Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute...
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Transcript of Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute...
![Page 1: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/1.jpg)
Fracture of Tungsten in a HAPL Chamber
Jake Blanchard
HAPL MWGFusion Technology Institute
University of Wisconsin
September 2003
![Page 2: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/2.jpg)
Outline
• Latest results for crack propagation in tungsten-coated steel walls
• Steel stresses as function of tungsten thickness
• Thoughts on how to measure mass loss in samples
![Page 3: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/3.jpg)
Introduction
• In Albuquerque, I presented a fatigue analysis for a tungsten-coated, steel HAPL wall
• This analysis indicated that surface cracking can be expected within the first hour of operation
• This does not tell us whether cracks will reach the steel (this requires fracture mechanics)
![Page 4: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/4.jpg)
Approach
• Place crack into structural model and calculate stress intensity factor for several crack depths
• If stress intensity goes to 0, cracks will stop
• Otherwise, the stress intensity determines the crack growth rate (per cycle)
• Unfortunately, no crack growth data for tungsten has been found
![Page 5: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/5.jpg)
Fracture Mechanics Analysis of Tungsten Coating
Crack tip
Crack depth Tungsten
Steel
Contact surface
Crack tip stress intensities during thermal cycling calculated using ANSYS J-integral fracture mechanics algorithm
![Page 6: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/6.jpg)
Thermal Response of Structure
Temperature Contours Near Surface at end of
Pulse
6.5 m chamber154 MJ target
No gas50 microns W
![Page 7: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/7.jpg)
Stresses Resulting from Thermal Cycle
Stresses at Maximum Temperature Stresses After Cool Down
MPa MPa
![Page 8: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/8.jpg)
Stress Intensity Variation with Crack Depth50, 100, and 200 m Tungsten coating thicknesses
500 m crack half spacing – single thermal cycle
2
3
4
5
6
7
20 40 60 80 100 120 140
Crack Depth (m)
Str
ess
Inte
nsi
ty (
MP
a-m
1/2 )
50 um W layer
100 um W layer
200 um W layer
![Page 9: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/9.jpg)
Crack Tip Stress Intensity Variation with Crack Spacing
Variation of Stress Intensity with Crack Spacing (Single Cycle)
50 m thick tungsten layer
0
1
2
3
4
5
6
7
8
9
0 50 100 150 200 250 300
Crack half spacing (m)
Str
es
s In
ten
sit
y (
MP
a-m
1/2)
20 um crack
30 um crack
40 um crack
![Page 10: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/10.jpg)
Next Step
• What if crack reaches steel?
![Page 11: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/11.jpg)
Stresses in Steel
• As long as we avoid yielding in the steel, the stress will always be compressive
• Hence, the stress limit will be defined such that yielding is avoided.
• Using the design stress as a limit will ensure this, with a safety factor
![Page 12: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/12.jpg)
Allowable Stresses
Temperature (C) Allowable Stress (MPa)
500 268
650 133
700 111
![Page 13: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/13.jpg)
Latest Results
Chamber radius (m)
Xe Pressure (mTorr)
Target Yield (MJ)
W Thickness (micron)
Peak W Temp in 4 cycles (C)
Peak Steel Temp in 4 cycles (C)
Steel Temp
Swing (C)
Peak Steel Stress (MPa)
6.5 10 154 167 2510 510 85 -300
6.5 10 154 250 2510 480 59 -210
8.5 10 300 167 2410 520 96 -340
8.5 10 300 250 2410 490 65 -240
![Page 14: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/14.jpg)
Conclusions
• Tungsten will crack and cracks may well reach the steel (results are inconclusive)
• Modeling a crack which has reached the steel may not be of any benefit
• Experiments will be the key
• Steel stress requirements lead us to tungsten thicknesses on the order of 200 microns
![Page 15: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/15.jpg)
How to Measure Mass Loss
• Weigh Samples before and after
• Measure Remaining Thickness of Armor (Profilometry, Auger, RBS)
• Measure What Comes Off (Spectrometry/RGA)
• Measure velocity of vapor cloud (shadowgraphy or similar)
• Put layer of trace element at fixed depth
![Page 16: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/16.jpg)
0
1
2
3
4
5
6
7
8
0 50 100 150 200 250 300
Crack half spacing (um)
Str
es
s In
ten
sit
y
30 um crack
Crack Tip Stress Intensity Variation with Time and Crack Spacing
0
1
2
3
4
5
6
7
0.0 1.0 2.0 3.0 4.0
Time (s)
Str
ess
Inte
nsi
ty(M
Pa-
m1/
2)
(MP
a-m
1/2)
Variation of Stress Intensity for a 30 m Crack over 20 Thermal Cycles
Variation of Stress Intensity with Crack Spacing for a 30 m Crack (Single Cycle)
Stress intensity for a 30 m crack in a 50 m thick tungsten layer
100 m crack half spacing
![Page 17: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/17.jpg)
Latest ResultsChamber
radius (m)
Xe Pressure (mTorr)
Target Yield (MJ)
W Thickness (micron)
Peak W Temp in 4 cycles
(C)
Peak Steel
Temp in 4 cycles
(C)
Steel Temp Swing
(C)
Peak Steel
Stress (MPa)
Steel Stress Swing (MPa)
6.5 10 154 100 2510 550 130 -438 410
6.5 10 154 167 2510 510 85 -300 270
6.5 10 154 250 2510 480 59 -210 180
7.5 10 154 100 1840 520 100 -330 310
7.5 10 154 167 1840 480 65 -230 210
7.5 10 154 250 1840 460 45 -160 140
7.5 10 154 500 1840 440 18 -80 55
7.5 10 300 500 3190 470 35 -150 110
8.5 10 300 167 2410 520 96 -340 310
8.5 10 300 250 2410 490 65 -240 100
9.5 0 300 167 2480 510 88 -310 280
9.5 0 300 250 2480 480 59 -212 180
9.5 10 300 167 1890 500 78 -270 250
9.5 10 300 250 1890 480 53 -190 160
![Page 18: Fracture of Tungsten in a HAPL Chamber Jake Blanchard HAPL MWG Fusion Technology Institute University of Wisconsin September 2003.](https://reader035.fdocuments.net/reader035/viewer/2022062802/56649e905503460f94b9491f/html5/thumbnails/18.jpg)
Designs That Work
150 MJ
6.5 meter radius
10 mTorr Xe
250 microns W
300 MJ
8.5 meter radius
10 mTorr Xe
250 microns W