Dual anode electron gun for Ka-Band helix TWT

A dual anode convergent electron gun of perveance 0.14 mup has been designed for Ka-Band helix Traveling Wave Tube (TWT) which would ultimately have application in satellite communications. Gun has been designed using codes EGUN, TRAK & OMNITRAK. Pierce type electron gun with isolated beam forming electrode (BFE) & M-Type dispenser cathode with 3.1 mm button diameter has been opted. It consists of two isolated anodes to meet the requirement of long life & high reliability. Initially, in cathode selection, life considerations are ignored, the gun is designed with available cathode. Periodic Permanent (PPM) focusing has been designed using Sm₂Co₁₇ high intensity magnet in order to reduce the size & weight of the overall TWT. Confined flow beam focusing has been adopted. A compact small size electron gun assembly has been designed using ceramic insulator & suitable support structure. High voltage analysis has been carried out using code ESTAT. This paper presents the approach for overall design of gun assembly with dual anode.