Gauges
IONIZATION PRESSURE GAUGES
A high-pressure ionization gauge is described with a novel electrode system of rugged construction. The electrodes consist of two parallel electron collector plates and two parallel ion collector plates mounted at right angles to each other with a filament running axially down the centre. The filament consists of a platinum-10% rhodium wire with an yttrium oxide coating allowing the gauge to operate in reactive gases such as atmospheric air up to a pressure of 5 torr. The evaluation of the gauge characteristics has enabled the optimum operating conditions to be achieved. The gauge sensitivity is equal to 0.11 torr-1 for air and constant within the pressure range 1 torr to 50 torr providing the electron accelerating potential is not greater than 42 V. The gauge can be usefully employed in the pressure range required for applications such as cathodic sputtering, vacuum melting, gas discharge studies, and as a secondary calibration standard. [Summary provided by the Journal of Scientific Instruments]