JPS6226545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave electron tube that utilizes cyclotron motion of electrons to allow electrons and electromagnetic waves to interact, thereby having an oscillation or amplification function.

The electron beam emitted from the electron gun can be formed into a group of electrons with cyclotron motion through the focusing process by an external magnetic field. As such an electron gun, an adiabatic magnetron incidence electron gun is used. In this electron gun, electrons emitted from the emitter surface in a weak cathode magnetic field are accelerated by the electric field component perpendicular to the magnetic flux, and have the energy of a swirling motion with a cyclotron frequency. Then, when electrons are extracted into a magnetic field that gradually increases in the axial direction, the ratio of the energy of the swirling motion to the energy of the axial motion increases as the magnetic field increases, and the motion of the electrons is adiabatically compressed. In an axially symmetrical electron gun, the electron beam becomes a hollow cylinder whose diameter gradually becomes smaller.

When the electrons reach a region with uniform magnetic flux density in the axial direction, they will have stable cyclotron motion. When a high-frequency electromagnetic field is applied in this state, the electrons interact with the high-frequency electromagnetic field. now,
We take one of the cyclotron orbits of electrons, apply a high-frequency electric field perpendicular to the axial magnetic flux, and consider the electron aggregation process. Electrons perform a circular motion on the cyclotron orbit, and when the high-frequency electric field and the direction of electron movement are the same, the electrons are accelerated and the phase of the cyclotron frequency is delayed. If the direction is opposite, the electron will be decelerated and its phase will advance. If the high-frequency electric field and the cyclotron motion of the electrons are perfectly synchronized, then the total energy of the electrons in the cyclotron orbit will always be constant when averaged. However, if the period of the high-frequency electric field is made slightly faster than the period of the cyclotron motion of the electrons, there will be more decelerated electrons on the cyclotron orbit than accelerated electrons. This phenomenon occurs due to the influence of relativistic effects due to the movement of electrons. In other words, the mass of an electron accelerated by a high-frequency electric field increases from its initial value due to the relativistic effect. On the other hand, the mass of the decelerated electron decreases from its initial value. As a result, after several cycles, the electrons on the cyclotron orbit are clustered in the deceleration region with a certain probability. As a result, the total energy of the electrons in the cyclotron orbit decreases on average, and the lost kinetic energy of the electrons contributes to an increase in the energy of the high-frequency electromagnetic field. Such interactions are known as cyclotron resonance masers (CRMs).

A microwave electron tube that uses a maser effect due to cyclotron resonance and uses an axisymmetric hollow cylindrical electron beam is called a gyrrotron. The type of Gyrrotron interacts with the electromagnetic field generated in a single resonant circuit such as a cavity resonator, and the kinetic energy of electrons is lost due to the electromagnetic wave energy accumulated in the resonant circuit, causing an oscillation phenomenon. the Gyromonotron, which uses multiple cavity resonators to utilize electromagnetic wave amplification, the GyroTWT, which uses the interaction between the electromagnetic field of a traveling wave in a transmission circuit and electrons moving in a cyclotron, and A backward wave gyrotron or the like can be considered by combining with the backward wave in the transmission circuit.
Of course, a combination of these characteristics can also be considered.

Various electromagnetic wave modes are possible in the high-frequency electromagnetic field that interacts with the electron beam accompanied by cyclotron motion. Fundamental and harmonic electromagnetic wave modes can be excited in resonance circuits and transmission circuits according to the respective circuit dimensions, resulting in a maser effect due to cyclotron resonance. Generally, the electromagnetic wave mode excited in the interaction region is transmitted through an output circuit provided in a collector for collecting the electron beam, and is extracted as electromagnetic wave energy through an output window that also serves as a vacuum wall. The space between the electron gun and the interaction area is designed to prevent transmission of electromagnetic waves and to block transmission of interacting electromagnetic wave modes. However, it must have an electron beam passage hole (drift tube).

A microwave electron tube using cyclotron resonance, which converts the kinetic energy of electrons into electromagnetic energy with high efficiency, requires mode selectivity of the electromagnetic wave mode excited in the resonance circuit and transmission circuit. For example, in the case of a gyromonotron, the electromagnetic wave mode generated in the axisymmetric aperture resonator is preferably TEons. However, the fundamental wave mode of such a resonator is TE ₁₁₁ , and there are countless harmonic electromagnetic wave modes. This may not necessarily excite the desired electromagnetic wave mode due to changes in the symmetry or shape of the resonator. In the above resonator,
An example is the excitation of TM ₁₁₁ , which has the same resonant frequency as TE ₀₁₁ . Therefore, the resonator of the gyroscope uses an L element, a C element, or a combination thereof as a frequency tuning mechanism, like the resonator of a velocity modulation tube (klystron), which is a conventional microwave tube. It was difficult to incorporate it into the system. This is because the change in the shape of the resonator causes the generation of various unnecessary modes, resulting in a loss of mode selectivity. Due to these difficulties, it has not been possible to arbitrarily change the resonant frequency of the resonator of the conventional gyroscope from the outside. That is,
It was fixed at a resonant frequency determined by the shape of the resonator originally constructed. This drawback is common to all types of gyrrotrons, and it has been difficult to change the characteristics of the resonant circuit and transmission circuit from outside.

The present invention aims to solve this drawback by making it possible to easily change the characteristics of the electromagnetic wave mode that interacts with an electron beam accompanied by cyclotron motion from the outside.

The present invention relates to a microwave electron tube in which an electron beam emitted from an electron gun undergoes cyclotron motion under the influence of a magnetic field and interacts with electromagnetic waves. It is characterized by being configured so that a part of it can slide on the inner wall. According to this invention, when electromagnetic waves are generated by a resonant circuit, the resonant frequency and Q characteristics can be changed. Also,
In the case of an electromagnetic wave transmission circuit, it is possible to change the transmission characteristics.

The details of this invention will be explained below with reference to the drawings.
Figure 1 shows the structure of the most typical gyromonotron, a microwave electron tube based on cyclotron resonance. In Figure 1, cathode 1
Electrons are emitted from the emitter surface 2 of. Cathode 1
is heated by applying heater power between the heater terminal 3 and the cathode terminal 4. Anode terminal 5 determines the potential of anode 6. The electric field between the cathode 1 and the anode 6 accelerates the thermionic electrons emitted from the emitter 2, and the control coil 7 determines the magnetic field applied to the emitter 2 so that the emitted electrons do not collide with the anode 6. It is bent by a magnetic field and begins to perform cyclotron motion. Further, the potential of the body 8 extracts electrons undergoing cyclotron motion, allowing them to proceed to the region of the drift tube 9. Furthermore, since the magnetic field applied by the main coil 10 gradually becomes stronger, the electrons are adiabatically compressed and the energy of their swirling motion increases. Of course, the body 8, anode terminal 5, cathode terminal 4, and heater terminal 3 are each insulated by alumina ceramic (Al ₂ O ₃ ), glass, or the like. The electrons that have reached the drift tube 9 pass through the aperture type resonator 11 while performing stable cyclotron motion due to the uniform magnetic field created by the main coil 10. Here main coil 1
When the cyclotron frequency of electrons due to the magnetic field created by 0 and the resonant frequency of the aperture resonator 11 are determined to satisfy the cyclotron resonance condition, the electrons moving in the cyclotron and the resonant frequency of the aperture resonator 11 are excited. It interacts with electromagnetic waves that can be used. At this time, when the electromagnetic wave energy stored in the aperture type resonator 11 becomes greater than the kinetic energy lost from the electrons, an oscillation phenomenon occurs. Such electromagnetic waves flow into the collector 13 through the eyeless 12. The inside of the collector 13 is an electromagnetic wave transmission circuit, and the electromagnetic waves are taken out to the outside through a ceramic window 14 provided for vacuum tightness. On the other hand, electrons that have lost their energy due to interaction with electromagnetic waves also enter the collector 13 through the eyeless 12, but since they are released from being focused by the magnetic field of the main coil 10, It gets caught in the inner wall and generates heat. The outer wall of the collector 13 allows the cooling medium flowing from the water cooling port 15 to pass through the cooling channel 16.
It spreads heat. Heat is then radiated to the outside via this cooling medium. In this example, there is a cooling channel 17 on the body side as well, so that heat generated on the body side can be radiated.

Now, the feature of this invention is that a part of the inner wall of the aperture type resonator 11 slides. The specific structure is shown in Figure 2. In FIG. 2, a slider 18 forming the inner wall of the eyeless 12 is movable. The slider 18 uses the inner wall of the aperture type resonator 11 and the inner wall of the transmission circuit 27 as sliding surfaces. Then, it is connected to the movable plate 20 via the support rod 19. The bellows 21 is designed to allow a slider 18 integrated with the movable plate 20 to move while maintaining an internal vacuum. The outside of the movable plate 20 is threaded, and a cylindrical tuner 23
By engaging with the screw cut inside the
Configure a differential mechanism. In other words, the same tone 23 is
It is fixed to a reference point by a fixing screw 26 using a support plate 25 via a bearing 24 made of Teflon or the like. In such a structure, the same tone 23
By rotating the slider 18, which is integrated with the movable plate 20 via the support rod 19, the slider 18 is moved. The support rod 19 passes through the guide hole 22. Slider 1
8 is movable, the size of the aperture type resonator 11 is
change without losing axial symmetry. This result changes the resonant frequency of the aperture type resonator 11,
Q characteristics can be changed. Q of aperture type resonator 11
As for the characteristics, if the length in the axial direction is increased, the Q value can be increased, and if the Q value is high, the electric field strength of electromagnetic waves that interact with electrons will increase. Note that in the resonance mode of TEons, there is no need to contact the sliding surface of the slider 18 with a spring finger or the like. because,
This electromagnetic wave mode does not have an axial electric field, so no current flows in the axial direction. For this reason, the contact conditions of the sliding surfaces can be almost ignored.

It goes without saying that the sliding structure according to the present invention can be applied to various types of gyrrotrons. and,
With this invention, various characteristics of the circuit can be easily changed from the outside without losing the axial pairability of the electromagnetic wave resonant circuit or transmission circuit, and without changing the shape into a shape that tends to generate unnecessary electromagnetic wave modes. This makes it possible to provide a microwave electron tube with possible cyclotron resonance.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a gyroscope, which is a typical microwave tube based on cyclotron resonance. Figure 3 shows a cross-sectional view of a structure in which a part of the inner wall of a resonant or transmission circuit is slidable. In the figure, 1... cathode, 2... emitter, 3...
Heater terminal, 4... cathode terminal, 5... anode terminal, 6... anode (electrode), 7... control coil, 8... body, 9... drift tube, 10...
... Main coil, 11 ... Open resonator, 12 ... Airless, 13 ... Collector, 14 ... Output window, 15 ... Water cooling port, 16, 17 ... Cooling channel, 18 ... Slider, 19...Support rod, 20...
Movable plate, 21... bellows, 22... guide hole,
23...Same tone, 24...Bearing, 25...
Support plate, 26...fixing screw, 27...transmission circuit.

Claims (1)

[Claims] 1. The electron beam emitted from the electron gun is combined with the electron beam when the cyclotron frequency of the electrons due to the magnetic field created by the main coil 10 and the resonance frequency of the aperture type resonator 11 satisfy a resonance condition. In a microwave electron tube in which the electromagnetic waves of the aperture type resonator 11 interact, the aperture type resonator 11
A microwave electron tube using cyclotron resonance, characterized in that a slider 18 constituting the inner wall of the eyeless 12 can slide on the inner wall of the aperture type resonator 11 and the inner wall of the transmission circuit 27 as sliding surfaces.