1 / 9

RHEPP Tungsten Update

RHEPP Tungsten Update. Tim Renk Sandia National Laboratories Beam Applications & Initiatives Department HAPL Program Workshop Atlanta, GA February 6, 2004. Supported by NRL by the HAPL program by DOE NNSA DP.

derron
Download Presentation

RHEPP Tungsten Update

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. RHEPP Tungsten Update Tim Renk Sandia National Laboratories Beam Applications & Initiatives Department HAPL Program Workshop Atlanta, GA February 6, 2004 Supported by NRL by the HAPL program by DOE NNSA DP 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.

  2. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 400 shot Map N shots on Tungsten (Room Temperature): Roughening only above threshold • Polished W exposed to 400 shots N beam: 1.0 < fluence < 3.7 J/cm2 • Room Temp (RT) exposure • Roughening occurs above 1.25 J/cm2, consistent with single-shot reflectometer roughening threshold • Powder Met Mo (one point at 2.5 J/cm2 ): roughness stays near unexposed value • Above threshold, roughening is a severe function of fluence. Maximum Ra exceeds 22 µm, with P-V height above 70 µm

  3. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 W (Powder Met) roughening: SEM images as function of shot number: 60 to 1000X (N 60X @ 6 J/cm2) (N 250X @ 2.5 J/cm2) He 450X @ 1-1.3 J/cm2) (N 600X @ 4.0 J/cm2) (N 1000X @ 2.5 J/cm2)

  4. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 60-shot exposure of PM W (500C) @ 6 J/cm2: Resolidification from 2-3 µm depth, consistent with SIM modeling, no cracking Hi-Mag image, showing uniform single-xtal (right) and disordered single-xtal (left) In depth grains (N 1000X @ 2.5 J/cm2) Simulation results: Melt Depth: 2.3 µm Melt Duration: 627 ns MaxTemp: 6648K I.e. above ablation threshold (for 65 ns) Ra = 0.4-0.6 µm Ablation step: 1-2 µm (165 - 330Å/pulse)

  5. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 XTEM of 60X-treated PM W (right) show no cracking in depth Bright-Field TEM image TEM image from 5 µm depth

  6. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 FIB-XTEM of 1000-pulse W at 2.25 J/cm2 (ave): Deep horizontal/vertical cracking without melt • Polished Powder Met W exposed to 100 shots N beam @ 2.25 J/cm2 ave /pulse, ~ melting temperature at surface. No melt layer observed. • 600°C exposure • Sample cracking horizontally/vertically down to 10 µm depth • Suspect fatigue-cracking Near-surface 5 - 10 µm depth

  7. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 FIB-STEM of 1000-pulse W at 2.25 J/cm2 (ave): No melting or recrystallization evident Near-surface 5 - 10 µm depth Simulation results: Melt Depth: 0.2 µm Melt Duration: 91 ns MaxTemp: 3752K (from 600C) Ra = 2.3 - 4.5 µm

  8. Pulsed Power Sciences, Sandia National Laboratories TJR 2/4/2004 We may have an alternative ‘Foam’ Supplier Source: Center for Collaborative Research/Research Center for Advanced Science and technology (CCR/RCAST) Prof. Tatsuhiko Aizawa • Type1: W-25Re alloy, cell-structured No carbon, only W-25Re alloy Column thickness: 50-100 µm Pore: < 50 µm • Type 2: W-25Re Alloy, honeycomb No carbon, only alloy column thickness: 100 µm • Prof. Aizawa to visit SNL March 22, 2004

  9. Pulsed Power Sciences, Sandia National Laboratories TJR 11/25/03 Summary • Tungsten: surface roughening excessive (PowderMet), with fatigue cracking below surface maybe even worse. Mitigating: CVD/SingXtal, alloying with Re, heating. Cracking looks like enough to compromise performance as armor coating. • Roughening occurs over hundreds of shots. Topology may stabilize for W by 1000 shots, looks to increase for other metals beyond this. • Below the roughening threshold (1.25 J/cm2), W may be topologically stable to repeated ion exposure. • No W recrystallization below melting temp appears to take place • Both 60X-6J/cm2 and 1000X-2.5J/cm2 sample response consistent with SIM modeling • Next: treatment of W on SiC, extended treatment of various samples to 2,000 shots

More Related