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

BACKUP

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

Observed Plasma Rotation Damping Agrees with Theory