Introduction to the twocavity klystron amplifier technical articles. Draw and explain the working of two cavity klystron amplifier. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. It is a narrow band device due to use of resonant cavities. Twocavity klystron amplifier 62801 circuit and wiring. An electronic oscillator can also be made from a klystron tube when the second cavity resonator is fed. It is given the name reflex klystron because of its reflex action of electron beam. Klystron multi cavity klystron, reflex klystron, working.
Find powerpoint presentations and slides using the power of, find free presentations research about two cavity reflex klystron ppt. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Important question and answers on reflex klystron with. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. The e3712 pulsed klystron is available with peak output power of 80 mw or 100 mw operating at 2,856 mhz. The klystron was invented at stanford university in 1937 and originally used as the oscillator in radar receivers during world war ii.
However, with the addition of intermediate cavities and other physical modifications, the basic two cavity klystron may be converted into a multicavity power klystron, capable of both highgain and highpower output. The first difference is that and two cavity klystron there are two cavities, whereas in reflex klystron there is only one cavity which access both buncher cavity and catcher cavity. The function of modules such as electron gun, magnet, collector is same as used in klystron described below. Other articles where twocavity klystron is discussed. Thus basically klystron amplifiers possess less power than their counterparts magnetron and travelling wave tube.
It is possible to produce oscillations in a klystron device which has only one cavity, through which electrons pass twice. This velocity modulation permits bunching of electrons while propagation. Interaction in klystron occurs only at the gaps of resonant cavities. Since the invention of the klystron in 1937, many different types and designs have been developed. Lowfrequency klystron for accelerator applications. A klystron oscillator has an input cavity resonant in a tm 010 mode and a larger output cavity resonant in a tm ono mode where n is an integer greater than 1, preferably equal to 2. Reflex klystron amplifier electronics club microwave. Klystrons are the most efficient of linear beam microwave tubes. Dhanalakshmi college of engineering department of ece. The operation of reflex klystron is a little bit different from the two cavity klystron because there is only one cavity. What is the principle of operation of a multicavity klystron. In order to achieve higher overall gain, one way is to connect several two cavity tubes in cascade, feeding the output to each of. Klystron amplifiers are used in a variety of industries, including satellite systems, television broadcasting, radar, particle accelerators, and in the. And the another difference is that in two cavity klystron at this place there is a collector which is used to collect the electron beam coming from the output.
All electrons injected from the cathode arrive at the first cavity with uniform velocity. Thus two cavity klystron amplifier utilizes the kinetic energy of moving electron beam for signal amplification. There are two cavities known as buncher and catcher cavity. The principle of velocityvariation, first used in heil oscillators, was also used in other microwave amplifying and oscillating tubes. This single cavity is work like a buncher as well as catcher cavity. Those electrons passing the first cavity gap at zeros of the gap voltage o r signal voltage pass through with. Pdf a two stage oscillator consisting of two coupled three cavity klystrons is studied. Let us understand twt and klystron basics before we look into comparison between the two. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. The most basic configuration is the two cavity klystron. Now understand the concept of reflex klystron in microwave engineering in details through following questions and answers.
The input cavity, with reentrant bosses defining a buncher gap, projects into the output cavity to form one of two reentrant bosses thereof defining a catcher gap. View and download powerpoint presentations on two cavity reflex klystron ppt. Z239 klystron two cavity klystron klystron reflex cv2187 two cavity resonator cavity resonator text. Two cavity klystron as the name implies, this klystron uses two cavities.
This name is given by the name of its inventor robert sutton, it allow the passage of electron beam through a single resonant cavity. An electron beam is formed in an electron gun and passed through the gaps associated with the two cavities fig. The simplest klystron tube is the two cavity klystron. A novel feature of this design is a cavity which is simultaneously excited at two frequencies. Microwave engineering cavity klystron tutorialspoint. The two cavity amplifier klystron is readily turned into an oscillator klystron by providing a feedback loop between the input and output cavities. The major difference between klystron and twt is that klystron cavities are replaced by structure of helix shape in twt. Two cavity klystron amplifiers working, amplification and. 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.
First of all, consider an electron a which passes through the resonator. The electron beam, accelerated by a positive potential, is constrained to travel through a cylindrical drift tube in a straight path by an axial magnetic field. Pdf the effect of space charge on bunching in a two. A klystron amplifier uses different cavities which control the electric field around the axis of the tube. A klystron tube makes use of speedcontrolled streams of electrons that pass through a resonating cavity. It is widely used microwave amplifier operated by principles of velocity and current modulation. The two cavity klystron is a widely used microwave amplifier operated by the principles of velocity and density modulation. These include the two cavity amplifier or oscilator, the reflex klystron, and the multicavity high power amplifier. Hello my name is rajbala, i am pursuing phd under the guidance of professor. Pdf lowfrequency klystron for accelerator applications. Reflex klystron oscillator operation application of. Electrons in a klystron are accelerated to a controlled speed by the application of several hundred volts.
Ece questions and answers on microwave engineering with explanation for various interview, competitive examination and entrance test. 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. The application for klystron with integral cavities is usually credited in the early 1939 to hahn and metcalf and to russell and sigurd varian, two brothers that. This is the reflex klystron oscillator, which will now be described. There is anode used to attract the electrons emitted from the cathode. The variation in the velocity of electrons while moving inside the tube is known as velocity modulation. 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. The two cavity klystron is the simplest klystron tube. The first cavity together with the coupling device is termed as a buncher. While passing through the first cavity, the electron beam is velocity modulated by the weak rf signal. The name of this klystron is taken due to its reflex act of electron beam. Assume that input signal is smaller than dc accelerating voltage. 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. A grid is placed in the middle of these cavities to allow the electrons to flow.
Due to this fact, usually it is used in the transmitter and not in the receiver. At a very high temperature, the cathode emits electrons. What is a klystron amplifier, types, differences and their. In this tube there are two microwave cavity resonators, the catcher and the buncher. The effect of space charge on bunching in a two cavity klystron. The klystron was the first embodiment of the velocity modulation principle. Simulation of a 95 ghz two stage three cavity klystron oscillator.
When installed, the tube projects through holes in the center of the cavity. In this video, i have explained velocity modulation process and two cavity klystron amplifier which works on the same principle. Klystron tube article about klystron tube by the free. It has two microwave cavity resonators the catcher and the buncher. The two cavity klystron in figure 27a and b may be used either as an oscillator or an amplifier. Difference between two cavity klystron and reflex klystron. The location is chosen because maximum energy transfer to the output catcher cavity occurs when the electrostatic field is of the correct polarity to slow down the electron bunches. This topic which is also called as tube devices is. The power gain of a two cavity klystron amplifier is about 30 db. The vacuum tube consists of a cathode, which is heated by a filament. The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118.
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