CNR ExploRA

Articolo in rivista, 2022, ENG, 10.1088/1361-6587/ac5d9e

Excitation of Alfvén eigenmodes by fusion-born alpha-particles in D-3He plasmas on JET

Kiptily V.G.; Kazakov Y.O.; Nocente M.; Ongena J.; Belli F.; Dreval M.; Craciunescu T.; Eriksson J.; Fitzgerald M.; Giacomelli L.; Goloborodko V.; Iliasova M.V.; Khilkevitch E.M.; Rigamonti D.; Sahlberg A.; Salewski M.; Shevelev A.E.; Garcia J.; Oliver H.J.C.; Sharapov S.E.; Stancar Z.; Weisen H.

United Kingdom Atomic Energy Authority, Culham Centre for Fusion Energy, Culham Science Centre, Oxon, Abingdon, UK; Laboratory for Plasma Physics, LPP-ERM/KMS, Partner in the Trilateral Euregio Cluster (TEC), Brussels, Belgium; Dipartimento di Fisica, Università di Milano-Bicocca, Milan, Italy; Institute for Plasma Science and Technology, National Research Council, Milan, Italy; Unità Tecnica Fusione, ENEA C. R. Frascati (Roma) Italy; Institute of Plasma Physics, National Science Center, Kharkov Institute of Physics and Technology, Ukraine; V.N. Karazin Kharkiv National University, Kharkiv, Ukraine; National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania; Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden; Kyiv Institute for Nuclear Research, Ukraine; Ioffe Physico-Technical Institute, St Petersburg, Russia; Department of Physics, Technical University of Denmark, Kgs. Lyngby, Denmark; CEA, IRFM, Saint-Paul-lez-Durance, France; Joef Stefan Institute, Ljubljana, Slovenia; Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), Switzerland.

Alfvén eigenmode (AE) instabilities driven by alpha-particles have been observed in D-3He fusion experiments on the Joint European Torus (JET) with the ITER-like wall. For the efficient generation of fusion alpha-particles from D-3He fusion reaction, the three-ion radio frequency scenario was used to accelerate the neutral beam injection 100 keV deuterons to higher energies in the core of mixed D-3He plasmas at high concentrations of 3He. A large variety of fast-ion driven magnetohydrodynamic modes were observed, including the elliptical Alfvén eigenmodes (EAEs) with mode numbers n = -1 and axisymmetric modes with n = 0 in the frequency range of EAEs. The simultaneous observation of these modes indicates the presence of rather strong alpha-particle population in the plasma with a 'bump-on-tail' shaped velocity distribution. Linear stability analysis and Fokker-Planck calculations support the observations. Experimental evidence of the AEs excitation by fusion-born alpha-particles in the D-3He plasma is provided by neutron and gamma-ray diagnostics as well as fast-ion loss measurements. We discuss an experimental proposal for the planned full-scale D-T plasma experiments on JET based on the physics insights gained from these experiments.

Plasma physics and controlled fusion (Print) 64 (6), pp. 064001-1–064001-15