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Time-dependent probability density function analysis of H-mode transitions

Farre-Kaga, Hiro J.·Andrew, Yasmin (ORCID:0000000300943503)·Dunsmore, Jamie·Kim, Eun-jin·Rhodes, Terry L.·Schmitz, Lothar·Yan, Zheng
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Abstract

Abstract The first application of time-dependent probability density function (PDF) analysis to the L-H transition in fusion plasmas is presented. PDFs are constructed using Doppler Backscattering data of perpendicular fluctuation velocity, , and turbulence from the edge region of the DIII-D tokamak. These raw time-series data are sliced into millisecond-long sliding time-windows to create PDFs. During the transition, the PDFs develop strong right tails, indicative of turbulence-suppressing localised flows in the plasma edge; such features and other subtle behaviours are explored using novel information geometry techniques. This letter examines the applicability of these techniques to predict L-H transitions and investigate predator-prey self-regulation theories between turbulence and perpendicular velocity.

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70 PLASMA PHYSICS AND FUSION TECHNOLOGYPhysics

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Farre-Kaga, Hiro J., Andrew, Yasmin (ORCID:0000000300943503), Dunsmore, Jamie, Kim, Eun-jin, Rhodes, Terry L., Schmitz, Lothar, Yan, Zheng. 2023-06-07. Time-dependent probability density function analysis of H-mode transitions. https://doi.org/10.1209/0295-5075%2Facd955

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