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. Reflex klystron consists of an electron gun, a cathode filament, an anode cavity, and an electrode at the cathode potential. Klystron oscillator reflex klystron traveling wave tube magnetron klystron. This is most widely used in applications where variable frequency is desired as 1. 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. Mode characteristics of klystron oscillator youtube. Figure three power sources are required for reflex klystron operation.
Klystron types there are two basic configurations of klystron tubes 1. Pdf computer simulation of a twostage millimeter wave. Sep 27, 2017 in this video, i have explained reflex klystron with following points 1. Optimization of micromachined reflex klystrons for operation at. Cascade klystron selfexcited oscillator with delay. Klystron rf stabilization using feedforward circuit. Reflex klystron used as a lowpower microwave oscillator 2. How reflex klystron works electrical engineering stack exchange. This negative element is the repeller mentioned earlier.
Difference bw magnetron oscillator and klystron 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. It has an electron gun similar to that of the multicavity klystron but smaller. Performance evaluation of klystron beam focusingsystem with. P2 shows the relationship between output power, frequency and reflector voltage. 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. Modern semiconductor technology has effectively replaced the reflex klystron in most applications. Difference between two cavity klystron and reflex klystron. 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.
To study the characteristics of the reflex klystron tube and to determine its electronic tuning. Electrons in a klystron are accelerated to a controlled speed by the application of several hundred volts. Cv67 reflex klystron, velocity modulated oscillator. The klystron was invented at stanford university in 1937 and originally used as the oscillator in radar receivers during world war ii. The brothers russell and sigurd varian of stanford university are the. Reflex klystron working, oscillator and applegate diagram. Klystron and microwave department capabilities and xband. The electron beam is turned around by a negatively charged electrode that repels the beam. The results of computer simulation of a twostage millimeterwave klystron oscillator are reported. Klystron types presentday klystrons fall into three categories. It is of the same rugqedized construction as the bendix 6116tk62 the tube is, division. This type of klystron oscillator is called a reflex klystron because of the reflex action of the electron beam. When switch on the circuit, the electrons starts emitting from the cathode. Reflex klystron oscillator operation application of.
The reflex klystron makes use of velocity modulation to transform a continuous electron beam into microwave power. F input signal to the buncher cavity with the help of loop coupling. The magnetron is called as cavity magnetron because the anode is made into resonant cavities and a permanent magnet is used to produce a strong magnetic field, where the action of both of these make the device work. The klystron tube 2k25 is a single cavity variable frequency microwave generator of low. These electrons move at a uniform speed towards the anode until they are attracted by it. A klystron is a vacuum tube that can be used either as a generator or as an amplifier of power, at microwave frequencies.
Keep, the ammod amplitude knob and amfre knob at the mid position. On the klystron power supply, vswr meter and cooling fan. Klystron oscillator article about klystron oscillator by. 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. Nov 07, 2017 mode characteristics of klystron oscillator,power and frequency measurement. The stabilizing system has a holding range of several megacycles which permits the sweeping of the reference crystal oscillator. 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 frequency is primarily determined by the dimension of resonant cavity. It is given the name reflex klystron because of its reflex action of electron beam. In the a transmitter setup, a klystron produces 3 cm. The passthrough effect, therefore, contributes to the overall operating efficiency of the transmitter. Klystron oscillator reflex klystron traveling wave tube magnetron. Comsol conference 2015 grenoble multiphysics design of a klystron buncher the preliminary em analysis is the first step.
The oscillator consists of two closedloop floatingdrifttube klystrons with the output cavity. A klystron is a specialized linearbeam vacuum tube evacuated electron tube the name klystron comes from the stem form. The reflex klystron contains a reflector plate, referred to as the repeller, instead of the output cavity used in other types of klystrons. Slacpub16466 increasing klystron efficiency using com. Why is pulse modulation required in reflex klystron.
Additional cavities serve to velocitymodulate the electron beam and produce an increase in the energy available at the output. Signal source in micro wave generator of variable frequency 4. Oscillator only crossfield, e and h are at right angles relatively inexpensive very noisy can generate large spectral sidelobes nondoppler radars resonant cavities cathode and heater output coupling loop spn43c antenna. A klystron tube makes use of speedcontrolled streams of electrons that pass through a resonating cavity. Change the meter switch of klystron power supply to beam voltage position,and rotate the beam voltage knob clockwise up to 300 v deflections in meter. Modulation is accomplished by varying the velocity of the beam, which. 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. In this klystron, a single pair of grids does the functions of both the buncher and the catcher grids. Reflex klystron oscillator pdf source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. In an earlier communication on high resolution microwave spectroscopy27 we described a spectrograph using a phasestabilized klystron oscillator as a local oscillator in the detection system. In fact, according to kek injector operating statistics during 10 years in 2000s, the failures in focusing solenoids were the most frequent reasons to exchange klystron assemblies among the other. In a reflex klystron, a small modulation of the repeller voltage is more often employed to fix the emitted frequency to that of a microwave resonator by a phase locking loop technique.
The new selfexcited oscillator features a low starting current and many oscillation bands. Bershtein and his department were transferred to the radiophysical research institute rri, where he studied klystron oscillators and matched their frequencies to the frequencies of a quartz oscillator and an ammonia maser, then investigated the. 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. Klystron there are two basic configurations of klystron tubes 1. Increasing klystron efficiency using com and bac tuning and application to the 5045 klystron aaron jensen, andy haase, erik jongewaard, mark kemp and jeff neilson technology and innovation directorate slac national accelerator laboratory menlo park, ca, usa, 94025 abstract. 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 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. Typicallifetimesof8,000to15,000hourshavebeenreported. In this video, i have explained reflex klystron with following points 1. The difference between reflex and twomulti cavity klystron is that, reflex klystron uses single cavity for modulationdemodulation. It has been employed to calculate the microwave power dissipations when wall current flows on the cavity walls while it receives the operative input signal 1 w mean power at the input port.
It has been employed to calculate the microwave power dissipations when wall current flows on the cavity walls while it receives the operative input signal 50 mw mean power at the input port and emits output signal 2w at. Performance evaluation of klystron beam focusingsystem. This opened the way for the use of klystronnot only in accelerators and radar, but also in uhftv, satellite. Mode characteristics of klystron oscillator,power and frequency measurement. Keep, the ammod amplitude knob and amfre knob at the mid. Klystron us navy sps49 uhf radar klystron characteristics. A moveable detector on the waveguide can detect the waveguide potential variations using a milliameter. The development of reflex klystron as local oscillator. Source of an electronbeam and the radiofrequency por tion of the klystron is independent of the electron source. To study the characteristics of the reflex klystron tube and to determine its electronic tuning range. We know that british carefully planned all the developmental steps for their radar sets, including the use of microwaves when elsewhere the upper limit of. The klystron with internal or external feedback built in its design can function as oscillator. 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. Dti built, tested, and successfully installed a transmitter for a 2 mw, 500 mhz vkp8208a klystron.
Another tube based on velocity modulation, and used to generate microwave energy, is the reflex klystron figure 29. It is different from the two or multi cavity klystron because it uses a single cavity for modulation or demodulation. The expected lifetime of a tetrode in uhf service is usually shorter than a klystron ofthesamepowerlevel. Klausst 72fvm 36betwixt 22 reflex klystron, volker muehlhaus 21asdf44 the process is referred to as modulation. A thick cylindrical cathode is present at the center and a cylindrical block of copper, is fixed. Reflex klystron vacuum tube electromagnetism scribd.
There is a tuneable cavity which adjusts the position of the potential nodes and antinodes in the waveguide. Electrons emitted from the cathode are accelerated and passed through the positive resonator towards negative reflector, which retards and finally reflects the electrons towards the resonator. Microwave engineering reflex klystron tutorialspoint. Since all intermediate cavities in a multicavity klystron operate in the.
I think u1 may have to do with getting the reflex klystron started. Experiments with a new type of resonance microwave selfexcited system with complex dynamics, a cascade klystron selfexcited oscillator with delayed feedback, are reported. We know that british carefully planned all the developmental steps for their radar sets, including the use of microwaves when elsewhere the upper limit of usable frequencies was around 500 mhz. Cv67 reflex klystron, velocity modulated oscillator klystron reflex.
The reflex klystron oscillator is a lowpower, lowefficiency microwave oscillator, illustrated schematically in figure 118. After the war, however, very highpower klystronswere built at stanfordfor use in the first linear accelerators. The klystron beam focusing system is one of the key components in the whole system. Klystron, thermionic electron tube that generates or amplifies microwaves by controlling the speed of a stream of electrons. The main difference between two cavity reflex klystron amplifier. 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.
This paper describes a new deq circuit with feedforward compensation to stabilize the output pulse amplitude of the existing modulator for the pulse klystron. Oscillator only crossfield, e and h are at right angles relatively inexpensive. Klystron for high gradient accelerator research, in aip conf. Used in early 10 cm radar systems as a local oscillator. The oscillator consists of two closedloop floatingdrift.
Fwa, and the backwardwave amplifier and oscillator bwa and bwo are also 0type tubes, but they have nonresonant periodic. Klystron multi cavity klystron, reflex klystron, working. The klystron severed as an oscillator in radar receivers during wwii. The gunn oscillator xg11 is stable and low noise microwave source. It is known by this name due to its reflex action of electron beam. The electron beam emitted from the cathode is accelerated by the grid. The rediscovery of velocity modulation at stanford would probably have been no more successful than heils initial research in russia, except for the rumbatron. This microwave generator, is a klystron that works on reflections and oscillations in a single cavity, which has a variable frequency.
The reflex klystron is a single cavity variable frequency microwave generator of low power and low efficiency. Lowpower klystrons are used as oscillators in terrestrial microwave relay. Radar transmitter overview tube and solid state lawrence cohen radar division naval research laboratory washington, dc 20375. Reflexive klystron was used like oscillator, not classical klystron with 2 or more resonators, all thought that is possible to achieve if you put phase shifter between output and input, but effectiveness is poor. Klystron vs magnetrondifference between klystron,magnetron. Multi cavity klystron used as lowpower microwave amplifier reflex klystron reflex klystron reflex klystron single reentrant cavity as a resonator. A klystron is basically a vacuum tube with input and output structures replaced with resonant cavities known as buncher cavity and catcher cavity. Comsol conference 2016 munich multiphysics design of a ghz klystron the preliminary em analysis is the first step. In order to reduce the energy jitter pulsetopulse, a stabilization of the klystron modulator output is essential.
281 702 722 102 1323 941 944 148 501 89 228 1491 1250 1375 820 655 452 759 198 1177 168 52 1495 346 1490 481 581 2 1454 943 1089 787 1068 1009 296 236 361 980 211