Traveling wave tube

From Glossary of Meteorology

traveling wave tube

(Abbreviated TWT.) A linear beam amplifier tube used in medium-power radar transmitters.

In a TWT, a stream of electrons interacts continuously or repeatedly with a guided electromagnetic wave moving substantially in synchronism with it and in such a way that there is a net transfer of energy from the stream to the wave. A TWT is characterized by high bandwidth but has somewhat lower gain, power, and efficiency than a klystron.