SMK – IAEA ‘04 1 Stanley M. Kaye for the NSTX Research Team PPPL, Princeton University, U.S.A. 20 th IAEA Fusion Energy Conference Vilamoura, Portugal November 2004 Progress Towards High Performance Plasmas in the National Spherical Torus Experiment (NSTX) 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
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Stanley M. Kaye for the NSTX Research Team PPPL, Princeton University, U.S.A.
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 - PowerPoint PPT Presentation
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SMK – IAEA ‘04 1
Stanley M. Kayefor the NSTX Research TeamPPPL, Princeton University, U.S.A.
20th IAEA Fusion Energy ConferenceVilamoura, Portugal
November 2004
Progress Towards High Performance Plasmas in the National Spherical Torus
Experiment (NSTX)
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
SMK – IAEA ‘04 2
NSTX Is Designed To Study Toroidal Confinement Physics at Low Aspect Ratio and High T
Aspect ratio A 1.27
Elongation 2.5
Triangularity 0.8
Major radius R0 0.85m
Plasma Current Ip 1.5MA
Toroidal Field BT0 0.6T
Pulse Length 1s
Auxiliary heating:
NBI (100kV) 7 MW
RF (30MHz) 6 MW
Central temperature1 – 3 keV
Aspect ratio A 1.27
Elongation 2.5
Triangularity 0.8
Major radius R0 0.85m
Plasma Current Ip 1.5MA
Toroidal Field BT0 0.6T
Pulse Length 1s
Auxiliary heating:
NBI (100kV) 7 MW
RF (30MHz) 6 MW
Central temperature1 – 3 keV
Establish physics database for future Spherical Torus (ST) devices
Non-solenoidal current generation/sustainment key element of program
SMK – IAEA ‘04 3
• 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
SMK – IAEA ‘04 4
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)
SMK – IAEA ‘04 5
T Can Be Limited by Internal Modes – Rotation Dynamics Important
• Flow shear/diamagnetic effects slow internal mode growth• Coupled 2/1, 1/1 modes eventually reduce rotation T collapse
Menard EX/P2-26
SMK – IAEA ‘04 6
Resistive Wall Modes Can Limit T at Low q
Newly installed active coils for error field/RWM control will provide means to stabilize external modes
Sabbagh EX/3-2
10% above no-wall limit for manywall times (wall ~ 5 msec)
n=1-3 components measured bynew internal magnetic sensors
- first observation of n>1
NSTX exhibits a broad spectrum of instabilities driven by fast ion resonance
Fredrickson EX 5-3
N
(G)
(G)
(G)
Bp(n=1)(deg
)B
z(G
)
n=1 no wall unstable
n=2,3
|Bp|(n=1)
|Bp|(n=2)
|Bp|(n=3)
(f<40 kHz, odd-n)
0.22 0.24 0.26 0.28t(s)
-20-10010200
100200300010
20300102030400204060
02
46
0.18 0.20 0.22 0.24 0.26 0.28t(s)
-20-10010200
1002003000
10
20010
20300102030
02
46
114147
FIG. 1
114452
Critical rotation frequency ~ 1/q2
SMK – IAEA ‘04 7
Systematic Scans Reveal Stored Energy Increases With Plasma Current in NBI Discharges
~ Linear dependence at fixed BT, Pinj
0
5
0.0 0.1 0.2 0.3 0.4 0.50
100
Time (s)
0
5
0
1
0.5 1.0 1.5Radius (m)
Ip [MA]
PNB [MW]
WMHD [kJ]
We [kJ]
100200
300
0
1
0
ne [1019m-3]
Te [keV]
ne [1019 m-3]
Te [keV]
SMK – IAEA ‘04 8
Parametric Dependences of NSTX Energy Confinement Time Established
Some tokamak trends reproduced in thermal and global E’s
• E exceeds tokamak scalings• L~H; L more transient• BT dependence observed
E,th/pby2 = 0.5 to 1.4
Global E from magnetics
SMK – IAEA ‘04 9
Long-Wavelength Turbulence Measured in Core for First Time in an ST Through Correlation Reflectometery
Core density fluctuations influenced strongly by magnetic fluctuations – radial correlation lengths long
Lc, ne/ne larger at lower BT
~0.45-0.7
Lc scales as s
SMK – IAEA ‘04 10
NSTX Has Investigated Regimes of ReducedElectron Transport
• Electron transport generally dominant (neo≤i<<e in H-mode)• Produced electron ITBs using fast current ramp, early NBI in low density (ne0~21019 m-3) L-modes
ETG modes predicted to be linearly stable in region of reversed shear(gyrokinetic calculations)
Stutman EX/P2-8
TRANSP magneticdiffusion
Reverse shear corroborated by observation of double-tearing modes
SMK – IAEA ‘04 11
NSTX Has Developed MSE for Current Profile Measurements at Low BT
• Preliminary reconstructions performed• Agreement with TRANSP modeling good