A 7.2 keV spherical x-ray crystal backlighter for two-frame, two-color backlighting at Sandia’s Z Pulsed Power Facility

• Published in: Review of scientific instruments Vol. 88; no. 10; pp. 103503 - 103510
• Main Authors: Schollmeier, M. S., Knapp, P. F., Ampleford, D. J., Harding, E. C., Jennings, C. A., Lamppa, D. C., Loisel, G. P., Martin, M. R., Robertson, G. K., Shores, J. E., Smith, I. C., Speas, C. S., Weis, M. R., Porter, J. L., McBride, R. D.
• Format: Journal Article
• Language: English
• Published: United States 01.10.2017
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.4994566

Many experiments on Sandia National Laboratories’ Z Pulsed Power Facility—a 30 MA, 100 ns rise-time, pulsed-power driver—use a monochromatic quartz crystal backlighter system at 1.865 keV (Si He α ) or 6.151 keV (Mn He α ) x-ray energy to radiograph an imploding liner (cylindrical tube) or wire array z-pinch. The x-ray source is generated by the Z-Beamlet laser, which provides two 527-nm, 1 kJ, 1-ns laser pulses. Radiographs of imploding, thick-walled beryllium liners at convergence ratios C R above 15 [ C R = r i ( 0 ) / r i ( t ) ] using the 6.151-keV backlighter system were too opaque to identify the inner radius r i of the liner with high confidence, demonstrating the need for a higher-energy x-ray radiography system. Here, we present a 7.242 keV backlighter system using a Ge(335) spherical crystal with the Co He α resonance line. This system operates at a similar Bragg angle as the existing 1.865 keV and 6.151 keV backlighters, enhancing our capabilities for two-color, two-frame radiography without modifying the system integration at Z. The first data taken at Z include 6.2-keV and 7.2-keV two-color radiographs as well as radiographs of low-convergence (C R about 4-5), high-areal-density liner implosions.