Abstract: An apparatus for exciting a gas, comprising at least a pair of electrodes connecting to an alternating current source in a housing having an inlet opening for a gas to be treated and an outlet opening for a gas which has been treated, characterized in that one electrode of the pair of the electrodes is a suspended electrode arranged by placing it under a tension at a predetermined position in the housing, the other electrode of the pair of the electrodes is a buried electrode arranged at a predetermined position by being buried in the holding wall of the housing at the end thereof, an electrode portion of the buried electrode contains a linear or planar discharging portion as a whole, and the electrode portion of the suspended electrode, opposed to the electrode portion of the buried electrode, has discharging portions where a distance from the electrode portion of the buried electrode becomes cyclically short.

Abstract: An apparatus for exciting a gas, comprising at least one pair of electrodes connecting with an alternate current electric source in a housing having an inlet opening for the gas to be treated and an outlet opening for a treated gas, the pair being a combination of a protected electrode and a protected electrode, or a combination of a protected electrode and an exposed electrode, wherein at least one protected electrode is composed of a core electrode with an insulating coating layer carried thereon and covering an entire surface thereof is disclosed.