An efficient tabulated collisional radiative equilibrium radiation transport model suitable for multidimensional hydrodynamics calculations

A computationally efficient method for transporting radiation in multidimen sional plasmas has been developed and evaluated. The basis of this method i s a uniform plasma approximation that allows one to utilize existing escape probability techniques that are successfully used in one-dimensional (1D) calculations to approximately solve the multidimensional radiation transpor t problem. This method is superior to diffusion methods because (1) the pro bability of escape technique insures that the plasma goes to the correct op tically thin and thick limits, (2) the effects of line absorption due to ph otoexcitations are modeled, and (3) this method uses source functions that are based on a self-consistent nonlocal thermodynamic equilibrium calculati on, not an ad hoc assumption that the source functions are Planckian. This method is highly efficient because equation of state information from 1D ca lculations is tabulated as a function of plasma internal energy, ion densit y, and the line probability of escape from a uniform plasma, and then used in multidimensional calculations. Given the internal energy and ion density , and by calculating the line probability of escape from a zone of the mult idimensional plasma, the equation of state, including emissivities and abso rption coefficients, of the zone is determined from the table. Total radiat ive power, K-shell radiative power, total radiative yield, K-shell radiativ e yield, and plasma density and temperature profiles obtained from 1D Z-pin ch calculations employing this method are in good agreement with the same p owers, yields, and profiles calculated using a full radiation transport mod el. This method has been implemented in the 2D plasma radiating imploding s ource model code [F. L. Cochran , Phys. Plasmas 2, 2765 (1995)] to determin e the influence of radiation transport in argon Z-pinch experiments perform ed on the Z machine [R. B. Spielman , Phys. Plasmas 5, 2105 (1998)] at Sand ia National Laboratories. (C) 2001 American Institute of Physics.