This report was prepared as an account of work sponsored by the United States Gavernment. Neither the United States nor the United States Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or asdumes any legal liability ar responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or procesis disclosed, or represents that its use would not infringe privately amed rights.
The impurity radiation for typical tokamak parameters has been numerically calculated using an “average-ion model”. Coronal equilibrium values for the emission of oxygen, iron, molybdenum, tungsten and gold were determined from the steady-state solutions of a set of related rate equations which included the effects of electron collisional ionization and excitation, dielectronic and radiative recombination, Δn = 0 and Δn ≠ 0 line transitions, and bremsstrahlung. The results for oxygen, iron, and molybdenum compare very well with other calculations. Since impurities diffusing in a tokamak are not expected to be in coronal equilibrium, time-dependent radiation calculations were also performed. A comparison of these non-equilibrium loss rates with those calculated under the assumption of coronal equilibrium indicates that coronal radiation calculations do not significantly underestimate the moderate- and high-Z impurity radiation losses for neoclassical diffusion velocities in large tokamaks, such as Princeton Large Torus and Tokamak Fusion Test Reactor. Finally, the detailed steady-state emission rates were used to investigate the effects of various concentrations of impurities on the neτ requirements for breakeven, ignition, and Q = 5 beam-driven reactor experiments.
This report was prepared as an account of work sponsored by the United States Gavernment. Neither the United States nor the United States Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or asdumes any legal liability ar responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or procesis disclosed, or represents that its use would not infringe privately amed rights.
This report describes the non-LTE atomic-state computer program, XSNQ-U. The original classified report was issued in 1971 (Ref. 1). Since then, impor tant changes and improvements have been included. XSNQ-U provides frequency-dependent emission and absorption coefficients 2 for a material not ii LTE (local thermodynamic equilibrium). As in XSNB, an LTE opacity subroutine, a compromise has been sought between accuracy and com puter speed. The result, XSNQ-U, is intended for use as a subroutine in any transport code. This report surveys the basic non-LTE equations for the 3 4 average ion model, as pioneered by Grasberger, ' and gives details for the approximations and technique used in XSNQ-U. Also included are some illustrative numerical examples. Since the writing of the classified report, the code has been modified by W. H. Grasberger and J. E. Ramus to handle the case of multiple elements. The extension is straight forward and would only make the notation more cumbersome if the single-element notation of this report were replaced by the multipleelement notation. Also, the method of solving the rate equations by using analytical differentials as discussed in the classified report has been replaced by a more direct incremental differences scheme, which is discussed in the present version. where N is che number density of particles in state n.
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