Scenario preparation for the observation of alpha-driven instabilities and transport of alpha particles in JET DT plasmas
Résumé
In next-step fusion devices, toroidal Alfvén eigenmodes (TAEs) can be excited by the alpha particles resulting from DT fusion reactions, and may induce a significant redistribution of the energetic ions present in the discharge. During the last JET deuterium campaigns, a substantial experimental effort has been devoted to preparing scenarios maximizing the likelihood of observing alpha-driven TAEs in a future JET DT campaign. Discharges at low densities, large core temperatures associated with the presence of internal transport barriers and characterised by good energetic ion confinement have been performed. ICRH has been used in minority heating regimes to probe the TAE stability, and has resulted in the observation of core-localized modes. Significant progress has been achieved recently in order to make the scenario ready to be run in DT. This has included the test of ELM control methods, afterglow triggering using a dedicated real-time algorithm, and fuel introduction with T-compatible gas injectors. Extrapolated simulations of the best performing pulses to DT motivate the completion of this preparation effort in view of forthcoming JET DT campaigns.
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