The multicharged plasma implosion stability with respect to Rayleigh–Taylor axial modes and its modification by the electromagnetic field diffusion and radiation cooling is considered. The exterior and the interior parts of an imploded plasma shell are examined and stability and conditions for magnetohydrodynamic Rayleigh–Taylor instability are obtained. The external surface is always unstable. The interior instability appears, as a rule, to be under a significant degree of compression near the final stage of implosion. Theoretical results and numerical simulations using the two-dimensional ZETA code are [R. Benattar et al., 4th International Conference on Dense Z pinches, Vancouver (American Institute of Physics, Woodbury, 1997), p. 211] compared. The modeling of the implosion of wire arrays and nested tungsten wire arrays on the Z generator by the two-dimensional magnetohydrodynamic code ZETA, including radiation transport with local thermodynamic equilibrium (LTE)—nonequilibrium (non-LTE) approximation, is performed in order to study the influence of instability level on high-Z plasma radiation and to reproduce the experimental results. It is shown that it is possible to fit the experimental results if a 10% level of initial mass perturbation of the tungsten wire arrays is imposed. The dynamics of the implosion and the development of Rayleigh–Taylor instability are discussed. The plasma of the Z pinch is shown to be in a non-LTE regime.
radiography. Interior magnetic probes and auxilliary shots without working fluid injection were used to confirm that there is no magnetic field interior to the imploding Aluminum shell. Thus, diagnostic target compression, which was observed in worlung fluid compression experiments, was presumably due to the compressed hot hydrogen pressure. We obtained radiographs at 7 different times during the implosion discharge, from 3 shots with the same operating parameters. 3 of these radiographs were from the same shot. From these, it is possible to obtain average compressed working fluid pressure over time intervals observed by 3 radiographs. This data suggests that the compressed fluid pressure exceeds a megabar approximately 0.1 microseconds prior to contact of the imploding liner inner surface with the diagnostic target outer surface.'NumerEx, Albuquerque, NM Conventional Zpinches are known to be an effective source of soft X-rays [1,2]. However, this approach has limited control in redistributing the radiation spectrum, specifically toward the hard X-Ray regime where photon energies are >10 keV. The generation of such energetic photons requires both high densities and temperatures in the plasma. Due to the Rayleigh-Taylor instability and current (mass) limitations, these plasma conditions are difficult to achieve simultaneously. To produce a harder emitted X-ray spectrum, the "Liner-Converter" scheme was proposed at the Kurchatov Institute [3]. This technique uses the thermal flux from the end of a low-Z pinch to rapidly heat a thin, high-Z converter linked to the edge of the pinch. A temperature of 10 keV can be achieved in the converter by fast and efficient heat transfer from the low Z-pinch liner; this results from the strong dependence of thermal flux on electron temperature. Using a low-Z pinch liner minimizes radiation losses and instability growth, while maximizing end-losses to the converter. By employing a separate converter, there is flexibility in choice of materials and radiator geometry.The mTA-code is developed for the complete simulation of 2-D multicharged ion plasma magnetohydrodynamics and radiation. The code consists of three main parts: preprocessor, core processor, and postprocessor.The code ZRMHD is a core processor of the ZETAcode. It is designed to perform simulations of 2-D axially symmetrical magnetohydrodynamic flows of radiative plasma. The module AERG is introduced into ZRMHD for multigroup radiation transport calculations in the semi-analytical self consistent model. The ZRMHD uses as a rule tables for EOS, opacities, emissivities and plasma electron transport coefficients prepared by THERMOS pre-processor of the ZETA-code.The ZRMHD involves mathematical model, physical model and control visual system. The mathematical model is based on implicit Newton-type iterative algorithms in the fully conservative difference scheme, in Euler-Lagange variables with automatic values recalculation to the grid changed and algorithms of a grid reconstruction. The energy balance calculation is carried ...
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