2 cavity klystron pdf files

On each side of the cavity hole is a grid that the electrons pass through. But klystrons have limited bandwidth less than 2% because of their use of resonant cavities. The klystron is the most widely diffused rf source in particle accelerators. The following figure depicts an example of multicavity klystron amplifier.

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. Jan 07, 2019 reflex klystron pdf posted on january 7, 2019 by admin 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. Jun 15, 2005 the direct and comb loop feedback around the rf cavities in pepii is critical in reducing longitudinal instabilities driven by the cavity impedance. The direct and comb loop feedback around the rf cavities in pepii is critical in reducing longitudinal instabilities driven by the cavity impedance. Observe the graph of the empty cavity and the cavity filled with samples, and note down the shift in resonant freq tangent and dielectric constant of the materials. The sixcavity test demonstrated acceleration of beam. Amplification of such twocavity klystron is low and hence multicavity klystrons are used. Microwave engineering ece questions and answers page 2. Klystron versus repeller voltage for reflex klystron. Stability analysis of cband 500kw klystron with multicell. 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.

For this article, however, we will focus on another popular type. The klystron was the first embodiment of the velocity modulation principle. The most impressive power achieve ments at very good efficiencies continue to occur in the gyrotron area. Cavity of a repeller klystron another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron repeller klystron. High power cw tubes up to 2 mw, for synchrotron, storage rings and cw linacs. Perhaps we can digress a moment to discuss the cavity used in the buncher and the catcher.

The essential elements of klystron are electron beams and cavity resonators. Multicavity klystron efficiency and bandwith additional cavities are used to increase gain, bunches are formed by the first n1 cavities power is extracted by the n th cavity perveance electron gun is a spacecharge limited diode with given by k. The vacuum tube consists of a cathode, which is heated by a filament. Introduction to the twocavity klystron amplifier technical. Two cavity klystron amplifiers working, amplification. Progress of the klystron and cavity test stand for the. To read and print pdf files, download adobe acrobat reader. The small dcblocked cavity rests on top of the tube, as illustrated in figure 6. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency. Since all intermediate cavities in a multicavity klystron operate in the same manner, a. Content introduction of two cavity klystron construction of two cavity klystron two cavity klystron amplifier performance characteristics application 3. Next, select file from aj disks menu, and from within the file menu select open.

In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. A klystron is a microwave vacuum tube using cavity resonators to produce velocity modulation of the electron beam and produce amplification. For the generation and amplification of microwaves, there is a need of some special tubes called as microwave tubes. Because the bandwidth of the buncher section could be increased by stagger tuning 1, the output cavity was seen as the bandwidthlimiting element of the klystron design. A twocavity klystron amplifier has the following parameters. Lowpower klystrons are used as oscillators in terrestrial microwave relay. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. In font of cavity resonator a huge crowed of electrons assembles and excites cavity, the oscillation it the cavity takes place and hence we get the r. Klausst 72fvm 36betwixt 22 reflex klystron, volker muehlhaus 21asdf44 the process is referred to as modulation. These electrons move at a uniform speed towards the anode until they are attracted by it. Download scientific diagram schematic diagram of a twocavity klystron amplifier. I think u1 may have to do with getting the reflex klystron started.

Klystron is a vacuum tube used for the amplification and generation of microwave signal operation. It is the interaction of the cavities with the beam that provides the high levels of amplification that the device can produce. A two cavity klystron amplifier has the following parameters. A millimeterwave klystron upconverter with a higher order. The reflex klystron is mostly used as a microwave oscillator. So far, weve taken b 1 in treating beamcavity interaction, which allows for the approximation of the beam as an ideal current source i. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. In the rf section for the present klystron, there are five cavities, which consist of one input cavity. P2 shows the relationship between output power, frequency and reflector voltage. A threecavity klystron is illustrated in figure 2 8.

The function of the catcher grids is to absorb energy from the electron beam. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. The ranges of all these voltages are given in the specification data sheet. Complex dynamics of a two cavity klystron oscillator with delayed feedback. A 500 kw lband klystron with broad bandwidth for sub. The following figure depicts an example of multi cavity klystron amplifier. Klystrons can be used in the uhf region 300 mhz to 3 ghz up to 400 ghz. 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. The cavity is a quarterwave transmission line, as measured from the top of the cav.

It is given the name reflex klystron because of its reflex action of electron beam. Jul 31, 2018 on each side of the cavity hole is a grid that the electrons pass through. Ph0101 unit 2 lecture 6 3 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. Ms purva sharma, assistant professor, biyani girls college explained about two cavity klystron. It is different from the two or multi cavity klystron because it uses a single cavity for modulation or demodulation. Amplification of such two cavity klystron is low and hence multi cavity klystrons are used.

The quantity of tubes needed for the application is very small so that a costly. The electron gun emits the electron beam, which passes through the gap in the anode cavity. In this tube there are two microwave cavity resonators, the catcher and the buncher. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. This requires a combination of bandwidth and short group delay within the klystron. Klystron, including the reflex and multicavity klystron. Introduction a klystron is a vacuum tube that can be used either as a generator or as an. One major type is the reflex klystron, which is used primarily as an oscillator. Observe the 3db bandwidth for empty cavity and note down the resonant frequency. Reflex klystron reduced power from the bunches, in reflex klystron, reduces the reflex klystron of the cavity oscillations and causes a decrease in output power. Two cavity klystron amplifiers working, amplification and. Aug 30, 2016 ms purva sharma, assistant professor, biyani girls college explained about two cavity klystron.

Firstly, as we know that klystrons are used as amplifiers for microwave frequency and conventional vaccum tubes cant be used due to interelectrode capacitance and lead. Rms cavity field magnitude and phase variation across the pulse with beam and rfqklystron feedback. Z239 klystron two cavity klystron klystron reflex cv2187 two cavity resonator cavity resonator text. Signal from the output cavity is measured by a spectrum analyzer attached to the output waveguide. At a very high temperature, the cathode emits electrons. Repeat the same steps for cavity filled with teflon and compare the two results. Download scientific diagram schematic diagram of a two cavity klystron amplifier. Pdf complex dynamics of a twocavity klystron oscillator. Replaced with new thales klystron sn 089048 efficiency at 650kw output is 45% lower than other thales klystrons some sideband instabilities, but. Jun 02, 2014 i am reading two cavity klystrons but not able to understand at all. Caryotakis, performance of a 150mw sband klystron, aip conf. 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. As a result, the effective smallsignal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power amplifier.

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. The frequency is primarily determined by the dimension of resonant cavity. Other articles where twocavity klystron is discussed. Firstly, as we know that klystrons are used as amplifiers for microwave frequency and conventional vaccum tubes cant be used due to interelectrode capacitance and lead inductance effect,but though microwave signals can be amplified by klystrons is there any limitation to. As a result, the effective smallsignal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power. Derive an expression for the efficiency of the klystron amplifier. The main difference between two cavity reflex klystron amplifier. I am reading two cavity klystrons but not able to understand at all. The unique set of characteristics of this tube were strongly guided by requirements of the fast feedback necessary to prevent oscillations of the storage ring beams caused by the detuned accelerating cavity. Review of highpower microwave source research this.

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. It is known by this name due to its reflex action of electron beam. F output from the cavity with the help of loop coupling. Functional and schematic diagram of a twocavity klystron. The klystron amplifier can be used as an microwave oscillator or amplifier at low and high frequencies. Understandexplain is the principle of working for two cavity klystron with velocity diagram. F input signal to the buncher cavity with the help of loop coupling. The feedback path provides energy of the proper delay and phase relationship to sustain oscillations. The catcher grids are placed along the beam at a point where the bunches are fully formed. The twocavity klystron in figure 2 7a and b may be used either as an oscillator or an amplifier. Klystron rf cavity tuning nuts were found to be loose on cavities 3 and 4 eev sn 01 retired permanently. 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 figure, where they are acted upon by a radiofrequency field, which causes a bunchingup effect.

Oct 01, 2014 338 microwave linearbeam tubes 0 type chap. The configuration shown in the figure is correct for oscillator operation. Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. They require high supply voltages in the region of hundreds of. Pdf a twostage oscillator consisting of two coupled three cavity klystrons is studied.

A large variety of tubes exists for different applications, spanning wide ranges of frequency and output power, as well as different duty cycles. Nov 12, 2014 klystron produced excessive 2 ndharmonic powerwhy. Difference between two cavity klystron and reflex klystron. These will set up a field in the third cavity, which produces more concentrated bunches and. In the process, he invented the microwave cavity i. Introduction a klystron is a vacuum tube that can be used either as a generator or as an amplifier or as an oscillator, at microwave frequencies. When switch on the circuit, the electrons starts emitting from the cathode. A 500 kw lband klystron with broad bandwidth for subharmonic. Question bank department of electronics and communication. 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. With moderate 40 w drive power, the klystron output power reaches 1 mw 90 dbm. Diode drive cavity idler cavities output cavity collector f 2996 mhz gain 55 db efficiency. A cw klystron operating at 476 mhz has been developed jointly by slac and varian associates.

A reflex klystron is an obsolete type in which the electron beam was reflected. In this video, i have explained two cavity klystron amplifier with following points 1. Klystron multi cavity klystron, reflex klystron, working. Sep 27, 2017 in this video, i have explained two cavity klystron amplifier with following points 1. Other articles where two cavity klystron is discussed. With the signal applied in the first cavity, we get weak bunches in the second cavity. Pdf simulation of a 95 ghz twostage threecavity klystron oscillator.

Klystron tube article about klystron tube by the free. Stability analysis of cband 500kw klystron with multi. Microwave engineering reflex klystron tutorialspoint. Klystron tube 2k25 the klystron tube 2k25 is a single cavity variable frequency microwave generator of low power and low efficiency. Two forms of such a device, also called linear beam klystron, are given in the following figure. The simplest klystron tube is the two cavity klystron.