Kinetic ion effect on geodesic acoustic Alfvén modes in tokamaks
Abstract
Using a quasitoroidal set of coordinates with coaxial circular magnetic surfaces, the Vlasov equation is solved for collisionless plasmas, and the dielectric tensor is found for large aspect ratio tokamaks in a low frequency band. Taking into account q-profile and charge separation parallel electric field, it is found that the Alfvén wave continuum is deformed by ion geodesic effects producing continuum minimum at the rational magnetic surfaces. Low frequency geodesic ion induced Alfvén waves are found below the continuum minimum where collisionless damping has a gap for Maxwell distribution. In kinetic approach, the ion thermal motion defines the geodesic effect but the mode frequency is strongly corrected due to parallel motion of electrons.
- Publication:
-
Physics of Plasmas
- Pub Date:
- March 2009
- DOI:
- 10.1063/1.3081547
- Bibcode:
- 2009PhPl...16c4501E
- Keywords:
-
- 52.35.Bj;
- 52.25.Fi;
- 52.65.Ff;
- 52.55.Fa;
- Magnetohydrodynamic waves;
- Transport properties;
- Fokker-Planck and Vlasov equation;
- Tokamaks spherical tokamaks