Materials Studies on Z

Materials Studies on Z

T. J. Tanaka, T. J. Renk, G. A Rochau, and C. L. Olson Sandia National Laboratories*

Dec. 5 and 6, 2002Naval Research Laboratory, Washington DC

*Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

Outline

• Results from last 6 months– W, W/Re, W/La2O3 Ion Beam Secondary Electron

Microscopy• Future work

– Z machine, heated samples– Fast closure valve on Z– Saturn-spectrum and yield– Materials

Fluence and Samples on ZFiltering Fluence SampleNo Filter 19 J/cm2 W, W/Re,

2 m Kimfol +.1 m Al

2.3 J/cm2 W, W/Re, W/LaO

2 m Kimfol + .1 m Al + 2.5m

Be

1.3 J/cm2 W, W/Re, W/LaO

2 m Kimfol + .1 m Al + 4.0 m Be

.98/cm2 W, W/Re, W/LaO

No Filter

2 m Kimfol +.1 m Al

2 m Kimfol + .1 m Al + 4.0 m Be

2 m Kimfol + .1 m Al + 2.5m Be

Ion Images W

Unexposed

Exposed to 19 J/cm2Exposed to 2.3 J/cm2

Exposed to 1.3 J/cm2

Pancake grains

Columnar grains

Platinum coating

DebrisCrater

Bottom of melted region

Ion images from Michael Rye and Joe Michael

A close look at debris craterW at 19 J/cm2

The crater bottom had traces of Fe, Ni and Cr. Surface must have been somewhat crystallized before impact of debris

Ion Images W75%Re25%

Exposed to 2.3 J/cm2 Exposed to 19 J/cm2

Exposed to 1.3 J/cm2Unexposed sampleColumnar grains

Pancake grains

Ion Images, W99%/La2O31% by Weight

Exposed to 2.3 J/cm2

Unexposed sample

Exposed to 1.3 J/cm2

Exposed to 0.98 J/cm2

Platinum coating

Depth of Molten Layer from FIB

Fluence (J/cm2)

Pure W W/25%Re W/1%La2O3

19 1.3 ± 0.1 m 1.2 ± 0.2 m No sample

2.3 0.4 ± 0.1 m 0.7 ± 0.2 m 1 ± 0.3 m

1.3 0 0 0

Using optical surface profiling, changes in the surface of the samples that melted were observed. The top surface was roughened at 19 and 2.3 J/cm2, but no obvious vaporization

Conclusions

• From C. Olson’s presentation, fluence levels that caused roughening in samples appear melted in ion cross-section images.

• Differences between W and W/25%Re include change in melting point and original grain size. These differences may account for discrepancy in apparent melt depth.

• Standard cross sectioning may be needed to view any

Future Work

• Sample preheat to 500 to 700 ° C• Debris mitigation with Fast closure valve• Saturn as a possibility for x-ray exposures• Material selection through Lance Snead, ORNL

Debris Mitigation with a Fast Shutter

Electromagnet or coil

PositionerAluminum Tube (Shutter)

Line of Sight

Catcher

•Electromagnetic shutter developed for Backlighter experiments on Z

•Shutter is in regular operation

•Modification of front collimator and material holder needed to provide correct collimation and heating of samples

Information from Dean Rovang

Saturn Spectrum and Yield

0100200300400500600700800900

2.5 3 3.5 4 4.5

Photon energy (KeV)

Inte

nsity

35-30 kJ of K-shell yield250 kJ ± 15% total yield

Information from Christine Coverdale

Saturn has less energy, is not used as much as Z, and costs less. Z produces more debris.