JPH02132736A - Large power klystron - Google Patents

Abstract

PURPOSE:To stably derive a big power microwave by constituting an output cavity of plurality of columnar cavities having holes for external connection respectively, while an output waveguide is made a waveguide being jointed so as to cover the respective connection holes of these cavities in a lump while being long in the beam stream direction for becoming gradually smaller as it goes outward. CONSTITUTION:An output cavity 14 consists of two-piece columnar cavities 14A and 14B having holes 10 for external connection respectively, while an output waveguide 16 is jointed so as to cover both external connection holes 10. This output waveguide 16 is made gradually smaller as it goes outward for being made an output end. In this case, as the waveguide goes away from the output cavity 14, it becomes short gradually as well as by a smooth boundary ranging a longer distance at least than the klystron operation wavelength for being connected to a standard waveguide. That is, this tapered part 16a becomes matching with a standard waveguide. Thereby, output power becomes stabilized without generating reflection.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) This invention relates to a beam straight-travel type high-power klystron,
In particular, it relates to improvements in its output cavity and output waveguide.

(Prior Art) In general, a beam straight-travel type high-power klystron, as shown in FIG. Electronic action part 6
, a collector 7 , an input waveguide 8 , and an output waveguide 9 .

During operation, the electron beam emitted by the electron gun 1 is velocity-modulated by an input signal introduced into the input cavity 2 from the input waveguide 8, and is gradually changed to density modulation by the intermediate cavity 3 and the drift tube 5. By passing the density-modulated electron beam through the gap in the output cavity 4, amplified microwaves are obtained from the output cavity 4 and extracted from the output waveguide 9. At this time, the used electron beam is captured by the collector 7.

By the way, the conventional output cavity and output waveguide are shown in Fig. 3 (
Constructed as shown in a) and (b), one output cavity 4
An output waveguide 9 is coupled to cover the external coupling hole 10 . Note that 11 is an output window.

In another conventional example, as shown in FIGS. 4(a) and 4(b), an output waveguide 9 is coupled to one of the output cavities 12 consisting of two cavities 12A and 12B. ing. In addition, 13
is a coupling hole that couples both cavities 12A and 12B.

(Problems to be Solved by the Invention) In the conventional example shown in FIGS. 3(a) and 3(b), a large electric field is generated in the gap between the output cavities 4 when attempting to obtain a high output microwave. Since this leads to discharge, the output value that can be obtained from one klystron is limited.

In addition, in the conventional example shown in FIGS. 4(a) and 4(b), the klystron has an output cavity 12 consisting of two cavities 12A and 12B coupled to each other, and the electric field generated in the gap between one cavity is , is considered to be approximately proportional to the square root of the microwave power applied to the cavity from the electron beam. Therefore, if two cavities 12A and 112B are provided, each cavity 12A, 12
The idea is that high-power microwaves can be obtained while the electric field generated in the gap B is suppressed to a value that poses no risk of discharge.

However, the generated microwaves are transmitted through the external coupling hole 1.
In the cavity 12A to which the output waveguide 9 is coupled, a large microwave power is concentrated.

For this reason, this type of klystron cannot necessarily be expected to operate stably with high power. Also, because they are mutually coupled, depending on a certain frequency or speed of the electron beam,
This causes unstable conditions such as oscillation.

This invention was made in view of the above circumstances, and allows stable high-power microwave generation while suppressing the electric field strength in each gap between output cavities consisting of a plurality of columns of cavities to a value that does not pose the risk of electrical discharge. The purpose is to provide a high-power klystron that enables output.

[Structure of the Invention (Means for Solving the Problems)] This invention is characterized in that the output cavity is composed of a plurality of columns of cavities each having an external coupling hole, and the output waveguide is composed of a plurality of columns of cavities each having an external coupling hole. A high-power klystron is a waveguide that is long in the beam flow direction and is connected so as to collectively cover each coupling hole in the cavity, and is gradually shortened as it goes outward to serve as the output end. be.

(Operation) According to the present invention, it is possible to stably derive a high-power microwave as a whole while suppressing the electric field strength in the gaps between the cavities constituting the output cavity to a value that does not pose a risk of discharge.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The vicinity of the output cavity of the high-power klystron according to the present invention is configured as shown in FIGS. 1(a) and (b), and (a)
) is a longitudinal cross-sectional view, and (b) is a cross-sectional view.

That is, the same parts as in the conventional example (Fig. 3) are given the same reference numerals, and the output cavity 14 consists of two columns of cavities 14A and 14B each having an external coupling hole 10. The peripheral edge portion 10a of 10 serves as an aperture that provides an appropriate external Q value to each cavity 14A, 14B. Further, 15 in the figure (a) is a coupling portion that guides the microwave power generated in each cavity 14A, 14B to the outside.

The output waveguide 16 is coupled so as to cover both external coupling holes 1o of the output cavity 14.

The output waveguide 16 is a rectangular waveguide long in the beam flow direction, and its length is approximately equal to the length from the beam upstream side to the beam downstream side of the output cavity 14.

Further, as is clear from the figure (a), the output waveguide 16 is gradually shortened toward the outside to form the output end. In this case, away from the output cavity 14, it is gradually shortened by a smooth boundary (Taber section 16a) over a distance at least longer than the klystron operating wavelength and connected to a standard waveguide. That is,
The tapered portion 16a matches the standard waveguide, and an output window 11 is provided near the tip. The position of this output window 11 is not limited, and for example, the number of output windows 11 may be provided in the coupling portion 15 as many as the number of cavities.

Additionally, the output waveguide 16 has a greater height in the electric field direction than a standard waveguide.

Note that the high-power klystron of the present invention has the same configuration as that shown in FIGS. 2 and 3 except for the above, and therefore detailed explanation will be omitted.

Now, assuming that the output power is Po, and that the output power is uniformly obtained from the N cavities forming the output cavity, the high frequency voltage generated in each cavity gap is P o /N. By increasing N, the high frequency voltage can be lowered and discharge can be suppressed.

Further, the output power is taken out equally from each cavity in a direction substantially perpendicular to the tube axis, so that no discharge occurs due to concentration of power in some cavities.

Furthermore, the output power gradually and smoothly increases (Taber part 1
6a), it does not cause reflections and is therefore stable.

In addition, if it is not necessary to use a standard waveguide, there is no need to provide the tapered part 16a, and if the waveguide is directly guided with a high height in the electric field direction without using the tapered part 16a, the inside of the waveguide can be discharge can also be suppressed.

In the above embodiment, two output cavities are arranged in tandem, but the configuration is not limited to this, and a plurality of cavities such as three or four cavities may be arranged, and the coupling holes of each cavity may be connected at once. What is necessary is to provide an output waveguide so as to cover it.

[Effects of the Invention] According to the present invention, the output cavity is composed of a plurality of columns of cavities each having an external coupling hole, and the output waveguide collectively connects each coupling hole of these cavities. The waveguide is long in the beam flow direction and is gradually shortened as it goes outward, so that the electric field strength in the gap between the winter cavities that make up the output cavity can be reduced without the risk of discharge. It is possible to stably derive high-power microwaves overall while suppressing the value to a certain value.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are longitudinal and cross-sectional views showing the main parts (near the output cavity) of a high-power klystron according to an embodiment of the present invention, and FIG. 2 is a general high-power klystron. A schematic cross-sectional view showing the entire klystron, FIGS. 3(a) and (b) are a vertical cross-sectional view and a cross-sectional view showing the main part (near the output cavity) of a conventional high-power klystron, and FIG. 4(a) , (b) are a vertical cross-sectional view and a cross-sectional view showing the main part (near the output cavity) of another conventional high-power klystron. DESCRIPTION OF SYMBOLS 1... Electron gun, 2... Input cavity, 3... Intermediate cavity, 5... Drift tube, 7... Collector electrode, 10...
... External external coupling hole, 14... Output cavity, 14A,
14B...Cavity, 16...Output waveguide. Figure 2

Claims (1)

[Claims] An input cavity, a plurality of intermediate cavities, an output cavity, and a collector electrode are arranged in series along an electron beam path from an electron gun, and an output waveguide is coupled to the output cavity. In a high power klystron, the output cavity is composed of a plurality of columns of cavities each having an external coupling hole, and the output waveguide collectively connects each coupling hole of the plurality of columns of cavities. A high-power klystron characterized by a waveguide that is long in the direction of beam flow and coupled in a covering manner, and gradually becomes shorter and smaller as it goes outward to form an output end.