Physics of penetration of resonant magnetic perturbations used for Type I edge localized modes suppression in tokamaks

Bécoulet, M.; Huysmans, G.; Garbet, X.; Nardon, E.; Howell, D. F.; Garofalo, A. M.; Schaffer, M. J.; Evans, T.E.; Shaing, K. C.; Cole, Andrew J.; Park, J. K.; Cahyna, P.

doi:10.1088/0029-5515/49/8/085011

Cited by 89 publications

(120 citation statements)

References 22 publications

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“…Note that to further study the evolution of the plasma rotation in presence of RMPs, the physics of the toroidal momentum damping by the neoclassical toroidal viscosity (NTV) should be taken into account [45,46]. To do it properly, it would be necessary to calculate the NTV with a kinetic approach by using as input the magnetic field perturbation which takes into account the plasma response; the coupling between the kinetic calculation of the NTV with the MHD calculation of the penetration of the RMPs in JOREK would give a self-consistent approach.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

et al. 2013

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The interaction of static Resonant Magnetic Perturbations (RMPs) with the plasma flows is modeled in toroidal geometry, using the non-linear resistive MHD code JOREK, which includes the X-point and the Scrape-Off-Layer. Two-fluid diamagnetic effects, the neoclassical poloidal friction and a source of toroidal rotation are introduced in the model to describe realistic plasma flows. RMP penetration is studied taking self-consistently into account the effects of these flows and the radial electric field evolution. JET-like, MAST and ITER parameters are used in modeling. For JET-like parameters, three regimes of plasma response are found depending on the plasma resistivity and the diamagnetic rotation: at high resistivity and slow rotation, the islands generated by the RMPs at the edge resonant surfaces rotate in the ion diamagnetic direction and their size oscillates. At faster rotation, the generated islands are static and are more screened by the plasma. An intermediate regime with static islands which slightly oscillate is found at lower resistivity. In ITER simulations, the RMPs generate static islands, which forms an ergodic layer at the very edge (ψ ≥ 0.96) characterized by lobe structures near the X-point and results in a small strike point splitting on the divertor targets. In MAST DND geometry, lobes are also found near the X-point and the 3D-deformation of the density and temperature profiles is observed.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

et al. 2013

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“…screening), amplification of certain harmonics is also possible depending on how close to the tearing instability threshold local plasma parameters are [69]. Calculations, which include diamagnetic rotation [70] and neoclassical radial electric field [72] predict that screening of the external field increases for lower resistivity and stronger plasma rotation. Diamagnetic effects and equilibrium electric field are of particular importance for screening in the pedestal region in which large gradients occur.…”

Section: Status Of Physics Understanding and Extrapolation To Itermentioning

confidence: 99%

“…MAST) and why predicted deposition "footprints" in the divertor are seen on JET and MAST in L-mode, but not in H-mode [73]. Presumably, screening due to the poloidal rotation (ExB and diamagnetic) is larger in the H-mode pedestal region than in Lmode [70]. In DIII-D H-modes, divertor strike zone splitting into helical "homoclinic tangles" is seen [74], but as mentioned above, it is less strong on heat flux compared to particle flux onto the divertor plates.…”

Section: Status Of Physics Understanding and Extrapolation To Itermentioning

confidence: 99%

ELM control strategies and tools: status and potential for ITER

et al. 2013

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Operating ITER in the reference inductive scenario at the design values of I P = 15 MA and Q DT = 10 requires the achievement of good H-mode confinement that relies on the presence of an edge transport barrier whose pedestal pressure height is key to plasma performance. Strong gradients occur at the edge in such conditions that can drive MHD instabilities resulting in Edge Localized Modes (ELMs), which produce a rapid energy loss from the pedestal region to the plasma facing components. Without appropriate control, the heat loads on plasma facing components during ELMs in ITER are expected to become significant for operation in H-mode at I P = 6 -9 MA; operation at higher plasma currents would result in a very reduced life time of the plasma facing components. Currently, several options are being considered for the achievement of the required level of ELM control in ITER; this includes operation in plasma regimes which naturally have no or very small ELMs, decreasing the ELM energy loss by increasing their frequency by a factor of up to 30 and avoidance of ELMs by actively controlling the edge with magnetic perturbations. Small/no ELM regimes obtained by influencing the edge stability (by plasma shaping, rotational shear control, etc.) have shown in present experiments a significant reduction of the ELM heat fluxes compared to type-I ELMs. However, so far they have only been observed under a limited range of pedestal conditions depending on each specific device and their extrapolation to ITER remains uncertain. ELM control by increasing their frequency relies on the controlled triggering of the edge instability leading to the ELM. This has been 2 presently demonstrated with the injection of pellets and with plasma vertical movements; pellets having provided the results more promising for application in ITER conditions. ELM avoidance/suppression takes advantage of the fact that relatively small changes in the pedestal plasma and magnetic field parameters seem to have a large stabilizing effect on large ELMs. Application of edge magnetic field perturbation with non-axisymmetric fields is found to affect transport at the plasma edge and thus prevent the uncontrolled rise of the plasma pressure gradients and the occurrence of type-I ELMs. This paper compiles a brief overview of various ELM control approaches, summarizes their present achievements and briefly discusses the open issues regarding their application in ITER. IntroductionThe main goal of current research in the field of magnetically confined plasmas aiming for power generation by nuclear fusion is to optimize high confinement plasma regimes (Hmode) in order to achieve the maximum plasma energy for a given input heating power P in . Thus, in future fusion devices such as the ITER tokamak, which is expected to produce considerable amounts of fusion power P fus , the gain or amplification factor Q = P fus /P in requires to be maximized as well. High confinement H-mode plasmas are characterized by the existence of an Edge Transport Barrier (ETB) in a ...

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“…Bécoulet et al have examined the role of NTV forces in the context of ELM-suppression experiments [53]. Since the NTV and resonant forces are additive, however, in this paper we will restrict consideration to the resonant forces.…”

Section: Onset Of Locked Modesmentioning

confidence: 99%

Role of singular layers in the plasma response to resonant magnetic perturbations

et al. 2012

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Abstract. The response of an H-mode plasma to magnetic perturbations that are resonant in the edge is evaluated using a fluid model. With two exceptions, the plasma rotation suppresses the formation of magnetic islands, holding their widths to less than a tenth of those predicted by the vacuum approximation. The two exceptions are at the foot of the pedestal, where the plasma becomes more resistive, and at the surface where the perpendicular component of the electron velocity reverses. The perturbations exert a force on the plasma that is such as to brake the perpendicular component of the electron rotation. In the pedestal, the corresponding Maxwell stress drives the radial electric field in such a way as to accelerate ion rotation. Despite the suppression of the islands, the perturbations give rise to particle fluxes caused by magnetic flutter, with a negligible contribution from E×B convection. In the pedestal, the fluxes are such as to reduce the density.

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Physics of penetration of resonant magnetic perturbations used for Type I edge localized modes suppression in tokamaks

Cited by 89 publications

References 22 publications

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

ELM control strategies and tools: status and potential for ITER

Role of singular layers in the plasma response to resonant magnetic perturbations

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