ADT08/09

Update on Self-Consistent Plasma Modeling of ARIES Baseline Design Points

ARIES Team Meeting

Bethesda Md

April 04 2011

A.D. Turnbull,

R. Buttery, M. Choi, L.L Lao,S. Smith, H. St John

General Atomics

ADT08/09

Approach, Optimization, and Recent Progress

• Proposed approach:- Outline- New features

• Optimization procedure:- Physics optimization- Code linkages

• Progress:- Reconstructed ARIES-AT Base configuration with added H-mode

pedestal:o EFIT calculation reproduced 2000 equilibrium

- Run ONETWO calculation to obtain profiles of ne, ni, Te, Ti, current density, and bootstrap current:o Using density and temperature profiles from Jardin and Kessel

2006- Simulated LHCD and ICRF to make up the shortfall in current density

• Main Results:- LHCD can provide up to 0.63 MA for ne(0) ~ 3 x 1020 m-3

- LHCD efficiency is poor at higher densities • Future plans

ADT08/09

Proposal to Perform a Self-Consistent Analysis of ARIES Design Points

• Similar analysis was done in the past for ARIES designs but:- Design points have been updated with improved Systems

Code modeling- Understanding of physics issues has also evolved

considerably:o Particularly pedestal modeling and interaction with the

core• Analysis will involve:

- Coupled equilibrium, transport, current drive, fuelling, and stability calculations to obtain a steady state solution

- In a self consistent simulation using:o Latest core transport modelso Coupled to edge pedestal models

The simulation would use the same tools as used to model DIII-D and FSNF, providing a consistent up-to-date set of

models and tools across the spectrum of current and planned facilities

ADT08/09

Proposal is Intended to Repeat Previous 2000 Effort For ARIES-AT With Improved Tools and

Understanding • New optimized target configuration• Self consistent steady state solution• Transport model TGLF in place of GLF23:

- Real shaped geometry instead of GLF23 shifted circle model• Self consistent H-mode pedestal:

- Realistic pedestal height and width predictions with EPED1• Full-wave Lower hybrid modeling• Improved resistive wall stability understanding:

- Stabilization at low rotation- Role of error fields in braking at low rotation- New angular momentum transport models

• Key technical issue is that core transport is stiff:- Largest leverage to improving confinement is from increasing

pedestal height- Conversely, H-mode pedestal and ELM physics depends

crucially on the heat and particle fluxes coming from the core

ADT08/09

Optimization Procedure

• Aim to use IMFIT to start with for the core loop of transport self consistently optimized with heating and current drive:- Re compute EFIT equilibria as needed

• Incorporate a pedestal optimization:- EPED1 model to predict pedestal height and width given pedestal

optimization:- Initialize with N = 5.7

- Check ideal stability with DCON or GATO?- Optimize to converge to maximum stable N

• q profile optimization:- Adjustment of q profile to improve stability and current drive

potential- Step will need judgement rather than automation

• Shape and size optimization:- Elongation, triangularity and aspect ratio- Size adjustments as needed

ADT08/09

Physics Overview of Optimization Logic

First guess: previous ARIES + pedestal, pass through H&CD & force balance

Heat & current drive Transport solutionONETWO & GENRAY to align profiles

optimization: vary pressure to optimize stabilityDCON or GATO codes

q profile optimization: to improve transport & stabilitychanges in H&CD deposition

Shape optimization: vary elongation, triangularity & aspect ratio. Ultimately change size to ensure

target performance is reached

Re-EPED when changesRe-EFIT at every stage

ADT08/09

Code Linkage Overview of Optimization Procedure

• IMFIT code structure

ADT08/09

Base Line ARIES H-mode Case From 2000 Study

• ARIES H-mode cross section:

• q profile:

ADT08/09133-09/MC/

Previously Optimized ARIES Lower Hybrid Heating and Current Drive Scenarios Using

CURRAY • Aimed to drive non-inductive off-axis current in 0.8 <ρ< 1.0– (S.C. Jardin, Fusion Engineering and design (2006))

• Two scenarios studied with different density:– 4 or 5 wave spectra of LH grills, each centered at a different N//, were determined to

have relatively broad profile

Freq(GHz)

N// θ Power (37 MW)

I/P (A/W)

3.6 1.65

-90 3.06 0.053

3.6 2.0 -90 4.40 0.049

3.6 2.5 -90 8.22 0.039

3.6 3.5 -90 8.87 0.024

2.5 5.0 -90 12.39 0.013

Freq(GHz)

N// θ Power(20 MW)

I/P (A/W)

4 1.7 -90 2.94 0.057

4 2.0 -90 3.24 0.052

4 2.5 -90 5.43 0.041

4 4.0 -90 8.17 0.021

ne(0)=2.93×1020 m-3, Te(0)=26.3keV, Zeff=1.9

ne(0)=2.74×1020 m-3, Te(0)=28.2 keV, Zeff=2.0

Scenario 1

Scenario 2

ADT08/09

Scenario 1 Studied Using Initial Density and Temperature Profiles From Jardin 2006 Fusion

Engineering and Design

Electron

D and T

Normalized toroidal flux Normalized toroidal flux

Te=TD=TT

Zeff=1.69

ne(axis) = 5.0x 1020 m-

3

• Modified to include H-mode edge density pedestal but Te set to be consistent with original pressure from 2006 published result

T(keV) n

(1013 cm-

3)

ADT08/09

For Scenario 1 GENRAY Predicts 0.63 MA Total Driven Current From Lower Hybrid System

Normalized toroidal flux

Grill

f GHz

N// θ Power (37 MW)

I/P (A/W)

1 3.6 1.65

-90 3.06 0.013

2 3.6 2.0 -90 4.40 0.020

3 3.6 2.5 -90 8.22 0.024

4 3.6 3.5 -90 8.87 0.021

5 2.5 5.0 -90 12.39 0.010

LHC

D d

riven

cu

rren

t (A

/cm

2)

Total

grill1grill2grill3grill4grill5

GENRAY

Driven current at higher density is much smaller

ADT08/09

Normalized toroidal flux

Dri

ven

cu

rren

t (A

/cm

2)

LHCDILHCD=0.63 MAICRFIICCD=0.11MA

GENRAY

• ICCD System:

Additional Current Driven by ICCD System in Core

f = 96 MHz

N//=2.0

P=4.7MW

θ = -15o

ADT08/09

Comparison of Driven Current Profiles from GENRAY with CURRAY Results Show Lower

Current Driven

Normalized toroidal flux

Dri

ven

cu

rren

t (A

/cm

2)

LHCDILHCD=0.63 MAICRFIICCD=0.11MA

GENRAY

LHCDILHCD=1.07 MAICRF

IICCD=0.15MA

CURRAY

• Lower current drive found than in 2006 paper probably due to additional density pedestal in new simulation

ADT08/09

Tools for Self Consistent Optimization of ARIES-AT Design Point Are in Place

• Initial case set up:- Equilibrium with H-mode pedestal reproduced

• Simulated electron and ion densities and temperatures (ONETWO):- Edge density pedestal produced consistent with equilibrium

pressure pedestal- No temperature pedestal

• Current drive from Lower Hybrid and ICCD systems reproduced using GENRAY:- Driven current shortfall compared with 2006 CURRAY results- Presumably due to H-mode pedestal

ADT08/09

Future Steps Will Complete Self Consistent Optimization of ARIES-AT Design Point

• Consistent pedestal included:- Both Temperature and density modified to reproduce H-mode

pedestalso Consistent with equilibrium H-mode pressure pedestal

- Equilibrium pedestal modified for consistency with peeling-ballooning (ELM) stabilityo EPED1 model to provide pedestal height and width for given

pedestal pol

• Self consistent steady state scenario iteration:- Heating and current drive optimization using TGLF transport

mode- Pedestal optimization for pol consistent with transport

simulation and EPED1 model• Iteration on , q profile, and ultimately cross section:

- Varied around design point as needed- Resistive wall mode stability considered

ADT08/09

Backup slides

ADT08/09

Case1 : Plasma Density and Temperature Profiles Based on C.E. Kessel’s Paper

Electron

D and T

Den

sity

(1

01

3 c

m-3)

Normalized toroidal flux Normalized toroidal flux

Tem

pera

ture

(keV

)

Te=TD=TT

Ref) C.E. Kessel, Fusion Engineering and design (2006)

Zeff=1.69ne(axis) = 5.0x 1020 m-3

ADT08/09

Case1 : High Density Profile with N//s and Powers of Scenario 1 Predicts Small CD Efficiency

Normalized toroidal flux

Total

grill1grill2grill3grill4grill5

Grill

f GHz

N// θ Power (37 MW)

I/P (A/W)

1 3.6 1.65

-90 3.06 0.0008

2 3.6 2.0 -90 4.40 0.0088

3 3.6 2.5 -90 8.22 0.0084

4 3.6 3.5 -90 8.87 0.0015

5 2.5 5.0 -90 12.39 0.0027

LHC

D d

riven

cu

rren

t (A

/cm

2)

• Grill 5 with N//=5 seems to produce too much current near plasma edge

GENRAY

Total driven current by LH is 0.15 MA

ADT08/09

LHCD Driven Current Profiles from GENRAY and CURRAY

Normalized toroidal flux

LHC

D d

riven

cu

rren

t (A

/cm

2)

Case 2ILHCD=0.63 MA

Case 1ILHCD=0.15 MA

GENRAY CURRAY

ne(0)=2.93×1020 m-3, Te(0)=26.3keV

ILHCD=1.07 MA