Effect of plasma shaping and resonance location on minority ion temperature anisotropy in tokamak plasmas heated with ICRH

Artikel i vetenskaplig tidskrift, 2012

Poloidal asymmetries of the impurity distribution, which are observed in tokamaks, may influence the impurity cross-field transport. Low field side ion cyclotron resonance heating (ICRH) often results in an inboard accumulation of impurities, which may in turn lead to an outward convective impurity flux. The temperature anisotropy of the ICRH-heated minority ions is identified to be one of the main parameters governing the impurity asymmetry strength. In the present work we analyze the effect of plasma shaping and the ICRH resonance location on the minority temperature anisotropy by means of the TORIC-SSFPQL modelling. We find that ellipticity reduces the anisotropy level due to the wave defocussing and broader absorption regions for the elongated plasmas. The temperature anisotropy decrease in case of the resonance layers located closer to the edge is caused by the significant reduction in heating power densities due to geometrical reasons.