A plasma doping method and a plasma doping apparatus, having a superior in-plane uniformity of an amorphous layer formed on a sample surface, are provided. The device presents its output as a standard bridge configured differential signal, which can be interpreted and measured using conventional electronic demodulation means. The impeller is driven for rotation by the output shaft of the motor and includes a plurality of vanes in communication with the at least one pumping channel. Each protrusion defines a cavity extending therethrough. The event of interest includes information relating to a thread to which the instruction is bound. The wherein the magnetic brush is separated from the latent image carrier outside the development area.