Design of a large orbit gyrotron with a permanent magnet system

Abstract

In this paper, we present results of a conceptual design study of a prospective gyro-device with a permanent magnet system and an axis-encircling electron beam. Computer-aided electron-optical design of the tube has been performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic physical model and is developed as a problem-oriented tool for analysis of electron-optical systems with conventional magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. Results of numerical experiments predict satisfactory performance of the gun which is expected to form high-quality axis-encircling electron beams with small ripple and dispersion of the velocities. Parameters of the beams (current, radius, velocity ratio, etc.) are appropriate for weakly relativistic harmonic large orbit gyrotron (LOG). The cavity was optimized for excitation of TE 41 mode at the fourth harmonic of the cyclotron frequency. The results of this feasibility study will be used as a basis for development of a novel LOG with a permanent magnet system. The target parameters of such a prospective device are frequency of generated microwave radiation about 104 GHz, output power near 1 kW and efficiency of several percent.