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ITER Standard H-mode, Hybrid and Steady State WDB Submissions

R. Budny, C. Kessel PPPL ITPA Modeling Topical Working Group Session on ITER Simulations PPPL, Princeton NJ, April 25, 2006. ITER Standard H-mode, Hybrid and Steady State WDB Submissions. Outline. Past WDB submissions of ITER plasmas 2 Standard ELMy H-modes 4 Hybrid plasmas

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ITER Standard H-mode, Hybrid and Steady State WDB Submissions

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  1. R. Budny, C. Kessel PPPL ITPA Modeling Topical Working Group Session on ITER Simulations PPPL, Princeton NJ, April 25, 2006 ITER Standard H-mode, Hybrid and Steady State WDB Submissions

  2. Outline • Past WDB submissions of ITER plasmas • 2 Standard ELMy H-modes • 4 Hybrid plasmas • Improved modeling of NNBI, ICRF, LHCD • NNBI steering and footprint • ICRF using TORIC • LHCD with trapped particle corrections and negative lobe • Planned new submissions • New TSC/TRANSP runs with new source models • Study Tped in Hybrid simulations • Steady state scenario • Submit equilibria • PTRANSP (come to McCune's talk tomorrow)

  3. Past Submissions • Standard ELMy H-mode • 10010100 based on D. Campbell circa 2000 • 10020100 based on TSC/GLF23 Temperature predictions • Hybrid plasmas • 20010100 based on TSC/GLF23 with flat density, N ≈ 2.1 • 20020100 based on TSC/GLF23 with flat density, N ≈ 3 • 20030100 based on TSC/GLF23 with peaked density, off-axis • 20040100 based on TSC/GLF23 with peaked density, on-axis • Modeling assumptions • start-up and steady state control • ITER shaped boundary • 33MW NBI + up to 20MW He3-minority ICRH • Toroidal rotation predictions • alpha ash accumulation

  4. Hybrid Scenario Studies • Developed N ≈ 3 hybrid scenario, with Pfusion = 500 MW, n(0) = 0.93x1020 /m3, Tped = 9.5 keV, H98 = 1.6 using GLF23 core energy transport • Q (Pfusion/Paux) increases with Tped • With GLF23 core energy transport requires high Tped (9-10 keV) to obtain N ≈ 3; lower N with lower Tped • Plasma rotation predicted assuming  = I has little effect • Density peaking with assumed density profile actually worsened plasma confinement • GLF23 predicts higher thermal diffusivities in presence of increased density gradients • May need to use GLF23 density transport, although it is known to require an anomalous term to be added

  5. TRANSP NNBI Steering in ITER ELMy H-mode on-axis Zcenter = +0.15 m at R=5.3 m INB = 970 kA off-axis Zcenter = -0.4 m at R=5.3 m INB = 850 kA

  6. Upgrade ICRF Modeling in TRANSP using TORIC Full Wave/FPPRF • Replace SPRUCE with TORIC4 • Allows mode conversion • Allows FWCD analysis • Full wave analysis still combined with Fokker-Planck code • Treat all species including impurities • Fast NB deuterons and alpha treated as equivalent Maxwellians at high T • Are eliminating He3 minority heating to heat 2T • Reduced fHe3/fDT to 0.2% from 2% • PHe3 = 1.8 MW • Pelec = 11 MW • Pions = 7.2 MW • Continuing to optimize the TORIC parameters for efficient computations ELMy H-mode case PICRF = 20 MW 52.5 MHz

  7. Compare TORIC and SPRUCE on a He3 minority Hybrid case TORICSPRUCE T 13.9 % 13.2 % D 4.43 2.70 He4 0.13 0.16 Ar 3.43 0.90 Be 1.81 0.39 C 0.48 Fast D 0.18 1.30 He3 min 30.7 40.3 Fast He4 0.52 4.61 Elec 44.9 35.9

  8. Lower Hybrid Simulation Code (LSC) Upgraded to Include Trapping and Model Multi-Lobe Spectra PLH = 35 MW, f = 5.0 GHz, n||pos = 1.95, n|| = 0.2, n||neg = -3.9, n|| = 0.2 • No trapping, single positive spectral lobe • ILH = 3.2 MA • Trapping, single positive spectral lobe • ILH = 2.0 MA • Trapping, one positive lobe (85%) and one negative lobe (15%) • ILH = 1.56 MA <j.B>/<B**2>, A/m2-T NBCD BS ITER SS mode simulation in TSC /b

  9. Reference ELMy H-mode TSC Simulation Ip = 15 MA, BT = 5.3 T INB = 0.9 MA, IBS = 2.4 MA PNB = 33 MW, PICRF = 13 MW, P = 82.5 MW Prad = 32.4 MW, Q = 9 li(1) = 1.0, r(q=1) = 1.05 m, Wth = 325 MJ n(0) = 1.05 x 1020 /m3, n(0)/<n> = 1.05 N = 1.73, p = 0.64 Te(0) = 26 keV, Ti(0) = 23.5 keV T(0)/<T> = 2.85 H98(y,2) = 0.96 Tped = 4.8 keV, Tpeddatabase = 5.4 keV Zeff = 1.64 (2% Be, 0.12% Ar) <nHe>/<ne> = 4.8% GLF23 core energy transport

  10. Reference ELMy H-mode TSC Simulation

  11. Simulation of ELMy H-mode: Scenario #2 What’s different compared to previous simulation: Density profile specification n(0) = 1.05 x 1020 /m3, n(ped) = n(0), n(=1) = 0.6 x n(0) n(0)/<n> = 1.02 ped = 0.925 vs 0.885 Tped = 4.0 keV vs 4.8 keV

  12. Simulation of ITER Hybrid Scenario with On-axis NB Steering IP = 12 MA BT = 5.3 T INI = 6.1 MA N = 2.96 n/nGr = 0.93 n20(0) = 0.93 Wth = 450 MJ H98 = 1.68 Tped = 9.5 keV ∆rampup = 150 V-s Vloop = 0.025 V Q = 11.3 P = 102 MW Paux = 45 MW Prad = 28 MW Zeff = 2.25 q(0) ≈ 0.85 @ 1500s r(q=1) = 0.60 m li(1) = 0.80 Te,i(0) = 33 keV GLF23 core energy transport

  13. Simulation of ITER Hybrid Scenario with Off-axis NB Steering Mostly the same parameters as the on-axis NB case except: li(1) = 0.74, q(0) = 0.96 @ t = 1500 s Te,i(0) = 30 keV vs 33 keV GLF23 core energy transport

  14. Simulation of ITER Hybrid Scenario with Off-axis NB Steering

  15. High Pedestal Temperature in Hybrid Scenario due to Low Core Confinement • The high Tped identified in Hybrid scenarios, using GLF23 core energy transport, is correlated to targeting a high stored energy ---> N ≈ 3 • Plots of Q vs. Tped vs. Paux show that lower Tped results in lower N • The high pedestal temperature is affecting other factors as well • Lower line radiation due to high T between pedestal and separatrix (or lower volume with T’s that allow high Ar radiation) • Larger ped causes the required Tped, to obtain a given N, • to drop, but also concentrates the bootstrap current into a smaller region and distorts q • We have found that the large resulting jBS at the plasma edge from the high Tped values is generating n = 2-5 peeling modes (did not examine higher n) concentrated near the plasma boundary • How do we determine that the required Tped is too high, and how do we obtain Hybrid scenarios with lower Tped, but otherwise desirable parameters Pped(Pa) = 1.824104M1/3Ip2R-2.1a-0.573.81(1+2)-7/3(1+)3.41nped-1/3(Ptot/PLH)0.144 Sugihara, 2003 ---> 5.4 keV for ELMy H-mode

  16. ITER Steady State Scenario Using NNBI, ICRF and LH Ip = 8 MA, BT = 5.3 T R = 6.33, a = 1.77,  = 1.95,  = 0.5 IBS = 5.2 MA, ILH = 1.3 MA, INB = 0.95 MA q95 ≈ 6, q(0) ≈ 3.2, li(1) ≈ 0.6 n/nGr = 0.95, n20(0) = 0.78, n(0)/<n> = 1.22 p = 2.5, N = 3.3, H98 = 1.8 Te(0) = 38 keV, Ti(0) = 33 keV, Tped = 3.0 keV ramp = 90 V-s P = 80 MW, PLH = 35 MW, PICRF = 20 MW PNBI = 16.5 MW, Prad = 20.5 MW Thermal diffusivities are analytic prescriptions Zeff = 1.65, 2% Be, 0.1% Ar, <nHe>/<ne> = 6.9%

  17. ITER Steady State Scenario Using NNBI, ICRF and LH On-axis NB & ICRF heating LH: n||0 = 1.95, n|| = 0.2, f = 5 GHz, PLH = 35 MW, P+ = 85%, P- = 15%

  18. Results • NB steering and footprint description has been improved in TRANSP for ITER NNBI • Now using TORIC full wave analysis for ICRF heating, replacing the SPRUCE full wave model used before • Upgraded LSC to include trapped particles and established how to obtain multi-lobe model spectra • New results for ITER ELMy H-mode • Find “reasonable” temperature pedestals (4-5 keV) required to reach targeted performance, using the GLF23 core energy transport model • Examined ITER ELMy H-mode Scenario #2 prescription, using GLF23 finding that target parameters are reached • Since the pedestal is prescribed to be at about ped = 0.93, the Tped required to reached the targeted stored energy is lower, 4 keV versus 4.8 keV for ped = 0.88 • Porcelli sawtooth model, which includes fast particle stabilization and a resistive internal kink criteria was applied to the ELMy H-mode

  19. Results • Recalculated Hybrid scenario with updated on and off-axis NB steering • Largely unchanged from previous results • High Tped is required with GLF23 core energy transport model, and low core/edge radiation is an issue for these scenarios • Off-axis NB steering slows the onset of q=1 significantly, but does not remove it, and likely results in an even smaller sawtooth radius compared to on-axis NB steering • Application of Porcelli sawtooth model with hyper-resistivity to the on-axis Hybrid scenario shows that the sawteeth are still unstable, so that even with a smaller sawtooth radius, the sawtooth can not be stabilized • Examination of the off-axis NB steering case will be done next • Steady State scenario has been produced using NNBI, ICRF, and LH utilizing NUBEAM, TORIC, and LSC • Core transport was prescribed analytically, and self-consistent transport models will be applied next • Will continue to pursue feasibility of producing reverse magnetic shear configurations with large qmin radius

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