Ec 1403 microwave engineering 16 marks questions with. What is a klystron amplifier, types, differences and their. 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. Klystrons chapter microwave and rf vacuum electronic. 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. Ec 1403 microwave engineering 16 marks questions with answers. This amplifier is mainly used as an oscillator within a modulator of radar receivers as well as microwave transmitters. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Pdf optimization of micromachined reflex klystrons for operation. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Difference between two cavity and reflex klystron two cavity klystron reflex klystron can act as both amplifier and.
So, this is how oscillations are sustained in the reflex klystron by to and fro movement of electrons from cavity to repeller space. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. Reflex klystron is one of the most commonly used microwave low power generators. The reflex klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. It means that the high frequencies can be amplified by multi cavity klystron. I have a doubt on how exactly a reflex klystron worksas an rf source.
Microwave engineering directional couplers a directional coupler is a device that samples a small amount of microwave power for measurement purposes. A klystron size is determined by the size of the bunching cavities. Maharashtra state board of technical education autonomous. What changes occurs in the frequency due to the repeller voltage variation. Design and analysis of 5045 sband klystron dc electron gun. After the focusing electrodes there is a cavity resonator which encircles the glass envelope. Other articles where twocavity klystron is discussed. Bunching of electrons is clearly visible in the central region. The process can be repeated by including more cavities, until considerable amplification takes place, or until the increased space charge within the bunches prevents tighter bunching. What is the maximum theoretical efficiency, frequency range of the reflex klystron.
The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into. Following equation or formula is used for reflex klystron calculator. A method to achieve spatial bunching on the double frequency of the induced energy spread in an optical klystron is described. 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. A reflex klystron is an obsolete type in which the electron beam was reflected back. A microwave source of surprising range and endurance george caryotakis stanford linear accelerator center, stanford university, stanford ca 94309 abstract this year marks the 60th anniversary of the birth of the klystron at stanford university. 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. They are manufactured for operation in the decimeter, centimeter, and millimeter wave bands. Inspire your inbox sign up for daily fun facts about this day in history, updates, and special offers.
The conventional vacuum tubes, such as triodes, tetrodes, and pentodes, are. Explain the bunching process of a twocavity klystron and derive the expression for. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. The conventional vacuum tubes, such as triodes, tetrodes, and pentodes, are still used as signal sources of low output. The bunched electrons in a reflex klystron can deliver maximum power to the cavity at. Varian box 10 sperry gyroscope rhenium plating for klystron grids box 10 sperry gyroscope investigation of cycleweld process box 10 sperry gyroscope theory of modulation of reflex klystrons basic small signal theory box 10 graphical methods for analysis of velocity modulation bunching.
How are oscillations produced in a reflex klystron. The reflex klystron oscillator in which the electron beam passes twice. 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. What are the various modes of operation in the reflex klystron. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. The main difference between two cavity reflex klystron amplifier. From each mode and the band of frequencies over which the circuit can be. B derive an expression for the bunching parameter in the reflex klystron. Single reentrant cavity as a resonator the electron beam.
As shown in the given diagram it is composed of heater, cathode, focusing electrodes and repeller anode. Determine the amplification process in helix traveling wave tube twt. Application of multi cavity klystron this type of klystron is mostly used for the purpose of amplification of microwave length of frequencies. Full text of klystrons and microwave triodes see other formats. This process is called liga and is a combination of deepetch lithography and electroforming. Electrons which cross the gap within 90 of the bunch centre are retarded and give up energy to the field of the cavity.
Dhanalakshmi college of engineering department of ece ec6701 rf and microwave engineering unit 4 part a 1. D a reflex klystron has vo 2500 volt and frequency 6 ghz and drift space. Second order bunching in an optical klystron sciencedirect. The bunching parameters measure deviations of the multiplicity distribution from a poisson distribution. A reflex klystron achieves the same bunching by causing the beam to reverse. Pdf progress on a gridded electron gun for a sheet beam. Now understand the concept of reflex klystron in microwave engineering in details through following questions and answers.
However, these devices are substituted with semiconductor microwave devices. Explain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Bunching process bunching process is called phase focusing effect. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. The reflex klystron contains a reflector plate, referred to as the repeller. It is known by this name due to its reflex action of electron beam. The first papers on the theory of the reflex klystron were published by the soviet physicists ia. Microwave engineering ece questions and answers page 6. So, the design and manufacturing of electron gun is important in making a klystron.
This places an upper limit on the efficiency of the device. Construction and principle of operation, velocity modulation and bunching process applegate diagram. So, this is how electrons move in this reflex klystron tube. C explain the resonant modes and the process of electronic tuning in reflex klystron.
Electrons are not intercepted by the cavity anode grid. Reflex klystron calculator converters and calculators. It was the first working klystron that physicists and engineers there had been able to observe. Klystron amplifiers are used in a variety of industries, including satellite systems, television broadcasting, radar, particle accelerators, and in the medical field.
Following is the list of useful converters and calculators. The onedimensional klystron code, dmki, 2 was used to determine that the klystron would operate with about the. Experiment4 study of the characteristics of the klystron tube. Cavity grids and repeller are plane and parallel, and also very large in extent. 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. Which is impossible and not feasible to use other components for this purpose. Maharashtra state board of technical education autonomous isoiec 27001 2005 certified summer 16 examination subject code. In statistics as applied in particular in particle physics, when fluctuations of some observables are measured, it is convenient to transform the multiplicity distribution to the bunching parameters. Operative principles comsol conference 2015 grenoble multiphysics design of a klystron buncher dc beam from gun modulated beam.
Explain the bunching process of a twocavity klystron and derive the expression for bunching parameter. Criteria necessary to construct such a second order buncher and the phase space evolution are presented. The bunching parameters measure deviations of the multiplicity distribution from a poisson distribution, since for this distribution. Microwave engineering directional couplers tutorialspoint. Reflex klystron telecommunications engineering mechanics. Ec 1403 microwave engineering two marks questions with. From each mode and the band of frequencies over which the circuit can be tuned. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. Archived from the original pdf on september 24, 2015. Dhanalakshmi college of engineering department of ece. Explain in detail about 2cavity klystron amplifier. Reflex klystrons are the most widely used ultrahighfrequency device. 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 modulator is the dc power supply for the klystron.
Two cavity klystron is a amplifier where as reflex klystron is an oscillator. Reflex klystron is invented by robert sutton, so another name of this klystron amplifier is sutton tube. The initial bunching process should gather as many electrons as possible. Understandexplain the principle of operation of a reflex klystron oscillator and derive an expression for the bunching parameter. Ece questions and answers on microwave engineering with explanation for various interview, competitive examination and entrance test.
The power and spectra of the output signal are shown in figure 3, with the stability of the tube apparent, although there is a small ripple on the signal. The buncher needs to be critically matched to the rf source at the working frequency. Thermionic cathode is the most common electron gun4 in klystron since thermionic mode of emission of electrons is easy and inexpensive. Microwave engineering reflex klystron tutorialspoint. Reflex klystron free download as powerpoint presentation. A loop coupling is used inside the cavity to get the output. Velocity modulation is the process that causes the velocity modulated electron. The reflex version of the klystron, perfected at sperry and.
Klystron multi cavity klystron, reflex klystron, working. Characteristics of a reflectiontype microwave modulator. Lowpower klystrons, particularly reflex oscillators, lost the battle to solidstate. Klystrons article about klystrons by the free dictionary. Now, let us see bunching process and the modes and reflex klystron, this vertical axis represent the distance from the cavity gap towards the repeller plate, and this. All these components are enclosed in a glass envelope. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. The reflex klystron is a singlecavity klystron that overcomes the disadvantages of the. Lowpower klystrons are used as oscillators in terrestrial microwave relay communications links, while highpower klystrons are used as output tubes in uhf television. Determine the beam current density in multi cavity klystron amplifiers 11. High efficiency klystrons using the com bunching technique. This type of a klystron is called a reflex klystron because of the reflex action of the electron beam. What are the assumptions for calculation of rf power in reflex klystron.
Important question and answers on reflex klystron with. Now, let us see bunching process and the modes and reflex klystron, this vertical axis. If the antenna diameter is 3m and the receiver has a bandwidth of 2mhz with 10 db noise figure. The reflex klystron contains a reflector plate, referred to as the.
In this article, well learn about the twocavity klystron s unique build and the concept of electron bunching. In wikipedia it says that, the electrons are fired into one end of the tube by an electron gun. In the output catcher cavity, each bunch enters the cavity at the time in the cycle. Understand the velocity modulation process and power output in reflex klystron 12. Uncorrelated particle production leads to the poisson statistics, thus deviations of the bunching parameters from the poisson values mean correlations between particles and. Because of security restrictions, which had been imposed by sperry for industrial reasons and by the national defense research council, little was known about this new microwave tube. In the process, he invented the microwave cavity i.
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