JPH01189837A - Microwave tube - Google Patents

Abstract

PURPOSE:To efficiently convert the energy of electrons into the energy of microwaves by making a space formed by a cathode section and an accelerating electrode an oblique electromagnetic field space. CONSTITUTION:Electrons emitted from a cathode section 6 are applied with the rotating motion and circulating motion by the oblique electromagnetic field existing between the cathode section 6 and an accelerating electrode section 7. When the potential of the accelerating electrode 7 is set to the potential not capturing electrons, electrons depict a spiral orbit 15 and are moved toward an electron interaction space 5 along the magnetic field distribution, the axis of the spiral orbit gradually approaches the axis of an anode cylinder, the pitch of the spiral orbit is gradually decreased. The pitch of the spiral orbit at the cathode section 6 side of the electron interaction space is not sufficiently decreased as compared with that at the outlet side, thus an inclination corresponding to the pitch is applied to a vane 2 to efficiently generate the microwave energy from electrons on the orbit. The vane section 4 existing on the inlet side of the electron interaction space has an inclination angle of about 5-25 deg. against the axis of the anode cylinder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microwave tube used as a microwave generating means when performing dielectric heating.

BACKGROUND OF THE INVENTION A typical conventional microwave tube of this type was a magnetron. A magnetron has a structure in which a cathode part and an anode part which also serves as an accelerating electrode are arranged concentrically, and an orthogonal electromagnetic field is formed in the electron action space. Electrons emitted from the cathode part orbit around the cathode while making a circular motion in this action space.

At this time, the sum of the angular frequency of the swirling motion and the angular frequency of the circular motion corresponds to the cyclotron angular frequency. By the way, it is known that in a uniform magnetic field space without an electric field, electrons rotate at the cyclotron angular frequency.

The orbiting motion of electrons in a weak magnetron is generated by an electric field or anode-cathode pressure, and as the voltage increases, the angular frequency of the orbiting increases. Furthermore, the magnetron uses the potential energy of the a-child as a microphone by synchronizing the circulating angular frequency with the angular frequency defined by the anode part. However, it is very difficult to realize the following with this magnetron. The challenge is low voltage drive. From the above, when the voltage between the anode and the cathode is lowered, the orbiting angular frequency of electrons becomes smaller.

Therefore, it is necessary to reduce the angular frequency defined by the anode section. This angular frequency w0 is the oscillation frequency and +2πf. Using the number N of resonant circuits at the pole, Wo-/(N/2)
is given by Therefore, under certain conditions, it is necessary to increase N. When the anode-cathode voltage is, for example, 200 volts, N is preferably as large as possible, such as 40 or more. However, even if such a positive part can be designed, it is extremely difficult to manufacture. Therefore, the conventional microwave tube has a problem in that it does not have a structure suitable for low voltage driving.

A first object of the present invention is to provide a new microwave tube that solves the problems of the conventional method.

The second purpose is to efficiently convert the potential energy of electrons into microwave energy.In order to solve the above problems, the microwave tube of the present invention has a structure in which the cathode part and the anode part are separated. . That is, a plurality of vanes arranged radially within an anode cylinder form an anode section, and an electron action space (no cathode section exists) is formed in the center of the anode section.

The cathode section is separated from the electron action space and arranged concentrically with the anode cylinder. The cathode side of the vane is inclined at a predetermined angle with respect to the axis of the anode cylindrical tube. The cathode section has a conical outer shape that tapers toward the electron action space, and an accelerating electrode is arranged around it concentrically with the cathode section. Furthermore, at one end of the anode portion side of the anode cylinder, there is a first tube having a structure in which the center part protrudes inside the anode cylinder.
A second pole piece having a planar structure is provided at the other end of the pole piece. Furthermore, magnetic field generating means is provided adjacent to each pole piece.

Operation According to the above-described configuration of the present invention, the space created by the cathode section and the accelerating electrode becomes an oblique electromagnetic field space.

For this reason, the electrons emitted from the cathode perform swirling and orbiting motions, but if the potential of the accelerating electrode is set to a voltage that prevents these electrons from being captured by the accelerating electrode, the electrons will rotate and orbit along the magnetic field distribution. Moves in a spiral trajectory. By the way, by using the above pole piece structure, the magnetic field distribution becomes a distribution that widens from the anode side to the cathode side. Therefore, the axis of the helical orbit of the electron gradually approaches the axis of the anode cylindrical tube. At this time, the pitch of the helical orbit also gradually decreases. Although the pitch of this helical trajectory is relatively large near the entrance of the working space, energy conversion is performed efficiently by arranging the vanes in accordance with this pitch angle. Since all the electrons emitted from the entire circumference of the cathode move in the same way, the electrons become concentrated as they reach the center of the anode. The movement of these electrons is centered on swirling motion. Therefore, the number of resonant cavities (i.e., the number of vanes) in the anode section to synchronize the movement of electrons is 10 to 2.
This can be achieved with 0, and low voltage driving can be achieved.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, reference numeral 1 denotes an anode cylinder, and a plurality of vanes 2 are arranged radially inside the anode cylinder. This vane 2 is composed of a portion 3 parallel to the tube axis of the anode cylinder and a portion 4 inclined to the tube axis. The central portion surrounded by the vane group is the electron action space 5. Further, a cathode section 6 is disposed concentrically with the anode cylinder on the tube axis of the anode cylinder. The external shape of this cathode section 6 is narrow (
It has a conical shape. Further, an accelerating electrode section 7 is arranged concentrically with the cathode section 6. At one end of the anode cylinder on the side where the vanes are arranged, there is a first pole piece 8 whose center part protrudes into the inside of the anode cylinder, and at the other end there is a second pole piece 9 having a planar shape. A first magnetic field generating means 10 and a second magnetic field generating means 11 are arranged adjacent to the pole piece. A yoke 12 is also provided to form an external magnetic circuit. With such a magnetic circuit structure, a magnetic field distribution shown by the dotted line in FIG. 1 is formed within the anode cylinder. The portion of the accelerating electrode section 7 facing the cathode section 6 is structured such that the direction of the electric field intersects the above magnetic field distribution at an acute angle when viewed from the vane side.

13 is an antenna lead that guides the microwave generated at the anode to the outside.

14 is an output antenna section.

In such a configuration, the electrons emitted from the cathode section 6 undergo swirling and circumferential motion due to the oblique electromagnetic field existing between the cathode section and the accelerating electrode section.

At this time, the potential of the accelerating electrode is set to a potential (about several hundred volts) that does not capture electrons (in fact, only a few electrons are captured). As a result, the electron moves into a spiral orbit 15 as shown in Figure 2.
The electron moves in two directions in the action space while following the magnetic field distribution. At this time, the orbit axis of the helical orbit gradually approaches the tube axis of the anode cylinder, and the pitch of the helical orbit gradually becomes smaller. The pitch of the helical orbit on the entrance side (cathode side) of the electron action space is not yet sufficiently small compared to the exit side. Therefore, in order to efficiently generate microwave energy from the electrons on these orbits, the vanes are provided with an inclination corresponding to the pitch of the electrons. A perspective view of the vane is shown in FIG. That is, the vane portion 4 existing on the entrance side of the electron action space is inclined at a predetermined angle with respect to the axis of the anode cylindrical tube. This inclination angle is preferably 5° to 25°.

Electrons emitted from the entire circumference of the cathode draw similar orbits and are concentrated in the electron action space 5. The rotational movement of electrons within the electron action space is a swirling movement. Its rotational angular frequency therefore corresponds to the cyclotron angular frequency. Further, this angular frequency is approximately the same magnitude as the circulating angular frequency in a conventional magnetron. Therefore, although the microwave tube of the present invention is driven at a low voltage of several hundred volts or less, the number N of resonant cavities in the anode portion can be approximately 10 to 20.

Effects of the Invention As described above, the microwave tube of the present invention provides the following effects.

(1) Since the anode portion and the cathode portion are separated and the magnetic circuit is configured such that electrons emitted from the cathode are concentrated in the electron action space of the anode portion, it is possible to provide a microwave tube driven at a low voltage.

(2) Since the vanes are tilted with respect to the tube axis in accordance with the spiral trajectory of the electrons, the energy possessed by the electrons can be efficiently converted into microwave energy.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a microwave tube showing an embodiment of the present invention, Fig. 2 is a sectional view showing the movement trajectory of electrons in the microwave tube, and Fig. 3 is a perspective view of essential parts of the microwave tube. It is. 1... Anode cylinder, 2... Vane, Yu.
...The part parallel to the pipe axis of the vane, the soil...
The part of the vane that is inclined to the tube axis, 6...the cathode part,
7... Accelerating electrode section, 8... First pole piece, 9... Second pole piece, 10.
11...Magnetic field generating means. Name of agent: Patent attorney Toshi Nakao Haka1/-
---Sumidori Enka 2----: Men, 2-----To 'in' pipe lte child row rJ outside /θ//-
--Ei Bian Chao Sheng Child Actor Figure 1

Claims (1)

[Claims] an anode tube; a plurality of vanes arranged radially within the anode tube; A cathode part, which is arranged concentrically with the anode cylinder and separated from the vane on the side having the sloped part of the vane, and whose outer shape is narrower toward the vane side; and a cathode part surrounding the cathode part. an accelerating electrode part arranged concentrically; a first pole piece arranged at the end of the anode cylinder on the side where the vane is arranged, the center part of which protrudes into the inside of the anode cylinder;
a second pole piece having a planar configuration disposed at the other end of the anode tube; a first magnetic field generating means disposed close to the first pole piece; and a second pole piece disposed close to the second pole piece. a second magnetic field generating means arranged therein.