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In an ionographic device projecting a modulated stream of ions in imagewise fashion towards a moving imaging surface, including an ion printing head having an ion chamber supporting a coronode held at a voltage VC to produce ions for deposit on an imaging surface and a modulation channel extending f

In an ionographic device projecting a modulated stream of ions in imagewise fashion towards a moving imaging surface, including an ion printing head having an ion chamber supporting a coronode held at a voltage VC to produce ions for deposit on an imaging surface and a modulation channel extending from the ion chamber towards the imaging surface through which a stream of ions is directed for imagewise modulation by a plurality of modulation electrodes, electric field distribution within the ion chamber is controlled by selectively varying voltages along the surface regions of the ion chamber to different voltage levels, in an arrangement causing focusing of ion density in the area of the ion chamber adjacent to the modulation channel. An increased ion density in the area of the ion chamber adjacent to the modulation channel assists in providing an increased corona current at the output of the device.

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In an ionographic imaging device including an ionographic head for depositing an image pattern of ions on an imaging surface, the ionographic head including an ion source held within an ion chamber formed in the head, a modulation channel extending generally from the ion chamber towards the imaging

In an ionographic imaging device including an ionographic head for depositing an image pattern of ions on an imaging surface, the ionographic head including an ion source held within an ion chamber formed in the head, a modulation channel extending generally from the ion chamber towards the imaging surface, through which ions pass in a stream for imagewise modulation prior to deposit on the imaging surface, and means for enhancing the efficiency of said ion source to increase the proportion of ions generated at the ion source that are directed through said modulation channel, said enhancing means comprising: means for segmenting the head into a plurality of head regions, each region forming a portion of the ion chamber; means for providing a voltage potential on each region, the voltage on each region selected so that the magnitude of an electric field extending outwardly from the ion source within the ion chamber is greatest in the direction of the modulation channel.