Abstract: An air ionizer is provided of the type in which a corona discharge is produced at the point of a sharp `needle` by connecting it to a source of high potential. One or more needles, mounted in an insulator, point in a direction opposite to the eventual flow of air ions. At ions emitted from the point of the needle are reflected by a reflector. The reflector may comprise a sheet of insulating material or an electrically conductive material, e.g. a metal, mounted on insulators. The reflector may be provided with perforations for the passage of air therethrough such that the ionizer may, with advantage, be placed in a moving air stream. The insulator on which the needle(s) is or are mounted may comprise a polythene cable or a printed circuit board.

Abstract: An air ionizer is provided of the type in which a corona discharge is produced at the point of a sharp `needle` by connecting it to a source of high potential. One or more needles, mounted in an insulator, point in a direction opposite to the eventual flow of air ions. At ions emitted from the point of the needle are reflected by a reflector. The reflector may comprise a sheet of insulating material or an electrically conductive material, e.g. a metal, mounted on insulators. The reflector may be provided with perforations for the passage of air therethrough such that the ionizer may, with advantage, be placed in a moving air stream. The insulator on which the needle(s) is or are mounted may comprise a polythene cable or a printed circuit board.