JP4342043B2 - Multi-cavity klystron device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-cavity klystron apparatus that operates at a plurality of discrete frequencies.
[0002]
[Prior art]
A multi-cavity klystron apparatus is an apparatus that amplifies a high-frequency signal by utilizing an interaction with an electron beam, and is used for amplifying a high-frequency signal such as a microwave.
[0003]
Here, a conventional klystron apparatus will be described with reference to FIG. Reference numeral 41 denotes an electron gun, and an input cavity 42 and three intermediate cavities 43, an output cavity 44, and a collector for capturing the electron beam e along the traveling direction of the electron beam e generated by the electron gun 41. 45 etc. are provided. The input cavity 42 is provided with an input coupling loop 46 for inputting a high frequency signal to be amplified. An output waveguide 47 for extracting the amplified high frequency signal is connected to the output cavity 44. In addition, an output window 48 is provided in a part of the output waveguide 45 to keep the inside of the klystron vacuum-tight and transmit high-frequency output. Further, a drift pipe D is connected between the input cavity 42 and the intermediate cavity 43, between the intermediate cavities 43, and between the intermediate cavity 43 and the output cavity 44. Moreover, the code | symbol M has shown the pipe axis.
[0004]
In the configuration described above, a high frequency signal is input to the input cavity 42 through the input coupling loop 46. The input high-frequency signal is amplified by interaction with the electron beam e, output from the output cavity 44 to the output waveguide 47, and taken out through the output window 48.
[0005]
FIG. 5A is a view of the cavity portion viewed from the traveling direction of the electron beam, and reference numeral G denotes a gap tube positioned in the cavity portion. FIG. 5B shows the electric field distribution in the cavity portion. The horizontal axis represents the diameter direction (L) of the cavity, and the vertical axis represents the electric field strength (E).
[0006]
[Problems to be solved by the invention]
In the conventional multi-cavity klystron apparatus, in order to obtain a large gain when taking out an amplified high-power high-frequency signal, the band is usually narrowed to 1% or less of the operating frequency so as to operate at a single frequency. Yes.
[0007]
However, the S-band linac employs two operating frequencies separated by several percent, such as 2856 MHz and 2998 MHz. When operating at two frequencies in this way, for example, a tuner is provided in the cavity so that the resonant frequency of the cavity can be adjusted. However, if a tuner is provided in the cavity portion, it becomes difficult to cope with a large output. Therefore, in order to obtain a large output whose operating frequency differs by several percent, a plurality of multi-cavity klystron apparatuses each having a necessary operating frequency are used.
[0008]
The present invention solves the above-described drawbacks, and an object thereof is to provide a multi-cavity klystron apparatus that operates at a plurality of operating frequencies.
[0009]
[Means for Solving the Problems]
The multi-cavity klystron apparatus according to the present invention receives a plurality of electron guns each generating an electron beam and an input signal amplified by the interaction with the electron beam, and is provided for each electron beam. A plurality of coupled input cavities, a plurality of intermediate cavities positioned on the traveling side of the electron beam of each of the input cavities and coupled to each other by at least one for each electron beam; and In a multi-cavity klystron apparatus comprising a plurality of output cavities provided for each electron beam on the traveling side of the electron beam and coupled to each other for extracting an amplified output signal, and a collector for capturing the electron beam . A first branch having two output cavities, a first output cavity and a second output cavity, to which a first output waveguide coupled to the first output cavity is connected. And a second branch to which a second output waveguide coupled to the second output cavity is connected, a signal input to the first branch and a signal input to the second branch are synthesized in phase. A magic T having a fourth branch in which a signal input to the branch, the signal input to the first branch, and a signal input to the second branch are combined in opposite phases; and the third branch and the fourth branch, respectively, An output window matched to different frequencies is provided .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. Reference numerals 11A and 11B are two electron guns provided adjacent to each other. Then, along the traveling directions of the electron beams ea and eb generated by the two electron guns 11A and 11B, the input cavities 12A and 12B and the three intermediate cavities 13A and the input cavities are input for each electron beam. 13B and output cavities 14A and 14B for outputting the amplified signals are arranged. Further, collectors 15A and 15B for capturing an electron beam are provided at the ends of the output cavities 14A and 14B.
[0011]
One of the input cavities 12A and 12B, for example, the input cavity 12A, is provided with an input coupling loop 16 for inputting a high-frequency signal to be amplified. One of the output cavities 14A and 14B, for example, the output cavity 14A, is connected to an output waveguide 17 for extracting an amplified high frequency signal. In addition, an output window 18 is provided in part of the output waveguide 17 to keep the inside of the klystron vacuum-tight and to transmit a high-frequency output.
[0012]
Further, a drift pipe Da connects the input cavity 12A and the intermediate cavity 13A positioned along the traveling direction of one electron beam ea, the intermediate cavity 13A, and the intermediate cavity 13A and the output cavity 14A. Has been. Further, the drift tube Db connects the input cavity 12B and the intermediate cavity 13B positioned along the traveling direction of the other electron beam eb, the intermediate cavities 13B, and the intermediate cavity 13B and the output cavity 14B. Has been. Then, the input cavity 12A and the intermediate cavity 13A and the output cavity 14A arranged along the traveling direction of one electron beam ea, and the input cavity 12B disposed along the traveling direction of the other electron beam eb. In the intermediate cavity 13B and the output cavity 14B, the corresponding cavities are arranged at the same position in the traveling direction of the electron beam, that is, in the tube axis direction.
[0013]
The cavities at the same position are coupled to each other through a coupling port. Note that reference numerals M1 and M2 denote tube axes.
[0014]
Here, a pattern in which cavities at the same position are combined will be described with reference to FIG. FIG. 2 (a) is a view of the cavity portion viewed from the direction of the electron beam. Reference symbol P indicates a cavity arranged along the traveling direction of one electron beam ea, and reference symbol Q indicates the other. A cavity disposed along the traveling direction of the electron beam eb is shown. The cavity P and the cavity Q are arranged at the same position in the tube axis direction. The cavity P and the cavity Q are coupled through a coupling port C. Reference symbol G denotes a gap tube located in the cavity portion.
[0015]
In the configuration described above, the high frequency signal to be amplified is input to the input cavities 12A and 12B through the input coupling loop 16. The input high frequency signal generates an electric field in the gap tubes of the input cavities 12A and 12B. The electron beams ea and eb are subjected to velocity modulation by this electric field. The velocity modulation of the electron beams ea and eb corresponds to the frequency of the input signal, and the electron beams ea and eb travel in the direction of the output cavities 14A and 14B while interacting with the electromagnetic field of the intermediate cavity. The amplified output signal is output to the output waveguide 17 from the output cavities 14A and 14B. Thereafter, the amplified output signal is taken out of the tube through an output window 18 provided in the output waveguide 17.
[0016]
By the way, in the multi-cavity klystron apparatus described above, cavities arranged at the same position along the two electron beams ea and eb are coupled to each other. In this case, two resonance modes are generated in the cavity portion at the same position, as shown in FIG. 2B, a zero mode having a frequency of f1, as shown in FIG. 2C, and a π mode having a frequency of f2, as shown in FIG. To do. The horizontal axes of (b) and (c) in the figure indicate the direction (L) connecting the centers of the cavities at the same position, and the vertical axis indicates the magnitude (E) of the electric field.
[0017]
In the zero mode shown in FIG. 2B, the electric field is maximized at the central portion of the two cavities P and Q, and both electric fields are in phase. In the π mode shown in FIG. 2C, the electric field is maximum at the centers of the two cavities P and Q, and the phases of the electric fields are 180 degrees different from each other. In this case, the resonance frequency f0 of the zero mode and the resonance frequency fπ of the π mode are expressed by the following equations when the resonance frequency f unique to each cavity is the same and the coupling coefficient is k.
f0 = (1-k) * f
fπ = (1 + k) × f
Therefore, if the resonance frequency f and the coupling coefficient k between the cavities are set to predetermined values, the values of f0 and fπ can be arbitrarily determined. In this case, if the frequencies f0 and fπ are made to correspond to the two detuned operating frequencies f1 and f2 (f1 <f2), a multi-cavity klystron apparatus that operates at a plurality of different frequencies can be realized.
[0018]
For example, when a low operating frequency f1 is excited in the input cavity, each cavity is excited in zero mode. In this case, the two electron beams are bunched in the same phase and enter the intermediate cavity and the output cavity in the same phase, and each intermediate cavity and the output cavity are excited in the zero mode. As a result, velocity modulation is performed at the resonance frequency of the zero mode, and energy is converted to a high frequency in the output cavity.
[0019]
When a high operating frequency f2 is excited in the input cavity, each cavity is excited in the π mode. In this case, the two electron beams are bunched in opposite phases and enter the intermediate cavity and the output cavity in opposite phases, and each intermediate cavity and output cavity are excited in the π mode. As a result, velocity modulation is performed at the resonance frequency of the π mode, and energy is converted to a high frequency in the output cavity.
[0020]
As a method of extracting the outputs of the two operation modes described above, for example, there is a method of providing output windows that are matched to the two operation modes and taking out the signals of the two operation modes from the matched output windows, respectively. . In addition, each of the two output cavities is provided with irises, and outputs are taken out from the two output cavities, and the magic T connected to the same electrical length position from each output cavity is used for each operation mode. There is a way to extract the output.
[0021]
Here, a method of taking out the outputs of the two operation modes using the magic T will be described with reference to FIG. 3 showing the vicinity of the output cavity. In FIG. 3, parts corresponding to those in FIG.
[0022]
As shown in FIG. 3A, the first output waveguide 17A is connected to one output cavity 14A, and the second output waveguide 17B is connected to the other output cavity 14B. FIG. 3B schematically shows the structure of the magic T31. The first output waveguide 17A is connected to the first branch 311 of the magic T31, and the second output waveguide 17B is the first output waveguide 17B. It is connected to the two branch 312.
[0023]
In addition, the magic T31 combines and outputs the inputs of the first branch 311 and the second branch 312 in the same phase to the third branch 313, and outputs the first branch 311 and the second branch 312 to the fourth branch 314. The input is synthesized in reverse phase and output.
[0024]
Therefore, in the case of the zero mode operation, since the inputs of the first branch 311 and the second branch 312 are in phase, they are synthesized and output to the third branch 313 and are not output to the fourth branch 314. In the case of π mode operation, since the inputs of the first branch 311 and the second branch 312 are in reverse phase, they are synthesized and output to the fourth branch 314 and are not output to the third branch 313.
[0025]
In this case, an output window W1 having an opening area and thickness matched with the operating frequency f1 is provided in the third branch 313 for extracting the output of the zero mode operation, and the fourth branch 314 for extracting the output of the π mode operation. Further, if an output window W2 having an opening area and thickness matched with the operating frequency f2 is provided, the output of each mode operation can be taken out efficiently. In this case, in FIG. 1, the broadband characteristic required for the output window 18 provided in the output waveguide 17 portion becomes unnecessary.
[0026]
According to the above-described configuration, a multi-cavity klystron apparatus that operates at two different frequencies can be realized without reducing gain and operating efficiency.
[0027]
In the above embodiment, the case where two electron beams are used has been described. However, the present invention can use three or more electron beams. In this case, cavities arranged at the same position along each electron beam are coupled to each other through the coupling port. Further, in this case, a multi-cavity klystron apparatus having an operation mode with cavities coupled by three or more is obtained. Further, when the number of generated electron beams is increased, the voltage applied to the electron gun can be lowered when the same output is obtained, and the power source can be reduced in size accordingly. In the present invention, since a tuner is not used for the cavity portion or the like, it is possible to easily cope with an increase in output. Further, the intermediate cavity does not need to be plural, and can be constituted by one.
[0028]
【The invention's effect】
According to the present invention, it is possible to realize a multi-cavity klystron apparatus that operates at a plurality of different frequencies without degrading gain and operating efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic structural diagram for explaining an embodiment of the present invention.
FIG. 2 is a schematic structural diagram showing a part of a cavity according to the present invention, and a characteristic diagram for explaining an electric field distribution in the cavity portion.
FIG. 3 is a schematic structural diagram for explaining another embodiment of the present invention.
FIG. 4 is a schematic structural diagram showing a conventional example.
FIG. 5 is a schematic structural diagram showing a part of a cavity of a conventional example, and a characteristic diagram for explaining an electric field distribution in the cavity.
[Explanation of symbols]
11A, 11B ... Electron guns 12A, 12B ... Input cavities 13A, 13B ... Intermediate cavities 14A, 14B ... Output cavities 15A, 15B ... Collector 16 ... Input coupling loop 17 ... Output waveguide 18 ... Output windows ea, eb ... Electron beams Da, Db ... Drift tube

Claims (2)

A plurality of electron guns each generating an electron beam, an input signal amplified by the interaction with the electron beam, and a plurality of input cavities provided for each electron beam and coupled to each other; A plurality of intermediate cavities located on the electron beam traveling side of each input cavity and connected to each other at least one for each electron beam, and for each electron beam on the electron beam traveling side of each of the intermediate cavities A multi-cavity klystron apparatus comprising a plurality of output cavities coupled to each other for extracting an amplified output signal and a collector for capturing the electron beam , wherein the plurality of output cavities are first output cavities. A first branch connected to a first output waveguide coupled to the first output cavity, and coupled to the second output cavity. A second branch to which a two-output waveguide is connected; a signal that is input to the first branch; a signal that is input to the second branch; a third branch that is combined in phase; a signal that is input to the first branch; A magic T having a fourth branch in which a signal input to the second branch is synthesized in reverse phase, and an output window provided in each of the third branch and the fourth branch and matched to different frequencies. A multi-cavity klystron device . The multi-cavity klystron apparatus according to claim 1 , wherein an input cavity, an intermediate cavity, and an output cavity provided for each electron beam are arranged at the same position in the tube axis direction .

Images