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(THP2/24) Stability Analysis of Energetic Ion Alfvén Mode and Kinetic Ballooning Mode in Tokamaks

   
A. Hirose , M. Elia 
Plasma Physics Laboratory, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
 
M. Yamagiwa 
Advanced Photon Research Center, Japan Atomic Energy Research Institute, 2-4 Tokai, Naka, Ibaraki 319-1195, Japan

Abstract
Kinetic ballooning analysis has been performed for high performance tokamak discharges by implementing the Shafranov shift  $\Delta'$ in both positive and negative shear  regimes. For discharge parameters pertinent to the transport barriers  characterized by steep pressure gradient and large $\Delta'$, the kinetic ballooning and drift type modes are stabilized at $\Delta' \simeq -0.3 \sim -0.2$. A new MHD type ballooning mode with large growth rates is predicted for excessively large $\Delta'$ in negative shear regime. Also investigated is the Alfven mode driven by energetic ions (such as trapped alpha particles ) without resorting to the conventional ideal MHD assumption for the bulk ions. Compared with earlier predictions, a reduction in the growth rate by two orders of magnitude has been seen.

   

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