CHANGES IN TOKAMAK PLASMA PROPERTIES DURING IMPURITY INJECTION.

Certain applications of laser blow-off impurity injection, such as ion temperature measurement and spectral line identification, may require the ratio of injected ions-to-plasma electron density to exceed 0. 001. To achieve these concentrations, injection of micron-sized clusters as well as monatomic species has been relied on. In these cases the injected impurity can no longer be regarded as a nonperturbing trace sourced at the plasma edge. Therefore the variation of plasma parameters in PLT and PDX has been studied as a function of the amount of injected impurities, the species mix, and the type of impurity. The results are analyzed in terms of altered temperature profiles, impurity penetration profiles and impurity transport. These studies suggest criteria for performing nonperturbing transport experiments.