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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. Fig 1. 129012. 130388. 130389. XP 913 Section #1 Discharges. Standard Fiducial. Baseline XP-913. LFS.
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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. Fig 1
129012 130388 130389 XP 913 Section #1 Discharges Standard Fiducial Baseline XP-913 LFS CS LFS CS Baseline XP-913 No CS Gas LFS No CS gas puff (Replaced with LFS Li Aerosol) Fig 2
XP 913 Section #1 Discharges with Li Flux Profiles Standard Fiducial Baseline XP-913 129012 130388 LFS CS gas puff LFS CS gas puff 50 mg/s 10 mg/s Li Flux Baseline XP-913 (No CS Gas) 130389 LFS Flux Profile A Max Rate 1 (from above) Li Flux Fig 3
XP 913 Section #1 Discharges with Li Flux Profiles LFS No CS gas puff Flux Profile B 50 mg/s 40 mg/s 30 mg/s 10 mg/s Li Flux Flux Profile C LFS No CS gas puff 50 mg/s 40 mg/s 30 mg/s 50 mg/s 40 mg/s 30 mg/s 10 mg/s Li Flux Fig 4
Shot 118980: A Discharge Used to Deposit Li on the CS for the Benefit of the Following Discharge t = 50 ms 150 ms 300 ms 500 ms Fig 5
Shot 118980: A Discharge Used to Deposit Li on the CS for the Benefit of the Following Discharge Three shots to find Max Rate 2 50 mg/s 30 mg/s Profile D 10 mg/s Li Flux Fig 6
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
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
Li Li Another Tactic for Directing Li Ions - In This Case to the Lower Divertor Example: Shot 128279
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
The Subtle Difference Between 130386 and 130389 130386 @ 85 ms No Li 130389 @85 ms Early Powder
Why a Double Null Discharge Would be Interesting Powder Injector Li Ions Head Preferentially for Upper Strike Points
Aerosol Injection 10 mg/s
Aerosol Injection 10 mg/s
Early Powder Injection
Early Li 2 sec shot
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
Status of the Li Droppers Dropper #1: Tested and Installed on NSTX – pumping out before TIV opens (1 to 2 days) Dropper #2: Li powder degassed, vacuum housing baked out (10-8 Torr), dropper assembled but must be pumped down in the vacuum housing for 7 to 10 days without baking. Could be installed by 6/26/09 to 6/28/09 – depends on lab pump-out rate. Need to finish the XP-913 approval process
3.6 2.25 kHz 2.63 kHz 3.2 2.8 300 kHz 2.4 375 kHz 2.0 Glass Beads Flux (gm/s) 1.6 1.2 0.8 0.4 0 0 5 10 15 20 25 30 35 Applied RMS Voltage (V) Behavior of 50 mm Glass Beads in the Dropper vs Voltage and Frequency (resonance)
Li Powder Flux is Similar to Glass Bead Flux with Scaling Factor ~ 0.53 Freq : 90 Scaled Glass Bead Data 2.25 kHz (Resonant) 80 Li Powder Data 70 2.63 kHz ~ 2.5X106 /s = 80 TL/s (D2) 60 300 kHz 50 Li Flux (mg/s) 40 375 kHz 30 20 10 0 0 2 4 6 8 10 12 14 Applied RMS Voltage (V)
Preparing the Li Powder for Use in NSTX (Out-gassing Residual Solvent) 25 mg Li Powder: 109 particles, 7 m2 contained in a flat pan for max out-gassing To Turbo Pump for ~ 2 weeks