Oscillators – Beam tube
Patent
1990-10-17
1992-05-12
Grimm, Siegfried H.
Oscillators
Beam tube
315 39, 331 81, 331 86, H01J 2574, H03B 901
Patent
active
051131544
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The object of the present invention is a microwave generator device using the virtual cathode phenomenon.
DISCUSSION OF BACKGROUND
A known way of generating microwaves consists notably in the use of devices called vircators which make advantageous use of the space charge effects in electron beams produced by the gun of an electron tube. Indeed, as is known, it is these effects that, for given voltages, fix a maximum value for the current that may be produced by an electron gun, or again may be carried in a given space for a set of electrodes with a given geometry. In a vircator, there is injected, into a defined space, a stream of electrons most often equal to several times the maximum current that could effectively cross this space. There is then an accumulation of electrons which form a potential well, called a virtual cathode, and this accumulation prompts the reflection of a variably large fraction of the electrons of the beam. This virtual cathode is unstable, that is, the amplitude of its potential well and its position oscillate, leading to a periodic variation in the number of reflected or transmitted electrons. A device such as this enables the creation of electromagnetic fields with high microwave power values and in a restricted volume. However, it is observed that the power is emitted in several modes in a sequence of simultaneous or successive frequencies. The applications of signals of this type are thereby quite restricted. Besides, the conversion efficiency is poor (of the order of 2% to 3% at most) as compared with the efficiency that can be obtained with other generators, such as standard velocity modulated electron tubes.
SUMMARY OF THE INVENTION
An object of the present invention is a microwave generator that uses the oscillating virtual cathode phenomenon but makes it possible to obtain microwave energy of better spectral quality and with higher conversion efficiency than with standard vircators.
This is achieved by the separate use of the electrons of a given phase (i.e. transmitted electrons or reflected electrons) to convert their kinetic energy into microwave energy.
More precisely, the object of the invention is a microwave generator device comprising:
a electron gun, capable of producing an electron beam in a region of injection, the current carried being sufficient to prompt the formation of a virtual cathode;
an output microwave circuit, performing the conversion of the kinetic energy of the electrons into a microwave energy, such that the energy of the electrons that it picks up is in phase, either in using solely the energy of the transmitted electrons or in using solely the energy of the electrons reflected by the virtual cathode, or again in using both the energy of the transmitted electrons and that of the reflected electrons, but with this energy being suitably phase-shifted.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, particular features and results of the invention will emerge from the following description, given as an non-restrictive example and illustrated by the appended figures, of which:
FIG. 1 shows a first embodiment of the generator device according to the invention, wherein the output microwave circuit uses the electrons transmitted by the virtual cathode;
FIG. 2 shows a second embodiment of the device according to the invention, wherein the output microwave circuit further provides for a post-acceleration of the electrons used;
FIG. 3 shows another embodiment of the device according to the invention, wherein the output microwave circuit uses, firstly, the electrons transmitted by the virtual cathode and, secondly, the electrons reflected by this virtual cathode but suitably phase-shifted.
FIG. 4 shows another embodiment wherein the produced beam is a solid cylinder;
FIG. 5 is another solid cylinder embodiment having post-acceleration means; and
FIG. 6 is yet another full cylinder electron beam corresponding to utilization of both transmitted and reflected electrons from the virtual cathode.
In these different figures
REFERENCES:
patent: 3084293 (1963-04-01), Munushian et al.
patent: 4150340 (1979-04-01), Kspetanakos et al.
patent: 4345220 (1982-08-01), Sullivan
patent: 4730170 (1988-03-01), Kwan et al.
1983 IEEE International Conference on Plasma Science, 23-25 May 1983, San Diego, Calif., IEEE Conference Record-Abstracts, IEEE (New York, U.S.), T. J. T. Kwan et al.: "Microwave generation by virtual cathodes and reflexing systems", p. 40, resume 2D6.
Journal of Applied Physics, vol. 32, No. 12, Dec. 1961, "Space-Charge Instabilities in Electron Diodes and Plasma Converters", C. K. Birdsall et al., pp. 2611.sub.]2618.
Journal of Applied Physics, vol. 34, No. 10, pp. 2946-2955, Oct. 1963, "Space-Charge Instabilities in Electron Diodes", William B. Bridges et al.
SPIE vol. 873 Microwave and Particle Beam Sources and Propagation (1988), pp. 92-103, "Relativistic klystron amplifier", M. Friedman et al.
Brasile Jean-Pierre
Convert Guy
"Thomson-CSF"
Grimm Siegfried H.
LandOfFree
Microwave generator device with virtual cathode does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microwave generator device with virtual cathode, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microwave generator device with virtual cathode will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2426933