Gyrotron traveling wave amplifier with a helical interaction waveguide

A new microwave system in the form of a cylindrical waveguide with a helica l corrugation of the inner surface is proposed for a gyrotron traveling wav e tube (gyro-TWT). The corrugation radically changes the wave dispersion in the region of small axial wave numbers. This allows significant reduction in the sensitivity of the amplifier to the electron velocity spread and an increase in its frequency bandwidth. An X-band gyro-TWT operating at the se cond cyclotron harmonic with a 200-keV, 25-A electron beam produced an outp ut power of 1 MW, corresponding to a gain of 23 dB and an efficiency of 20% .