Pellet fuelling, ELM pacing and disruption mitigation technology development for ITER

Baylor, L. R.; Combs, S. K.; Foust, C. R.; Jernigan, T.C.; Meitner, S. J.; Parks, P.B.; Caughman, J. B. O.; Fehling, D. T.; Maruyama, S.; Qualls, A. L.; Rasmussen, D. A.; Thomas, C. E.

doi:10.1088/0029-5515/49/8/085013

Cited by 67 publications

(49 citation statements)

References 21 publications

(27 reference statements)

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“…23 In these experiments, a single large ͑D ϳ 1.3 cm͒ frozen deuterium pellet is fired into the vacuum chamber. At the first wall, the pellet is shattered by a v-groove which directs the resulting mixture of deuterium ice shards and liquid toward the plasma core.…”

Section: B Shattered Pellet Injectionmentioning

confidence: 99%

Experiments in DIII-D toward achieving rapid shutdown with runaway electron suppression

et al. 2010

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Experiments have been performed in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] toward understanding runaway electron formation and amplification during rapid discharge shutdown, as well as toward achieving complete collisional suppression of these runaway electrons via massive delivery of impurities. Runaway acceleration and amplification appear to be well explained using the zero-dimensional (0D) current quench toroidal electric field. 0D or even one-dimensional modeling using a Dreicer seed term, however, appears to be too small to explain the initial runaway seed formation. Up to 15% of the line-average electron density required for complete runaway suppression has been achieved in the middle of the current quench using optimized massive gas injection with multiple small gas valves firing simultaneously. The novel rapid shutdown techniques of massive shattered pellet injection and shell pellet injection have been demonstrated for the first time. Experiments using external magnetic perturbations to deconfine runaways have shown promising preliminary results.

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Section: B Shattered Pellet Injectionmentioning

confidence: 99%

Experiments in DIII-D toward achieving rapid shutdown with runaway electron suppression

et al. 2010

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“…For the ITER design, the fuelling efficiency of MGI and its scaling are of importance. It is to be mentioned that a novel shattered pellet technique significantly improves the number of atoms delivered by a pellet [9][10][11], the scalability of this technique is also under investigation.…”

Section: Introductionmentioning

confidence: 99%

Fuelling efficiency of massive gas injection in TEXTOR: mass scaling and importance of gas flow dynamics

et al. 2011

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Abstract.Fuelling efficiency is an important parameter in designing a massive gas injection system for suppression of runaway electrons in ITER. In this work a Z-dependence of the fuelling efficiency is measured for TEXTOR. The dependence covers the following gases: He, Ne, Ar, Kr, Xe and a 10% Ar-D 2 mixture. It is shown that the fuelling efficiency significantly decreases with the gas mass, from above 0.5 for He to below 0.03 for Xe.To explain the variation of the efficiency with the gas mass and pressure a simple model of the gas flow from the valve to the plasma edge is developed. The flow model is validated by using available laboratory flow measurements of a TEXTOR-similar injection system. The unsteady gas flow and a premature plasma disrupting are shown to explain the mass dependence of the efficiency.

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“…Extension of this method to larger size pellets to maximize the particle assimilation into the plasma has been proposed and tested in the laboratory [15]. A new large pellet device has been built at ORNL to test the capability of very large shattered pellets to mitigate disruptions and prevent runaway-electron damage [13].…”

Section: Dm Technologymentioning

confidence: 99%

Disruption-Mitigation-Technology Concepts and Implications for ITER

Baylor

Jernigan

Combs

et al. 2010

IEEE Trans. Plasma Sci.

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Disruptions on ITER present challenges to handle the intense heat flux, the large forces from halo currents, and the potential first wall damage from energetic runaway electrons. Injecting large quantities of material into the plasma during the disruption can reduce the plasma energy and increase its resistivity to mitigate these effects. Assessments of the amount of various mixtures and quantities of the material required have been made to provide collision mitigation of runaway-electron conversion, which is the most difficult challenge. The quantities of the material required (∼ 0.5 MPa · m 3 for deuterium or helium gas) are large enough to have implications on the design and operation of the vacuum system and tokamak exhaust processing system.

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Pellet fuelling, ELM pacing and disruption mitigation technology development for ITER

Cited by 67 publications

References 21 publications

Experiments in DIII-D toward achieving rapid shutdown with runaway electron suppression

Experiments in DIII-D toward achieving rapid shutdown with runaway electron suppression

Fuelling efficiency of massive gas injection in TEXTOR: mass scaling and importance of gas flow dynamics

Disruption-Mitigation-Technology Concepts and Implications for ITER

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