M. A. Winkler

Thermophysical properties of solid and liquid tungsten

The thermophysical properties of solid and liquid tungsten have been measured up to an enthalpy ofH = 1.4 MJ · kg−1 using an isobaric expansion technique. These measurements give the pressure, temperature, volume, enthalpy, electrical resistivity, and sound velocity as fundamental quantities. From these, other properties may be calculated, such as specific heat at constant volume and pressure, heat of fusion, isothermal and adiabatic bulk moduli and compressibilities, and thermodynamicγ. Results of these calculations are presented for liquid tungsten and compared with literature values where such data exist. These data will help in understanding liquid-metal phenomenology theoretically and in the design and modeling of exploding wires, foils, and fuses.

Thermophysical properties of molybdenum and rhenium

Thermophysical properties measurements have been made on the metals molybdenum and rhenium at high temperatures and a pressure of 0.2 GPa. These measured properties include volume, temperature, enthalpy, and electrical resistivity. Values for these quantities are shown for both solid and liquid phases. In addition, sound velocities were measured for liquid molybdenum.

Thermophysical properties of POCO AXF-5Q graphite up to melting

Abstract Measurements of the thermophysical properties of a particular POCO graphite (AXF-5Q) have been made up to melting. Results were obtained in two different laboratories using two heating rates. Data for temperature, volume, enthalpy, and electrical resistivity are shown. The measured melting point was found to be 4900 K ± 200 K.

Thermophysical properties of liquid platinum

Material properties of liquid metals are inherently difficult to measure. Static measurements are difficult to make on most metals because of the typically high values of critical temperature and pressure, problems with sample-container contamination, and physical strength limits of high-pressure vessels. Data on thermophysical properties of metals are needed for a variety of applications, and measurements on most liquid metals are performed using dynamic techniques. Dynamic pulse heating experiments are typically performed on nanosecond to millisecond timescales, providing data that would not otherwise be obtainable. We use a resistive pulse heating method to reach high-temperature expanded liquid-metal states at a constant pressure. This technique can be used for a variety of metals and allows accurate data to be obtained over a wide range of temperature. Metallic wire-shaped samples (1×25 mm) are resistively heated in an inert gas atmosphere for a period of about 10−4 s by an almost-square current pulse (∼15×l03 A). Samples expand along an isobaric path, with remote diagnostics providing data on current, voltage, temperature, volume, and sound speed. These basic quantities are then used to calculate several derivative quantities. We report measurements of enthalpy, temperature, volume, electrical resistivity, and sound velocity of liquid platinum for temperatures from the melting point up to ∼5100 K.

Sound speed measurements in liquid lead at high temperature and pressure

Recently sound speed measurements in high temperature liquid lead have been made over a wide density range. Such measurements may be combined with other thermophysical properties measured with the isobaric expansion experiment (IEX) to yield several additional thermodynamic quantities. Results of calculations based on the sound speed measurements are presented, and their impact on liquid metal phenomenology is discussed.

Sound speed in liquid lead at high temperatures

A dynamic technique, the isobaric expansion experiment (IEX), is used to reach high-temperature and pressure states in liquid lead. A unique technique is described for making sound-speed measurements once a final equilibrium end state is obtained. Data over an extended density range are presented. The sound speed in liquid lead over this range appears to vary linearly with density and has no dependence on temperature within our experimental precision (±7 %).

Detection of free surface motion using a masked aperture technique

A new noncontacting technique for measuring the arrival of a stress wave at the free surface of a very hot fluid metal has been developed. By use of an optical lever arm and a coded aperture, the new technique avoids the extreme sensitivity of optical interferometers, while allowing accurate measurement of rapid surface motions.

A Computer Designed Lens by a Nonexpert

This paper describes the approach used by a nonexpert to design a lens by using the LASL lens design code for an IBM 7094 computer. The example lens, the authors first attempt at lens designing, is to be used as an objective in a high-speed rotating-mirror smear camera.

Spherizing a Seven-Power, Wide-Field Eyepiece Design

A seven-power, wide-field, eyepiece design incorporating two paraboloidal surfaces was redesigned. The aspherical surfaces presented a manufacturing problem that precluded large-scale production of an otherwise satisfactory design. The LASL Lens Design Code was utilized to replace the aspherical surfaces with spherical ones and to exceed the performance of the original design. The improved design has allspherical surfaces, and a report on a prototype eyepiece indicates the design to be an excellent one.

Rotating Mirror Vibration

An experimental arrangement is given for measuring the relative amplitude of vibration at any given speed for rotating mirrors. A code is introduced which predicts the frequencies at which resonance occurs for any uniform stepped shaft with a maximum of ten steps. This code is applied specifically to rotating mirrors. Results are then given for a number of rotating mirrors used in various cameras at the Los Alamos Scientific Laboratory.