Miniature TWTs with optimized efficiency and broadband phase characteristics

A family of miniature 10 watt traveling wave tubes has recently been developed by Varian. These tubes have one fifth the volume of conventional traveling wave tubes and are small enough to fit inside X-band waveguide. The key to achieving the small size of these miniature tubes is the use of samarium cobalt focusing magnets. The high magnetic field which can be obtained from samarium cobalt allows the miniature tube to be designed at much higher current and lower voltage than conventional tubes, and in this way the length of the tube is reduced to about one half that of a conventional tube. The magnet diameter is reduced because of the high field strength of the magnets.