Internal Transport Barrier Driven by Redistribution of Energetic Ions
Authors: K.L. Wong, W.W. Heidbrink, E. Ruskov, C.C. Petty, C.M. Greenfield, R. Nazikian, and R. Budny
Date of PPPL Report: November 2004
Published in: Nucl. Fusion 45:1 (January 2005) 30-39.
Alfvèn instabilities excited by energetic ions are used as a means to reduce the central magnetic shear in a tokamak via redistribution of energetic ions. When the central magnetic shear is low enough, ballooning modes become stable for any plasma pressure gradient and an internal transport barrier (ITB) with a steep pressure gradient can exist. This mechanism can sustain a steady-state ITB as demonstrated by experimental data from the DIII-D tokamak. It can also produce a shear in toroidal and poloidal plasma rotation. Possible application of this technique to use the energetic alpha particles for improvement of burning plasma performance is discussed.