Particle flux and temperature dependence of carbon impurity production from an inertially-cooled limiter in Tore Supra

Tobin, Stephen J; DeMichelis, C.; Hogan, J.; Monier‐Garbet, P.; Guilhem, D.

doi:10.1088/0741-3335/40/7/009

Cited by 7 publications

(3 citation statements)

References 22 publications

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“…The physically sputtered impurities are assumed to have a Thompson velocity distribution, whilst the chemically sputtered atoms are given an energy of 0.5 eV. The current available chemical sputtering data exhibit large uncertainties [6][7][8][9][10][11][12][13] and the atomic data for various hydrocarbon decomposition processes are poorly known. The actual break-up of CD 4 and other hydrocarbon products has not yet been modelled by the EDGE2D/NIMBUS code.…”

Section: Divertor Screeningmentioning

confidence: 99%

“…Both physical and chemical sputtering depend on the energy and the mass of the impinging species. In addition, chemical sputtering depends on surface temperature [6] and exhibits an uncertain flux dependence [7][8][9][10][11][12][13]. The divertor screening for the impurities relies on the large ion flow present in the divertor resulting from local flux amplification due to recycled neutrals, which drags impurities towards the divertor targets and opposes the thermal gradient force which tends to drive the impurity ions towards the main chamber [14,15].…”

Section: Introductionmentioning

confidence: 99%

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Effects of divertor geometry and chemical sputtering on impurity behaviour and plasma performance in JET

et al. 2000

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Abstract. The effects of increased geometrical closure on the behaviour of the recycling and intrinsic impurities are investigated in JET Mark I, Mark IIA and Mark IIGB pumped divertors. Increasing the divertor closure leads to a significant improvement in exhaust for both deuterium and recycling impurities. However, the impurity enrichment in the exhaust gases remains unchanged due to a simultaneous increase in deuterium and impurity compression in the divertor. A comparison is made for helium, neon and argon under different plasma conditions. In addition, the operation of the Mark II and Mark IIGB divertors has shown that Z eff is reduced with the improved divertor closure in the L mode discharges, although no obvious changes in the Z eff values have been observed in the ELMy H modes. The divertor target surface temperature has a strong influence on intrinsic carbon production. The carbon source in the Mark II and Mark IIGB divertors is significantly higher than that in the Mark I divertor, which is attributed to enhanced chemical sputtering at the increased divertor tile temperature of the Mark II and Mark IIGB divertors (related to the divertor cooling system), as opposed to the increased closure. The consequences of this elevated yield for plasmas under different operation conditions are discussed, and further evidence, obtained from a specific wall/divertor temperature reduction experiment, is presented. The effect of the divertor screening on the chemically produced impurities is investigated using the EDGE2D/NIMBUS/DIVIMP codes for the different recycling regimes and comparisons are made with experimental observations from the Mark I, Mark IIA and Mark IIAP divertors taking into account the change in chemical sputtering yield due to the different tile temperatures of these divertors.

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Section: Divertor Screeningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of divertor geometry and chemical sputtering on impurity behaviour and plasma performance in JET

et al. 2000

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“…4 In some cases, when inertially cooled limiters are used, radiation enhanced sublimation ͑above 1100°C͒ and eventually sublimation can occur. 5 Additional impurity sources are due to local particle acceleration near high frequency antennas. A time-dependent code has been developed, using realistic geometric and magnetic configurations to model the experiments.…”

Section: General Features Of the Actively Cooled Plasma Facing Commentioning

confidence: 99%

Physics and design interplay phenomena in an actively cooled tokamak: Tore Supra

Chatelier¹

2001

Physics of Plasmas

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In order to achieve long pulse high performance plasma discharges, actively cooled plasma facing components (PFCs) have been installed since the beginning of Tore Supra in 1988. So far, up to 280 MJ of energy could be removed within a single discharge of 2 mn duration. Active cooling creates a specific environment, like, e.g., constant low wall temperature (<200 °C) or the presence of water pipes close to the plasma boundary, as compared to inertially cooled devices. Physical processes, specific of the actively cooled environment occur, which may sometimes induce irreversible damage that would not even have been observed on conventional PFCs. After a short description of the development status of the actively cooled PFCs program at Tore Supra, the paper concentrates on those aspects where physics and design aspects are mixed, which deserve thorough analysis for the conception of a next step fusion device environment.

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Hydrogen Recycling in the RFX Reversed Field Pinch

Bettella¹,

Carraro²,

Puiatti³

et al. 2000

Hydrogen Recycling at Plasma Facing Materials

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Particle flux and temperature dependence of carbon impurity production from an inertially-cooled limiter in Tore Supra

Cited by 7 publications

References 22 publications

Effects of divertor geometry and chemical sputtering on impurity behaviour and plasma performance in JET

Effects of divertor geometry and chemical sputtering on impurity behaviour and plasma performance in JET

Physics and design interplay phenomena in an actively cooled tokamak: Tore Supra

Hydrogen Recycling in the RFX Reversed Field Pinch

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