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