Effect of Ir on the emission property of Ba dispenser cathode

Ba dispenser cathode is the widely applied thermionic cathode at present. In order to improve the emission property of the cathode to meet the requirement for the high power vacuum electron devices, Ir was added in the dispenser cathode. It is found that the emission property could be improved after adding Ir since it enhances charge transfer from Ba to O and further stabilizes the interface configuration of Ba-O-W-Ir. It is also found that the composition of the surface layer change with the activation and operation time. IrW in the cathode would benefit for the improvement of the cathode performance.