NSTX-U Status and Plan
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Transcript of NSTX-U Status and Plan
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
NSTX-U Status and PlanMasayuki Ono
NSTX-U Project DirectorPPPL, Princeton University
In collaboration with the NSTX-U Team
Culham Sci CtrU St. Andrews
York UChubu UFukui U
Hiroshima UHyogo UKyoto U
Kyushu UKyushu Tokai U
NIFSNiigata U
Tsukuba UU Tokyo
JAEAHebrew UIoffe Inst
RRC Kurchatov InstTRINITI
NFRIKAIST
POSTECHSeoul National U
ASIPPENEA, Frascati
CEA, CadaracheIPP, Jülich
IPP, GarchingASCR, Czech Rep
Columbia UCompXGeneral AtomicsFIUINLJohns Hopkins ULANLLLNLLodestarMITNova PhotonicsNew York UORNLPPPLPrinceton UPurdue USNLThink Tank, Inc.UC DavisUC IrvineUCLAUCSDU ColoradoU IllinoisU MarylandU RochesterU Tennessee U WashingtonU Wisconsin
NSTX-UNSTX-U Supported by
The First A3 Foresight Workshop on Spherical Torus (ST)
Jan. 14-16, 2013
SNU, Seoul, Korea
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U 2
Talk Outline• NSTX-U Mission
• NSTX Experimental Overview
• NSTX-U Construction Status
• NSTX-U Experimental Plan
• Summary
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Develop plasma-material-interface (PMI) solutions for next-steps– Exploit high divertor heat flux from lower-A/smaller major radius
• Fusion Nuclear Science/Component Test Facility (FNSF/CTF)– Exploit high neutron wall loading for material and component development– Utilize modular configuration of ST for improved accessibility, maintenance
• Extend toroidal confinement physics predictive capability– Access strong shaping, high , vfast / vAlfvén, and rotation, to test physics
models for ITER and next-steps (see NSTX, MAST, other ST presentations)
• Long-term: reduced-mass/waste low-A superconducting Demo
NSTX-U Mission ElementsFusion applications of low-A spherical tokamak (ST)
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Confinement scaling (electron transport)• Non-inductive ramp-up and sustainment• Divertor solutions for mitigating high heat flux• Radiation-tolerant magnets (for Cu TF STs)
•* Includes 4MW of high-harmonic fast-wave (HHFW) heating power
VECTOR (A=2.3)
JUST (A=1.8)
ARIES-ST (A=1.6)
Low-A Power Plants
Key issues to resolve for next-step STs
Parameter NSTX NSTX Upgrade
Fusion Nuclear Science Facility Pilot Plant
Major Radius R0 [m] 0.86 0.94 1.3 1.6 – 2.2
Aspect Ratio R0 / a 1.3 1.5 1.5 1.7
Plasma Current [MA] 1 2 4 – 10 11 – 18
Toroidal Field [T] 0.5 1 2 – 3 2.4 – 3
Auxiliary Power [MW] ≤ 8 ≤ 19* 22 – 45 50 – 85
P/R [MW/m] 10 20 30 – 60 70 – 90
P/S [MW/m2] 0.2 0.4 0.6 – 1.2 0.7 – 0.9
Fusion Gain Q 1 – 2 2 – 10
NSTX Upgrade will access next factor of two increase in performance to bridge gaps to next-step STs
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
TF OD = 40cm
Previous center-stack
TF OD = 20cm
RTAN [cm]__________________
50, 60, 70, 130 60, 70,120,13070,110,120,130
IP=0.95MA, H98y2=1.2, N=5, T = 10%
BT = 1T, PNBI = 10MW, PRF = 4MW
2x higher CD efficiency from larger tangency radius RTAN
100% non-inductive CD with q(r) profile controllable by:tangency radius, density, position
New 2nd NBIPresent NBI
Normalized e-collisionality e* ne / Te2
ITER-like scaling
ST-FNSF
?
constant q, ,
NSTX Upgrade
2x higher BT and IP increases T, reduces * toward ST-FNSF to better understand confinement
Provides 5x longer pulses for profile equilibration, NBI ramp-up
Newcenter-stack
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J. Menard, et al., Nucl. Fusion 52 (2012) 083015
NSTX Upgrade will address critical plasma confinement and sustainment questions by exploiting 2 new capabilities
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
TF flex-bus
CS Casing
TF cooling lines
TF Coil
OH Coil
PF Coil 1a
PF Coil 1b
PF Coil 1c
CHI bus
A schematic of the new center-stack and the TF joint area
New TF-Flex-Bus Designed and Tested to Full Cycles
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
The NSTX-U Inner TF Bundle Manufacturing Stages
New Zn-Cl-Free Soldering Technique Developed
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
NSTX-U Support Structural Upgrades
4x Electromagnetic Forces
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
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Relocation of the 2nd NBI beam line box from the TFTR test cell into the NSTX-U Test Cell.
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
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2nd NBI alignment performed and confirmed
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U •11
Beam-line Component Refurbishment
Ion Dump Calorimeter upgrade Bending Magnet
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
JK cap tack welded to the vacuum vessel after completing alignments, and full welding is now
underway (Jan. 3, 2013)
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
40” Torus Isolation (Gate) Valve received
TVPS valves, hardware, TMPs,
and shields
TVPS valves, hardware, TMPs,
and shields
Spool section & supportsCircular bellows
Exit spool piece
Rectangular bellows
NBI Duct and Torus Vacuum Pumping System (TVPS) components being procured
and fabricated
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
PF 1C
PF 1CCHI Gap
CHI Gap
CHI Gap
In-boardDivertor
Out-boardDivertor
HHFWAntenna
Center Stack
Primary Passive Plates
Secondary Passive Plates
NBI Armor
NSTX In-Vessel View and CHI Gap Protection Enhancement
Expect x 10 Higher Heat Load Into the CHI Gap
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• New CS provides higher TF (improves stability), 3-5s needed for J(r) equilibration• More tangential injection provides 3-4x higher CD at low IP:
– 2x higher absorption (4080%) at low IP = 0.4MA– 1.5-2x higher current drive efficiency
Present NBIMore tangential
2nd NBI
TSC simulation of non-inductive ramp-up from IP = 0.1MA, Te=0.5keV target at BT=1T
Non-inductive ramp-up from ~0.4MA to ~1MA projected to be possible with new centerstack (CS) + more tangential 2nd NBI
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
NSTX-U CHI Start-up ConfigurationsX 2 Higher CHI Driven Currents Expected
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
NSTXPlasma
Low-lossCorrugatedWaveguide
SteerableMirror
Launcher
NSTX Vacuum Vessel
28 GHz – 1MW Gyrotron by U. of Tsukuba
A schematic of the NSTX-U ECH/EBW launcher
NSTX-U ECH/EBW System for Non-Inductive Start-Up and Sustainment
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Disruption probability reduced by a factor of 3 on controlled experiments
– Reached 2 times computed n = 1 no-wall limit of N/li = 6.7
• Lower probability of unstable RWMs at high N/li
N
li
BetaN vs.li - Gridlines
0
1
2
3
4
5
6
7
8
0.0 0.2 0.4 0.6 0.8li
beta
N
N/li 13 12 11 10n = 1 no-wall beta limit line
0
1
2
3
4
5
6
7
8
0.0 0.2 0.4 0.6 0.8li
beta
N
14
N/li = 6.7
BetaN vs.li - XP948
0
1
2
3
4
5
6
7
8
0.0 0.2 0.4 0.6 0.8li
beta
N
n = 1 no-wall limit
ST-CTFST-Pilot
RWM State Space Control
n =
1 R
FA (
G/G
)
N/li5 10 15
1.5
1.0
0.5
0.0
Mode stability directly measured in experiments using MHD spectroscopy
Stability decreases up to N/li = 10
Stability increases at higher N/li Presently analysis indicates consistency
with kinetic resonance stabilization
Resonant Field Amplification (RFA) vs. N/li
unstablemode
J. Berkery IAEA
Unstable RWMStable / controlled RWM
S.A. Sabbagh
Stability control improvements significantly reduce unstable RWMs at low li and high N; improved stability at high N/li
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Disruption warning algorithm shows high probability of success
– Based on combinations of single threshold based tests
Results ~ 98% disruptions flagged with at
least 10ms warning, ~ 6% false positives
False positive count dominated by near-disruptive events
Disruptivity
Physics results Low disruptivity at relatively high N ~ 6;
N /Nno-wall(n=1) ~ 1.3-1.5
• Consistent with specific disruption control experiments, RFA analysis
Strong disruptivity increase for q* < 2.5 Strong disruptivity increase for very low
rotation
Warning Algorithms
S. Gerhardt IAEA
All discharges since 2006
N
liq*
Disruptivity studies and warning analysis of NSTX database are being conducted for disruption avoidance in NSTX-U
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Maintained stable “snowflake” configuration for 100-600 ms with three PF coils
• Maintained H-mode confinement with core carbon reduction by 50 %
• NSTX-U control coils will enable improved and up-down symmetric snowflake configurations
• Higher flux expansion (increased div wetted area)• Higher divertor volume (increased div. losses)
V. Soukhanovskii, NF 2009
NSTX “Snowflake” Divertor Configuration resulted in significant divertor heat flux reduction and impurity screening
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NSTX-U snowflake simula
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
With Lithium
Without Lithium
Lithium Improved H-mode Performance in NSTX
Te Broadens, E Increases, PH Reduces, ELMs Stabilize
Pre-discharge lithium evaporation (mg)
Te broadening with lithium
E improves with lithium
R. Maingi, PRL (2011)
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E improves with lower collisionality
S. Kaye, IAEA (2012)
No lithium (129239); 260mg lithium (129245)
H. W. Kugel, PoP 2008
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
• Li core concentration remained very low ≤ 0.05%. C remains dominant impurity even after massive (hundreds of milligrams) Li evaporation
• No apparent increase in Li nor C core concentration even at higher LLD surface temperature.
Li core concentration stays well below 0.1% for LLD temperature range of 90°C to 290°C
M. Podesta, IAEA (2012)
R=135-140 cm, t=500-600 ms
LiquidSolid
Reason for low lithium core dilution?:
• Li is readily ionized ~ 6 eV
• Li is low recycling – sticks to wall
• Li has high neoclassical diffusivity
F. Scotti, APS (2012)
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
•a)
•b)
•c)
•d)
• 2 identical shots (No ELMs)
– Ip = 0.8 MA, Pnbi ~ 4 MW
– high δ, fexp ~ 20
• 2, pre-discharge lithium depositions
– 150 mg: 141255
– 300 mg: 138240
• Tsurf at the outer strike point stays below 400° C for 300 mg of Li
– Peaks around 800° C for 150 mg
• Results in a heat flux that never peaks above 3 MW/m2 with heavy lithium evaporation
•Lithiated graphite
T. Gray. IAEA 2012
Clear reduction in NSTX divertor surface temperature and heat flux with increased lithium evaporation
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
Radiative Liquid Lithium Divertor Proposed Based largely on the NSTX Liquid Lithium Divertor Research
Flowing LL Particle Pumping Surfaces
Li+
Li++
Li+++
Li0
Heat Exchanger
B0
Divertor Heat and Particles Flux
Liquid Lithium (LL)
~ 1 l/sec
LL Purification System to remove tritium, impurities, and dust
Li Evap. /
Ionization
Li Radiative Mantle
Li wall coating /condensationLi path
Reduced Divertor Heat and Particle
Flux
Particle pumping by Li
coated wall
Divertor Strike Point
M. Ono. IAEA 2012
First Wall / Blanket
At 500°C – 700°C
000000000000000000000000
Core Reacting
Plasma
Edge Plasma
Scrape Off Layer
Flowing LLD Tray
200 – 450 °C
Closed RLLD
LL Out LL InLL In
RLLD
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
Design studies focusing on thin, capillary-restrained liquid metal layers
– Combined flow-reservoir system in “soaker hose” concept
– Building from high-heat flux cooling schemes developed for solid PFCs
– Optimizing for size and coolant type (Helium vs. supercritical-CO2)
Laboratory work establishing basic technical needs for PFC R&D
– Construction ongoing of LL loop at PPPL
– Tests of LI flow in PFC concepts in the next year
– Coolant loop for integrated testing proposed
PPPL Liquid Metal R&D for Future PFCsFor NSTX-U and Future Fusion Facilities
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M. Jaworski et al., PPPL
Valves
Impurities
EM Pumps
Liquid Lithium Divertor Tray
(LLDT)
200°C – 400°C
Divertor Heat and Particle Flux
Lithium Radiative
Mantle
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
Draft NSTX-U Research Plan Being Formulated
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A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U
Draft NSTX-U Research Facility Plan Being Formulated
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2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
1.5 2 MA, 1s 5s
NCC coils
0.2-0.4 MA plasma gun
0.3-0.5 MA CHI
0.5-1 MA CHINew
center-stack
2nd NBI
Upgrade Outage Advanced PFCs, 5s 10-20s
up to 1 MA plasma gun
U or LMo divertor
U + LMo divertor
Extend NBI duration or implement 2-4 MW off-axis EBW H&CD
1MW 2 MWECH/EBW
Divertor cryo-pump
UpwardLiTER
Flowing Li divertor or
limiter module
Li granule injector
All High-Z PFCs
Full toroidal flowing Li divertor
HHFW straps for EHO, *AE
Hot High-Z FW PFCs
NCC SPA upgrade
Enhanced RFA/RWM sensors
DBS, PCI or other intermediate-kHigh k
Bpolarimetry
Divertor Thomson
Dedicated EHO or *AE antenna
HHFW feedthru & limiter upgrade
U.S. FNSF conceptual
design including
aspect ratio and divertor optimization
Rotation control
qmin control
Snowflakecontrol
Control integration
Diagnostics for high-Z wall studies
MGI disruption mitigation
tests
Start-up and
ramp-up
Boundary physics
Materials and PFCs
Lithium
MHD
Transport & turbulence
Waves and Energetic Particles
Scenarios and control
A3 Foresight Workshop on ST Jan. 14- 15, 2013NSTX-UNSTX-U 28
Summary• NSTX-U Aims to Develop Physics Understanding Needed for Designing
Fusion Energy Development Facilities (ST-FNSF, ITER, DEMO, etc.)
• Develop key toroidal plasma physics understanding to be tested in unexplored, hotter ST plasmas
• Upgrade Project has made good progress in overcoming key design challenges
– Project on schedule and budget, ~45-50% complete
– Aiming for project completion in summer 2014
• Detailed NSTX-U Research Plan is being developed