View and download powerpoint presentations on two cavity reflex klystron ppt. It is known by this name due to its reflex action of electron beam. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. Microwave engineering ece questions and answers page 2.
The simplest klystron tube is the twocavity klystron. A sutton tube, or reflex klystron, is a type of vacuum tube used to generate microwaves. 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. The space between cathode and anode is called interaction space. Explain with suitable sketch the operation of two cavity klystron amplifier. Understandexplain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. From each mode and the band of frequencies over which the circuit can be tuned. It was used as a local oscillator in some radar receivers and a modulator in microwave transmitters the 1950s and 60s, but is now obsolete, replaced by semiconductor microwave devices. This is the reflex klystron oscillator, which will now be described. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. The brothers russell and sigurd varian of stanford university are the. Webster 2 generalized this analysis for the two cavity klystron by including space charge. This resonant cavity is used to velocitymodulate the electron beam and is very similar to the buncher and catcher cavities in the two cavity klystron. We will not yet observe waves, but this step is important in its own right.
At the time, klystrons were mostly two cavity or reflex oscillators. Klystron oscillator reflex klystron traveling wave tube biological effect of microwaves. The losses due to circuit factors can be reduced by a judicious use of the microwave. Pdf the results of timedomain numerical simulation of a fourcavity klystron oscillator with external delayed feedback using a 1. Coupled oscillators 1 two masses to get to waves from oscillators, we have to start coupling them together. At a very high temperature, the cathode emits electrons. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. Both are peak values, so, consequently, for the two cavity klystron. Reflexive klystron was used like oscillator, not classical klystron with 2 or more resonators, all thought that is possible to achieve if you put phase shifter between output and input, but effectiveness is poor. Microwave engineering cavity klystron tutorialspoint. Microwave engineering imp qusts pdf file mw important questions please find the attached pdf file of microwave engineering important questions bank. Today we take a small, but significant, step towards wave motion. Question bank department of electronics and communication. The step is the coupling together of two oscillators via a spring that is attached to both oscillating objects.
The general construction of the reflex klystron oscillator and a two. The conditions of maximum efficiency and the value of this efficiency for two cavity and three cavity klystrons were analyzed by feenberg 1 by means of the kinematic approximation. The twocavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. To make an oscillator, the output cavity can be coupled to the input cavity s with a coaxial cable or waveguide.
This type of klystron oscillator is called a reflex klystron because of the reflex action of. Oscillators pdf file oscillators pdf file oscillators pdf file download. Microwave engineering reflex klystron tutorialspoint. In the limit of a large number of coupled oscillators, we will. Klystron oscillators are most often used in the frequency range of a. Explain with suitable sketch the operation of twocavity klystron amplifier. Feb 18, 2016 two cavity klystron amplifiers working, amplification and applegate diagram by engineering funda duration. However, a twocavity klystron oscillator is inappropriate in the structure, because, when the oscillation frequency is varied, the resonant frequency of each cavity. Klystron is a vacuum tube used for the amplification and generation of microwave signal operation. We will discuss only about sinusoidal oscillators in this tutorial. There are two cavities known as buncher and catcher cavity. There is anode used to attract the electrons emitted from the cathode.
In this video, i have explained reflex klystron with following points 1. Two coupled oscillators normal modes overview and motivation. Jul 31, 2018 technical article introduction to the two cavity klystron amplifier july 31, 2018 by mark mitchell klystron amplifiers are used in a variety of industries, including satellite systems, television broadcasting, radar, particle accelerators, and in the medical field. In this tube there are two microwave cavity resonators, the catcher and the buncher. When an output cavity, tuned to the signal frequency, is placed in the. Design a klystron size is determined by the size of the bunching cavities.
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. In klystron amplifiers, they are there are multiple cavities, in klystron amplifiers there are multiple cavities. The following figure depicts an example of multi cavity klystron amplifier. The two amplifiers operate in switch mode, switching fully on or. Since, we have discussed travelling wave tube amplifiers and multi cavity klystron amplifiers, so let us compare these two. 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 reflex klystron contains a reflector plate, referred to as the. The complex dynamics of a model double cavity delayed feedback klystron oscillator is considered. Department of electronics and communication subject microwave engineeringeec 603 unitiii 1.
Find powerpoint presentations and slides using the power of, find free presentations research about two cavity reflex klystron ppt. 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 selfoscillation and stationary oscillation conditions are analyzed theoretically. The oscillator consists of two closedloop floatingdrifttube klystrons with the output cavity. Thus, the aspirants can practice the microwave engineering ece mcq online test to learn the microwave engineering ece questions and answers. The cavity is designed with six outer flat surfaces for mounting heaters and other additional components. The two cavity klystron is a widely used microwave amplifier operated by the principles of velocity and density modulation. The advent of linearbeam tubes began with the heil oscillators i in 1935 and the varian brothers klystron amplifier 1 in 1939. Klystron multi cavity klystron, reflex klystron, working. Two cavity klystron amplifier in the two chamber klystron, the electron beam is injected into a resonant cavity.
This leads us to the magnetron which is high power oscillator, but also it is not coherent. These oscillators work on a different principle to sine wave oscillators. List the two broad classifications of oscillators wave generators. Pdf timedomain picmodeling of the multiple cavity klystron. Reflex klystron is also known as a sutton klystron. The results of computer simulation of a two stage millimeterwave klystron oscillator are reported. Pdf simulation of a 95 ghz twostage threecavity klystron oscillator. Klystrons chapter microwave and rf vacuum electronic.
Positive feedback excites spontaneous oscillations at the resonant frequency of the cavities. Difference bw magnetron oscillator and klystron oscillator. In this design the oscillation is created by the physical shape of the anode, rather than external circuits or fields. Microwave communication questions and answers pdf free download for ece mcqs objective type interview questions lab viva manual gate cat syllabus. Lowpower klystrons are used as oscillators in terrestrial microwave relay. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. October 27, 2017 january 22, 2020 creatives at backward wave oscillators, multi cavity klystron, multi cavity magnetron, power and efficiency, traveling wave tube twt klystrons are also constructed with additional cavities between the bunches and catcher cavities. The parameters of a two cavity klystron amplifier are. Jan 07, 2019 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. The klystron was the first embodiment of the velocity modulation principle. It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. Pdf mutual synchronization of two coupled klystron.
Reflex klystron working, oscillator and applegate diagram. 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. The anode has several cavities that open into interaction space. Pdf computer simulation of a twostage millimeter wave. Aug 30, 2016 ms purva sharma, assistant professor, biyani girls college explained about two cavity klystron. All the multiple choice questions which are provided in the microwave engineering ece quiz are essential for the competitive examinations. Two cavity klystron amplifiers working, amplification. Reflex klystron is a microwave device that works on principle of velocity modulation in addition to current modulation. Loss in a slowwave structure backward wave oscillator.
Amplification of such two cavity klystron is low and hence multi cavity klystrons are used. The main frequency controlling element in the reflex klystron is the resonant cavity which forms part of the bunchercatcher. Such oscillators can provide output at frequencies ranging from 0 hz to 20 mhz. Of the two endcaps, one has two semirigid coaxial cables with coupling loops that slide into the open bore and provide rf coupling to the air cavity. 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. Reflex klystron oscillator operation application of. The great advance in magnetron design was the resonant cavity magnetron or electronresonance magnetron, which works on entirely different principles. The reflex klystron oscillator in which the electron beam passes twice. 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. Reflex klystron oscillators low power klystron tube with a single cavity, which functioned as an oscillator. A reflex klystron is an obsolete type in which the electron beam was reflected back along its path by a high potential electrode.
The first cavity together with the first coupling device is. 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. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. We present the results of numerical simulation of synchronization of two coupled delayedfeedback sband klystron oscillators. Jun 02, 2014 i am reading two cavity klystrons but not able to understand at all. The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. Our amplifiers feature excellent phase stability, pulse fidelity and low spurious signal levels.
This voltage accelerates the dc electron beam to a high velocity before injecting it into the grids of. Both are peak values, so consequently for the two cavity klystron. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. 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. Microwave engineering imp qusts mw important questions. A gunn oscillator is comprised of two major components. With the signal applied in the first cavity, we get weak bunches in the second cavity. Introduction to the twocavity klystron amplifier technical.
Certain features of waves, such as resonance and normal modes, can be understood with a. Other articles where twocavity klystron is discussed. Firstly, as we know that klystrons are used as amplifiers for microwave frequency and conventional vaccum tubes cant be used due to interelectrode capacitance and lead. By lowering the qs of the cavities and by introducing intermediate cavities, wider bandwidth operation can be achieved. Klystrons are velocitymodulated tubes that are used in radar and communications equipment as oscillators and amplifiers. A small fraction of the ultrahighfrequency oscillatory power generated in the second resonator is transmitted through a coupling slot to the first resonator in order to modulate electron velocities. In gunn oscillators, the gunn diode will be placed in a resonant cavity. A small number of industrially manufactured klystrons are continuousmode klystron oscillators, usually with two cavity resonators see figure l,b. Important question and answers on reflex klystron with. In the middle of these cavities, there is a grid allowing the electrons to pass.
Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Nonsinusoidal oscillators the oscillators that produce an output having a square, rectangular or sawtooth waveform are called nonsinusoidal or relaxation oscillators. Parametric amplifiers two cavity klystron amplifier. The frequency of operation of a klystron is set by the sizes of the input and output cavities. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. The physical components of a two cavity klystron consist of an electron emitter, two resonant cavities, a solenoid magnetic circuit to focuses the electron beam, and a collector depression structure. The vacuum tube consists of a cathode, which is heated by a filament. Oct 01, 2014 0type tube is the twocavity klystron, and it is followed by the reflex klystron.
Coates 200720 the actual value of m depends on how effectively the two inductors are magnetically coupled, which among other factors depends on the spacing between the inductors, the number of turns on. The velocities of electrons emitted from the cathode are modulated to produce a densitymodulated electron beam. Principles of twocavity klystrons twocavity klystron geometry. It is a lowpower device used primarily for two purposes. A repeller klystron is better suited for such cases. For this article, however, we will focus on another popular type. Pdf complex dynamics of a doublecavity delayed feedback. Z239 klystron two cavity klystron klystron reflex cv2187 two cavity resonator cavity resonator text. A smallsignal theory of this oscillator is developed. Electronic oscillators lc types are designed reflex klystron such a way that a small amount of energy is fed back into the tuned circuit at the correct time phase. They produce a square wave or pulsed output and generally use two amplifiers, and a frequency control network that simply produces a timing delay between two actions. The klystron amplifier can be used as an microwave oscillator or amplifier at low and high frequencies. Pdf a twostage oscillator consisting of two coupled three cavity klystrons is studied. Reflex klystron oscillators, modes and efficiency considerations.
By mechanically compressing the cavity, the volume of the cavity and the spacing of the grids connected to it are caused to change and. What are the high frequency limitations of conventional tubes. Signal source in mw generator ii local oscillators in receivers iii it is used in fm oscillator in low power mw links. If the instantaneous rf potentials on the two sides of a magnetron cavity are of opposite polarity, the operation is in the. In this video, i have explained two cavity klystron amplifier with following points 1. These will set up a field in the third cavity, which produces more concentrated bunches and. The simplest klystron tube is the two cavity klystron.
A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. The control grid in the reflex klystron controls the number of electrons, and the first grid in the cavity acts as an. One major type is the reflex klystron, which is used primarily as an oscillator. The k 300 klystron has been designed for use as the local oscillator in a. Klystron tube article about klystron tube by the free. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Klystron oscillators are most often used in the frequency. A klystron uses special cavities which modulate the electric field around the axis the tube. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. Klystron article about klystron by the free dictionary. 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. One cavity connected to wave guide through coaxial for output. A klystron is a vacuum tube that can be used either as a generator or as an amplifier or as an oscillator, at microwave frequencies. They perform a similiar funciton as reflex klystron oscillators.
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