Podesta, Mario

Testa, Duccio

Infoscience - École polytechnique fédérale de Lausanne

Status and plans for Joint Experiment EP-8  Validation of Neutral Beam Current Drive and projections to ITER M. Podestà – NSTX-U, USA D. Testa – TCV, Lausanne CH C. Hopf, B. Geiger – ASDEX-U, GE D. Keeling – MAST, UK C. Collins, L. Bardoczi, W. Heidbrink – DIII-D, USA A. Cappa – JT-II, Spain   20th ITPA Topical Group on Energetic ParticlesITER HQ, Cadarache - FranceSeptember 23-25, 2018NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Goals of JEX EP-8 •  Assess NB-CD efficiency vs. NBI parameters –  Include conditions for which EP behavior departs from ‘classical’ •  Develop/validate modeling tools to predict NB-CD in future devices (ITER and DEMO)  –  Include tools to account for ‘non-classical’ effects –  Consider enhanced EP transport by instabilities, microturbulence 2 NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Progress in last ~6 months: extending modeling tools to low-f instabilities •  NSTX/NSTX-U –  Analysis of sawtoothing plasmas continues •  Goal: improve sawtooth model in TRANSP –  Started dedicated activity on NTM, fishbone, kink modeling •  Goal: develop “self-contained” module for TRANSP –  Progress in development, benchmark of Quasi-Linear model RBQ1D •  DIII-D –  Progress in diagnostics (see M. VanZeeland’s talk) –  Recent experiment on “AE mitigation in high-qmin discharges” •  Goal: explore mitigation/suppression techniques •  Assess predictive capabilities of reduced EP transport models (US JRT 2018) •  Analysis started –  Progress in validating “kick model” for NTMs •  Goal: develop self-contained module for TRANSP 3 [Heidbrink, IAEA-EP 2017][Heidbrink, US TTF 2018][Bardoczi, US TTF 2018][Kim, IAEA-TCM-EP 2017][Liu, IAEA-TCM-EP 2017][Podestà US TTF 2018]NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Progress in last ~6 months: New experiments, analysis ongoing •  ASDEX-U/TCV (MST1 programme) –  High-qmin scenarios with high NI fraction on AUG –  Preliminary results: good agreement between measured & simulated MSE, Vloop •  Neoclassical, in spite of strong MHD activity,  –  However: enhanced EP transport required to match neutrons, Wmhd, FIDA •  Results in disagreement for MSE, current! –  See B. Geiger’s presentation •  MAST-U: plans unchanged from previous meeting –  Experimental programme coordinated within EU-MST1 –  Fast Ions and Current Drive studies are prominent part of it 4 NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Progress in last ~6 months: Experimental data available, modeling tools needed •  JT-II –  Database on NBCD available from past years –  No new experiments in last ~year (fixing technical issues) –  Analysis of experimental data starting –  Main issue: lack of modeling tools! •  Need to improve maturity of modeling tools for NBCD to same level as those available for axi-symmetric counfigurations 5 NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Coordinated NSTX-U/DIII-D effort has started to understand & model EP transport by NTMs Leverage work by Poli & Fredrickson to include NTM stability model in TRANSP 6 [Heidbrink et al. IAEA-TCM-EP 2017]ExperimentmodelingTRANSPOngoing validation of “kick model” with NTMs(L. Bardoczi, DIII-D)Goal:predictive model for EP transport by NTMsNSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)•  NB current redistribution depends on NTM spectrum –  e.g. core peaking vs broadening predicted for 2/1 vs 3/2 NTMs  •  NTM island width from measurements •  Reproduce neutron rate, stored energy Example: interpretive TRANSP analysis, no free parameters 7 (L. Bardoczi, DIII-D – US TTF 2018)NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Plans •  Applying new modeling tools for EP transport by low-f instabilities –  Assess resulting NBCD degradation –  Assess synergy between low-f modes and AEs •  Working to make modeling tools (kick model) available to broader community •  Assessment of predictive capabilities would benefit from coordination with ITPA IOS –  Joint meeting in the near future (1day overlap)? •  Need quantitative NBCD modeling tools for non-axisymmetric configurations! 8 NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Backup slides 9 NSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Continuous progress in NB-CD database and analysis tools •  NSTX/NSTX-U/DIII-D –  Database on NB-CD expanded –  Focusing on identification of “critical parameters” for reliable, quantitative CD predictions •  ASDEX-Upgrade, TCV –  Progress in experiments with MSE, FIDA data with NBI –  Analyzing discharges with high non-inductive current fraction, look for effects of instabilities on NB-CD performance > Converging to similar methodology: 10 constrained simulationsexperiments predictionsNSTX/NSTX-UDIII-D AUG/TCVcomparison withexp’t dataNSTX-U 20th ITPA-EP meeting – Status of Joint Experiment on NB-CD,  M. Podestà  (May 2018)Open issue: relax constraints in TRANSP simulation degrades prediction accuracy 11 classical – input equclassical – predict equ/2kick model – input equkick model – predict equ/2>  Remove additional constraints in TRANSP simulations, check agreement with “reference” run •  Unconstrained Vsurf leads to similar NB-driven current profile, but “large” discrepancy in predicted q-profile •  Ongoing work: assess role of computed resistivity  [F. M. Poli, D. Kim] 

Validation of Neutral Beam Current Drive and projections to ITER

http://infoscience.epfl.ch/record/264818/files/Podesta_status_NBCD_JEX_EP8_20180521.pdf

Validation of Neutral Beam Current Drive and projections to ITER

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Infoscience - École polytechnique fédérale de Lausanne