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Many Small Cavities: The anode is made positive, and a magnetic field parallel to the cathode (that is, normal to the plane of the cavities) is passed through the anode interaction space from an external source. Electrons emitted by the cathode are attracted to the anode, but in passing through the magnetic field their paths are bent so that they do not immediately reach the anode but follow spiral paths such as that illustrated in Fig. 2. The cloud of electrons thus swirling around the cathode interacts with the electric fields in the cavities so that the fields oscillate at a frequency determined by the dimensions of the cavities. These oscillations are coupled out of the magnetron through a probe or slot in one of the cavities.
In high-power klystrons one or more additional cavities are generally inserted along the drift tube to increase the bunching. Since the cavities must be tuned to the frequency of the signal, the klystron is a relatively narrow-band amplifier.
The traveling-wave tube, in contrast, is a broad-band amplifier. In a typical tube the signal to be amplified is coupled to a helical transmission line, which transmits the signal in a linear direction much more slowly than it would travel in free space. An electron beam is projected through the helix in the same direction as the signal.
Food: Large variety of many small cavities invertebrates, including earthworms, insects, etc.
Eggs: Breeds on land September-November; eggs not deposited until following June-July; placed in cavities, in and under rotted logs; fastened in many small cavities groups by common stem from Roof of cavity; female usually guards eggs; hatch in 1-2 months
Larva or juvenile: Hatches with short, flat, leaflike gills which disappear in 2 or 3 days; larva is now adult but has not yet attained full growth; since it is terrestrial creature, has no need of gills or tail and back fins; reaches full growth and maturity in 2-3 years
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