Impurity effects on quasi-linear particle transport induced by ubiquitous modes in tokamak plasmas

The impurity effects on quasi-linear turbulent transport induced by ubiquitous modes (UMs) and typical trapped electron modes (ty-TEMs) in tokamak plasmas are numerically investigated and identified, employing a full gyrokinetic description for main and impurity ions. The overall characterization of TEMs is demonstrated to be categorized into typical TEM (propagation in the electron diamagnetic drift direction ) and UM (propagation in the ion diamagnetic drift direction ). The behaviors of both instabilities and induced particle transports in the presence of impurity ions are studied in the broad parameter regions, containing the effects of concentration, density gradients, charge and mass numbers of impurity ions, temperature gradients as well as temperature ratio. The results indicate that the ty-TEM and UM instability and induced particle flux of main ion and electron exhibit distinct responses to the impurity density gradients, particularly for the case of negative . Moreover, large ion and electron temperature gradients, high electron-to-impurity temperature ratios, and heavier impurities with higher charge numbers significantly enhance the stabilizing effect on UMs and more effectively reduce the particle flux. Significantly, the inward particle fluxes of both electrons and main ions and outward impurity fluxes can be observed in a sufficiently high range, such as , where UMs dominate. The above benefits for the formation and maintenance of particle pinch and the mitigation of impurity ion accumulation.