Experiments to test an intra-island scoop limiter on TEXT

Evans, T.E.; deGrassie, J.S.; Jackson, G.L.; Ohyabu, N.; Wootton, A. J.; Gentle, K. W.; Hodge, W. L.; McCool, S. C.; Phillips, P. E.; Rhodes, T. L.; Richards, B.; Ritz, Ch. P.; Rowan, W. L.; Karger, F.; Haas, G.

doi:10.1016/0022-3115(87)90451-x

Cited by 44 publications

(42 citation statements)

References 9 publications

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“…In addition, as was first seen on TEXT [27], externally imposed fields can lead to both decreases and increases in electron temperature gradients. Accordingly, the puzzle posed by the present results is common to a number of experiments on both limiter and divertor tokamaks.…”

Section: Discussionmentioning

confidence: 98%

ELM suppression in low edge collisionality H-mode discharges usingn= 3 magnetic perturbations

Burrell

Evans

Doyle

et al. 2005

Plasma Phys. Control. Fusion

118

151

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Abstract. Using resonant magnetic perturbations with toroidal mode number n = 3, we have produced H-mode discharges without edge localized modes (ELMs) which run with constant density and radiated power for periods up to about 2550 ms (17 energy confinement times). These ELM suppression results are achieved at pedestal collisionalities close to those desired for next step burning plasma experiments such as ITER and provide a means of eliminating the rapid erosion of divertor components in such machines which could be caused by giant ELMs. The ELM suppression is due to an enhancement in the edge particle transport which reduces the edge pressure gradient and pedestal current density below the threshold for peeling-ballooning modes. These n = 3 magnetic perturbations provide a means of active control of edge plasma transport.2

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Section: Discussionmentioning

confidence: 98%

ELM suppression in low edge collisionality H-mode discharges usingn= 3 magnetic perturbations

Burrell

Evans

Doyle

et al. 2005

Plasma Phys. Control. Fusion

118

151

View full text Add to dashboard Cite

show abstract

“…Theoretical analysis [35][36][37][38] and experimental results in L-mode and Ohmic plasmas [46,[49][50] have consistently identified electron thermal conduction as the dominant transport mechanism. We have…”

Section: Discussionmentioning

confidence: 99%

Calculation of stochastic thermal transport due to resonant magnetic perturbations in DIII-D*

et al. 2008

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Abstract. The effect of resonant magnetic perturbations on heat transport in DIII-D H-mode plasmas has been calculated by combining the TRIP3D field-line tracing code with the E3D two-fluid transport code. Simulations show that the divertor heat flux distribution becomes non-axisymmetric because heat flux is efficiently guided to the 2 divertor along the three-dimensional invariant manifolds of the magnetic field.Calculations demonstrate that heat flux is spread over a wider area of the divertor target, thereby reducing the peak heat flux delivered during steady-state operation. Filtered optical cameras have observed non-axisymmetric particle fluxes at the strike-point and Langmuir probes have observed non-axisymmetric floating potentials. On the other hand, the predicted magnitude of stochastic thermal transport is too large to match the pedestal plasma profiles measured by Thomson scattering and charge exchange recombination spectroscopy. The Braginskii thermal conductivity overestimates the experimental heat transport in the pedestal because the mean free paths of both species are longer than estimates of the parallel thermal correlation lengths, and collisionless transport models are probably required for accurate description. However, even the collisionless estimates for electron thermal transport are too large by one to two orders of magnitude. Thus, it is likely that another mechanism such as rotational screening of resonant perturbations limits the stochastic region and reduces transport inside of the pedestal.

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“…32͒ and DIII-D, 33 and ELM-free operation in the QH-mode. [34][35][36][37][38][39] Pioneering work on the effect of edge stochastic fields in circular limited plasmas was done by the TEXT group, [40][41][42][43] by the Tore-Supra group ͑Refs. 44 and 45, and references therein͒, and by the TEXTOR group.…”

Section: Introductionmentioning

confidence: 99%

Effect of island overlap on edge localized mode suppression by resonant magnetic perturbations in DIII-D

Fenstermacher¹,

Evans²,

Osborne³

et al. 2008

Physics of Plasmas

151

230

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Recent DIII-D [J. L. Luxon et al., Nucl. Fusion 43, 1813 (2003)] experiments show a correlation between the extent of overlap of magnetic islands induced in the edge plasma by perturbation coils and complete suppression of Type-I edge localized modes (ELMs) in plasmas with ITER-like electron pedestal collisionality νe*∼0.1, flux surface shape and low edge safety factor (q95≈3.6). With fixed amplitude n=3 resonant magnetic perturbation (RMP), ELM suppression is obtained only in a finite window in the edge safety factor (q95) consistent with maximizing the resonant component of the applied helical field. ELM suppression is obtained over an increasing range of q95 by either increasing the n=3 RMP strength, or by adding n=1 perturbations to “fill in” gaps between islands across the edge plasma. The suppression of Type-I ELMs correlates with a minimum width of the edge region having magnetic islands with Chirikov parameter >1.0, based on vacuum calculations of RMP mode components excluding the plasma response or rotational shielding. The fraction of vacuum magnetic field lines that are lost from the plasma, with connection length to the divertor targets comparable to an electron-ion collisional mean free path, increases throughout the island overlap region in the ELM suppressed case compared with the ELMing case.

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Experiments to test an intra-island scoop limiter on TEXT

Cited by 44 publications

References 9 publications

ELM suppression in low edge collisionality H-mode discharges usingn= 3 magnetic perturbations

ELM suppression in low edge collisionality H-mode discharges usingn= 3 magnetic perturbations

Calculation of stochastic thermal transport due to resonant magnetic perturbations in DIII-D*

Effect of island overlap on edge localized mode suppression by resonant magnetic perturbations in DIII-D

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