Table of contents

The theoretical basis and the important design features of infrared radiation thermometers are described, together with some applications of the technique.

A new inclination detecting method is proposed. When a vessel changes its posture, the magnetic fluid in the vessel is deformed, and its deformation is a function of the incline. A trial inclinometer with a differential transformer was manufactured. The differential transformer transmits the magnetic fluid deformation into an AC voltage output. The experimental results show linearity in the range 0-9 degrees of inclination.

A simple and versatile pre-mixer which can be coupled to a stopped-flow apparatus is described, allowing the concentration of one substance to be varied in 16 equal steps. It can also be used for the generation of relatively long-lived transient species. Its materials permit operation with corrosive chemicals such as bromine solutions. The device is constructed in such a way that contamination of the stock solutions is impossible. The reproducibility of the dilution values was found to be excellent.

The application of the generalised hot-wire technique to high pressure thermal conductivity measurement is discussed. Results for the thermal conductivity of NaCl obtained with a wire sandwiched between two homogeneous discs, one of NaBr and one of NaCl, were recorded in the pressure range 0-4 GPa. The results obtained are compared with those for a homogeneous cell. This comparison indicates that the generalised hot-wire technique appears to be applicable to high pressure thermal conductivity measurement. However, the errors in the generalised technique are larger than those in the standard technique.

Describes a novel method for determining the thermal product ( rho ck)^1/2 for thin film or surface thermocouple type heat transfer gauges. The method utilises optical technique using a known power laser. The values of ( rho ck)^1/2 so obtained compare favourably with those obtained by previous investigators.

The electrical theory and equivalent circuit of an inductive and electrodeless conductivity device are described. Predictions based on theory are compared with measurements using fluid samples of known conductivity. The general trend of the device response as the frequency is varied is shown to agree with theory. A simple model of the induced current flow in the fluid sample is proposed which relates the electrical properties of the device to the conductivity of the fluid in which it is immersed.

A method that allows measurement of high mechanical quality factors (Q) of bodies made of insulating materials is described, whereas the sample is arranged as the dielectric in two independent capacitors. This allows one to apply an electric force to the sample and to measure the resulting displacement without the need to apply conductive coatings. An example is presented whereby a Q of 88000 has been measured for a cylinder made of fused silica.

This study is concerned with a method of reflectometry for the testing and characterisation of two-terminal networks in a frequency band that stretches over more than three decades (0.3-500 MHz). The device is a resistive network, provided with a wide-band high-sensitivity detector, as well as low-noise and low-frequency electronics for the measurement of the moduli of incident reflected and total waves. Consequently the characteristics of all two-terminal networks are determined on a broad band of frequencies in less than one second.

Nearly universal experimental circuitry is described for driving surface-stabilised ferroelectric liquid crystal devices (SSFLCDs), linear arrays and matrix arrays. The circuitry uses only standard CMOS electronics and allows testing and optimisation of different addressing and switching concepts which are discussed briefly. Due to its programming flexibility the circuit is also useful for driving liquid crystal devices applying other technologies, for example TN devices.

An inexpensive apparatus using the eddy current decay method for measuring the resistivity from bulk samples is described. In order to rapidly accumulate data on the variation of the eddy current, the analogue signal is digitised and stored in a specially developed fast transient device (FIFO). The digital data are then transferred to a microcomputer for further analysis. The resistivity of an Al-1.56 at.% Cu alloy has been measured using this apparatus in order to determine the solute concentration after different aging times at 210 degrees C.

An automated Hall profiling system is described which enables the carrier concentration and mobility profiles of semiconductor layers to be obtained at both room and liquid nitrogen temperatures. The system uses chemical stripping of the layers and the differential Hall effect technique. As many semiconductor devices operate at 77 K, valuable information on the electrical properties of the material at this temperature can be obtained. Typical examples of this are presented for both the III-V and II-VI compound semiconductor systems.

The authors report incontrovertible evidence of the first direct observation of ferromagnetic images in iron-core electromagnet vibrating sample magnetometers (VSMs) and determine their magnitude. They demonstrate experimentally that the ferromagnetic image strength at low field approaches that of the magnetic sample source moment and find image contributions of up to 25% in one typical VSM system studied. Quadrature image formation in nonmagnetic (Cu) plates in the proximity of the detection coils and pole pieces is also investigated. As a consequence of the observations reported it is clear that failure to account for images in electromagnet VSMs can lead to underestimating the induced signal by up to 100%.

Using a commercially available optical displacement meter, the deflection caused by magnetostriction is measured. A displacement sensitivity of 0.1 mu m enables magnetostriction as low as 4*10^-7 to be measured in a 1 mu m thick film. Two different probes are used to measure deflection when an applied magnetic field is rotated in the film plane and when rotated in a plane perpendicular to the film. Two parameters, lambda ₁₀₀ and lambda ₁₁₁, can be obtained from measurements using two probes. The measured value of the Ni film showed agreement with reported bulk values within 10%.

An inverse photoemission spectrometer is described which combines momentum resolution for measurements done with low energy incident electrons (photon energy range 12-44 eV) and momentum integration for high energy studies in the isochromat mode (photon energy 14896.6 eV). This unique combination makes it possible to maximise surface sensitivity, enhance bulk sensitivity, and identify the orbital angular momentum character of specific unoccupied states through variations in photoionisation cross section. Experimental capabilities are included for characterisation of ordered, disordered and reactive overlayers deposited in situ on metal and semiconductor surfaces. Representative results are presented for interfaces formed by depositing Fe onto cleaved surfaces of the high temperature superconductor La_1.85Sr_0.15CuO₄.

A new low-cost x-ray cell allowing in situ study of solid transformations in gaseous flowing reactants at 293-473 K is described and its potential is illustrated by results for reduction of unsupported CuO in flowing hydrogen at 398 K.

An apparatus for conducting small-scale wind tunnel experiments is described, in which extension of the usual lower velocity range is derived from use of a reticulated metal resistance in the working section and a programmable microstepping motor.

The feasibility of using sheathed thermocouples as heater elements for temperatures of up to 900 degrees C has been explored. Type K (nickel-chromium/nickel-aluminium) thermocouples with Monel sheath have been used. For thermocouples of 1 and 1.55 mm diameter up to about 150 and 200 W respectively can be dissipated provided the precaution of a heat sink at the electrical connection is taken. Sheathed thermocouples offer a convenient solution to a variety of heater problems.

Three types of miniature vacuum seal are described which will be of interest to cryostat builders. Their use is demonstrated in the construction of a cryogenic siphon which can be assembled and dismantled at will by the use of screw couplings, there being no need to solder and unsolder joints. Two of the three types function at liquid helium temperature.

The relationship between linear pressure and flow as quantified by the Hagen-Poiseuille equation, for gas flow through a capillary and utilised in the design of the flow control system described. The system is essentially a servo-operated pressure controller feeding a capillary discharge tube. In this case the proportional integral (PI) control algorithm is implemented in software but this is not essential. This design is offered as a low-cost alternative to mass flow metering systems and has the additional benefit of easy calibration to any required gas.