Dissipative divertor operation in the Alcator C-Mod tokamak

Lipschultz, B.; Goetz, J. A.; LaBombard, B.; McCracken, G.M.; Terry, J. L.; Graf, M.; Granetz, R.; Jablonski, D.; Kurz, Christian; Niemczewski, A.; Snipes, J. A.

doi:10.1016/0022-3115(94)00446-3

Cited by 71 publications

(33 citation statements)

References 18 publications

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“…Reduction of the heat flux density on plasma facing components to a technically feasible level is one of the most challenging issues for magnetic confinement fusion devices on the path to a reactor. A promising approach is the creation of a controlled impurity radiation zone in the vicinity of the plasma-surface-interaction (PSI) area by means of a divertor [1][2][3][4][5][6][7][8]. The basic idea of a divertor configuration [9][10][11] is to separate the PSI region from the plasma confinement region by establishing an appropriate separatrix-bounded magnetic configuration.…”

mentioning

confidence: 99%

First Observation of a Stable Highly Dissipative Divertor Plasma Regime on the Wendelstein 7-X Stellarator

et al. 2019

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mentioning

confidence: 99%

First Observation of a Stable Highly Dissipative Divertor Plasma Regime on the Wendelstein 7-X Stellarator

et al. 2019

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“…[75] but was not studied extensively until the early 1990's [75,72,[76][77][78][79][80][81]. Detachment does not occur on all flux surfaces simultaneously, but begins near the separatrix and extends radially outward into the SOL as the density is raised [82,46].…”

Section: Divertor Detachmentmentioning

confidence: 99%

“…JT60-U saw detachment at similar densities, roughly 0.7-0.75n G but almost independent of power in this case. In its standard configuration, Alcator C-Mod, reported detachment in the range 0.3-0.4n G with a nearly linear dependence on input power [77]. However, divertor geometry was found to have an important influence on the detachment threshold in C-Mod, with flat-plate divertor configurations detaching at densities 50-80% above the levels found for the standard inclined-plate geometry [87].…”

Section: Divertor Detachmentmentioning

confidence: 99%

Density limits in toroidal plasmas

Greenwald

2002

Plasma Phys. Control. Fusion

456

477

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In addition to the operational limits imposed by MHD stability on plasma current and pressure, an independent limit on plasma density is observed in confined toroidal plasmas. This review attempts to summarize recent work on the phenomenology and physics of the density limit. Perhaps the most surprising result is that all of the toroidal confinement devices considered operate in similar ranges of (suitably normalized) densities. The empirical scalings derived independently for tokamaks and reversed field pinches (RFP) are essentially identical, while stellarators appear to operate at somewhat higher densities with a different scaling. Dedicated density limit experiments have not been carried out for spheromaks and field-reversed configurations (FRC), however "optimized" discharges in these devices are also well characterized by the same empirical law. In tokamaks, where the most extensive studies have been conducted, there is strong evidence linking the limit to physics near the plasma boundary thus it is possible to extend the operational range for line-averaged density by operating with peaked density profiles. Additional particles in the plasma core apparently have no effect on density limit physics. While there is no widely accepted, first principles model for the density limit, research in this area has focussed on mechanisms which lead to strong edge cooling. Theoretical work has concentrated on the consequences of increased impurity radiation which may dominate power balance at high densities and low temperatures. These theories are not entirely satisfactory as they require assumptions about edge transport and make predictions for power and impurity scaling that may not be consistent with experimental results. A separate thread of research looks for the cause in collisionality enhanced turbulent transport. While there is experimental and theoretical support for this approach, understanding of the underlying mechanisms is only at a rudimentary stage and no predictive capability is yet available..

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“…These characteristic properties have been previously observed in tokamak PDD discharges [10][11][12]. The PDD regime was established transiently by puffing D 2 in the divertor region at a high gas injection rate (1.1-2.8) · 10 22 s À1 .…”

Section: Partially Detached Divertor Regimementioning

confidence: 80%