The wavelength correspond to microwave frequency range is. There are few intermediate cavities used between buncher cavity and catcher cavity. The dimensions of the resonant cavities of the multiple beam klystron are determined in such a way as to enable functioning in the tm 0n mode na whole number greater than 1 and drift tubes relative to the beams go through the klystron cavities at places where the electrical field, in the cavities, is at its maximum value. Multiple beam klystron research at calabazas creek research. We introduce our work on designing two cavity singlebeam and multi beam klystrons. The electron beam emitted from the cathode k is accelerated by the grid g and passes through the cavity anode a to the repeller space between the cavity. 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. At a very high temperature, the cathode emits electrons. The magnetic field is only used to focalize the electron beam. View and download powerpoint presentations on two cavity reflex klystron ppt. 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. Other articles where twocavity klystron is discussed.
Due to the number of the resonant cavities, klystrons are divided up into two cavity klystrons, multi cavity klystrons, and repeller klystrons. The two cavity klystron is a widely used microwave amplifier operated by the principles of velocity and current modulation. The mechanism of the beamwave synchronization and the coupling in the multi gap cavity at 225 ghz are studied in detail by calculating the. The frequency of operation of a klystron is set by the sizes of the input and output cavities. A highefficiency multiple beam klystron mbk, designated the vkl8301, is being developed for the desy tera electron volt superconducting linear accelerator tesla in hamburg, germany. Design of a multi beam klystron cavity from its single. Multi beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3d code only. Philips also devised some multi reflex structures, see. Electrons in a klystron are accelerated to a controlled speed by the application of several hundred volts. What is a klystron amplifier, types, differences and their. The perturbation theory multicavity largeorbit gyroklystron. The same method has been applied to tuning measurement of a diode pulsed klystron. Some of the factors which must be considered in the design of a multi cavity klystron are examined.
Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Multicavity klystron amplifiers nippon electric co. Find powerpoint presentations and slides using the power of, find free presentations research about two cavity reflex klystron ppt. 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. Microwave engineering cavity klystron for the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. This makes it a great amplifier, but with a narrow bandwidth. An important advance was the multi cavity magnetron, first proposed in 1934 by a.
Klystron vs magnetrondifference between klystron,magnetron. Solved examples with detailed answer description, explanation are given and it would be easy to understand. Development of a 10mw, lband, multiplebeam klystron for. Klystron multi cavity klystron, reflex klystron, working. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. Motivations comsol conference 2015 grenoble multiphysics design of a klystron buncher. The velocities of electrons emitted from the cathode are modulated to produce a densitymodulated electron beam. Stability analysis of cband 500kw klystron with multicell. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. On the other hand, klystrons are narrowband devices, compared with travellingwave tubes.
By lowering the qs of the cavities and by introducing intermediate cavities, wider bandwidth operation can be achieved. Microwave engineering cavity klystron tutorialspoint. Experiment4 study of the characteristics of the klystron tube. These intermediate cavities produce further bunching which. It has been applied to the solenoidfocused kek xb72k no. With magic, a comprehensive, fullscale simulation of klystron from cathode to collector can be carried out, unlike other codes that are specialized for simulation of only parts of klystron.
The limitations on the lowlevel bandwidth obtainable imposed by the effects of the couplings between nonadjacent cavities can. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. This page on klystron vs magnetron describes difference between klystron and magnetron. However, the first truly successful example was developed by aleksereff and malearoff in ussr in 1936, which achieved 300 watts at 3 ghz 10 cm wavelength. By using this theory in every cavity, a recurrence formula about the azimuthal velocity of electron is obtained, which considers the prebunching function of every cavity. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity. Multiple choice questions 1 solution at the bottom. Design of a highefficiency sband klystron with a multicell. The gain of klystron amplifiers can be very high more than 60. Broadband and highpower terahertz radiation source based. The cavity should be free from mode contamination form them. A lowvoltage, multibeam radio frequency source that operates at a voltage less than or equal to approximately 2040 kv and that generates at least 600 kw at a pulse width of approximately 530 ms.
Multi cavity klystron october 27, 2017 april 2, 2018 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. 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. These electrons move at a uniform speed towards the anode until they are attracted by it. Under these limited conditions, we designed the klystrons based on a multi cell output cavity to improve the powerconversion efficiency significatly. The dimensions of the resonant cavities of the multiplebeam klystron are determined in such a way as to enable functioning in the tm 0n mode na whole number greater than 1 and drift tubes relative to the beams go through the klystron cavities at places where the electrical field, in the cavities, is at its maximum value. In the next post we will see the variant of two cavity klystron called reflex klystron. The rf source includes an electron gun having a cathode configured to generate a plurality of beamlets.
The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Factors influencing the design of multicavity klystrons. Microwave engineering ece questions and answers page 2. Abstract recently, there has been a rising international interest in multi beam klystrons mbk in the lband and sband, with active development taking place. 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.
The mechanism of the beamwave synchronization and the coupling in the multi gap cavity at 225 ghz are studied in detail by. A klystron in which there is at least one cavity between the input and output cavities, each of which remodulates the beam so that electrons are more. Tuning measurement of multicavity klystrons in diode mode. All electrons injected from the cathode arrive at the first cavity with uniform velocity. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Design and performance of lband and sband multibeam. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope.
The unequalwidth slots are the key design of the multiple gap cavity, and the influences of unequalwidth slots on the electromagnetic field distribution and beamwave interaction are. The newly developed klystrons should have the same specifications, including perveance and overall length, to replace existing ones. A radiofrequency interaction unit pole piece is arranged between a main magnetic field generator and an outputside magnetic field generator. These intermediate cavities produce further bunching. 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. The klystron was invented at stanford university in 1937 and originally used as the oscillator in radar receivers during world war ii. These mbks are developed by industries such as toshiba, thales and cpi. 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. In this tube there are two microwave cavity resonators, the catcher and the buncher. Some of the factors which must be considered in the design of a multicavity klystron are examined. The simplest klystron tube is the two cavity klystron. A network is arranged in the hub of multi cavities to let the flow of electrons. The main difference between two cavity reflex klystron amplifier. Above is an actual picture of two cavity klystron amplifier used for space communication purposesthus klystrons are very helpful at microwave frequencies as amplifiers and oscillators.
Comparison has been made with the results in normal triode operation and has shown a good agreement. The vacuum tube consists of a cathode, which is heated by a filament. The multi cell cavity can provide the higher power and the wider bandwidth, however there is a possibility to generate the self. The bunches of electrons excite microwaves in the output cavity of the klystron. Jlc klystron specifications a multi beam klystron mbk 3 can be another solution to jlc klystron. It is known by this name due to its reflex action of electron beam. From the space limitation, a lowheight waveguide was coupled to an output cavity. The basic electrode arrangement of a reflex klystron is given below. This embodiment results in highpowered klystrons capable at working. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Multicavity klystron article about multicavity klystron. These types of cavity klystron amplifiers include various cavities used for controlling the electric field in the region of the axis of the klystron tube. At 800mhz, the klystron only operates efficiently within a mhz or two. A klystron has one or more special cavities around the axis of the tube that modulate the electric field.
We introduce our work on designing twocavity singlebeam and multibeam klystrons. It covers basics of klystron and magnetron and mention difference between them. When switch on the circuit, the electrons starts emitting from the cathode. Furthermore, some analytical expressions are derived, such as the bunching formula of electrons, beamwave interaction power. Other articles where two cavity klystron is discussed. In a multi cavity klystron amplifier of the class comprising an electron gun for emitting an electron beam, an input cavity, a plurality of intermediate cavities, and a output cavity, said cavities being sequentially disposed along a path of said electron beam in the order mentioned, drift tubes respectively disposed between adjacent cavities, and a collector electrode. Multi cavity klystron 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. Microwave engineering concept and objective questions. A klystron tube makes use of speedcontrolled streams of electrons that pass through a resonating cavity. The same method has been applied to tuning measurement of a diode pulsed klystron, e3712. The electron beam and cavities should be designed so as to maximize a figure of meritthe product of the voltage gain and the bandwidth of one stage of the amplifier.
Klystron tube article about klystron tube by the free. Stability analysis of cband 500kw klystron with multi. Microwave communication questions and answers pdf free download for ece mcqs objective type interview questions lab viva manual gate cat syllabus. The schematic diagram of a reflex klystron tube is shown in fig. The analytical expressions of the beamwave coupling coefficients and the beam loading conductance for a 2. Introduction to the twocavity klystron amplifier technical. Pdf multiple beam klystron research at calabazas creek.
The 2nd harmonic cavity was employed as the 3rd cavity to satisfy the phase sensitivity requirement due to the change in the beam voltage. Construction 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. Microwave engineering ece questions and answers page 7. Velocity modulation process in two cavity klystrons. The magnetic circuit formed in the neighborhood of an output cavity of a radiofrequency interaction unit is separated from the magnetic circuit of the main magnetic field generator by the radiofrequency. F input signal to the buncher cavity with the help of loop coupling. As shown electron beam is generated by electron gun which passes through the space between input cavity i. The principle of velocityvariation, first used in heil oscillators, was also used in other microwave amplifying and oscillating tubes. The present paper shall discuss the design of multi beam rf cavities for klystrons operating at 2856 mhz sband and 5 ghz cband respectively. Although each beamlet carries small amount of current, the total current can be large. Primary design of extended interaction klystron with multi.
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