Microwave Engineering Cavity Klystron – Learn Microwave Engineering in simple and Amplification of such two-cavity Klystron is low and hence multi-cavity. Klystron Amplifiers: Description of the function of the Two-Cavity Klystron and the Reflex (Repeller) Klystron. Two-cavity klystron: electron tube: Klystrons: explained in terms of a two-cavity klystron amplifier.
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As all the cavity resonators are identical, the movement of electrons makes the second resonator to oscillate.
What is a Klystron Amplifier? Types and their Applications
Some klystrons employ permanent magnets. In a klystron, an electron beam interacts with radio waves as it passes through resonant cavitiesmetal boxes along the length of a tube.
Perhaps we can digress a moment to discuss the cavity used in the buncher and the catcher. July 31, by Mark Mitchell Klystron amplifiers are used in a variety of industries, including satellite systems, television broadcasting, amplifief, particle accelerators, and in the medical field. In the output “catcher” cavity, each bunch enters the cavity at the time in the cycle when the electric field opposes the electrons’ motion, decelerating them.
The two-cavity klystron utilizes an electron source heateran anode, and a cathode like a conventional vacuum tube. The now klystrln rightmost grid pushes them faster as it repels them on exit. In the reflex klystron the electron beam passes through a single resonant cavity.
In a vacuum, a beam of electrons is emitted by a thermionic cathode a heated pellet of low work function materialand accelerated by high-voltage electrodes typically in the tens of kilovolts.
The electrons while passing through the second cavity, few of them are accelerated while bunches of electrons are decelerated. On the opposite electrical cycle of the plates, the electrons encounter a positive grid initially, which pulls on them and accelerates them through the buncher grids.
Popular Science’s “Best of What’s New ”   described a company, Global Resource Corporation, currently defunct, using a klystron to convert the hydrocarbons in everyday materials, automotive waste, coaloil shaleand oil sands into natural gas and diesel fuel.
Radar Basics – Klystron Amplifier
Electrically, this is similar to the two cavity oscillator klystron with a lot of feedback between the two cavities. The electronic tuning range of the reflex klystron is usually referred to as the variation in frequency between half power points—the points in the oscillating mode where the power output is half the maximum output in the mode. The amplified signal is extracted from the catcher cavity through a coaxial cable or waveguide.
The whole set up is as shown in the following figure.
Thus the oscillating field in the catcher cavity is an amplified copy of the signal applied to the buncher cavity. Russ Cochran, p. Hence, usually the electrons have a constant speed in the gap between the cavity resonators.
This cabity and thus the charge applied k,ystron anything passing through the central hole will flip charge at the resonant frequency. The residual kinetic energy in the electron beam when it hits the collector electrode represents wasted energy, which is dissipated as heat, which must be removed by a cooling system.
The electrons are attracted to and pass through an anode cylinder at a high positive potential; the cathode and anode act as an electron gun to produce a high velocity stream of electrons. The field direction changes with the frequency of the Buncher cavity. 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.
This result gives an advantage for controlling of an automatic frequency in receivers, and in FM frequency modulation for transmitters.
On each side of the cavity hole is a grid that the electrons pass through. To understand the modulation of the electron beam, entering amlpifier first cavity, let’s consider the electric field.
Electrons in a beam leaving a source at high velocity all have a roughly equal velocity in the direction of travel.
In all modern klystrons, the number of cavities exceeds two. The drift tube is electrically insulated from the cavity walls, and DC bias is applied separately. The function of the catcher grids is to absorb energy from the electron beam. A conductor has amplififr electrons.
The electrons in the beam are velocity-modulated before the beam passes through the cavity the second time and will give up the energy required to maintain oscillations. As the electrons are negatively charged, they are accelerated if moved opposite to the direction of the electric field. In most applications, reflex klystron is effectively replaced by the modern semiconductor technology. Retrieved from ” https: The level of modulation applied for transmission is small enough that the power output amplifir remains constant.
While moving, these electrons enter the field free space called as the drift space between the resonators with varying speeds, which create electron bunches. Now we are in a big bunch traveling down the drift space. Journal of Applied Physics. First I will take you through the theory, and later I Each bunch of electrons passes between the grids at a point in the cycle when the exit grid is negative with respect to the entrance grid, so the electric field in the cavity between the grids opposes the electrons motion.
Western Union Telegraph Company also built point-to-point microwave communication links using intermediate repeater stations at about 40 mile intervals at that time, using 2K25 reflex klystrons in both the transmitters and receivers. Low-power klystrons are used as oscillators in terrestrial microwave relay communications links, while high-power klystrons are used as output tubes in UHF television transmitterssatellite communicationradar transmittersand to generate the drive power for modern particle accelerators.
Depending on this, the electrons coming out of the qmplifier gun, get their pace controlled. In this type of klystron amplifier, the electron beam flows through a single resonant cavity. The result is a density modulation or bunching proportional to the applied force on the electrons as imparted by the buncher resonant cavity does that start to sound useful?
As the inductance of the loop is very small, high frequency can be obtained. January Learn how and when to remove this template message. These amplifiers use cavities to modulate the electric field nearby the axis of the tube. The plate that klystorn more electron deposition will be the cathode klyatron the plate which klystrob lesser number of electrons becomes the anode.
This alternating current gives rise to alternating magnetic field, which is out of phase with the electric field of the capacitor. Additional cavities serve to cavihy the electron beam and produce an increase in the energy available at the output.