Abstract: A method of preventing a high-frequency noise generated in an electronic device, remaining in a grounding cable as a standing wave and transmitted to electric devices, is disclosed, which method including disposing, directly or via an insulating layer, a non-metallic conductive material having a slight electric resistance, on a conductor of the above-mentioned grounding cable, making the electric resistance of the non-metallic conductive material consume the high-frequency noise flowing on the conductor surface of the grounding cable by virtue of a skin effect, whereby resonance of the high-frequency noise is reduced. Resonance of the high-frequency noise generated from various electronic devices in an office building and the like can be easily reduced. Consequently, various disadvantages due to high-frequency noise can be avoided.

Abstract: In the gyrotron apparatus of the present invention, the microwave absorbing unit is provided around the insulation cylinder located between the microwave reflecting transmitter and the collector so as to electrically insulate them from each other, and constituting a part of the vacuum chamber. With this structure, the leakage of an unnecessary microwave to the outside through the insulation cylinder, which may occur when the apparatus is operated with a reduced potential of the collector with regard to the transmitter, can be more surely suppressed.

Abstract: In a gyrotron apparatus, an oscillator tube unit and a collector are coupled by a bellows. The collector is received in an evaporation boiler jacket. The oscillator tube is supported on a stand and the collector and the boiler jacket is supported on the other stand.