US2550759A

US2550759A - Amplifier of very high frequency

Info

Publication number: US2550759A
Application number: US749461A
Authority: US
Inventors: Bezy Georges
Original assignee: CSF Compagnie Generale de Telegraphie sans Fil SA
Current assignee: Thales SA
Priority date: 1940-12-26
Filing date: 1947-05-21
Publication date: 1951-05-01
Anticipated expiration: 1968-05-01
Also published as: CH224494A

Description

May 1, 1951 c. BEZY AMPLIFIER OF VERY HIGH FREQUENCY Filed May 21', 1947 INVEN TOR.

Patented May I, 1951 umrso Georges Bezy, Paris, France, assignor to Compagnie Generale do Telegraphic Sans Fil, a corporation of France Application May 21, 1947, Serial No. 749,461 In France December 26, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires December 26, 1960 11 Claims.

This invention relates to amplifiers for amplifying very high frequencies of the order of 1 metre or less.

Such an amplifier according to the invention comprises essentially an electronic beam projector, or an electron gun, a member for modulating the velocity of the electrons of the beam, a selection electrode for the electrons of the beam and a succession of electrodes of great output in secondary electrons, forming an electron multiplier.

Starting from the source of emission, the elec-- tron beam'is, after focalisation, first modulated in velocity and then a selection from among the electrons of difierent velocity is eiiected by the selection electrode, which eliminates from the beam certain groups of electrons according to their velocity. The beam, after traversing the selection electrode, is divided into bunches which, at the frequency of the source of velocity modulation, excite the electron multiplier.

The invention will now be further described with reference to the accompanying drawings, which illustrate by way of example one embodiment of the invention.

In Figure 1, F is a filament which heats a primary cathode C forming with control electrode G an ordinary electronic gun. This gun is capable of sending electrons into a chamber bounded by a circumferential wall and by two circular diaphragms D1 and D having each an orifice in the centre. In this chamber is an electrode, or drift space element, M of cylindrical form, concentric with the diaphragms D1, D2. Behind the diaphragm D2 is an electrode A1 of suitable shape, for example that of a spherical cap. This electrode also has an orifice in the centre. In the operation of the valve as an amplifier, the electrode A1 is inclined towards the axis.

A beam of electrons focalised by a G penetrates into the space D1, D2 and is accelerated by a somewhat high continuous current potential. If a difierence of high frequency potential, of suitable frequency with respect to the length of the cylinder M, exists between D1, D: on the one hand and the cylinder M on the other hand, the beam of electrons undergoes a modulation of velocity due to the accelerations in the gap existing between D1, D2 and the cylinder M. It is known that electrons can thus be accelerated twice or retarded twice.

The beam issuing from D2 is thus formed of electrons of difierent velocities which can be roughtly-classified into groups of rapid electrons and groups of slow. electrons, alternating with each other.

slow electrons. These electrons, directed oblique- 1y with respect to the axis, owing to the inclination of the electrode A1 or also to its shape (flat, convex, etc), are recuperated by the diaphragm D2 and their energy is lost in the form of heat. The diaphragm D2 forms thus an adsorption electrode.

The rapid electrons, on the contrary, are attracted by the electrode A1 and pass through the orifice in the centre thereof, falling on to an electrode C2.

The groups of electrons follow each other at a frequency corresponding to the frequency of the excitation potential and if C2 is capable of playing the part of a secondary cathode, by emitting several secondary electrons for one primary electron, fresh bunches of electrons of greater density can be accelerated towards Cg where the same phenomenon is reproduced.

The last amplified bunches reach the anode A and the current serves to develop energy at the terminals of an outlet circuit L2, C3.

The electrodes, in the form of rings B2, carried to a potential, for example near to that of the cathode, by means of a potentiometer device H, I, the cathode being on its part polarised by a similar device J, serve to maintain the beam focalised.

cessary.

The secondary cathodes C2 may be in the form of networks, grids or perforated plates. They are preferably bulged out an the side towards the primary cathode, in such a manner that there is a field between two cathodes which is oblique with respect to the axis.

The potentials of the diaphragms D1, Dz-and of the cylinder M are of the order of 1600 volts. The electrodes D1, D2 are excited. in high frequency by means of a resonator L1, C1 from a source 0 of oscillations. The potential of the electrode A1, of the order of +15 volts, is supplied for example, by a potentionmeter device S1. The potentials between A1, C2 and the different secondary cathodes are of the order of 360 to 400 volts and are supplied by a rectifying and filtering device V, S, R1, Re, Re, C10, C11, C12, C13, Cm.

The first of the secondary cathod-s may be constituted by the electrode A1 with retarding field, itself, the electrons having then to arrive These electrodes are not always ne- The secondary cathodes may also, according to a more ordinary form, be arranged as indicated by Figure 2, the focalisation for the multiplication being then electrostatic.

The secondary cathodes may be at distance such, that the duration of travel of the electrons between two cathodes is equal to half a period. Under these conditions, there would always be a secondary cathode between two groups of electrons, which will not be in operation and which will serve as a screen.

The invention is susceptible to considerable variation as regards constructional details, for example as regards the method of mounting the constitutent elements and all such variations are to be understood as within the scope of the invention.

What I claim is:

1. An amplifier device for very high frequencies, comprising in combination a device for projecting an electronic beam, means under control of an input circuit for modulating the velocity of the electrons of the beam and bunching them in phase with said input, means including an electrode positioned relatively to the bunched electrons for selecting the electrons by bunches according to their velocity, a electron multiplied system positioned to receive the high velocity bunches of electrons, and means to supply the output energy of the multiplier to an outlet circuit.

2. A device according to claim 1, in which there is included an absorption electrode and in which the means for selecting the highest velocity bunches of electrons in the beam comprises an electrode provided with means for directing the slower velocity bunches toward said absorption electrode and the highest velocity bunches toward the multiplier system.

3. A device according to claim 1, in which there is included an absorption electrode and the means for selecting the highest velocity bunches of electrons comprises an electrode provided with means for directing the low velocity bunches toward said absorption electrode, and in which said electrode constitutes a cathode of the multiplier system cnergized by the high velocity bunches.

4. A device according to claim 1, in which the multiplier system comprises a plurality of secondary emissive cathodes which successively refiect the incident beam toward the following cathode.

5. A device according to claim 1, in which the multiplier system comprises a plurality of secondary emissive cathodes arranged at such disstances apart that the transit time of electrons between two successive cathodes is equal to a half-period of the amplified oscillation.

6. An amplifier device for very high frequency, comprising a generator of an electron beam, a first gap traversed by the beam and associated therewith, means for modulating the velocity of the electrons in accordance with the frequency of the input energy of the amplifier, a, drift space element communicating at one end with said first gap and having a length such that the velocity modulated electrons are grouped in bunches at the other end of said drift space element, a second gap communicating with said other end and traversed by the bunches of electrons issuing from said drift space element, means positioned with respect to said second gap for acting on the velocities of the bunches phased with the modulating means acting on said first gap, a secondary electron multiplier system, means for' exciting said system solely by the selected bunches of highest velocity electrons in the beam, and means for receiving the output amplified frequency in the outputting circuit of said multiplier system.

7. A device according to claim 6, in which the means for selecting the bunches of highest velocity electrons comprises an electrode biassed at a potential negative respecting the electrodes of the second gap as influenced by the alternatin field, said electrode being inclined to the axis of the beam and having an opening for the passing of the high velocity bunches toward the multiplier system.

8. A device according to claim 6, in which the means for selecting the bunches of highest velocity electrons comprises an electrode biassed to a potential negative respecting the electrodes of the second gap as influenced by the alternating field, said electrode havin the form of a spherical segment and inclined to the axis of the beam and having an opening for passage of the high velocity bunches toward the multiplier systom.

9. A device according to claim 6, in which the means for modulating the velocity of the electrons in the first gap and the means acting in phase with the modulated velocities in the second gap comprises an input electrode of the first gap and an outlet electrode of a second gap biassed at the same accelerating potential, and including means for applying the input frequency between one of said two electrodes and the drift electrode.

10. An amplifier device for very high frequencies, comprising in combination, a device for projecting an electronic beam, means under the control of an input circuit for modulating the velocity of the electrons of the beam and bunching them in phase with said input, means including an electrode positioned relatively to the bunched electrons for selecting the electrons by bunches according to their velocity, an electron multiplier system positioned to receive the high velocity bunches of electrons and comprising a plurality of secondary emissive cathodes presenting convexity toward the incoming beam, and means to supply the output ener y of the multiplier to an outlet circuit.

11. An amplifier device for very high frequencies, comprising in combination a device for projecting an electronic beam, means under control of an input circuit for modulating the velocity of electrons of the beam and bunching them in phase with said input, means including an electrode positioned relatively to the bunched electrons for selecting the'electrons by bunches according to their velocity, an electron multiplier system positioned to receive the high velocity bunches of electrons and comprising a plurality of secondary emissive cathodes, a ring between each pair of said cathodes, means for biassing said ring at a potential approximately that of the primary electronic beam source, and means to supply the output energy of the multiplier to an outlet circuit.

' GEORGES BEZY.

.EEFERENCES CETED The following references are of record in the file of this patent:

UNITED STATES PATENTS