Time-dependent probability density function analysis of H-mode transitions
Open Access
- 1 June 2023
- journal article
- research article
- Published by IOP Publishing in Europhysics Letters
- Vol. 142 (6) , 64001
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.Keywords
Funding Information
- Fusion Energy Sciences (DE-FC02-04ER54698)
- Fusion Energy Sciences (DE-FG02-08ER54999)
- Fusion Energy Sciences (DE-SC-0020287)
- Fusion Energy Sciences (DE-SC0019352)
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