Tungsten Thermionic Emission as a Gauge for Low Pressures of Cesium Vapor

TL;DR

This paper investigates tungsten thermionic emission as a method to measure low cesium vapor pressures, presenting experimental results and improved gauge designs for accurate pressure assessment in alkali metal environments.

Contribution

It introduces a novel thermionic emission gauge for cesium vapor pressure measurement and demonstrates its effectiveness through proof-of-principle experiments.

Findings

Thermionic emission varies with cesium vapor pressure and filament temperature.

A second-generation gauge design improves measurement accuracy.

Experimental validation confirms the gauge's potential for alkali metal vapor pressure measurement.

Abstract

Heated metal filaments under electric fields and low pressures of alkali metal gaseject electrons by thermionic emission as a function of the pressure of the gas and thetemperature of the filament. To explore this process in a program to develop large-area alkali metal photocathodes, we have designed and built a gauge following thestudies of Taylor and Langmuir. We present proof-of-principle measurements ofthe thermionic emission of a tungsten filament in cesium vapor. We describe a secondgeneration design that corrects flaws in the first gauge.