EFDA-JET-CP(04)03/50
Experiment on Tritium Beam Evolution in JET Plasmas with Fishbones and TAE-Modes
Energetic ions with velocities comparable to Alfvén velocity VA can destabilize Alfvén Eigenmodes in tokamaks through resonant wave-particle interaction. At low magnetic field, B 1T, the Alfven velocity is sufficiently small for resonance, V||beam VA, between the wave and NBI-produced ions at ENBI ~ 80-160keV typical for present-day tokamaks. Experiments on the destabilization of TAEs by NBI at low B have been performed on TFTR, DIII-D, and JET. The experiments on JET have shown that TAEs and very high amplitude n = 1 fishbones are destabilised by NBI with Vbeam 0.85VA and powers up to 10MW, if the safety factor is below one, q(0)<1. It was found that the fishbones significantly affect both the neutron rate determined by the beam-plasma reactions and the total energy content of the plasma. A similar experiment dedicated to measurements of the NBI power deposition profile and its redistribution by TAEs/fishbones was performed in 2003 Trace Tritium campaign. The experiment was based on using neutron profile monitor on JET for measuring the profiles of Tritium NBI injected in blips into deuterium plasma with TAEs/fishbones.