ABSTRACT
The word ‘vacuum’ originates from the Latin word ‘vacuus’ which means ‘vacant’ or ‘empty’. Foundation for vacuum technology is ‘vacuum science’ and it is known to comprise of phenomena and laws governing generation and sustenance of vacuum. Turbo molecular pumps are easy to operate and assure clean, oil free vacuum. An important mechanism of attaining vacuum is by removing gas molecules using ‘Gettering’ or chemisorption. Instruments used for carrying out quantitative measurements of vacuum are called vacuum gauges. The vacuum gauges can be classified on the basis of measuring technique involved. At lower vacuum, corresponding higher pressures can be measured directly using gauges based on direct force measurements and hence called ‘direct gauges’. The phenomenon of ionization is exploited to create indirect type of vacuum gauges namely ionization gauges. Ultra high vacuum is necessary for fields such as particle physics, semiconductor technology etc.
