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

R. Budny, C. KesselPPPL

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 Tped in Hybrid simulations– Steady state scenario– Submit equilibria– PTRANSP (come to McCune's talk tomorrow)

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 He33-minority ICRH

– Toroidal rotation predictions

– alpha ash accumulation

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

TRANSP NNBI Steering in ITER

ELMy H-mode

on-axis

off-axisZcenter = -0.4 mat R=5.3 m

INB = 850 kA

Zcenter = +0.15 mat R=5.3 m

INB = 970 kA

Upgrade ICRF Modeling in TRANSP using TORIC Full Wave/FPPRF

Replace SPRUCE with TORIC4Allows mode conversionAllows FWCD analysis

Full wave analysis still combined with Fokker-Planck code

Treat all species including impuritiesFast 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

Compare TORIC and SPRUCE on a He3 minority Hybrid case

TORIC SPRUCE

T 13.9 % 13.2 %D 4.43 2.70He4 0.13 0.16Ar 3.43 0.90Be 1.81 0.39C 0.48 Fast D 0.18 1.30He3 min 30.7 40.3Fast He4 0.52 4.61Elec 44.9 35.9

Lower Hybrid Simulation Code (LSC) Upgraded to Include Trapping and Model

Multi-Lobe Spectra

<j.B

>/<

B**

2>,

A/m

2-T 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

PLH = 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, BT = 5.3 TINB = 0.9 MA, IBS = 2.4 MAPNB = 33 MW, PICRF = 13 MW, P = 82.5 MWPrad = 32.4 MW, Q = 9li(1) = 1.0, r(q=1) = 1.05 m, Wth = 325 MJn(0) = 1.05 x 1020 /m3, n(0)/<n> = 1.05N = 1.73, p = 0.64Te(0) = 26 keV, Ti(0) = 23.5 keVT(0)/<T> = 2.85

H98(y,2) = 0.96Tped = 4.8 keV, Tped

database = 5.4 keV

Zeff = 1.64 (2% Be, 0.12% Ar)<nHe>/<ne> = 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 specificationn(0) = 1.05 x 1020 /m3, n(ped) = n(0), n(=1) = 0.6 x n(0)n(0)/<n> = 1.02ped = 0.925 vs 0.885Tped = 4.0 keV vs 4.8 keV

Simulation of ITER Hybrid Scenario with On-axis NB Steering

IP = 12 MABT = 5.3 TINI = 6.1 MAN = 2.96n/nGr = 0.93n20(0) = 0.93Wth = 450 MJH98 = 1.68Tped = 9.5 keV∆rampup = 150 V-s

Vloop = 0.025 VQ = 11.3P = 102 MWPaux = 45 MWPrad = 28 MWZeff = 2.25q(0) ≈ 0.85 @ 1500sr(q=1) = 0.60 mli(1) = 0.80Te,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) = 0.96 @ t = 1500 s

Te,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 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) = 1.824104M1/3Ip2R-2.1a-0.573.81(1+2)-7/3(1+)3.41nped-1/3(Ptot/PLH)0.144

Sugihara, 2003 ---> 5.4 keV for ELMy H-mode

ITER Steady State Scenario Using NNBI, ICRF and LH

Ip = 8 MA, BT = 5.3 TR = 6.33, a = 1.77, = 1.95, = 0.5IBS = 5.2 MA, ILH = 1.3 MA, INB = 0.95 MAq95 ≈ 6, q(0) ≈ 3.2, li(1) ≈ 0.6n/nGr = 0.95, n20(0) = 0.78, n(0)/<n> = 1.22p = 2.5, N = 3.3, H98 = 1.8Te(0) = 38 keV, Ti(0) = 33 keV, Tped = 3.0 keVramp = 90 V-s

P = 80 MW, PLH = 35 MW, PICRF = 20 MWPNBI = 16.5 MW, Prad = 20.5 MW

Thermal diffusivities are analytic prescriptionsZeff = 1.65, 2% Be, 0.1% Ar, <nHe>/<ne> = 6.9%

ITER Steady State Scenario Using NNBI, ICRF and LH

LH: n||0 = 1.95, n|| = 0.2,

f = 5 GHz, PLH = 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 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

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