Theoretical and experimental investigations of the suitability of low-current Z-pinch plasma as an absorption medium for laser radiation

In this study the electron density of Z-pinch plasmas driven at relatively low currents (ca. 2-5 kA) was determined using only emission spectroscopy. The suitability of a hollow-cathode-triggered z-pinch plasma as an absorption medium for laser radiation was investigated. The temporal and spatial behaviors of electron temperature and density profiles were estimated using magnetohydrodynamic (MHD) simulations to evaluate the experimental results. Temperature measurements were performed according to the Boltzmann plot method in the visible spectrum range, using the fact that, in low-current Z-pinch plasma, a local thermodynamic equilibrium prevails for states at high principal quantum numbers (partial local thermodynamic equilibrium). In this case, the Saha equation can be used to determine the electron density. The results demonstrate that this method of determining the electron temperature and density of z-pinch plasmas is only applicable during the pinching phase. However, in this case the experimentally determined values are in fairly good agreement with the values determined using the MHD model. A user-oriented 1-D radiation MHD code was used to simulate the dynamic evolution of the plasma. The experimentally determined maximum electron temperature of approximately 12 eV is in fairly good agreement with the simulated value. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)