Annealing temperature and property of Hf used for FWG-TWT

After fully considering working environment of electron gun grid cathode, Hf-grids were annealed at 800, 900, 1000 in vacuum. Microstructure and texture of the Hf-grids were studied by means of SEM, MRD and Schulz technology. In order to compare the property of Mo with Hf, Mo and Hf were respectively deposited onto the surface of the cathode by ion beam assisted deposition for imitating the surface conditions of Mo-grids and Hf-grids, the cathode was fabricated by Ba-W materials. The capability of restraining electron emission was evaluated by measuring the ratios of thermo-electronic emission and secondary electron emission coefficient on testing system. The results show that crystallinity and grain size increase and fiber structure decreases with increasing annealing temperature. The optimality temperature is 900. It is found that Hf can effectively restrain the electron emission. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.