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High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak

Harvard Dataverse (Africa Rice Center, Bioversity International, CCAFS, CIAT, IFPRI, IRRI and WorldFish)

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Title High resolution density pedestal measurements during edge localized modes by short-pulse reflectometry in the TCV tokamak
 
Identifier https://doi.org/10.7910/DVN/CWP7FN
 
Creator Molina Cabrera, P.A.; Labit, B.; Coda, S.; Porte, L.
 
Publisher Harvard Dataverse
 
Description This publication presents high spatio-temporal resolution (mm/μs) density profile measurements of the pedestal top during type I, III, and small edge localized mode (ELM) H-mode plasmas in the Tokamak à Configuration Variable (TCV). These measurements were performed using a novel short-pulse reflectometer. Average inter-ELM density profiles are obtained via conditional averaging using the Dα trace as ELM indicator. Changes to the pedestal density profile gradients prior to type-III ELMs reveal unique pedestal dynamics leading to the ELM crash which can provide important experimental data for validation of non-linear MHD ELM simulations. The small-ELM scenario is found to feature a ∼25-35 kHz quasi-coherent density fluctuation near the separatrix rho_psi ∼0.993-1.05 not observed during a similar type-I ELM discharge. This oscillation is also found in low-field-side magnetic pick- up probes displaying a ballooning character and n=+1 toroidal mode number. This oscillation could help explain the markedly different pedestal dynamics observed in the small-ELM regime.
 
Subject Physics
density fluctuation
density pedestal
density profile
edgelocalized modes
high resolution
low-field sides
spatio-temporal resolution
toroidal mode numbers