Impurity effect on kinetic ηi‐mode in tokamak plasma

The impurity effects on the ion temperature gradient driven mode, or ηi‐mode, in a tokamak plasma are studied in shearless slab, sheared slab and toroidal magnetic confinement configurations. The stability analysis shows that the impurity ions have a stabilizing effect on the mode in high temperature tokamak plasmas and such effects depend on (i) the impurity concentration in the plasma (the dilution effect), (ii) the density profile of the impurity ions (when Tz=Ti is assumed with Ti and Tz being the temperature of the hydrogen and impurity ions, respectively), (iii) the dynamics of the impurity ions. The analysis also shows the importance of taking impurity parameters into account when experimental results are analyzed with ηi‐mode theory. In the limit of adiabatic electron dynamics the ambipolar of the total particle flux is achieved by the balance of the outward working gas (hydrogenic) particle flux with the inward impurity flux.