| 摘要 |
PURPOSE:To stabilize the emission of thermion by forming a complex oxide layer consisting of a thermion emissive oxide and oxide of W on a cathode base consisting of Ni-W alloy free from any reducing agent, and further forming a thermion emissive oxide layer on it. CONSTITUTION:A cathode structure constituted with a plate 5 and leg 4 is formed by punching an alloy consisting of 20-30% by weight of W and residual amount of Ni and contains no reducing agent. Then, (Ba,Sr,Ca)CO3 is blasted on the plate, which is sealed in an electron tube, and the base metal is heated by sending a current directly while it is being evacuated, thereby (Ba,Sr,Ca)CO3 is burnt to (Ba, Sr,Ca)O and a thermion emissive oxide layer 3 is formed. Then, simultaneously a complex oxide (Ba,Sr,Ca)3WO6 layer 6 consisting of oxide of thermion emissive oxide and oxide of W in the base is formed in the interface between the base and the emissive layer. Thus the thermion emission characteristics can be stabilized over a long period. |
