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Title: Assessment of equilibrium field coil misalignments on the divertor footprints in NSTX-U

Abstract

The presence of error fields in a tokamak device is inevitable, so it is of fundamental importance to understand their impact on the operation of the device and therefore up to what level they can be tolerated. In this paper a prediction of the impact on the magnetic footprints on the divertor plates due to the misalignment of NSTX-U equilibrium coils is presented. Resistive MHD solutions are used to predict the magnetic field perturbations experienced by the field lines due to the presence of error fields. A linear relation between the magnitude of the misalignment and the area of the magnetic footprints is found, as well as an inverse proportionality between the size of a magnetic footprint and the plasma penetration of the field lines composing the footprint. This study is intended as a starting point in the process of investigating divertor footprints associated with the plasma response to intrinsic error fields with resistive MHD codes. A basic interpretation of the results suggests that large footprints resulting from equilibrium coils misalignment may be desirable, to some extent, to decrease the peak heat load on the divertor components. Lastly, a more complete interpretation of the results presented here will involve amore » number of complex physics issues, for example pedestal transport and stability along with the role of various scrape-off layer and divertor processes, as well as experimental data to confirm the predictions.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [4];  [1]
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Univ. of California - San Diego, La Jolla, CA (United States)
  4. General Atomics, San Diego, CA (United States); Oak Ridge Associated Univ., Oak Ridge, TN (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1526726
Report Number(s):
DOE-GA-54698
Journal ID: ISSN 0029-5515
Grant/Contract Number:  
FC02-04ER54698
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 7; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
MHD; footprints; error fields

Citation Formats

Munaretto, S., Evans, T. E., Ferraro, N. M., Orlov, D. M., Trevisan, G. L., and Wu, W. Assessment of equilibrium field coil misalignments on the divertor footprints in NSTX-U. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab1ee0.
Munaretto, S., Evans, T. E., Ferraro, N. M., Orlov, D. M., Trevisan, G. L., & Wu, W. Assessment of equilibrium field coil misalignments on the divertor footprints in NSTX-U. United States. doi:10.1088/1741-4326/ab1ee0.
Munaretto, S., Evans, T. E., Ferraro, N. M., Orlov, D. M., Trevisan, G. L., and Wu, W. Wed . "Assessment of equilibrium field coil misalignments on the divertor footprints in NSTX-U". United States. doi:10.1088/1741-4326/ab1ee0.
@article{osti_1526726,
title = {Assessment of equilibrium field coil misalignments on the divertor footprints in NSTX-U},
author = {Munaretto, S. and Evans, T. E. and Ferraro, N. M. and Orlov, D. M. and Trevisan, G. L. and Wu, W.},
abstractNote = {The presence of error fields in a tokamak device is inevitable, so it is of fundamental importance to understand their impact on the operation of the device and therefore up to what level they can be tolerated. In this paper a prediction of the impact on the magnetic footprints on the divertor plates due to the misalignment of NSTX-U equilibrium coils is presented. Resistive MHD solutions are used to predict the magnetic field perturbations experienced by the field lines due to the presence of error fields. A linear relation between the magnitude of the misalignment and the area of the magnetic footprints is found, as well as an inverse proportionality between the size of a magnetic footprint and the plasma penetration of the field lines composing the footprint. This study is intended as a starting point in the process of investigating divertor footprints associated with the plasma response to intrinsic error fields with resistive MHD codes. A basic interpretation of the results suggests that large footprints resulting from equilibrium coils misalignment may be desirable, to some extent, to decrease the peak heat load on the divertor components. Lastly, a more complete interpretation of the results presented here will involve a number of complex physics issues, for example pedestal transport and stability along with the role of various scrape-off layer and divertor processes, as well as experimental data to confirm the predictions.},
doi = {10.1088/1741-4326/ab1ee0},
journal = {Nuclear Fusion},
number = 7,
volume = 59,
place = {United States},
year = {2019},
month = {6}
}

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This content will become publicly available on June 12, 2020
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