Title: Compatibility of internal transport barrier with steady-state operation in the high bootstrap fraction regime on DIII-D

Abstract

Recent EAST/DIII-D joint experiments on the high poloidal beta tokamak regime in DIII-D have demonstrated fully noninductive operation with an internal transport barrier (ITB) at large minor radius, at normalized fusion performance increased by ≥30% relative to earlier work. The advancement was enabled by improved understanding of the 'relaxation oscillations', previously attributed to repetitive ITB collapses, and of the fast ion behavior in this regime. It was found that the 'relaxation oscillations' are coupled core-edge modes amenable to wall-stabilization, and that fast ion losses which previously dictated a large plasma-wall separation to avoid wall over-heating, can be reduced to classical levels with sufficient plasma density. By using optimized waveforms of the plasma-wall separation and plasma density, fully noninductive plasmas have been sustained for long durations with excellent energy confinement quality, bootstrap fraction ≥80%, $${{\beta}_{\text{N}}}\leqslant 4$$ , $${{\beta}_{\text{P}}}\geqslant 3$$ , and $${{\beta}_{\text{T}}}\geqslant 2\%$$ . Furthermore, these results bolster the applicability of the high poloidal beta tokamak regime toward the realization of a steady-state fusion reactor.

Authors:

Garofalo, Andrea M. ^[1]; Gong, Xianzu ^[2]; Grierson, Brian A. ^[3]; Ren, Qilong ^[2]; Solomon, Wayne M. ^[3]; Strait, Edward J. ^[1]; Van Zeeland, Michael A. ^[1]; Holcomb, Christopher T. ^[4]; Meneghini, Orso ^[1]; Smith, Sterling P. ^[1]; Staebler, Gary M. ^[1]; Wan, Baonian ^[2]; Bravenec, Ronald ^[5]; Budny, Robert V. ^[3]; Ding, Siye ^[2]; Hanson, Jeremy M. ^[6]; Heidbrink, William W. ^[7]; Lao, Lang L. ^[1]; Li, Guoqiang ^[2]; Pan, Chengkang ^[2] more »; Petty, Craig C. ^[1]; Qian, Jingping ^[2]; Paz-Soldan, Carlos ^[1]; Xu, Guosheng ^[2] « less

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+ Show Author Affiliations

1. General Atomics, San Diego, CA (United States)
2. Institute of Plasma Physics Chines Academy of Sciences, Anhui (People's Republic of China)
3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
5. Fourth State Research, Austin, TX (United States)
6. Columbia Univ., New York, NY (United States)
7. Univ. of California, Irvine, CA (United States)

Publication Date:

Mon Nov 16 00:00:00 EST 2015

Research Org.:

General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE Advanced Research Projects Agency - Energy (ARPA-E)

OSTI Identifier:

1353118

Alternate Identifier(s):

OSTI ID: 1238811; OSTI ID: 1438700

Report Number(s):

LLNL-JRNL-741496
Journal ID: ISSN 0029-5515

Grant/Contract Number:  

FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; FG02-04ER54761; SC-G903402

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 55; Journal Issue: 12; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY; steady state; ion transport barrier; wall stabilization; high beta; 70 PLASMA PHYSICS AND FUSION