Caryotakis, performance of a 150mw sband klystron, aip conf. The effect of space charge on bunching in a two cavity klystron. Klystron is a vacuum tube used for the amplification and generation of microwave signal operation. The losses due to circuit factors can be reduced by a judicious use of the microwave. The essential elements of klystron are electron beams and cavity resonators. 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. A collector is present at the end to collect the electrons. Reflex klystron is a microwave device that works on principle of velocity modulation in addition to current modulation. Because the bandwidth of the buncher section could be increased by stagger tuning 1, the output cavity was seen as the bandwidthlimiting element of the klystron design. Complex dynamics of a two cavity klystron oscillator with delayed feedback.
Diode drive cavity idler cavities output cavity collector guidefield solenoid. In addition to the intermediate cavities, there are several physical differences between the basic two cavity klystron and the multicavity klystron. Z2391g cv2187 the z2391g is a reflex klystron developed for use as a frequency modulated transmitter and capable of delivering an output of approximately one watt. A two cavity klystron uses two resonant cavities around the axis of the tube which modulates the electric field.
Jan 07, 2019 reflex klystron pdf posted on january 7, 2019 by admin 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. Next, select file from aj disks menu, and from within the file menu select open. Cavity test has demonstrated the use of high power rf vector modulators to control multiple rf cavities driven by a single high power klystron to accelerate a nonrelativistic beam. Klystron tube article about klystron tube by the free. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. All the multiple choice questions which are provided in the microwave engineering ece quiz are essential for the competitive examinations. Z239 klystron two cavity klystron klystron reflex cv2187 two cavity resonator cavity resonator text. In order to achieve higher overall gain, one way is to connect several two cavity tubes in cascade, feeding the output to each of. Microwave engineering imp qusts pdf file mw important questions please find the attached pdf file of microwave engineering important questions bank. Reflex klystron is also known as a sutton klystron. Between the cavities around the glass envelope a magnet is used in order to keep the electron beam in the center and in concentrated form at the end inside the glass envelope. The sixcavity test demonstrated acceleration of beam with. Multicavity power klystrons repeller klystron two cavity klystron. Let us understand twt and klystron basics before we look into comparison between the two.
On july 21, 1937, russ varian entered in his journal the sketch of a twocavity oscillator, and the. A two cavity klystron amplifier has the following parameters. Klystron tube two cavity klystron amplifier for very highpower applications, such as synchrotrons and radar systems, have since been developed. In this tube there are two microwave cavity resonators, the catcher and the buncher. The main difference between two cavity reflex klystron amplifier. Microwave engineering imp qusts mw important questions. Klausst 72fvm 36betwixt 22 reflex klystron, volker muehlhaus 21asdf44 the process is referred to as modulation. With the signal applied in the first cavity, we get weak bunches in the second cavity. The reflex klystron uses a singlecavity resonator to modulate the rf beam and. Klystron multi cavity klystron, reflex klystron, working. Two forms of such a device, also called linear beam klystron, are given in the following figure. There are two cavities known as buncher and catcher cavity.
Klystron tube two cavity klystron amplifier for very highpower applications, such as. Both modes of resonance of the output were used in an overlapping mode. Reflex klystron oscillator operation application of. These will set up a field in the third cavity, which produces more concentrated bunches and. The two cavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. An experimental investigation of a twocavity klystron operating. The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. Oct 03, 2016 two cavity klystron amplifiers working. It is known by this name due to its reflex action of electron beam. In the output cavity, signals are amplified by bunched electrons. 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.
Interaction in klystron occurs only at the gaps of resonant cavities. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. It is given the name reflex klystron because of its reflex action of electron beam. The configuration shown in the figure is correct for oscillator operation. Klystron versus repeller voltage for reflex klystron. 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. Velocity modulation process in two cavity klystrons microwave linear beam tubes o type duration. Derive an expression for the efficiency of the klystron amplifier. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope. The velocities of electrons emitted from the cathode are modulated to produce a densitymodulated electron beam. At a very high temperature, the cathode emits electrons. The klystron was invented at stanford university in 1937 and originally used as the oscillator in radar receivers during world war ii.
It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. A sutton tube, or reflex klystron, is a type of vacuum tube used to generate microwaves. 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 frequency is primarily determined by the dimension of resonant cavity. Pdf a twostage oscillator consisting of two coupled three cavity klystrons is studied. The simplest klystron tube is the two cavity klystron. Microwave engineering cavity klystron tutorialspoint. Difference between two cavity klystron and reflex klystron. A klystron tube makes use of speedcontrolled streams of electrons that pass through a resonating cavity. Pdf complex dynamics of a twocavity klystron oscillator. The brothers russell and sigurd varian of stanford university are the. The feedback path provides energy of the proper delay and phase relationship to sustain oscillations.
A microwave source of surprising range and endurance pdf. The vacuum tube consists of a cathode, which is heated by a filament. 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. The general construction of the reflex klystron oscillator and a two. The basic two cavity klystron klystrons are velocitymodulated tubes that are used in radar and communications equipment as oscillators and amplifiers. Jul 31, 2018 the two cavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. Because of the high q of the cavities, the signal quickly becomes a sine wave at the resonant frequency of the cavities.
Electrons in a klystron are accelerated to a controlled speed by the application of several hundred volts. It is given the name reflex klystron because of its. This is the reflex klystron oscillator, which will now be described. The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. Multicavity klystron two cavity klystron amplifier principle velocity modulated tube high velocity electron beam is generated by an electron gun and sent down along a gas tube through an input cavity buncher, drift space field free and an output cavity catcher to a collector electrode anode. Oct 01, 2014 0type tube is the twocavity klystron, and it is followed by the reflex klystron.
Question bank department of electronics and communication. This tube used a two cavity extended interaction output section the rcco. Multiple cavity klystron a source of chaotic microwave. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. Download scientific diagram schematic diagram of a two cavity klystron amplifier. The ranges of all these voltages are given in the specification data sheet. There is anode used to attract the electrons emitted from the cathode. Klystron tube 2k25 the klystron tube 2k25 is a single cavity variable frequency microwave generator of low power and low efficiency. Electron beams are produced from a source and the cavity klystrons are employed to amplify the signals. The two cavity klystron in figure 27 may be used either as an oscillator or an amplifier. Installation of 6 cavities in the existing hins beamline has been completed and beam measurements have been made.
As shown electron beam is generated by electron gun which passes through the space between input cavity i. The rf signal to be amplified is coupled to input cavity. Understandformulate the expression for optimum drift space distance l optimum in a two cavity klystron amplifier. P2 shows the relationship between output power, frequency and reflector voltage. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. Remembera reflex klystron operates at 8 ghz with dc beam voltage 300 v, repeller space1mm for 1 mode. Review of highpower microwave source research this. 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. It also utilizes a collector element at the end of the electron stream. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. In this article, well learn about the twocavity klystrons unique build and the concept of electron bunching. The power gain of a two cavity klystron amplifier is about 30 db.
Description of special versions of modern klystron tubes. The first cavity together with the first coupling device is. Pdf the effect of space charge on bunching in a two. Due to the number of the resonant cavities klystrons are divided up into. Let a beam of electrons, which has been accelerated by a. 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 next post we will see the variant of two cavity klystron called reflex klystron posted by unknown at 09. In the middle of these cavities, there is a grid allowing the electrons to pass. It has two microwave cavity resonators the catcher and the buncher. The helix travelingwave tube twt, the coupled cavity twt, the forwardwave am plifier fwa, and the backwardwave amplifier and oscillator bwa and bwo are also 0type tubes, but they have nonresonant periodic structures for electron inter actions. A klystron uses special cavities which modulate the electric field around the axis the tube. The first cavity together with the coupling device is termed as a buncher. The function of modules such as electron gun, magnet, collector is same as used in klystron described below.
Classification of the klystrons, mode of operation of the twocavity, multicavity and reflex klystrons. An experimental 2cavity klystron with a variable drift space has been constructed to investigate velocitymodulated electron beams. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. Thus, the aspirants can practice the microwave engineering ece mcq online test to learn the microwave engineering ece questions and answers. The reflex klystron contains a reflector plate, referred to as the. The klystron amplifier can be used as an microwave oscillator or amplifier at low and high frequencies. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. The whole set up is as shown in the following figure. The helix travelingwave tube twt, the coupledcavity twt, the forwardwave am plifier fwa, and the backwardwave amplifier and oscillator bwa and bwo are also 0type tubes, but they have nonresonant periodic structures for electron inter actions. Due to the number of the resonant cavities klystrons are divided up into two or multicavity klystrons, and reflex or repeller klystrons. It is a lowpower device used primarily for two purposes. A 500 kw lband klystron with broad bandwidth for sub. Draw the equivalent circuit diagram of a reflex klystron. Among sources of chaotic microwave radiation, a delayed feedback multiple cavity klystron oscillator is one of the most promising due to high power level and high efficiency.
A klystron amplifier uses different cavities which control the electric field around the axis of the tube. Microwave engineering reflex klystron tutorialspoint. Introduction to the twocavity klystron amplifier technical. Other articles where twocavity klystron is discussed. A klystron uses one or more special cavities, which modulate the electric field around the axis the tube. The signal will initiate an electromagnetic field inside the cavity. A grid is placed in the middle of these cavities to allow the electrons to flow. A three cavity klystron is illustrated in figure 28. Aug 30, 2016 ms purva sharma, assistant professor, biyani girls college explained about two cavity klystron. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. Reflex klystron reduced power from the bunches, in reflex klystron, reduces the reflex klystron of the cavity oscillations and causes a decrease in output power. Design and simulation of cavity and rf section for. Microwave engineering ece questions and answers page 2.
The first cavity with the first coupling device is called the buncher, while the second cavity with. This was achieved by developing a resonant coupled cavity output rcco section to increase the bandwidth of the output cavity of the klystron. The simplest klystron tube is the twocavity klystron. What is the difference between the two cavity klystron.
Request pdf multiple cavity klystron a source of chaotic microwave radiation a number of applications, such as charged particle accelerators, microwave plasma heating and modem communication. A smallsignal theory of this oscillator is developed. What is the principle of operation of a multicavity klystron. Important question and answers on reflex klystron with.
Two cavity klystron amplifier 2 cavity klystron amplifier works on the following principles. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. The following figure depicts an example of multi cavity klystron amplifier. State the characteristics and applications of the two cavity. Obtain electronic efficiency from two cavity klystron. Pdf simulation of a 95 ghz twostage threecavity klystron oscillator. The klystron was the first embodiment of the velocity modulation principle. The major difference between klystron and twt is that klystron cavities are replaced by structure of helix shape in twt. I think u1 may have to do with getting the reflex klystron started.
A 500 kw lband klystron with broad bandwidth for subharmonic. The two cavity klystron in figure 27a and b may be used either as an oscillator or an amplifier. The cathode of the multicavity power klystron must be larger to be capable of emitting large numbers of elec trons. Since all intermediate cavities in a multicavity klystron operate in the same manner, a representative three cavity klystron will be discussed. Introduction to the twocavity klystron amplifier technical articles.
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