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NSTX Status and Plans NSTX Status and Plans
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 Rep
U.S.
International
presented by
R. J. Hawrylukfor
M. Ono and the NSTX Team
NSTX Just Completed 2006 Experimental Campaign Exploiting New Capabilities and
Regimes
• Non-axisymmetric feedback coils for error field and resistive wall mode control
– Plasma rotation physics
• Operated to 0.55T provided BT confinement scaling data
- E(Ip or Bt)1.5 at fixed q.
• High-k scattering for electron-scale fluctuation.
• Optimized shaping with new PF coils for high triangularity and elongation
S
• High triangularity reduced divertor heat flux and obtained small ELM regime.
• Lithium Evaporator reduced density and oxygen impurities.
• Successful non-inductive start-up by CHI
NSTX is Testing Active Mode Control System
• NSTX mode control system similar to US proposal for ITER– Located at vertical midplane
– Coils behind vessel wall
– Fields couple to nearby blanket-like passive conducting structure
– Excellent test-bed for validating ITER control models
• NSTX research:– Error field correction
– Plasma rotation reduction/control
– Active Resistive Wall Mode control
VALEN Model of NSTX
6 ex-vessel midplane control coils
SS VacuumVessel
Copper passiveconductor plates
internal
sensors Columbia University, GA
Plans - Using fast and improved feedback system, explore effectiveness of closed-loop EF / RWM control on the high performance long-pulse plasmas above the "no-wall" beta limit.
Resistive Wall Mode Stabilized at ITER-relevant Low Rotation
Plasmas
• Plasma rotation reduced by non-resonant n = 3 magnetic braking
• Clear demonstration of Resistive Wall Mode stabilization in low rotation plasmas.
t(s)0.4 0.5 0.6 0.7 0.8 0.9
0.40 0.50 0.60 0.70 0.80 0.90t(s)
0.00.51.01.52.0
05
10152005
1015200.00.51.0
1.5
02468
Shot 120047
0
2
4
6
N
IA (kA)
Bpun=1 (G)
/2 (kHz)
N > N (n=1)no-wall
120047
120712
< crit
92 x (1/RWM )
64208
40
1.51.00.50.020
100
Newly Installed High-k Scattering Diagnostic Probes Turbulence Related to
Electron Transport
4002000
-200-400
0.0 0.1 0.2 0.3 0.4 0.5 0.6Time (s)
4002000
-200-400
4002000
-200-400
4002000
-200-400
4002000
-200-400
kr=20cm-1
kr=16cm-1
kr=12cm-1
kr=8cm-1
kr=4cm-1
H-mode
10
8
6
4
2
0
Frequency (kHz)
Unprecedented spatial resolution at electron-scale at short wavelengths due to good access
Plans: Characterize local high-k turbulence and electron heat transport. Measure poloidal/toroidal rotation and determine radial electric field shear to constrain theory.
UC Davis
• ITER will operate in regime with many overlapping modes– Mode physics depends on Vb/VAlfvén.
– High fast(0) / tot(0) in NSTX provides drive for multiple modes
– NSTX can study multi-mode regime while measuring the internal magnetic field.
1% neutron rate decrease:5% neutron rate decrease:
Plans: Measure, identify & characterize instabilities driven by super-Alfvénic ions and associated fast ion transport.
UCI, UCLA, JAEA
NSTX Accesses ITER-relevant Energetic Particle Regime
Boundary Physics: Increased Triangularity Reduces
Peak Heat Flux to Divertor Target
Configurations
Single Null Double Null Double Null
0.4 0.4 0.8
Peak heat flux
1 0.5 0.2
ELM Type Type I Mixed Type V (small)
117407 LSN117432 DN117424 high- DN
0
2
4
6
8
10
12
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1Radius [m]
Tile Gap
6 MW DN ( L~0.40)
(MW DNL~.7)
( )outer strike region
#1177: .373LSN@ s#1173: .31DN@ s#117: .31DN@ s
(MW LSNL~.)
117407 LSN
117432 DN
117424 high- DN
ORNL, LLNL
6MW DN (L~0.40)
Plans: Effects of lithium wall coating on particle recycling and improved confinement. Divertor/edge at low plasma collisionality with ITER-level heat flux.
Progress in Non-Inductive Startup and Rampup
Plams: Ramp-up CHI initiated solenoid-free start-up plasmas to substantial plasma currents via heating and current drive by Neutral Beam Injection and High Harmonic Fast Wave. Long-pulse plasmas in conditions relevant to CTF and advanced operations in ITER.
Axisymmetric reconnection at the injector to result in formation of closed flux surfaces
Ip = 160 kA on closed flux
surfaces when Iinj = 0
Univ. of Washington
Highest Elongation and Plasma Shape Factor for Advanced
Operations • Machine improvements have increased steady state shaping factor
€
S ≡ q95 Ip aBt( ) MA /(m ⋅Tesla)[ ]
200520042002-3
= 2.75, = 0.8, S ~ 37 = 2.0, = 0.8, S ~ 23
= 2.3, = 0.6, S ~ 27 = 2.95, = 0.65, S ~ 40
2006
Record elongation