Dynamic Reflectance of Tin Shocked from Its Beta to BCT Phase

Conference · Mon Jun 01 00:00:00 EDT 2015 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4971713· OSTI ID:1240152

Stevens, Gerald D. ^[1]; La Lone, Brandon M. ^[1]; Turley, William Dale ^[1]; Veeser, Lynn R. ^[1]

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1. Special Technologies Lab. (STL), Santa Barbara, CA (United States)

Shock-induced phase transitions have historically been inferred by features in loading/unloading velocity wave profiles, which arise due to volume or sound speed differences between phases. In 2010, we used a flash-lampilluminated ultiband reflectometer to demonstrate that iron, tin, cerium, and gallium have measureable reflectance changes at phase boundaries. We have improved upon our prior technique, utilizing an integrating sphere with an internal xenon flash lamp to illuminate a shocked metal beneath a LiF window. The new reflectance system is insensitive to motion, tilt, or curvature and measures the absolute reflectance within five bands centered at 500, 700, 850, 1064, 1300, and 1550 nm. We have made dynamic reflectance measurements of tin samples shocked to pressures above and below the beta-BCT phase transition using a light gas gun. Below the transition, the visible reflectance decreases with pressure. At and above the transition, the visible reflectance increases to values higher than the ambient values. Reflectance can therefore be used to locate the beta-BCT phase transition boundary for tin, independent of the velocity wave profile. Using the reflectance data, we also present experimental estimates of the phase fraction as a function of shock stress.

• Research Organization: Nevada Test Site (NTS), Mercury, NV (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: DE-AC52-06NA25946
• OSTI ID: 1240152
• Report Number(s): DOE/NV/25946-2514
• Journal Information: AIP Conference Proceedings, Vol. 1793, Issue 1; Conference: American Physical Society Shock Compression of Condensed Matter Conference Tampa, FL June 14 - 19, 2015 http://www.aps.org/meetings/meeting.cfm?name=SHOCK15
• Country of Publication: United States
• Language: English