The entire drifttube assembly, the three cavities, and the collector plate of the three cavity klystron are operated at ground potential for. Ppt klystron powerpoint presentation free to view id. In order to investigate how the efficiency of the 5ghz 500kw cw klystron prototype could be enhanced, the cavity design study is being carried out with simulation code based on the. When used as an amplifier, the weak microwave signal to be amplified is applied to the buncher cavity through a coaxial cable or waveguide, and the amplified signal is extracted from the catcher cavity. Furthermore, some analytical expressions are derived, such as the bunching formula of. An improved bandwidth has been obtained from a sixcavity pulsed sband klystron amplifier by the use of a doubletuned output circuit. The drift length of a twocavity klystron amplifier for highest power gain is onequarter of the reduced spacecharge wavelength. Although each beamlet carries small amount of current, the total current can be large. The basic electrode arrangement of a reflex klystron is given below. Since all intermediate cavities in a multicavity klystron operate in the same manner, a. The twocavity klystron uses what cavity as an output cavity. Tow pillbox windows with wr650 waveguide were chosen for power transmission.
Primary design of extended interaction klystron with multi. A twocavity klystron without a feedback path will operate as what type of circuit. Klystron vs magnetrondifference between klystron,magnetron. Comparison has been made with the results in normal triode operation and has shown a good agreement. A klystron in which there is at least one cavity between the input and output cavities, each of which remodulates the beam so that electrons are more.
It is known by this name due to its reflex action of electron beam. The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. Multicavity klystron amplifiers nippon electric co. The klystron was the first embodiment of the velocity modulation principle. It also utilizes a collector element at the end of the electron stream. In a permanent magnetic focusing device for guiding long electron beams in multicavity klystrons by means of spatially periodic or quasiperiodic magnetic fields, according to the invention the magnetic fields are produced by magnet rings or magnet spoked wheels magnetized in the radial direction and arranged one behind the other in the axial. Resonant cavity accelerators consist of several resonant cavities in series energized by a single sband klystron using a microwave power distribution system 25. Multicavity klystron october 27, 2017 january 22, 2020 creatives at backward wave oscillators, multicavity klystron, multicavity magnetron, power and efficiency, traveling wave tube twt klystrons are also constructed with additional cavities between the bunches and catcher cavities.
Letter increasing the bandwidth of an extended interaction. The mechanism of the beamwave synchronization and the coupling in the multi. In a multicavity klystron amplifier of the class comprising an electron gun for emitting an electron beam, an input cavity, a plurality of intermediate cavities, and a output cavity, said cavities being sequentially disposed along a path of said electron beam in the order mentioned, drift tubes respectively disposed between adjacent cavities, and a collector electrode. The multicavity power klystron klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and. Microwave engineering cavity klystron tutorialspoint. The two cavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. What is a klystron amplifier, types, differences and their. Under these limited conditions, we designed the klystrons based on a multi cell output cavity to improve the powerconversion efficiency significatly. Multicavity klystron october 27, 2017 january 22, 2020 creatives at backward wave oscillators, multicavity klystron, multi cavity magnetron, power and efficiency, traveling wave tube twt klystrons are also constructed with additional cavities between the bunches and catcher cavities. However, the german military considered the frequency drift of hollmans device to be undesirable, and based their radar systems on the klystron instead. These will set up a field in the third cavity, which produces more concentrated bunches and. Factors influencing the design of multicavity klystrons. At a very high temperature, the cathode emits electrons.
Multiple output cavities in sheet beam klystron us8547006b1 en 20100212. Comsol conference 2015 grenoble multiphysics design of a klystron buncher. Since all intermediate cavities in a multicavity klystron operate in the. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids.
The 2nd harmonic cavity was employed as the 3rd cavity to satisfy the phase sensitivity requirement due to the change in the beam voltage. The klystron with internal or external feedback built in its design can function as oscillator. These types of cavity klystron amplifiers include various cavities used for controlling the electric field in the region of the axis of the klystron tube. Jlc klystron specifications a multibeam klystron mbk 3 can be another solution to jlc klystron. Some of the factors which must be considered in the design of a multicavity klystron are examined. These lengths are obtained from an extrapolation of the twocavity klystron by regarding the multicavity klystron as a. The bunches of electrons excite microwaves in the output cavity of the klystron.
Due to the number of the resonant cavities, klystrons are divided up into twocavity klystrons, multicavity klystrons, and repeller klystrons. One very important item that is required for highpower klystron amplifier operation is an axial magnetic field a magnetic field parallel to the axis of the klystron. Rqis the cavitys characteristic impedance which is only related with the cavitys shape. Due to the number of the resonant cavities, klystrons are divided up into two cavity klystrons, multi cavity klystrons, and repeller klystrons. The microwaves flow into the waveguide, which transports them to the accelerator. On the other hand, klystrons are narrowband devices, compared with travellingwave tubes. The same method has been applied to tuning measurement of a diode pulsed klystron, e3712. Stability analysis of cband 500kw klystron with multicell. A three cavity klystron is illustrated in figure 28.
A klystron in which there is at least one cavity between the input and output cavities, each of which remodulates the beam so that electrons are more closely bunched. Stability analysis of cband 500kw klystron with multi. On the optimization of the drift lengths of staggertuned. Construction a reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. Request pdf highpower fourcavity sband multiplebeam klystron design we develop a methodology for the design of multiplecavity klystron interaction circuits. The vacuum tube consists of a cathode, which is heated by a filament. Klystron power supply skps610 multi meter klystron mount xm251 isolator xi621 variable attenuator xa520 frequency meter xf455 detector mount xd451 vswr meter sw115 cro theory. The perturbation theory multicavity largeorbit gyroklystron. Colour online the trend of the amplitude of the rf current in the multigap cavity. The newly developed klystrons should have the same specifications, including perveance and overall length, to replace existing ones. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output.
Amplification of such two cavity klystron is low and hence multi cavity klystrons are used. The mechanism of the beamwave synchronization and the coupling in the multigap cavity at 225 ghz are studied in detail by. This paper represents the design of multibeam sixtybeam electron gun and focusing system for high power, compact klystron. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. The simplest klystron tube is the two cavity klystron. Electron gun for a multiple beam klystron with magnetic compression of the electron beams. Introduction to the twocavity klystron amplifier technical.
Since all intermediate cavities in a multicavity klystron operate in the same manner, a representative three cavity klystron will be discussed. The limitations on the lowlevel bandwidth obtainable imposed by the effects of the couplings. The presently accepted values for these optimum drift lengths for a multicavity klystron amplifier are also onequarter of. Other articles where twocavity klystron is discussed. By using this theory in every cavity, a recurrence formula about the azimuthal velocity of electron is obtained, which considers the prebunching function of every cavity. Klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and output cavities of the basic klystron.
The main difference between two cavity reflex klystron amplifier. A reflex klystron consists of an electron gun, a cavity with a pair of grids and a repeller plate as shown in the above diagram. The electron beam and cavities should be designed so as to maximize a figure of meritthe product of the voltage gain and the bandwidth of one stage of the amplifier. Another system consists of a single vhf cavity energized by a triode tube that is less expensive than klystron. The simulations show that the efficiency is close to.
A collection of theoretical analyses is presented for rf cavities, intense electron beams, beamcavity interactions, and smallsignal klystron bunching. In a multi cavity klystron amplifier of the class comprising an electron gun for emitting an electron beam, an input cavity, a plurality of intermediate cavities, and a output cavity, said cavities being sequentially disposed along a path of said electron beam in the order mentioned, drift tubes respectively disposed between adjacent cavities, and a collector electrode. A klystron has one or more special cavities around the axis of the tube that modulate the electric field. With the signal applied in the first cavity, we get weak bunches in the second cavity. Design of a highefficiency sband klystron with a multi. The following figure depicts an example of multi cavity klystron amplifier. Vidyalankar group of educational institutes 947 views 8.
A coaxial magnetron uses a different architecture and has better stability. However, with the addition of intermediate cavities and other physical modifications, the basic twocavity klystron may be converted into a multicavity power klystron, capable of both highgain and highpower output. The beam voltage is 4 kv with a total beam current of 5 8. In order to investigate how the efficiency of the 5ghz 500kw cw klystron prototype could be enhanced, the cavity design study is being carried out with.
In a multicavity klystron amplifier of the class comprising an electron gun for emitting an electron beam, an input cavity, a plurality of intermediate cavities, and a output cavity, said cavities being sequentially disposed along a path of said electron beam in the order mentioned, drift tubes respectively disposed between adjacent cavities, and a collector. Highpower fourcavity sband multiplebeam klystron design. Amplification of such twocavity klystron is low and hence multicavity klystrons are used. From the space limitation, a lowheight waveguide was coupled to an output cavity. A free powerpoint ppt presentation displayed as a flash slide show on id. Jul 31, 2018 the two cavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Design of a highefficiency sband klystron with a multicell. The multidefect structures described above allow a sufficient outcoupling, but at high frequencies the design becomes a very tight compromise between interbeam spacing, rq, qext, and frequency separation. The gain of klystron amplifiers can be very high more than 60. Vidyalankar group of educational institutes 947 views. Diploma sem v two cavity klystron amplifier microwave and radar lecture vidyalankar duration. Klystron multi cavity klystron, reflex klystron, working.
There are two cavities known as buncher and catcher cavity. Under these limited conditions, we designed the klystrons based on a multicell output cavity to improve the powerconversion efficiency significatly. The cavity is integrated with a carbon nanotube cold cathode in order to reduce thermal expansion and cooled by an opportune airflow that regulates the temperature distribution to compensate the resonant frequency shift. The following figure depicts an example of multicavity klystron amplifier. In klystron amplifiers, which are physi cally long, it is difficult to keep the electron beam properly formed during its travel through the rf section. Multicavity klystron article about multicavity klystron. The paper presents an application of perturbation theory to multicavity largeorbit gyroklystron. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity. The heater boils off electrons when heated and the electrons are ejected from the cathode and accelerate towards the anode due to the high dc potential. These intermediate cavities produce further bunching. In this tube there are two microwave cavity resonators, the catcher and the buncher. Finally, we present a feasibility discussion of using this multidefect pc structure to construct an integrated klystronaccelerator cavity, along with numerical results showing a peak. The dimensions of the resonant cavities of the multiplebeam klystron are determined in such a way as to enable functioning in the tm 0n mode na whole number greater than 1 and drift tubes relative to the beams go through the klystron cavities at places where the electrical field, in the cavities, is at its maximum value. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation.
A network is arranged in the hub of multi cavities to let the flow of electrons. A multi cavity klystron amplifier according to claim 1 wherein said output cavity comprises an electroconductive cylinder, electroconductive end plates connected to the opposite ends of said cylinder and provided with axial openings for passing said electron beam, drift tubes secured to the inner sides of said end plates, tuning means electrically connected to one side wall of said cylinder. Development of a 500 mw, onemicrosecond, multikiloampere. The multicell cavity can provide the higher power and the wider bandwidth, however there. The principle of velocityvariation, first used in heil oscillators, was also used in other microwave amplifying and oscillating tubes. Unlike a klystron, a magnetron is not a coherent transmission source, but has a. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope. Tuning measurement of multicavity klystrons in diode mode. The klystron amplifier comprises an input cavity a plurality of intermediate cavities and an output cavity which are arranged along the path of an electron beam for focusing it, and an output waveguide coupled to the output cavity through a coupling opening. The multi cell cavity can provide the higher power and the wider bandwidth, however there is a possibility to generate the self. Other articles where two cavity klystron is discussed. It was known that a multi cavity resonant magnetron had been developed and patented in 1935 by hans hollmann in berlin.
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