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T&C ITPA group meeting, 4-6 April 2011

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T&C ITPA group meeting, 4-6 April 2011

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  1. Draft of ISM talk on T&C ITPA for discussion/completion: ISM modelling activity on current ramp upPresented by I VOITSEKHOVITCH on behalf of ISM groupTF Leader : G. Falchetto Deputies: R. Coelho, D. CosterISM Leader: X. LitaudonISM Deputy Leader: I. Voitsekhovitch EFDA CSU Contact Person: D. Kalupin T&C ITPA group meeting, 4-6 April 2011

  2. Outline • Introduction • Validation of transport models for current ramp up plasmas • Current diffusion: is it consistent with neoclassical predictions? • Projection to ITER

  3. About ISM: general information • Created in 2007 as ITM cross-project. Status of ITM project since 2010 • Activity proceeds via: 3 working sessions per year + regular remote meetings (~every two weeks). • Resources in 2010/2011: - 47 participants, 6.86 PPY (Basic and priority support) - CCFE, CEA, ENEA, IPP-Garching, IST-Portugal, FOM, FZJ, RFX, OAW, VR, EFDA-CSU - coordinated by X. Litaudon (Leader) and I. Voitsekhovitch (Deputy) • Suites of codes involved: ASTRA, CRONOS, JETTO, TRANSP, SANCO, SOUL 1D, EDGE2D, EMC3-EIRENE, MISHKA, METIS, HELIOS. ETS (European Tokamak Solver) at the user test phase. • Close collaboration with IO, ITPA groups (T&C and IOS) and experimentalists (JET, AUG, Tore Supra)

  4. Scientific activities: • Activity-1 : Support Validation of the ETS • Activity-2 : Developing and validating plasma scenarios: simulations for existing devices • Activity-3 : Support to predictive scenario modelling for future devices (ITER , JT60SA, etc)

  5. Validation of transport models • Multi-machine database for modelling: AUG, JET, Tore Supra. DIII-D in collaboration with T&C ITPA group. Operational space: dIpl/dt=0.19-0.36 (JET)-0.7 (AUG)-0.8(TS) MA/s, n/nGW=0.2-0.4, q95=3-5(TS), Paux= 0.7(TS) -10 MW: ICRH, NBI, LHCD, ECCD • Tested models: scaling-based model with prescribed radial shape of e = i, semi-empirical models: Bohm-gyroBohm and Coppi-Tang; GLF23 G.M.D. Hogeweij et al, EPS 2010 5 s Te keV 11 s 0.6MW of ECCD (at =0.3) applied from 0.5 till 3.5 s. Profiles at 1 s (halfway the Ip ramp up) OH Ip ramp up phase of JET pulse 71827 Other slices? Difs btw central TS&ECE?

  6. Benchmarking of Coppi-Tang model in ASTRA & CORSICA for DIII-D OH current ramp up discharge with diagnostic beam blips Tom Casper, Irina Voitsekhovitch, ISM WS Nov 29- Dec. 3 2010, Culham ASTRA CORSICA 1.4 s 0.7 s Sqrt(tor flux) • implementation: CORSICA = 2.5ASTRA = 2.5*CT as defined in [Jardin et al NF 1993]. The multiplier 2.5 is used for OH and L-mode only • input data: different ne(r) – more peaked profiles in CORSICA • results: better agreement than previously, but Te is still different. Different POH(r)

  7. Validation of transport models - summary • Summary for transport models - empirical scaling-based: the optimal agreement between experiment and simulations is obtained using either H96-L = 0.6 or HIPB98 = 0.4. - Bohm-gyroBohm: good predictive capability for JET discharges with central heating, over-predicts Te in discharges off-axis heating. OH discharges: predictive accuracy varies depending on q evolution - GLF23: accurate predictive capability in NBI heated plasmas at low power, but less accurate at high power • Coppi-Tang model: - 8Coppi-Tang for OH plasmas, (4.7-4.9)Coppi-Tang for NBI and ICRH heated discharges [I. Voitsekhovitch et al, PPCF 2010] – better agreement with these results when the factor 2.5 has been taken into account, but still a larger multiplier is needed to match the JET discharges

  8. Current diffusion I. Jenkins et al EPS 2010 • I. Jenkins et al [EPS 2010]: early MSE measurements (@~1s) after the breakdown at JET AT scenario: too fast reduction of q0 • G.M.D. Hogeweij et al [], I. Voitsekhovitch et al [PPCF 2010] – too rapid reduction of q0 in JET ITER-like discharges with flat Zeff (Zeff2), but possible to match q0 by playing with Zeff profile and using NCLASS • I. Voitsekhovitch et al, coming IOS ITPA: accurate NCLASS prediction of q profile evolution for 3 DIII-D discharges (Zef  1.5) Zef: 5-3 I. Voitsekhovitch, ISM meeting 10.11.2010 Rgeo from ONETWO, matched plasma volume, data JET 72823 (LH), 5s

  9. li simulations • li simulations with different transport models [F. Imbeaux et al, ITPA 2010] • Sensitivity study by Joerg: li is highly sensitive to edge q, while even significant changes in the central part of q-profile are not necessarily visible in li li(3)=1.11 (solid), 1.26 (dashed) li(3)=1.248 (solid), 1.263 (dashed) ? JET ohmic shot 71827: the plasma current is ramped up to 2.5 MA in 10 s. Te profils are shown at 5 s

  10. Projections to ITER: sensitivity to transport models G.M.D. Hogeweij et al, EPS 2010 I. Voitsekhovitch et al, PPCF 2010: ECRH heated current ramp up GLF23, BgB time=80 s GLF23, BgB Te0 Ti0 OH ramp-up phase with ne/nGW=0.25: profiles of Te, at 100 s (endof the Ip ramp-up), as calculated by 2 transport models, under different assumptions regarding Te(edge) and ne profile shape. time=80 s Scan in ECRH power and power deposition at ne/nGW=0.5

  11. ISM work in progress: • Modelling of current ramp up for JET HS • Optimisation of current ramp up for ITER HS (G.M.D. Hogeweij et al, EPS 2011) • Current ramp up simulations for DIII-D and comparison with JET [I. Voitsekhovitch et al, IOS ITPA group meeting, April 11-14 2011 Place for nice figure with recent results

  12. Publications used in this talk: • Hogeweij G.M.D., et al, Controlled Fusion and Plasma Physics (Proc. 34th Eur. Conf.,Dublin, Ireland, 2007) • V. Parail et al Integrated modelling o ITER reference scenarios, Nucl. Fusion 49 (2009) 075030 3. Hogeweij G.M.D., Citrin J., Garcia J., et al, Current ramp-up in tokamaks from present experiments to ITER scenarios, Controlled Fusion and Plasma Physics (Proc. 37th Eur. Conf.,Dublin, Ireland, 2010), CD-ROM file P1.1041 4. Imbeaux F, Basiuk V, Budny R, et al, Current ramp-ups in tokamaks: from present experiments to ITER scenarios, 23rd IAEA Fusion Energy Conference (ITR/P1-20), Daejon, Republic of Korea, October 10-16th 2010, to be submitted to Nuclear Fusion 5. I. Voitsekhovitch et al, PPCF 2010 6. I. Jenkins et al EPS 2010

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