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SEWG MEETING, Cadarache, June 16th 2009 1/18 Experimental studies on laser induced removal and...
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Transcript of SEWG MEETING, Cadarache, June 16th 2009 1/18 Experimental studies on laser induced removal and...
SEWG MEETING, Cadarache, June 16th 2009 1/18
Experimental studies on laser induced removal and collection for absorbing particles
A.Vatry1,2, A. Marchand1, Ph. Delaporte1, C. Grisolia2, M. Sentis1,
C. Hernandez2, H. Roche2
1 Lasers, Plasmas and Photonic Processes Laboratory, Marseille, Francewww.lp3.univ-mrs.fr
2 Association Euratom/CEA, DRFC/SIPP, Saint Paul lez Durance, France
SEWG MEETING, Cadarache, June 16th 2009 2/18
MOTIVATIONS
The dust have high adhesion force the laser is a good solution for the removal
This is the first step for the cleaning
Decontamination of fuel tubes (AREVA, ONET, CEA) Microelectronics
Particles : Moxsubstrate : zircalloy
Optics
Particles : polymersubstrate : silicon
Particles : organic, metallicsubstrate : silica
Removal technique based on laser cleaning are developed in various field
Advantages : handle remote, free contact
SEWG MEETING, Cadarache, June 16th 2009 3/18
Experimental set-up
aperture
Attenuating plate lens
laser
Examples of optical microscope images of C particles on Si substrate:
N0 particles
Substrate with particles
dVacuum chamber
N particles
PRE set-up
Before the irradiation After 5 shots at 200mJ/cm²
aperture
Attenuating plate lens
Laser
Collector substrate
Collection set-up
Collector substrates have been observed with
an optical and scanning electron microscopes
4 ns – 1064 nm
0
1N
NPRE
SEWG MEETING, Cadarache, June 16th 2009 4/18
lens
XeCl laser
target
substrate
KrF
laser
▪ Dusts are produced by laser
ablation of graphite or W target and
are collected on substrate
The laser-produced dusts have
similar morphologies and nature
than Tokamak ones.
Tokamak and Argon discharge
Laser at LP3
200nm
Experimental set-upTextor
ASDEX Upgrade (PSI poster Balden)
DC Argon discharge
C produced under vacuum (10-2mbar)
W produced under air
C produced under air
Dusts production
sample
SEWG MEETING, Cadarache, June 16th 2009 5/18
Carbon particles produced by laser
200nm1µm
Produced under air:
Produced under low pressure:
C on Si produced under 10 mbar d’He
▪ Layer and particles
▪ sizes ~ < 1 µm
▪ Very porous
▪ Amorphous structure
900
800
700
600
500
400
300
1600140012001000800
Bande D
Bande GI (u.a)
Raman shift (cm-1)
Raman spectrum achieved in PIIM laboratory(Cédric Pardanau)
1µm
▪ Separated particles
▪ Various shapes
▪ sizes ~ < 1 µm
▪ Very porous
SEWG MEETING, Cadarache, June 16th 2009 6/18
PRE for carbon particles
4 ns – Si substrate
Wavelength influence:
▪ Laser is very efficient to remove carbon particles, for F> 500 mJ/cm² More than 80% of particles are removed
▪ Wavelength has a low influence on the PRE
▪ Pulse duration has low influence, except for a long pulse duration as 200 ns
Influence of laser parameters :
Pulse duration influence:
0
0,2
0,4
0,6
0,8
1
0 200 400 600 800 1000 1200Fluence (mJ/cm²)
PR
E f
or 5
sho
ts
450 fs
50 ps
7 ns
At 200 ns - 1064 nm PRE = 0 for fluences up to 1.16 J/cm²
1025 nm-1064 nm
SEWG MEETING, Cadarache, June 16th 2009 7/18
PRE for carbon particles
Si and SiO2 have very different thermal and optical properties
However the curves are quite similar
PRE and then removal mechanism do not depend on the substrate properties
0
0,2
0,4
0,6
0,8
1
0 100 200 300 400 500 600 700 800
Fluence (mJ/cm²)
PR
E f
or
5 s
ho
ts
C on Si
C on SiO2
50 ns – 308 nm
Substrate influence:
0,0
0,2
0,4
0,6
0,8
1,0
0 200 400 600 800 1000 1200
Fluence (mJ/cm²)
PR
E fo
r 5
shot
s
C on SiO2
C on Si
4 ns – 1064 nm
SEWG MEETING, Cadarache, June 16th 2009 8/18
Collection of carbon particles
Almost no intact particles are collected
The carbon particles are ablated during the irradiation
Collector substrate for d = 5 mm, under 10-3mbar, for 1 shot F = 380 mJ/cm²
The ejected carbon particles are in the form of very thin nanoparticles or/and atoms
KrF laser: 248 nm – 27 ns
Carbon particles produced by laser ablation
SEWG MEETING, Cadarache, June 16th 2009 9/18
Removal mechanism of carbon particles
▪ The removal mechanism is the particle ablation, due to the direct absorption of the laser energy by the particle▪ If the particle is too big, the removal is achieved in several steps
SEWG MEETING, Cadarache, June 16th 2009 10/18
Comparison with dust from Tore Supra
Carbon particles produced by laser ablation Dust collected in Tore Supra
Laser is also efficient for the particle collected in Tore SupraThe difference of efficiency is explained by the difference of size
4 ns – Si substrate 248 nm– 27 ns – Si substrate
SEWG MEETING, Cadarache, June 16th 2009 11/18
Carbon dust on CFC tile
248 nm - 27 ns - 300 mJ/cm²
Before irradiation 5 shots
Sample achievement:
Result:
A laser is focused on a CFC tile
Particles are deposited around the crater
We irradiate the tile with a laser at 300 mJ/cm²CFC tile
SEWG MEETING, Cadarache, June 16th 2009 12/18
▪ Particles produced by PLD with tungsten target 2 kinds of particles
► Very thin aggregates (foam)
► Droplets of 1 to 5 µm with very smooth surface
Tungsten particles produced by laser
W droplets are also produced in plasma device or by arcing in Tokamak
Produced by plasma gun
Collected in ASDEX Upgrade
Produced by laser
SEWG MEETING, Cadarache, June 16th 2009 13/18
1064 nm - 4 ns - ~700 mJ/cm²248 nm - 27 ns - ~800 mJ/cm²
▪ UV range is very efficient to remove the very thin aggregates
0 shot
1 shot
Removal efficiency for W thin aggregates
▪ Infrared range do not remove efficiently thin aggregates
SEWG MEETING, Cadarache, June 16th 2009 14/18
Laser could be efficient to remove tungsten particles but for specific parameters
Wavelength has a great influence on PRE
UV beam is more efficient than infrared one
PRE of W droplets
The pulse duration has an influence too
But the damage threshold of the substrate is very low we cannot use picosecond and femtosecond pulse duration for our application
4 ns – Si substrate
Wavelength influence:
Influence of laser parameters :
Pulse duration influence:
At 200 ns - 1064 nm PRE = 0 for fluence up to 1,25 J/cm²
SEWG MEETING, Cadarache, June 16th 2009 15/18
Collection of tungsten particles
Collection:
Collector substrate for d = 5 mm, under 2.10-2 mbar, 1 shot, F = 700 mJ/cm²
Collector substrate for d = 3 mm, under air, 5 shots, F = 700 mJ/cm²
A lot of intact particles have been collected under air and primary vacuum
KrF laser
248 nm – 27 ns
SEWG MEETING, Cadarache, June 16th 2009 16/18
1000
800
600
400
200
0
806040200
2000
1500
1000
500
Temperature (K)
Time (ns)
FORTRAN 1D simulation :
Temperature below the fusion threshold
Studies on tungsten particles removal
30 shots5 shots
4 ns – 1064 nm – ~700 mJ/cm²
No particle damage
Collection results are in accordance to FORTRAN simulation Particles could not be ablated
1000
800
600
400
200
0
806040200
2000
1500
1000
500
Depth (µm)
5 shots1 shots No particle damage
27 ns – 248 nm – ~800 mJ/cm²
1000
800
600
400
200
0
806040200
1200
1000
800
600
400
Depth (µm) Temperature (K)
Time (ns)
1000
800
600
400
200
0
100806040200
1200
1000
800
600
400
Particles not removed Particles not removed
Temperature below the fusion threshold
SEWG MEETING, Cadarache, June 16th 2009 17/18
248 nm - 27 ns - 500 mJ/cm²
Before irradiation 5 shots
5 µm
Tungsten dust on CFC tile
Sample achievement:
Result:
lens
XeCl laser
Tungsten target
KrF
laser
CFC tile
A laser is focused on a W target
Particles are deposited on the CFC tile
SEWG MEETING, Cadarache, June 16th 2009 18/18
Summary
The laser is efficient to remove dust
For tungsten dust specific parameters are required
The carbon dust are ablated collection of atom and/or very thin nanoparticles
The tungsten droplets are ejected intact collection of micrometer particles
SEWG MEETING, Cadarache, June 16th 2009 19/18
Thank you for your attention
SEWG MEETING, Cadarache, June 16th 2009 20/18
PRE for W droplet
Substrate influence:
0
0,1
0,2
0,3
0,4
0,5
0,6
0 500 1000 1500 2000
Fluence (mJ/cm²)
PR
E
W on Si
W on SiO2
50 ns – 308 nm
The substrate can has an influence
However, in both case, for absorbent and transparent substrate the laser can remove carbon particle
50 ps – 355 nm
SEWG MEETING, Cadarache, June 16th 2009 21/18
1000
800
600
400
200
0
806040200
8000
6000
4000
20001000
800
600
400
200
0
806040200
2000
1500
1000
500
Temperature (K)
Time (ns)
FORTRAN 1D simulation:
Temperature below the fusion threshold
Studies on tungsten particles removal
Temperature (K)
Time (ns)
Depth (µm)
Temperature above the fusion and vaporization threshold
Vaporization (5828 K)
Fusion (3695 K)
30 shots5 shots
4 ns – 1064 nm – ~700 mJ/cm²
No particle damage 5 shots
1 µm
Particle damage
Collection results are in accordance to FORTRAN simulation Particles could not be ablated
1000
800
600
400
200
0
806040200
2000
1500
1000
500
1000
800
600
400
200
0
100806040200
8000
6000
4000
2000
Depth (µm)
50 ps – 1064 nm – 540 mJ/cm²
Particles not removed Particles not removed
SEWG MEETING, Cadarache, June 16th 2009 22/18
Studies on tungsten particles removal
248 nm – 27 ns – 800 mJ/cm²
1025 nm – 450 fs – 300 mJ/cm²355nm – 50 ps − 290 mJ/cm²
5 shots4 shots
0 shot 1 shot
1 shot
Under the removed particle the substrate is not affected by the laser
SEM observations:
SEWG MEETING, Cadarache, June 16th 2009 23/18
Field modification around the W particles :
7 ns – 1064 nm – ~ 800 mJ/cm² 450 fs – 1025 ns – ~300 mJ/cm²355nm – 50 ps − 290 mJ/cm²
15 shots5 shots 15 shots
Simulation made by Nicolas Bonod (Fresnel Institute)
▪ The Si texturization allows the materialization
of the field around the particle
▪ The interface is in the particles shadow
▪ No interface mechanism could be at the origin
of the removal
Studies on tungsten particles removal
5µm
Possible removal mechanism :
▪ Particle ablation
▪ Explosive evaporation of humidity
▪ Thermally induced expansion
▪ Local substrate ablation
▪ Electrostatic force
SEWG MEETING, Cadarache, June 16th 2009 24/18
Studies on tungsten particles removal
First calculations about electrostatic force (266 nm- 4ns- 800 mJ/cm²):
Comparison between Van der Waals force and Electric force :
Force between positive charge of 5 µm particles and photo-electrons at 4ns :
F = ~ 2x10-7 N
The adhesion force between a metal particle (with
deformation) and the silicon subtrate is ~10-6 or 10-7 N
This is the same order of magnitude
Pulse duration influence :
For picosecond and femtosecond regime
multiphotonic effect
More photoelectrons
Higher removal efficiency
Pulse duration influence:
Si substrate
SEWG MEETING, Cadarache, June 16th 2009 25/18
Particle removal mechanism
Thermally induced expansion Local substrate ablation
Explosive evaporation
Destruction of substrateMechanical process
temporal parameters
Adsorbed humidity
Particle ablation
depends on materials
Electrostatic force
▪ Different physical
mechanisms could lead to
the particle removal
▪ Several mechanisms could
be involved simultaneously
in the removal
SEWG MEETING, Cadarache, June 16th 2009 26/18
0
0,2
0,4
0,6
0,8
1
0 200 400 600 800 1000 1200Fluence
PR
E
450 fs
50 ps
7 ns
Influence des paramètres laser (sur Si):
Durée d’impulsion :
À 200 ns - 1064 nm PRE = 0 pour F = 1,16 J/cm²
1025 nm-1064 nm
Influence des paramètres laser (sur Si):
Durée d’impulsion :
À 200 ns - 1064 nm PRE = 00
0,1
0,2
0,3
0,4
0,5
0,6
0 200 400 600 800 1000 1200
Fluence (mJ/cm²)
PR
E à
5 t
irs
450 fs-1025 nm
50 ps-1064 nm
4 ns-1064 nm
À 200 ns - 1064 nm
PRE = 0, jusqu’à F = 1,25 J/cm²
SEWG MEETING, Cadarache, June 16th 2009 27/18
1000
800
600
400
200
0
806040200
8000
6000
4000
20001000
800
600
400
200
0
806040200
2000
1500
1000
500
Temperature (K)
Time (ns)
FORTRAN 1D simulation:
Temperature below the fusion threshold
Studies on tungsten particles removal
Temperature (K)
Time (ns)
Depth (µm)
30 shots5 shots
4 ns – 1064 nm – ~700 mJ/cm²
No particle damage 5 shots
1 µm
Particle damage
Collection results are in accordance to FORTRAN simulation Particles could not be ablated
1000
800
600
400
200
0
806040200
2000
1500
1000
500
1000
800
600
400
200
0
100806040200
8000
6000
4000
2000
Depth (µm)
50 ps – 1064 nm – 540 mJ/cm²
Particles not removed Particles not removed
1000
800
600
400
200
0
806040200
8000
6000
4000
2000
2
Fusion (3695 K)
Vaporisation (5828 K)
Temperature above the fusion and vaporization threshold
Possible removal mechanism :
▪ Particle ablation
▪ Explosive evaporation of humidity
▪ Thermally induced expansion
▪ Local substrate ablation
▪ Electrostatic force
SEWG MEETING, Cadarache, June 16th 2009 28/18
1000
800
600
400
200
0
806040200
2000
1500
1000
500
Temperature (K)
Time (ns)
FORTRAN 1D simulation :
Temperature below the fusion threshold
Studies on tungsten particles removal
30 shots5 shots
4 ns – 1064 nm – ~700 mJ/cm²
No particle damage
Collection results are in accordance to FORTRAN simulation Particles could not be ablated
1000
800
600
400
200
0
806040200
2000
1500
1000
500
Depth (µm)
5 shots1 shots No particle damage
27 ns – 248 nm – ~800 mJ/cm²
1000
800
600
400
200
0
806040200
1200
1000
800
600
400
Depth (µm) Temperature (K)
Time (ns)
1000
800
600
400
200
0
100806040200
1200
1000
800
600
400
Particles not removed Particles not removed
SEWG MEETING, Cadarache, June 16th 2009 29/18
C particles at 0.1 Pa, F = 1.6J/cm²
0 500 1000 1500 2000 2500 30000
1
2
3
4
5
6
7
8
9
10
11
12
Si SiO2
d (
mm
)
t (ns)
v = 3800 m.s-1
v = 4240 m.s-1
C particles on Si substrate at 0.1 Pa
(velocity slope of the linear regression curve for 1 µs )
v = 3150 m.s-1
v = 3920 m.s-1
v = 4390 m.s-1
0 200 400 600 800 1000 1200 1400 16000
1
2
3
4
5
6
700 1 1.6
dis
tan
ce (
mm
)
time (ns)
mJ/cm²
J/cm²J/cm²
time (ns)
Dynamic of ejection for carbon particle
Substrate influence: Fluence influence:
▪ These graphs are performed with pictures of the light emitted by the ejected particle or ablated species take with a CCD intensified
SEWG MEETING, Cadarache, June 16th 2009 30/18
0
0,1
0,2
0,3
0,4
0,5
0,6
0 200 400 600 800 1000 1200
Fluence (mJ/cm²)
PR
E à
5 t
irs
450 fs-1025 nm
50 ps-1064 nm
7 ns-1064 nm
Efficacité d’enlèvement – particules de tungstène
Influence des paramètres laser (sur Si):
Durée d’impulsion :
À 200 ns - 1064 nm
PRE = 0, jusqu’à F = 1,25 J/cm²
0 tir 5 tirs
1064 nm – 200 ns - 625 mJ/cm²
1064 nm - 4 ns - ~700 mJ/cm²
1025 nm - 450 fs - ~300 mJ/cm²
0 tir 5 tirs
SEWG MEETING, Cadarache, June 16th 2009 31/18
Outlook
LASK V1
P=10-6PaT= 200°C max
Environment :
Dust collection : adhesion
LASK V2
P=AtmT= 50°C
Environment :
Dust collection : aspiration
These studies help to the elaboration of a removal device based on laser cleaning for Tore Supra. This is a first step for the ITER removal device