RU2514850C1 - Travelling-wave tube - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention relates to microwave engineering. Travelling-wave tubes, which are based on the principle of continuous prolonged interaction of an electron stream with the field of a travelling electromagnetic wave in a non-resonant oscillatory system, can be used in different electronic equipment. The travelling-wave tube has an electron gun, a retarding system consisting of a chain of connected resonators, input and output waveguides with dielectric sealing partitions which separate the vacuum retarding system from non-vacuum microwave channels, a focusing system in form of electrical or permanent magnets and a collector. The retarding system is divided into multiple sections in which there are no absorbing devices and which are connected to each other though waveguide sections in which there are decoupling devices, which enable microwave power to pass in the forward direction and not in the reverse direction.

EFFECT: high gain of the tube and simple device.

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Description

FIELD OF THE INVENTION

The invention relates to the field of microwave technology. Lamps of a traveling wave, based on the principle of continuous long-term interaction of the electron beam with the field of a traveling electromagnetic wave in a non-resonant oscillatory system, can be used in various electronic equipment.

State of the art

The development of multi-purpose radar for long-range tropospheric and space communications of modern means of radio-electronic suppression (REP) of information channels of weapon control systems requires the creation of broadband amplifiers of high-frequency microwave oscillations of more than 100 watts.

The most promising electrovacuum devices that make it possible to create such amplifiers are O-type traveling-wave lamps with longitudinal electric and magnetic fields. Due to the interaction of the electron beam distributed over the length with the electromagnetic field of the traveling wave in devices of this type, significant gain is achieved with a relatively small beam current. Gain factors, if necessary, can reach 60 dB or more. The use of slow-wave systems with weakly pronounced resonant properties provides amplification in a wide frequency band reaching two or more octaves. Powerful TWT continuous and pulsed modes are among the fastest growing group of microwave devices. A wide band of amplified frequencies is most easily achieved by using spiral decelerating systems. In the transition to average powers of the order of kilowatts or more, one has to switch to resonator moderating systems, which when used in TWT always give a smaller band of amplified frequencies (usually not more than 10%). In modern powerful TWTs, the most commonly used slowing systems are in the form of chains of resonators with inductive coupling made in the form of a diaphragmed circular waveguide. Neighboring resonators are interconnected through slots cut in the diaphragms. To obtain the limiting parameters in terms of power and efficiency, amplification chains consisting of a preamplifier (TWT) with a large gain and an output “transparent” TWT without absorbers with a small gain (7-15 dB) were also widely used. In a “transparent” TWT, resonator slowdown systems are also most often used.

A powerful TWT usually contains a retardation system in the form of a chain of coupled resonators with inductive coupling. The electron stream is created by an electron gun. In a retarding system, the kinetic energy of electrons is converted to microwave energy. After passing through a slowing system, the "spent" electronic stream enters the collector. The first and last resonators of the retardation system are used to input the amplified microwave signal and output the amplified signal, respectively, and are connected with waveguide microwave paths. Sealing dielectric partitions separate the evacuated retardation system from the non-evacuated microwave paths. The magnetic field focusing the electron beam is created by a magnetic system consisting of a series of electric or permanent magnets.

For TWTs with a retardation system in the form of a chain of coupled resonators, the problem of matching the latter with transmission lines is one of the most urgent. It is extremely difficult to get good retardation between the transmission system and the transmission lines in the entire working band. Therefore, there is a risk of internal feedback due to the reflection of the electromagnetic wave at the ends of the slow-wave system, especially at the borders of the passband. At the same time, TWT can stop fulfilling its functions and become self-excited. To eliminate self-excitation, either selective absorbers (for example, from ceramics of the KT-30, AN-35Zh, PMK, AN-MKH brands) are placed in the retardation system, which introduce losses in limited regions of the passband of the retardation system (near the strip boundaries), or distributed film absorbers (e.g. alsifer film). TWT becomes divided into separate sections. Moreover, the characteristics of the sections can be varied, increasing, for example, the output power or leveling the amplitude-frequency characteristic of the TWT.

Sectioned TWTs in which slowing down systems consist of chains of coupled resonators are described in the book by Katsman Yu.A. "Microwave devices. Theory, fundamentals of calculation and design of electronic devices": Textbook for universities on special. "Electronic devices". - 2nd ed., Revised. and add. - M .: Higher. Shk., 1983.- 368 p. and in patents No. 2235384, 2290714, 2297687, 2313154, 2394303.

The powerful TWT described in the book by Katsman Yu.A. can be considered as a prototype. It contains an electron gun, a retardation system consisting of a chain of coupled resonators, sealing dielectric partitions separating the evacuated retardation system from the non-vacuum microwave paths, a focusing system in the form of a solenoid, and a collector cooled by water. The input resonator of the retarding system with screws for adjusting the matching and the output resonator with the matching diaphragm form the so-called matching devices. Absorbers with matching rings are installed in the middle part of the retarding system. In such a device, a gain of several tens of dB can be obtained. The use of absorbers significantly complicates the construction of TWTs and limits their working bands to units of percent, and in the millimeter wavelength range their use is practically not feasible.

The gain of the “transparent” single-section TWTs does not exceed 15 dB and they are usually used as an output amplifier in amplification chains. The use of several sections in the TWT without absorbers similar to a “transparent” TWT, each of which is “connected” by the beam and by the microwave power (the waveguide output of the first section is connected to the input of the second section, etc.) will make it possible to obtain a TWT gain of several tens of dB, while retaining all the advantages of "transparent" TWT. To eliminate TWT excitation between sections, it is necessary to install decoupling devices, for example, ferrite valves or circulators.

SUMMARY OF THE INVENTION

An urgent problem is the creation of powerful broadband TWTs with a gain of about 40-50 dB without the use of absorbers.

The indicated problem is solved as follows. A powerful TWT contains an electron gun that slows down the system in the form of a chain of coupled resonators, divided by partitions into separate sections without absorbers, which are interconnected by segments of waveguides, a magnetic system, and a collector. The electron stream is created by an electron gun. Passing through the retardation system, the beam is inhibited in each section and transfers part of the energy to the electromagnetic field. The output resonator of each section is connected to the input resonator of the subsequent section using a section of the waveguide. To eliminate the influence of the sections on each other, a decoupling device, for example, a ferrite valve or a circulator, is included in the waveguide. This device allows microwave power to pass in the forward direction and does not allow in the opposite direction. Unused portion of the beam enters the collector. The input waveguide of the first section and the output waveguide of the last section, connected to the slowdown system through a slit and separated from the microwave paths by sealing dielectric partitions, serve to input the amplified microwave signal and output the amplified signal, respectively. The sections of the waveguide between the sections are also connected to the decelerating system through the slots and serve to transmit the amplified microwave signal of the previous section to each subsequent section, starting from the second. The magnetic field that focuses the electron beam is created by a magnetic system consisting of a series of electric or permanent magnets. Significantly simplified is also the task of obtaining good coordination (standing wave coefficient KSVn≤1.5) in the working band of the retarding system, which can significantly exceed 10%.

List of drawings

Figure 1. A traveling wave lamp, consisting of several sections in which absorbers are not used, and the sections are interconnected by waveguide segments.

Information confirming the possibility of carrying out the invention

The traveling wave lamp shown in FIG. 1 contains the following devices:

- electronic gun 1;

- a retarding system in the form of a chain of coupled resonators 2;

- magnetic system 3;

- collector 4;

- input waveguide 5;

- output waveguide 6;

- isolation device 7;

- input sealing dielectric partition 8;

- output sealing dielectric partition 9.

The electron flux generated by the electron gun (pos. 1) propagates along a slowing down system consisting of several sections (pos. 2) and interacts with the longitudinal component of the electric field of the amplified microwave wave, as well as with the longitudinal focusing magnetic field created by electric or permanent magnets (item 3). An electron beam in the process of interaction with a microwave wave is modulated in speed, which leads to modulation of the flux in density. Due to the mutual relationship between the microwave field and the electron beam during its movement from the input of the slowing system to the output, this process is enhanced, and the kinetic energy of the electrons is transferred to the field when they are braked. As a result, the input microwave signal is amplified supplied from the input segment of the waveguide (item 5). The power at the output of the first section through the segments of the waveguide and the decoupling device (pos. 7) is transmitted to the second section, from the second section is transmitted to the next, etc. The microwave amplified signal is output through the output waveguide (item 6). The "spent" electron stream enters the collector-recuperator (item 4), where unused kinetic energy is partially "returned" to the high voltage source due to its recovery, and partially goes into thermal energy.

The presence of the connection of the sections of the device by microwave signal reduces the length of the device or increases the output power compared to the prototype due to the fact that the second and next sections include an already modulated beam. In addition, it simplifies the ability to equalize the amplitude-frequency characteristics of the device, because the beam does not experience misphasing at the beginning of the second and subsequent sections during the buildup of the microwave signal from the zero level, as is the case in a multi-section prototype lamp with isolation by microwave power in the form of absorbing devices.

Claims (1)

 A traveling wave lamp containing an electron gun, a slowing down system consisting of a chain of coupled resonators, input and output waveguide microwave paths with dielectric sealing baffles separating a vacuum slowdown system from non-vacuum microwave paths, a focusing system in the form of electric or permanent magnets and a collector, characterized in that the slow-down system is divided into several sections in which there are no absorbing devices and which are interconnected by a microwave signal through ki waveguides disposed therein decoupling devices.