Operation of twt and magnetrons

They made the big-gunned Allied battleships more deadly and, along with the newly developed proximity fuzemade anti-aircraft guns much more dangerous to attacking aircraft.

Due to size and layout considerations, installing enough limiting resistors to handle all of this dissipation is not always practical. This configuration is used in beam-focusing devices as well as in a class of devices called magnetrons see the section Magnetrons.


A voltage applied across the cathode and anode accelerates the electrons towards the far end of the tube, and an external magnetic field around the tube focuses the electrons into a beam.

For example, for ion sources where an external series resistor is normally provided, the arc counting feature is not needed. Page 1 of 3. The electrons are continually slowed down, and their energy is transferred to the wave along the helix. The magnetron at the middle of the figure is connected to the waveguide by a coaxial connector.

The cavity oscillations produce electric fields that spread outward into the interaction space, as shown in the figure. Single or chronic exposure can lead to berylliosisan incurable lung condition.

Typical elements of a gyrotron. Typical gains are on the order of 4 decibels per centimetre, and overall gains are 40 to 60 decibels for helix tubes of practical sizes and applications. Because cavities have bandwidth limitations, the coupled-cavity TWT also is bandwidth-limited to typically 10 to 20 percent.

It was also noticed that the frequency of the radiation depends on the size of the tube, and even early examples were built that produced signals in the microwave region. Wrapped around the inside of the tube, just outside the beam path, is a helix of wire, typically oxygen-free copper.

It not only changed the course of the war by allowing us to develop airborne radar systems, it remains the key piece of technology that lies at the heart of your microwave oven today. Spaced around the rim of the chamber are cylindrical cavities. In another major type of fast-wave tube, an electromagnetic wave travels down a circular or rectangular waveguide and interacts with an undulating electron beam.

The best known example is the klystron. Attenuators placed along the RF circuit prevent the reflected wave from traveling back to the cathode. Inthe problem of frequency instability was solved by James Sayers coupling "strapping" alternate cavities within the magnetron which reduced the instability by a factor of The power levels of klystrons are achieved through the use of large beam voltages and currents.

Cavity magnetron

If the radar is moving relative to the target as when the radar is on an aircraft and the target is the groundthe Doppler frequency shift will be different for different parts of the target.

Range, or distance, is determined by measuring the total time it takes for the radar signal to make the round trip to the target and back see below.

As this normally causes more electrons to be released, it could sometimes lead to a runaway effect, damaging the device.

If the phase is proper, this current adds to the current associated with the RF wave flowing in the helix and causes the wave to grow. The RF signal to be amplified is fed into the Operation of twt and magnetrons at a point near the emitter end of the tube. This older magnetron uses two horseshoe shaped alnico magnets, modern tubes use rare earth magnets.

For example, if the time that it takes the signal to travel out to the target and back was measured by the radar to be 0.

Wrapped around the inside of the tube, just outside the beam path, is a helix of wire, typically oxygen-free copper. The transmitter must be efficient, reliable and easy to maintain and the life expectancy and cost of the output device must be acceptable.

The resolution in angle, or cross range, that can be obtained with conventional antennas is poor compared with that which can be obtained in range. This depth is designed so that if the power supply is operated without the insertion of the mating cable, personnel cannot come in contact with dangerous voltages.

An electric field can be used to change the path of the electron stream, alter the number of flowing electrons change the electric currentand modify their speed. As power level increases, the wire can overheat and cause the helix geometry to warp. In addition, we typically employ large window U-cores which give enough space for the proper gradients.

The currents in electron tubes are small enough in most cases that their effect on the magnetic field is usually negligible. Note that Kompfner's US patent, granted indoes cite Haeff's previous work. The power gain of the klystron is dependent on the voltage and current as well as on the number of cavities used.If the input-waveguide introduces an oscillation into the first resonator (as shown in figure 3), the vanes of the resonator gets a voltage difference synchronously to the oscillation.

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Electron tube: Electron tube, device usually consisting of a sealed glass or metal-ceramic enclosure that is used in electronic circuitry to control a flow of electrons. Among the common applications of vacuum tubes are amplification of a weak current, rectification of an alternating current (AC) to direct.

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Operation of twt and magnetrons
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