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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.

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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.

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