Change of the Tungsten neoclassical particle transport characteristic due to the coexisting of the lower- Z impurity in the tokamak plasmas

Abstract The high- Z impurity Tungsten neoclassical particle transport in the tokamak plasmas with the coexisting of the lower- Z impurity is investigated. The lower- Z impurity could reduce or enhance the Tungsten neoclassical particle transport. The Tungsten neoclassical transport characteristic will be changed with the lower- Z impurity content large enough. The dependence of the Tungsten neoclassical transport on the bulk ion radial gradients predicted by the existing impurity neoclassical transport theory will be broken. The existing impurity transport theory will over-predict (under-predict) the Tungsten neoclassical particle transport for the bulk ion radial gradients less (larger) than the critical value. The effect of the lower- Z impurity on the high- Z impurity neoclassical transport is through the parallel friction force coupling and it should be included in the Tungsten neoclassical particle transport calculation.