Title: Predict-first experimental analysis using automated and integrated magnetohydrodynamic modeling

Abstract

An integrated-modeling workflow has been developed in this paper for the purpose of performing predict-first analysis of transient-stability experiments. Starting from an existing equilibrium reconstruction from a past experiment, the workflow couples together the EFIT Grad-Shafranov solver [L. Lao et al., Fusion Sci. Technol. 48, 968 (2005)], the EPED model for the pedestal structure [P. B. Snyder et al., Phys. Plasmas 16, 056118 (2009)], and the NEO drift-kinetic-equation solver [E. A. Belli and J. Candy, Plasma Phys. Controlled Fusion 54, 015015 (2012)] (for bootstrap current calculations) in order to generate equilibria with self-consistent pedestal structures as the plasma shape and various scalar parameters (e.g., normalized β, pedestal density, and edge safety factor [q₉₅]) are changed. These equilibria are then analyzed using automated M3D-C1 extended-magnetohydrodynamic modeling [S. C. Jardin et al., Comput. Sci. Discovery 5, 014002 (2012)] to compute the plasma response to three-dimensional magnetic perturbations. This workflow was created in conjunction with a DIII-D experiment examining the effect of triangularity on the 3D plasma response. Several versions of the workflow were developed, and the initial ones were used to help guide experimental planning (e.g., determining the plasma current necessary to maintain the constant edge safety factor in various shapes). Subsequentmore » validation with the experimental results was then used to revise the workflow, ultimately resulting in the complete model presented here. We show that quantitative agreement was achieved between the M3D-C1 plasma response calculated for equilibria generated by the final workflow and equilibria reconstructed from experimental data. A comparison of results from earlier workflows is used to show the importance of properly matching certain experimental parameters in the generated equilibria, including the normalized β, pedestal density, and q₉₅. On the other hand, the details of the pedestal current did not significantly impact the plasma response in these equilibria. A comparison to the experimentally measured plasma response shows mixed agreement, indicating that while the equilibria are predicted well, additional analysis tools may be needed. In conclusion, we note the implications that these results have for the success of future predict-first studies, particularly the need for scans of uncertain parameters and for close collaboration between experimentalists and theorists.« less

Authors:

Lyons, B. C.  ^[1];

• Search DOE PAGES for author "Lyons, B. C."
• Search DOE PAGES for ORCID "0000-0003-3232-1581"
• Search orcid.org for ORCID "0000-0003-3232-1581"

Paz-Soldan, C.  ^[1];

• Search DOE PAGES for author "Paz-Soldan, C."
• Search DOE PAGES for ORCID "0000-0001-5069-4934"
• Search orcid.org for ORCID "0000-0001-5069-4934"

Meneghini, O. ^[1]; Lao, L. L.  ^[1];

• Search DOE PAGES for author "Lao, L. L."
• Search DOE PAGES for ORCID "0000-0003-1937-2675"
• Search orcid.org for ORCID "0000-0003-1937-2675"

Weisberg, D. B. ^[1]; Belli, E. A.  ^[1];

• Search DOE PAGES for author "Belli, E. A."
• Search DOE PAGES for ORCID "0000-0001-7947-2841"
• Search orcid.org for ORCID "0000-0001-7947-2841"

Evans, T. E.  ^[1];

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

Ferraro, N. M.  ^[2];

• Search DOE PAGES for author "Ferraro, N. M."
• Search DOE PAGES for ORCID "0000-0002-6348-7827"
• Search orcid.org for ORCID "0000-0002-6348-7827"

Snyder, P. B. ^[1]

---

+ Show Author Affiliations

1. General Atomics, San Diego, CA (United States)
2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Publication Date:

2018-05-07

Research Org.:

General Atomics, San Diego, CA (United States)

Sponsoring Org.:

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

OSTI Identifier:

1436754

Alternate Identifier(s):

OSTI ID: 1436208

Grant/Contract Number:  

FG02-95ER54309; FC02-06ER54873; FC02-04ER54698; SC0015499

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 25; Journal Issue: 5; Journal ID: ISSN 1070-664X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma confinement; numerical modeling; tokamaks; magnetohydrodynamics; plasma instabilities