Prospect of a High Performance, High Radia5on, Steady-‐State Scenario for CFETR
Vincent Chan1,2, Jiangang Li3, Yuanxi Wan1 and the CFETR Physics Team
1 USTC 2 General Atomics
3 ASIPP
Presented at the 4th IAEA Demo Workshop Karlsruhe, Germany Nov 15-18, 2016
1
- Complementing ITER
- Demonstration of fusion energy
production (50-200 MW for Phase I)
- Demonstration of high duty factor, 0.3
– 0.5
- Demonstration of tritium self-
sufficiency with TBR > 1
- Exploring options for DEMO blanket
and divertor solution
- Solution for easy remote
maintenance of in-vessel
components
CFETR Shares Many Characteristics with DEMO
2
Steady-State with High Duty Cycle is Key to Meeting CFETR Mission
3
Metrics ITER CFETR Phase 1-2 DEMO
Neutron wall loading (MW/m
2)
~0.5 0.4 – 2.0 2.0 – 4.0
Life of plant fluence (MW-yr/m
2)
0.2 – 0.4 1.2 – 10 10 – 34
Qfus
5 – 10 3 – 15 10 – 40 Plasma performance βN
2-3 2-4 4-6
Longest plasma duration (s) 10
2 – 10
4 10
5 - 10
6 10
7
Total availability 2% – 5% 30% – 50% 50% – 85% Tritium breeding TBR << 1 TBR≥ 1 TBR > 1 P
Heat/A
wall MW/m2( ) ~ 0.2 0.2 – 0.4 0.8 - 1.0
!
0D System Code Used to Scope out CFETR Baseline and Advanced Scenarios
B. Wan, Plasma Science IEEE, 42 (2014) V. Chan, NF 55 (2015) 4
Does not iden*fy specific steady-‐state scenario
Paths to Steady-State Have Experimental Basis
5
Projec5ons From Experiments
Reverse Shear
Hybrid Mode
F.Turco, POP 2015
S.Y. Ding, APS invited talk 2016
ELM control Radia5ve divertor
Challenge: -‐ High fbs -‐ qmin control
Challenge -‐ Flux pumping? -‐ Avoid 2/1
• 0D system code has missing physics
- Pedestal contribution
- Physics-based transport i.e. only assumes H factor
- Profile information and stability
- Achievable βN and fbs
• IM informs key engineering design requirements
- H&CD, Divertor heat and particle fluxes
- Plasma control
• Critical to CFETR diagnostics design and operation
Integrated Modeling (IM) Used to Quantify Reverse Shear (RS) Scenario and Connect with Engineering Design
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• Physics code suite - TGYRO with NEO and TGLF transport; EPED - ONETWO/NUBEAM/TORAY/GENRAY for sources and sinks;
Ip evolution - EFIT for equilibrium; GATO, ELITE, BOUT++, NIMROD, Nova-
K for stability - SOLPS and OEDGE/DIVIMP for SOL and divertor • Evolving electron density, Te and Ti, and momentum - D&T/He/impurity profiles same as ne and obey quasi-
neutrality - Boundary conditions at pivot point ~ top of pedestal • SOL solution matches core parameters at pivot point
Physics-Based Models and Modeling Assumptions
7
OMFIT Framework Facilitates Self-Consistent Integrated Scenario Development
O. Meneghini, POP 23 (2016) 8
Self-Consistent Transport, Equilibrium and Pedestal: Fully Non-Inductive RS Solution
9
Characteris5cs: - Strong reverse
shear - qmin > 2 - Moderate ITB
forma*on
Optimization of Electron Cyclotron Frequency and Launch Location
E. Poly, Nucl. Fus. 53 (2013) 10
ECCD for controling qmin
Optimization of Neutral Beam Energy
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• NB has reasonable CD efficiency and is efficient in providing plasma rota*on for good confinement
• NB launch angle is constrained to avoid both large shine through and edge hea*ng.
Use of a Two-NB Strategy
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• Fixed high energy NB at 300 keV; op*mize low energy NB • 50 keV NB yields the highest Q and lowest edge hea*ng
Confinement Factor Responsible for Differences between OD and 1.5D Predictions
13
H98=1.3 is not achievable even with NB rota*on for baseline case
R=5.7m BT=5T
Pedestal Collisionality has Significant Impact on Fusion Gain
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• Keeping pedestal pressure fixed, pedestal density is varied • Density increases, DPF unchanged -‐> Q increases significantly • Higher pedestal collisionality might also benefit ELM control PDM=pedestal density mul*plier DPF=density peaking factor
Turbulence Responsible for Weak Density Profile Change with Pedestal Collisionality
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TEM and ITG turbulence influence par*cle transport in opposite direc*ons resul*ng in weaker profile change
RF Dominated Steady-State Scenario is Another Option
16
NB competes with Tri*um Blanket for port space
Higher BT CFETR (R=6.7m, BT=6T) has Higher Fusion Gain
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• Confinement improves with larger R and BT ⇒ Lower CD power and higher fusion gain
• Higher βP => higher bootstrap fac*on • n/nGW = 0.8
Phase I
Agreement of TGYRO/TGLF/NEO with Experiment Improves with Lower q95
J.T. McClenaghan, APS-‐DPP 2016 C.K.Pan, APS-‐DPP 2015 18
q95=9
q95=6=qCFETR
Ti
CFETR Baseline Stable to Ideal MHD in the Core, Unstable to ELMs
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- Unstable modes driven by strong pedestal gradient
- Low n modes stabilized by wall at r/a=1.2
Helium Fraction Cannot Exceed 0.2 in Order to Meet CFETR Pfus Target
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PNB (MW)
PRF (MW)
Pa (MW)
Pcyc,Pbres,Pline(MW) βN H98 Q τE
(s) Ne0,nDT0 Te0,Ti0 (KeV)
fHe=0.05 52.5 10.1 34.9 5.2,4.5,6.7 1.93 1.04 2.79 1.73 7.49,6.44 28.0,25.3
fHe=0.1 58.0 10.1 21.9 3.8,4,4,6.4 1.62 0.92 1.61 1.60 6.94,5.42 24.9,23.2
fHe=0.15 59.5 10.1 18.2 3.7,4.6,6.7 1.58 0.92 1.31 1.63 7.04,4.9 23.8,23.0
fHe=0.20 62.5 10.1 12.7 3.2,4.7,6.7 1.47 0.88 0.88 1.57 6.81,4.15 22.2,22.0
Impurity Transport Profile Determined Using TGYRO
B. Grierson, APS-‐DPP (2015) 22
Γ imp = −Dimpnimp
aa
Ln_ imp+Vimpnimp
Impurity profile obtained from TGYRO assuming no impurity source in core nimp (r) = nimp (rpivot )exp(
Vimp (x)Dimp (x)rpivot
r
∫ dx)
Argon impurity profiles with different effec*ve charge Zeff.
Fusion Performance Improves before Dropping Off with Increasing Zeff
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PNB (MW)
PRF (MW)
Pa (MW)
Pcyc,Pbres, Pline(MW)
PLOSS/PTOT
H98 Q fbs τE(s) Ne0,nDT0
Te0,Ti0 (KeV)
Zeff=1.52 53.7 10.1 19.5 3.1,3.2,4.3 12.7% 0.86 1.44 35.5% 1.48 6.99,5.58 22.1,20.2
Zeff=1.89 53.5 10.1 21.8 3.8,4,4,6.4 17.1% 0.92 1.61 37.2% 1.60 6.94,5.42 24.9,23.2
Zeff=2.11 54.0 10.1 24.1 4.3,5.1,7.9 19.6% 0.96 1.76 39.6% 1.66 7.09,5.48 25.8,24.4
Zeff=2.35 55.3 10.1 24.5 4.3,5.8,9.5 21.8% 0.98 1.75 40.3% 1.68 7.07,5.45 25.6,24.5
Zeff=2.78 56.1 10.1 25.2 4.5,7.0,12.0 25.7% 1.01 1.76 42.1% 1.76 7.10,5.32 26.8,26.3
Zeff=3.20 57.6 10.1 23.3 4.3,8.1,14.4 29.5% 1.00 1.58 42.3% 1.78 7.02,5.08 25.2,25.2
Zeff=3.67 59.9 10.1 23.1 4.9,10.0,17.1 34.4% 1.00 1.44 43.7% 1.78 6.99,4.88 25.9,25.6
Confinement Trend with Zeff is Consistent with Experimental Observation
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G. Mckee, PRL (2000)
R. Dominguez, NF (1993)
Consistent Boundary Coupling Demonstrated
26
Assumed diffusion coefficients
Edge hea5ng not included
Heat flux decay width in SOL similar to scaling law
A Steady-State, High Performance, High Radiation CFETR is Demonstrated
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Phase I Phase II Qfus 3.0 14.9 Pfus (MW) 169 811 Ip (MA) 7.6 10 Bootstrap frac5on fbs (%)
64 84
βN 1.9 3.2 H98 1.3 1.3 NB/EC Power (MW) 36/20 35/20
Neutron wall loading (MW/m2)
0.19 0.92
Divertor heat load Pdiv/R (MW/m)
10.4 25.8
Ion frac5on nD/nT/nHe/nAr
0.43/0.43/ 0.05/0.003
0.43/0.43/ 0.05/0.003
Ra5o to Greenwald Limit
.83 1.03
- R=6.6m, BT=6T - 2 NBs: 100/500 keV - Addi*onal fueling
needed for phase II
- High performance, radia5ve core compa5ble with detached divertor
- Performance op5mized using NB and pedestal control - Both NB-‐dominated and RF-‐dominated op5ons are available
- A broad opera5on range in βN and βp, stable with wall at r/a=1.2 - Radia5on in the core acceptable up to Zeff ~ 3.0 - Helium dilu5on fHe cannot exceeds 0.2 to meet Pfus target
Future work will focus on Phase II op5miza5on of the R=6.7m CFETR consistent with steady-‐state and a radia5ve divertor solu5on
Conclusion
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A reverse-shear, steady-state scenario with performance that meets the CFETR mission has been demonstrated
Acknowledgement
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Key contributors: J.L. Chen, X. Jian, D. Zhao, L. Lao, C.K. Pan, Z.Y. Li, N. Shi, X.J. Liu, Y.F. Zhou, S.F. Mao, G.Q. Li, P. Zhu, G. Zhuang, M.Y. Ye We are grateful to GA, PPPL, Wisconsin, LLNL, U. York, MPG-‐IPP and U. Toronto for the use of their physics code suites
• Safety factor and q95
• Rotation profile
• Pedestal collisionality
• Operational space in β
• Radiative core compatible with divertor
Control Aspects in Optimizing CFETR Performance for Reverse Shear Scenario
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TGYRO Flux Convergence Indicative of Transport Steady-State
J. Candy, POP 16 (2009) 33
All transport channels are evolved to steady-‐state
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