Update on Roughening Work

Jake Blanchard

HAPL MWGFusion Technology Institute

University of Wisconsin

e-meeting – July 2003

Agenda

• Update on Experiment Comparison

• Thoughts on Measuring Mass Loss

• Latest Temperature Predictions

• Initial Fracture Results

• Progress on Paper

Experiment Comparison Table

Experiment Type Energy(keV)

Max Fluence per

Pulse(J/cm2)

Approx Depth of Energy (microns)

Max Starting Temperature

(C)

RHEPP Ions 750 7 1-10 600+

Z X-Rays 0.8-1.2 3000 1-2 1000

XAPPER X-Rays 0.1-0.4 7 1-2 RT+

UCSD Laser 0.7 0 1000

Electra electrons 500 2 100

Infrared Infrared q=10 MW/m2

0

UW IEC Ions 100 Flux=5x10^19 /m2-s

1

Experiment Comparison TableExperiment Max

Sample Size(cm)

Flat Top Pulse Width

(ns)

Rise Time(ns)

Max Rep Rate(Hz)

Max Number Cycles

SampleActively Cooled?

RHEPP 100 NO

Z 6 NO

XAPPER 2.5 diameter

30-50 (FWHM

)

10 1e6 NO

UCSD 1 cm x 1 cm

8 10 3e5 NO

Electra 30 cm x 100 cm

100 40 5 10k/d YES

Infrared >10 ms YES

UW IEC NO

Data to Be Collected in Surface Exposure Experiments

• BASICS– Name of Facility– Name of Experimentalist

• DEPOSITION– Energy Deposition type– Energy Spectrum– Deposition Profile– Fluence per Cycle– Number of Cycles– Pulse Width and Rise

Time

• TARGET– Initial Target Temperature– Target Dimensions– Is the target cooled? How?– Target Material(s)– Material Identifier (Code)– Surface Cleaning Process

• RESULTS– Surface Evaluation Before

and After– Mass Loss– Temperature History

How to Measure Mass Loss

• Weigh Samples before and After

• Measure Remaining Thickness of Armor (Profilometry, Auger, RBS)

• Measure What Comes Off (Spectrometry/RGA)

Latest Temperature Predictions

Chamber radius

(m)

Xe Pressure (mTorr)

Target Yield (MJ)

W Thickness (microns)

Peak W temperature in 10 cycles

(C)

Peak Steel Temperature in 10 cycles

(C)

Steel Temperature

Swing (C)

8.5 10 400 50 3280 820 350

8.5 0 154 50 1820 600 170

8.5 10 154 50 1440 570 140

8.5 0 154 100 1820 520 90

8.5 10 154 100 1440 500 70

7.5 0 154 50 2320 660 230

7.5 10 154 50 1870 620 180

7.5 20 154 50 1530 590 160

7.5 0 154 100 2320 550 120

7.5 10 154 100 1860 530 100

6.5 0 154 50 3100 730 290

6.5 10 154 50 2540 690 240

6.5 20 154 50 2070 660 210

6.5 0 154 100 3100 600 160

6.5 10 154 100 2530 580 140

5.5 10 154 50 3660 800 330

Tcoolant=400 C, h=10,000 W/m2K, steel thickness=3 mm

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

Thermal Response of Structure

Temperature Contours Near Surface at end of

Pulse

6.5 m chamber154 MJ target

No gas50 microns W

Stresses Resulting from Thermal Cycle

Stresses at Maximum Temperature Stresses After Cool Down

MPa MPa

0

1

2

3

4

5

6

7

0 0.1 0.2 0.3 0.4 0.5 0.6

Time (s)

Str

ess

Inte

nsity

(M

Pa-

m0.

5)

Transient Stress Intensity(30 m Crack Depth)

Fracture Mechanics Analysis Results

0

1

2

3

4

5

6

7

8

9

10

10 20 30 40 50

Crack depth (um)

Str

ess

Inte

nsity

(M

Pa-

m0.

5)

• Maximum stress intensities occur at end of cycle (when structure is cool).

• Stress intensity decreases with increasing crack depth

Stress Intensity vs. Crack DepthAfter One Thermal Cycle

Next Steps

• What is effect of crack spacing?

• What if crack reaches steel?

Paper Outline – My Chapter

• 3 Armor (Blanchard)– 3.1 Prompt threats: Expt and modeling of the response of armor

candidates • 3.1.1 ablation; (Expts: Olson, Rank, Tanaka, Latkowski, Najmabadi.• Modeling: Wisc)• 3.1.2 roughening (Expts: Olson, Rank, Tanaka, Latkowski,

Najmabadi.• Modeling: Ghoneim, Blanchard)• 3.1.3 sputtering (Expts ? Modeling: Lucas?)• 3.1.4 Do we gain anything with EW? (Ghoneim, Raffray)

– 3.2 Long term threats: Expt and modeling of the response of armor candidates

• 3.2.1 He retention ( EW: Ghoneim, Solid wall: Snead, Expts: Kulcinski)

• 3.2.2 Modeling: thermo-mechanical fatigue long term effects (Blanchard,. ) 3.2.3 Expts: thermo-mechanical fatigue long term effects (Latkowski, Najmabadi, Raffray, Ghoneim, (SNL?))