no li 130374 130386 130388 130389 no li 47 mg 5 mg/s 10 mg/s
TRANSCRIPT
No Li
130374130386130388130389
No Li47 mg5 mg/s10 mg/s
• All eleven shots technically successful – small timing problem
• Ramp-ups and square wave temporal profiles employed
• Rates from 1 mg/s to ~ 35 mg/s employed
• NSTX much more tolerant of Li powder than expected
• Total of 82 mg injected during 11 shots
• Not a great day for NSTX reproducibility or documentation
• 3 - 5 shots have some scientific merit
• Observed significant decrease in D and ELMs
• Timing and location of deposition appeared to be important
XP-828 Initial Results and Observations
Extra Slides
Prototype Acoustic Resonance Dropper Can Drop from 0.3 mg up to Much-Too-Much Powder (Li Surrogate)
Velocity at SOL = 4.5 m/sec
Powder Injector
to Vac Pump
1.0 m
2 ¾ Gate Valve
Laser Scattering Module
Drop Chamber
Bracing½ O.D. StainlessTubing
Pyrex Tube 2 ½ O.D.
Glass Funnelw Long Stem
to Vac Pump
Existing Computerized Laboratory Test Facility
New Umbrella Throttle Seems to Work More Reliably Than Old Simple Throttle Design – Higher Fluxes
Simple Throttle Umbrella Throttle
HigherReliableParticle Flow
Li Powder
Li Powder
(~ 3 mg/s)
0 2 4 6 8 10 12 14 160
2
4
8
10
12
14
6
RMS Voltage (Volts)
Mas
s F
lux
(mg/
s)
Lithium Particle Flux is an Approximately Linear Functionof Resonant Voltage Applied to the Piezoelectric Membrane
0 1 2 3 4 5 6 7
Sca
tter
ed L
aser
Sig
nal (
A.U
.)
Time (s)
0.5 V: 0.4 mg/s
1.0 V: 0.7 mg/s
2.0 V: 1.5 mg/s
3.0 V: 2.2 mg/s
8.0 V: 5.8 mg/s
Laser Scattered Signal Reproducibility is Fairly Good However, Signal Saturates at 2 - 4 mg/s (3 - 5 Vrms)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
0.02
0.04
0.06
0.08
0.091
0.01
NewVolts
6.9
NewVolts2
6.9
NewScat 0.003
NewScat2
10 Time0.2 0.4 0.6 0.8 1.00
Time (s)
RM
S V
olta
ge (
Vol
ts)
0
2
4
8
6
Scattered Laser S
ignal (A.U
.)
Two Arbitrary Waveforms: Ramp-Ups (4 & 8 Volts Max)Laser Scattered Signal Saturates at 2 - 4 mg/s (3 - 5 Vrms)
6 mg/s
3mg/s
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0
0.02
0.04
0.06
0.08
0.091
0.01
NewVolts
6.9
NewScat 0.000
10 Time0.2 0.4 0.6 0.8 1.00
Time (s)
RM
S V
olta
ge (
Vol
ts)
0
2
4
8
6
Scattered Laser S
ignal (A.U
.)
6 mg/s
Arbitrary Waveform: Ramp-Down (8 Volts Max) Same Laser Scattering Saturation Observed
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
RM
S V
olta
ge (
Vol
ts)
0
4
8
12
Time (s)
Scattered Laser S
ignal (A.U
.)
6 mg/s
An Arbitary Waveform: With Some Modifications Might “Tweek” ELMS
“Early” Li Can be Preferentially Directed to Lower Divertor
Pre-Pulse of Lithium for50 ms (~ 100 Oscillations)850 ms Before Breakdown
Small Plasma Initiatedon the Center StackFlux Plot Shown Just After Breakdown
The Two Plasmas to be Used in XP 828
129019 129059
XP828 Shot No.
Droppermg/s (Max)
TemporalProfile
Total Lithium
(mg)HeGDC (min)
Ref #1 0 N/A 0 6
Ref #2 0 N/A 0 6
Ref #3 0 N/A 0 6
1 3 A 2 6
2 6 A 6 6
3 12 A 12 6
4 12 or TBD A 24 6
5 12 or TBD B 36 6
6 12 or TBD B 48 6
7 12 or TBD B 60 6
8 12 or TBD B 72 6
9 12 or TBD C 84 6
10 12 or TBD C 96 6
11 12 or TBD C 108 6
12 8 TBD 116 6
13 10 TBD 126 6
14 12 TBD 138 6
15 14 TBD 152 6
------- ------- -------- ------- -------
Pla
sma
Cur
rent
Time (sec)
Li F
lux
0 1
Pre-programmed Flux Profile Must be Injected ~ 450 ms Before Plasma Breakdown
450 ms
0 1 2 3 4 5 6 7 80
0.01
0.02
0.03
0.04
0.05
0.06
0
NewDiff
1.05 Fit X_v( )
80 Volt X_v
0 2 4 6 8 10 12 14 160
2
4
8
10
12
14
6
BT = 0.5 T
Ip = 800 kA
PRINCETON PLASMA PHYSICS LABORATORY
PPPL
Purpose : Study ELM Suppression by in situ Modification of NSTX Plasma Surface Interaction: Li on Graphite
R/a = 1.46
Lower Single Null
PNBI = 4 MW
Type 1 ELMS
Lithium Evaporators with Shutters
H. Kugel P2-58
B treated Graphite
2
Velocity at SOL = 4.5 m/sec
Powder Injector
Dropper byAcoustic Resonance
VerticalInjection by AcousticResonance
HorizontalInjection byPZT Fan
100 m
Resonating Piezoelectric Disk
SLMP Li Powder
ResonantLevitation
ResonantDropping
= ± 0.5 mm~ 5 lbs
0,1 Mode 290 Hz
0,2 Mode 2 kHz
0,3 Mode
Modes of the Vibrating Piezoelectric Drumhead
0,2 Mode of Piezoelectric Disk with Glass Beads – 2 KHz
0,2 Node of Piezoelectric Disk with Glass Beads – 2 KHz
30 mil
Scale 20:1
Throttle: ¼ - 28 Screw
Piezoelectric Membrane
(0,2) Node
3.5 mg/s0.3 mg/s
100 - 300 mg/s
g
Fixed LevelInside Node
N.B. 30mil Gap:15 particles high20 particles wide
O-Ring
100 mil
ResonantDropping
Resonating Piezoelectric Disk
ResonantLevitation
25 mm
(0,2) Mode
Dusting ofGlass SpheresLevitated from Center of Mode
Throttle used to force Particles to drop throughHole in piezo membrane
Dropper byAcoustic Resonance
VerticalInjection by AcousticResonance
HorizontalInjection byPZT Fan
(or by RotatingWheel)