Optimisation of Pierce type convergent electron gun for gain and phase matched miniature helix TWTs

Pierce type convergent electron guns are the only choice for helix travelling wave tubes (TWT) The authors present a re-optimization of the gun geometry through intensive theoretical and experimental studies. This includes the study of the variation in various sensitive geometrical parameters like (i) axial gap between cathode and anode Z/sub ac/, (ii) axial position of the beam forming electrode (BFE) with respect to cathode Z/sub cb/, (iii) radial gap between cathode and BFE R/sub cb/, (iv) other parameters like BFE angle, BFE hat height, anode hole radius etc.