See also: Microwave The content above is only an excerpt. Hansen was instrumental in the development of the klystron and was cited by the Varian brothers in their paper. Additional "buncher" cavities added between the first "buncher" and the "catcher" may be used to increase the gain of the klystron or to increase the bandwidth. The electron beam is velocity modulated when it first passes through the cavity. The first section provides background information and explains the objectives of the boreal forest experiment. The DC bias on the drift tube may be adjusted to alter the transit time through it, thus allowing some electronic tuning of the oscillating frequency.
Reflex klystrons are almost obsolete now. Reflex klystron[ edit ] Low-power Russian reflex klystron from Today the scientific community is working towards improving the quality of the accelerated beam and its parameters, while trying to develop technology for reducing accelerator size. The cavity resonator from which the output is taken, is attached to the electrodes labeled Externer Resonator. During the Second World War , the Axis powers relied mostly on then low-powered and long wavelength klystron technology for their radar system microwave generation, while the Allies used the far more powerful but frequency-drifting technology of the cavity magnetron for much shorter-wavelength one centimeter microwave generation.
The electrons are fired into one end of the tube by an electron gun. Links to Primary Literature Additional Readings An evacuated electron-beam tube in which an initial velocity modulation imparted to electrons in the beam results subsequently in density modulation of the beam. Today the scienti c community is working towards improving the quality of the accelerated beam and its parameters while trying to develop technology for reducing accelerator size. 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.
Beyond the buncher grids is a space called the drift space. The output terminal is visible at top. An external electromagnet winding creates a longitudinal magnetic field along the beam axis which prevents the beam from spreading. The electric field causes the electrons to "bunch": electrons that pass through when the electric field opposes their motion are slowed, while electrons which pass through when the electric field is in the same direction are accelerated, causing the previously continuous electron beam to form bunches at the input frequency. It was used as a local oscillator in some radar receivers and a modulator in microwave transmitters the s and s, but is now obsolete, replaced by semiconductor microwave devices.
Sign In Get AccessScience for your institution. On the left are the cathode and accelerating anode, which create the electron beam.
Precautions are routinely taken when transporting klystron devices in aircraft, as the intense magnetic field can interfere with magnetic navigation equipment. This type of oscillator klystron has an advantage over the two-cavity klystron on which it is based, in that it needs only one tuning element to effect changes in frequency. 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. In this manner, the uniform current density of the initial beam is converted to an alternating current. The well phase-locking effect of the RBWO-WKA system requires the oscillator have good frequency reproducibility and stability from pulse to pulse.
The buncher grids have an oscillating AC potential across them, produced by standing wave oscillations within the cavity, excited by the input signal at the cavity's resonant frequency applied by a coaxial cable or waveguide. The DC bias on the drift tube may be adjusted to alter the transit time through it, thus allowing some electronic tuning of the oscillating frequency.