Fast imaging of filaments in the X-point region of Alcator C-Mod

Terry, J. L.; Ballinger, S.; Brunner, D.; LaBombard, B.; White, A. E.; Zweben, S. J.

doi:10.1016/j.nme.2016.11.020

Fast imaging of filaments in the X-point region of Alcator C-Mod

Journal Article · Fri Jan 27 00:00:00 EST 2017 · Nuclear Materials and Energy

DOI:https://doi.org/10.1016/j.nme.2016.11.020· OSTI ID:1349257

^[1]; ^[2]; Brunner, D. ^[1]; LaBombard, B. ^[1]; White, A. E. ^[1]; ^[3]

Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Columbia Univ., New York, NY (United States)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

A rich variety of field-aligned fluctuations has been revealed using fast imaging of D_α emission from Alcator C-Mod's lower X-point region. Field-aligned filamentary fluctuations are observed along the inner divertor leg, within the Private-Flux-Zone (PFZ), in the Scrape-Off Layer (SOL) outside the outer divertor leg, and, under some conditions, at or above the X-point. The locations and dynamics of the filaments in these regions are strikingly complex in C-Mod. Changes in the filaments’ generation appear to be ordered by plasma density and magnetic configuration. Filaments are not observed for plasmas with n/n_Greenwald ≲ 0.12 nor are they observed in Upper Single Null configurations. In a Lower Single Null with 0.12 ≲ n/n_Greenwald ≲ 0.45 and Bx∇B directed down, filaments typically move up the inner divertor leg toward the X-point. Reversing the field direction results in the appearance of filaments outside of the outer divertor leg. With the divertor targets “detached”, filaments inside the LCFS are seen. Lastly, these studies were motivated by observations of filaments in the X-point and PFZ regions in MAST, and comparisons with those observations are made.

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE

Contributing Organization:: Columbia University, New York, NY; MIT Plasma Science and Fusion Center, Cambridge, MA USA

Grant/Contract Number:: FC02-99ER54512

OSTI ID:: 1349257

Alternate ID(s):: OSTI ID: 22834559

Journal Information:: Nuclear Materials and Energy, Journal Name: Nuclear Materials and Energy Vol. 12; ISSN 2352-1791

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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Cited By (3)

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices Zweben, S. J.; Terry, J. L.; Stotler, D. P. Review of Scientific Instruments, Vol. 88, Issue 4 https://doi.org/10.1063/1.4981873	journal	April 2017
Divertor leg filaments in NSTX-U Scotti, Filippo; Zweben, Stewart; Soukhanovskii, Vlad Nuclear Fusion, Vol. 58, Issue 12 https://doi.org/10.1088/1741-4326/aae49f	journal	October 2018
Disconnection of scrape off layer turbulence between the outer midplane and divertor target plate in NSTX Scotti, F.; Zweben, S.; Myra, J. Nuclear Fusion, Vol. 60, Issue 2 https://doi.org/10.1088/1741-4326/ab5886	journal	December 2019

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Fast imaging of filaments in the X-point region of Alcator C-Mod

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