EFD–P(11)70

Evidence for a New Path to the Self-Sustainment of the Thermonuclear Fusion Reactions in Magnetically Confined Burning Plasma Experiments

Abstract To achieve a sufficiently high energy gain to become commercially viable, thermonuclear fusion in magnetically confined plasmas relies on collisional heating provided by the MeV-energy, fusionborn alpha particles to replace the external heating initially applied to reach the ion temperature optimising the fusion reactivity. This process for plasma self-heating occurs over time scales five to ten times longer than the energy confinement time, thus can be seriously affected by the magnetohydrodynamic instabilities observed in current experiments. Here we provide the first explanation for observations made in 1997 of unexpected ion heating by fusion-born alpha particles occurring over time scales shorter than the energy confinement time. We demonstrate that non-thermal alpha particles above a critical concentration stabilize the turbulence in the ion-drift direction, therefore significantly reducing an ion energy loss channel. This result opens new perspectives on alternative paths for the self-sustainment of magnetically confined thermonuclear fusion plasmas.
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EFDP11070 556.60 Kb