# Presentation: 454437

## Integrated Modeling and Simulations of ITER Burning Plasma Scenarios

- C. E. Kessel, R. V. Budny, K. Indireshkumar, D. Meade
*Princeton Plasma Physics Laboratory*
**IEA Large Tokamak Workshop (W60) Burning Plasma Physics and Simulation**
**Tarragona, Spain**
**July 4-5, 2005**

## Integrated Scenario Development for ITER Advanced Operating Modes

**Goals**
**Provide discharge simulations for self-consistency of plasma configurations**
**Identify impact of uncertain physics**
**Identify operating space within device/engineering limitations, and required upgrades**
**Define auxiliary systems requirements**
**Examine plasma control issues (equilibrium, stored energy, current profile)**
**Examine physics/engineering interfaces (PF coils, divertor)**
**Examine detailed physics modeling outside scope of 1.5D simulations, feeding back constraints for 1.5D**
**Provide experiment/theory comparison/verification within an integrated physics simulation**

## Integrated Modeling of ITER Hybrid Burning Plasma Scenarios

**0D systems analysis to identify operating space within engineering contraints**
**1.5D discharge simulations**
**Energy transport (GLF23)**
**Heating/CD**
**Free-boundary equilibrium evolution/feedback control**
**Other control; stored energy, f****NI****, etc.**
**Energy transport experimental verification**
**Ideal MHD analysis**
**Offline heating/CD source analysis**
**Offline gyrokinetic transport simulations (Budny)**
**Fast particle effects and MHD (Gorelenkov)**
**Particle transport/impurity transport**
**Integrated SOL/divertor modeling**
**Non-ideal MHD, NTM’s**

## 0D Systems Analysis Identifies Device Constraints for Scenario Simulations

**ITER’s Primary Device Limitations That Affect Scenarios**
- Fusion power vs pulse length **---->  heat rejection system**
- 350 MW for 3000 s
- 500 MW for 400 s
- 700 MW for 150 s **----> (maximum P****fus**** cryoplant limits)**
- Divertor conducted heat load, maximum > 20 MW/m2, nominal 5-10 MW/m2 **----> allowable divertor heat load**
- Radiation from plasma core and edge, PSOL = (1 - fcorerad) Pinput
- Radiation in divertor and around Xpt, Pcond = (1 - fdivrad) PSOL
- Radiation distribution in divertor channel, impurities, transients
- Volt-second capability **----> PF coil current limits**
- Approximately 260-280 V-s
- First wall surface heat load limit (not limiting for normal operation)
- Duty cycle, tflattop/(tflattop + tdwell) **----> cryoplant for SC coils**
- Limited to about 25%

**What device upgrades are required for advanced operating modes, and are they major or minor upgrades?**

## Pursuing 1.5D Integrated Modeling of ITER with TSC/TRANSP Combination

_**TRANSP**_
- Interpretive
- Fixed boundary Eq. Solvers
- Monte Carlo NB and  heating
- SPRUCE/TORIC/CURRAY for ICRF
- TORAY for EC
- LSC for LH
- Fluxes and transport from local conservation; particles, energy, momentum
- Fast ions
- Neutrals

**Plasma geometry**
**T, n profiles**
**q profile**

**Accurate source profiles fed back to TSC**

_**TSC**_
- Predictive
- Free-boundary/structures/PF coils/feedback control systems
- T, n, j transport with model or data coefficients (, , D, v)
- LSC for LH
- Assumed source deposition for NB, EC, and ICRF: typically use off-line analysis to derive these

- both codes have models for bootstrap current, radiation, sawteeth, ripple loss, pellet fueling, impurities, etc.

**TSC evolution treated like an experiment**

## 1.5D ITER Hybrid Simulations Integrate Transport, Heating/CD, and Equilibrium

-  **Density evolution prescribed, magnitude and profile**
** ****2% Be + 2% C + 0.12% Ar for high Z****eff**** cases**
** ****GLF23 thermal diffusivities, no rotation stabilization, and with rotation stabilization  (plasma rotation from TRANSP assuming ************ = ********i****)**
** ****Prescribed pedestal height and location amended to GLF23 thermal diffusivities**
** ****Control plasma current, radial position, vertical position and shape**
** ****Plasma grown from limited starting point on outboard limiter, early heating required to keep q(0) > 1, keep P****heat ****< 10 MW**
** ****Control on plasma stored energy, P****ICRF**** in controller, P****NB**** not in controller since it is supplying NICD**

## ITER Hybrid with GLF23 Requires High n/nGr, High Tped to Reach N ≈ 3

- Shape control points

- IP = 12 MA
- BT = 5.3 T
- INI = 7.75 MA
******N**** = 2.90**
**n/n****Gr**** = 0.93**
- Wth = 450 MJ
**H****98**** = 1.56**
**T****ped**** = 9 keV**
- ∆rampup = 150 V-s
- Vloop = 0.042 V
- Q = 9.43
**P******** = 100 MW**
**P****aux**** = 53 MW**
**P****rad**** = 27 MW**
- Zeff = 2.25
**q(0) < 1, ≈ 0.9**
**r(q=1) = 0.45 m**
- li(1) = 0.8
**t****flattop****V-s**** ≈ 3000 s**

**ITER Hybrid with GLF23 Requires High n/n****Gr****, High T****ped**** to Reach ********N ****≈ 3**

- t = 170 s

- t = 1500 s

- 

## ITER Hybrid Simulation Shows Rapid q(0) Drop, V-s are Low, Long Core Relaxation

**ITER Hybrid Simulation Shows Rapid q(0) Drop, V-s are Low, Long Core Relaxation**

## ITER Hybrid Scenario Needs High Tped for GLF23 w/o and w ExB

**ITER expected to have**
**Low v****rot**** (≈ 1/10 v****rot****DIII-D****)**
**T****i**** ≈ T****e**
**Low n(0)/<n>**
**Present Expts have**
**High v****rot**
**T****i**** > T****e**
**n(0)/<n> > 1.25**
**Direct extrapolation from present Expts to ITER may be optimistic**
**Continuing analysis with ************ = f x ********i**** , higher n(0)/<n>, etc.  **

**v****rot**** from TRANSP with ************ =  ********i**** **

## Using TRANSP Monte Carlo NB and SPRUCE Full Wave/FP ICRF Analysis to Model ITER Hybrid Sources

- IP = 12 MA, PNB = 33 MW, PICRF = 20 MW

**W****th**** = 300 MJ**
**W****th**** = 350 MJ**

**I****NB**** = 2.1 MA**
**I****NB**** = 1.8 MA**

**ICRF Heating**

**NINB Heating/CD**

## Using JSOLVER/BALMSC/PEST2, ... to Analyze Ideal MHD Stability of ITER Hybrid

- Hybrid discharges operate in a N window
- NNTM < N < Nn=1(no wall)
- Hybrid discharges have fNI ≥ 40%, from NBCD on-axis and BS off-axis
- Hybrid discharges prefer q(0) > 1 or small sawtooth amplitude or possibly small r(q=1)

**Examine ****Porcelli sawtooth model in 1.5D simulations**** to determine the sawtooth response to small r(q=1), and local dq/dr and dp/dr**

## Efforts to Benchmark GLF23 Transport in DIII-D 104276 Hybrid Discharge

**Efforts to Benchmark GLF23 Transport in DIII-D 104276 Hybrid Discharge**

**TSC free-boundary, discharge simulation**
**DIII-D 104276 data**
**PF coil currents**
**Te,i(********), n(********), v(********)**
**NB data TRANSP**
**Use n(********) directly**
**TSC derives ********e****, ********I**** to reproduce T****e**** and T****i**
**Turn on GLF23 in place of expt thermal diffusivities**
**Test GLF23 w/o ExB and w EXB shear stabilization**

- t = 1.5 s

- t = 5.0 s

**L-mode, i-ITB**

**H-mode**

## Energy Transport is at Center of Modeling/Projections for ITER

- Whats wrong:
**How is comparing to experiment improving our modeling??** Error are say 20-30% on Te and Ti profiles, and maybe 10% on stored energy
- Multiple models, for example GLF23 and MMM95, will give reasonable agreement on any given experiment, **how good should this be to believe a projection to ITER** (remember ITER-EDA, comparison of transport models in Physics Basis 1999, **what has changed??**)
- What can we do:
- Examine the critical features of transport; external rotation, Te/Ti, safety factor, density peaking, etc. and **test these**
**Apply transport models to difficult expts. C-mod ITB, JT60-U high ********P****, DIII-D/AUG/JET Hybrid and AT discharges....**
**Apply transport model to entire discharge, not a single flattop time-slice**
**Consider what will be present in burning plasma device**

## Integrated Modeling of Burning Plasmas

**Integration includes feeding back numerous offline analyses to constrain the core 1.5D transport modeling**
- 0D analysis for operating space limitations
- Ideal and non-ideal MHD analysis
- Source modeling benchmarks
- Detailed SOL/divertor modeling
- Particle and impurity transport (fueling)
**TSC/TRANSP is being used to improve the 1.5D simulations **of** **burning plasma scenarios on ITER  ---  provides integration of full discharge free-boundary/feedback control and sophisticated source modeling/fast particle treatment
- Energy transport is at the center of 1.5D transport simulations
**Project to ITER with consideration of difference from present expts**.
**Apply theoretical models to difficult experimental cases and for the entire discharge**
- Pedestal projections need to transition from empirical to theory based
- In some areas our integrated modeling needs more effort
**Particle/impurity transport**
- SOL/divertor integrated into core evolution
- Non-ideal MHD