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Title: Exploring drift effects in TCV single-null plasmas with the UEDGE code

Abstract

This study explores the effects of particle drifts across the magnetic field in TCV single-null plasmas using the two-dimensional edge plasma transport code UEDGE. In particular, it aims to reproduce a double-peaked density target profile, a feature which has been observed both at JET and in a TCV forward-field ($${\rm{\nabla }}B$$ drift of core ions towards the X-point) discharge. Initial simulations are performed with drift effects turned off. This allows identification of the input parameters that strongly influence the computed steady-state but are not well known from the experiment. Including cross-field drifts self-consistently in the simulations brings computed profiles at the inner target closer to the experiment, with the double peak being reproduced for the density. In agreement with the experiment, simulations of a similar reversed-field shot yield lower n e and higher T e at the inner target, as well as unchanged temperatures at the outer plate. However, several discrepancies remain. In the forward field case, the inner target density peak near the separatrix is much sharper than seen experimentally. Furthermore, simulations show a strong dependence of the outer plate density and of the outer/inner power sharing on toroidal field direction. Experimentally, no such dependencies are observed. In the simulations, the changes of target profiles with field direction are mainly due to E × B drifts in the divertor region. Finally, while these simulations highlight the importance of E × B drifts in these TCV plasmas, the remaining differences with the experiment indicate that their role is overestimated in the simulations.

Authors:
 [1]; ORCiD logo [2];  [3];  [3];  [2];  [2];  [2]
  1. École Polytechnique Fédérale de Lausanne (EPFL) (Switzlerland). Swiss Plasma Center (SPC); Univ. of Oxford (United Kingdom). Rudolf Peierls Centre for Theoretical Physics
  2. École Polytechnique Fédérale de Lausanne (EPFL) (Switzlerland). Swiss Plasma Center (SPC)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); École Polytechnique Fédérale de Lausanne (EPFL) (Switzlerland)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1465288
Report Number(s):
LLNL-JRNL-746959
Journal ID: ISSN 0741-3335; 931709; TRN: US1902463
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 10; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; TCV; UEDGE; drifts; single-null

Citation Formats

Christen, N., Theiler, C., Rognlien, T. D., Rensink, M. E., Reimerdes, H., Maurizio, R., and Labit, B. Exploring drift effects in TCV single-null plasmas with the UEDGE code. United States: N. p., 2017. Web. https://doi.org/10.1088/1361-6587/aa7c8e.
Christen, N., Theiler, C., Rognlien, T. D., Rensink, M. E., Reimerdes, H., Maurizio, R., & Labit, B. Exploring drift effects in TCV single-null plasmas with the UEDGE code. United States. https://doi.org/10.1088/1361-6587/aa7c8e
Christen, N., Theiler, C., Rognlien, T. D., Rensink, M. E., Reimerdes, H., Maurizio, R., and Labit, B. Thu . "Exploring drift effects in TCV single-null plasmas with the UEDGE code". United States. https://doi.org/10.1088/1361-6587/aa7c8e. https://www.osti.gov/servlets/purl/1465288.
@article{osti_1465288,
title = {Exploring drift effects in TCV single-null plasmas with the UEDGE code},
author = {Christen, N. and Theiler, C. and Rognlien, T. D. and Rensink, M. E. and Reimerdes, H. and Maurizio, R. and Labit, B.},
abstractNote = {This study explores the effects of particle drifts across the magnetic field in TCV single-null plasmas using the two-dimensional edge plasma transport code UEDGE. In particular, it aims to reproduce a double-peaked density target profile, a feature which has been observed both at JET and in a TCV forward-field (${\rm{\nabla }}B$ drift of core ions towards the X-point) discharge. Initial simulations are performed with drift effects turned off. This allows identification of the input parameters that strongly influence the computed steady-state but are not well known from the experiment. Including cross-field drifts self-consistently in the simulations brings computed profiles at the inner target closer to the experiment, with the double peak being reproduced for the density. In agreement with the experiment, simulations of a similar reversed-field shot yield lower n e and higher T e at the inner target, as well as unchanged temperatures at the outer plate. However, several discrepancies remain. In the forward field case, the inner target density peak near the separatrix is much sharper than seen experimentally. Furthermore, simulations show a strong dependence of the outer plate density and of the outer/inner power sharing on toroidal field direction. Experimentally, no such dependencies are observed. In the simulations, the changes of target profiles with field direction are mainly due to E × B drifts in the divertor region. Finally, while these simulations highlight the importance of E × B drifts in these TCV plasmas, the remaining differences with the experiment indicate that their role is overestimated in the simulations.},
doi = {10.1088/1361-6587/aa7c8e},
journal = {Plasma Physics and Controlled Fusion},
number = 10,
volume = 59,
place = {United States},
year = {2017},
month = {6}
}

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Works referenced in this record:

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    Works referencing / citing this record:

    UEDGE modelling of detached divertor operation for long-leg divertor geometries in ARC
    journal, March 2018

    • Wigram, M.; LaBombard, B.; Umansky, M. V.
    • Contributions to Plasma Physics, Vol. 58, Issue 6-8
    • DOI: 10.1002/ctpp.201700178

    Progress toward divertor detachment on TCV within H-mode operating parameters
    journal, May 2019

    • Harrison, J. R.; Theiler, C.; Février, O.
    • Plasma Physics and Controlled Fusion, Vol. 61, Issue 6
    • DOI: 10.1088/1361-6587/ab140e

    Simulations of divertor heat flux width using transport code with cross-field drifts under the BOUT++ framework
    journal, January 2020

    • Li, N. M.; Xu, X. Q.; Hughes, J. W.
    • AIP Advances, Vol. 10, Issue 1
    • DOI: 10.1063/1.5126884

    Physics research on the TCV tokamak facility: from conventional to alternative scenarios and beyond
    journal, August 2019


    The effect of the secondary x-point on the scrape-off layer transport in the TCV snowflake minus divertor
    journal, December 2018