Vacuum gauges and their principles of measurement

Abstract

In this text, fundamentals of vacuum measurement are reviewed focused on the operation principles of common (both total and partial) pressure gauges. Total pressure gauges are classified into three categories. The first category includes e.g. U-tube, McLeod, diaphragm and bourdon gauges, which directly measure the actual " pressure" of gases. The second consists of Pirani, thermocouple, thermistor, spinning rotor and quartz gauges, which utilize the transport phenomena of rarefied gases. And the third comprises Penning, cold cathode magnetron, Bayard-Alpert and extractor gauges, which makes use of the ionization phenomena in gases. Partial pressure gages, also known as mass spectrometers, can also be classified into three categories which discriminate the mass of gas molecules 1) electrically, 2) electro-magnetically and 3) by time-of-flight, respectively. In this text, quadrupole mass spectrometer (category 1) and magnetic deflection mass spectrometer (category 2) are discussed in some detail.