Microwave Tubes for scientific applications - Indian context

Microwave tubes cover the wide range of RF spectrum. Up to 30 GHz they are usually termed as microwave tubes and beyond that they are known as millimeter wave tubes. They are widely used for generation and amplification of RF signals. These devices came into prominence around World War - II when pulse magnetrons were substantially used in radar systems. Later on, other devices like klystron, backward wave oscillators, traveling wave tubes, crossed field amplifiers were invented and used in various systems. All these type of devices are known as slow-wave devices, in which interaction takes place between an electron beam and slow RF wave propagating in the RF structure. The disadvantage of this class of device is their limitation of handling large powers at high frequencies due to the smaller geometries of the RF structure. The other class of devices, which are termed as fast-wave, and there the interaction takes place between a relativistic gyrating electron beam in presence of magnetic field and the fast RF wave propagating in the wave guide or cavity type of RF circuit. This enables them to handle very large powers up to very high frequencies. These devices are known as gyro devices and most prominent among them is gyrotron.