EPJ Web of Conferences (Jan 2017)

Modelling of combined ICRF and NBI heating in JET hybrid plasmas

  • Gallart Dani,
  • Mantsinen Mervi,
  • Challis Clive,
  • Frigione Domenico,
  • Graves Jonathan,
  • Hobirk Joerg,
  • Belonohy Eva,
  • Czarnecka Agata,
  • Eriksson Jacob,
  • Goniche Marc,
  • Hellesen Carl,
  • Jacquet Philippe,
  • Joffrin Emmanuel,
  • Krawczyk Natalia,
  • King Damian,
  • Lennholm Morten,
  • Lerche Ernesto,
  • Pawelec Ewa,
  • Sips George,
  • Solano Emilia,
  • Tsalas Maximos,
  • Valisa Marco

DOI
https://doi.org/10.1051/epjconf/201715703015
Journal volume & issue
Vol. 157
p. 03015

Abstract

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During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H) at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.