Microwave engineering reflex klystron tutorialspoint. In fact, according to kek injector operating statistics during 10 years in 2000s, the failures in focusing solenoids were the most frequent reasons to exchange klystron assemblies among the other. The klystron is a linearbeam device that overcomes the transittime limitations of a gridcontrolled tube by accelerating an electron stream to a high velocity before it is modulated. The electron beam emitted from the cathode is accelerated by the grid. Lowpower klystrons are used as oscillators in terrestrial microwave relay. Since all intermediate cavities in a multicavity klystron operate in the same manner, a. The essential elements of klystron are electron beams and cavity resonators.
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. Voltages required for operation of reflex klystron tube such as beam, heater and reflector voltage. Sprehn, rettig, peebles and luhmann, of ucla, described experiments in phase locking a 280 ghz backwardwave oscillator and a 140 ghz reflex klystron to a 35 ghz reference. Multi cavity klystron two cavity klystronused as lowpower. The optical klystron is a modificatio n of the undulato r which can be used to improve the gain in a free electro n laser.
The frequency is primarily determined by the dimension of resonant cavity. In this tube there are two microwave cavity resonators, the catcher and the buncher. The most impressive power achieve ments at very good efficiencies continue to occur in the gyrotron area. The simplest klystron tube is the twocavity klystron. The klystron was the first embodiment of the velocity modulation principle. Chin kek, 11 oho, tsukubashi, ibarakiken, 305, japan abstract we have developed a new method for a realistic and more accurate simulation of klystron using the magic code. The microwaves flow into the waveguide, which transports them to the accelerator. Klystron mount manufacturer, klystron mount supplier in. Reflex klystron used as a lowpower microwave oscillator 2.
Hence, by changing the volume of resonator, mechanical tuning range ofklystron is possible. The electrons are originally accelerated to high velocity by a potential of several hundred volts and enter a narrow gap that forms part of a cavity resonator system see. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. Modern semiconductor technology has effectively replaced the reflex klystron in most applications. Multi cavity klystron used as lowpower microwave amplifier reflex klystron reflex klystron reflex klystron single reentrant cavity as a resonator. Multi cavity klystron two cavity klystron used as lowpower. It was found that the switching characteristics were strongly dependent on. P2 shows the relationship between output power, frequency and reflector voltage. The principle of velocityvariation, first used in heil oscillators, was also used in other microwave amplifying and oscillating tubes. To understand the operation of a reflex klystron i think you need to start with a basic understanding of a tuned circuit made up from a capacitor c and inductor l. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. The electron gun emits the electron beam, which passes through the gap in the anode cavity. When the beam of electrons reflect back to the grid due to the repeller voltage in reflector plate,how the grid decelerates the returning electrons and how they release their energy to the grid.
If you need an oscillator, a reflex tube will work fine, but it is old school technology. Microwave engineering cavity klystron tutorialspoint. Klystron usually will have two or more cavities as per gain and bandwidth requirements needed for different applications. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Switching was accomplished by applying a pulse to the repeller of the passive klystron. The electrons are originally accelerated to high velocity by a potential of several hundred volts and enter a narrow gap that forms part of a cavity resonator system see figure, where they are acted upon by a radiofrequency field, which causes a bunchingup effect. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical engineers russell and sigurd varian, which is used as an amplifier for high radio frequencies, from uhf up into the microwave range. After the focusing electrodes there is a cavity resonator which encircles the glass envelope. Reflex klystron article about reflex klystron by the free.
Series attempts to cover the basic principles underlying the operation of klystrons and planar grid tubes as oscillators and amplifiers. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. A small hole located exactly at the center of the broad wall of the waveguide is used to put the coupling pin of the tube as the electric field vector of em energy is maximum at the center only. Reflex klystron working free download as powerpoint presentation. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids.
For the love of physics walter lewin may 16, 2011 duration. Let a beam of electrons, which has been accelerated by a. Klystron characteristics free download as word doc. Six ips were arranged vertically at 25cm distant from a typical klystron, determined by a tld measurement. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope. Klystron multi cavity klystron, reflex klystron, working. A klystron is characterized by high power, large size, high stability, high gain, and high operating voltages. It covers basics of klystron and magnetron and mention difference between them. The klystron power supply also provides all the other d. A reflex klystron is an obsolete type in which the electron beam was reflected back along its path by a high potential electrode. Normally we use separate components in devices such as radio transmitters and receivers but as frequencies increase the two components merge into one structure and become a. Klystrons with mw output power have been developed at cpi, slac, thales, and so on. Cw klystron amplifier is to acquire various experiences in the domestic design and parts fabrication of the mw grade klystron amplifier, which are essential in proper and efficient operation of high power rf system. Klystron types presentday klystrons fall into three categories.
Design study of rf section and cavities for cepc 650 mhz klystron. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical engineers russell and sigurd varian, which is used as an. Reflex klystron free download as powerpoint presentation. Highpower gyroklystrons for acceleration applications strathprints. Lowpower klystrons are used as oscillators in terrestrial microwave relay communications links, while highpower klystrons are used as output tubes in uhf television. Reflex klystron vacuum tube manufactured goods free 30.
The klystron beam focusing system is one of the key components in the whole system. First, you need to determine what your need for a klystron is. The brothers russell and sigurd varian of stanford university are the. This page on klystron vs magnetron describes difference between klystron and magnetron. The application for klystron with integral cavities is usually credited in the early 1939 to hahn and metcalf and to russell and sigurd varian, two brothers that.
Typicallifetimesof8,000to15,000hourshavebeenreported. Modulation is accomplished by varying the velocity of the beam, which. Operation klystrons amplify rf impinj speedway revolution. Klystron a power amplifier tube used to amplify weak microwave energy provided by a radio frequency exciter to a high power level for a radar transmitter. Jensen abstract this report deals with a method of modulating a reflex klystron whereby the message to be transmitted is modulated on a subcarrier, which in turn modulates the klystron through its repeller.
Microwave engineering reflex klystron this microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a. Spontaneou s emission and gain are theo retically studied as functio n of electron energy and wavelength. We are a trusted manufacturer, exporter, trader and supplier of klystron mount. The modulator consisted of an eplane tjunction that was terminated on the sidearm by a reflex klystron operating in the passive region. 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. In the process, the electrons give up their kinetic energy to the cavity rf fields. A loop coupling is used inside the cavity to get the output. Klystron vs magnetrondifference between klystron,magnetron. Keep, the ammod amplitude knob and amfre knob at the mid position. Several effects limiting the gain enhancement are calculate d. How reflex klystron works electrical engineering stack exchange.
In the a transmitter setup, a klystron produces 3 cm. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity. For the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons.
It consists of movable short at one end of the waveguide to direct the microwave energy generated by the klystron tube. The main difference between two cavity reflex klystron amplifier. Performance evaluation of klystron beam focusingsystem with. Klystron for high gradient accelerator research, in aip conf. Of the resulting frequency spectrum only a narrow band, which. Experiments were carried out to determine the characteristics of a reflectiontype modulator. Reflex klystron article about reflex klystron by the. Slow wave structures are also otype but have nonresonant periodic structures for electron interactions. Klystrons are the most efficient of linear beam microwave tubes. The electronic tuning range of the reflex klystron is usually referred to as the variation in frequency between half power pointsthe points in the oscillating mode where the power output is half the maximum output in the mode. Note that in the spacecharge limited regime the power of the klystron rises as the 52 power of the voltage and the impedance that the. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. Performance evaluation of klystron beam focusingsystem.
There is a tuneable cavity which adjusts the position of the potential nodes and antinodes in the waveguide. All these components are enclosed in a glass envelope. Change the meter switch of klystron power supply to beam voltage position,and rotate the beam voltage knob clockwise up to 300 v deflections in meter. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. Measurements of xrays from the rf systems of the electron. Twystron is a hybrid amplifier which uses a combination of klystron and slow wave structures. Department of electronics and communication engineering ec 2405 optical and microwave lab manual vii sem ece 1 prepared by m. The modulator is the dc power supply for the klystron. As shown in the given diagram it is composed of heater, cathode, focusing electrodes and repeller anode. Klystron characteristics physical quantities electrical.
Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. On the klystron power supply, vswr meter and cooling fan. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. A moveable detector on the waveguide can detect the waveguide potential variations using a milliameter. 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. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. Oct 01, 2014 338 microwave linearbeam tubes 0 type chap. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. The paramount o type tube is the two cavity klystron followed by the reflex klystron. Some clas sical techniques such as using a low perveance, harmonic bunching 5 and a multibeam klystron 6 have been used in commercial klystrons. Gyroklystrons not only have the bunching in the axial direction, which is.
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