damage from shock wave, explosion products, and radiation from the z-pinch load. Experiments at SNL have shown that the most stripped ion observed in the spectra is FeXVI-FeXVII. The electron temperature T_e is estimated from the observed spectral distribution (lambda_max) in a spectral range of lambda~50-70 Aring and from the observed maximal ionization level (FeXVII). Comparisons of both the theoretical data and laser-produced plasma experimental data with the Z-Machine spectra give a T_e value of ~200 eV in the A-K gap plasmas.