Efficient operation of a high-power X-band traveling wave tube amplifier

We report experimental results demonstrating 54% power conversion efficienc y (43% energy conversion efficiency), from a two-stage X-band traveling wav e tube amplifier designed for high-power operation. The first stage of the amplifier is a 12-cm-long Boron Nitride dielectric section used to modulate the electron beam. The second stage consists of a long high-phase-velocity bunching section followed by a short low-phase-velocity output section. Ou tput powers of up to 78 MW with narrow spectrum width were obtained with si milar to 700 kV, similar to 200 A beam. (C) 1999 American Institute of Phys ics. [S0003-6951(99)02642-X].