Hollow needle-to-plate electrical discharge at atmospheric pressure

Ecological applications dealing with the cleaning of flue gases, the decomp osition of volatile hydrocarbons and the destruction of toxic pollutants re quire, in order to reach high efficiency, the use of non-thermal plasma sou rces. Typical sources of such non-equilibrium plasmas are barrier discharge , direct current (DC) or alternating current (AC) gliding are, pulsed or DC corona and DC atmospheric pressure discharge stabilized by a fast gas Row (APD-GFS). In case of APD-GFS the gas Rows in a rectangular channel, the to p wall of which serves as the anode and the multi-needle cathode is built i nto the bottom wall of the channel. In order to prevent the transition to a spark and to stabilize this type of discharge the velocity of the gas shou ld be about 100-200 m s(-1) or the discharge current must be limited. To av oid the problem connected with the acceleration of the primary (polluted) g as at such a velocity, the external Row of the primary gas around the needl e electrodes can be superimposed by a Row of a secondary gas through the ne edles. Thus the primary gas need not be accelerated to high velocity and in order to stabilize the discharge a relatively small amount of a secondary gas supplied through the needle is required. This work is therefore focused on the study of the DC APD-GFS in hollow needle-to-plane geometry. The bas ic electrical characteristics, magnetic noise and integral emission spectra of this type discharge with the flow of nitrogen or air through the needle are given.