The Influence of ICRH-driven Energetic Ions on the Stability fo Optimised Shear Discharges in JET

摘要

The optimised shear scenarios being developed at JET during the 1998-1999 experimental campaign requie the use of high power auxiliary heating in low-density target plasmas. under these ocnditios, Ion Cyclotron Resonant minority Heating with P_ICRH>6 MW Alfven Eigenmodes in thefrequency range of 100-200 kHz, fishbone-like modes [1] in the frequency range of 20-40KHz, higher frquency chirping modes, nad can influence the stability of the pressure driven n=1 infernal mode [2] found to be responsible for disruptions in some discharges. The hybrid kinetic-MagnetoHydroDynamic model has been extended in order to study the influence ofenergetic ICRH-driven minority ions on the stability of low frequency MHD modes. Using a perturbative approach, the modified version of the CASTOR-K[3] code calculates both the real part RE(#delta#W_HOt) and the imaginary part Im(#delta#W_HOT) of the quadratic form #delta#W_HOT, which represents the energetic particle potential energy. IN addition, finite temperature gradients and the effects of collisions of the fast ions are included, which are both relevant for the detailed analysis of the plasma stability in the presence ofenergetic ICRH-driven minority ions. Finite orbit width effects are retained, enabling the study of the influence of both potato and banana orbits.