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| IT06 · Observation and Modelling of Fast Ion Loss
1Max-Planck Institut für Plasmaphysik, EURATOM-Assoziation, Boltzmannstraße 2, D-85748 Garching,
Germany Email: Simon.Pinches@ipp.mpg.de
Abstract: The confinement of fast particles is of crucial
importance for the success of future burning plasma experiments. On JET, the
confinement of ICRF accelerated fast hydrogen ions with energies exceeding 5
MeV has been measured using the characteristic -rays emitted through their inelastic scattering with
carbon impurities, 12C(p,p'g)12C. Recent experiments have shown a significant decrease in this
gamma-ray emission (by a factor of 2) during so-called
tornado mode activity (core-localised TAEs within the q = 1 surface) in
sawtoothing plasmas. This is indicative of a significant loss or extensive
re-distribution of these (5 MeV) particles from the plasma core. In this
paper, mechanisms responsible for the radial transport and loss of these
fast ions are investigated and identified using the HAGIS code, which
describes the interaction of the fast ions and the TAE observed. The
calculations show that the overlap of wave-particle resonances in
phase-space leads to an enhanced radial transport and loss. On both JET and
ASDEX Upgrade, new fast ion loss detectors have been installed to further
investigate the loss of such particles. On JET, fast ion loss detectors
based around an array of Faraday cups and a scintillator probe have been
installed as part of a suite of diagnostic enhancements. On ASDEX Upgrade, a
new fast ion loss detector has been mounted on the mid-plane manipulator
allowing high resolution measurements in pitch angle, energy and time. This
has enabled the direct observation of fast ion losses during various MHD
phenomena to be studied in detail. ELM induced fast ion losses have been
directly observed along with the enhancement of fast ion losses from
specific areas of phase-space in the presence of NTMs and TAEs. Note: In special issue in Nuclear Fusion - volume 46, issue 10
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Synopsis
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