The effects of anisotropy and plasma rotation on the stabilisation of the internal kink mode by NBI
The internal kink instability is analysed for flowing anisotropic toroidal plasma. The investigation focuses on modelling JET neutral beam injection (NBI) discharges which can maintain sheared plasma rotation frequencies of up to 30 kHz and strongly anisotropic distributions of minority ions. While the effect of such sub-sonic plasma flow on the MHD internal kink stability is typically modest, it is seen that the kinetic response of the NBI ions is sensitive to plasma rotation. In this respect the work extends the analysis of plasmas in the banana regime where it is found that thermal ions give rise to kinetic contributions that are strongly modified by sub-sonic sheared toroidal plasma rotation. In addition, for auxiliary heated plasmas it is necessary to generalize the toroidal internal kink instability to take into account anisotropic equilibria. A fluid contribution to the potential energy deltaW is identified as being sensitive to weak anisotropy, and comparisons are made with an existing expression for this term. By accurately accounting for the effects of passing and trapped ions it is possible to analyse the dependence of fast ion stability on neutral beam injection angle.
Bibliographic Reference: A paper presented at the Joint Varenna-Lausanne International Workshop on "Theory of Fusion Plasmas", Varenna, Italy, August 27-30 2002, and published in EPFL Internal report 737/02, October 2002, pp.27-32.
Availability: Available free of charge from: École Polytechnique Fédérale de Lausanne (EPFL), Ecublens, CH-1015 Lausanne Fax +41-21-6934747 Available online on the workshop website: http://varenna-lausanne.epfl.ch/
Record Number: 200215542 / Last updated on: 2002-11-20
Original language: en
Available languages: en