Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injection

Ferron, J. R.; Holcomb, C.T.; Luce, T. C.; Park, J. M.; Politzer, Peter; Turco, F.; Heidbrink, W. W.; Doyle, E. J.; Hanson, J.M.; Hyatt, A.W.; In, Y.; Haye, R. J. La; Lanctot, M. J.; Okabayashi, M.; Pétrie, T.W.; Petty, C. C.; Zeng, L.

doi:10.1063/1.4821072

Cited by 21 publications

(23 citation statements)

References 36 publications

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“…Only the high-' i scenario [48] achieves high b N without wall stabilization. The broad profiles of pressure and current density that are preferred for maximizing the bootstrap current are in addition favorable for wall stabilization, and DIII-D's off-axis neutral beam injection (a capability added in 2011) contributes to broadening of these profiles [40,50,100]. As shown by the blue data points in Fig.…”

Section: Stabilitymentioning

confidence: 94%

“…High-q min scenario discharges typically have q min = 1.4-2.3, with q 95 = 5-7 [39][40][41]. The current profile is also broad, but not as much as the High-b P scenario.…”

Section: Range Of Plasma Scenarios Exploredmentioning

confidence: 99%

“…The introduction of off-axis neutral beam injection led to improved capability to operate with broader current and pressure profiles to increase b N limits [40,41]. Discharges with 1.4 \ q min \ 2 and 5 \ q 95 \ 6.…”

Section: High Q Min Scenariomentioning

confidence: 99%

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DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

et al. 2018

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We review progress made on the advanced tokamak path to fusion energy by the DIII-D National Fusion Facility (Luxon et al. in Nucl Fusion 42:614, 2002). The advanced tokamak represents a highly attractive approach for a future steady state fusion power plant. In this concept, there is a natural alignment between high pressure operation, favorable stability and transport properties, and a highly self-driven ('bootstrap') plasma current to sustain operation efficiently and without disruptions. Research on DIII-D has identified several promising plasma configurations for fully non-inductive operation with potential applications to a range of future devices, from ITER to nuclear science facilities, to compact or large scale fusion power plants. Significant progress has been made toward realizing these scenarios, with the demonstration of high b access, off-axis current drive techniques, model based profile control, and stability and ELM control in reactor relevant physics regimes. Radiative techniques have also been pioneered to develop improved compatibility with divertor requirements, and simultaneous access to high performance pedestals. Research has also developed major advances in physics understanding, validating concepts of kinetic damping of ideal MHD instabilities that enable high b operation, identifying how current profile and b influence plasma turbulence in order to validate and improve turbulent transport models, and understanding the physics of energetic particle redistribution due to Alfvénic and other instabilities. These advances have been partnered with development of a rigorous integrated modeling framework used to interpret and validate individual physics models of the various aspects of plasma behavior, and to guide development of improved regimes and upgrades. These tools are also being used to develop and validate concepts for future reactors directly. Having established these foundations, DIII-D is now undergoing a substantial upgrade to raise power, current drive, electron heating and 3-D field capabilities in order to validate this physics and test conceptual solutions in reactor-relevant physics regimes, with a goal to resolve the key scientific and technology questions to enable a decision on a future steady state fusion power plant.

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Section: Stabilitymentioning

confidence: 94%

“…High-q min scenario discharges typically have q min = 1.4-2.3, with q 95 = 5-7 [39][40][41]. The current profile is also broad, but not as much as the High-b P scenario.…”

Section: Range Of Plasma Scenarios Exploredmentioning

confidence: 99%

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DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

et al. 2018

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“…H-mode is considered the reference scenario to produce a fusion power of 500 MW with a fusion gain Q = 10, implying a fusion power ten times higher than the input heating power, in the International Thermonuclear Experimental Reactor (ITER) 4 , which is the world's largest tokamak being built in France under a collaboration between China, the EU, India, Japan, the Republic of Korea, Russia, and the U.S.A. [5][6][7] . Various advanced tokamak operation modes such as hybrid mode 8,9 , high poloidal beta mode 10 , and high q min mode 11 are based on this H-mode. H-modes can satisfy the high con nement and avoid impurity accumulation for a long pulse duration 12,13 , but their large pressure gradient at the edge due to ETBs triggers a signi cant edge plasma instability, the so-called edge localised mode (ELM), which can severely damage the inner wall of the device 14,15 .…”

Section: Introductionmentioning

confidence: 99%

A sustained high-temperature fusion plasma regime facilitated by fast ions

Han

Park

Sung

et al. 2022

Nature

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We report a discovery of a fusion plasma regime suitable for commercial fusion reactor where the ion temperature was sustained above 100 million degree about 20 s for the rst time. Nuclear fusion as a promising technology for replacing carbon-dependent energy sources has currently many issues to be resolved to enable its large-scale use as a sustainable energy source. State-of-the-art fusion reactors cannot yet achieve the high levels of fusion performance, high temperature, and absence of instabilities required for steady-state operation for a long period of time on the order of hundreds of seconds. This is a pressing challenge within the eld, as the development of methods that would enable such capabilities is essential for the successful construction of commercial fusion reactor. Here, a new plasma con nement regime called fast ion roled enhancement (FIRE) mode is presented. This mode is realized at Korea Superconducting Tokamak Advanced Research (KSTAR) and subsequently characterized to show that it meets most of the requirements for fusion reactor commercialization. Through a comparison to other well-known plasma con nement regimes, the favourable properties of FIRE mode are further elucidated and concluded that the novelty lies in the high fraction of fast ions, which acts to stabilize turbulence and achieve steady-state operation for up to 20 s by self-organization. We propose this mode as a promising path towards commercial fusion reactors.

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“…In these plasmas, b N is usually limited to about 3 by the available power, and the normalized global energy confinement H 89P 14 is typically 1.6-1.8. 15 A "high-b P " regime developed for testing long-pulse operation on the EAST tokamak 16 has q min ¼ 3-5, q 95 ¼ 11-12, lineaveraged density ¼ 5-6:5 Â 10 19 m À3 , I P ¼ 0.6-0.65 MA, and Greenwald fraction near 1. b N is limited to about 4 by instability rather than by confinement, and H 89P ¼ 2-3.…”

Section: Introductionmentioning

confidence: 99%

Fast-ion transport in qmin>2, high-β steady-state scenarios on DIII-D

et al. 2015

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Results from experiments on DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] aimed at developing high b steady-state operating scenarios with high-q min confirm that fast-ion transport is a critical issue for advanced tokamak development using neutral beam injection current drive. In DIII-D, greater than 11 MW of neutral beam heating power is applied with the intent of maximizing b N and the noninductive current drive. However, in scenarios with q min > 2 that target the typical range of q 95 ¼ 5-7 used in next-step steady-state reactor models, Alfv en eigenmodes cause greater fast-ion transport than classical models predict. This enhanced transport reduces the absorbed neutral beam heating power and current drive and limits the achievable b N . In contrast, similar plasmas except with q min just above 1 have approximately classical fast-ion transport. Experiments that take q min > 3 plasmas to higher b P with q 95 ¼ 11-12 for testing long pulse operation exhibit regimes of better than expected thermal confinement. Compared to the standard high-q min scenario, the high b P cases have shorter slowing-down time and lower rb fast , and this reduces the drive for Alfv enic modes, yielding nearly classical fast-ion transport, high values of normalized confinement, b N , and noninductive current fraction. These results suggest DIII-D might obtain better performance in lower-q 95 , high-q min plasmas using broader neutral beam heating profiles and increased direct electron heating power to lower the drive for Alfv en eigenmodes. V C 2015 AIP Publishing LLC. [http://dx.

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Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injection

Cited by 21 publications

References 36 publications

DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

A sustained high-temperature fusion plasma regime facilitated by fast ions

Fast-ion transport in qmin>2, high-β steady-state scenarios on DIII-D

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Progress toward fully noninductive discharge operation in DIII-D using off-axis neutral beam injection

Cited by 21 publications

References 36 publications

DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

DIII-D Research to Prepare for Steady State Advanced Tokamak Power Plants

A sustained high-temperature fusion plasma regime facilitated by fast ions

Fast-ion transport in qmin&gt;2, high-β steady-state scenarios on DIII-D

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Fast-ion transport in qmin>2, high-β steady-state scenarios on DIII-D