Pellet fuelling and control of burning plasmas in ITER

Baylor, L. R.; Parks, P.B.; Jernigan, T. C.; Caughman, J. B. O.; Combs, S. K.; Foust, C. R.; Houlberg, W. A.; Maruyama, S.; Rasmussen, D. A.

doi:10.1088/0029-5515/47/5/008

Cited by 115 publications

(91 citation statements)

References 28 publications

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“…The latter can be utilized to advantage by optimizing the pellet injection location and it has been confirmed in tokamaks that the high field side pellet injection can improve effective pellet fueling performance [4,5]. The ∇B induced drift model is widely accepted as the mechanism of the pellet plasmoid drift toward the low magnetic field direction in tokamak devices [6][7][8], and the ITER plasma fueling system relies on the high field side pellet injection [9].…”

Section: Introductionmentioning

confidence: 99%

Observation of Cross-Field Transport of Pellet Plasmoid in LHD

Sakamoto

Yamada

2011

Plasma and Fusion Research

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A three-dimensional observation of the solid hydrogen pellet ablation has been performed by using a fast stereo imaging camera to investigate the pellet ablation dynamics. The initial velocity component of the injected pellet is maintained during ablation in a hot plasma, and the pellet penetrates to the core plasma. On the other hand, it has been observed that part of high density pellet plasmoid, which is formed around the pellet substance by ablating hydrogen pellet, intermittently breaks away from the pellet ablating position and the breakaway plasmoid is transported across a confinement field. The breakaway plasmoid recurrently develops at the rate of about 100 times per millisecond and it is non-diffusively transported approximately 0.1 m during its several 10 µs lifetime in the opposite direction to the pellet motion, namely, toward the low magnetic field side. This observation gives a reasonable explanation for the difference between the pellet ablation position and the effective particle deposition profile.

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Section: Introductionmentioning

confidence: 99%

Observation of Cross-Field Transport of Pellet Plasmoid in LHD

Sakamoto

Yamada

2011

Plasma and Fusion Research

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“…The maximum extrusion speed is 55 mm/s at 37.5 rpm of screw rotation for a 3 mmφ solid hydrogen rod, and this value corresponds to 34 mg/s and 40 Pa m 3 /s for H 2 in the other units. The extrusion speed is sufficient for fueling for LHD discharges, and it has already achieved 40% of ITER pellet fueling requirements [20,21]. When the extrusion speed becomes over speed, the solid hydrogen melts due to temperature rise and is abruptly dumped from the nozzle.…”

Section: Solid Hydrogen Extrusion With Screw Extrudermentioning

confidence: 99%

Development of Advanced Pellet Injector Systems for Plasma Fueling

Sakamoto

Yamada

2009

Plasma and Fusion Research

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Two types of solid hydrogen pellet injection systems have been developed, and plasma refueling experiments have been performed using these pellet injectors. One is an in-situ pipe-gun type pellet injector, which has the simplest design of all pellet injectors. This in-situ pipe-gun injector has 10 injection barrels, each of which can independently inject cylindrical solid hydrogen pellets (3.4 and 3.8 mm in diameter and length, respectively) at velocities up to 1,200 m/s. The other is a repetitive pellet injector with a screw extruder, which can form a 3.0 mmφ solid hydrogen rod continuously at extrusion rates up to 55 mm/s. This extruder allows consecutive pellet injection up to 11 Hz without time limit. Both of these pellet injectors employ compact cryo-coolers to solidify hydrogen; therefore, they can be operated using only electrical input instead of a complicated liquid helium supply system. In particular, using a combination of the repetitive pellet injector with cryo-coolers provides a steady-state capability with minimum maintenance.

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“…Recent experiments on DIII-O suggest ITER may be able to utilize �3 mm pellets to pace ELMs by injecting them at high frequencies> 15Hz [2]. The ITER pellet injection system is comprised of devices to form and accelerate pellets, and is connected to inner wall guide tubes for fueling, and outer wall guide tubes for ELM mitigation [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Twin-screw extruder and pellet accelerator integration developments for ITER

Meitner

Baylor

Combs

et al. 2011

2011 IEEE/NPSS 24th Symposium on Fusion Engineering

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Abstract-The ITER pellet injection system consisting of a twin screw frozen hydrogen isotope extruder, coupled to a combination solenoid actuated pellet cutter and pneumatic pellet accelerator, is under development at the Oak Ridge National Laboratory.A prototype extruder has been built to produce a continuous solid deuterium extrusion and will be integrated with a secondary section, where pellets are cut, chambered, and launched with a single-stage pneumatic accelerator into the plasma through a guide tube. This integrated pellet injection system is designed to provide 5 mm fueling pellets, injected at a rate up to 10 Hz, or 3 mm edge localized mode (ELM) triggering pellets, injected at higher rates up to 20 Hz. The pellet cutter, chamber mechanism, and the solenoid operated pneumatic valve for the accelerator are optimized to provide pellet velocities between 200-300 mts to ensure high pellet survivability while traversing the inner wall fueling guide tubes, and outer wall ELM pacing guide tubes. This paper outlines the current twin-screw extruder design, pellet accelerator design, and the integration required for both fueling and ELM pacing pellets.

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Pellet fuelling and control of burning plasmas in ITER

Cited by 115 publications

References 28 publications

Observation of Cross-Field Transport of Pellet Plasmoid in LHD

Observation of Cross-Field Transport of Pellet Plasmoid in LHD

Development of Advanced Pellet Injector Systems for Plasma Fueling

Twin-screw extruder and pellet accelerator integration developments for ITER

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