Redistribution of ICRH fast ions in the presence of fishbones and Alfvén eigenmodes
2007 (English)In: 34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts, 2007, no 1, 607-610 p.Conference paper (Refereed)
A set of experiments on fast ion redistribution was carried out in recent JET campaigns, in which the new fast ion loss detectors were used for the first time . This paper reports on the experiments carried out with low density plasmas and high ICRH power, a scenario that allow large populations of highly energetic fast ions to be built up and a variety of instabilities to be destabilized. Fast ion losses were successfully measured and it could be confirmed they were effectively associated to MHD activity. Losses occurred at considerably high energies (of the order of few MeV) and two types of fast ions were identified by the gamma-ray diagnostics : fast protons with an energetic tail in excess of 4.5 MeV due to ICRH tuned to a fundamental H-resonance in the centre of the plasmas and D-ions accelerated with second harmonic heating whose energies exceeded 0.5 MeV. Three types of losses were identified, one associated with sawtooth crashes, one associated with TAE and high frequency fishbones and a third group that seems to correlate with tornado modes. When tornado modes became unstable, a significant increase in the number of losses was measured and a change in both the energy and pitch angle of the lost ions was observed. In addition, it was also observed that the number of losses increased significantly with the ICRH power.
Place, publisher, year, edition, pages
2007. no 1, 607-610 p.
Experiments, Plasma diagnostics, Plasmas, Tokamak devices, Tornadoes
IdentifiersURN: urn:nbn:se:kth:diva-154676ScopusID: 2-s2.0-84873802977ISBN: 978-162276334-4OAI: oai:DiVA.org:kth-154676DiVA: diva2:758503
34th European Physical Society Conference on Plasma Physics 2007, EPS 2007, 2 July 2007 through 6 July 2007, Warsaw, Poland
QC 201410272014-10-272014-10-272014-10-27Bibliographically approved