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Dynamic temperature measurements with embedded optical sensors

Dolan, Daniel H.; Seagle, Christopher T.; Ao, Tommy A.

This report summarizes LDRD project number 151365, \Dynamic Temperature Measurements with Embedded Optical Sensors". The purpose of this project was to develop an optical sensor capable of detecting modest temperature states (<1000 K) with nanosecond time resolution, a recurring diagnostic need in dynamic compression experiments at the Sandia Z machine. Gold sensors were selected because the visible re ectance spectrum of gold varies strongly with temperature. A variety of static and dynamic measurements were performed to assess re ectance changes at di erent temperatures and pressures. Using a minimal optical model for gold, a plausible connection between static calibrations and dynamic measurements was found. With re nements to the model and diagnostic upgrades, embedded gold sensors seem capable of detecting minor (<50 K) temperature changes under dynamic compression.

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TYPE SAND Report YEAR 2013
OSTIDOI

Solid liner implosions on Z for producing multi-megabar, shockless compressions

Physics of Plasmas

Martin, M.R.; Lemke, Raymond W.; McBride, Ryan D.; Davis, Jean-Paul D.; Dolan, Daniel H.; Knudson, Marcus D.; Cochrane, K.R.; Sinars, Daniel S.; Smith, Ian C.; Savage, Mark E.; Stygar, William A.; Killebrew, K.; Flicker, Dawn G.; Herrmann, Mark H.

Current pulse shaping techniques, originally developed for planar dynamic material experiments on the Z-machine [M. K. Matzen, Phys. Plasmas 12, 055503 (2005)], are adapted to the design of controlled cylindrical liner implosions. By driving these targets with a current pulse shape that prevents shock formation inside the liner, shock heating is avoided along with the corresponding decrease in electrical conductivity ahead of the magnetic diffusion wave penetrating the liner. This results in an imploding liner with a significant amount of its mass in the solid phase and at multi-megabar pressures. Pressures in the solid region of a shaped pulse driven beryllium liner fielded on the Z-machine are inferred to 5.5 Mbar, while simulations suggest implosion velocities greater than 50 kms-1. These solid liner experiments are diagnosed with multi-frame monochromatic x-ray backlighting which is used to infer the material density and pressure. This work has led to a new platform on the Z-machine that can be used to perform off-Hugoniot measurements at higher pressures than are accessible through magnetically driven planar geometries. © 2012 American Institute of Physics.

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TYPE Journal Article YEAR 2012
ScopusOSTI
Results 51–75 of 113
Results 51–75 of 113