Arc-plasma deposited dispenser cathode for use in powerful flow water vacuum electron heater

摘要

A principal new design of vacuum electron heater is presented. The vacuum electronic heater (VEH) is developed as a vacuum diode and contains a thermionic cathode and an anode. The anode is cooled by flowing water. The thermonic dispenser cathode heated by tungsten heater emits an electron current. Kinetic energy of the electrons accelerated by the supply-line voltage of the anode is transformed to the anode heat. Therefore the flow water in the jacket is heated. Smooth control of output power is provided by variation of working temperature of the dispenser cathode in range of from 700 up to 1000/spl deg/C. Cathode is located in vacuum volume on the legs and hermetically fastened in an insulator. The cathode of VEH has form of cylinder with outer diameter of 22-24mm and height of not less than 100mm. Porous tungsten matrix with thickness of 0.5-0.7mm is built on the surface of molybdenum cylinder by arc-plasma deposition method. The matrix is impregnated by emission substance with composition of 3BaO-CaO-Al/sub 2/O/sub 3/ and then the emitting surface is formed by mechanical treatment to get needed dimensions. During VEH operation current density on the cathode emission surface isn't higher than IA/cm/sup 2/.