Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session S5: Focus Session: Ejecta Physics V |
Hide Abstracts |
Chair: Robin Williams, AWE Aldermaston Room: Regency Ballroom B |
Thursday, July 13, 2017 9:15AM - 9:30AM |
S5.00001: Proton radiography measurements and models of ejecta structure in shocked Sn J.E. Hammerberg, W.T. Buttler, A. Llobet, C. Morris, J. Goett, R. Manzanares, A. Saunders, D. Schmidt, A. Tainter, W. Vogan-McNeil, C. Wilde We discuss experimental validation of ejecta source mass and velocity models using proton radiography. We have performed ejecta measurements at the Los Alamos proton radiography facility on 7 mm thick 81 mm diameter Sn samples driven with a plane-wave high explosive lens (PBX9501$+$ TNT). The surface of the Sn, in contact with He gas at an initial pressure of 7 atmospheres, was machined to have 4 concentric sinusoidal features with a wavelength of $\lambda =$2 mm in the radial direction and amplitude h$_{\mathrm{0}}=$0.159 mm (kh$_{\mathrm{0}}=$2$\pi $h$_{\mathrm{0}}$/$\lambda =$0.5). The shock pressure was 27 GPa. 42 images were obtained between 0 and 14 $\mu $s from the time of shock breakout at 275 and 400 ns intervals. The Abel inverted density profiles evolve to a self-similar density distribution that depends on a scaling variable z/v$_{\mathrm{s}}$t where v$_{\mathrm{s}}$ is the spike tip velocity, z is the distance from the free surface and t is the time after shock breakout. Both the density profiles and the time dependence of the mass per unit area in the evolving spikes are in good agreement with a Richtmyer-Meshkov instability based model for ejecta production and evolution. [Preview Abstract] |
Thursday, July 13, 2017 9:30AM - 9:45AM |
S5.00002: A Model of a source of shock wave metal ejection based on the mechanism of the Richtmyer-Meshkov instability development Alla Georgievskaya, Victor Raevsky Experimental and calculation studies show that the dominating factor defining characteristics of a shock wave ejection is a surface roughness. We developed the analytical model of the shock wave ejection by considering this process as the consequence of the Richtmyer-Meshkov instability development. The proposed model is based on the assumption that the surface roughness can be represented as periodic sinusoidal perturbations with an amplitude $a_{0} $ (a half of groove depth) and a wave length $\lambda $ (distance from spike to spike between groove). Our model takes into account the effect of a shock break-out pressure, a shock wave profile, the initial amplitude and wave length of perturbations on space-time distribution of density, mass of particles ejected from material free surface, the link between velocities and sizes of particles, particle distribution by sizes. The model has been developed for metals transforming into liquid state after shock wave loading and releasing. We verified our model by comparing its results with the experimental data. It is shown that in liquid phase state of material the shock wave amplitude does not affect the ejected material mass, but is determined by the ratio $\beta =k^{2}\cdot a_{0} \cdot \Delta x$ ($k=2\pi /\lambda $ is a wave number, $\Delta x$ is a triangular shock wave pulse width). Besides, the ratio $\beta $ determines a slope of the function of the particle distribution by sizes. The decrease in $\beta $ at the constant shock break-out pressure leads to displacement of curves of size distributions in the direction of lesser sizes. [Preview Abstract] |
Thursday, July 13, 2017 9:45AM - 10:00AM |
S5.00003: The spikes from Richtmyer-Meshkov instabilities in pused power cylindrical experiments Chris Rousculp, Baolian Cheng, David Oro, Jeffrey Griego, Austin Patten, Levi Neukirch, Robert Reinovsky, Peter Turchi, Joeph Bradley, Wlliam Reass, Franklin Fierro, Alexsander Saunders, Fesseha Mariam, Matthew Freeman, Zhaowen Tang The time evolution of the metal spikes resulting from the Richtmyer-Meshkov instability (RMI) of single-mode perturbations on the inside surface of a tin sample in cylindrical geometry has been measured for the first time. The shock condition was produced by a magnetically driven aluminum flyer utilizing the PHELIX capacitor bank. By varying the flyer velocity, a set of experiments conducted at the Los Alamos National Laboratory has explored the RMI evolution in the different release states (fluid, mixed, solid) of tin. The perturbation inversion and growth rate of the spikes were diagnosed in each experiment with a 21-image proton radiography (pRad) movie. Both theoretical model and numerical simulations are performed. Numerical simulations, theory and experimental data are in good agreement. Detailed analysis of the spike growth rates, comparison to planer geometry, as well as theory and computations will be presented. This work was conducted under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36. [Preview Abstract] |
Thursday, July 13, 2017 10:00AM - 10:15AM |
S5.00004: Unstable 3D phenomena: Dynamic interactions of a cavitation bubble and Richtmyer-Meshkov unstable divot William Buttler, Dru Renner, Chris Morris, Ruben Manzanares, Joel heidemann, Ryan Kalas, Anna Llobet, John Martinez, Jeremy payton, Andy Saunders, Derek Schmidt, Amy Tainter, Samuel Vincent, Wendy Vogan-McNeil We radiographically explore a shock-induced Sn cavitation bubble as it interacts with a transverse cavitation wave caused by a Richtmyer-Meshkov unstable spike from a divot. The cavitation bubble forms as two shockwaves collide under the divot, as the shockwaves release to ambient pressure at the surface. The divot inverts and unstably grows, as expected and predicted, but the release waves that form the cavitation bubble reflect from and constrain the cavitation wave growth. As the cavitation wave grows it pierces the cavitation bubble, deflating it onto the unstable transverse cavitation wave. [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