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

Lipschultz, B.; Terry, J.; Boswell, C.; Goetz, J. A.; Hubbard, A.; Krasheninnikov, S. I.; LaBombard, B.; Pappas, Dimitri; Pitcher, C. S.; Wising, F.; Wukitch, S.

doi:10.1063/1.873448

Cited by 52 publications

(117 citation statements)

References 40 publications

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“…This is seen on Alcator C-Mod. [6,7] The distribution of the D γ emission does not agree with the possibility of perpendicular diffusion being the dominant mechanism fueling the PFZ. If diffusion was the main cause of particle flux into the PFZ one would expect the particle flux to increase when the divertor detachment is extended to the x-point due to the large perpendicular density gradient formed on the outer leg.…”

Section: Qualitative Analysismentioning

confidence: 86%

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Observations of cold, high density plasma in the private flux region of the Alcator C-Mod divertor

Boswell

Terry

LaBombard

et al. 2001

Journal of Nuclear Materials

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Significant plasma density has been observed in the private flux zone of the Alcator C-Mod tokamak. The behavior of the D γ emission profiles is consistent with the source of the plasma being due to an E× B drift generated by a poloidal temperature gradient. The plasma flux due to this drift is derived and evaluated. A plasma flux into the private flux zone is inferred by measurements of volumetric recombination using a tangentially viewing CCD camera and several spectroscopic views observing the high n-lines of the D o Balmer series. For the case of an attached divertor the inferred plasma flux to the PFZ has a linear scaling with respect to plasma pressure, as is expected from the temperature-gradient-induced, E × B drift.

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Section: Qualitative Analysismentioning

confidence: 86%

“…D γ emission along with other spectroscopic data are used to measure the volumetric recombination. [3][4][5][6][7] 2 Diagnostics Three diagnostics were used to obtain the information used in the analysis of the PFZ plasma. The first diagnostic is a set of flush-mounted Langmuir probes on the outer and inner divertor plates.…”

Section: Introductionmentioning

confidence: 99%

Observations of cold, high density plasma in the private flux region of the Alcator C-Mod divertor

Boswell

Terry

LaBombard

et al. 2001

Journal of Nuclear Materials

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“…This is verified by the time behavior of the principal VUV line intensities (O, N, D) for a spectrograph viewing chord passing through the upper edge of the x-point MARFE 29,30 . The sequential peaking and drop of successively lower-energy charge states of N and D imply that the local T e is dropping precipitously from ~ 50-70 eV -> ~5 eV.…”

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confidence: 91%

Divertor Physics Research on Alcator C-Mod

Lipschultz

LaBombard

Terry

et al. 2007

Fusion Science and Technology

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“…3-body recombination has been shown in some cases to account for large fractions (> 50%) of the ion sink in the divertor [260,206] and in the MARFE [261]. However, in some detached plasmas [206,260,262,263], in particular those with high SOL heat flux which detach after impurity puffing [260], recombination appears not to be a significant ion sink. This variation in recombination is due to the strong dependence of 3-body recombination on the local plasma density (n e 3 ).…”

Section: The Role Of Recombination In Divertor Processesmentioning

confidence: 99%

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

Cited by 52 publications

References 40 publications

Observations of cold, high density plasma in the private flux region of the Alcator C-Mod divertor

Observations of cold, high density plasma in the private flux region of the Alcator C-Mod divertor

Divertor Physics Research on Alcator C-Mod

Chapter 4: Power and particle control

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