Effective versus ion thermal temperatures in the Weizmann Ne Z-pinch: Modeling and stagnation physics

• Published in: Physics of plasmas 2014-03, Vol.21 (3)
• Main Authors: Giuliani, J. L., Thornhill, J. W., Kroupp, E., Osin, D., Maron, Y., Dasgupta, A., Apruzese, J. P., Velikovich, A. L., Chong, Y. K., Starobinets, A., Fisher, V., Zarnitsky, Yu, Bernshtam, V., Fisher, A., Mehlhorn, T. A., Deeney, C.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APPROXIMATIONS; BREAKDOWN; Computational fluid dynamics; Computer simulation; ELECTRON DENSITY; ELECTRONS; EMISSION; Fluid flow; Gas puff Z pinch plasmas; IMPLOSIONS; ION TEMPERATURE; K SHELL; LINE WIDTHS; Magnetohydrodynamics; Mathematical models; Modelling; Neon; PASCHEN LAW; PEAKS; PLASMA; Plasma physics; RADIAL VELOCITY; SIMULATION; SPECTROSCOPY; STAGNATION; Temperature; Velocity gradient
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.4865223

The difference between the ion thermal and effective temperatures is investigated through simulations of the Ne gas puff z-pinch reported by Kroupp et al. [Phys. Rev. Lett. 107, 105001 (2011)]. Calculations are performed using a 2D, radiation-magnetohydrodynamic code with Tabular Collisional-Radiative Equilibrium, namely Mach2-TCRE [Thornhill et al., Phys. Plasmas 8, 3480 (2001)]. The extensive data set of imaging and K-shell spectroscopy from the experiments provides a challenging validation test for z-pinch simulations. Synthetic visible images of the implosion phase match the observed large scale structure if the breakdown occurs at the density corresponding to the Paschen minimum. At the beginning of stagnation (−4 ns), computed plasma conditions change rapidly showing a rising electron density and a peak in the ion thermal temperature of ∼1.8 keV. This is larger than the ion thermal temperature (