Flows Turbulence and the Edge Plasma in NSTX

Flows, Turbulence, and the Edge Plasma in NSTX C. E. Bush, S. Zweben, R. Maqueda, W. Davis, D. Johnson, R. Kaita, H. Kugel, L. Roquemore, G. Wurden and the NSTX Team • XP 442 - Scoping Study of Ohmic H-modes • Fast Cameras - Flows, turbulence, and phenomena • Tile Langmuir Probes NSTX 2004 Results Review, Sept. 20 -21

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 Page 2 ELMFree OH ELMy C. Bush, Results/Forum 2004 OH

Goals • • • Page 3 Scoping study in parameter/configuration space Measure turbulence in core and edge of Hmode simultaneously Assess use as Target Plasma C. Bush, Results/Forum 2004

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 k. A, 3. 0 to 4. 5 k. G TF – Short H-mode at Ip = 600 k. A, Bt = 3 k. G OH H-modes obtained for 1 st 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 Page 4 C. Bush, Results/Forum 2004

PLOSS for NBI and OH Hmodes Page 5 C. Bush, Results/Forum 2004

Edge measurements (ERD) in Ohmic H-modes show Er and Vp change prior to L-H transition Shot 113350 1. 0 0. 8 0. 4 Ip (MA) H-mode Er and Vp begin to change 10 to 20 ms before L-H transition (here at t ~ 0. 220 sec) 0. 0 -0. 5 -1. 0 -1. 5 Er (k. V/m) -2. 0 -2. 5 5 0 -5 VT (km/s) -10 -15 5 0 -5 -10 -15 Vp (km/s) 0. 16 0. 24 0. 20 0. 28 Time (s) Page 6 C. Bush, Results/Forum 2004

Highest Normalized b (b. N ~ 35%) Shot: Perturbed by an External Kink Mode: (CIII filter) Shot 114463 Page 7 C. Bush, Results/Forum 2004

H-mode Showing Quiescent External Kink Small Torus at EOS: (CIII filter) Shot 114151 Page 8 C. Bush, Results/Forum 2004

Medium ELM Images #2 #113484 @ 4 µsec/frame (Da light) Page 9 C. Bush, Results/Forum 2004

Activity Near Inner Wall During and Following an ELM (157 -175 ms) Shot 113862 Magnetic field line plot from EFIT Page 10 C. Bush, Results/Forum 2004

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 • Tile Langmuir • Some Isat, Te, ne data in Tree soon Probes Page 11 C. Bush, Results/Forum 2004

Future Plans • • • Page 12 Continue XP 442 – Get core turbulence data – Finish scoping studies Fast camera studies – Add filters – CI, Li. II, Neon – Correct fisheye distortion Langmuir Probes – Get data in tree – Additional probes (? ) C. Bush, Results/Forum 2004

Backup Slides Extras

Ion Saturation Current vs. Time Isat 0. 12 Raw isat data 0. 08 0. 04 0. 00 Isat 0. 08 0. 10 0. 20 Time [s] 0. 30 0. 40 112830, Smoothed over 2 sweeps 0. 04 0. 00 Page 14 0. 10 0. 20 Time [s] C. Bush, Results/Forum 2004

Activity Near Inner Wall During an ELM (160 ms) Shot 113862 From EFIT Page 15 C. Bush, Results/Forum 2004