Title: Nonlinear two-fluid modeling of plasma response to RMPs for the ELM control in the ITER baseline

Abstract

Numerical modeling, combining the toroidal ideal MHD code GPEC and the nonlinear two-fluid MHD code TM1, was used for comprehensive studies of the plasma response to resonant magnetic perturbations (RMPs) with toroidal mode number n = 1–5 for controlling edge-localized modes (ELMs) in ITER for the standard operation scenario (15 MA Q = 10). Several issues related to RMP ELM control are investigated, including the optimization of the RMP coils configuration, the evaluation of the magnitude of density pump-out and the q95 windows of ELM suppression. GPEC calculates the magnetic response, which consistently includes the very important edge kink/peeling response to static magnetic perturbations. Furthermore, GPEC two-dimensional scans of the relative coil current phasing among the three rows of internal coils, at fixed coil current amplitude, reveal the optimal phasing for the RMP coil configuration with n = 1–5, respectively. The poloidal half wavelength of resonant mode at the edge of plasma calculated by GPEC indicates that the midplane row coils have the best resonant coupling with the plasma for n = 2, while the upper and lower row coils have the best resonant coupling with the plasma for n = 3. Based on the plasma kinetic equilibrium and the GPEC calculations of the magnetic response, TM1 was used to simulate the conditions for RMP field penetration in the ITER pedestal. TM1 shows magnetic island formation at the foot of ITER pedestal with RMP coil current threshold ranging from 4 kAt to 8 kAt with n = 2 to 4. These magnetic islands at the pedestal-foot lead to density pump-out, the magnitude of which scales as $${I}_{\text{RMP}}^{0.5}$$ and ranges from 5% to 20% at the pedestal-top when scanning the coil current from 4 to 60 kAt. The density pump-out is found to be weaker for higher n RMP. The nonlinear TM1 simulations also show field penetration at the pedestal-top, where the threshold of RMP coil current depends on the q₉₅. The alignment of the magnetic island and the location of the pedestal-top decreases the height and width of the pedestal to suppress ELMs. Simulations by two-dimensional scans of RMP coil current and q₉₅ reveal the accessible q₉₅ windows of ELM suppression for both n = 3 and 4 RMPs. The predicted q₉₅ windows of ELM suppression are very similar to the ones in currently operating tokamaks and the required RMP coil current for ELM suppression is less than 40–50 kAt, which is well within the designed capability for ITER. In addition, the simulations indicate that wide q₉₅ windows of ELM suppression may be accessible in ITER by operating with dominant n = 4 (or n = 5) RMPs.

Authors:

Hu, Q. M.  ^[1];

• Search DOE PAGES for author "Hu, Q. M."
• Search DOE PAGES for ORCID "0000-0002-8877-4988"

Park, J. -K.  ^[1];

• Search DOE PAGES for author "Park, J. -K."
• Search DOE PAGES for ORCID "0000-0003-2419-8667"

Logan, N. C.  ^[2];

• Search DOE PAGES for author "Logan, N. C."
• Search DOE PAGES for ORCID "0000-0002-3268-7359"

Yang, S. M.  ^[1];

• Search DOE PAGES for author "Yang, S. M."
• Search DOE PAGES for ORCID "0000-0003-1214-1268"

Grierson, B. A.  ^[1];

• Search DOE PAGES for author "Grierson, B. A."
• Search DOE PAGES for ORCID "0000-0001-5918-6506"

Nazikian, R.  ^[1];

• Search DOE PAGES for author "Nazikian, R."
• Search DOE PAGES for ORCID "0000-0001-6235-6692"

Yu, Q.  ^[3]

• Search DOE PAGES for author "Yu, Q."
• Search DOE PAGES for ORCID "0000-0003-2722-4445"

---

+ Show Author Affiliations

1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Max Planck Inst. für Plasmaphysik, Garching (Germany)

Publication Date:

Thu Sep 02 00:00:00 EDT 2021

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

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

OSTI Identifier:

1819034

Alternate Identifier(s):

OSTI ID: 1818861

Report Number(s):

LLNL-JRNL-825751
Journal ID: ISSN 0029-5515; 1039991; TRN: US2214052

Grant/Contract Number:  

AC52-07NA27344; AC02-09CH11466; FC02-04ER54698

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 61; Journal Issue: 10; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; resonant magnetic perturbations; density pump-out; ELMs suppression