Abstract: An improved waveguide window (10) for use in high power waveguide applications. The window (10) preferably includes a thin sheet (12) of dielectric material having a first planar face (14), a second (16) face, and a support structure (18) attached to the first face (14) to provide mechanical support for the sheet (12). The support structure (18) preferably includes a plurality of parallel conductive support bars (20), each bar having an inner portion (22) attached to the first face (14) and an outer portion (24) extending away from the sheet (12), the outer portion (24) being tapered to minimize wave reflection. At least one bar (20) also has a channel (28) bored therethrough to allow a coolant to flow through the bar (20) to remove heat generated within the dielectric sheet (12). Together, the sheet (12) and the support structure (18) form a waveguide window (10) which may be used to environmentally separate one waveguide section (32) from another (34).

Abstract: In a gyrotron cavity resonator, generated energy is extracted into a symmetric set of fundamental-mode waveguides by ports disposed to couple energy in phase from the operating electromagnetic mode but in anti-phase with respect to an unwanted mode of lower cutoff frequency than the operating mode, thereby neutralizing coupling to the unwanted mode. A second set of interspersed ports may be disposed to load degenerate, orthogonal modes.

Abstract: A gyrotron interaction resonator 29 operating in a TE.sub.n1 cavity mode has an array of longitudinal slots 32 in the conductive wall 30. The slots 32 are spaced to couple to the unwanted TE.sub.n1 modes and to other modes of differing n and not to the desired mode. Wave-absorptive material 34 spaced from the inner cavity wall 28 and coupled to slots 32 absorbs the unwanted modes.

Abstract: In a gyrotron microwave tube, electromagnetic leakage through beam-transmitting drift tubes is greatly reduced by making the diameter of the drift tubes in centimeters less than 8.8 divided by f where f is the operating frequency in gigahertz.

Abstract: For conducting very high microwave power at very high frequencies, circular waveguide transmitting a circular-electric-field mode is used. The vacuum-tight window of an electron tube is often the element with lowest power-handling capability. The inventive window has two dielectric plates with a space between them. There is a gap in the waveguide inner wall through which a dielectric fluid is circulated between the plates to cool them. The gap leads to a region containing wave-absorbing material such as water to absorb modes other than the circular-electric-field mode.