ISM Working Group 1 ITPA meeting 24 th March 2010 Modelling of JET, Tore Supra and Asdex Upgrade current ramp-up experiments F. Imbeaux, F. Köchl, D. Hogeweij, J. Citrin, J. Hobirk, X. Litaudon, V. Basiuk, J. Fereira, J. Lönnroth, V. Parail, G. Pereverzev, Y. Peysson, G. Saibene, M. Schneider, G. Sips, G. Tardini, I. Voitsekhovitch On behalf of : JET-EFDA contributors, Tore Supra workprogram, AUG workprogram, ITER Scenario Modelling group (ITM-TF)

ISM Working Group 2 ITPA meeting 24 th March 2010 Introduction 2 Aim of the working group : model current ramp-up (and ramp- down) in ITER Implications on PF systems, H&CD methods for current profile shaping, flux consumption Main issue is the heat transport model  try to validate a model against present experiments Validation criterion : li and Vloop (0D), Te profile, q-profile, test against several JET experiments (ohmic, NBI, LHCD, ICRH) –A few shots from other experiments : Tore Supra, ASDEX Upgrade Only energy transport and current diffusion are modelled, density and Zeff prescribed from experiment) L mode plasmas

ISM Working Group 3 ITPA meeting 24 th March 2010 What has been done 3 JETTO, CRONOS, ASTRA have been used, not distinguished in the following –We checked that for the same model, results are independent of the transport code Li prediction and Flux consumption are strongly dependent on the Te prediction in the outer half of the plasma  the challenge is to predict Te up to  = 1 in L mode –Models that fail inside  = 0.5 may still be acceptable for predicting li, Vloop Tried a variety of transport models –Scaling-based (prescribed radial shape, renormalised to scalings of global energy content H H-98 = 0.4 or H L-97 = 0.6) –Empirical Bohm/gyro-Bohm (L-mode version, ITB shear function off) –GLF23 (either up to  = 1; or  = 0.8 with large  edge = 8 m 2 /s) –Empirical Coppi-Tang model : could not understand / agree with US colleagues what to use (doubts about the definition of the model)

ISM Working Group 4 ITPA meeting 24 th March 2010 Further details 4 Te, Ti, current transport predicted Vtor not taken into account (usually Vtor, Ti not measured since no NBI) Boundary Te (  = 1) taken from experiment (guessed from ECE) Ne profile taken from experiment (JET : inversion of interferometer : NFT2 PPF) Flat Zeff assumed, taken from experiment (Bremsstrahlung) –Recent reprocessing of KS3 means we have to redo a number of simulations (+20 to + 40 % increase in Zeff). Conclusions on Vloop may be affected, but likely not on the transport model Te profile trends. Prescribed plasma boundary from experiment (EFIT)

ISM Working Group 5 ITPA meeting 24 th March 2010 Present database 5 Current ramp-up : ShotH&CD scheme JET 72823LHCD+moderate NBI JET 72818moderate NBI JET 72516NBI JET 72507ICRH JET 71828ohmic JET 71827ohmic TS 40676ECCD AUG 22110ohmic

ISM Working Group 6 ITPA meeting 24 th March 2010 JET (ohmic) 6 Li reproduced within  li = 0.1 B/gB is the most accurate on li, not necessarily on Te GLF23 needs patch at the edge otherwise strong error in li GLF23 with patch is quite accurate on Te inside  = 0.7

ISM Working Group 7 ITPA meeting 24 th March 2010 JET (2 MW LHCD) 7 Li reproduced within  li = 0.1 (problem during the first 500 ms – too much LH current predicted) B/gB is the most accurate on li, scaling-based better on Te GLF23 needs patch at the edge otherwise strong error in li GLF23 with patch : too flat Te, it is a miracle that it produces so good li

ISM Working Group 8 ITPA meeting 24 th March 2010 JET (2 MW LHCD) 8 NBI blips during ramp-up allowed some MSE and Ti measurements Scaling-based on one hand, B/gB and GLF23 on the other, seem to provide a sort of enveloppe to the experimental data ! Large fluctuations of Ti measurements on this shot

ISM Working Group 9 ITPA meeting 24 th March 2010 JET (ohmic) 9 Li reproduced within  li = 0.1 B/gB and GLF23 accurate in Te and li, scaling-based better tend to overestimate Te in the core Coppi-Tang much too peaked and overestimated on Te.

ISM Working Group 10 ITPA meeting 24 th March 2010 JET (ohmic) 10 Later time All models slightly overestimate Te inside mid-radius, little impact on li NB : average sawteeth effect taken into account in the simulation

ISM Working Group 11 ITPA meeting 24 th March 2010 Tore Supra (ECCD) 11 Li reproduced within  li = 0.1 Co-ECCD at  = 0.3 during the Ip ramp GLF23 gives an excellent prediction of li, though works badly on the electron temperature NB : average sawteeth effect taken into account in the simulation TORE SUPRA

ISM Working Group 12 ITPA meeting 24 th March 2010 Tore Supra (ECCD) 12 Li reproduced within  li = 0.1 Co-ECCD at  = 0.3 during the Ip ramp GLF23 gives an excellent prediction of li, though works badly on the electron temperature NB : average sawteeth effect taken into account in the simulation TORE SUPRA

ISM Working Group 13 ITPA meeting 24 th March 2010 ITER projections, Ip flattop = 15 MA (ohmic) 13 Ip = 15 MA ramped-up in 100 s Prescribed plasma boundary « Ordering » of models in Te prediction is the same as on the JET experiments (scaling-based slightly more optimistic), deviations somewhat larger All « relevant » models give the same li within  li = 0.1 Small differences in target q-profile (  q <= 0.1 outside of q = 1)

ISM Working Group 14 ITPA meeting 24 th March 2010 ITER projections (20 MW ECRH mid-radius) 14 Larger differences in Te due to strong and localised heating All « relevant » models give the same li within  li = 0.1 Some differences in target q0, from flat to slightly reversed, target q above 1 everywhere

ISM Working Group 15 ITPA meeting 24 th March 2010 Conclusions : present experiments 15 A selection of 4 models has been made, matching present JET experiments in terms of li dynamics (within  li = 0.15) for various heating schemes –Same degree of agreement found for a few other discharges from Tore Supra and Asdex Upgrade These models are empirical  –What happens outside  = 0.8 has a strong weight on li –GLF23 needed patch recipe outside  = 0.8 Need to understand : –The « edge barrier » produced by GLF23 when applied up to  = 1 –Why H97 = 0.6 seems the best scaling for ohmic and L-mode during the ramp-up phase

ISM Working Group 16 ITPA meeting 24 th March 2010 Conclusions : ITER projections 16 Same models applied to ITER current ramp-up (ohmic, ECRH) Behavior of models and discrepancies between them similar as when applied to JET cases Range of li prediction remains within  li = 0.1 between models Do not believe this is the absolute prediction of li !  Sensitivity analysis to be carried out on the following parameters : –Zeff, density profile peaking, initial equilibrium conditions, boundary Te conditions –Dependence on plasma boundary shape should also be considered, likely not in self-consistent simulations for the coming conferences EPS paper (D. Hogeweij), IAEA/ITPA paper (F. Imbeaux)

ISM Working Group 17 ITPA meeting 24 th March 2010 Details on scaling-based model 17 Scaling-based : ohmic and L-mode rampup energy content well represented by either –H mode scaling with H 98 = 0.4 –L mode scaling with H 97 = 0.6  i =  e, renormalised so that Fixed  (  ) shape : power balance chi’s during ramp-up tend to be rather flat, then strong increase towards the plasma edge :  ( ,t) = A(t)(1+6   20 )