The Role of Combined ICRF and NBI Heating in JET Hybrid Plasmas in Quest for High D-T Fusion Yield

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: mervi.mantsinen@bsc.es

Published online: 23 October 2017

Abstract

Combined ICRF and NBI heating played a key role in achieving the world-record fusion yield in the first deuterium-tritium campaign at the JET tokamak in 1997. The current plans for JET include new experiments with deuterium-tritium (D-T) plasmas with more ITER-like conditions given the recently installed ITER-like wall (ILW). In the 2015-2016 campaigns, significant efforts have been devoted to the development of high-performance plasma scenarios compatible with ILW in preparation of the forthcoming D-T campaign. Good progress was made in both the inductive (baseline) and the hybrid scenario: a new record JET ILW fusion yield with a significantly extended duration of the high-performance phase was achieved. This paper reports on the progress with the hybrid scenario which is a candidate for ITER longpulse operation (∼1000 s) thanks to its improved normalized confinement, reduced plasma current and higher plasma beta with respect to the ITER reference baseline scenario. The combined NBI+ICRF power in the hybrid scenario was increased to 33 MW and the record fusion yield, averaged over 100 ms, to 2.9x10¹⁶ neutrons/s from the 2014 ILW fusion record of 2.3x10¹⁶ neutrons/s. Impurity control with ICRF waves was one of the key means for extending the duration of the high-performance phase. The main results are reviewed covering both key core and edge plasma issues.