Bruce H. Failor

Interferometric measurement of physical phenomena during the implosion phase of a puff-on-puff Z-pinch load on Double-EAGLE

Theoretical studies have predicted that the disruptive role of the Rayleigh-Taylor (R-T) instability on the current conduction and implosion characteristics of annular Z-pinch loads will be mitigated by mass accretion if uniform fill or multiple annular shell loads are used. Holographic interferometry was used to study these physical processes during the implosion phase of puff-on-puff loads on a terawatt accelerator. Both axial (r-z) density perturbation and azimuthal (r-/spl theta/) filamentation modes of the R-T instability were observed. Significant ionization (Z/spl ap/3-10) of the inner gas puff atoms was observed below the anode grid before the outer puff had imploded to this radial position. Radiation hydrodynamic calculations indicate that photoionization by radiation from the outer current carrying shell could not account for this ionization. Current flowing on the inner gas puff could be the source of this ionization. The effect of these physical processes on the radiation yield from z-pinches warrants further investigation.

X-ray spectrograph for quick turnaround measurement of z-pinch plasma parameters

Our objective is to diagnose primarily Ar z-pinch plasmas with 1019<ne<1022 e/cm3 and 0.5<Te<2.0 keV at 0.2 mm spatial and 2 ns temporal resolutions. Our approach is to add Cl as a dopant, and use its He resonant to intercombination line ratio to estimate ne, and a He resonant to Li-like satellite line ratio to estimate Te. Ti is found from Doppler broadening. Because line brightness can be affected by high energy electrons in the tail of the distribution, we have measured the emission at polarizations both parallel and perpendicular to the applied electric field. We describe the spectrograph and the data obtained during experiments at the DECADE Module 2 facility at Maxwell Physics International.