RU178718U1 - SHF-GENERATOR ON MULTI-SPEED ELECTRON FLOWS - Google Patents

Abstract

The utility model relates to the field of microwave electronics and is designed to generate noise-like broadband signals of medium power. The technical problem is the creation of such a generator of noise-like broadband oscillations, which would ensure the receipt of signals in the high and ultra-high frequencies in the circuit without the use of external magnetic fields with a higher level of efficiency. The technical problem is solved by the fact that the microwave generator for multi-speed electron flows containing a sequentially located cathode, a modulating grid, the first and second anode in the form of grids with leads for connection to a power source and a piece of the electrodynamic system, made in the form of a spiral with energy output, according to the solution contains a drift pipe connected electrically to the second anode, with the possibility of providing a braking potential equal to the braking potential at the second anode U, the value of It lies in the range 0.5 * U ÷ 0.7 * U, where U is the potential of the first anode in the form of a grid. The diameter of the drift pipe is equal to its length. The radius of the drift tube is selected from the condition of ensuring the ratio of the radius of the electron flow from the cathode at the entrance to the drift tube to the radius of the drift tube is not more than 0.01.

Description

The utility model relates to the field of microwave electronics and is designed to generate noise-like broadband signals of medium power.

Chaotic signals are widely used in various fields of technology, such as information and telecommunication systems, radar, measuring equipment, etc. (see A.S. Dmitriev, A.I. Panas. M .: Fizmatlit. - 2002; NN Zalogin, VV Kislov. M: Radio engineering. - 2006.). In addition, it seems promising to use such signals in a number of manufacturing industries, such as oil refining, woodworking, etc. (see Yu.A. Kalinin, A.V. Starodubov, S.I. Berezin, Science and technology in industry. 3 (2009) 28-31.).

Vircators (VK) can be used to generate such signals. An example of such a device is a vircator containing a coaxial diode installed in the waveguide of a vacuum chamber and connected to an external power source, which is formed by a cylindrical cathode and anode, which is a cylinder-shaped grid connected to the waveguide by an anode electrode and a radiation output system. The anode is supplemented with at least one grid in the form of a cylinder, coaxial to the cathode, the grids have different diameters and are installed with the possibility of forming a virtual cathode between them (see RF patent for invention No. 2352014, IPC H01J25 / 00).

Known magnetically insulated vircator (see RF patent for the invention No. 2221306, IPC H01J25 / 74). The device consists of a cathode electrode and an anode electrode isolated from it, located in a magnetic field, the anode electrode comprising a sequentially installed modulating section in the form of a waveguide, covering the cathode electrode and the VC forming section, turning into a horn with a radiation output window, the waveguide of the VC forming section is made in the form of sections with a cross-sectional increase in the direction of radiation output, and these sections are separated in the plane of the jump by additional anode diameters apertures in the form of a grid transparent for the type of electromagnetic wave that is generated in the previous section of the waveguide.

Known microwave generator based on a virtual cathode with a radial beam (see RF patent for the invention No. 2395132, IPC H01J25 / 02). The device comprises a coaxial diode installed in a vacuum chamber and connected to an external power source, formed by a hollow cylindrical cathode and a hollow electron-transparent anode connected thereto, connected to the vacuum chamber body and transferred to a microwave output device. An axial electrode galvanically connected to the cathode is located in the cavity of the anode, while the cathode-anode pairs and the anode-axial electrode form coaxial lines with the same wave impedance, and are installed to provide artificial positive feedback. It should be noted that in the prototype, the difference between the wave impedances of coaxial lines and the absence of artificial positive feedback in the field of electron beam formation leads to a decrease in radiation power by 20 dB.

The above devices have a high output power, and increased efficiency, compared with earlier counterparts. However, their efficiency in this case still does not exceed 1-5%.

Closest to the claimed is a noise-like broadband microwave signal generator on a virtual cathode (see RF patent No. 2285819, IPC H01J25 / 68). The generator contains an electron source, an electrodynamic system with an energy output and a collector, one grid located between the electron source and the collector perpendicular to the direction of the electron beam with the possibility of forming a virtual cathode in the electrodynamic system between the grid and the collector. In this case, the electrodynamic system is made in the form of a segment of a spiral decelerating system, the energy output is made in the form of a waveguide transmission line, the electron source is made in the form of an electron gun, and the collector is in the form of an electrode located at the output of the generator.

However, to obtain chaotic signals, it is necessary to use large accelerating voltages (1-3 kV); the generator has a low efficiency value (1-2%) and significant overall dimensions.

The technical problem is the creation of such a generator of noise-like broadband oscillations, which would ensure the receipt of signals in the high and ultra-high frequencies in the circuit without the use of external magnetic fields.

The technical result achieved in the proposed device consists in increasing the efficiency and reducing the geometric dimensions and mass of the device.

The technical problem is solved by the fact that the microwave generator for multi-speed electron flows containing a sequentially located cathode, a modulating grid, the first and second anode in the form of grids with leads for connection to a power source and a segment of the electrodynamic system, made in the form of a spiral with energy output, according to the solution contains a drift pipe connected electrically with the second anode, with the possibility of providing a braking potential equal to the braking potential at the second anode U ₂ , the value which lies in the range 0.5 * U ₁ ÷ 0.7 * U ₁ , where U ₁ is the potential of the first anode in the form of a grid.

The diameter of the drift pipe is equal to its length.

The radius of the drift tube is selected from the condition of ensuring the ratio of the radius of the electron flow from the cathode at the entrance to the drift tube to the radius of the drift tube is not more than 0.01.

The utility model is illustrated by drawings.

Figure 1 presents a schematic diagram of a microwave generator for multi-speed electron flows.

In FIG. 2 shows the distribution of potential in the device.

In FIG. Figure 3 shows the results of numerical simulations of the dependence of the magnitude of the current on the walls of the drift pipe on the fill factor of the drift pipe's electronic flow.

In FIG. Figure 4 shows the results of numerical simulation of the dependence of the current density in the electron beam on the potential on the walls of the drift pipe for various values of the fill factor of the electron beam in the drift pipe.

The positions in the drawings indicate:

1 - cathode;

2 - modulating grid for the formation of a multi-speed electron beam;

3 - the first anode in the form of a grid with a terminal for connection to a power source;

4 - the second anode in the form of a grid with a terminal for connection to a power source;

5 - drift pipe of length L, diameter 2A;

6 - a segment of the electrodynamic system;

7 - broadband energy output;

8 - electron stream, the diameter of the electron stream in front of the first grid anode 2b;

9 is a view of the potential distribution of the first (U ₁ ) and second (U ₂ ) anodes;

10, 11 - obtained as a result of numerical simulation of the dependence of the current I / I ₁ values on the walls of the drift pipe;

12, 13 - obtained as a result of numerical simulation of the dependence of the maximum current density j / j _{0 of the} electron flux in the drift tube.

The microwave generator for multi-speed electron flows consists of a cathode 1 in series, a modulating grid 2, a first anode in the form of a grid with a terminal for connection to a power source 3 and a second anode in a grid with a terminal for connection to a power source 4. The second anode with a terminal for connecting to a power source 4 is electrically connected to the drift pipe 5 and is with it at the same potential. The diameter of the drift pipe 5 is equal to its length L. Behind the second anode 4, at the walls of the drift pipe 5, there is a segment of the electrodynamic system 6, made in the form of a spiral with a broadband energy output 7.

The microwave generator operates as follows.

Spherical-shaped electron streams 8 are emitted from the cathode 1. For the formation of multi-speed electron streams, speed modulation is performed by a modulating grid 2, which is connected to a DC power source to supply a potential higher than “natural”. After passing through the grid 2, the electron beam 8 is characterized by a significant spread of electrons in speed (up to 40-50%). This electron stream passes through the first anode in the form of a grid 3, connected to a constant current source and is under accelerating voltage (grid transparency not less than 90%). Next, the electron stream 8 passes through the second anode in the form of a grid 4, connected to a constant current source (grid transparency of at least 90%), which receives a potential less than the accelerating one, due to which part of the electron stream slows down. After that, the electron stream enters the drift tube 5, which is under the braking potential of the second anode in the form of a grid. Due to the supply of the inhibitory potential to the drift tube 5, the electrons propagating in the drift tube slow down significantly, turn around and propagate in the opposite direction. It is worth noting that the described different-velocity electron beam is easier to slow down and, moreover, deploy a significant part of the electron beam back to cathode 1. At this point, a region is formed in the drift space of the generator under study, in which there are counter-current electron streams formed by electron streams propagating from the cathode, and electron fluxes reaching the wall of the drift pipe opposite to the cathode and moving away from it after their turn towards the cathode. The described process occurs many times, which leads to the "closure" of the electron flow to itself and the formation of internal electronic feedback, which results in the appearance of undamped oscillations in the system. The useful signal in the generator circuit under study is removed using a segment of the electrodynamic system 6, made in the form of a spiral and output through the broadband output of energy 7. Since the walls of the drift pipe 5 are under the braking potential, this prevents the reflected electrons from deposited on the walls of the drift pipe. Consequently, the reflected electrons participate longer in the formation of clusters of space charge, thereby significantly increasing the current density in these clusters of space charge. An increase in the current density in clusters of space charge positively affects both the bandwidth of the generated microwave oscillations and their power.

As a result of numerical simulation (Fig. 3), dependences 9 are obtained — the type of potential distribution of the first (U ₁ ) and second (U ₂ ) anodes; and 10 - current values I / I ₁ on the walls of the drift pipe from the ratio of the radius of the pipe a of the drift and the radius of the electron beam b at the entrance to the pipe of the drift at U ₂ / U ₁ = 1; the current I ₁ corresponds to the current on the walls of the drift pipe at b / a = 0.5 and U ₂ / U ₁ = 1.

As a result of numerical simulation, a dependence of 11 current magnitudes I / I ₁ on the walls of the drift pipe on the ratio of the radius of the pipe a of the drift and the radius of the electron beam b at the entrance to the drift pipe at U ₂ / U ₁ = 0.7 was obtained; the current I ₁ corresponds to the current on the walls of the drift pipe at b / a = 0.5 and U ₂ / U ₁ = 1.

As a result of numerical simulation (Fig. 4), the dependence 12 of the maximum current density j / j _{0 of the} electron flux in the drift tube on the ratio of the accelerating potential and the potential on the walls of the drift tube obtained at b / a = 0.5 was obtained; where j ₀ is the current density of the electron beam at the entrance to the drift tube.

As a result of numerical simulation, a dependence of 13 of the maximum value of the current density j / j _{0 of the} electron flux in the drift tube on the ratio of the accelerating potential and the potential on the walls of the drift tube obtained at b / a = 0.01 was established; where j ₀ is the current density of the electron beam at the entrance to the drift tube.

The proposed circuit of the microwave generator can significantly reduce the current on the walls of the drift pipe formed by reflected electrons. The minimum electron deposition on the walls, and, consequently, a smaller current value in them, is achieved when the ratio of the electron beam radius b to the radius of the drift tube a does not exceed 0.01 (this dependence is indicated by 11 in Fig. 3) with a range of braking potential on the second anode U ₂ (and the drift pipe connected to it), equal to 0.5 * U ₁ ÷ 0.7 * U ₁ , where U ₁ is the braking potential at the first anode. In addition, numerical simulation also showed an increase in the maximum current density of the electron beam in the drift tube at the above parameters (this dependence is indicated by 13 in Fig. 4).

So, a feature of the inventive microwave generator is that it is possible to significantly reduce the deposition of reflected electrons on the walls of the drift pipe due to the low fill factor of the electron flow of the drift pipe, as well as by applying a braking potential to the walls of the drift pipe. In other words, in such a system, the current density in electron bunches increases significantly due to the absence of deposition of reflected electrons on the walls of the drift tube.

Thus, the proposed utility model makes it possible to increase the efficiency of a generator at multispeed electron flows due to an obstacle to the deposition of reflected electrons on the walls of the drift tube. Moreover, the claimed model is characterized by small geometric dimensions and mass due to the fact that there is no external focusing magnetic system.

Claims (3)

1. The microwave generator for multi-speed electron flows, containing a sequentially located cathode, a modulating grid, the first and second anode in the form of grids with leads for connection to a power source and a segment of the electrodynamic system, made in the form of a spiral with energy output, characterized in that it contains a drift pipe connected electrically to the second anode, with the possibility of providing a braking potential equal to the braking potential at the second anode U ₂ , the value of which lies in the range 0.5 * U ₁ ÷ 0.7 * U ₁ , where U ₁ is the potential of the first anode in the form of a grid. 2. The microwave generator according to claim 1, characterized in that the diameter of the drift pipe is equal to its length. 3. The microwave generator according to claim 1, characterized in that the radius of the drift pipe is selected from the condition of ensuring the ratio of the radius of the electron stream from the cathode at the entrance to the drift pipe to the radius of the drift pipe is not more than 0.01.

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