Three-dimensional dynamics of fluctuations appearing during pellet ablation process around a pellet in a fusion plasma experiment

Autor: Ohshima, S., Suzuki, T., Matoike, R., Motojima, G., Kado, S., Mori, A., Miyashita, A., Kobayashi, S., Minami, T., Iwata, A., Qiu, D., Wang, C., Luo, M., Zhang, P., Kondo, Y., Nishino, N., Mizuuchi, T., Okada, H., Konoshima, S., Inagaki, S., Nagasaki, K.
Rok vydání: 2022
Předmět:
Zdroj: Scientific Reports. 12
ISSN: 2045-2322
Popis: Understanding pellet ablation physics is crucial to realizing efficient fueling into a high temperature plasma for the steady state operation of ITER and future fusion reactors. Here we report the first observation of the formation of fluctuation structures in the pellet plasmoid during the pellet ablation process by a fast camera in a medium-sized fusion device, Heliotron J. The fluctuation has a normalized fluctuation level of ~ 15% and propagates around the moving pellet across the magnetic field. By comparing the fluctuation structures with the shape of magnetic field lines calculated with the field line tracing code, we successfully reconstruct the spatio-temporal structure of the fluctuations during the pellet ablation process. The fluctuations are located at the locations displaced toroidally from the pellet and propagate in the cross-field direction around the pellet axis along the field line, indicating a three-dimensional behavior and structure of fluctuations. The fluctuation would be driven by a strong inhomogeneity formed around the pellet and invoke the relaxation of the gradient through a cross-field transport induced by the fluctuations, which could affect the pellet ablation and pellet fueling processes. Such fluctuations can be ubiquitously present at the inhomogeneity formed around a pellet in the pellet ablation process in fusion devices.
核融合プラズマへの燃料供給ペレット周辺の極限状況下に現れる“揺らぎ”構造の発見 --核融合炉の持続的燃焼の制御向上への貢献に期待--. 京都大学プレスリリース. 2022-09-30.
Databáze: OpenAIRE
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