Re: how TWT work
A traveling wave tube (TWT) is an electronic device used to produce high-power radio frequency signals.
The device is an elongated vacuum tube with an electron gun (a heated cathode that emits electrons) at one end. A solenoid coil wrapped around the tube creates a magnetic field which focuses the electrons into a beam, which then passes down the middle of a wire helix that stretches the length of the tube, finally striking a collector at the other end.
TWTs are commonly used as amplifiers in satellite transponders.
They are also used extensively in radar, particularly in airborne fire-control radar systems, and in electronic warfare and self-protection systems. Typically a control grid is introduced between the electron gun and the slow-wave structure to allow pulsed operation.