Ion cyclotron heating induced fast ion transport and plasma rotation in tokamaks

V. S. Chan
2001 AIP Conference Proceedings  
Minority ion cyclotron heating can produce energetic ions with banana orbits that are finite compared with the minor radius of a tokamak. The radial transport of the fast ions in the presence of Coulomb collisions results in a radial current and a corresponding J×B torque density on the bulk plasma. Collisions between the minority ions and majority ions provides and additional frictional torque that adds to or opposes the magnetic torque. Our study uses a code which follows the particle drift
more » ... ajectories in a tokamak geometry under the influence of rf fields and collisions, modeled with an rf-quasilinear operator and a Monte-Carlo operator, respectively. It is shown that when the regions of negative and positive torque density are spatially separated, a finite central rotation velocity can result even when the volume integrated torque density is small. This is consistent with the results of Perkins [F.W. Perkins, et al., "Generation of Plasma Rotation in a Tokamak by Ion-Cyclotron Absorption of Fast Alfvén Waves," to appear in Phys. Plasmas, 2001], that uses a different approach. A physical picture emerges explaining the co-and counter-rotation with low-and high-field resonance respectively as a consequence of finite orbit width. The model also provides details of the rotation profile when ions are continuously being heated and slowed down in steady-state. Qualitative comparison with recent JET results will be discussed.
doi:10.1063/1.1424214 fatcat:avc5ikadznau7icyvoaffrxn3y