Mitigation of Tokamak Disruptions Using High-Pressure Gas Injection

Whyte, D.G.; Jernigan, T. C.; Humphreys, D. A.; Hyatt, A.W.; Lasnier, C.J.; Parks, P.B.; Evans, T.E.; Rosenbluth, M. N.; Taylor, P. L.; Kellman, A.G.; Gray, D.S.; Hollmann, E. M.; Combs, S. K.

doi:10.1103/physrevlett.89.055001

Cited by 131 publications

(73 citation statements)

References 8 publications

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“…After the thermal quench, the plasma temperature, and hence resistivity and CQ rate, are determined primarily by the the ionization energy of the injected gas. This is because the plasma is in equilibrium between ohmic heating and line radiation [3]. This can be seen in figure 1(c).…”

Section: Resistive Terminationmentioning

confidence: 52%

“…Massive gas injections also have the potential to prevent runaway electron formation by creating a strong collisional drag force [3], induced MHD stochasticity [4,5], and strong bremsstrahlung and synchrotron radiation drag [6]. Noble gas species are used because they have low chemical reactivity with in-vessel components, which are often at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

et al. 2011

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Abstract. Mixed gases are used for massive gas injection disruption mitigation on Alcator C-Mod in order to optimize radiation efficiency, halo current reduction, and response time. Gas mixtures of helium and argon (argon fraction 0-50%) are investigated in detail, as well as mixtures of deuterium, argon, krypton, and helium. Experiments show that injecting He/Ar mixtures leads to faster thermal and current quenches than with pure helium or argon injection, thus improving the time response of the disruption mitigation system and reducing the halo current. Small fractions of argon (∼5-10%) in helium also lead to optimized radiation fractions with large electron density increases in the core plasma. These results are consistent with the expectation that small fractions of argon will be entrained with the faster helium in the early phases of gas flow. The gas mixing allows one to simultaneously exploit the fast particle delivery rate of light helium gas and the large radiation capability of argon.

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Section: Resistive Terminationmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

et al. 2011

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“…In contrast, mitigated disruptions [40] would lead to tolerable wall loads and can even have a positive affect on the release of trapped fuel from the wall [41]. Therefore, mitigated disruptions are discussed as a routine discharge termination procedure in ITER [2].…”

Section: Erosion Induced By Disruptionsmentioning

confidence: 99%

Dynamics of erosion and deposition in tokamaks

Kreter

Brezinsek

Coad

et al. 2009

Journal of Nuclear Materials

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In recent years, a general qualitative understanding has been reached about the major pathways of material migration in divertor tokamaks. Main chamber wall components have been identified as the major source of material erosion. The eroded material is transported by scrape-off layer flows, in the case of the ion B×∇B drift pointing towards the X-point, predominately towards the inner divertor leg, where it is deposited in the form of amorphous layers. On JET, where carbon is the main plasma-facing material, it has been found that the presence of deposited carbon rich layers determines the dynamic characteristics of further redistribution of carbon, in particular towards remote areas. The transport from the strike point to the deposition location is mainly line-of-sight. The amount of eroded carbon depends on the surface type, with lower rates for the bare CFC and higher rates for deposited layers. The erosion rates in the inner divertor increase non-linearly with increasing ELM energies.

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“…Argon is an important species for TOKAMAK studies, being used as a gas to radiatively cool the divertor and as a potential means of mitigating plasma disruptions (Whyte et al 2002). In particular, Ar III lines have been shown to provide useful spectral diagnostics for astrophysical studies (Keenan & McCann 1990;Keenan & Conlon 1993).…”

Section: Introductionmentioning

confidence: 99%

Electron-impact excitation of Ar²⁺

Burgos

Loch

Ballance

et al. 2009

A&A

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Context. Emission from Ar III is seen in planetary nebulae, in H II regions, and from laboratory plasmas. The analysis of such spectra requires accurate electron impact excitation data. Aims. The aim of this work is to improve the electron impact excitation data available for Ar 2+ , for application in studies of planetary nebulae and laboratory plasma spectra. The effects of the new data on diagnostic line ratios are also studied. Methods. Electron-impact excitation collision strengths have been calculated using the R-Matrix Intermediate-Coupling FrameTransformation method and the R-Matrix Breit-Pauli method. Excitation cross sections are calculated between all levels of the configurations 3s 2 3p 4 , 3s3p 5 , 3p 6 , 3p 5 3d, and 3s 2 3p 3 nl (3d ≤ nl ≤ 5s). Maxwellian effective collision strengths are generated from the collision strength data. Results. Good agreement is found in the collision strengths calculated using the two R-Matrix methods. The collision strengths are compared with literature values for transitions within the 3s 2 3p 4 configuration. The new data has a small effect on T e values obtained from the I(λ7135 Å + λ7751 Å)/I(λ5192 Å) line ratio, and a larger effect on the N e values obtained from the I(λ7135 Å)/I(λ9 μm) line ratio. The final effective collision strength data is archived online .

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Mitigation of Tokamak Disruptions Using High-Pressure Gas Injection

Cited by 131 publications

References 8 publications

Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

Dynamics of erosion and deposition in tokamaks

Electron-impact excitation of Ar²⁺

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Mitigation of Tokamak Disruptions Using High-Pressure Gas Injection

Cited by 131 publications

References 8 publications

Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

Using mixed gases for massive gas injection disruption mitigation on Alcator C-Mod

Dynamics of erosion and deposition in tokamaks

Electron-impact excitation of Ar2+

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Electron-impact excitation of Ar²⁺