Outgassing is the release of trapped gas or vapor that are dissolved, trapped, frozen, or absorbed in the materials being heat-treated in a vacuum system. Outgassing includes sublimation and evaporation which are phase transitions of a substance into a gas, as well as desorption. Increasing outgassing during vacuum pump-down forces adsorbed/absorbed gas/vapor to enter the gaseous phase so that it can be pumped out of the chamber. This is achieved by heating the chamber AKA Baking, bake-out, or baking out are common terms used within the industry.
“There are four main ways you can reduce outgassing in your vacuum system. These are: cleaning and handling, surface treatment, passivation, and purging, and backfilling. In this blog, we will take a closer look at each of these methods.”
Source: Vacuum Science World