Bulletin of the American Physical Society
18th Biennial Intl. Conference of the APS Topical Group on Shock Compression of Condensed Matter held in conjunction with the 24th Biennial Intl. Conference of the Intl. Association for the Advancement of High Pressure Science and Technology (AIRAPT)
Volume 58, Number 7
Sunday–Friday, July 7–12, 2013; Seattle, Washington
Session D3: NT.1 Novel Techniques: Flyers and Guns |
Hide Abstracts |
Chair: Anthony Fredenburg, Los Alamos National Laboratory Room: Fifth Avenue |
Monday, July 8, 2013 1:45PM - 2:00PM |
D3.00001: Development of an accelerating-piston implosion-driven launcher Justin Huneault, Jason Loiseau, Andrew Higgins The ability to soft-launch projectiles at velocities exceeding 10~km/s is of interest to several scientific fields, including orbital debris impact testing and equation of state research. Current soft-launch technologies have reached a performance plateau below this operating range. The energy and power density of high explosives provides a possible avenue to reach this velocity if used to dynamically compress a light driver gas to significantly higher pressures and temperatures compared to light-gas guns. In the implosion-driven launcher (IDL), linear implosion of a pressurized tube drives a strong shock into the gas ahead of the tube pinch, thereby forming an increasingly long column of compressed gas which can be used to propel a projectile. The McGill IDL has demonstrated the ability to launch a 0.1-g projectile to~9.1 km/s. This study focuses on the implementation of a novel launch cycle wherein the explosively driven pinch is accelerated down the length of the tube in order to maintain a relatively constant projectile base pressure early in the launch cycle. The experimental development of an accelerating driver which utilizes an explosive lens to phase the detonation wave is presented. The design and experimental performance of an accelerating-piston IDL is also discussed. [Preview Abstract] |
Monday, July 8, 2013 2:00PM - 2:15PM |
D3.00002: Enhancing Impact Speed with Shock Interactions in a Restricting Die William Anderson, Brian Jensen, Frank Cherne, Charles Owens, Kyle Ramos, Mark Lieber There is a need to increase the impact velocities that can be achieved with gun systems used for impact and shock compression studies. Two-stage guns normally required for high-velocity studies are expensive and relatively rare, while most single-stage guns have modest performance (0.2-2 km/s) that limits their utility for high-pressure and high-velocity studies. In this work, we are developing a technique that uses a low-strength sabot, coupled with a restricting die, to increase the impact velocity without modifying the gun itself. Impact of the projectile with the die, which is typically attached to the muzzle of the gun, generates shock waves in the sabot that interact to accelerate the front of the projectile, while decelerating the rear portion. The performance achieved by this technique is greater than would be expected from a simple nozzle working on a fluid with the properties of the sabot. Preliminary experiments using this technique have observed a velocity enhancement of close to a factor of two. The performance that can be achieved is critically dependent on the stress field geometry and we are currently developing a set of models and calculations to optimize this system. [Preview Abstract] |
Monday, July 8, 2013 2:15PM - 2:30PM |
D3.00003: Integrity of high-velocity water slug generated by an impacting technique Sevda Dehkhoda, Neil Bourne A pulsed~water jet is a series of discrete water slugs travelling at high velocity. Immediately after striking a target, these slugs apply high-intensity, short-duration transient stress known as the water hammer pressure, followed by low-intensity, long-duration stationary stress at the stagnation pressure. The magnitude and duration of the water hammer and stagnation pressures are controlled by the size and quality of the water slugs. The use of water jets for rock cutting in mining operations is a centuries-old technology; however, practical methods for producing high-energy water slugs repeatedly have proven~difficult. This can be partly due to the fact that the geometrical properties of a jet and so its effectiveness in creating damage is controlled and influenced by the method that is employed to generate the water slugs. This paper investigates the integrity of a single water slug produced using an impacting technique where a hammer strikes a piston, resting on top of a water-filled chamber. The coherence of the generated water pulse was of concern in this study. If repeated shock reflections within the chamber were transmitted or were carried into the internal geometry of nozzle, the emerging jet could pulsate. The impact impulse of the formed water jet was measured in a Kel-F target material using an embedded PVDF (Polyvinylidene fluoride) shock gauge. The recorded stress waveform was then used to study the quality and endurance of the water pulse stream as it travelled through air. [Preview Abstract] |
Monday, July 8, 2013 2:30PM - 2:45PM |
D3.00004: Ramp Wave Generation Using Graded Areal Density Ceramic Flyers and the Plate Impact Technique Peter Taylor, Gareth Appleby-Thomas, Michael Goff, Paul Hazell, James Leighs, David Wood Ramping shock waves of the order $\sim$ 2-4 GPa were generated in Kel-F targets through the use of graded areal density ceramic flyers via the gas gun plate impact technique, with a buffer disc employed between the flyer and the target to eliminate penetration by the ceramic flyer. Ramp wave parameters were varied through alteration of the areal density gradient and the thickness of the buffer disc used. Observations of the ramped shock were undertaken through the use of embedded particle velocity gauges and the results compared with hydrocode calculations. The discussion of results includes details of the magnitude, gradient and planarity of the ramp waves produced at various positions in the target material. The flyers were fabricated from alumina ceramic with the ceramic laser stereo-lithography process. In order to characterise the material for modelling purposes a series of shots were carried out to compare the Hugoniot of this material with conventionally sintered material, these results are presented. [Preview Abstract] |
Monday, July 8, 2013 2:45PM - 3:00PM |
D3.00005: A novel graded density impactor Ron Winter, Matthew Cotton, Ernest Harris, Daniel Eakins, David Chapman Ramp loading using graded-density-impactors as flyers in plate impact experiments can yield useful information about the dynamic properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to fabricate a graded-density flyer, termed the ``bed of nails'' (BON). A 2mm thick x 100mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6mm and spaced 1mm apart. Two experiments to test the concept were performed at impact velocities of 900m/s and 1100m/s using the 100mm gas gun at The Institute of Shock Physics, Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7mm, mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in free surface velocity over a period of about 2.5 microseconds. The measured profiles have been analysed to generate a stress vs. volume curve for tantalum. [Preview Abstract] |
Monday, July 8, 2013 3:00PM - 3:15PM |
D3.00006: Modelling the Equation of State of a Graded Density Impactor Geoffrey Cox, John Maw There is a requirement for off-Hugoniot data to validate material models. One technique is to use projectiles with graded shock impedance layers in a gas gun to impact a target and apply a ramp loading. To accurately design a shock profile to be applied to the target the impactor should be modelled. This also provides an assessment of whether lateral rarefactions will hinder the experiment, and increases confidence in the analysis of the results obtained. This talk considers several methods for calculating the equation of state of particulate mixtures for application to the modelling of graded density impactors. [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