The conditioning procedures in Tore Supra after CIEL implementation

Bucalossi, J.; Brosset, C.; Garnier, D.; Grisolia, Christian; Grosman, A.; Martín, G.; Laurent, François

doi:10.1016/s0022-3115(02)01339-9

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…Wall conditioning is essential in fusion machines to achieve a high plasma performance and reliable operational domain. The three conditioning techniques used in WEST are baking up to 200 • C, glow discharge conditioning (GDC) [32] using deuterium or helium, and boron wall coating through GDC of diborane, called boronization. Baking is generally performed before the campaign begins.…”

Section: Effect Of Wall Conditioning On Emissivitymentioning

confidence: 99%

Overview of the emissivity measurements performed in WEST: in situ and post-mortem observations

Gaspar¹,

Corre²,

Rigollet³

et al. 2022

Nucl. Fusion

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This paper summarizes the emissivity measurements performed on the plasma facing units (PFU) of the WEST lower divertor during the first phase of WEST running with a mix of actively cooled ITER-like PFUs made of bulk tungsten and inertially cooled PFUs made of graphite with a coating of tungsten. In-situ assessment of the emissivity and laboratory measurements after removing the W-coated graphite and ITER-grade PFUs from the WEST device are shown. The measurements exhibit a complex pattern with strong emissivity variation as function of space and time mainly explained with the variation of magnetic equilibrium (strike point location) as well as the plasma performances during the experimental campaigns. The exposed ITER-grade PFU exhibits sharp spatial variation of the emissivity from 0.05 to 0.85 at a monoblock scale (12mm) at the transition of the erosion (strike point location) and deposition (next to the strike point location) areas on the high field side. In the low field side, the emissivity varies from 0.12, at the strike point location, to 0.2 few cm away in the low field side direction. This emissivity range after exposure is much higher than the emissivity variation of unexposed PFU with emissivity from 0.09 to 0.15. In-situ observation performed on the W-coated graphite PFU shows a rapid evolution, typically few pulses, of the emissivity in the inner and outer strike point location. The whole spatial distribution is discussed as well as his variation due to the plasma operation from the start-up of WEST to the removal of the tungsten (W) coated graphite components.

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Section: Effect Of Wall Conditioning On Emissivitymentioning

confidence: 99%

Overview of the emissivity measurements performed in WEST: in situ and post-mortem observations

Gaspar¹,

Corre²,

Rigollet³

et al. 2022

Nucl. Fusion

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“…4.2.1. Tritium loading During operations of tokamaks like Tore Supra, ASEDX-Upgrade or JET, the background pressure is in the range of 10 −5 -10 −6 Pa [27,28,29,30]. At the end of the plasma, as the hydrogen isotopes recombines (and possibly desorbs from the wall), the pressure of hydrogen isotopes molecules increases and can reach few Pa.…”

Section: Toward Tokamak Conditionsmentioning

confidence: 99%

Modelling tritium adsorption and desorption from tungsten dust particles with a surface kinetic model

et al. 2021

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A kinetic surface model is presented and used to explain the loading and desorption kinetics of tritium retained in micrometre-sized tungsten (W) dust particles. The model describes the sticking of hydrogen isotopes from the gas phase to W surfaces and the desorption from W surfaces. The initial sticking coefficient is set to one and independent of the temperature. The activation energy for desorption depends on the hydrogen coverage of the surface and is parametrised with density functional theory (DFT) calculations for W(100), W(110) and W(111) surfaces. The DFT-parametrised model is successfully compared to experimental results showing that the amount of measured tritium as well as the desorption kinetic can be modelled with only tritium adsorbed on the surface of W dust particles. Then, the model is used to explore possible scenarios to remove the tritium from the W surfaces by exposing the tritiated surfaces to either deuterium and hydrogen. The simulations suggest that it can be possible to remove all the tritium trapped on the W surfaces even at room temperature as soon as the hydrogen or deuterium pressure is higher than the tritium pressure. This gives opportunity to build tritium removal scenarios for ITER.

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“…Wall fuel desaturation is especially mandatory in machines containing low Z elements such as carbon in the plasma facing components, since they can adsorb large quantities of hydrogenic species and desorb it in an uncontrolled way. In today's machines, helium glow discharges are used to generate fuel desaturation discharges [32,33]: energetic helium ions of typically 0.5-1 keV energy penetrate deeply into the subsurface layer, breaking the chemical hydrogen bonds. The free atomic hydrogen recombines to form molecular hydrogen within the subsurface and diffuses to the surface, where it desorbs and can finally be pumped out.…”

Section: Objectives Of First Wall Conditioning Discharges For Future ...mentioning

confidence: 99%

Review of radio frequency conditioning discharges with magnetic fields in superconducting fusion reactors

Cal¹,

Gauthier²

2005

Plasma Phys. Control. Fusion

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Wall conditioning techniques based on radio frequency (RF) discharges in fusion devices with permanent magnetic field were developed a few years ago. The first experiments of RF plasma discharges in the ion cyclotron frequency range called ion cyclotron conditioning were performed in Tore Supra and Textor and later also in HT-7 and W7-AS. A high conditioning efficiency in terms of hydrogen removal and surface cleaning has been demonstrated. The other alternative, RF conditioning discharges in the electron cyclotron range of frequencies and called electron cyclotron conditioning, has also been studied in the recent past. Besides surface hydrogen removal and surface cleaning, RF discharges have also been applied to thin film deposition. We report in this paper the main results obtained with several fusion devices on RF conditioning discharges and present conclusions for future devices such as ITER.

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The conditioning procedures in Tore Supra after CIEL implementation

Cited by 8 publications

References 3 publications

Overview of the emissivity measurements performed in WEST: in situ and post-mortem observations

Overview of the emissivity measurements performed in WEST: in situ and post-mortem observations

Modelling tritium adsorption and desorption from tungsten dust particles with a surface kinetic model

Review of radio frequency conditioning discharges with magnetic fields in superconducting fusion reactors

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