Efficiency improvements on IOTs

This paper discusses the measures for efficient improvement on IOTs (inductive output tubes), and the trend of power increase with time. For analog TV, the average power varies substantially with picture content and standard. CW operation benefits of much better efficiencies because linearity and bandwidth are not needed. Enhancing beam efficiency was obtained by two ways: 1) better design of the gun and the output circuit. 2) use of depressed collectors, in which the electrons travel through retarding electric field and eventually fall on a collector with very little kinetic energy left. The different collectors are energized at various high voltage levels, calling for insulating cooling medium.