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Title: Investigations of the impact of cross-field drifts on divertor detachment in DIII-D with UEDGE

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1260497
Report Number(s):
LLNL-CONF-695623
DOE Contract Number:
AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 43rd European Physical Society Conference on Plasma Physics, Leuven, Belgium, Apr 04 - Apr 08, 2016
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION

Citation Formats

Jarvinen, A E, Allen, S L, Groth, M, McLean, A G, Rognlien, T D, Samuell, C M, Briesemeister, A, Fenstermacher, M, Hill, D N, Leonard, A W, and Porter, G D. Investigations of the impact of cross-field drifts on divertor detachment in DIII-D with UEDGE. United States: N. p., 2016. Web.
Jarvinen, A E, Allen, S L, Groth, M, McLean, A G, Rognlien, T D, Samuell, C M, Briesemeister, A, Fenstermacher, M, Hill, D N, Leonard, A W, & Porter, G D. Investigations of the impact of cross-field drifts on divertor detachment in DIII-D with UEDGE. United States.
Jarvinen, A E, Allen, S L, Groth, M, McLean, A G, Rognlien, T D, Samuell, C M, Briesemeister, A, Fenstermacher, M, Hill, D N, Leonard, A W, and Porter, G D. 2016. "Investigations of the impact of cross-field drifts on divertor detachment in DIII-D with UEDGE". United States. doi:. https://www.osti.gov/servlets/purl/1260497.
@article{osti_1260497,
title = {Investigations of the impact of cross-field drifts on divertor detachment in DIII-D with UEDGE},
author = {Jarvinen, A E and Allen, S L and Groth, M and McLean, A G and Rognlien, T D and Samuell, C M and Briesemeister, A and Fenstermacher, M and Hill, D N and Leonard, A W and Porter, G D},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 6
}

Conference:
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  • Simulations using the multi-fluid code UEDGE indicates that, in low confinement (Lmode) plasmas in DIII-D, recycling driven flows dominate poloidal particle flows in the divertor, whereas E×B drift flows dominate the radial particle flows. In contrast, in high confinement (H-mode) conditions E×B drift flows dominate both poloidal and radial particle flows in the divertor. UEDGE indicates that the toroidal C 2+ flow velocities in the divertor plasma are entrained within 30% to the background deuterium flow in both Land H-mode plasmas in the plasma region where the CIII 465 nm emission is measured. Therefore, UEDGE indicates that the Carbon Dopplermore » Coherence Imaging System (CIS), measuring the toroidal velocity of the C 2+ ions, can provide insight to the deuterium flows in the divertor. Parallel-to-B velocity dominates the toroidal divertor flow; direct drift impact being less than 1%. Toroidal divertor flow is predicted to reverse when the magnetic field is reversed. This is explained by the parallel-B flow towards the nearest divertor plate corresponding to opposite toroidal directions in opposite toroidal field configurations. Due to strong poloidal E×B flows in H-mode, net poloidal particle transport can be in opposite direction than the poloidal component of the parallel-B plasma flow.« less
  • Simulations using the multi-fluid code UEDGE indicates that, in low confinement (Lmode) plasmas in DIII-D, recycling driven flows dominate poloidal particle flows in the divertor, whereas E×B drift flows dominate the radial particle flows. In contrast, in high confinement (H-mode) conditions E×B drift flows dominate both poloidal and radial particle flows in the divertor. UEDGE indicates that the toroidal C 2+ flow velocities in the divertor plasma are entrained within 30% to the background deuterium flow in both Land H-mode plasmas in the plasma region where the CIII 465 nm emission is measured. Therefore, UEDGE indicates that the Carbon Dopplermore » Coherence Imaging System (CIS), measuring the toroidal velocity of the C 2+ ions, can provide insight to the deuterium flows in the divertor. Parallel-to-B velocity dominates the toroidal divertor flow; direct drift impact being less than 1%. Toroidal divertor flow is predicted to reverse when the magnetic field is reversed. This is explained by the parallel-B flow towards the nearest divertor plate corresponding to opposite toroidal directions in opposite toroidal field configurations. Due to strong poloidal E×B flows in H-mode, net poloidal particle transport can be in opposite direction than the poloidal component of the parallel-B plasma flow.« less
  • Simulations using the multi-fluid code UEDGE indicates that, in low confinement (L-mode) plasmas in DIII-D, poloidal projection of the ionization driven flows dominate poloidal particle flows in the divertor near the divertor plates, whereas $E × B$ drift flows dominate the radial particle flows. In contrast, in high confinement (H-mode) conditions $E × B$ drift flows dominate both poloidal and radial particle flows in the divertor in the vicinity of the strong gradient region near the separatrix. UEDGE indicates that the toroidal C 2+ flow velocities in the divertor plasmas are mainly entrained within 30% to the background deuterium flowmore » in both L- and H-mode plasmas in the plasma region where the CIII 465 nm emission is measured. Therefore, UEDGE indicates that the Doppler Coherence Imaging Spectroscopy (CIS), measuring the toroidal velocity of the C 2+ ions, can provide insight to the deuterium flows in the divertor. Parallel-to-B velocity dominates the toroidal divertor flow; direct drift impact being less than 1%. Toroidal divertor flow is predicted to reverse when the magnetic field is reversed. This is explained by the parallel-B flow towards the nearest divertor plate corresponding to opposite toroidal directions in opposite toroidal field configurations.« less
  • The flow velocities of deuterons and low charge-state carbon ions have been measured simultaneously for the first time at the crown of the main SOL for low-density plasmas in DIII-D. The dependences of the flow fields on the direction of the cross-field drifts (E x B and B x {del}B) and core plasma rotation were investigated. The measurements indicate that the carbon ion flow direction and magnitude along the magnetic field lines are not necessarily determined by the deuteron flow field, but other physics must also play a role. The deuteron velocities at the plasma crown are high (20-30 km/s)more » in configurations with the ion B x {del}B drift toward the divertor X-point, while nearly zero in configurations with the opposite B x {del}B drift direction. The flow velocities of doubly charged carbon ions are independent of the ion B x {del}B drift direction, and the measurements suggest a stagnation point in the flow field at the crown of the plasma. Both deuteron and carbon ion flow velocities in the SOL were found to be independent of the direction of core plasma rotation. Simulations with the UEDGE code have been carried out to better understand the underlying physics processes. Including the cross-field drifts in the simulations produced divertor solutions that are in significantly closer agreement with the measurements. They do not, however, reproduce the measured flow fields at the crown for the configuration with the ion B x {del}B drift toward the divertor X-point.« less
  • We describe the response of the scrape-off layer (SOL) plasma to variations in the intensity, and geometry of an intrinsic carbon source in DIII-D. Using the multi species 2-D fluid plasma code UEDGE we find plasma modes which are similar to those seen experimentally. At high sputtering coefficient the plasma discontinuously transitions to a state in which the radiation power exceeds the input power and no steady state solution is obtained. We believe this corresponds to the MARFE (Multifaceted Asymmetric Radiation from Edge) state seen experimentally, in which the core confinement is reduced.