Bulletin of the American Physical Society
19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015; Tampa, Florida
Session C3: Velocimetry II: PDV Analysis and Energetics |
Hide Abstracts |
Chair: Ed Daykin, National Security Technologies, Michael Furlanetto, Los Alamos National Laboratory Room: Grand G |
Monday, June 15, 2015 11:15AM - 11:30AM |
C3.00001: Initiation Train Experiments Elizabeth Francois, Carl Johnson, Gary Liechty, Von Whitley In an effort to evaluate and qualify a new detonator diagnostic, booster selection and main charge configuration, a variety of small-scale tests have been conducted. This paper will describe the needs, testing approach and model validation. Because of the limited size available some novel approaches were made to understand the observed phenomenon. Function time and time of arrival at various locations in the initiation train are desirable data points. Knowing when each segment initiates the next segment and the time to run up to detonation is critical. Results of our experiments were modeled for timing accuracy, wave shape and pressure. Agreement between the experiments and models will be discussed. The testing that will be discussed is time of arrival wires, PDV, and fiber optic arrays. The time of arrival wire measures the detonator cup breakout time. When correlated to bridge burst, an absolute time is collected. This data point also gives time zero for the booster initiation. Many models actually start at the booster, rather than the detonator, so the inclusion of this data point will improve modeling efforts [Preview Abstract] |
Monday, June 15, 2015 11:30AM - 11:45AM |
C3.00002: Characterizing the growth to detonation in PETN and HNS with small-scale PDV cutback experiments Ryan Wixom, Cole Yarrington, Robert Knepper, Alexander Tappan, Joseph Olles, Matthew Zelenok For many decades, cutback experiments have been used to characterize the equation of state and growth to steady detonation in explosive formulations. More recently, embedded gauges have been used to capture the growth to steady detonation in gas-gun impacted samples. Data resulting from these experiments are extremely valuable for parameterizing equation of state and reaction models used in hydrocode simulations. Due to the extremely fast growth to detonation in typical detonator explosives, cutback and embedded gauge experiments are extremely difficult, if not impossible. Using frequency shifted photonic Doppler velocimetry (PDV) we have measured particle velocity histories from explosive films impacted with electrically driven flyers. By varying the sample thickness and impact conditions we were able to capture the growth from inert shock to full detonation pressure within distances as short as 100 $\mu $m. These data were used to assess and improve burn-model parameterization and equations of state for simulating shock initiation. Additionally, we discuss details of the experiment and data analysis regarding the most accurate possible determination of the velocity spike. [Preview Abstract] |
Monday, June 15, 2015 11:45AM - 12:00PM |
C3.00003: The Effect of Post-Burst Energy on Exploding Bridgewire Output Elizabeth Lee, Mike Bowden For an EBW detonator, as the fireset energy is increased from threshold to all-fire level the post-burst energy delivered to the detonator increases, and the function times decrease. To gain an understanding of the processes through which the post-burst electrical energy influences the function times the effect of the post-burst energy on the explosion of bridgewires was studied. A fireset was developed which enabled the post-burst energy to be varied independent of the burst energy by terminating the current flow at pre-selected times. The effect of this on the bridgewires was characterised at a range of firing voltages and a range of termination times. The response of the bridgewire was characterised using Photonic Doppler Velocimetry. The velocimetry trace detected two families of velocities. The first family had initial velocities in the range 1-2 km.s$^{-1}$ and the second family had velocities in the range 0-0.5 km.s$^{-1}$. The relative position of the two families depended on the post burst energy. The results show that a reduction in the post-burst energy and therefore the total delivered energy, but for a constant energy delivered to burst, corresponds to a decrease in the acceleration and peak velocity of the bridgewire / plasma at burst. [Preview Abstract] |
Monday, June 15, 2015 12:00PM - 12:15PM |
C3.00004: Advanced PDV velocity extraction Daniel Dolan, Tommy Ao, Michael Furnish While PDV has become a standard diagnostic, reliable velocity extraction remains challenging. Measurements with multiple real/apparent velocities are intrinsically difficult to analyze, and overlapping frequency components invalidate standard extraction methods. This presentation describes an advanced analysis technique where overlapping frequency components are resolved in the complex Fourier spectrum. Practical matters---multiple region of interest selection, component intersection, and shock transitions---will also be discussed. [Preview Abstract] |
Monday, June 15, 2015 12:15PM - 12:30PM |
C3.00005: A Data-Driven Approach for Determining Time of Initial Movement in Shock Experiments using Photonic Doppler Velocimetry Marylesa Howard, Abel Diaz Photonic Doppler velocimetry (PDV) is a high-speed, interferometric technique for measuring the beat frequency of a moving surface, from which the calculated velocity profile of the surface can be used to describe the physical changes the material undergoes after high-impact shock. Such a technique may also be used to characterize the performance of small detonators and determine the time at which initial movement was recorded. Hundreds of PDV probes may be deployed at a time on an experiment, and extracting the time at initial movement for each probe becomes an arduous task. In this work, we develop a semi-automated technique for extracting the time at initial movement from a normalized lineout of the power spectrogram near the offset frequency of each multiplexed-PDV probe. We characterize the response bias of this method and compare with the time obtained by hand calculation of the raw voltage data. Results are shown on shock experiments from gas gun setups and explosives-driven flyer plates. [Preview Abstract] |
Monday, June 15, 2015 12:30PM - 12:45PM |
C3.00006: Uncertainty in Laser Doppler Velocimetry Measurements Patrick Younk Laser Doppler velocimetry, also known as photonic Doppler velocimetry (PDV), is a diagnostic commonly used in shock compression experiments. To quantitatively compare experimental results to computational results, the uncertainty in the velocimetry measurements must be well characterized. That is, we must know which features in the experimental data are statistically significant and which are not. In this talk, I will present recent work on understanding the precision, accuracy, and resolution of PDV measurements. I will discuss how the uncertainty is a function of signal strength, signal digitization, noise (both white and structured), sampling frequency, and sampling period, and how the uncertainty is influenced by the analysis method. I will show how a knowledge of uncertainty can be used to rigorously compare experiment with computational predictions. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700