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)