SMuK 2021 – scientific programme

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P: Fachverband Plasmaphysik

P 5: Poster I

P 5.15: Poster

Tuesday, August 31, 2021, 14:00–16:00, P

Self-similar expansion of a plasmoid supplied by pellet ablation — •Alistair Arnold, Pavel Aleynikov, and Per Helander — Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald

Cryogenic pellet injection is an important means of refuelling and terminating fusion plasmas, with fuel pellets exhibiting a range of phenomena beneficial to confinement and the energy balance between ions and electrons. We consider the self-similar expansion along magnetic field lines of the plasmoid produced by a small pellet. In particular, we consider the case when the expansion timescale is comparable to the time taken for the pellet gas cloud to cross a field line. It is shown that plasmoid ions acquire a significant fraction of the energy that is transferred to plasmoid electrons via collisions with the ambient plasma. This expansion is insensitive to the details of the profile of the gas cloud and details of ionisation - the plasma flux emerging from the gas cloud is the only quantity that affects the expansion.