Difference between Magnetron and Reflex Klystron

Difference between Magnetron and Reflex Klystron

The basic difference between Magnetron and Reflex Klystron is based on their type of tube. The magnetron is a cross-field device. These are generally referred to as M-type tubes. Reflex klystron is a linear beam device. These are generally referred to as O-type tubes.

Reflex Klystron

It is a single cavity variable frequency microwave generator of low power and low efficiency. If a fraction of the output power is fed back to the input cavity and if the loop gain has a magnitude of unity with a phase shift which is a multiple of 2π, the klystron will oscillate. It produces an output power in the range of 10–500 mW and a frequency in the range of 1 to 25 GHz. This type is widely used in the laboratory for microwave measurements. For applications that require variable frequency, Reflex klystron is used.

Magnetron

The magnetron is a crossed field device, in which electric field and magnetic field are produced in a direction perpendicular to each other, in a way to cross each other. Therefore, the flow of electrons is perpendicular to both fields. In magnetrons, anode and cathode are concentric and cylindrical type structures. The magnetic field causes the electrons that are emitted from the cathode to move in curved paths. Magnetrons use various shapes of cavities to build oscillations and power.

Comparison of magnetron and reflex klystron tubes

S.No.MagnetronReflex klystron
1The magnetron is a cross-field device. These are generally referred to as M-type tubes.Reflex klystron is a linear beam device. These are generally referred to as O-type tubes.
2The electrons carrying energy are made to interact with the RF field for a long duration.The electrons carrying energy are in contact with the RF field for a short duration.
3The range of frequencies over which magnetrons work properly is 500 MHz to 12 GHz.The range of frequencies over which reflex klystron works properly is 1-25 GHz.
4The efficiency provided by magnetrons is in the range of 40 to 70%.The efficiency provided by reflex klystron is very less than magnetrons and is in the range of 10 to 20%.
5For these tubes, the output power is in the range of 2 mW to 250 kW.For these tubes, the output power is in the range of 1 mW to 2.5 W.
6A permanent magnet is used that generates the magnetic field; it is so placed that the magnetic field is perpendicular to the electric field inside the magnetron.No permanent magnet is used here, but a repeller electrode is used at the end of the tube that bounces back the electron beam.
7Magnetrons are used for industrial heating and microwave ovens.Reflex klystron is used as a signal generator in microwave radars or receivers.

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