Galina I. Kalynova

Method for Synthesis of Waveguide Mode Converters

We propose an iterative method for synthesis of waveguide mode converters. An application of this method for bent circular waveguides is considered. Examples of synthesized converters calculated using this method are presented. The method offers fundamentally new solutions to the problems of mode converter development.

CW Ka-Band Kilowatt-Level Helical-Waveguide Gyro-TWT

Experimental results and design details are presented on an amplifier setup based on a helical-waveguide gyrotron traveling-wave tube delivering continuous-wave kilowatt-level output power with an instantaneous frequency bandwidth of about 3%.

Microwave source based on the 24 GHz 3 kW gyrotron with permanent magnet

A 24 GHz 3 kW CW gyrotron (n=2) with permanent magnet and microwave source based on the gyrotron are developed. The source incorporating a set of power supplies, transmission line, and PC-based RF power control extends a line of gyrotron systems designed as a versatile and user friendly tool for research in microwave energy applications.

Frequency Tuning in a Subterahertz Gyrotron With a Variable Cavity

According to calculations, electromechanical frequency tuning by 8% relative to a central frequency of 316 GHz can be provided in a high-power gyrotron with a slit and variable cavity. A monoaxis helical electron beam (configuration of large orbit gyrotron) is proposed for the use in such an oscillator instead of the conventional polyaxis beam, which was used in earlier long-wavelength prototypes. This modification increases gyrotron efficiency and frequency tuning range, as well as stability of the generation regime. A mechanism for the precise parallel movement of the cavity halves and mode converter, which transforms an azimuthally standing cavity mode into a wavebeam, have been designed. Peculiarities of frequency tuning associated with the coupling of the operating and parasitic modes in the slit cavity have been studied.

Development of helical-waveguide gyro-TWT and gyro-BWO

New projects and experimental results on low-relativistic second-harmonic gyro-devices using a microwave system in the form of a helically corrugated waveguide will be presented. A CW 30 kV/0.7 A gyro-TWT with designed output power up to 4 kW and frequency bandwidth 29.8–31.3 GHz (5%) will be discussed in more detail.

New results in development of MW output power gyrotrons for fusion systems

Gyrotrons are widely used in electron-cyclotron-wave systems of fusion installations. Modern and future installations require microwave sources with power at least 1 MW. CVD diamond windows are implemented into the gyrotrons with frequencies 140 GHz and 170 GHz. The goal of these near-time tests is to demonstrate 0.8-1 MW power in microwave pulse of 10 seconds at least at two frequencies 105 GHz and 140 GHz, corresponding to pass bands of the single diamond disc.

Synthesized quasi-optical TE02-HE11 mode converter

We consider a compact quasi-optical mode converter for technological gyrotrons operating at low-order modes of cylindrical resonators. The converter was calculated, fabricated and measured at low and high power. Simulations and experiment confirmed a possibility to achieve rather high efficiency of quasi-optical converters for low-order modes.

24-28 GHz Gyrotron-based Sources for Technological Applications

A design of gyrotron-based systems and examples of their applications are presented. The field of application of the millimeter-wave (mm-wave) energy extends considerably in the last years. Several models of the 24 -28 GHz gyrotron-based systems ranging from 3 to 15 kW in continuous wave power have been recently developed by the Institute of Applied Physics. The design of these systems is presented. Examples of their use for materials processing, production of ion beams, and mm-wave plasma assisted chemical vapor deposition are given.

MEASUREMENT OF NEAR-MEGAWATT MILLIMETER-WAVE BEAMS

To measure parameters of microwave beams produced by modern gyrotrons, a number of special devices have been developed: quasi-optical filters, bi- directional couplers, calorimetric loads, etc. The wave beam pattern is studied by measuring intensity distributions at several cross-sections, which is used to reconstruct the beam phase distribution and design proper matching mirrors.

Development of gyrotron-based technological systems at Gycom/IAP

The line of gyro-device systems produced jointly by Gycom and IAP for millimetre-wave processing of materials has been extended by two new setups. The general description and major technical specifications of a 5 kW 24.1 GHz gyrotron-based system and a dual-frequency system exploiting a 15 kW 28 GHz gyrotron and a 2.5 kW 24.1 GHz gyro-backward-wave oscillator (BWO) frequency tuneable in the range of /spl plusmn/0.5 GHz are presented.