Heat and Particle Physics analysis in advanced tokamak plasmas from JET and JT-60U

J. Garcia1, N. Hayashi2, C. Challis3, M. Honda2, G. Giruzzi1, S. Ide2, Y. Sakamoto2, T. Suzuki2, H. Urano2, the JT-60 Team and JET contributors*EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK1 CEA, IRFM, 13108 Saint-Paul-lez-Durance, France2Japan Atomic Energy Agency, Mukouyama, Naka City, Ibaraki, 311-0193 Japan3CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK

Outline

• Physics understanding and model validation: A clear necessity for extrapolation

• Models and first principles tools used 

• Heat, particle and pedestal physics analysis with JET and JT‐60U discharges

• An example of extrapolation: JET‐DT based on hybrid

• Heat and particle transport in ITB regimes

• Conclusions

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OutlineMain goal: Extrapolation of JET and JT‐60U plasmas towards JT‐60SA 

predictions

Extrapolation performed in several parallel steps

• Representative discharges of  baseline H‐mode, hybrid and steady‐state have been selected from JET and JT‐60U

• Models for heat and particle transport, pedestal pressure, heating sources, current diffusion

• Turbulence analyzed with gyrokinetic codes

Extrapolation

Experimental results

Model validation

Physics understanding: first principle 

physics

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Outline• Extensive physics analysis of the main similarities and differences among thedischarges

• The integrated modelling codes CRONOS and TOPICS used. Benchmark of the codes done

• Predictive core turbulence simulations with three transport models: Bohm‐GyroBohm,CDBM and GLF23.

• The analyses has been extended to TGLF

• Particle transport analyzed with GLF23 and TGLF.

• Pedestal pressure analyzed with scaling [Cordey NF2003]

• Inductive H‐mode and hybrid discharges already analysed [Garcia NF14]

• Inductive H‐mode and hybrid extrapolations to JT‐60SA already performed with CDBM andGLF23 [Garcia NF14]

• Discharges with Internal Transport Barrier (ITB) being analysed [Hayashi APS14]

09.22.013.281.106.008.042.008.158.1000643.0 qaped FmBnPRIW

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JT-60U and JET inductive H-mode

• First step: Inductive H‐mode heat transport modelling• Good agreement between CRONOS and TOPICS• Good agreement between the models for JET and JT‐60U discharges• Particular good agreement for GLF23• General trend for all the inductive H‐mode discharges analyzed. Is there anyphysical reason for this agreement?

JET 73344JT‐60U 33655

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JT-60U and JET inductive H-mode

• Linear growth and frequencies rates calculated with the GENE code [Jenko et al.,PoP 2000]

• ITG modes with 0<ky<1 are dominant

• Quasi‐linear approximation for turbulence mostly validated for ITG

• Confidence on the extrapolation of heat transport to ITG regimes (without strongsuppression of transport)

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JT-60U and JET hybrid

• Heat transport analysis performed with hybrid discharges• General good agreement between the codes• Ion temperature overestimated by GLF23 and BGB (including turbulencesuppression by ExB flow shear)

• Better agreement with CDBM• General trend for the Hybrids analyzed

JT‐60U 48158 JET 75225

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JT-60U and JET hybrid

• A zoo of different modes appear for “apparently” similar discharges

• JET 75225: ITG are dominant (but KBM can appear if fast ion component added)[Garcia NF15] [Citrin PPCF14]

• JT‐60U 48158: both KBM (even without fast ions) and TEM are present (highdensity peaking)

• Quasi‐linear approximation in these regimes has to be carefully checked

• Different turbulent regimes can lead to different behavior of the transport modelsapplied

JT‐60U 48158

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JT-60U and JET hybrid

• Hybrid discharges 75225 and 48158 simulated with GLF23 (assuming αExB=1.35or αExB=0 for GLF23)

• The impact of rotation is very strong and overestimates Ti• Without ExB flat temperatures obtained for JT‐60U 48158• This region linked to TEM. Reduction of Lne leads to JET behavior• β effects and fast ions interplay, important for turbulence suppression [GarciaNF15] , neglected in GLF23

JET 75225 JT‐60U 48158

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Reduced Lne

Particle transport JT-60U and JET

• Heat and particle transport analyzed• Ne,ped adjusted to experimental data• GLF23 used for inductive H‐mode (both heat and particle transport)• GLF23 and CDBM used (heat transport) and GLF23 for particle transport forhybrid

• Density reasonably well simulated. Strong density peaking obtained for hybrid• In the case of hybrid the two models applied give a margin of confidence

JT‐60U 33654 JET 75225

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Particle transport JT-60U and JET

• Sensitivity of the density peaking analyzed: Core fuelling (NBI) and ExBmechanisms

• GLF23 transport model applied. Sensitivity to ExB analyzed by switching fromαExB=1.35 to αExB=0

• Both effects contribute in a similar way to the density peaking• Strong impact of ExB on particle confinement found in DIII‐D [Mordijck IAEA14]• Up to 25% less density peaking when both effects are removed

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JET 75225 JT‐60U 48158

Pedestal prediction

• Full simulation: Current diffusion, heat and particle transport, sources +pedestal pressure height

• Ne,ped calculated by assuming neoclassical particle transport• T,ped following Cordey scaling• Reasonable agreement for inductive H‐mode and hybrid pedestal dischargesanalyzed

• Modelling can be performed including core‐edge interplays (essential for explainlow power degradation [Challis NF15] [Garcia NF 15])

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JET 73344

Extrapolation methodology: JET-DT

PNBI

H98(y,2)

βN

Time

• The  previous methodology applied to extrapolation to JET‐DT• High‐β scenario expected to play a role in JET‐DT• Plasmas analysed: weak power degradation, especially at high power, obtained 

both at high and low delta

C.D. Challis et al 2015 Nucl. Fusion 55 053031

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• High power discharge from power scan. Pnbi=13MW • Neutrals adjusted to match Ne,ped• Full self‐consistent simulation (except pedestal width) with TGLF• Electromagnetic effects, fast ions and ExB flow shear applied (shown to 

play important role at high‐β for this discharge) [Garcia NF15]• Temperatures well simulated and correct density peaking obtained

Extrapolation methodology: JET-DT

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Half power simulation

• Shot 84798 at Pnbi≈6MW: Higher edge density (less peaking) than 84792• Half power applied to the 84792 modeling compare with 84798• Density profile well predicted if Ne,ped is readjusted• Core temperatures and pedestal pressure reasonably well predicted• The modelling is able to reproduce the low power degradationSelf‐

consistent modeling of the pedestal needed• Confidence on JET‐DT extrapolation

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Equivalent Fusion power

• Increased NBI power, Ip and Bt. Fusion yield calculated with experimental and simulated profiles and compared with discharge 86614 at medium power.

• Full power available (≈40MW) applied• Uncertainties in the pedestal density analyzed by performing a sensitivity scan• Low densities important for higher fusion yield Modeling helps to plan future 

JET campaigns

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JT-60U & JET ITB plasmas with full CDDischarge q95 κ/δ Bt (T) βN

fGW=ne /nGW

Ip(MA) Pin (MW)

JT-60U 43046 8.4 1.59/0.41 3.4 1.7 0.58 0.8 4.5

JT-60U 48246 5.3 1.47/0.37 2.0 2.7 0.88 0.8 8.1

JET 53521 5.7 1.65/0.20 3.5 1.7 0.40 2.0 15(NB)4(IC),3(LH)

ne & q profiles

JT-60U 43046 48246 JET 53521

qmin ~ 3.2

qmin ~ 2.3 qmin ~ 2.2

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ITB heat transport: JT-60U 43046

• ITB discharges analyzed in with the same methodology• General agreement between TOPICS & CRONOS• All three models produce lower temperatures than experimentespecially for Ti.

• Region of flat temperature with GLF23Consequence of very highdensity peaking (TEM)

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ITB heat transport: JT-60U 48246

• General agreement between TOPICS & CRONOS• Good prediction by CDBM. Under or overestimated temperatures withBGB and GFL23

• TEM lead to flat temperature profiles• CDBM gives a conservative prediction of ITB plasmas at JT‐60U

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ITB heat transport: JET 53521

• General agreement between TOPICS & CRONOS• Good prediction by CDBM. Under or overestimated temperatures withBGB and GFL23

• Similar trend in JET as in JT‐60U• CDBM can be used as a conservative prediction of ITB (important for JT‐60SA)

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ITB particle transport: JET 53521

• Particle transport in ITB analyzed for JET

• ITB obtained for particle channel, but very weak and wrong ITB foot

• Enough physical understanding of particle transport?

• Can models simulate TEM regimes?Gyrokinetic revision of ITB needed

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Conclusions• JET and JT‐60U heat and particle transport analyzed: essential for extrapolation to future devices like JT‐60SA [L. Garzotti  this conference][Hayashi APS14] 

• Interplay between experiment, modeling and theory is mandatory

• Self‐consistent core‐edge simulations are necessary for extrapolation

• ITG driven turbulence well captured by models  Confidence on baseline scenario extrapolation

• Advanced tokamak regimes, with a variety of turbulence modes and turbulence suppression, are a challenge : Partially understood

• CDBM model captures the ITB formation and it is conservative for advanced tokamak scenarios extrapolation

• Heat transport widely analyzed in the past  New focus on particle transport (density peaking, ITB, role of ExB)

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