Recent results on the fuelling and control of plasmas by pellet injection, application to ITER

Pégouriè, B.; Köchl, F.; Nehme, H.; Polevoi, A.

doi:10.1088/0741-3335/51/12/124023

Cited by 22 publications

(25 citation statements)

References 44 publications

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“…However, efficient fuelling is still possible in H-mode using supplementary methods, such as resonant or nonresonant magnetic perturbations in addition to pellet fuelling or using auxiliary heating methods with gas puff during high-frequency pellet injection. [14,15,16,17].…”

Section: Introductionmentioning

confidence: 99%

Pellet cloud characterisation, scaling and estimation of the material- and temperature distribution inside the cloud

et al. 2016

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Using spatially calibrated images of fast visible cameras, a database was established containing pellet cloud images and the related pellet-and plasma parameters. Using this database, two scalings were derived for the cloud size along the magnetic field lines as a function of pellet speed and ablation rate (first case) and pellet speed, pellet volume, plasma temperature and plasma density (second case). Using the images-based on the number of radiation maxima-the four main cloud shapes were also categorized. The isotope effect (the effect of hydrogen pellets in hydrogen or helium plasma) was also investigated with particular attention devoted to the cloud characteristics. Finally, a synthetic diagnostic-which simulates the measurement system and produces a synthetic pellet cloud image based on the output of the pellet cloud simulation-was developed to reveal the underlying densityand temperature distributions of the observed pellet cloud images. Using this synthetic diagnostic, one of the main identified cloud shapes was reconstructed. Our goal is to derive a scaling law for the toroidal extension of the pellet cloud at different pellet-and plasma conditions, to give a more reliable input for the pellet ELM triggering simulations and using these two results-a better understanding of the pellet-caused pressure perturbation.

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Section: Introductionmentioning

confidence: 99%

Pellet cloud characterisation, scaling and estimation of the material- and temperature distribution inside the cloud

et al. 2016

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“…Despite the numerous approximations, this scaling was confirmed for Maxwellian plasmas by more sophisticated models taking into account the other shielding mechanisms and was validated over a large number of experiments in several machines ( [2,3] and references therein, [8,9]).…”

Section: Physics Of Ablationmentioning

confidence: 72%

“…In a fusion reactor, the role of core fueling is (1) to replace the DT consumed in fusion reactions, (2) to compensate the gas exhausted with the Helium ashes and (3), to maintain the central density by compensating the particle outflux across the separatrix (which depends on the transport regime and on the density gradient at the edge).…”

Section: Introductionmentioning

confidence: 99%

“…Despite a deep penetration, Neutral Beam Injection (NBI) cannot be used for fueling, on one hand because it couples particle and power injections, on the other hand because the corresponding fluxes (∼ 6 10 21 (at./s).keV/MW, i.e ∼ 1 Pa m 3 /s for 73 MW injected with 1 MeV neutrals in ITER) are well below the required values. A second option is the injection of cryogenic pellets, a widely documented and mature technique, from both the points of view of the physics [2,3] and of the technical developments [4]. In the future, injection of compact toroids is also envisaged [5], but this technique is not yet developed enough for it to be used in the machines for which beginning of operation is planned during the next decade.…”

Section: Introductionmentioning

confidence: 99%

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Pellet Core Fueling in Tokamaks, Stellarators and Reversed Field Pinches

GEULIN¹,

Pégouriè²

2022

Plasma and Fusion Research

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In a reactor grade device, the role of core fueling is to replace the D and T consumed in the fusion reactions (almost negligible) and to compensate the plasma losses through the separatrix -including the material expelled out by the ELMs. For this purpose, deep material deposition is an advantage and pellet injection the best candidate for fueling the future machines. Fueling by pellet injection consists in two phases: First, the pellet ablation itself, then the ablated material homogenization and drift in the discharge. The former is a self-regulated process, which depends only of the local plasma characteristics. The second is a global phenomenon, which depends on the whole magnetic configuration. In this paper, we discuss first the basics of the ablation physics, emphasizing the role of the fast particles -ions and electrons -resulting from NBI or wave heating; then we describe the homogenization process and associated ∇B-induced drift. The drift acceleration and damping processes are described as well as the influence of the magnetic configuration (tokamak, stellarator and reversed field pinch) on the predominance of a given damping process and its consequence on the resulting deposition profile. We finally review the last results relative to pellet fueling in these different kind of devices and present the ongoing projects for future large-scale machines.

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“…This effect is illustrated in figure 10, where electron temperature and density are shown in the cases of presence and artificially imposed absence of the drift. Particle penetration and core fuelling is therefore strongly dependent on drift, as highlighted also for ITER [18], [31], [32].…”

Section: Variation In the Predicted Exb Plasmoid Driftmentioning

confidence: 90%

Fuelling and density control for DEMO

et al. 2015

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Plasma fuelling and density control are an open issue regarding EU DEMO studies and solutions may be different from present day experiments. The present paper addresses through JINTRAC core transport code simulations the feasibility of different fuelling methods as gas puff and pellet injection and the influence of neoclassical and anomalous inward pinch in the edge transport barrier in order to achieve and control the target DEMO density. Given the expected high fusion power production, He accumulation in the plasma core is a critical issue, and an estimation of the influence of impurities (He, Ar and W) on core fuelling and plasma dilution is given together with a discussion on D-T core balance. The DEMO reference scenario investigated in this work is characterized by a peaked density profile, which requires a careful core fuelling. Due to the large pedestal temperature gradient, gas puff may not be a feasible option for core density control, unless assuming a large anomalous inwards pinch in the edge transport barrier of more than ~2 m/s. Pellet injection from high field side of the torus, on the contrary, may represent a viable solution for core fuelling and D-T ratio control. The effect of pellet mass, speed and injection geometry is also discussed in the present paper. Regardless, core fuelling efficiency with pellet injection is almost entirely determined by the presence of ExB drift.

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Recent results on the fuelling and control of plasmas by pellet injection, application to ITER

Cited by 22 publications

References 44 publications

Pellet cloud characterisation, scaling and estimation of the material- and temperature distribution inside the cloud

Pellet cloud characterisation, scaling and estimation of the material- and temperature distribution inside the cloud

Pellet Core Fueling in Tokamaks, Stellarators and Reversed Field Pinches

Fuelling and density control for DEMO

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