The enhanced pedestal H-mode in the National Spherical Torus experiment

Maingi, R.; Bell, R. E.; LeBlanc, B.P.; Gates, D.; Kaye, S. M.; Ménard, J.; Sabbagh, S. A.; Yuh, H.

doi:10.1016/j.jnucmat.2009.01.126

Cited by 9 publications

(11 citation statements)

References 14 publications

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“…Furthermore, the wider pedestals lead to high edge bootstrap currents, low inductive flux consumption, and correspondingly high noninductive fraction. While short EP H mode phases were observed [12] several years ago in NSTX, this Letter documents the first relatively long-lived EP H mode phases with durations up to 3 E , which raises the prospect of developing them as attractive targets for integrated scenarios in spherical tokamaks.…”

mentioning

confidence: 69%

Triggered Confinement Enhancement and Pedestal Expansion in High-Confinement-Mode Discharges in the National Spherical Torus Experiment

et al. 2010

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We report observation of a new high performance regime in discharges in the National Spherical Torus Experiment, where the H mode edge "pedestal" temperature doubles and the energy confinement increases by 50%. The spontaneous transition is triggered by a large edge-localized mode, either natural or externally triggered by 3D fields. The transport barrier grows inward from the edge, with a doubling of both the pedestal pressure width and the spatial extent of steep radial electric field shear. The dynamics suggest that 3D fields could be applied to reduce edge transport in fusion devices.

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mentioning

confidence: 69%

Triggered Confinement Enhancement and Pedestal Expansion in High-Confinement-Mode Discharges in the National Spherical Torus Experiment

et al. 2010

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“…The occurrence of these confinement transition increases at higher plasma current, or low q*. However, these low-q EPH scenarios are typically short lived, resulting in disruption soon after the confinement transition [155]. The exact cause of these disruptions in EPH modes is under investigation.…”

Section: : Disruption Causes At the Low-q* Boundarymentioning

confidence: 99%

Disruptions, Disruptivity, and Safer Operating Windows in the High-β Spherical Torus NSTX

Gerhardt¹,

Diallo²,

Gates³

et al. 2012

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“…Another ELM-free operational regime discussed in the literature is EP H-mode, observed in NSTX [115] but not yet reproduced on other devices. In this scenario, an ELM typically provides a trigger for a confinement bifurcation in which the pedestal T e and T i increase substantially, while the rate of line-average density ramping slows substantially or is arrested.…”

Section: Ep H-modementioning

confidence: 92%

“…In this section we discuss progress on research on the I-mode [19,[104][105][106][107][108][109], the quiescent H-mode [15,83,[110][111][112][113][114], and the Enhanced Pedestal (EP) H-mode [115][116][117]. Another candidate regime, Enhanced D α (EDA) H-mode [21,118], is discussed briefly in section 6 as studies [ 119] have shown that small ELMs appear in EDA H-mode at sufficiently high β.…”

Section: Naturally Occurring Quiescent Regimesmentioning

confidence: 99%

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Eroshenko¹

2013

Phys.-Usp.

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Large edge localized modes (ELMs) typically accompany good H-mode confinement in fusion devices, but can present problems for plasma facing components because of high transient heat loads. Here the range of techniques for ELM control deployed in fusion devices is reviewed. Two strategies in the ITER baseline design are emphasized: rapid ELM triggering and peak heat flux control via pellet injection, and the use of magnetic perturbations to suppress or mitigate ELMs. While both of these techniques are moderately well developed, with reasonable physical bases for projecting to ITER, differing observations between multiple devices are also discussed to highlight the needed community R&D. In addition, recent progress in ELM-free regimes, namely quiescent H-mode, I-mode, and enhanced pedestal H-mode is reviewed, and open questions for extrapolability are discussed. Finally progress and outstanding issues in alternate ELM control techniques are reviewed: supersonic molecular beam injection, edge electron cyclotron heating, lower hybrid heating and/or current drive, controlled periodic jogs of the vertical centroid position, ELM pace-making via periodic magnetic perturbations, ELM elimination with lithium wall conditioning, and naturally occurring small ELM regimes.

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The enhanced pedestal H-mode in the National Spherical Torus experiment

Cited by 9 publications

References 14 publications

Triggered Confinement Enhancement and Pedestal Expansion in High-Confinement-Mode Discharges in the National Spherical Torus Experiment

Triggered Confinement Enhancement and Pedestal Expansion in High-Confinement-Mode Discharges in the National Spherical Torus Experiment

Disruptions, Disruptivity, and Safer Operating Windows in the High-β Spherical Torus NSTX

Physics news on the Internet (based on electronic preprints)

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