National Spherical Torus Experiment Facility / Diagnostic Overview Supported by Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics NYU ORNL PPPL PSI SNL UC Davis UC Irvine UCLA UCSD U Maryland U New Mexico U Rochester U Washington U Wisconsin Culham Sci Ctr Hiroshima U HIST Kyushu Tokai U Niigata U Tsukuba U U Tokyo JAERI Ioffe Inst TRINITI KBSI KAIST ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching U Quebec Masayuki Ono For the NSTX Team 46 th Annual Meeting of Division of Plasma Physics, American Physical Society November 15 - 19, 2004 Savannah, Georgia
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National Spherical Torus Experiment Facility / Diagnostic Overview Supported by Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar.
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National Spherical Torus Experiment
Facility / Diagnostic Overview
Supported by
Columbia UComp-X
General AtomicsINEL
Johns Hopkins ULANLLLNL
LodestarMIT
Nova PhotonicsNYU
ORNLPPPL
PSISNL
UC DavisUC Irvine
UCLAUCSD
U MarylandU New Mexico
U RochesterU Washington
U WisconsinCulham Sci Ctr
Hiroshima UHIST
Kyushu Tokai UNiigata U
Tsukuba UU Tokyo
JAERIIoffe Inst
TRINITIKBSI
KAISTENEA, Frascati
CEA, CadaracheIPP, Jülich
IPP, GarchingU Quebec
Masayuki OnoFor the NSTX Team
46th Annual Meeting of Division of Plasma Physics, American Physical Society
November 15 - 19, 2004Savannah, Georgia
Designed to Study High-TemperatureToroidal Plasmas at Low Aspect-Ratio
Achieved ParametersAspect ratio A 1.27Elongation 2.6Triangularity 0.8Major radius R0 0.85m
Plasma Current Ip 1.5MA
Toroidal Field BT0 0.6T
Solenoid flux 0.7VsAuxiliary heating & current drive:
NBI (100kV) 7 MWRF (30MHz) 6 MWCHI 0.4MA
Pulse Length 1.1sStored Energy 400 kJT ~ 40%
• Ip flattop ~ 3.5skin
• W flattop ~ 10 E
• T>20%, N>5, E/E,L>1.5 for ~10 E
• IBS/Ip = 0.5, IBeam/Ip = 0.1
Operational and Physics Advances Have Led to Significant Progress Towards Goal of High-T, Non-Inductive
Operation
fBS = IBS/Ip = 0.5 1/2 pol
T = <p>/(BT02/20)
H-mode plasma
Research Topics to Achieve Long-Pulse, High Performance Plasmas Are Identified
• Enhanced shaping improves ballooning stability
• Mode, rotation and error field control allows high beta
• NBI and bootstrap sustain most of current
• HHFW heating contributes to bootstrap
• EBW provides off-axis current & stabilizes tearing modes
• Particle and wall control maintains proper density
• Successfully operated for 21.1 weeks with 2460 plasmas– Met the Joule milestone of 18 weeks and programmatic goal of 20 weeks
• Significantly expanded plasma operational regimes toward the NSTX longer term goals:– High ~ 2.5 plasma controlled by faster plasma control system– Simultaneous high T - high j-bootstrap regimes expanded– Effective plasma pulse duration (pulse Ip/ITF) doubled
• Meeting all the FY 04 research milestones:– High beta plasma (T ≥ 25%) sustained for longer than 2 E
– MSE-CIF now yielding core current profile information– Core and edge fluctuations measured and characterized– EBW emission measurement suggests good coupling efficiency– New solenoid-free start-up experiments conducted with “transient” CHI
and with outer PF coils
NSTX had a very productive FY 04 Run
– Gradual joint resistance increase observed in many stressed joints at 4.5 kG
– Further joint monitoring revealed greater than anticipated flag movements
– For machine safety, TF limited to 3 kG during the last month of operation
– Out-of-spec flag movement traced to not-fully-penetrated epoxy fill
– Through R&D, a reliable full-penetration epoxy-fill technique developed
– Other improvements implemented– Appropriate design reviews are
being conducted
TF-Joints issues being resolved
NSTX plasma operations to resume in Feb. 2005
MHD
Tools to reach near ideal MHD limits
Improved Plasma Control System Opened Operating Window During 2004
Campaign
Reduced latency improved vertical control at high-, high-T
Capability for higher allowed higher IP/aBT
Significantly more high-T
(N=6.8 %mT/MA achieved)
More routine high Longer current flattop duration pulse = (>0.85 Ip,max)
Time of peak T
New PF 1A Coils to improve plasma shaping
114465
PF1A
Achieved2004
Goal of2005• Shorter PF 1A is needed to
improve the plasma shaping control ( = 2.5 and = 0.8) for advanced ST operations.
• Due to the success of high operation this year, the new PF 1A coil will be installed this year ahead of schedule.
• Should be available for FY 05 run starting in Feb. 05.
Active Control Will Enable Study of Wall Mode Interactions with Error Fields & Rotation at High T
Columbia U, GA, PPPL
Res
istiv
e W
all M
ode
Gro
wth
Rat
e (s
-1)
Internal Sensors
Conducting Plates
Vacuum Vessel
Ex-Vessel Feedback Control Coil System Status
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
• A pair of the Ex-Vessel Feedback Control Coils installed and energized with the preprogrammed power supply in July, 2004.
Full Ex-Vessel Feedback Control Coil System is scheduled to be available for the FY 05 experimental run.
Transport and Confinement
Measuring Fluctuations to gain understanding of plasma transport
Pfusion ~ H5-7
Measured magnetic field pitch in a ST for the first time
MSE-CIF j(r) diagnostic
MSE Multistage Lyot Filter• Calibrated in situ and achieved the desired statistical errors of 0.2°/0.4° at 4.5/3.0 kG• Initial 8 ch data were collected with 4 ch activated at one time.• MSE data being incorporated into EFIT and other codes.
time(sec)
MSE-CIF measured q(0) and Raxis
• q(0) ~ 0.8 before ~1 after crash• Raxis shift inboard ~ 2 cm after crash• 5 msec resolution
Nova Photonic Inc
8 ch will be available for the FY 05 run and increased to 12 - 14 ch.
Correlation length measurements
Reflectometry Turbulence Measurements
UCLA Reflectometer
• Array of microwave reflectometer horns
• Aligned perpendicular to magnetic flux surfaces
Fast X-ray Camera Reveals Core Electron Dynamics
t=0 t=90s t=180s t=270s
Images with time resolution down to ~ 2 µs
CCD camera
Image intensifierinside magnetic shield
Pinholes andBe foils
PSIImage of core n=1 tearing mode
High k scattering measurements will be developed in FY’ 05
• Initial system will allow range of k measurements in select locations (2 - 20 cm-1)
• Access to ETG possible!
• Major installation this opening.
High k scattering
Luhmann (UC Davis), Munsat (U. Colorado) Mazzucato, Park, Smith (Princeton U.)
UCD
Non-Inductive SustainmentHHFW Off-axis Heating and CD
EBW CD for profile control*
Multiple Roles of HHFW
• Bulk plasma heating to enhance bootstrap currents in advanced ST Operations
• Plasma start-up and current ramp-up
• Super-Alfvénic energetic particle physics (UCI)
- HHFW modification of NBI fast ion distribution function
- TAE mode stablization
• Edge physics for RF- Anomalous edge ion heating- Phase dependent heating
efficiency- Parametric instabilities
&
12 antennas powered by 6 MW sources
ORNL, UCI, MIT, GA, CompX
EBWs Can Generate Critical Off-Axis Current Drive in NSTX at High
NSTX, = 40%
00 1r/a
Charles Kessel (PPPL) Tokamak Simulation Code
Comp-X
• ~ 100 kA of off-axis CD neededto sustain ~ 40% in NSTX
• Cannot use ECCD in NSTX since pe/ce ~ 3-10
• Modeling indicates that EBWCD can provide needed current
• EBWCD may also assist startupand stabilize NTM's
• 4 MW, 28 GHz EBWCD system planned for NSTX
Strong Diffusion Near Trapped-Passing BoundaryEnables Efficient Ohkawa Current Drive
CompX GENRAY/CQL3D
NSTX, T = 42%
1 MW “Proof-of-Principal” EBW System Tests Viability of Heating & Current Drive in NSTX
1 MW
• ~ 750 kW EBW power delivered to plasma--> Use EBWCD to locally
drive 30-40 kA
• If 1 MW system is successful increase RF power to 4 MW with addition of three more gyrotrons, transmission lines & launchers by
--> Provide 3 MW of EBW power in the plasma & Generate > 100 kA
(CPI or Gycom)
Power and Particle Handling
NSTX has largest “P/R” in tokamaks/STs comparable to ITER
viewing area≈ 25x25 cm
spatial resolution≈ 1-2 cm
Gas Puff Imaging Diagnostic
RF limiter
separatrix
Using Princeton Scientific Instruments PSI-5 camera 250,000 frames/sec @ 64 x 64 pixels/frame300 frames/shot, 14 bit digitizer, intensified
Typical image
PSI, Nova Photonics
Fast probe provided edge density and temperarure profile
ne rises faster than Te
UCSD
Outer divertor not detached yetLLNL
Lithium Pellets Injection to Control Particle Recycling