Deionization of a Gas

the disappearance of carriers of free electric charge (positive and negative ions and electrons) from the volume occupied by a gas. Deionization results from the recombination of ions and electrons, their diffusion toward the boundaries of the volume occupied by the gas, and the extraction of the charged particles by an external electrical field applied to the gas. The time required for decreasing the charge-carrier concentration by a given multiple (for example, to 10^-3 or 10^-6 of the initial concentration) is called the deionization time, which is an important characteristic of gas-discharge instruments and other instruments in which ionization of gas takes place, such as gas-filled current rectifiers, thyratrons, ignitrons, antenna switches, and charged-particle counters. The deionization time depends on the nature of the gas, the geometry of the volume occupied by the gas, the presence and change with time of an external electric field, and the distribution of the spatial charge fields.