The simplest klystron tube is the two cavity klystron. In a multi beam klystron mbk, a high current electron. Introduction to the twocavity klystron amplifier technical. These will set up a field in the third cavity, which produces more concentrated bunches and. These electrons move at a uniform speed towards the anode until they are attracted by it. On the other hand, klystrons are narrowband devices, compared with travellingwave tubes. Design and performance of lband and sband multibeam. When switch on the circuit, the electrons starts emitting from the cathode. Design of a highefficiency sband klystron with a multi. The perturbation theory multicavity largeorbit gyroklystron. The present paper shall discuss the design of multi beam rf cavities for klystrons operating at 2856 mhz sband and 5 ghz cband respectively. The main characteristics of a delayedfeedback multiple cavity klystron. Another system consists of a single vhf cavity energized by a triode tube that is less expensive than klystron. The basic electrode arrangement of a reflex klystron is given below.
One very important item that is required for highpower klystron amplifier operation is an axial magnetic field a magnetic field parallel to the axis of the klystron. Timedomain picmodeling of suppression of selfmodulation in the multiple cavity klystron oscillator with delayed feedback. F input signal to the buncher cavity with the help of loop coupling. Since all intermediate cavities in a multicavity klystron operate in the. We simulated the beamdynamics using the field charge interaction fci code with a matlab script to find the optimum design parameters for high efficiency. The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. 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 disposed at the end. A broadband rectangular reentrant cavity for multiple beam klystron. There are often several regions of reflector voltage where the reflex klystron will. Tuning measurement of multicavity klystrons in diode mode. In order to investigate how the efficiency of the 5ghz 500kw cw klystron prototype could be enhanced, the cavity design study is being carried out with.
The paper presents an application of perturbation theory to multi cavity largeorbit gyro klystron. The analytical expressions of the beamwave coupling coefficients and the beam loading conductance for a 2. A breakthrough solution to this gridlock is to use multiple low perveance beamlets in parallel in the same vacuum envelop. So for a constant cathode voltage it is possible to find for an individual accelerating structure the optimal output power while maintaining high klystron efficiency. The following figure depicts an example of multi cavity klystron amplifier.
In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. 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. A broadband rectangular reentrant cavity for multiplebeam. At these narrow dimensions, the device is critically exposed to multiple physics effects, due to the power dissipations and external environment, influencing the electromagnetic. Design of a multi beam klystron cavity from its single. The entire drifttube assembly, the three cavities, and the collector plate of the three cavity klystron are operated at ground potential for. Timedomain picmodeling of the multiple cavity klystron oscillator with delayed feedback. There are few intermediate cavities used between buncher cavity and catcher cavity. With the signal applied in the first cavity, we get weak bunches in the second cavity. For highperveance p 10 mu pervs, highpower p 10 kw electron beams, it is relatively straightforward to design a broadband output cavity. Ppt klystron powerpoint presentation free to view id. At a very high temperature, the cathode emits electrons.
The multi cavity klystron consist of a glass envelope in which there is an electron gun composed of heater and cathode. All the multiple choice questions which are provided in the microwave engineering ece quiz are essential for the competitive examinations. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. 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. Stability analysis of cband 500kw klystron with multi. 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. It is known by this name due to its reflex action of electron beam. A twt is sometimes preferred to the multi cavity klystron amplifier because the former. Resonant cavity accelerators consist of several resonant cavities in series energized by a single sband klystron using a microwave power distribution system 25. The newly developed klystrons should have the same specifications, including perveance and overall length, to replace existing ones. Microwave engineering kg reddy college of engineering. Thus, the aspirants can practice the microwave engineering ece mcq online test to learn the microwave engineering ece questions and. The frequency of operation of a klystron is set by the sizes of the input and output cavities.
A network is arranged in the hub of multi cavities to let the flow of electrons. Design of a highefficiency sband klystron with a multicell. 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. Microwave communication questions and answers pdf free download for ece mcqs objective type interview questions lab viva manual gate cat syllabus microwave communication questions and answers. Archived from the original pdf on september 24, 2015. The electron beam first passes through a cavity to which the input signal is applied. The multi cell cavity can provide the higher power and the wider bandwidth, however there. Under these limited conditions, we designed the klystrons based on a multi cell output cavity to improve the powerconversion efficiency significatly.
Multi beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3d code only. It is given the name reflex klystron because of its reflex action of electron beam. Comparison has been made with the results in normal triode operation and has shown a good agreement. In a multicavity 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. What is a klystron amplifier, types, differences and their. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. Vidyalankar group of educational institutes 947 views 8. Other articles where twocavity klystron is discussed. The klystron with internal or external feedback built in its design can function as oscillator.
The schematic diagram of unequalwidth slots structure with nine gaps is shown in fig. 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. A klystron is a specialized linearbeam vacuum tube, invented in 1937 by american electrical. The analytical design of the cavity has been performed solving the system of equations described by carter 3. Multicavity klystron amplifiers nippon electric co. The multi cell cavity can provide the higher power and the wider bandwidth, however there is a possibility to generate the self. By referring to this nomenclature, we propose the following proportions for cavity dimensioning.
In this tube there are two microwave cavity resonators, the catcher and the buncher. 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. Multicavity klystron article about multicavity klystron. Klystron vs magnetrondifference between klystron,magnetron. The simulations show that the efficiency is close to. In a multicavity klystron amplifier of the class comprising an electron gun for emitting an electron beam. An electron discharge tube of klystron type comprising an evacuated housing forming a plurality of drift tubes and cavity resonators interposed between the drift tubes, an electron gun within said housing for producing an electron beam, a collector within said housing distally spaced from said electron gun for receiving said electron beam, and a. 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 closely bunched. The multicavity power klystron klystron amplification, power output, and efficiency can be greatly improved by the addition of intermediate cavities between the input and. There are two cavities known as buncher and catcher cavity.
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. An output cavity tuner allows the klystron to be tuned for maximum efficiency when the operating current is reduced. Multicavity klystron article about multicavity klystron by. Furthermore, some analytical expressions are derived, such as the bunching formula of electrons, beamwave interaction power. Mar 02, 2018 two cavity klystron amplifiers working, amplification and applegate diagram by engineering funda duration. In a multicavity 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. The present paper shall discuss the design of multi beam rf cavities for klystrons operating at 2856 mhz sband and 5. Jul 31, 2018 the two cavity klystron utilizes an electron source heater, an anode, and a cathode like a conventional vacuum tube. Klystron power supply skps610 multi meter klystron mount xm251 isolator xi621 variable attenuator xa520 frequency meter xf455 detector mount xd451 vswr meter sw115 cro theory. Philips also devised some multireflex structures, see. While a conventional klystron has one interaction gap per cavity. By lowering the qs of the cavities and by introducing intermediate cavities, wider bandwidth operation can be achieved. The vacuum tube consists of a cathode, which is heated by a filament. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity.
Stability analysis of cband 500kw klystron with multicell. The mechanism of the beamwave synchronization and the coupling in the multi gap cavity at 225 ghz are studied in. Here, the primary cavity by the pairing device is called as a buncher whereas. A two cavity klystron without a feedback path will operate as what type of circuit. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Design considerations for the highpower multicavity klystron ieee. The heater boils off electrons when heated and the electrons are ejected from the cathode and accelerate towards the anode due to the high dc potential. The mechanism of the beamwave synchronization and the coupling in the multi gap cavity. In this way, even ceramics of extremely small, which was difficult to heat with multi mode cavity, became possible to heat easily up to high temperature by using singlemode cavity of 6ghz. The 2nd harmonic cavity was employed as the 3rd cavity to satisfy the phase sensitivity requirement due to the change in the beam voltage. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. The main difference between two cavity reflex klystron amplifier. This embodiment results in highpowered klystrons capable at working. As shown electron beam is generated by electron gun which passes through the space between input cavity i.
The number of beamlets introduces a new degree of freedom in parameter space. 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. Microwave engineering ece questions and answers page 2. A multiplebeam klystron comprising several resonant cavities, with drift tubes in which the dimensions of the cavities are set in such a way that the klystron works optimally in the mode tm 0n n being a whole number greater than 1, a klystron in which the drift tubes cross the cavities, passing through a region where, even in the absence of these tubes, the electrical field would have an. It was possible to obtain optimized design parameters with better efficiency for a cavity system adopting a multi cell output cavity. Amplification of such two cavity klystron is low and hence multi cavity klystrons are used. Other articles where two cavity klystron is discussed. A three cavity klystron is illustrated in figure 28. Design of a multi beam klystron cavity from its single beam. A confinedflow largesignal formulation of the klystron interaction equations is presented and applied to the analysis of the multicavity klystron amplifier. 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.
A variable highpower multibeam klystron design sciencedirect. Microwave tubes and circuits from the book electronic communication systems by george kennedy. 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. Broadband and highpower terahertz radiation source based. What is a klystron amplifier, types, differences and their applications. Initial set of scan parameters was obtained by benchmarking the e3762 klystron. After the electron gun there are two focusing electrodes used to keep the electron beam in the center around the glass envelope. The bunches of electrons excite microwaves in the output cavity of the klystron. The bandwidth of a klystron output cavity scale approximately as. Primary design of extended interaction klystron with multi. 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. It is physically shorter than a klystron because of the absence of a multicavity buncher. Microwave engineering cavity klystron tutorialspoint. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output.
Diploma sem v two cavity klystron amplifier microwave and radar lecture vidyalankar duration. It also utilizes a collector element at the end of the electron stream. Since all intermediate cavities in a multicavity klystron operate in the same manner, a representative three cavity klystron will be discussed. The simulation has been done with the fci field charge interaction code aided by a matlab script for scanning input parameters. Klystron multi cavity klystron, reflex klystron, working. The same method has been applied to tuning measurement of a diode pulsed klystron, e3712. The two cavity klystron uses what cavity as an output cavity. Difference between two cavity klystron and reflex klystron. This is the multiple choice questions in chapter 11. 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 accelerator. Philips also devised some multi reflex structures, see.
K j and datta, s k 2019 a broadband rectangular reentrant cavity for multiple beam klystron. Pdf timedomain picmodeling of the multiple cavity klystron. Mar 10, 2016 multi beam klystron cavity design is a critical task due to asymmetric cavity structure and can be simulated by 3d code only. The multi defect structures described above allow a. In klystron amplifiers, which are physi cally long, it is difficult to keep the electron beam properly formed during its travel through the rf section. It is different from the two or multi cavity klystron because it uses a single cavity for modulation or demodulation. Mcq in microwave communications part 4 ece board exam. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity.