Super-X divertors and high power density fusion devices

Valanju, P.; Kotschenreuther, M.; Mahajan, S. M.; Canik, J.

doi:10.1063/1.3110984

Cited by 206 publications

(167 citation statements)

References 14 publications

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“…This prevents filaments from re-establishing an electrical connection to the sheath, as predicted in [50]. Simulations including cross-field variation in the magnetic geometry are certainly a topic which should be pursued, especially with the development of more complicated divertor geometries such as the snowflake [53,54,55,56] or the Super-X [57,58,59] concepts. It is also important to recognise that no variation in the background parameters of the simulation along the field line have been included.…”

Section: Resultsmentioning

confidence: 99%

Characterization of 3D filament dynamics in a MAST SOL flux tube geometry

Walkden

Dudson

Fishpool

2013

Plasma Phys. Control. Fusion

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Abstract. Non-linear simulations of filament propagation in a realistic MAST SOL flux tube geometry using the BOUT++ fluid modelling framework show an isolation of the dynamics of the filament in the divertor region from the midplane region due to three features of the magnetic geometry; the variation of magnetic curvature along the field line, the expansion of the flux tube and strong magnetic shear. Of the three effects, the latter two lead to a midplane ballooning feature of the filament, whilst the former leads to a ballooning around the X-points. In simulations containing all three effects the filament is observed to balloon at the midplane, suggesting that the role of curvature variation is sub-dominant to the flux expansion and magnetic shear. The magnitudes of these effects are all strongest near the X-point which leads to the formation of parallel density gradients. The filaments simulated, which represent filaments in MAST, are identified as resistive ballooning, meaning that their motion is inertially limited, not sheath limited. Parallel density gradients can drive the filament towards a Boltzmann response when the collisionalityof the plasma is low. The results here show that the formation of parallel density gradients is a natural and inevitable consequence of a realistic magnetic geometry and therefore the transition to the Boltzmann response is a consequence of the use of realistic magnetic geometry and does not require initializing specifically varying background profiles as in slab simulations. The filaments studied here are stable to the linear resistive drift wave instability but are subject to the non-linear effects associated with the Boltzmann response, particularly Boltzmann spinning. The Boltzmann response causes the filament to self-organise and spin on an axis. In later stages of its evolution a non-linear turbulent state develops where the vorticity evolves into a turbulent eddy field on the same length scale as the parallel current. The transition from interchange motion to the Boltzmann response occurs with increasing temperature through a decrease in collisionality. This is confirmed by measuring the correlation between density and potential perturbations within the filament, which is low in the anti-symmetric state associated with the interchange mechanism, but high in the Boltzmann regime. In the Boltzmann regime net radial transport is drastically reduced whilst a small net toroidal transport is observed. This suggests that only a subset of filaments, those driven by the interchange mechanism at the separatrix, can propagate into the far SOL. Filaments in the Boltzmann regime will be confined to the near separatrix region and quickly disperse. It is plausible that filaments in both regimes can contribute to the SOL transport observed in experiment; the former by propagating the filament into the far SOL and the latter by dispersion of the density within the filament.

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Section: Resultsmentioning

confidence: 99%

Characterization of 3D filament dynamics in a MAST SOL flux tube geometry

Walkden

Dudson

Fishpool

2013

Plasma Phys. Control. Fusion

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“…Few novel concepts, magnetic configurations and geometry of divertors, targeting this issue, were suggested in recent years (see e.g. Kotschenreuther 2004;Ryutov 2007;Valanju et al 2009;LaBombard et al 2015;Goldston et al 2017). The so-called 'snowflake' divertor configuration (Ryutov 2007) has already been tested in a few tokamaks and has shown a good performance (see e.g.…”

Section: Transient Effects In the Detached Divertor Regimementioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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The basic physics of the processes playing the most important role in divertor plasma detachment is reviewed. The models used in the two-dimensional edge plasma transport codes that are widely used to address different issues of the edge plasma physics and to simulate the experimental data, as well as the numerical schemes and convergence issues, are described. The processes leading to ultimate divertor plasma detachment, the transition to and the stability of the detached regime, as well as the impact of the magnetic configuration and divertor geometry on detachment, are considered. A consistent, integral physical picture of ultimate detachment of a tokamak divertor plasma is developed.

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“…Impurities released from the contact zones with the plasma are mostly retained inside the divertor. The magnetics of divertors is still an area of R&D with new concepts emerging, dubbed Super-X [9] or snow-flake divertor [10].…”

Section: -P14mentioning

confidence: 99%

Physics of magnetic confinement fusion

Wagner

2013

EPJ Web of Conferences

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Summary. -Fusion is the energy source of the universe. The local conditions in the core of the Sun allow the transfer of mass into energy, which is finally released in the form of radiation. Technical fusion melts deuterons and tritons to helium releasing large amounts of energy per fusion process. Because of the conditions for fusion, which will be deduced, the fusion fuel is in the plasma state. Here we report on the confinement of fusion plasmas by magnetic fields. Different confinement concepts -tokamaks and stellarators-will be introduced and described. The first fusion reactor, ITER, and the most modern stellarator, Wendelstein 7-X, are under construction. Their basic features and objectives will be presented. -IntroductionEnergy is the most important commodity man needs on Earth. It provides mankind with food and energy makes it largely independent of the perils of nature. It is not astonishing that energy consumption rose in the last centuries in parallel to the number of inhabitants on Earth. The relation between consumed energy and population is about quadratic because the per-capita energy consumption also increases over the years. It is expected that energy consumption will double till 2050 as a consequence of the population EPJ Web of Conferences

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Super-X divertors and high power density fusion devices

Cited by 206 publications

References 14 publications

Characterization of 3D filament dynamics in a MAST SOL flux tube geometry

Characterization of 3D filament dynamics in a MAST SOL flux tube geometry

Physics of ultimate detachment of a tokamak divertor plasma

Physics of magnetic confinement fusion

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