Non-linear MHD modelling of 3-D plasma edge with Resonant Magnetic Perturbations in DIII-D and ITER

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Non-linear MHD modelling of 3-D plasma edge with Resonant Magnetic Perturbations in DIII-D and ITER

M Becoulet, G Huijsmans, D Orlov, R Moyer, T Evans, S Futatani

To cite this version:

M Becoulet, G Huijsmans, D Orlov, R Moyer, T Evans, et al.. Non-linear MHD modelling of 3-D plasma edge with Resonant Magnetic Perturbations in DIII-D and ITER. 46th conference on plasma physics (EPS), Jul 2019, Milan, Italy. �hal-02796508�

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1_{CEA, IRFM, 13108 Saint-Paul-Lez-Durance, France} 2_{Eindhoven University of Technology, Eindhoven, The} Netherlands

3_{Center for Energy Research, University of California San} Diego, La Jolla, CA 92093, USA

4_{General Atomics, PO Box 85608, San Diego, CA} 92186-5608, USA

Non-linear MHD modelling of 3-D plasma edge with Resonant

Magnetic Perturbations in DIII-D and ITER.

M. Becoulet1_{, G.T.A. Huijsmans}1,2_{, D.M. Orlov}3_{, R.A. Moyer}3_{, T.E. Evans}4_,

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Marina Bécoulet, P1.1047, 46th EPS, July 8 -12, 2019, Milan, Italy 2

Abstract:

Edge Localized Modes (ELMs) potentially represent an issue for the ITER divertor lifetime due to large transient heat and particle losses released in ELM relaxations. The application of small Resonant Magnetic Perturbations (RMPs) demonstrated the possibility of total ELMs suppression or mitigation of their size, motivating the use of such method in ITER. The important drawback of RMPs and intrinsic error fields in general is the complex magnetic topology at the edge and formation of a 3D Scrape of Layer (SOL) leading to the splitting of the separatrix, seen in experiment as helical “lobes” near the X-point. The non-axisymmetric divertor fluxes with RMPs can represent an issue in ITER leading to local high heat fluxes (“hot spots”) in the unprotected areas, additional material erosion and fatigue stress on the divertor components.

In this work the characterisation of 3D plasma edge with RMPs was done using the non-linear MHD code JOREK. Firstly, the validation of RMP model implemented in JOREK was done comparing simulation results with measurements of divertor particle flux splitting during ELM suppression experiment on DIII-D. Secondly, the results of JOREK modelling of ITER divertor magnetic footprints and divertor fluxes with RMPs generated by ELM Coils are presented for standard H-mode scenario at 15MA/5.3T.

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• RMPs lead to 3D SOL : lobes formation , not axisymmetric heat and particle fluxes. Impact of 3D fields on divertor erosion in ITER even if ELMs are suppressed?

• Loss of fast particles (alphas, NBI) due to ergodic fields?

• Imaging can help in understanding of the physics of RMPs and validate plasma response models implemented in MHD codes.

Motivation: 3D structure of the divertor heat and particle fluxes with RMPs is a critical issue for ITER. Predictive modelling for ITER? Validation of models on existing RMP experiments first!

h eat flu x p ar ticle flu x

Splitting in particle flux in RMP suppression experiments DIIID#166439 (I-coils+C-coils+intrinsic error fields) measured by FASTCAM (D₂ emission imaging in divertor).

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Marina Bécoulet, P1.1047, 46th EPS, July 8 -12, 2019, Milan, Italy

JOREK. Non-linear resistive MHD with rotation, two fluid

diamagnetic effects, X-point, SOL. Realistic geometry. Bohm conditions on (V// =Cs ) divertor. Vacuum RMPs are given on computational boundary.

[Huysmans NF2007, OrainPoP2013, Becoulet PRL2014]

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I-coil C-coil Intrinsic error fields

All 3D fields

Parameters of DIII-D #166439. I coils, C-coils, intrinsic 3D fields are calculated in vacuum. Main toroidal harmonics N=1

(C-coils) and N=3 (I-(C-coils) are taken into account.

spectrum

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Initial experimental &JOREK profiles

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RMPs are switched on progressively in time on the computational boundary (=vacuum).

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Equilibrium with flows

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Vacuum Plasma

Plasma Plasma

Perturbations at toroidal angle 0°(~stationary RMPs, at t2 )

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Heat and particle sources were adapted to keep density and temperature profiles close to the initial

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Vacuum

Plasma

Comparison vacuum vs plasma response

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Comparison magnetic topology in vacuum and with plasma response

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Vacuum Plasma

Screening of RMPs by plasma: lobes and stochastic layer are smaller. Crossing with HFS target is different for

vacuum and with plasma response (~closer to experiment)

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Screening of resonant harmonics by plasma

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Vacuum

With plasma response

Magnetic footprints in inner divertor

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A rather good correspondence with the particle flux splitting measurements by FASTCAM in DIII-D#166934 and modelled magnetic footprints with non-linear MHD plasma response was obtained.

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Note also that equilibrium with flows and with RMPs is shifted towards LFS. Divertor magnetic footprints are very sensitive to (even small ) magnetic surfaces

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Non-linear evolution of radial electric field and

perpendicular electron velocity while RMP penetrates into plasma. Er “well” and Vperp_e decrease.

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30 , 40 , 200 , 150 ;            0, cos( ( ( 1)) ) /180) up up up up j A n  i   ITER ITER ELM Coils. 15MA/5.3T H-mode standard scenario.

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(dW_th/dt0)

.

RMPs are switched on progressively in time on the computational boundary (=vacuum).

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ITER Density with RMP n=3,45kAt and perpendicular divertor

heat flux in ITER. Total power in divertor in stationary regime: 100MW. .

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ITER Poloidal magnetic flux, current and density perturbations

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(dW_th/dt0)

Magnetic topology (left) and density (right) near X-point with RMPs n=3,45kAt in ITER

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Magnetic footprints in inner and outer divertors with RMPs n=3,45kAt in ITER

at toroidal angle 180°

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Heat flux splitting in inner and outer divertors with RMPs n=3,45kAt in ITER

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Particle flux splitting in inner and outer divertors with RMPs n=3,45kAt in ITER.

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Conclusions.

1. Inner strike point magnetic footprints splitting due to RMPs obtained in modelling using the non-linear resistive MHD code JOREK showed rather good correspondence to particle flux splitting measured by FASTCAM on DIII-D.

2. Initial results of ITER divertor magnetic footprints and splitting of divertor heat and particle fluxes with RMPs n=3, 45kAt were calculated for

standard H-mode scenario 15MA/5.3T.

3. For more quantitate estimations more divertor physics (recycling of neutrals, ionization, recombination, radiation etc) will be included in the future work.

Acknowledgements: This work has been supported by EUROFUSION CfP-WP19-ENR-01/MPG-03, IO/CT/18/430000 and US DOE under