Greifswald 2024 – scientific programme

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P: Fachverband Plasmaphysik

P 12: Poster II

P 12.2: Poster

Tuesday, February 27, 2024, 16:30–18:30, ELP 6: Foyer

Influence of density-potential cross-phase on particle and momentum transport in TJ-K — •Ralph Sarkis, Mirko Ramisch, and Günter Tovar — IGVP, University of Stuttgart, Germany

Transport formation in magnetically confined plasmas is heavily dependent on the coupling between density and potential. Drift-waves can be destabilized when the electron response to a density perturbation is hindered and the positive potential perturbation that arises has a non-zero phase shift with respect to the density perturbation. The momentum transport, also called Reynolds stress, and particle transport have opposite promoting conditions with respect to the density-potential coupling, that is highly coupled and decoupled, respectively. To understand the conflicting occurrence of both transport phenomena peaking at comparable poloidal positions, as observed at the stellarator experiment TJ-K, a spatio-temporal analysis is performed by means of a poloidal Langmuir probe array, which allows for the spectral decomposition in order to determine the transports' interplay on the basis of the coupling/decoupling influence. Conditional sampling reveals a separation of particle and momentum transport peaks in time. Both transports dynamics are related to the evolution of the density-potential cross-phase in time, and differentiated from the amplitude modulation, to establish a time-based relation between the spectral components and the transport events. Scale separation of the components and of the transport phenomena in the time-based analyses provides a deeper insight of the weighted contribution of each scale investigated.