Modelling of combined ICRF and NBI heating in JET hybrid plasmas

¹ Barcelona Supercomputing Center (BSC), Barcelona, Spain
² ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
³ CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK
⁴ ENEA, Fusion and Nuclear Safety Dep., C.R. Frascati, Frascati (Roma), Italy
⁵ Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland
⁶ Max-Planck-Institut für Plasmaphysik, D-85748 Garching, Germany
⁷ Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw, Poland
⁸ Uppsala University, SE-75120 Uppsala, Sweden
⁹ CEA, IRFM, F-13108 Saint Paul Lez Durance, France
¹⁰ European Commission, B-1049 Brussels, Belgium
¹¹ Laboratory for Plasma Physics, LPP-ERM/KMS, Renaissancelaan 30 Avenue de la Renaissance B-1000, Brussels Belgium
¹² Institute of Physics, Opole University, ul. Oleska 48, Opole 45-052, Poland
¹³ Laboratorio Nacional de Fusión, CIEMAT, Madrid, Spain
¹⁴ ITER Organization, Route de Vinon, CS 90 046, 13067 Saint Paul Lez Durance, France
¹⁵ Consorzio RFX, corso Stati Uniti 4, 35127 Padova, Italy

^* Corresponding author: daniel.gallart@bsc.es

Published online: 23 October 2017

Abstract

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 R_NT. 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 R_NT 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.