1 / 13

Profile Comparisons from the MAST/NSTX Power Threshold Identity Experiment

Research Supported by. Profile Comparisons from the MAST/NSTX Power Threshold Identity Experiment. Rajesh Maingi Oak Ridge National Laboratory Hendrik Meyer UKAEA Fusion And the NSTX and MAST Teams NSTX Physics Meeting March 8, 2004 Princeton, NJ.

dolf
Download Presentation

Profile Comparisons from the MAST/NSTX Power Threshold Identity Experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Research Supported by Profile Comparisons from the MAST/NSTX Power Threshold Identity Experiment Rajesh Maingi Oak Ridge National Laboratory Hendrik Meyer UKAEA Fusion And the NSTX and MAST Teams NSTX Physics Meeting March 8, 2004 Princeton, NJ Page 1

  2. NSTX and MAST save similar plasma size but MAST vacuum vessel larger and outer walls further away Vpl/VVV ~ 35-40% NSTX Vpl/VVV ~ 6-10% MAST Passive stabilizing plates Page 2

  3. First Detailed MAST/NSTX Identity Experiment Has Been (Nearly) Completed! Goals: • compare L-H power threshold in same CDND (double-null with drsep < 3mm) shape with same Ip, Bt, density, inner-wall midplane fueling location, etc. • determine if PLH lowest with drsep=0 (go to +/- 10 mm) Results: • CDND NBI power very similar near LH transition (~300-350 kW); need to compute PLOSS • LDND (DN with drsep ~ 10 mm, downward) had higher PLH > 1.7 MW • NSTX shape was a little bigger, and was developed with rtEFIT control (needs only a little more development) Page 3

  4. Dithery H-mode in CDND near PLH in MAST 0.5 0.0 1.0 0.0 0.4 0.0 0.0 Ip [MA] ---- 8842 ---- 8851 ---- 8848 ---- 8852 PNBI [MW] PLH ne [1019 m-3] Type III ELMs Da[au] dithers 0.0 0.1 Time[s] 0.2 0.3 Page 4

  5. NSTX dithers not as ‘periodic’ as MAST (CDND near PLH) “firm” L-H “dithers” Page 5

  6. NSTX #111378 277msec (NBI 700 kW) MAST #8851 200msec (NBI 580 kW) NSTX #111378 343msec MAST #8851 300msec Z (m) Z (m) R (m) R (m) CDND Shapes were reasonably well matched, although NSTX shape (under rtEFIT) was a little larger Double-null Drsep<1mm (“CDND”) NSTX vac. ves. Double-null Drsep<1mm (“CDND”) NSTX vac. ves. Page 6

  7. NSTX ne profile more peaked and Te profile broader early R [m] R [m] R [m] yN yN yN Page 7

  8. NSTX ne (Te) lower(higher) later in H-mode phase R [m] R [m] R [m] yN yN yN Page 8

  9. Clear H-mode Transition in LDND near PLH in MAST 0.4 0.0 2.0 0.0 0.6 0.0 0.0 ne [1019 m-3] PLH PNBI [MW] Ip [MA] ---- 8856 ---- 8857 ---- 8859 Da[au] L-H (ELM-free) L-H (ELMy) 0.0 0.1 Time[s] 0.2 0.3 0.4 Page 9

  10. No transition observed in LDND in NSTX (too low density or MHD at NBI turn-on?) (Reconstructed) (no H-mode) Sawteeth Page 10

  11. NSTX #111383 391msec (NBI 1.1 MW) MAST #8859 280 msec (NBI 1.4 MW) NSTX #111381 301msec NSTX #111380 301msec Z(m) Z(m) R(m) R(m) NSTX LDND shape a little larger than MASTMagnetic balance (drsep) scan possible with rtEFIT Single-null Drsep~10mm (“LDND”) NSTX vac. ves. Single-null Drsep~+/- 3mm (“LDND”,”UDND”) NSTX vac. ves. Page 11

  12. NSTX never achieved H-mode in LDND, but maybe needed a little more power or higher density? R [m] R [m] R [m] yN yN yN Page 12

  13. Summary and Future Work • First joint NSTX/MAST experiment was a good first step toward the proposed 3-way NSTX/MAST/DIII-D collaboration on the effect of aspect ratio on pedestal • CDND power threshold was remarkably similar in terms of NBI power -> wall proximity does not play a big role in these conditions?! • Higher power CDND discharge had type IIII ELMs in MAST but largely ELM-free in NSTX • Need more LDND data from NSTX (w/edge rotation data…) • Need to work out issues related to mapping of profiles inside and outside of magnetic axis • Need better comparison shots well in H-mode, at higher Ip… Page 13

More Related