Experimental comparison of recycling and pumping changes during resonant magnetic perturbation experiments at low and high collisionality in DIII-D

Unterberg, E.A.; Brooks, N.H.; Evans, T.E.; Fenstermacher, M.E.; Hillis, D.L.; Maingi, R.; Mordijck, S.; Moyer, R. A.; Osborne, T.H.; Pétrie, T.W.; Watkins, J. G.

doi:10.1016/j.jnucmat.2009.01.052

Cited by 10 publications

(13 citation statements)

References 16 publications

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“…In poloidally diverted H-mode plasmas, application of RMP allows for mitigation [2] and complete suppression [3] of harmful edge localized modes. Here, particle pump out has been observed [4] and 2D modeling with SOLPS5 [5] as well as 1D analytical modeling [6] suggest an enhanced radial particle transport due to magnetic field line diffusion explaining the decrease in the particle confinement observed. The application of RMP in future fusion devices such as ITER and W7-X requires an understanding of the perturbed magnetic field structure and the correlated modification of transport.…”

Section: Introductionmentioning

confidence: 54%

Particle confinement control with resonant magnetic perturbations at TEXTOR

Schmitz

Coenen

Frerichs

et al. 2009

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 54%

Particle confinement control with resonant magnetic perturbations at TEXTOR

Schmitz

Coenen

Frerichs

et al. 2009

Journal of Nuclear Materials

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“…In general, the mitigated ELM behavior also changed with the new divertor geometry along with the recycling behavior as discussed in Ref. [8]. In particular, it was found that full ELM suppression in ISS plasmas requires about 25% more RMP coil current in most parameter regimes studied.…”

Section: Rmp Elm Mitigation and Suppression In Low Collisionality DIImentioning

confidence: 72%

Suppression and Mitigation of Edge Localized Modes in the DIII-D Tokamak with 3D Magnetic Perturbations

Evans

2012

Plasma and Fusion Research

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Uncontrolled Type-I Edge Localize Modes (ELMs) are expected to cause melting of the tungsten divertors in ITER. Methods for controlling ELMs in ITER include pellet pacing and Resonant Magnetic Perturbation (RMP) fields produced by in-vessel, non-axisymmetric, coils. Type-I ELMs have been reproducibly suppressed and mitigated in DIII-D H-mode plasmas with a variety of shapes and pedestal collisionalities using RMP fields of order 10 −3 B T. In these experiments the response of Type-I ELMs to applied RMP fields, with a principal toroidal mode number n = 3, varies dramatically. In some cases there is an evolution in the ELM dynamics involving combinations of small high frequency D α spikes mixed with mitigated Type-I ELMs prior to reaching an ELM suppressed state. In other cases, there is continuous change in the frequency and amplitude of the Type-I ELMs. A reduced set of plasma parameters, that significantly affect the dynamics of the ELMs immediately following the application of the RMP field, have been identified. The dynamics of mitigated ELMs are generally consistent with those seen during Type-I through Type-V ELMs although several new types of ELM dynamics have also been observed in plasmas with relatively low toroidal fields as well as during q 95 ramps.

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“…The results of this calculation for both configurations are shown in figure 1. As can be seen in figures 1(a) and (b) there is a substantial drop in the total number of particles in the core, N p , when the RMP is applied at 2 s. This drop can be up to ∼30% in some discharges [7]. In both discharges the particle input rate is the same, i.e.…”

Section: Comparison Of the Pumping Characteristics And Magnetic Topologymentioning

confidence: 81%

“…The analysis of the pumping characteristics is carried out using a single reservoir particle balance [7,13]. The balance is given by S wall = S IN − S OUT − dN p /dt where S IN is the total particle input rate (i.e.…”

Section: Comparison Of the Pumping Characteristics And Magnetic Topologymentioning

confidence: 99%

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The effects of an open and closed divertor on particle exhaust during edge-localized mode suppression by resonant magnetic perturbations in DIII-D

et al. 2010

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This paper compares the effects of divertor geometry on particle exhaust characteristics during the suppression of ELM using resonant magnetic perturbations (RMPs) on DIII-D. The subject is timely, particularly for ITER, because the combination of techniques to control or mitigate ELMs and control particle exhaust can provide confidence in the ability of an external pumping system to fully remove the particle exhaust. The differences between an open and closed divertor magnetic topology show a strong coupling of the perturbed strikepoint to the pumping manifold in closed divertor configurations, which can increase the particle exhaust by a factor of four. There is also an observed dependence on q 95 in this configuration, which is a common feature of RMP ELM suppression. Neutral density in both the active and non-active divertors is seen to increase during the RMP in the ISS configuration, and edge plasma conditions (i.e. n e,sep and midplane profile of D α) are seen to increase in the closed divertor configuration. Finally, the pumping exhaust is also shown to have a strong dependence on local measurements of the recycling flux. These observations, when taken as a whole, point to a substantial change in the plasma edge conditions, i.e. near the LCFS, throughout the poloidal cross-section of the vacuum vessel. This is coincident with the application of the RMP affecting the pumping capability of the system.

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Experimental comparison of recycling and pumping changes during resonant magnetic perturbation experiments at low and high collisionality in DIII-D

Cited by 10 publications

References 16 publications

Particle confinement control with resonant magnetic perturbations at TEXTOR

Particle confinement control with resonant magnetic perturbations at TEXTOR

Suppression and Mitigation of Edge Localized Modes in the DIII-D Tokamak with 3D Magnetic Perturbations

The effects of an open and closed divertor on particle exhaust during edge-localized mode suppression by resonant magnetic perturbations in DIII-D

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