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

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 T ped in Hybrid simulations –Steady state scenario –Submit equilibria –PTRANSP (come to McCune's talk tomorrow)

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

Hybrid Scenario Studies Developed  N ≈ 3 hybrid scenario, with P fusion = 500 MW, n(0) = 0.93x10 20 /m 3, T ped = 9.5 keV, H 98 = 1.6 using GLF23 core energy transport Q (P fusion /P aux ) increases with T ped –With GLF23 core energy transport requires high T ped (9-10 keV) to obtain  N ≈ 3; lower  N with lower T ped –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

TRANSP NNBI Steering in ITER ELMy H-mode on-axis off-axis Z center = -0.4 m at R=5.3 m I NB = 850 kA Z center = m at R=5.3 m I NB = 970 kA

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 f He3 /f DT to 0.2% from 2% P He3 = 1.8 MW P elec = 11 MW P ions = 7.2 MW Continuing to optimize the TORIC parameters for efficient computations ELMy H-mode case P ICRF = 20 MW 52.5 MHz

Compare TORIC and SPRUCE on a He3 minority Hybrid case TORIC SPRUCE T 13.9 % 13.2 % D He Ar Be C 0.48 Fast D He3 min Fast He Elec

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

Reference ELMy H-mode TSC Simulation Ip = 15 MA, B T = 5.3 T I NB = 0.9 MA, I BS = 2.4 MA P NB = 33 MW, P ICRF = 13 MW, P  = 82.5 MW P rad = 32.4 MW, Q = 9 li(1) = 1.0, r(q=1) = 1.05 m, W th = 325 MJ n(0) = 1.05 x /m 3, n(0)/ = 1.05  N = 1.73,  p = 0.64 Te(0) = 26 keV, Ti(0) = 23.5 keV T(0)/ = 2.85 H 98(y,2) = 0.96 T ped = 4.8 keV, T ped database = 5.4 keV Z eff = 1.64 (2% Be, 0.12% Ar) / = 4.8% GLF23 core energy transport

Reference ELMy H-mode TSC Simulation

Simulation of ELMy H-mode: Scenario #2 What’s different compared to previous simulation: Density profile specification n(0) = 1.05 x /m 3, n(  ped ) = n(0), n(  =1) = 0.6 x n(0) n(0)/ = 1.02  ped = vs T ped = 4.0 keV vs 4.8 keV

Simulation of ITER Hybrid Scenario with On-axis NB Steering I P = 12 MA B T = 5.3 T I NI = 6.1 MA  N = 2.96 n/n Gr = 0.93 n 20 (0) = 0.93 W th = 450 MJ H 98 = 1.68 T ped = 9.5 keV ∆  rampup = 150 V-s V loop = V Q = 11.3 P  = 102 MW P aux = 45 MW P rad = 28 MW Z eff = 2.25 q(0) ≈ 1500s r(q=1) = 0.60 m li(1) = 0.80 Te,i(0) = 33 keV GLF23 core energy transport

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) = t = 1500 s T e,i (0) = 30 keV vs 33 keV GLF23 core energy transport

Simulation of ITER Hybrid Scenario with Off-axis NB Steering

High Pedestal Temperature in Hybrid Scenario due to Low Core Confinement The high T ped identified in Hybrid scenarios, using GLF23 core energy transport, is correlated to targeting a high stored energy --->  N ≈ 3 Plots of Q vs. T ped vs. P aux show that lower T ped 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 T ped, 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 j BS at the plasma edge from the high T ped 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 T ped is too high, and how do we obtain Hybrid scenarios with lower T ped, but otherwise desirable parameters P ped (Pa) =  10 4 M 1/3 Ip 2 R -2.1 a  3.81 (1+  2 ) -7/3 (1+  ) 3.41 n ped -1/3 (P tot /P LH ) Sugihara, > 5.4 keV for ELMy H-mode

ITER Steady State Scenario Using NNBI, ICRF and LH Ip = 8 MA, B T = 5.3 T R = 6.33, a = 1.77,  = 1.95,  = 0.5 I BS = 5.2 MA, I LH = 1.3 MA, I NB = 0.95 MA q 95 ≈ 6, q(0) ≈ 3.2, li(1) ≈ 0.6 n/n Gr = 0.95, n 20 (0) = 0.78, n(0)/ = 1.22  p = 2.5,  N = 3.3, H 98 = 1.8 T e (0) = 38 keV, T i (0) = 33 keV, T ped = 3.0 keV  ramp = 90 V-s P  = 80 MW, P LH = 35 MW, P ICRF = 20 MW P NBI = 16.5 MW, P rad = 20.5 MW Thermal diffusivities are analytic prescriptions Z eff = 1.65, 2% Be, 0.1% Ar, / = 6.9%

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

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 T ped 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

Results Recalculated Hybrid scenario with updated on and off-axis NB steering –Largely unchanged from previous results –High T ped 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 q min radius