Polycrystalline, CVD and Single Crystal Tungsten Heated samples on Z Tina Tanaka, Greg Rochau, Robert Peterson, and Craig Olson June 2-3, 2004 HAPL Meeting at UCLA Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Outline Discrepancy on fluence levels Previous data Images from most recent work Corrected fluence data What more needs to be included in calculations What we plan to do next

Data conditions for Dec 2003 Z exposures Samples from Dec 2003, heated to 600º C An aperture was added to the front of sample box to reduce debris and lower scattered flux Be filters were used with all samples

Discrepancy on Fluence Levels Investigated Discrepancy noted on April 13 conference call regarding fluence Corrected fluence data—Fluence much lower than first predicted Problem was with mass absorption coefficients There are still questions on the spectrum because there is a high energy tail which contains 6 to 10% of the energy The tail will not be filtered as much as lower energies (more energy?) The energy will deposit deeper into the sample (less melting?)

Previous (2002) Data: Polycrystalline W Unheated W 1.3 J/cm J/cm 2 19 J/cm 2 2  kimfoil 2.5  Be  Al 2  kimfoil 0.1  Al No Filters No effect 0.5  melted2  melted

Dec 2003 data: Polycrystalline W 0.64 J/cm 2 8  Be No Effect Unexposed

Dec 2003 Data: More Polycrystalline W 0.61 J/cm 2 8  Be No Effect 0.11 J/cm 2 10  Be + 2  Mylar No Effect

Dec 2003 Data: CVD W Unexposed 0.64 J/cm 2 8  Be No Effect

Dec 2003 Data: More CVD W 0.61 J/cm 2 8  Be No Effect 0.11 J/cm 2 10  Be + 2  Mylar No Effect

Dec 2003 Data: Single Crystal W 0.64 J/cm 2 8  Be No Effect Unexposed

Dec 2003 Data: More Single Crystal W 0.61 J/cm 2 8  Be No Effect 0.11 J/cm 2 10  Be + 2  Mylar No Effect

Experimental Data Range of next tests

BUCKY Calculations Have Been Performed for Heated Tungsten Z Experiments Spectrum from Z783 (single array w/o foam). He “filter” for now. Scaled spectrum to a given fluence; parametric search. W initial temperature = 100 C°. Results: Vaporization Threshold  2 J/cm 2. Melting Threshold  1 J/cm 2. Future: Get dynamic hohlraum radial spectrum. Use correct Filters. Use radial radiation temperature versus time from Si diode arrays.

X-ray Energy Determines Depth of Heat Deposition These depths are distances for which the intensity of x-ray energy falls to 1/e. 1-2 keV is about the peak of the Z spectrum using filters. Calculated for solid W.

X-ray Spectrum on Z Typically Has a “Second” Blackbody Tail Transmission Grating Spectrometer grating source Silicon PIN detectors Filtered carbon XRD detectors Filtered PCD detectors G. A. Chandler, et al., RSI, 70, 561 (1999) L. E. Ruggles, et al., RSI, 72, 1218 (2001) R. B. Spielman, et al., RSI, 68, 782 (1997) source S TGS (0.47  0.08)E 3 expE/(162  7)   1 S PCD  (8.7  4.1)exp  E/(619  55)  E (> 1 keV) ≈ 20 ± 6 kJ/ster P pk (> 1 keV) ≈ 20 ± 6 TW XRD  MEC, 10/01 Single Z pinch

What’s Next? Check beryllium-filtered shots from 2002 Unfold spectrum accurately for dynamic hohlraum (which we have been using) Calculate melting for unfolded spectrum Get more data near the melting threshold—Z run June 9, 2004