Conduction of Electricity in Gases

Abstract

The conduction of electricity through gases has played ubiquitous roles in science and technology. It was responsible for many of the fundamental discoveries in atomic and molecular physics; gas discharge lighting is essential to every night operations; gas discharge lasers are still important in research and manufacturing; and all of advanced microelectronics depends on plasma enhanced processing. To a large extent, the efficiencies of the above cited applications of gaseous electronics depend on the maintenance of the distinct non-equilibrium between the electrons and the gas or vapor. This non-equilibrium can be achieved by operating at low pressures or under pulsed excitation, where the duration of the energy input is less than the energy equilibration time between the electrons and the heavy particles. The term gas discharge originally described a transient or spark condition, but has been extended to mean the continuous conduction of electricity through gases. Section 87.1 treats the electron-velocity distribution and its effect on various measurements involving a swarm or distribution of electron velocities. In this section, low fractional ionization (<10−6) is assumed; electron-ion collisions are negligible relative to electron-atom (and electron-molecule) collisions in so far as they affect electron mobility, diffusion or energy loss. Section 87.2 introduces the glow discharge and considers the cold cathode and hot cathode discharge phenomena. Section 87.3 discusses ionization by electron collision, electron attachment, ion mobility, ion-ion and electron-ion recombination, and other important processes that affect the conduction of electricity in gases. Section 87.4 illustrates the importance of gaseous electronics with several important phenomena and technical applications.