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