XP on SOL profiles, scaling with density and power

1. XP on SOL profiles, scaling with density and power J. Boedo H. Kugel, D. Rudakov, A. Pigarov, N. Crocker,R. Maingi, M. Umansky, B. Kaita, S. Paul, S. Zweben, R. Maqueda, D. D’Ippolitto, J. Myra, NSTX Team J. Boedo NSTX

2. Previous Xps • OP-XP-217 Characterization of the Boundary Layer and • Power Flow to the Divertor, S.F. Paul, J. Boedo, R. Maingi • Probe had mechanical failure, no data. • Power and density scan • OP-XP-437 Characterization of turbulence in the NSTX boundary, J. Boedo, K. C. Lee, H. Kugel, S. Zweben, R. Maingi • Mostly dedicated • Best existing data 112812-112844. Some discharge development • Position scan for K. C. Lee • No H-mode shots • Continuation Jul 13th, 113818, 3kG, no good shots • Need to fill ne gaps and do power scan and H-mode. J. Boedo NSTX

3. Original Probe Proposal (2001) • High resolution profiles • Scalings • Turbulence • Intermittency • L-H Transition physics • Radial electric Field • Fluctuation changes • GAMs • Zonal Flows • Reynolds Stress • Originally combined with Divertor power scan • Then combined with turbulence J. Boedo NSTX

4. L-Mode discharges ~1.6 MW, Ne scan J. Boedo NSTX

5. L-mode Te, ne, Profiles Obtained Profiles with high (~2 mm) spatial resolution 3 ms time resolution Upgrading to 2 ms resolution in 04/05 Data well inside the LCFS Plasma exists far into the SOL An offset is needed for proper fits >> fast radial transport J. Boedo NSTX

6. L-mode Vf, Er Profiles Obtained Radial field increases quickly to ~5.5 kV/m Poloidal tips well aligned No dedicated H-mode data, mining database J. Boedo NSTX

7. Ne profile wider than Te. Ne, Te quite flat in SOL Te rise is faster than Ne rise Calibration or EFIT ~2 cm off J. Boedo NSTX

8. Scaling in lTe, lne, can be obtained Trend of Ne and Te decay length with ne averaged are opposite, but they converge at high ne_av What happens at low Ne? Need more data and fill gaps! J. Boedo NSTX

9. Scaling in Te1, ne1 obtained Te1 shows a marked dependence on average density Ne1 does not! J. Boedo NSTX

10. Te0, Ne0, fairly constant (except at low Ne?) Need to examine low Ne behavior More statistics needed Scaling information useful to modelers (blob modeling, UEDGE, BOUT) J. Boedo NSTX

11. Electric field moves outward at high density Clear “transition” at ~3.0E13 cm-3 So far (nominal 5 cm inside), no well. Need to make further experiments and go further in. ? J. Boedo NSTX

12. Density Fluctuation Levels Decrease at LCFS The shear layer/LCFS (marked by double lines) and seen in the floating (not plasma) potential, shifts out at high density Normalized density fluctuation levels (Nrms/N) shift accordingly Normalized fluctuation levels vary from ~ 0.2 in the shear layer to ~0.7-0.8 at the LCFS dropping to ~0.5-0.6 in the SOL J. Boedo NSTX

13. Intermittency Conditional averaging results reveals that Intermittency strong in NSTX Amplitude of blobs decreases with radius Fast Te measurement will resolve Te in the blobs J. Boedo NSTX

14. ELMs Resolved by Probes Type I ELM over 6 ms Type V ELM over 6 ms J. Boedo NSTX

15. Conclusions Te profile narrower than Ne profile. Fast Te rise at R-Rsep~-5 cm Te profile completely flat at 15 eV in the SOL Ne profile also flattish in the SOL, but less so than the Te profile Pedestal temperature profile quite sensitive to discharge density, density profile fairly insensitive (mostly decay length) Intermittency is strong in NSTX. Blobs decay quickly with radius Density fluctuation levels are low (0.2) in the pedestal and increase at the LCFS (~0.7) to decrease slightly (0.5) into the SOL Floating potential sensitive to density. Shifts out at high Ne. J. Boedo NSTX