USA As Represented by Secretary of the Navy

Achintya K Ganguly

Kwo R Chu

Kenneth L Davis

Yuval Carmel

Michael E Read

Carter Michael Armstrong

Denis C Webb

Jin J Choi

A folded waveguide gyrotron-traveling-wave-amplifier comprises: an electron gun for transmitting an axis-encircling beam of electrons with large transverse energy along a first path having an axis; an RF source for producing and applying in a second path an RF input millimeter wave signal having a bandwidth in a preselected frequency domain and having a transverse electric field; a source for generating a solenoid magnetic field parallel to the axis along the first path; a beam collector; and an interaction circuit such as an H-plane bend serpentine waveguide positioned within the solenoid magnetic field and having a narrow wall containing a beam tunnel hole for passing the axis-encircling beam of electrons therethrough to the beam collector, an output end, and an input end for receiving and passing the RF input millimeter wave signal through the H-plane bend serpentine waveguide to the output end to modulate the axis-encircling electron beam, the modulated axis-encircling electron beam amplifying the RF input signal and also broadening the instantaneous bandwidth of the amplified RF input signal through the negative mass instability in the fundamental forward space harmonic of both fast and slow wave regions in the preselected frequency domain. In a second embodiment, a double-ridged TE folded waveguide is used in place of the H-plane bend serpentine waveguide. In a third embodiment, there is no RF input signal and the interaction circuit generates an RF signal which is outputted from one of the input and output ends.

High power, broadband folded waveguide gyrotron-traveling-wave-amplifier

A complex cavity gyrotron designed for stable operation at high order modes. The device comprises circuitry for generating an annular electron beam, a coupled cavity disposed coaxially with the electron beam and having a first and second adjacent coaxial sections with the dimensions of these coaxial sections adjusted so that different modes with the same azimuthal eigen number but different radial eigen numbers are simultaneously resonant at approximately the same frequency in the two sections, and circuitry for generating an axial magnetic field within the cavity. Few, if any, combinations of modes other than the combination chosen will simultaneously resonate in the cavity thereby effecting higher order mode suppression. The present design has a low susceptibility to beam velocity spread and is effective for any combination of modes with identical azimuthal eigen numbers.

Complex cavity gyrotron

A magnetron in which the space between the anode and cathode contains a h mobility semiconductor. The structure is non-cylindrically symmetric because the anode and cathode are placed on top of the semiconductor. The electrons are injected into the substrate and then accelerated toward the anode members where they are extracted. Alternate anode members are strapped together to favor excitation of the .pi.-mode.

Solid state magnetron

A solid-state cyclotron maser for generating low power (1 watt or less) signals in the submillimeter frequency range (300 GHz-30,000 GHz) includes an accelerating region, a drift region, and a metal grid therebetween. Both regions are formed from semiconductor material, such as indium antimonide, having non-parabolic energy bands. The drift region is a thin disc having metallized outer surfaces, but includes an annular opening in the metal on the front side and a circular opening in the metal on the back side, and is grounded. A grid of metal rings is placed on the annular opening of the drift region. The accelerating region is a hollow cylinder having a metallized front surface. It couples to the drift region for covering the annular opening and the grid. A negative bias voltage is applied to the accelerating region and a magnetic field is applied to the maser at an angle to the axis of the maser. Electrons propagate in spiral trajectories through the accelerating region, grid and drift region. Movement of electrons within the non-parabolic energy bands of the semiconductor material causes changes in the effective mass of the electrons. Phase-bunching of electrons occurs and electrons radiate coherently. Energy is removed from the drift region at the opening on its back side.

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Alexandria, VA, United States of America

Achintya K Ganguly