PRACTICAL DESIGN OF RESONANCE FREQUENCY TUNING SYSTEM FOR COAXIAL RF CAVITY FOR THERMIONIC TRIODE RF GUN

A prototype of coaxial rf cavity for thermionic triode rf gun has been fabricated and tested at low power. The low power test reveals the dependency of cavity resonance frequency on cavity and cathode temperature. Another critical point for resonance frequency is the cavity length. Inaccuracies in machining or simulation of cavity length cause errors in resonance frequency of manufactured cavity. In order to compensate for undesired resonance changes a tuning mechanism has been installed for the prototype of coaxial rf cavity. In this paper we present the capability of the stub tuning system and propose a modified coaxial rf cavity design.