Phase-locked Gyrotron Oscillator Research Articles

Quasilinear theory of mode interaction in gyrotrons with azimuthally inhomogeneous electron emission

A theory is developed which describes the effect of the azimuthal inhomogeneity of the electron current on the gyrotron operation. The theory is simplified by using a quasilinear approach, which allows one to study analytically the stability of oscillations in free-running and phase-locked gyrotron oscillators with inhomogeneous current emission. Also the numerical analysis of nonstationary processes in a three-mode gyrotron oscillator is carried out. The results show that, at low currents, the inhomogeneity may cause excitation of additional modes at the frequency of the operating one. At higher currents, one can observe the onset of phase-locked triplets with equidistant frequency spectrum. As the inhomogeneity increases, this enhances the beating effects in such triplets, e.g., the mode amplitudes exhibit some oscillations whose period is inversely proportional to their frequency separation and whose modulation increases with the inhomogeneity in the beam current.

Review of the theory of mode interaction in gyrodevices

The present paper contains a brief overview of the studies of mode and wave interaction in gyrodevices. The main part of it is devoted to the discussion of physical effects caused by mode interaction in the free-running and phase-locked gyrotron oscillators. Also, the problem of the stability of large-signal operation of gyro-forward-wave amplifiers with respect to excitation of parasitic backward waves is discussed.

Technical noise in gyroklystrons and phase-locked gyrotron oscillators

The formalism describing the effect of fluctuations in the technical parameters and in the driving signal on the radiation linewidth in gyroklystrons and phase locked gyrotron oscillators is developed. The phase locking by direct injection of the input signal into the resonator and by prebunching of electrons in the input cavity followed by the drift section is considered. In the first case the results of analysis of the free running gyrotron oscillator given in a companion paper [Phys. Plasmas 4, 1413 (1997)] can be used in a straightforward manner. For gyroklystrons and phase-locked gyrotron oscillators with prebunched electron beams, the numerical study is carried out. In particular, the effect of the detuning of the signal frequency from the eigenfrequency of the resonator on the linewidth of radiation in a gyrodevice with a given level of technical noise is analyzed.

Experimental proof-of-principle results on a mode-selective input coupler for gyrotron applications

Proof-of-principle results for a mode selective input coupler are presented. Transmission and reflection measurements for the TE/sub 02/ cylindrical waveguide mode are given along with the output mode pattern. The results show good agreement for the cutoff frequency, mode pattern general behavior and variation with frequency for signals above cutoff. A maximum passband of 1.2 GHz (/spl sim/7%) has been achieved. Comparisons with theory for overall frequency response (from 15 to 18 GHz) and mode pattern characteristics (at 17.5 GHz) are also presented. The design and concept are promising for harmonic gyrotron-traveling-wave-tube amplifier and phase-locked gyrotron oscillator applications.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of a high voltage multi-cavity 35 GHz phase-locked gyrotron oscillator

This paper describes the design for an experimental high power, phase-locked gyrotron oscillator. The electron beam is generated by a 1 MV pulseline accelerator, and the reference signal is provided by a 35 GHz, 20 kW magnetron. The expected output power is in the range 1 to 10 MW. The design is based on a solid 1 MeV, 100 Amp, 4 mm electron beam with a momentum pitch ratio ∞ of 0 · 75. The locking signal from the magnetron is introduced via a prebunching cavity. A second (passive) bunching cavity is used to increase the locking frequency bandwidth obtainable with a given locking power. The bunching cavities are designed to operate in the fundamental TE111 cylindrical cavity mode. Some competition from the TE112 higher order axial mode could not be avoided owing to the constraint on the minimum drift tube diameter set by the requirement to propagate the electron beam. The bunching cavities include two axial slots to control the cavity Q factor and suppress competing modes. Additional slots and apertures a...

Theory of the multi-cavity phase locked gyrotron oscillator

ABSTRACT A perturbation theory is developed for investigation of the two cavity phase locked oscillator. In this theory, the unperturbed state is the free running oscillator. The prebunching current then slightly perturbs the frequency and field profile, and one can calculate the condition for phase lock. The theory is analytically tractable, and as in the analogous case of the gyroklystron amplifier, the dimensionality of the parameter space is greatly reduced.