Victor D. Yeryomka

Optimal conditions for drift-orbital resonance in M-type devices

The large-orbit and small-orbit regimes of an M-type oscillator in the drift-orbital resonance mode are considered. The theoretical analysis of oscillator characteristics is performed for each regime. The comparison between experimental and theoretical data is made. Conclusions concerning the electron-wave interaction mechanism in millimeter-band magnetrons are presented.

Large-orbit M-type oscillator with the adiabatic electron-optical system

The large-orbit M-type oscillator with the adiabatic electron-optical system in the specific drift-orbital resonance mode is considered. A theoretical analysis of electron trajectories is made. According to early estimates, this system is free from shortcomings typical for a gyrotron and a peniotron when an operating wavelength becomes shortened to a millimeter and submillimeter band.

Investigation of Millimeter-Wavelength 20-Vane Spatial-Harmonic Magnetron Using Three-Dimensional Particle-in-Cell Simulation

We investigate, using the 3-D particle-in-cell simulation code MAGIC, the millimeter-wavelength 20-vane magnetron operating at one of the spatial nonfundamental harmonics of the backward-traveling wave. This spatial harmonic is characterized by 16 (p = 16) RF electric field variations along the circumference of the magnetron interaction space (oscillation region). We call this magnetron as the “spatial-harmonic” magnetron operating in the “spatial-harmonic mode.” Calculated electron distribution reveals 16 electron spokes in the interaction space, which confirms the spatial-harmonic mode of the magnetron operation at p = 16. We observe a saturated output power of 3.2 kW, which corresponds to a power conversion efficiency of 12.3% when the applied voltage is 6.5 kV and the external magnetic field is 0.4 T. The operating frequency is 35.2 GHz. The collected anode current is 4 A when the current emitted from the cathode is 6.3 A. The dissipated power at each anode vane, depending on the anode vane position, is varied by the factor 1.8. The energy of back-bombarding electrons on the cathode increases from 305 to 503 eV while the spatial-harmonic magnetron operation is stabilized.

3-D Simulation of Millimeter-Wave Cold Secondary-Emission Cathode Drift-Orbital Resonance Magnetrons

The mathematical 2-D model describing in a self-consistent fashion the physical processes in millimeter-wave (MMW) cold second-emission cathode (SEC) magnetrons operating on a space harmonics of non- pi - mode oscillation can be used to study both the dynamics of establishing self-induced oscillations and the stationary oscillations regimes (Sosnitskiy and Varviv, 2002). However the 2-D model does not take into account the finiteness of its space interaction axial length in these magnetrons. A 3-D mathematical model for the cold SEC magnetrons has been worked out allowing for the finiteness of the axial length of its space interaction (Kopot, 2005). The numerical experiment involves the use of the PIC code. The equations presented in (Vaughn, 1993) have been taken into consideration in simulating the secondary electron emission processes with regard to the angle at incidence of primary electrons. The input data for the numerical experiment are the parameters that can be measured: geometry of magnetrons space interaction, natural frequency and the loaded Q of the oscillatory circuit on an operating mode, a permanent magnetic field and an anode voltage. The device output performances such as anode current, output power and efficiency are the results from calculations and do not require that their rough value are known. Simulations are made of dynamic processes of secondary electron multiplication and the device output in stationary mode

Coaxial cold-cathode magnetron

We have studied the experimental prototype of an X-band pulsed coaxial magnetron (CM): /spl tau/ = 70 ns; F = 1000/spl tau//s. The above magnetron uses a metalporous secondary-emission cathode (SEC) as a set of rings between the discs made of refractory metal are placed, with the blade-like shoulders being periodically arranged around their edges. For tunneling the required excitation current from the field emitter (FE) the value of the electric field strength (E/sub ef/) should be around 10/sup 7/ V/cm . But at an anode voltage of 5 to 10 kV, E/sub ef/ is two orders of magnitude less than is required. The normal operation of the magnetron prototype is based on 1) the results from the theoretical and experimental studies into the configuration of field emitters; 2) the selection of their material ensuring an increase in E/sub ef/ on the top of blade-like shoulders up to /spl sim/10/sup 7/ V/cm and 3) FE activation using the active SEC substance. In the course of experiments one could observe reliable generation of stable oscillations in a short-pulse mode of the operating CMs. For an 8 kV anode voltage the CM output pulse power of over 10 kW at 25% efficiency is provided.

THz-Range Spatial-Harmonic Magnetrons

The numerical simulation has been used to determine the tentative parameters submm- wavelength SHMs. The reliability of the developed 3-D models is evidenced by the results from testing of the operating laboratory prototypes of the THz-range thermionic-cathode SHMs. The 3-D model thus created can be used in developing the small-size THz-range cold secondary-emission SHMs. The concept of drift-orbital resonance in SHMs allows testing the basic parameters of THz-range magnetrons. It can be used to develop the submm-wavelength spatial-harmonic magnetrons. It can be used to develop the submm-wavelength spatial-harmonics magnetrons.

The flow forming potential in unconventional magnetrons

Unconventional magnetrons are widely used in the millimeter-wave band. Their operating magnetic fields are 3-4 times lower than that of conventional devices. The geometrical dimensions of an interaction space are greater than for conventional ones with the same wavelength. At the present time, the physical and mathematical model of an electron-wave interaction, explaining the essential difference of such magnetrons from conventional devices, is not yet developed. In this paper, an attempt is made to analyze the processes in the millimeter-wave low-field and space harmonics magnetrons, on the basis of parameters uniting all these tubes.

Frequency Multipliers with Inclined Electron Flow

A great interest has been shown in using terahertz range. Considered in this paper are the possibilities of using frequency multiplication principles in designing vacuum electromagnetic radiation sources featured by inclined electron flow in the short-wave bands including terahertz band. Presented here are the results of simulation and experimental studies of millimeter-wave frequency multipliers, particularly, multiplier klynotrons, multiplier orotrons and multiplier orbotrons with increased frequency multiplier factors kf =15. Electro-dynamic system of these devices is a power take-off cascade. It is shown that power take-off cascade can operate within the frequency band which exceeds an octave with frequency conversion factor over 10. Energy and frequency characteristics of the frequency multiplier are given.

Multicavity Magnetrons with Cold Secondary Emission Cathode: Achievements, Problems, Perspectives

This paper presents the review of investigations of multicavity magnetrons with cold secondary-emission cathode operating over the mm-wave band, side-cathode magnetrons and X-band coaxial magnetrons designed and developed at the A. Ya. Usikov IRE NASU for the period 1955 through 2005 and at Radioastronomical Institute (Rl NASU) for the period 1985 through 2005. The distinctive features of magnetrons design, their operating modes, and energy characteristics are presented. Parameters of magnetron design are given. The results of theoretical and experimental study and applications of cold-cathode magnetrons are briefly described. It is shown that using cold secondary-emission allows extending service life of mm and submm-wave magnetrons, improving energy characteristics, and increasing functional capabilities. It is shown that over 35-150 GHz frequency band magnetron oscillators operating on higher space harmonics of non-pi-mode oscillations have the parameters that satisfy practical requirements

Millimeter- and submillimeter-wave amplifiers on sheet-beam orboklystron

Simulation of mm-and submm-wave amplifiers is performed. A mathematical model is formulated with regard to both the space charge of sheet beams and field sagging in gaps. The power gain of orbictro-klystron (orboklystron) amplifiers is shown to be as high as 20-30 dB at frequencies of 100 to 200 GHz.