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Reciprocating Probe Edge/SOL Profiles in NSTX

Reciprocating Probe Edge/SOL Profiles in NSTX. J. Boedo H. Kugel, D. Rudakov, H. Ji, T. Carter, N. Crocker, D. Rudakov, M. Umansky, D. Gray, A. Pigarov, D. D’Ippolitto, J. Myra, R. Maingi, V. Soukhanovskii, Ricardo Maqueda (Nova Photonics), S. Zweben and the NSTX Team

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Reciprocating Probe Edge/SOL Profiles in NSTX

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  1. Reciprocating Probe Edge/SOL Profiles in NSTX J. Boedo H. Kugel, D. Rudakov, H. Ji, T. Carter, N. Crocker, D. Rudakov, M. Umansky, D. Gray, A. Pigarov, D. D’Ippolitto, J. Myra, R. Maingi, V. Soukhanovskii, Ricardo Maqueda (Nova Photonics), S. Zweben and the NSTX Team CO3 ORAL session, Monday afternoon, November 15 J. Boedo APS 04

  2. L-mode, 0.8 MW, LSN plasmas with density scan Plunges 0 0.1 0.2 0.3 0.4 Discharge fueling rate and probe insertion time varied to sample various densities J. Boedo APS 04

  3. L-mode Te, ne, Profiles Obtained with high spatial resolution Profiles with high (~2 mm) spatial resolution 3 ms time resolution Data inside the LCFS Plasma exists far into the SOL Te is quite flat!! An offset is needed for proper fits >> fast radial transport J. Boedo APS 04

  4. Fixed Power, Density Scan.Scaling in lTe, lne, can be obtained lTe usually smaller than lne Trends of lTe, lne with ne_av are opposite lTe, lne converge at high both high and low ne_av (physics behind this?) J. Boedo APS 04

  5. Fixed Power, Density Scan. Amplitude, Te1, shows a marked dependence on average density Ne1 does not! Te Profile shifts out with density J. Boedo APS 04

  6. Fixed Power, Density Scan. Offset Te0, Ne0, fairly constant (except at low Ne?) SOL ballistic transport not too sensitive to ne_av? Need to examine low Ne behavior with more statistics J. Boedo APS 04

  7. L-mode vs H-mode SOL, LSN, 2 MW Ne SOL decay length: 3-4 cm in H-mode Ne SOL decay length: 10-30 cm in L-mode Te SOL decay length: >50 cm in BOTH L and H mode. SOL radial particle transport larger in L-mode SOL heat transport ALWAYS large J. Boedo APS 04

  8. SOL Transport Probably Dominated by Intermittency in NSTX Conditional averaging results reveals that Intermittency strong in NSTX in BOTH L and H-mode Amplitude of Intermittent Plasma Objects decreases with radius in L and H mode Future fast Te measurement will resolve Te in the IPOs to separate particle and heat flux R-Rsep~ 1.6 cm R-Rsep~ 10 cm J. Boedo APS 04

  9. L-H Mode Profile Difference Lies on the Number of IPOs R-Rsep~ 1.6 cm R-Rsep~ 10 cm Although IPO amplitude somewhat higher in L mode, in NSTX the EVENT FREQUENCY is the chief difference between L and H mode J. Boedo APS 04

  10. Conclusions Te profile: 1) Narrower than Ne profile, 2) rises faster except at extreme ne, 3) most sensitive to <ne>, 4) quite flat at ~10-15 eV in the SOL >> SOL heat transport is fast! Ne profile: 1) Also flattish in the SOL, 2) sensitive to <ne> mostly via lne L-H comparison: SOL lne length is much larger in L-mode, SOL lTe, ALWAYS large >> SOL particle transport faster in L mode,SOL heat transport ALWAYS fast! Intermittency is strong in NSTX. IPOs decay quickly with radius, drained by parallel transport Main difference on the intermittency between L and H mode NSTX is the frequency of the IPOs and not their amplitude J. Boedo APS 04

  11. 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 APS 04

  12. 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 APS 04

  13. 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 APS 04

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