flows, turbulence, and the edge plasma in nstx c.e. bush, s. zweben, r. maqueda, w. davis, d....
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Flows, Turbulence, and the Edge Plasma in NSTXC.E. Bush, S. Zweben, R. Maqueda, W. Davis, D. Johnson, R. Kaita,
H. Kugel, L. Roquemore, G. Wurden and the NSTX Team
NSTX 2004 Results Review, Sept. 20-21
• XP442 - Scoping Study of Ohmic H-modes• Fast Cameras - Flows, turbulence, and phenomena• Tile Langmuir Probes
C.Bush, Results/Forum 2004
Page 2
Motivation
• Ohmic H-modes have low centrally peaked densities– Explore edge and core turbulence simultaneously– Target plasma for early NBI and combined ITB and ETB
NBI OHELM-Free
OHELMy
C.Bush, Results/Forum 2004
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Goals
• Scoping study in parameter/configuration space
• Measure turbulence in core and edge of H-mode simultaneously
• Assess use as Target Plasma
C.Bush, Results/Forum 2004
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Results for Ohmic H-mode Scoping Study
• One-half run day – mini-scans in Bt and Ip
– Some OH-H-modes randomly on other days
• H-modes at 600 to 900 kA, 3.0 to 4.5 kG TF
– Short H-mode at Ip = 600 kA, Bt = 3 kG
• OH H-modes obtained for 1st time ever on NSTX during this run
– Most readily obtained after hot boronization
– Alternating helium conditioning shots seem to help
– Obtained both double null (DN) and lower single null (LSN) divertor
– Most short duration, some with ELMs and some ELM-free
• Peaked Central ne
– ELMy: Small high frequency ELMs (?) keep ears from developing
– ELM-free: have ears, but edge peak lower than central ne
• No turbulence measurements made in core of OH H-mode
• Some edge reflectometer fluctuation data; Some GPI data, not L-H
C.Bush, Results/Forum 2004
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PLOSS for NBI and OH Hmodes
C.Bush, Results/Forum 2004
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Edge measurements (ERD) in Ohmic H-modes show Er and Vp change prior to L-H transition
Er and Vp begin to
change 10 to 20
ms before L-H
transition (here at
t ~ 0.220 sec)
H-mode
Shot 113350
Time (s)
Vp (km/s)
VT (km/s)
Er (kV/m)
Ip (MA)
0.16 0.20 0.24 0.28
1.00.8
0.4
0.0-0.5
-1.0
-10
5
0
-5
-1.5
-2.0
-2.5
-1550
-10
-15
-5
C.Bush, Results/Forum 2004
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Highest Normalized Shot: Perturbed
by an External Kink Mode: (CIII filter) Shot 114463
C.Bush, Results/Forum 2004
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H-mode Showing Quiescent External Kink Small Torus at EOS: (CIII filter)
Shot 114151
C.Bush, Results/Forum 2004
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#113484 @ 4 µsec/frame (D light)
Medium ELM Images #2
C.Bush, Results/Forum 2004
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Activity Near Inner Wall During and Following an ELM (157-175 ms)
Shot 113862
Magnetic field lineplot from EFIT
C.Bush, Results/Forum 2004
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Langmuir Probes
• Flush mounted single probes
• Total of 22 probes, 6 top and 6
bottom divertors
– Remainder along centerstack
• Have data for vast majority of shots
• Virtually no signal from centerstack
probes when plasma is diverted
• Some Isat, Te, ne data in Tree soon• Tile Langmuir
Probes
C.Bush, Results/Forum 2004
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Future Plans
• Continue XP442– Get core turbulence data– Finish scoping studies
• Fast camera studies– Add filters – CI, LiII, Neon– Correct fisheye distortion
• Langmuir Probes– Get data in tree– Additional probes (?)
Backup Slides
Extras
C.Bush, Results/Forum 2004
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Ion Saturation Current vs. Time
0.12
0.08
0.04
0.000.00 0.10 0.20 0.30 0.40
0.08
0.04
0.00
0.00 0.10 0.20 0.30 0.40
112830, Smoothed over 2 sweeps
Raw isat data
I sa
tI s
at
Time [s]
Time [s]
C.Bush, Results/Forum 2004
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Activity Near Inner Wall During an ELM (160 ms)
Shot 113862
From EFIT