PULLMAN — A team of physicists from WSU has successfully completed the first experiments using the nation’s premiere synchrotron X-ray facility to detect shock wave-induced changes in a crystalline material.
The Advanced Photon Source (APS) at Argonne National Laboratory, near Chicago, provided the most detailed view yet of what happens to a crystal lattice that is struck by a solid object at high velocity.
“We just made history in shock wave research with these experiments at the APS,” said Yogendra M. Gupta, director of the Institute for Shock Physics at WSU. He said he expects the use of synchrotron x-rays to measure the effects of shock waves to revolutionize research in the field.
In the APS experiments, a specially-designed ‘gun’ launched half-inch diameter aluminum cylinders at a velocity of about half a kilometer per second (more than 1100 miles per hour) at test materials such as lithium fluoride and aluminum. The shock waves from the impact produced stresses in the samples tens of thousands times greater than atmospheric pressure, and deformed the crystalline structure of the materials.
To detect minute changes in the structures, about 100 billionths of a second after the shock wave passed through the material, the synchrotron sent a pulse of x-rays directed to the sample material. The material diffracted (or scattered) the x-rays to varying degrees depending on the alterations to its structure.
Previous experiments in shock physics have used x-ray sources that cause the x-rays to fan out slightly as they travel to the sample, resulting in a certain fuzziness of the resulting image. Gupta said the Advanced Photon Source producesa tightly-focused beam of x-rays, providing much finer resolution of the crystalline structure of the shocked material.
The gun and diagnostic equipment used in this experiment were designed and built at Washington State University, shipped in parts to Argonne, and assembled there by the WSU team. The WSU experimental team was led by Stefan Turneaure and included Choong-Shik Yoo, Kurt Zimmerman, Kent Perkins, Cory Bakeman, and Nate Arganbright. Design, testing, sample preparation, and the experimental runs took more than a year. The experiments were conducted over a six-day period by the WSU Team with technical support from G. Shen, project manager of the High Pressure Collaborative Access Team (HPCAT) at the APS, and other HPCAT staff members.