JPH0428148A - Gyrotron with built-in mode converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a gyrotron. More specifically, the present invention relates to a high frequency output structure of a gyrotron that is useful as a high frequency high power source in the submillimeter wave band.

(Prior art and its problems) A gyrotron is an electron tube whose operating principle is cyclotron maser action, and has been used as a high-frequency high-power source in the millimeter to submillimeter wave band. The types of gyrotrons include, for example, 1) a cylindrical electron beam formed by a group of electrons moving in a cyclotron; and a resonant circuit formed by the interaction of this electron beam with electromagnetic waves in one resonant circuit such as a resonant cylinder; 2) A gyromonotron, which loses the energy of an electron beam and oscillates due to the electromagnetic energy accumulated in it; 2) a gyroklystron, which uses a similar electron beam and multiple resonant cavities to amplify electromagnetic waves; 3) ) A gyro traveling wave tube that uses similar interaction between an electron beam and a traveling wave in a transmission circuit, and 4) a backward wave gyrotron that uses a coupling with a traveling wave in a transmission circuit.

These conventional gyrotrons have an output of about 200K14, and can be used as a high-frequency transmission path for oscillating electron beam collectors. Additionally, an output ceramic window is usually installed downstream of this collector.

On the other hand, as the oscillation output of the gyrotron increases to about 500K14 or more, the high-frequency oscillation mode generates less heat in the high-frequency circuit than the T E on mode (n is a natural number), which is the conventional axis-symmetric mode. In addition, an output mode called a corridor mode, which has less competition between oscillation modes, has come into use. The electric field distribution in the waveguide in the corridor mode and the manner in which the electromagnetic wave in the corridor mode propagates in the radio waveguide are shown, for example, in Figures 1 and 2, respectively.
This can be illustrated in the figure.

As illustrated in Figure 1, the electric field distribution consists of electric lines of force (11)
As shown in FIG. 2, the electromagnetic waves (21) in the corridor mode propagate in the direction of the arrow in the waveguide, as shown in FIG.

Furthermore, when using such a corridor mode, it is necessary to increase the inner diameter of the collector in consideration of its heat resistance, but increasing the inner diameter of the collector may reduce high frequency transmission efficiency. Therefore, as illustrated in Fig. 3, a Blazov converter consisting of a radiator (31) and a reflector (32) is installed downstream of the high-frequency circuit, thereby converting the high-frequency power in the corridor mode into an electromagnetic beam (33).
The gyrotron is emitted as an output signal and output to the outside of the gyrotron through a ceramic output window provided on the side of the gyrotron.

This makes it possible to separate the collector section and the output circuit, and also solves the problem of heat load on the collector.

However, although efforts have been made in this way,
In the case of the conventional corridor mode Blazov transformer, the diffraction effect at the cut portion (34) shown in FIG. 3 is large, and scattering of electromagnetic waves inevitably occurs, resulting in a decrease in high frequency output. Furthermore, due to the asymmetry in the structure, there is a possibility that the radiated power distribution will be distorted when high-frequency power is radiated to the outside of the gyrotron, and in this case, there is also the disadvantage that the shape of the reflector becomes complicated.

This invention solves the drawbacks of conventional means such as the Blazov transformer for utilizing the corridor mode as described above, and provides a new gyro capable of outputting an electromagnetic wave beam having a crow-shaped electromagnetic field distribution with excellent high frequency transmission characteristics. The purpose is to provide Tron.

(Means for Solving the Problems) The present invention solves the above problems by converting a corridor mode into an axisymmetric circular mode (TEo) downstream of a high frequency circuit section.
A hollow Thunt-type mode converter is installed to convert the high-frequency output of the corridor mode into a circular mode, and a plane-symmetric circular mode electromagnetic wave radiator and a reflector are installed downstream of the mode converter. The present invention provides a gyrotron characterized in that a Gaussian beam with good symmetry is outputted to the outside of the gyrotron through a ceramic output window by shaping the beam power distribution using the reflector plate.

According to the present invention, high-power high-frequency power can be output from the gyrotron as a Gaussian electromagnetic beam with good symmetry suitable for long-distance transmission.

(Example) The present invention will be described in more detail below with reference to the attached drawings.

FIG. 4 is a schematic cross-sectional view showing an example of the gyrotron of the present invention. For example, as shown in Figure 4,
The gyrotron of the present invention generates a hollow beam along an electron beam path (42) in an electron gun part (41), and a tapered electron beam introduction part (43) whose inner diameter is gradually reduced, and a downstream part of the beam. A resonant whole wound part <44) that was continuously provided in the It has a reflector plate (47) for reflecting and shaping the radiated high frequency power. This gyrotron also includes a collector section (48) that absorbs electron beams, a high-frequency output section (49), a ceramic output window <50), and a cryostat (51) that houses a superconducting coil for generating a magnetic field.
It also has the following. The electromagnetic wave beam emitted by the radiator (46) is output along an output path (52).

In this device, the electron beam exiting the electron gun (41) is guided by a strong magnetic field in the axial direction.
) and enters the resonant cavity (44), where the energy of the electron beam is converted into energy of electromagnetic waves. After this, the electrons pass through the mode converter (45>), the radiator (46), and are absorbed by the collector section (48).The resonant cavity section (
The high-power high-frequency waves in the corridor mode generated in 44) are mode-converted from the corridor mode to a circular axis-symmetric mode (TEon) using a Tull type converter (45), and are converted into stepped (Blasov type) or obliquely cut radiation. The radiation is emitted from the reflector (46) to the reflector (47), and the output ceramic window (50
) is output to the outside as a Gaussian electromagnetic wave.

FIGS. 5(a) and 5(b) show examples of the structure of the stepped (Blasov type) radiator (46) and reflector (47) illustrated in FIG. 4. This radiator (46) converts the circular mode into a Gaussian spatial electromagnetic wave beam.

As shown in FIG. 5, the circular mode electromagnetic waves are radiated from the radiator (46) in a semi-cylindrical shape with the central axis as the wave source, and are further converted into a transmission electromagnetic beam (
53). A Gaussian electromagnetic beam is obtained.

(Effects of the Invention) According to the present invention, as explained in detail above, the output of the gyrotron can be efficiently converted from the oscillation mode, which is the corridor mode, to a Gaussian electromagnetic beam with low diffraction loss and good symmetry. .

Therefore, higher-order modes lost during electromagnetic wave radiation and waveguide transmission are controlled, and a gyrotron having a high-frequency system with high energy utilization efficiency can be constructed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the electric field distribution of the corridor mode within the waveguide. FIGS. 2(a) and 2(b) are schematic cross-sectional views showing the progression of electromagnetic waves in a corridor mode within a waveguide. Figure 3 (
Figures a and b are schematic cross-sectional views showing a Blazov transformer that converts a corridor mode into a spatial electromagnetic beam. FIG. 4 is a schematic cross-sectional view illustrating the gyrotron of the present invention. FIGS. 5(a) and 5(b) are schematic cross-sectional views illustrating a Blazov transformer used in the present invention for converting a circular mode into a spatial electromagnetic beam. 11... Electric lines of force 21... Electromagnetic waves 31... Emitter 32... Reflector plate 33... Electromagnetic beam 34... Cutting section 41... Electron gun section 42... Electron beam 43 ...Electron beam introducing section 44...Resonance cavity section 45...Circular mode generation mode converter 46...Radiator 47...Reflector plate 8...Collector section 9...High frequency output Part 0... Ceramic output window 1... Cryostat 2... Electromagnetic wave beam path 3... Electromagnetic beam

Claims (1)

[Claims] (1) A high frequency circuit section including an electron gun section, an electron beam introduction section and a resonant cavity provided downstream of the electron gun section, and a collector section provided separately downstream of the high frequency circuit section, through which high frequency waves are passed. Equipped with a ceramic output window section, and further,
A mode converter that converts the high frequency power generated from the high frequency circuit section into a circular mode, and a radiator and a reflector that radiate the high frequency power to the outside of the gyrotron through the output window section downstream of the mode converter. A gyrotron with a built-in mode converter.