Total impurity radiation power losses from steady-state tokamak plasmas

Abstract

A one-dimensional hydroclynamic-coronal model has been used to calculate the total radiated power loss, Prad from a steady-state tokamak plasma. The results are expressed in terms of quantities routinely measured in most experiments so that scaling with different plasma parameters can readily be seen. Prad is strongly dependent on electron density and temperature in coronal equilibrium (i.e. Prad ∼ with δ ≅ 2.0 and γ between 0.5 and 1.5). The strong anomalous diffusion in many plasmas can, however, considerably reduce these dependences (δ as low as 0.8 and γ between −0.1 and 0.9). Prad can be less than the coronal equilibrium value, but usually it is larger by as much as two orders of magnitude, depending on the diffusion coefficient. A criterion has been developed for the applicability of coronal equilibrium to calculate Prad. Also, expression of the calculations in a simplified form has indicated an accuracy of about a factor of two when applied to more than a hundred experimental plasmas. These results show Prad is often a dominant loss mechanism and can, therefore, lead to considerable modification of existing scaling laws.