A reflex klystron is oscillating at the frequency of its resonant cavity. A range of four modes of operation are normally available. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. Feb 15, 2016 a klystron which is used as an amplifier for high radio frequencies, from uhf up into the microwave range. The klystron beam focusing system is one of the key components in the whole system. Diode semiconductor tunnel, gunn, impatt, varactor diodes, pin, lsa, schottky barrier diode. A singlecavity klystron in which the electron beam is reflected back through the cavity resonator by a repelling electrode having a negative voltage. Sep 27, 2017 in this video, i have explained reflex klystron with following points 1. Electrons in a klystron are accelerated to a controlled speed by the application of several hundred volts. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. 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. Turn the meter switch of power supply to beam voltage position and beam voltage at 300volt with the help of beam voltage knob. Optimization of micromachined reflex klystrons for operation at terahertz frequencies article pdf available in ieee transactions on microwave theory and techniques 5210.
May 02, 2020 microwave engineering lab viva question bank, engineering edurev notes is made by best teachers of. High performance modulator for 80mw klystron was designed and fabricated,good performance which the. The twocavity klystron is a widely used microwave amplifier operated by the principles of velocity and current. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. The electron beam emitted from the cathode is accelerated by the grid and passes through the cavity anode to the repeller space between the cavity anode and the repeller electrode. To operate continuously the test modulator for full operation, the. 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. Tetrodes and pentodes, high frequency effects in vacuum tubes, theory and application of two cavity klystron amplifier, reflex klystron oscillator, traveling wave tube amplifier.
High performance pulse modulater for 80mw sband klystron in. Also what is the type of oscillators used in mobile for producing microwaves. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into. The reflex klystron operates in a different mode for each additional cycle that the electrons remain in the repeller field. The essential elements of klystron are electron beams and cavity resonators. Moreover it uses repeller inplace of catcher cavity. The main difference between two cavity reflex klystron amplifier. 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. 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.
Modelling of micromachined klystrons for terahertz operation. Frequency extension source modules to extend signal generator capability from 50 to 325 ghz. This page on klystron vs magnetron describes difference between klystron and magnetron. The name klystron comes from the greek verb klyzo referring to the action of waves breaking against a shore, and the suffix. The electrons are fired into one end of the tube by an electron gun. Electron beams are produced from a source and the cavity klystrons are employed to amplify the signals.
Klystrons amplify rf signals by converting the kinetic energy in a dc electron beam into radio frequency power. Reflex klystron working free download as powerpoint presentation. The 5045 klystron design has remained largely unchanged over the last couple decades. Revathi klystron power supply reflex klystron isolator frequency meter attenuator directional coupler v. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Performance evaluation of klystron beam focusingsystem with. Other articles where twocavity klystron is discussed. As shown in the given diagram it is composed of heater, cathode, focusing electrodes and repeller anode. Draw the equivalent circuit diagram of a reflex klystron. 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. Optimization of micromachined reflex klystrons for operation at. During the first week you will operate a reflex klystron which will be the source of. In klystron strong electrostatic fields are required for its operation efficiently. Download scientific diagram schematic diagram of a twocavity klystron amplifier.
Its principle of operation is velocity and current modulation. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. In this video, i have explained reflex klystron with following points 1. Mode 1 is obtained when the repeller voltage produces an electron transit time of 34 cycle. Klystron an ultrahighfrequency electronic vacuum device in which a steady stream. Slow wave structures are also otype but have nonresonant periodic structures for electron interactions. The choice of mode is determined by the difference in power available from each mode and the band of frequencies over which the circuit can be tuned. Reflex klystron working, oscillator and applegate diagram. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. Reflex klystron download 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. The coarse frequency adjustment of a reflex klystron is accomplished by. The electron beam is accelerated towards the anode cavity. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable.
All these components are enclosed in a glass envelope. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope. At microwave frequencies, however, the transit time or angle is large compared to the period of the microwave signal, and the potential between the cathode and the. Klystron vs magnetrondifference between klystron,magnetron. Klystron types presentday klystrons fall into three categories. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. May 31, 2014 on the klystron power supply, vswr meter and cooling fan. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Since all intermediate cavities in a multicavity klystron operate in the same manner, a. Pls post the operation of reflex klystron and klystron tubes. A klystron tube makes use of speedcontrolled streams of electrons that pass through a resonating cavity. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Reflex klystron used as a lowpower microwave oscillator 2.
Which of the following operating frequencies is used for the modern loran navigational system. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. Set the variable attenuator at the maximum position a zero micrometer reading. Reflex klystron telecommunications engineering mechanics. Klystron for high gradient accelerator research, in aip conf. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source.
Twystron is a hybrid amplifier which uses a combination of klystron and slow wave structures. Tubes generate and amplify high levels of microwave power more cheaply than solid state devices. The actual mode used 1 34 cycles through 4 34 cycles, 2 34 cycles through 6 34 cycles, etc. Microwave engineering cavity klystron tutorialspoint. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. Operation the klystron was the first embodiment of the velocity modulation principle. 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. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. This is indeed the principal operation of such microwave tubes as klystrons and magnetrons. 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.
If you need an oscillator, a reflex tube will work fine, but it is old school technology. Set the modswitch of klystron power supply to cw position, beam voltage control knob to. Klystron multi cavity klystron, reflex klystron, working. Pure carrier wave operation and in external modulation facilities is also provided with the instrument for generalized use.
Observations freq ghz a1db a2db a3db a4db calculations. The klystron power supply also provides all the other d. Klystron tube article about klystron tube by the free. Microwave engineering reflex klystron tutorialspoint. Although the design is robust, the bac principles discussed above have been applied to achieve an even more efficient design. Multi cavity klystron used as lowpower microwave amplifier reflex klystron reflex klystron reflex klystron single reentrant cavity as a resonator. Coupling db a1 a3db directivity db a3 a4db isolation db a1 a4db insertion loss db a1 a2db prepared by m. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. Reflex klystron article about reflex klystron by the. Microwave communication questions and answers pdf free download. Ec6701 rf and microwave engineering syllabus regulation 20. A system of classification derived from the practice and method of collaboratively creating and managing tags to annotate and categorize content. Klystron works on the principle of velocity modulation of electrons.
A reflex klystron is a specialized low power vacuum tube used to produce oscillations at microwave frequency. If the reflector voltage is made slightly less negative, the. The klystron was invented at stanford university in 1937 and originally used as the oscillator in radar receivers during world war ii. Lowpower klystrons are used as oscillators in terrestrial microwave relay. The velocities of electrons emitted from the cathode are modulated to produce a densitymodulated electron beam. Klystrons are the most efficient of linear beam microwave tubes. The new design improves the klystron efficiency from 45% to 55% by adding 4 cavities to the drift section figure 4. Let us assume that a reference electron e r crosses the anode cavity but has no extra velocity and it repels back after reaching the repeller electrode, with the same velocity. After the focusing electrodes there is a cavity resonator which encircles the glass envelope. This hole is exactly located in the center of broad wall because the. Slacpub16466 increasing klystron efficiency using com and.
To study the mode characteristics of the reflex klystron tube and to determine its electronic tuning range. In the reflex klystron, the electron beam passes through a single resonant cavity. Obtain electronic efficiency from twocavity klystron. It covers basics of klystron and magnetron and mention difference between them. The brothers russell and sigurd varian of stanford university are the. Explain the principle of operation of magic tee and. For the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Free lecture notes pdf for rme subject rme 2 mark,16 mark with answers,rme parta,part. 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.
Oct 01, 2014 340 microwave linearbeam tubes 0 type chap. The passthrough effect, therefore, contributes to the overall operating efficiency of the transmitter. The power output is high in the first mode of operation of the reflex klystron. Klystron oscillator reflex klystron traveling wave tube magnetron. Design study of rf section and cavities for cepc 650 mhz 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. Reflex klystron oscillator 10 mechanism of operation a reflex klystron consists of an electron gun, an accelerating grid, a single reentrant cavity and a repeller plate youve reached the end of your free. 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. Reflex klystron vacuum tube manufactured goods free 30. Typicallifetimesof8,000to15,000hourshavebeenreported. Give the performance specification of reflex klystron. Description of special versions of modern klystron tubes. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Rf and microwave engineering ec6701 syllabus pdf free download.
The operation of reflex klystron is understood by some assumptions. Reflex klystron article about reflex klystron by the free. Connect the components and equipments as shown in the fig. Ec6701 rf and microwave engineering syllabus regulation 20 anna university free download. First, you need to determine what your need for a klystron is. Pdf optimization of micromachined reflex klystrons for. Klystrons are basically specialized tubes used as amplifiers and oscillators at microwave frequency range.
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