Gases and Vacuum
In standard conditions at atmospheric pressure, gas serves as an excellent insulator, requiring the application of a significant voltage before breaking down (e.g. lightning). In partial vacuum, this breakdown potential may decrease to an extent that two uninsulated surfaces with different potentials might induce the electrical breakdown of the surrounding gas. This has some useful applications in industry (e.g. the production of microprocessors) but in other situations may damage an apparatus, as breakdown is analogous to a short circuit.
The breakdown voltage in a partial vacuum is represented as :
where is the breakdown potential in volts DC, and are constants that depend on the surrounding gas, represents the pressure of the surrounding gas, represents the distance in centimetres between the electrodes, and represents the Secondary Electron Emission Coefficient. bu
A detailed derivation and some background information is given in the article about Paschen's law.
Read more about this topic: Breakdown Voltage
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