1. Update on Self-Consistent Plasma Modeling of ARIES Baseline Design Points
A.D. Turnbull,
R. Buttery, M. Choi, L.L Lao,
S. Smith, H. St John
General Atomics
ARIES Team Meeting
Bethesda Md
April

2. 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:
EFIT calculation reproduced 2000 equilibrium
Run ONETWO calculation to obtain profiles of ne, ni, Te, Ti, current density, and bootstrap current:
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

3. 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:
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:
Latest core transport models
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

4. 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

5. 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 b
b optimization:
Initialize with bN = 5.7
Check ideal stability with DCON or GATO?
Optimize to converge to maximum stable bN
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

6. Physics Overview of Optimization Logic
First guess: previous ARIES + pedestal, pass through H&CD & force balance
Heat & current drive  Transport solution ONETWO & GENRAY to align profiles
Re-EPED when b changes
Re-EFIT at every stage
b optimization: vary pressure to optimize stability DCON or GATO codes
q profile optimization: to improve transport & stability changes in H&CD deposition
Shape optimization: vary elongation, triangularity & aspect ratio. Ultimately change size to ensure target performance is reached

7. Code Linkage Overview of Optimization Procedure
IMFIT code structure

8. Base Line ARIES H-mode Case From 2000 Study
ARIES H-mode cross section:
q profile:

9. 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
Scenario 1
Scenario 2
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
Freq
(GHz)
N// θ
Power
(37 MW)
I/P (A/W)
3.6
1.65
-90
3.06
0.053
2.0
4.40
0.049
2.5
8.22
0.039
3.5
8.87
0.024
5.0
12.39
0.013
Freq
(GHz)
N// θ
Power
(20 MW)
I/P (A/W) 4
1.7
-90
2.94
0.057
2.0
3.24
0.052
2.5
5.43
0.041
4.0
8.17
0.021
133-09/MC/

10. Scenario 1 Studied Using Initial Density and Temperature Profiles From Jardin 2006 Fusion Engineering and Design
Modified to include H-mode edge density pedestal but Te set to be consistent with original pressure from 2006 published result
ne(axis) = 5.0x 1020 m-3 T
(keV) n
(1013 cm-3)
Te=TD=TT
Electron
Zeff=1.69
D and T
Normalized toroidal flux
Normalized toroidal flux

11. For Scenario 1 GENRAY Predicts 0
For Scenario 1 GENRAY Predicts 0.63 MA Total Driven Current From Lower Hybrid System
Grill
f GHz
N// θ
Power
(37 MW)
I/P (A/W) 1
3.6
1.65
-90
3.06
0.013 2
2.0
4.40
0.020 3
2.5
8.22
0.024 4
3.5
8.87
0.021 5
5.0
12.39
0.010
Total
grill1
grill2
grill3
grill4
grill5
LHCD driven current (A/cm2)
GENRAY
Driven current at higher density is much smaller
Normalized toroidal flux

12. Additional Current Driven by ICCD System in Core
GENRAY
f = 96 MHz
N//=2.0
P=4.7MW
θ = -15o
LHCD
ILHCD=0.63 MA
Driven current (A/cm2)
ICRF
IICCD=0.11MA
Normalized toroidal flux

13. Comparison of Driven Current Profiles from GENRAY with CURRAY Results Show Lower Current Driven
Lower current drive found than in 2006 paper probably due to additional density pedestal in new simulation
GENRAY
CURRAY
Driven current (A/cm2)
LHCD
ILHCD=0.63 MA
LHCD
ILHCD=1.07 MA
ICRF
IICCD=0.11MA
ICRF
IICCD=0.15MA
Normalized toroidal flux

14. 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

15. Future Steps Will Complete Self Consistent Optimization of ARIES-AT Design Point
Consistent pedestal included:
Both Temperature and density modified to reproduce H-mode pedestals
Consistent with equilibrium H-mode pressure pedestal
Equilibrium pedestal modified for consistency with peeling-ballooning (ELM) stability
EPED1 model to provide pedestal height and width for given pedestal bpol
Self consistent steady state scenario iteration:
Heating and current drive optimization using TGLF transport mode
Pedestal optimization for bpol consistent with transport simulation and EPED1 model
Iteration on b, q profile, and ultimately cross section:
Varied around design point as needed
Resistive wall mode stability considered

16. Backup slides

17. Case1 : Plasma Density and Temperature Profiles Based on C. E
Case1 : Plasma Density and Temperature Profiles Based on C.E. Kessel’s Paper
Ref) C.E. Kessel, Fusion Engineering and design (2006)
Zeff=1.69
ne(axis) = 5.0x 1020 m-3
Electron
Te=TD=TT
Density (1013 cm-3)
Temperature (keV)
D and T
Normalized toroidal flux
Normalized toroidal flux

18. Case1 : High Density Profile with N//s and Powers of Scenario 1 Predicts Small CD Efficiency
Grill 5 with N//=5 seems to produce too much current near plasma edge
GENRAY
grill1
Grill
f GHz
N// θ
Power
(37 MW)
I/P (A/W) 1
3.6
1.65
-90
3.06
0.0008 2
2.0
4.40
0.0088 3
2.5
8.22
0.0084 4
3.5
8.87
0.0015 5
5.0
12.39
0.0027
grill2
grill3
grill4
grill5
LHCD driven current (A/cm2)
Total
Total driven current by LH is 0.15 MA
Normalized toroidal flux

19. LHCD Driven Current Profiles from GENRAY and CURRAY
ILHCD=1.07 MA
Case 2
ILHCD=0.63 MA
LHCD driven current (A/cm2)
Case 1
ILHCD=0.15 MA
Normalized toroidal flux
ne(0)=2.93×1020 m-3, Te(0)=26.3keV