KINETIC BALLOONING MODES AT THE TOKAMAK TRANSPORT BARRIER WITH NEGATIVE MAGNETIC SHEAR

Stability of the kinetic ballooning modes is investigated for plasma p arameters at the internal transport barrier in tokamak discharges with negative magnetic shear employing a kinetic shooting code with long s hooting distance. It is found that the second stability regime with re spect to the pressure gradient parameter, which was predicted for nega tive shear [A. Hirose and M. Elia, Phys. Rev. Lett. 76, 628 (1996)], c an possibly disappear. The mode with comparatively low toroidal mode n umber and mode frequency below 100 kHz is found to be destabilized mar ginally only around the transport barrier characterized by steep press ure and density gradients. (C) 1997 American Institute of Physics. [S1 070-664X(97)01411-0].