Low Temperature Physics i Kltephysik i

High pressure science is a rapidly growing diverse fi. e1d. The high pressure technique has become a powerful tool for both the study and preparation of materials. In spi. te of the many high pressure conferences held in recent years, I felt that there was a need for scientists within a well-defined area (not bound merely by the common experimental technique) to meet in an atmosphere conducive to frank exchange and close interaction. In this spirit, the Cleveland State University hosted such a conference from July 20 to 22, 1977, in which the physics of solids under high pressures and at low tempera­ tures was specifically examined. Both the original and review papers presented at the conference and the candid discussions following their presentations appear in this volume. They clearly cover a rather complete spectrum of current research in the physics of solids at high pressures and low temperatures. I wish to thank the National Aeronautics and Space Administra­ tion, the Office of Naval Research and the National Science Founda­ tion for their financial support of the conference. In addition, I wish especially to thank Steinar Huang for his unceasing assistance in arranging this conference. I also wish to thank him and Francis Stephenson for their assistance in preparing this book. C. W. Chu, Chairman, International Conference on High Pressure and Low Temperature Physics v Contents HYDROGEN AND METAL-HYDRIDES (Chairman: I. Spain) PROSPECTS FOR METALLIC HYDROGEN 1 A. L.

71 For a given value of I the field is independent of the geometrical composition of the coil inside the winding space. The actual number of turns and the cross­ section of the conductors is entirely determined by the impedance of the power supply to which the magnet should be adapted. In the case of low impedance (high current and low voltage) few turns of thick metal should be used. In the case of high impedance (low current and high voltage) many turns of thin material are needed. High impedance coils are made of square wire or flat strip wound into layers or "pancakes" 1. A nice system for low impedance coils was deve­ loped by BITTER. The turns of his magnets consist of flat copper discs separated by thin insulating sheets and joined together at their edges. In this type of coil the current density is higher near the axis than at the exterior, resulting into a higher value for G (see above). For the details of the construction we refer to the original papers 2, 3. If the power is dissipated at a low voltage the cooling may be achieved with the help of water. Distilled water should be preferred over mains' water in order to prevent the magnet from corrosion. In the case of a high voltage coil some non-inflammable organic fluid should be used. A low viscosity and a large specific heat are advantageous.

High pressure science is a rapidly growing diverse fi. e1d. The high pressure technique has become a powerful tool for both the study and preparation of materials. In spi. te of the many high pressure conferences held in recent years, I felt that there was a need for scientists within a well-defined area (not bound merely by the common experimental technique) to meet in an atmosphere conducive to frank exchange and close interaction.

Presents experiment, theory and technology in a unified manner. Contains numerous illustrations, tables and references as well as carefully selected problems for students.

Fundamental Tests of Physics with Optically Trapped Microspheres details experiments on studying the Brownian motion of an optically trapped microsphere with ultrahigh resolution and the cooling of its motion towards the quantum ground state.

The revised second edition of this practical book reviews the fundamentals of cryogenic liquid behaviour in small and large scale storage systems. The text is based on research findings on the convective and evaporative behaviour of cryogenic fluids, aimed at improving the design, construction and operation of low-loss cryogenic liquid storage systems, with a view to minimising cost and improving operational safety.