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ELMs / LLD

The Two Types of Discharges in XP-913. Standard Fiducial. ELMs / LLD. Comparison: LITER, Aerosol and No Lithium Shots No Li 700 mg LITER 7 mg Early Li Aerosol. b N. NeL. CII. I P. W MHD. P RAD. t MHD. P NBI. MHD. I OH. D a. Int. Induct.

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ELMs / LLD

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  1. The Two Types of Discharges in XP-913 Standard Fiducial ELMs / LLD

  2. Comparison: LITER, Aerosol and No Lithium Shots No Li 700 mg LITER7 mg Early Li Aerosol bN NeL CII IP WMHD PRAD tMHD PNBI MHD IOH Da Int. Induct.

  3. Six Interesting Features from XP-828 • The (apparent) extreme efficacy of Li aerosol at increasing confinement • The extremely “square” Te and ne profiles seen during the NBI overdriven L-H transition • The reduced OH consumption during aerosol injection • The transient suppression of ELMs • The concomitant reduction in radiated power / Zeff • The lack of CS gas fuelling

  4. 129012 130388 LFS CS 130389 Standard Fiducial Baseline XP-913 Baseline XP-913 No CS Gas

  5. Standard Fiducial Baseline XP-913 129012 130388 LFS CS Li Flux Baseline XP-913 (No CS Gas) 130389 Flux Profile A Li Flux

  6. LFS LFS CS CS Li Flux Flux Profile B Flux Profile C Li Flux

  7. Shot 121522: A Discharge Used to Deposit Li on the CS for the Benefit of the Following Discharge 30 ms 250 ms 500 ms 600 ms

  8. Li Li Another Tactic for Directing Li Ions - In This Case to the Lower Divertor Example: Shot 128279

  9. Extra Slides

  10. Comparison: Zeff(0) from Metals No Li 700 mg LITER7mg Early Li Aerosol Estimated Contribution of Metals to Zeff 0.6 LITER 0.4 Dimensionless 0.2 Aerosol Injection No Li 0 0 0.2 0.4 0.6 0.8 Time (sec) S. Paul

  11. Goal(s) of the XP • Establish whether or not the 1st aerosol experiment was a fluke. • Fiducials: H mode by early NBI overdrive - no CS gas • Early aerosol injection – before L-to-H transition • 10 mg/s and higher – probe the limit of Li aerosol mass flux • Push plasma performance • If problems try OH shot or two • -------------------------- If time permits ------------------------------------ • 2. Investigate effects on ELMs. • Can aerosol trigger small ELMs at higher flux rates (>35mg/s)? • 3. Investigate whether more Li atoms can be injected than D2 atoms. • LLD loading - need relevant discharge • 4. Investigate Li efficacy with double null discharges

  12. Shot 130388: Early Injection of Li Powder • Nominal aerosol trajectories shown by red vertical lines Plasma Encounters Aerosol Particles X-Point Established (H-mode @ 180 ms) Stored Energy Steady State Li+1Rings Observed (Fig 12) 25 ms 58 ms 80 ms 102 ms 509 ms

  13. 2005 First LSN NBI D Shot After 25 mg of Li Pellet Injection Exhibited Factor ~50% Decrease in Density Lower single-null divertor discharges, 0.45T, D2 gas fueling 3.5mg • 25 mg of Li pumping of edge density saturated after the 3 similar D discharges and returned to pre-Li wall conditions, as expected if most injected gas reacts with the deposited Li. • Rate of density rise is below NBI fueling rate. H. Kugel M. Bell

  14. Camera View of Early Li Aerosol InjectionTaken at t ~ 60 ms

  15. The Subtle Difference Between 130386 and 130389 130386 @ 85 ms No Li 130389 @85 ms Early Powder

  16. Why a Double Null Discharge Would be Interesting Powder Injector Li Ions Head Preferentially for Upper Strike Points

  17. Getting Toward the Center Stack ( or LLD) - Early (Using a “Splash Plate”) ~ 45 Deg Inverted Spoon ~ 45 Deg Flat Plate Present Design Flat Plate LLD

  18. Aerosol Injection 10 mg/s

  19. Aerosol Injection 10 mg/s

  20. Early Powder Injection

  21. Early Li 2 sec shot

  22. Li Has Unique Energy Structure – Easy to Create Li+1 Can We Exploit This to Save Early Volt Secs ? +1 Ionization Energy (eV) +2 +3

  23. Shot 121522 30 ms 250 ms 500 ms 600 ms

  24. Shot 123862 30 ms 250 ms 500 ms 800 ms

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