JP2867628B

PURPOSE:To nullify noises generated from power supplies substantially by using a battery to each power supply for a neutralizing means, and thereby eliminating rotund-in of noises from an AC line. CONSTITUTION:A filament 8 is installed on the side of a Faraday case 4 in order to prevent electric discharge or the like because of positive charging on the surface of a base board 5 associate with irradiation with an ion beam 2, and the primary electrons 11 emitted therefrom are allowed to bombard the inner wall of the Faraday case 4. Thereby secondary system 12 is emitted, and the positive electric charges with the ion beam 2 are neutralized. Batteries 14a, 16a, 18a, 20a are used to a filament power supply 14, emission power supply 16, holder bias power supply 18, and Faraday bias power supply 20, respectively, which supply power to a neutralizing means for the described purpose. From the battery 14a, power is supplied to the filament 8 via a filament current control circuit 28, which controls the filament current under control by a neutralization control circuit 24. Because these control circuits 28, 24 lead directly to the Faraday system, batteries 28a, 24a are used also to these power supplies.