Pergamon Int. a~ Impact Engng, VoL 20, pp. xiii xiv, 1997

Elsevier Science Ltd Printed in Great Britain

0734-743X/97 $17.00+0.00

T R I B U T E T O J A M E S R. ASAY

Stephan J. Bless

Institute for Advanced Technology University of Texas at Austin,

Austin, TX 78759, U.S.A.

Editor's Note: The following introduced Dr James R. Asay at the 1996 Hypervelocity Impact Symposium, held in Freiburg, Germany, October 1996

When I began my research career in shock physics, Sandia National Laboratory had already established the STAR (Shock Thermodynamics Applied Research) facility as the pre-eminent site for shock physics in the United States. Led by Jim Asay, Sandia had assembled a team of remarkably talented people, with a commitment to evolving new experimental techniques and expertise in the behavior of materials under shock loading, and the momentum of that effort carries forward even to today, when new experimental tools and new models continue to issue from this research group. Thus, it was very satisfying for me to preside over a Committee that decided to select Dr Asay as the recipient of the HVIS Distinguished Scientist Award.

Dr Asay has performed personal research on the study of dynamic material response. He has developed time-resolved shock-wave diagnostics which provided accurate measurements of the mechanical strength of materials under high-pressure shock compression, detection of high pressure solid-liquid phase boundaries using shock-wave techniques, and the use of shock-wave diagnostics to study the kinetics of melting and vaporization. His work demonstrated, contrary to popular belief in the 1970s, that material strength persists in the shocked state, and in fact substantially increases at megabar pressure levels. His development of time-resolved techniques in shock and release studies provided an accurate way to detect melting curves at megabar pressures that have become a standard in the community. These techniques, for example, have been used by other investigators to determine the melting curve of iron at megabar pressures for geophysical studies of the earth. His studies of shock-induced vaporization provided the first data concerning the kinetics of vaporization on nanosecond time scales, and the multi-phase flow characteristics of mixed liquid-vapor phases at ultra-high velocities.

Dr Asay has directed research efforts involving the development of advanced experimental capabilities for shock-wave and ballistic studies, the application of these methods to the study of material response at the extremes of pressure and temperature, and the development of material models and computer codes to simulate these hypervelocity phenomena. He was responsible for initiating programs to develop ultra-high speed launchers, including a three-stage railgun which achieved a record velocity of 7.5 klrdS in a laboratory, and a modified two-stage light-gas gun which has achieved over 12 km/s. His group initiated a computer code development program which resulted in the development of a state-of- the-art hydrodynamics code (CTH) which has become a standard for the impact physics community. His research group also became internationally known for the development of advanced materials models, including the development of fragmentation theories. He was active in promoting the integration of Sandia activities with other organizations and helped to develop collaborations with organizations, such as NASA- JSC, NASA-MFSC, DNA, Boeing Aerospace, Teledyne Brown, DARPA, ARL, SwRI, Caltech, Brown University and others.

For the past three years, Dr Asay has been involved in program development and technology transfer activities at Sandia National Laboratories. He participated in strategic planning for the transfer of weapons technologies to the U.S. private sector and in developing new initiatives with the former Soviet Union.

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xiv Tribute

This latter program involved partnering between U.S. industry, several DOE national laboratories, and institutes in the former Soviet Union to achieve long-term economic and political stability in the new republics. Now Dr Asay is once again intimately involved in impact studies at the revitalized STAR facility.

Dr Asay graduated from Washington State University in 1971 with a PhD in Physics. He also holds degrees from the University of New Mexico (MS in Physics) and from San Jose State University (BS in Physics). He has published over 100 technical papers on the subjects of shock wave experimental techniques and the dynamic response of materials; he has also written a book on shock compression techniques. He has participated on several national and international committees, including a National Academy of Science appointed Panel to evaluate the space debris hazard and recommend long-term solutions to NASA.

He is a Fellow of the American Physical Society, a Fellow of the Institute of Advanced Technology at the University of Texas, and President and a member of the founding Board of Directors for the Hypervelocity Impact Society. He has been Chairman of the Aeroballistic Range Association and has served on several committees in that organization. As ARA Chairman, he instituted separate secretary and treasure functions. He is also past Chairman of the American Physical Society Topical Group on Shock Compression of Condensed Materials.

Editor's Note." Dr Asay's Distinguished Scientist Keynote presentation starts' on page 2 7 of this volume