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FPA Meeting, 10/11-12/05 Status of World ST Research
Status of World Spherical Torus ResearchMartin Peng
NSTX Program DirectorORNL@PPPL
Fusion Power Associates Annual Meeting and Symposium:Fusion and Energy Policy
October 11-12, 2005, Washington, DC
Supported by Office ofScience
College W&MColorado Sch MinesColumbia UComp-XGeneral AtomicsINELJohns Hopkins ULANLLLNLLodestarMITNova PhotonicsNew York UOld Dominion UORNLPPPLPSIPrinceton USNLThink Tank, Inc.UC DavisUC IrvineUCLAUCSDU ColoradoU MarylandU RochesterU WashingtonU Wisconsin
Culham Sci CtrU St. Andrews
York UChubu UFukui U
Hiroshima UHyogo UKyoto U
Kyushu UKyushu Tokai U
NIFSNiigata UU Tokyo
JAERIHebrew UIoffe Inst
RRC Kurchatov InstTRINITI
KBSIKAIST
ENEA, FrascatiCEA, Cadarache
IPP, JülichIPP, Garching
ASCR, Czech RepU Quebec
FPA Meeting, 10/11-12/05 Status of World ST Research
World Spherical Torus Research Is Expanding – 22 “Concept Exploration” and “Proof of Principle” Experiments
FPA Meeting, 10/11-12/05 Status of World ST Research
World Spherical Torus Research Is Addressing Important Issues in Fusion
• Active collaboration• “Concept Exploration” STs• “Proof of Principle” STs• Contributions in world fusion programs
FPA Meeting, 10/11-12/05 Status of World ST Research
World Spherical Torus Research Has a Tradition of Strong Collaboration
• Active bilateral exchanges– UK-US on NSTX and MAST – START collaboration in 1997– Japan-US on STs – active exchanges since 2000;
contributed to formation of All-Japan ST Program in 2004– RF-US on NSTX and Globus-M – since 1997– Brazil-US on initiation of ETE – collaboration since 2000
• Annual International ST Workshop since 1994; IAEA TM on ST since 1999
• Special international journal issues on progress of ST research– IEEJ jounral issue to appear in November– NF issue under preparation
• Progressing toward more coordination in research
FPA Meeting, 10/11-12/05 Status of World ST Research
CDX-U Have Carried out Liquid Lithium Tray Limiter Experiments
• Argon glow discharge cleaning and tray heating removed surface coatings
• Lithium remains in tray with currents to ground ≈100A at Bp≈0.1T for ≈10ms
Liquid lithium in tray after ~40 discharges. Liquid lithium
in tray limiter
• 34 cm major radius, 10 cm wide, 0.64 cm deep
• Two halves with toroidal break• Heaters for Tmax ≈500oC
FPA Meeting, 10/11-12/05 Status of World ST Research
Impurity Control with Liquid Lithium Indicated by Reduction of Oxygen Emission
Plasma Current (kA)
OII
Em
issi
on (
arb.
uni
ts)
With Lithium
No Lithium
Many conditioning shots required without Li to achieve currents ≈ 60kA
No conditioning shots required with Li to achieve currents > 60kA
FPA Meeting, 10/11-12/05 Status of World ST Research
Pegasus Is an Innovative ST to Explore Plasma Limits as A → 1
Pegasus (US)
FPA Meeting, 10/11-12/05 Status of World ST Research
Pegasus Is Exploring Innovative Startup via Electron Beam Injection
FPA Meeting, 10/11-12/05 Status of World ST Research
10
0
1
R (m)
a (m)
NSTX/MAST
LATE
QUESTAdvanced Fusion Research Center
TST-2 / TS-3/4“QUEST”
QUEST : Q-shu University Experiment on Steady State Spherical Tokamak
FPA Meeting, 10/11-12/05 Status of World ST Research
1 0-3
1 0-2
1 0-1
10 0
10 1
1 0-2 10 -1 1 00 10 1 1 02 103 10 4 1 05
BDFH
Ip(M
A)
T im e(s)
L A T E
T S T -2T R A IM -1M
N S T X
Research Region of QUEST
Time (s)
LATE
TST-2
NSTX / MAST
Proposed Device
Proposed Device
- 7 -
TST-2(Japan)
LATE(Japan)
FPA Meeting, 10/11-12/05 Status of World ST Research
Higher β,Higher fBS,
More compact
Longer pulse,steady state
CS-less op.
RF current drive
Comm. reactor
Very high β& steady state
NSTXMAST
UTST
QUEST
TS-3/TS-4
HIST, TST-2. LATE
Develop broader options for economical fusion reactor
Phase IIITarget
Strategy of the All-Japan ST Research Program(Prof. Yuichi Takase, June 2005)
Broad research utilizing all resources(existing ST, new ST at Kyushu, diagnostics,theory/modelling, reactor design, etc.)
FPA Meeting, 10/11-12/05 Status of World ST Research
Direct Measurement ofElectron Turbulence
Tangential scattering UCD
New Capabilities in NSTX
EF/RWM coils to extend β limits
Columbia
Novel j(r) diagnostics for Advanced physics
New PF1A coil for advanced shaping
FPA Meeting, 10/11-12/05 Status of World ST Research
0.9 1.0 1.1 1.2 1.3Major radius (m)
0.0
0.5
1.0
1.5
2.0
Tem
pera
ture
(keV
)
0
100
200
300
Toro
idal
vel
ocity
(km
/s)
Te
Ti
Vφ
#12546
0.9 1.0 1.1 1.2 1.3Major radius (m)
0.0
0.5
1.0
1.5
2.0
Tem
pera
ture
(keV
)
0
100
200
300
Toro
idal
vel
ocity
(km
/s)
Te
Ti
Vφ
#13035
L-mode H-mode
Ip ~750 kABT ~0.6T<ne> ~3x1019m-3
Ip ~750 kABT ~0.6T<ne> ~3x1019m-3
Spectrometer coupled to 224 chords64 toroidal chords on each NBI32 passive toroidal chords 64 poloidal chords (32 32 on/off-beam)
being commissioned
Enhanced CXRS (ΔR~ρLi) in MAST
FPA Meeting, 10/11-12/05 Status of World ST Research
χe ~ χi around mid-radius & close to χiZ-CH [Chang & Hinton]
H-mode Transport Coefficients Can Be Close to Ion Neoclassical
TRANSP modelling
Ti
Te
x1019
m-3
ne
FPA Meeting, 10/11-12/05 Status of World ST Research
STs Are Studying Super-Alfvénic Ion Heating for ITER and CTF
• NSTX has Super-Alfvénic ions (NBI), as in ITER (fusion α’s)
• Measured instabilities driven by such fast ions & coincidental fast ion losses
• Interactions driven by small ρfast* (ITER), copious fast ions (both), and Doppler shifted resonance with Alfvén instabilities (both)
• Will fusion α’s in ITER & CTF suffer similar losses?
0
1
2
3
4
5
6
/V Alfv始
0.0 0.2 0.4 0.6
CTF
ARIES-ST
NSTXITER
Supe
r-A
lfvén
ic
Central Fast Ion Pressure Fraction
Nor
mal
ized
Fas
t Ion
Spe
ed
Alfvén Mode Frequencies (kHz)
Energetic Neutral Particle Signal
NSTX 117541
Time (s)
Energy (keV)
Ln(fl
ux/E
0.5 )
(1/s
ter c
m2
eV1.
5s)
[E Fredrickson, S Medley]
FPA Meeting, 10/11-12/05 Status of World ST Research
Start-up Schemes – Double-Null Merging
compatible with future ST design
Double-null merging (DNM) involves breakdown at a quadrupole nullbetween pairs of poloidal coils in upper and lower divertor
Modelling predicts merging of plasma rings as current in coils ramped to zero
t=60ms Ip = 600 kA
t=15ms Ip = 150 kA t=21ms Ip = 250 kA t=45ms Ip = 450 kA
t=75ms Ip = 600 kA
FPA Meeting, 10/11-12/05 Status of World ST Research
After some optimisation, plasma current up to 340kA formed and plasma sustained for 0.3sec with zero current in central solenoid
Te ~ 0.5keV and ne ~ 9x1019m-3
Double-Null Merging Formation Demonstrated
FPA Meeting, 10/11-12/05 Status of World ST Research
NSTX Produced Sustained ST Plasmas via Coaxial HelicityInjection (Introduced by HIT-II)
Univ. of Hiroshima camera: N. Nishino; R. Kaita
6.2ms
8.0
9.8
11.6
12.4
13.3
15.1
16.9
• Rapid turn-off of injector current → closure of plasma surface → 60 kA, ~2 m2 volume
• First demonstrated on HIT-II (U Wash)• Important progress for attractive ST and
Tokamak fusion systems
Injector
ClosedPlasmaSurface
Plasma Current (kA/10)
Injector Current (kA)
Injector Voltage (kV*10)
FPA Meeting, 10/11-12/05 Status of World ST Research
ELM Spatial Structure (Experiment + Theory)
Image simulation of the expected structure with q95=4 and n=10
Filaments are consistent with the structures expected from the theory of the non-linear evolution of ballooning modes [Wilson and Cowley]
FPA Meeting, 10/11-12/05 Status of World ST Research
Unique ST Properties and Approaches Advance Boundary Physics
Turbulence imaging: large ρislow dynamics enable good
resolution
ITER-relevant heat fluxes (10 MW/m2).
Shaping & flux expansion
0
2
4
6
8
10
12
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1
Heat Flux [MW/m 2]
Radius [m]
InboardDivertorTarget
OutboardDivertorTarget
CHI Gap
4.9 MW
4.1 MW
#109063: 4.9 NBI#109053: 4.1 MW#109034: 2.0 MW (all H-mode)
2 MW
Heat, particle fluxes: Detached regimes, lithium coatings & liquid targets
ELITE (GA)ORNL, DIII-D
Pedestal stability: strong shaping, low A: magnetic geometry pedestal
stability & SOL transport
Dα
H97L
NSTX
FPA Meeting, 10/11-12/05 Status of World ST Research
NSTX Accesses High β, High Bootstrap Plasmas
CTF
NSTX⇒ Toroidal Physics (ITER)
⇒ Component Test Facility (CTF)⇒ Power Plant
Fusion RequiresHigh Beta
Steady State
CTF
FPA Meeting, 10/11-12/05 Status of World ST Research
• Improved divertor coils• Extended plasma to stronger shapes• High triangularity at high elongation leads
to quiescent core and edge conditions
Substantially Expanded the Spherical Torus Operating Space to Clarify Future ST Options
Tria
ngul
arity
Vertical Elongation
StrongerShapes
Energy Replacement Times
Nor
mal
ized
Per
form
ance
(βNH
89P)
2002-2003
20052004
[D Gates]
[J Menard]Demo
CTF
FPA Meeting, 10/11-12/05 Status of World ST Research
On-axis, counter-PINI
Jackable on/off-axis co-PINI
Double box: 2× co-PINIson- and off-axis
Investigating bold options for NBI current profile control
Flexible system 4 PINIs, up to 10 MW (1 counter- and 3 co-current)
Off-axis NBCD optimised with 2 off-axis co- and 2 on-axis co/counter PINIs
MAST Upgrades: Proposed NBI Systems
FPA Meeting, 10/11-12/05 Status of World ST Research
BUTTRESSES ⇒ Reduce Risk/Acceleration(Sir. Chris Llewellyn Smith, FPA meeting 2005)
Multi-beam material test facility - study damage from irradiation with heavy ions to material samples with implanted Helium ( + hydrogen?) Satellite tokamak - to be operated in parallel with ITER, as part of ITER programme, to test new modes of operation, plasma technologies,...Component Test Facility (CTF) - to test engineering structures (joints, …) in neutron fluences typical of fusion power stations
We assume that a ‘fast track CTF’ (possibly a small spherical tokamak that would not need to breed tritium?) could be operating with D-T in 2026
Assuming successful development, it would speed up the advent of fusion power significantly and reduce risks (note that in ‘Pillars only’ model DEMO phase 1 is effectively a very expensive and large CTF)
FPA Meeting, 10/11-12/05 Status of World ST Research
ST Research Contributes to Major Components of Office of Science 20-Year Strategic Plan for Fusion
ComponentTest Facility
PerformanceExtension Test
ITER PerformanceEnhancement
FPA Meeting, 10/11-12/05 Status of World ST Research
World Spherical Torus Research Is Expanding and Addressing Important Issues in Fusion
• Growing in breadth and depth – 22 experiments in active collaboration
• “Concept Exploration” STs push the ST scientific envelope– Explore high leverage innovations– Establish basis for “Proof of Principle” testing
• “Proof of Principle” STs– Contribute to resolve issues important to ITER burning
plasma performance– Establish scientific feasibility for ST “performance
extension,” CTF volume neutron source, & Demo Optimization
• STs are part of plans in world fusion programs