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346 Design of a Cesium Vapour Pressure Gauge Based on Electronic Thermionic Emission

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Description: We describe the design and underlying principles of a tungsten-filament gauge for the partial vapor pressure of cesium. Operation is based on the temperature depen- dence of electronic thermionic emission from a tungsten filament with a thermally equi- librated partial coverage of cesium, which increases with vapor pressure and decreases with filament temperature. Due to the reduction of the work function of thermionic emission, the current from the filament is a measure of the coverage. By fitting the curve of emission versus filament temperature to a theoretical model, the cesium va- por pressure is obtained. We explain the physical principles behind the device, and describe the construction, operation, and calibration of a prototype built to test the performance of this concept. We document the construction, operation, and calibra- tion of the gauge and analyse the differences between the predicted and experimentally measured data. Based on the analysis, we elaborate on how to design this gauge to obtain better data on desired thermionic emission.

Joao Francisco Shida
Eric Spieglan
Fangjian Wu
Mesut Caliskan


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Uploaded By: PSEC author