High Pressure Phenomena

This volume reports on the Enrico Fermi School, the first one dedicated to advanced organic materials. The main research results and open problems in science and technology of organic nanostructures have been discussed here - in particular, growth techniques, electronic and optical properties and device applications. The necessary background material has been covered and interdisciplinary aspects have been emphasized with the aim of a unified approach to the basic physical phenomena bridging the gap between standard graduate courses and the state of the art in the field.

In many respects, the science of materials has only fully utilized two of its three fundamental tools - the variables of temperature and chemical composition. Pressure, the third fundamental variable altering materials, is in many ways the most remarkable, as it spans some 60 orders of magnitude in the universe. High-pressure science has experienced tremendous growth, particularly in the last few years. With recent developments in static and dynamic compression techniques, extreme pressure and temperature conditions can now be produced and carefully controlled over a wide range. Moreover, a new generation of analytical probes, many based on third-generation synchrotron radiation sources, have been developed and can now be applied for accurate determination of the structural, dynamical, and electronic properties of matter under extreme conditions. Finally, developments in computational techniques and advances in fundamental theory tested against bountiful new experimental results are both deepening our understanding of materials as a whole and guiding subsequent experimental work with new predictions. It was for this reason that this course on high-pressure science was held at the International School of Physics "Enrico Fermi" School in July 2001. Though presented in a physics forum, the title “High-Pressure Phenomena” was chosen to reflect the broad scope of the field and the diversity of recent findings. Indeed, the field spans fundamental physics and chemistry, materials science and technology, the geosciences, planetary science and astrophysics, as well as biology. The highly interdisciplinary character of the field was central to the organization of the school, though the sheer breadth of the field meant that many topics could be treated in only a cursory fashion while others were examined more in depth. The aim of the school was to present the state-of-the-art in techniques used in modern high-pressure research, highlighting those topics where applications of these techniques are currently having a major impact.

As an editor of the international scienti?c journal Shock Waves, I was asked whether I might document some of my experience and knowledge in the ?eld of blast waves. I began an outline for a book on the basis of a short course that I had been teaching for several years. I added to the outline, ?lling in details and including recent devel- ments, especially in the subjects of height of burst curves and nonideal explosives. At a recent meeting of the International Symposium on the Interaction of Shock Waves, I was asked to write the book I had said I was working on. As a senior advisor to a group working on computational ?uid dynamics, I found that I was repeating many useful rules and conservation laws as new people came into the group. The transfer of knowledge was hit and miss as questions arose during the normal work day. Although I had developed a short course on blast waves, it was not practical to teach the full course every time a new member was added to the group. This was suf?cient incentive for me to undertake the writing of this book. I cut my work schedule to part time for two years while writing the book. This allowed me to remain heavily involved in ongoing and leading edge work in hydrodynamics while documenting this somewhat historical perspective on blast waves.

This monograph deals with the behavior of essentially nonlinear heterogeneous materials in processes occurring under intense dynamic loading, where microstructural effects play the main role. This book is not an introduction to the dynamic behavior of materials, and general information available in other books is not included. The material herein is presented in a form I hope will make it useful not only for researchers working in related areas, but also for graduate students. I used it successfully to teach a course on the dynamic behavior of materials at the University of California, San Diego. Another course well suited to the topic may be nonlinear wave dynamics in solids, especially the part on strongly nonlinear waves. About 100 problems presented in the book at the end of each chapter will help the reader to develop a deeper understanding of the subject. I tried to follow a few rules in writing this book: (1) To focus on strongly nonlinear phenomena where there is no small parameter with respect to the amplitude of disturbance, including solitons, shock waves, and localized shear. (2) To take into account phenomena sensitive to materials structure, where typical space scale of material parameters (particle size, cell size) are presented in the models or are variable in experimental research.

One of the main reasons for continuing interest in shock focusing is its ability to concentrate energy in a small volume and produce extreme temperatures and pressures in fluids in a controlled laboratory environment. The phenomenon of shock wave focusing leading to extreme conditions in fluids during micro- and nanosecond time intervals is a spectacular example of mechanics at small length and time scales revealing the major properties of shock dynamics including high-temperature gas phenomena. Production of high-energy concentrations in gases and fluids with star-like temperatures and extreme pressures by means of a stable imploding shock is of great interest not only in its own right but also because of the connection to a multitude of phenomena in nature, technology and medicine.

This book introduces the core concepts of the shock wave physics of condensed matter, taking a continuum mechanics approach to examine liquids and isotropic solids. The text primarily focuses on one-dimensional uniaxial compression in order to show the key features of condensed matter’s response to shock wave loading. The first four chapters are specifically designed to quickly familiarize physical scientists and engineers with how shock waves interact with other shock waves or material boundaries, as well as to allow readers to better understand shock wave literature, use basic data analysis techniques, and design simple 1-D shock wave experiments. This is achieved by first presenting the steady one-dimensional strain conservation laws using shock wave impedance matching, which insures conservation of mass, momentum and energy. Here, the initial emphasis is on the meaning of shock wave and mass velocities in a laboratory coordinate system. An overview of basic experimental techniques for measuring pressure, shock velocity, mass velocity, compression and internal energy of steady 1-D shock waves is then presented. In the second part of the book, more advanced topics are progressively introduced: thermodynamic surfaces are used to describe equilibrium flow behavior, first-order Maxwell solid models are used to describe time-dependent flow behavior, descriptions of detonation shock waves in ideal and non-ideal explosives are provided, and lastly, a select group of current issues in shock wave physics are discussed in the final chapter.

Since the 1950s shock compression research contributed greatly to scientific knowledge and industrial technology. As a result, for example, our understanding of meteorite impacts has substantially improved, and shock processes have become standard industrial methods in materials synthesis and processing. Investigations of shock-compressed matter involve physics,electrical engineering, solid mechanics, metallurgy, geophysics and materials science. The description of shock-compressed matter presented here, which is derived from physical and chemical observations, differs significantly from the classical descriptions derived from strictly mechanical characteristics. This volume, with over 900 references, provides an introduction for scientists and engineers interested in the present state of shock compression science.

Shock-induced dynamic fracture of solids is of practical importance in many areas of materials science, chemical physics, engineering, and geophysics. This book, by an international roster of authors, comprises a systematic account of the current state of research in the field, integrating the large amount of work done in the former Soviet Union with the work done in the West. Topics covered include: Wave propagation, experimental techniques and measurements, spallation of materials of different classes (metals, ceramics, glasses, polymers), constitutive models of fracture processes, and computer simulations.