Studying the effect of annealing temperature on Hf and characteristic of restraining electron emission

摘要

Hf acted as grid is used for grid-control TWT in order to restrain or eliminate electron emission.900 °C ,1000 °C ,1100 °C was selected as annealing temperature considering environment of cathode.Microstructure, texture and pole map were studied using SEM,MRD and Schulz technology.The results show crystallinity and grain size increased and fiber structure decreased with annealed temperature increasing.The optimality microstructure and mechanical properties are obtained at 900 °C.Mo and Hf were respectively deposited onto the surface of cathode by ion beam assisted deposition for imitating the surface conditions of Mo-grids and Hf-grids, the cathode is fabricated by Ba-W materials.The capability of restraining electron emission is evaluated by measuring the ratios of thermo-electronic emission and secondary electron emission coefficient on testing system, it is showed that Hf can effectively restrain the electron emission.