Klystron for high gradient accelerator research, in aip conf. It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. Photonic crystal reflex klystron using field emission. Proof of principle experiment on photonic crystal reflex. The essential elements of klystron are electron beams and cavity resonators. The electron gun emits the electron beam, which passes through the gap in the anode cavity. The twocavity klystron is a widely used microwave amplifier operated by the principles of velocity and density modulation. Pdf we investigated the foundations for highfrequency vacuum electron devices.
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. Jan 16, 2017 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. Microwave ovens, all about the magnetron, the educational. Typicallifetimesof8,000to15,000hourshavebeenreported. Introduction the 1939 was the epicenter of the golden period when principle of velocity modulation was evolved in order to overcome the transit time limitations of vacuum tubes. The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. Mar 24, 2016 working of reflex klystron oscillator. The reflex klystron amplifier is used as an oscillator in a modulator in microwave transmitters and radar receivers. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. The paramount o type tube is the two cavity klystron followed by the reflex klystron.
Their work was preceded by the description of velocity modulation by a. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. In order to achieve higher overall gain, one way is to connect several twocavity tubes in cascade, feeding the output to each of. Question bank department of electronics and communication.
Twystron is a hybrid amplifier which uses a combination of klystron and slow wave structures. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Classification of the klystrons, mode of operation of the twocavity, multicavity and. Lowpower klystrons are used as oscillators in terrestrial microwave relay. As a result, low power microwave oscillator called reflex oscillator, a trade mark of. During the first week you will operate a reflex klystron which will be the source of.
What is the principle of operation of a multicavity klystron. Klystron types there are two basic configurations of klystron tubes 1. In a reflex klystron, a small modulation of the repeller voltage is more often employed to fix the emitted frequency to that of a microwave resonator by a phase locking loop technique. Oscillators,in this video we will learn generation of microwave frequencies using reflex klystron oscillator. Moreover it uses repeller inplace of catcher cavity. The whole set up is as shown in the following figure. The operation of reflex klystron is understood by some assumptions. The twocavity klystron has mechanical tuning, but the reflex. F input signal to the buncher cavity with the help of loop coupling. How reflex klystron works electrical engineering stack exchange. Klystron vs magnetrondifference between klystron,magnetron.
Obtain relation between repeller voltage and frequency of operation of reflex klystron oscillator 6. Single reentrant cavity as a resonator the electron beam. Now understand the concept of reflex klystron in microwave engineering in details through following questions and answers. The reflex klystron is also called as sutton tube invented by robert sutton. It had its beginnings in europe and russia in the early 1930s. Reflex klystron oscillator rko, starting current of rko i. Microwave engineering ece questions and answers page 6. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity.
Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Experiment4 study of the characteristics of the klystron tube. Reflex klystron is one of the most commonly used microwave low power. These reflex klystrons continued to occupy a significant position in the testing world, and by the mid80s, reflex klystrons were available up into the 100s of gigahertz. Klystron oscillator reflex klystron traveling wave tube magnetron.
What is the basic principle involved in microwave tubes. The klystron is used in television transmission, particle accelerators, and powerful radar, like that in the dew line which defended north america from attack. History the fundamental principle behind the klystron, velocity modulation, has an interesting history. For a proofof principle experiment, a 10 ghz reflex klystron adopting the photonic crystal and the field emission cathode was also analytically and numerically designed. The electron beam is accelerated towards the anode cavity. This is the reflex klystron oscillator, which will now be described. The microwaves flow into the waveguide, which transports them to the. The name klystron comes from the greek verb klyzo referring to the action of waves breaking against a shore, and the suffix. Applegate diagram for the reflex klystron oscillator. Buncher cavity is the input cavity at which the electrons are bunched and the catcher cavity is the output cavity at which the output is taken but in reflex klystron only one cavity is present where the bunching process as well as output taken. Klystron multi cavity klystron, reflex klystron, working. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity but here the similarity ends. Reflex klystron is one of the most commonly used microwave low power generators.
Pdf experimental investigations on miniaturized highfrequency. In klystron strong electrostatic fields are required for its operation efficiently. A collector is present at the end to collect the electrons. Klystron works on the principle of velocity modulation of electrons. Reflex klystron telecommunications engineering mechanics. What is probably the primary advantage of the reflex klystron over the twocavity klystron is the mechanism used to tune the device.
A reflex klystron is an obsolete type in which the electron beam was reflected back along its path by a high potential electrode, used as an oscillator. This connection must have a defined delay so that the. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Klystron, including the reflex and multicavity klystron. 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.
I was an aetm3c in the navy and also remember those local oscillators. To study the characteristics of the reflex klystron tube and to determine its electronic tuning. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. The bunches of electrons excite microwaves in the output cavity of the klystron. The main difference between two cavity reflex klystron amplifier. In the reflex klystron, the electron beam passes through a single resonant cavity. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. Explain with the help of neat diagram, the working principle, construction and applications of multicavity klystron amplifier. The reflex klystron also known as a sutton tube after one of its inventors, robert sutton was a low power klystron tube with a single cavity, which functioned as an oscillator.
In this tube, electrons emitted from the heated cathode travel through the cavity grids toward the repeller plate, then are repelled and returned back the way they came, magnetron tubes. Understandexplain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. The power gain of a two cavity klystron amplifier is about 30 db. Other articles where twocavity klystron is discussed. A reflex klystron is an obsolete type in which the electron beam was reflected back along its path by a. Slow wave structures are also otype but have nonresonant periodic structures for electron interactions. A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies klystron types there are two basic configurations of klystron tubes 1.
To study the characteristics of the reflex klystron tube and to determine the its electronic. Wafer application of reflex klystron bendix reflex klystron vacuum tube bendix ka band klystron klystron tube ka band reflex klystron text. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies. It covers basics of klystron and magnetron and mention difference between them. Reflex klystron used as a lowpower microwave oscillator 2. When switch on the circuit, the electrons starts emitting from the cathode. The klystron was the first embodiment of the velocity modulation principle.
These electrons move at a uniform speed towards the anode until they are attracted by it. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. Microwave engineering cavity klystron tutorialspoint. Klystron oscillator reflex klystron traveling wave tube magnetron klystron. The electrons are fired into one end of the tube by an electron gun. This page on klystron vs magnetron describes difference between klystron and magnetron. The schematic diagram of a reflex klystron tube is shown in fig. Cavity grids and repeller are plane and parallel, and also very large in extent. Sketch output power and frequency of klystron versus repeller voltage for reflex klystron. This hole is exactly located in the center of broad wall because the. Reflex klystron working, oscillator and applegate diagram. Important question and answers on reflex klystron with.
The reflex klystron makes use of velocity modulation to transform a continuous electron beam into. Electrons are not intercepted by the cavity anode grid. Electron beams are produced from a source and the cavity klystrons are employed to amplify the signals. In chapter 2, we talk about microwave vacuum devices, their theory of operation and applications. Multi cavity klystron two cavity klystron used as lowpower. The reflex klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29.
Reflex klystron the analysis of a reflex klystron is similar to that of a twocavity klystron to some extent and is subjected to the following approximations. Pdf fundamentals of microwave electronics researchgate. The basics how capacitors work working principle duration. Working the first grid next to the cathode controls the number of electrons in the electron beam and focuses the beam. 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. Microwave engineering reflex klystron tutorialspoint. Reflex klystron article about reflex klystron by the free. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. Principle of operations the electron beam is injected into a first buncher cavity.
Intensive work, however, has led to products that offer higher output powers and extended operating lifetime, while retaining the benefits inherent in tetrode devices. Obtain electronic efficiency from twocavity klystron. Sep 27, 2017 in this video, i have explained reflex klystron with following points 1. Buncher cavity is the input cavity at which the electrons are bunched and the catcher cavity is the output cavity at which the output is taken but in reflex klystron only one cavity is present where. An electronic oscillator can also be made from a klystron tube when the second cavity resonator is fed back to the first one with a coaxial cable or waveguide. It is a low power tube with a single and work as an oscillator. Reflex klystron amplifier, microwave klystron amplifier slideshare. Yes, they had a bellows that was externally adjusted to cause the separation between grids that coupled to a resonant chamber as reflex. The conventional vacuum tubes, such as triodes, tetrodes, and pentodes, are still used as signal sources of low output. What is the difference between the two cavity klystron.
Oct 01, 2014 microwave linearbeam tubes 0 type 90 introduction we turn now to a quantitative and qualitative analysis of several conventional vac uum tubes and microwave tubes in common use. Frequency extension source modules to extend signal generator capability from 50 to 325 ghz. The passthrough effect, therefore, contributes to the overall operating efficiency of the transmitter. Reflex klystron amplifier used in microwave systems for generating higher. Product description a small hole in the broad wall of the waveguide is provided, through which output coupling pin of klystron tube enters into the waveguide. Diagram3 working principle 2, construction2, any 2 applications 1 marks each typically power gain of two cavity klystron is 30db.
Why is pulse modulation required in reflex klystron. Draw the equivalent circuit diagram of a reflex klystron. Explain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. But, these devices are replaced by semiconductor microwave devices. It was used as a local oscillator in some radar receivers and a modulator in microwave transmitters the 1950s and 1960s, but is now obsolete, replaced by semiconductor microwave devices. Reflex klystron oscillator operation application of. The voltage accelerates the dc electron beam to a high.
A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Difference between two cavity and reflex klystron two cavity klystron reflex klystron can act as both amplifier and. 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. After passing through the resonant cavity they are reflected by a negatively charged reflector electrode for another pass through the cavity, where they are then collected. Reflex klystron is also known as a sutton klystron. Microwave engineering ece questions and answers this is the electronics and communication engineering questions and answers section on microwave communication with explanation for various interview, competitive examination and entrance test.
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