Pulsed, high perveance, high power klystrons for linear accelerators

In this paper are described two models of 4-cavity klystrons respectively designed for 5 and 20 megawatts peak power. Perveances of 2.7 and2 \times 10^{-6}and beam impedance of 1000 ohms result in low voltage operation and various corresponding advantages: low cost of modulators, easier insulation and X-ray protection, non-critical tuning of low loaded Q cavities. The same technology is used for both models: massive construction of (water-cooled) walls and cavities, fastening with removable, bakable joints of gun, collector, input and output circuit, and titanium pump, proper design of gun assembly, shielding of output window, output at the top, removable focusing coils. Such features have given practical solutions to many problems: fixed tuned cavities and negligible thermal power drift, no gun oscillation, operation under vacuum on both sides of the window as required for accelerators, control of components, reproductibility of performance, long life, recovering at low cost. The incorporated titanium pump allows the tubes to be operated sealed off under automatic vacuum control.