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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.

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.

ID 467836
DOI 10.1088/1361-6587/ac5d9e
PRODUCT TYPE Journal Article
LAST UPDATE 2023-01-31T17:59:00Z
TITLE Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium