Abstract: In a substantially circular waveguide constituting a mode converter in a gyrotron tube, there is a region whose transverse inner surface shape changes to a non-true circular shape from a true circular shape in a range of 0 mm to 5 mm toward a radiation aperture from the incident side. Therefore, an undesirable cavity resonator which causes parasitic oscillation can be prevented from being formed in the vicinity of an inlet of the mode converter. Therefore, the parasitic oscillation of the mode converter can be suppressed, and a conversion efficiency of the converter can be enhanced, because of the effective length of the mode converter can be enhanced in the limited actual length.

Abstract: In a substantially circular waveguide constituting a mode converter in a gyrotron tube, there is a region whose transverse inner surface shape changes to a non-true circular shape from a true circular shape in a range of 0 mm to 5 mm toward a radiation aperture from the incident side. Therefore, an undesirable cavity resonator which causes parasitic oscillation can be prevented from being formed in the vicinity of an inlet of the mode converter. Therefore, the parasitic oscillation of the mode converter can be suppressed, and a conversion efficiency of the converter can be enhanced, because of the effective length of the mode converter can be enhanced in the limited actual length.

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.

Abstract: There is provided a gyrotron including a quasi-optical mode converter wherein a solid dielectric layer such as silicon carbide for absorbing unnecessary millimeter waves generated by diffraction of the quasi-optical mode converter is arranged in annular shape in the periphery of the quasi-optical mode converter, and millimeter absorption fluid can be supplied to the periphery of the mode converter in a predetermined direction through vacuum barrier walls formed by a dielectric member, thereby efficiently absorbing the diffracted millimeter wave which is the cause of generating heat.