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The cavity magnetron is a high-power vacuum tube used in early radar systems and subsequently in microwave ovens and in linear particle accelerators. A cavity magnetron generates microwaves using the interaction of a stream of electrons with a magnetic field , while moving past a series of cavity resonators , which are small, open cavities in a ...
Electrically, this is similar to the two cavity oscillator klystron with considerable feedback between the two cavities. Electrons exiting the source cavity are velocity modulated by the electric field as they travel through the drift tube and emerge at the destination chamber in bunches, delivering power to the oscillation in the cavity.
He was the leader of a group working on the cavity magnetron from April 1940 in north-west London. [7] The cavity magnetron was producing power of around 500W (E1188 version). Eric Megaw changed the design, coating the cathode with oxides (E1189 version) [ 8 ] and eight segments from six, to increase the power to 100 kW by September 1940 ...
The magnetron was initially limited to aircraft operating over the UK or sea, so that if the aircraft was lost the magnetron would not fall into German hands. However, as the war progressed several new uses for the magnetron were developed, notably ground-mapping systems like the H2S radar .
Original cavity magnetron, 1940. This was developed by John Randall (1905-1984) and Harry Boot (1917-1983) at Birmingham University. Radars that could produce clear images of distant objects played a decisive role in World War II, by bouncing powerful, ultra-short radio waves off their targets.
Sir John Turton Randall, FRS FRSE [2] (23 March 1905 – 16 June 1984) was an English physicist and biophysicist, credited with radical improvement of the cavity magnetron, an essential component of centimetric wavelength radar, which was one of the keys to the Allied victory in the Second World War.
The Hull magnetron was tested as an amplifier in radio receivers and also as a low-frequency oscillator. It was reported in 1925 that a magnetron made at GERL could generate a power of 15 kW at a frequency of 20 kHz. At the time Hull anticipated that the magnetron would find greater use as a power converter than in communication applications.
Cavity resonators are widely used as the frequency determining element in microwave oscillators. Their resonant frequency can be tuned by moving one of the walls of the cavity in or out, changing its size. An illustration of the electric and magnetic field of one of the possible modes in a cavity resonator.