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

Journal Article · · Europhysics Letters
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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.

Sponsoring Organization:
USDOE
Grant/Contract Number:
NONE; SC0020287; SC0019352; FG02-08ER54999; FC02-04ER54698
OSTI ID:
1984182
Journal Information:
Europhysics Letters, Journal Name: Europhysics Letters Journal Issue: 6 Vol. 142; ISSN 0295-5075
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
France
Language:
English

References (12)

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A novel, multichannel, comb-frequency Doppler backscatter system journal October 2010
Time-dependent probability density functions and information diagnostics in forward and backward processes in a stochastic prey–predator model of fusion plasmas journal October 2020
The role of turbulence–flow interactions in L- to H-mode transition dynamics: recent progress journal January 2017
Staged approach towards physics-based L-H transition models journal September 2020
H-mode plasmas in the pre-fusion power operation 1 phase of the ITER research plan journal June 2021
Mean and Oscillating Plasma Flows and Turbulence Interactions across the L − H Confinement Transition journal February 2011
Spatiotemporal Structure of the Interaction between Turbulence and Flows at the L-H Transition in a Toroidal Plasma journal December 2011
Role of Zonal Flow Predator-Prey Oscillations in Triggering the Transition to H-Mode Confinement journal April 2012
Regime of Improved Confinement and High Beta in Neutral-Beam-Heated Divertor Discharges of the ASDEX Tokamak journal November 1982
Remarks on Some Nonparametric Estimates of a Density Function journal September 1956
Information Geometry, Fluctuations, Non-Equilibrium Thermodynamics, and Geodesics in Complex Systems journal October 2021

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