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:

Munaretto, S.  ^[1];

• Search DOE PAGES for author "Munaretto, S."
• Search DOE PAGES for ORCID "0000-0003-1465-0971"

Evans, T. E.  ^[1];

• Search DOE PAGES for author "Evans, T. E."
• Search DOE PAGES for ORCID "0000-0002-8357-5859"

Ferraro, N. M. ^[2]; Orlov, D. M.  ^[3];

• Search DOE PAGES for author "Orlov, D. M."
• Search DOE PAGES for ORCID "0000-0002-2230-457X"

Trevisan, G. L.  ^[4];

• Search DOE PAGES for author "Trevisan, G. L."
• Search DOE PAGES for ORCID "0000-0003-4920-6109"

Wu, W. ^[1]

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+ Show Author Affiliations

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:

Wed Jun 12 00:00:00 EDT 2019

Research Org.:

General Atomics, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES)

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:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MHD; footprints; error fields