The role of friction in SOL pressure balance in Alcator C-Mod

Pitcher, C.S.; Goetz, J. A.; LaBombard, B.; Lipschultz, B.; Weaver, James L.; Welch, B.

doi:10.1016/s0022-3115(98)00850-2

Cited by 16 publications

(14 citation statements)

References 9 publications

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“…Even in Ohmic discharges, where recombination is at its highest, a calculation of the recombination-related momentum loss leads to pressure decreases that are a fraction (~5%) of that observed. More generally, the quantitative measurements of recombination shown here and elsewhere [50][51] , experimentally verify that high levels of recombination are not a necessary condition for divertor detachment.…”

Section: Inferred Ion Source Changessupporting

confidence: 72%

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The role of particle sinks and sources in Alcator C-Mod detached divertor discharges

et al. 1999

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Detailed measurements of the magnitude and location of volumetric recombination occurring in the detached divertor of Alcator C-Mod tokamak [I.H. Hutchinson et al., Phys. Plasmas 1, 1511(1994] are presented. The drop in divertor plate ion current during detachment is due to two mechanisms: (1) volumetric recombination in the divertor plasma; and (2) reductions in the divertor ion source. Depending on plasma conditions, each of these can be the primary mechanism for the observed ion current reduction in detachment. The ion source during detachment is inferred and its magnitude is consistent with the measured divertor power flow. A scaling of the density in the divertor recombining region for L-(Low confinement) mode plasmas is found, n e,r ∝ n e 0.8 • P SOL 2/7 . A model based on pressure variation along a flux surface during detachment is consistent with the main features of this scaling.

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Section: Inferred Ion Source Changessupporting

confidence: 72%

“…Ref. 50) show that recombination does not play an important role as a momentum sink. This has been verified by experimentally-derived estimates of both the ion-neutral collision and recombination momentum sinks in the same discharge [50][51] , at least in these types of discharges.…”

Section: Inferred Ion Source Changesmentioning

confidence: 99%

The role of particle sinks and sources in Alcator C-Mod detached divertor discharges

et al. 1999

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“…The implication was that the neutrals were moving at close to the background plasma flow velocity (sound speed at the plate) and thus did not remove as much momentum as stationary neutrals could. Later flow measurements appeared to confirm this 28 .…”

Section: General Detachment Characteristicsmentioning

confidence: 75%

Divertor Physics Research on Alcator C-Mod

Lipschultz

LaBombard

Terry

et al. 2007

Fusion Science and Technology

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108

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“…Spectroscopic measurements of parallel flow velocities of low charge state impurity ions (CII, CIII, BII, HeII) is another alternative flow measurement [119,120]. Such measurements are roughly consistent with expectations for flow patterns in the divertor but direct comparisons with probes have not been made.…”

Section: Sol Flow and Classical Drifts Effectsmentioning

confidence: 83%

Chapter 4: Power and particle control

Divertor¹,

Database²,

Editors³

1999

Nucl. Fusion

280

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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The role of friction in SOL pressure balance in Alcator C-Mod

Cited by 16 publications

References 9 publications

The role of particle sinks and sources in Alcator C-Mod detached divertor discharges

The role of particle sinks and sources in Alcator C-Mod detached divertor discharges

Divertor Physics Research on Alcator C-Mod

Chapter 4: Power and particle control

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