gas discharge

gas discharge [¦gas ′dis‚chärj]

(electronics)

Conduction of electricity in a gas, due to movements of ions produced by collisions between electrons and gas molecules.

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Gas discharge

A system made up of a gas, electrodes, and an enclosing wall in which an electric current is carried by charged particles in response to an electric field, the gradient of the electric potential, or the voltage between two surfaces. The gas discharge is manifested in a variety of modes (including Townsend, glow, arc, and corona discharges) depending on parameters such as the gas composition and density, the external circuit or source of the voltage, electrode geometry, and electrode material. See Electrical breakdown

Gas discharges are useful both as tools to study the physics existing under various conditions and in technological applications such as in the lighting industry and in electrically excited gas lasers. New applications in gas insulation, in high-power electrical switching, and in materials reclamation and processing will assure a continuing effort to better understand all aspects of gas discharges. See Laser

Electrons, rather than ions, are the main current carriers in gas discharges because their mass is smaller and their mobility is correspondingly much higher than that of ions. Electrons are produced by ionization of the gas itself, or they originate at the electrodes present in the system. Gas ionization can be accomplished in several ways, including electron impact ionization, photoionization, and associative ionization. Bombardment by photons, energetic ions or electrons, and excited neutral particles can cause secondary emission from the electrodes. A high-energy-per-unit electrode surface area can induce thermionic or field emission of electrons. Each of these means of producing electrons leads to a different response of the gas discharge as a circuit element. See Electrical conduction in gases, Electron emission, Field emission, Ionization, Photoemission, Secondary emission, Thermionic emission