This basic course was planned and arranged by the Education Division, the Vacuum Society of Japan for students and beginners who start engaging in vacuum science and technology in either research or business fields. The course is also intended to be a preparation text for the Vacuum Summer School and is made up of four lectures; molecular gas dynamics, vacuum and surface, evacuation process and vacuum pumps, and vacuum measurement.
To understand the property of gases, it is essential to consider them using kinetic theory of gases. This theory assumes that gas atoms/molecules are freely travelling and frequently changing their speed and direction by collisions each other. The purpose of the present article is to try to introduce the basic concepts of kinetic theory of gases to readers. We also show how it explains the fundamentals of vacuum science such as idealgas laws, origin of pressure, surface impinging rate and mean free path.
Any vacuum chamber has interior surfaces of the chamber facing toward the vacuum. Interaction of gas molecules with the chamber surface including scattering, adsorption and desorption is thus of particular importance for vacuum technology. The present article describes fundamental concepts of gas-surface interaction, which encompass the thermal accommodation coefficient, cosine law, adsorption potential, mean time of sojourn and adsorption isotherm.
Presented here are the fundamental concepts of evacuation process and the key features of various vacuum pumps. Several essential terms, including evacuation time constant, pumping speed and conductance, are introduced to help the understanding of evacuation mechanism and to enable the design of vacuum systems. The vacuum pumps are systematically classified with their operating principles, structures and characteristics. It will help readers to select the proper vacuum pumps and to realize the reasonable vacuum system in different situations.
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.
An extreme high vacuum (XHV) pumping system has been produced with a chamber made of 0.2 % beryllium copper alloy. The system is evacuated by using a newly developed pill-type nonevaporable getters (NEG) combined with an entrapment pump. It is also equipped with our original ion gauge and low outgassing residual gas analyzer compatible with XHV. When you use this XHV pumping system, pressures in the 10−10 Pa range can be achieved within 24 hours from the atmospheric pressure.