A package-type travelling-wave amplifier with a new magnetic focusing system

Details of the construction and design procedure of a new magnetic focusing system are described, followed by an explanation of the newly-developed package-type travelling-wave amplifier type 8W76. The focusing system of the 8W76 consists of three parts, i.e. a magnetic lens located between the helix and the electron gun, the conventional periodic magnetic field structures and the new magnetic circuits to compensate the discontinuous section of the magnetic field due to the existence of the output waveguide of the amplifier. Peak magnetic flux densities of about 650 gauss are obtained. With this focusing system the saturated power output of between 6 and 10 watts and a small-signal gain of between 33 and 36 dB are obtained for the frequency range 6¿7.5Gc/s.