V. Ayres

Microwave generation from a cusptron oscillator with a six-vane circuit

Microwave radiation at high harmonics of the electron cyclotron frequency is generated from a cusptron device. An axis-rotating beam of 30kV, 3.5 A, 4μs, and 60pps interacts with modes in a six-vane circuit by the negative mass instability. Radiation power is more than l0kW with approximately 10% electronic efficiency at 6·0GHz which corresponds to the sixth harmonic of the electron cyclotron frequency. With the same circuit and a 28xa0kV, 1·5 A beam, we also obtained approximately 40kW radiation with 9·5% efficiency at the fourth harmonic frequency of 3·9xa0GHz

Dispersion characteristics of cusptron vacuum waveguide modes

With successful demonstration of the ‘proof-of-principle’ experiment of the cusptron, the configuration of the cusptron waveguide gains importance. Although the dispersion relation for the cusptron rf circuit has been derived and experimentally verified before, the detailed properties of its dispersion characteristics are not well understood. In this paper, we will examine various aspects of the dispersion properties in conjunction with the design process of the cusptron tubes. In particular, two unique properties of the cusptron rf circuit, the mixture and the specific grouping of the azimuthal mode numbers are closely examined and demonstrated with simple physics. Special emphases are on the identification and designation of the modes, the profiles of various field components, the spectral distribution with respect to azimuthal mode numbers, and their relation to the cusptron microwave tube design

Preliminary study of cusptron amplifier

The cusptron microwave tube concept is under development at NSWC as a compact high power device using the harmonic frequency generating scheme by an axis-rotating beam and a multivane circuit. Sixth and fourth harmonic frequencies have been independently generated with electronic efficiencies of approximately 10%. With this successful oscillator mode of operation, the cusptron is now being converted to an amplifier. The input and output couplers are one-turn loops located in different vanes. A TWT operating 4.0-8.0 GHz will be used as an RF driver. In this paper, we will present theoretical and experimental studies on the cusptron amplifier with a 30-50 keV, axis-rotating electron beam and a six-vane circuit.