General principles of microwave tubes beam loading admittance radial gapcoupling coefficient. Klystron for high gradient accelerator research, in aip conf. The modulator stability system for the bepcii klystron. The electron beam is modulated as it was in the other types of klystrons by passing it through an oscillating resonant cavity but here the similarity ends. To understand the operation of a reflex klystron i think you need to start with a basic understanding of a tuned circuit made up from a capacitor c and inductor l. Introduction the 1939 was the epicenter of the golden period when principle of velocity modulation was evolved in order to overcome the transit time limitations of vacuum tubes. The name klystron comes from the greek verb klyzo referring to the action of waves breaking against a shore, and the suffix. Twystron is a hybrid amplifier which uses a combination of klystron and slow wave structures. It is a low power tube with a single and work as an oscillator. These include generic diode, schotty diode, shockley diode, constantcurrent diode, zener diode, light emitting diode, photodiode, tunnel diode, varactor, vacuum tube, laser diode, pin diode, peltier diode, gunn diode, and so on. Microwave power tubes span a wide range of applications, operating at frequencies from 300 mhz to 300 ghz with output powers from a few hundred watts to more than 10 mw. The voltage stability of the bepcii modulator demanded is less than 0. These tubes are used for amplification,oscillation,switching and other applications. A selection of waveguide components the power supply for the microwave source.
Reflex klystron free download as powerpoint presentation. Klystron microwave test bench5 the microwave test benches are precision made microwave systems, which use standard type rectangular waveguide components to illustrate the essential elements of this field for study. Klystron types presentday klystrons fall into three categories. Moreover it uses repeller inplace of catcher cavity. Klystrons are linear tube in which the magnetic field is applied to focus the electron and the electric field is applied to drift the electron. Klystron oscillator reflex klystron traveling wave tube magnetron. Microwave engineering ece questions and answers page 6. But,in case of magnetron both the electric and magnetic fields are perpendicular. Reflex klystron oscillator operation application of. This page covers microwave tubes which include klystron,magnetron and traveling wave tubetwt. Due to the large number of klystron units, even a low failure rate of each component could increase the load of maintenance work and limit availability of the facility. The reflex klystron is also called as sutton tube invented by robert sutton.
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. These electrons move at a uniform speed towards the anode until they are attracted by it. After passing through the resonant cavity they are reflected by a negatively charged reflector electrode for another pass through the cavity, where they are then collected. But, these devices are replaced by semiconductor microwave devices. Performance evaluation of klystron beam focusingsystem with. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. An electron gun focusses an electron beam with the velocity of light. In klystron strong electrostatic fields are required for its operation efficiently. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. Applications range from the familiar to the exotic. Other articles where twocavity klystron is discussed. Slacpub16466 increasing klystron efficiency using com and. A klystron looks and works something like an organ pipe. When switch on the circuit, the electrons starts emitting from the cathode.
Blowing into the organ pipe produces a flow of air. Klystron types there are two basic configurations of klystron tubes 1. Explain the bunching process of a twocavity klystron and derive. Klystron is a microwave generator compare slacs large, highpower microwave generator klystron below with this much smaller one magnetron right from a typical microwave oven. Microwave test benches microwave test bench manufacturer. Travelling wave tube is a cylindrical structure which contains an electron gun from a cathode tube. Their work was preceded by the description of velocity modulation by a. Microwave tubes and circuits from the book electronic communication systems by george kennedy. Normally we use separate components in devices such as radio transmitters and receivers but as frequencies increase the two components merge into one structure and become a. The electronic tuning range of the reflex klystron is usually referred to as the variation in frequency between half power pointsthe points in the oscillating mode where the power output is half the maximum output in the mode.
This time, however, the reference electron is taken as one that passes the gap on its way to the repeller at the time when the gap voltage is zero and going negative. Before outlining its history, it is useful to sketch out the operating principles of the device. The reflex klystron makes use of velocity modulation to transform a continuous electron beam into. Mar 24, 2016 microwave frequencies are millimeter waves so we need to generate them through amplifiers or oscillators,in this video we will learn generation of microwave. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. 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. Let a beam of electrons, which has been accelerated by a. Reflex klystron used as a lowpower microwave oscillator 2. On a special case, this article discuss about gunn. Klystron power supply, klystron tube, isolator, frequency meter, variable attenuator, detector mount, waveguide stand, vswr meter and bnc cable. Klystron vs magnetrondifference between klystron,magnetron. For drfs, the reliability of klystron itself is estimated to be fairly high because of its relativelylow output power 800 kw per klystron.
The operation of reflex klystron is understood by some assumptions. Microwave ovens, all about the magnetron, the educational. Since all intermediate cavities in a multicavity klystron operate in the same manner, a. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. For the electron beam generation, carbon nanotube cathode is. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Operation the klystron was the first embodiment of the velocity modulation principle.
A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies. Reflex klystron article about reflex klystron by the free. The klystron was the first embodiment of the velocity modulation principle. Avalanche diode construction, working and its applications. F input signal to the buncher cavity with the help of loop coupling. Experiment4 study of the characteristics of the klystron tube. Microwave tubes klystron,magnetron,twt traveling wave tube. An avalanche diode is a one kind of diode that is designed to experience an avalanche breakdown at a particular reverse bias voltage. The modulator stability system for the bepcii klystron li shen, yun long chi, qun ming dai, xing wang yang, ihep, beijing 49, china abstract the stability of the modulator high voltage output pulse is very important for a klystron. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. Multi cavity klystron two cavity klystron used as lowpower. 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. 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.
Slow wave structures are also otype but have nonresonant periodic structures for electron interactions. The electron beam is accelerated towards the anode cavity. The bunches of electrons excite microwaves in the output cavity of the klystron. The klystron is a device for amplifying microwave frequency signals that achieve high levels of power gain by applying vacuum tube principles and the concept of electron bunching. Modern semiconductor technology has effectively replaced the reflex klystron in most applications. Proof of principle experiment on photonic crystal reflex. The passthrough effect, therefore, contributes to the overall operating efficiency of the transmitter. Explain the operation principle of the cavity klystron with neat sketch. Although the design is robust, the bac principles discussed above have been applied to achieve an even more efficient design. Klystron modes measurement of klystron characteristics. The reflex klystron amplifier is used as an oscillator in a modulator in microwave transmitters and radar receivers.
The basics how capacitors work working principle duration. This article discusses about a brief information about the construction and working of an avalanche diode. What is the principle of operation of a multicavity klystron. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. Reflex klystron or repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Basic klystron rf power input rf drive rf power output energy modulation d v z,0, i 0 v z,0, i 1 modulate decelerate v c e z e z. 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.
The diodes are classified into different types based on their working principles and characteristics. The main difference between two cavity reflex klystron amplifier. This page on klystron vs magnetron describes difference between klystron and magnetron. 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. A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies klystron types there are two basic configurations of klystron tubes 1. As with the multicavity klystron, the operating mechanism is best understood by considering the behavior of individual electrons. It covers basics of klystron and magnetron and mention difference between them.
Klystron multi cavity klystron, reflex klystron, working. What is the difference between the two cavity klystron. Typicallifetimesof8,000to15,000hourshavebeenreported. This is the multiple choice questions in chapter 11. Reflex klystron is a microwave device that works on principle of velocity modulation in addition to current modulation. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. Sep 27, 2017 in this video, i have explained reflex klystron with following points 1. The 5045 klystron design has remained largely unchanged over the last couple decades.
The electrons are fired into one end of the tube by an electron gun. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Series attempts to cover the basic principles underlying the operation of klystrons and planar grid tubes as oscillators and amplifiers. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Reflex klystron working, oscillator and applegate diagram. The reflex klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. In this tube, electrons emitted from the heated cathode travel through the cavity grids toward the repeller plate, then are repelled and returned back the way they came, magnetron tubes. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Klystron oscillator reflex klystron traveling wave tube magnetron klystron. Lowpower klystrons are used as oscillators in terrestrial microwave relay. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity. The twocavity klystron has mechanical tuning, but the reflex. A singlecavity klystron in which the electron beam is reflected back through the cavity resonator by a repelling electrode having a negative voltage. Before the invention of transistors, vacuum tubes are used for electronic circuit design.
In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron. The new design improves the klystron efficiency from 45% to 55% by adding 4 cavities to the drift section figure 4. Klystrons are used in satellite systems, television broadcast, and radar, as well as particle accelerators and medicine. The velocities of electrons emitted from the cathode are modulated to produce a densitymodulated electron beam. The microwaves flow into the waveguide, which transports them to the. The electron gun emits the electron beam, which passes through the gap in the anode cavity. 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. The reflex klystron is mostly used as a microwave oscillator.
Comsol conference 2015 grenoble multiphysics design of a klystron buncher the analysis follows a multiphysics model approach, in order to prevent alterations of the electromagnetic em behavior, while exposing the device to these multiple physics factors. Rf input is sent to one end of the helix and the output is drawn from the other end of the helix. In the reflex klystron, the electron beam passes through a single resonant cavity. Klystron and microwave department capabilities and xband. Reflex klystron vacuum tube manufactured goods free 30. Reflex klystron which is used as a low power microwave oscillator. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. How reflex klystron works electrical engineering stack exchange. Why is pulse modulation required in reflex klystron. The klystron was the first embodiment of the velocity.
Microwave engineering reflex klystron tutorialspoint. As a result, low power microwave oscillator called reflex oscillator, a. Klystron works on the principle of velocity modulation of electrons. Reflex klystron oscillator rko, starting current of rko i. Connect the detector output to y input and sawtooth output of the klystron of power supply to xinput of scope fig. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. 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. Important question and answers on reflex klystron with. Here a photonic crystal resonator with tm 330 mode is employed in a reflex klystron for xband proofof principle experiment. What is probably the primary advantage of the reflex klystron over the twocavity klystron is the mechanism used to tune the device. Microwave engineering cavity klystron tutorialspoint. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons.