Bulletin of the American Physical Society
22nd Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 67, Number 8
Monday–Friday, July 11–15, 2022; Anaheim, California
Session I03: Diagnostic Development IFocus Recordings Available
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Chair: Tom Hartsfield, Los Alamos National Laboratory Room: Anaheim Marriott Platinum 1 |
Tuesday, July 12, 2022 9:15AM - 9:45AM |
I03.00001: Coherent anti-Stokes Raman Spectroscopy and pyrometry for temperature measurement in ejecta Invited Speaker: Jason Mance We demonstrate the use of Coherent Anti-Stokes Raman Spectroscopy (CARS) and pyrometry to measure temperature in dynamically compressed gases (D2, H2) and ejecta. CARS temperature measurements in pure gases (no ejecta present) are compared to predictions from basic 1-D shock theory which is found to accurately predict the break out properties of the gas shock, though in shocks driven by high explosives significant cooling can occur after breakout that is not accounted for in 1-D models. The gas temperature measurements were made to determine the ambient conditions for ejecta. Pyrometry was also used to measure the temperature of the ejecta. Time-resolved pyrometry measurements of ejecta in these gases show that temperature and emissivity tend to stabilize on a microsecond timescale and equilibrate to temperatures near that expected of the pure gas, except in cases where the metal ejecta is known to chemically react with the gas, in which case ejecta temperature appears hotter than the gas alone would be. |
Tuesday, July 12, 2022 9:45AM - 10:00AM |
I03.00002: Subsurface Spectroscopy of Heterogeneous Materials Using Optical Wavefront Shaping Hergen Eilers, Benjamin R Anderson, Natalie Gese Plastic-bonded explosives and propellants consist of energetic molecular crystals embedded in a polymer matrix that also includes additives, such as taggants, plasticizers, grit, antioxidants, etc. This heterogeneous composition renders these materials optically opaque, limiting optical characterization techniques (e.g., Raman spectroscopy) to probing chemical reactions at the surface. However, many reactions of interest are believed to occur inside the material where current optical techniques can not probe. |
Tuesday, July 12, 2022 10:00AM - 10:15AM |
I03.00003: Quantifying Motion Blur by Imaging Shock Front Propagation Kathryn Harke, Michael R Armstrong, Jonathan Lind, David A Martinez, Mukul Kumar Time-integrated (multiple pulse or longer-time continuous exposure) radiography using MeV Bremsstrahlung x-ray sources is the norm for imaging during system-level testing of components and structures under dynamic conditions. In large scale, dynamic, MeV range experiments, sources of error in the analysis of these datasets stem largely from motion blur. Time-integration very quickly starts to become a problem if the motion (of the compression front) during the additive time and the spatial resolution demanded in the dynamic event become commensurate. In a prelude to applying our methodology to larger scale experiments, we first aim to quantify motion blur on a well understood, small scale experiment, utilizing gas gun capabilities at The Advanced Photon Source’s Dynamic Compression Sector. Both plane wave and reverberating shock wave propagation were investigated experimentally to quantify motion blur and test the validity of our state-of-the-art radiography and hydrodynamic simulation codes. |
Tuesday, July 12, 2022 10:15AM - 10:30AM |
I03.00004: Improving Manganin Gauge Measurements Near Radiographic Fiducials John M Lang, Douglas G Tasker Manganin gauges are fielded in high explosive experiments to measure in situ stresses. Flash X-ray radiography is fielded to measure in situ dynamic flow, requiring radiographic fiducials, typically Ta foil, to be embedded within the experiment. For a more complete in situ measurement of the dynamic event (flow and stress together), manganin gauges are placed in the same layers as the foil fiducials. However, these foils naturally have a high mechanical impedance, and this gauge/foil configuration greatly perturbs the measured dynamic stress. We conducted experiments to test the performance of different arrangements of manganin gauges and Ta foils. Three different gauge/foil configurations were tested, as well as a solitary gauge as control. Gauge/foil layers were placed between high-density polyethylene (HDPE) discs and impacted by a projectile in a gas gun, a simplification of the high explosive experiment configuration. The stress measurements were minimally perturbed when a section of foil was removed near the active element of the gauge, as expected. An experiment is planned to test whether a modification of foil impacts the radiographic measurement of the dynamic flow. |
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