Title: Explaining the lack of power degradation of energy confinement in wide pedestal quiescent H-modes via transport modeling

Abstract

Wide pedestal quiescent H (WPQH)-mode is an attractive scenario for future burning plasmas as they operate without ELMs. WPQH is characterized by formation of a wider and higher pedestal (than quiescent H-mode), and broadband fluctuations in the pedestal. Unlike conventional H-modes, where the energy confinement time reduces with increasing heating power, the WPQH plasmas reported in this paper do not show power degradation of the energy confinement. As the injected neutral beam power was increased, reduced core (ρ ≤ 0.45) transport calculated by transp, as well as increased core temperatures, pressure gradient and diamagnetic E × B shear rate were observed. The reduction in the heat transport and rapid decrease in the ion temperature gradient scale length suggest the formation of an ion internal transport barrier (ITB) that was accompanied by increased stored energy in the core. Quasilinear turbulent transport modeling using the trapped gyro Landau fluid (tglf) code was used to predict the ITB and its turbulence stability properties. By using profiles and equilibria produced by matching the transp transport fluxes with the tglf transport model within the tgyro transport solver, the energy confinement time captures the experimentally observed insensitivity to the increased PNBI. Linear stability analysis reveals thatmore » drift-wave instabilities in the core are stabilized by E × B shear, T_i/T_e ratio and Shafranov shift; the latter was found to have the strongest effect on the turbulence suppression at the highest heating level.« less

Authors:

Houshmandyar, Saeid  ^[1];

• Search DOE PAGES for author "Houshmandyar, Saeid"
• Search DOE PAGES for ORCID "0000-0002-4738-3569"

Burrell, K. H.  ^[2];

• Search DOE PAGES for author "Burrell, K. H."
• Search DOE PAGES for ORCID "0000-0002-2639-1228"

Grierson, B. A.  ^[2];

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

McClenaghan, J.  ^[2];

• Search DOE PAGES for author "McClenaghan, J."
• Search DOE PAGES for ORCID "0000-0003-4735-0991"

Staebler, G. M.  ^[2];

• Search DOE PAGES for author "Staebler, G. M."
• Search DOE PAGES for ORCID "0000-0002-1944-1733"

Chrystal, C.  ^[2];

• Search DOE PAGES for author "Chrystal, C."
• Search DOE PAGES for ORCID "0000-0003-3049-8658"

Halfmoon, M. R.  ^[1];

• Search DOE PAGES for author "Halfmoon, M. R."
• Search DOE PAGES for ORCID "0000-0002-1815-3588"

Hatch, D. R.  ^[1];

• Search DOE PAGES for author "Hatch, D. R."
• Search DOE PAGES for ORCID "0000-0002-1625-4385"

Zeng, L. ^[3]; Austin, M. E.  ^[1]

• Search DOE PAGES for author "Austin, M. E."
• Search DOE PAGES for ORCID "0000-0002-0017-8605"

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+ Show Author Affiliations

1. Univ. of Texas, Austin, TX (United States)
2. General Atomics, San Diego, CA (United States)
3. Univ. of California, Los Angeles, CA (United States)

Publication Date:

Tue Mar 29 00:00:00 EDT 2022

Research Org.:

General Atomics, San Diego, CA (United States)

Sponsoring Org.:

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

OSTI Identifier:

1867203

Grant/Contract Number:  

FC02-04ER54698; FG02-97ER54415; SC0010500

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 62; Journal Issue: 5; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ELM-free; wide pedestal quiescent H mode; energy confinement time; transport modeling; TGLF