CATHODE HEATER HEATED INDIRECTLY

摘要

The heater has a primary winding (4) formed with the ratio of outer diameter of the molybdenum mandrel (3) to the diameter of the tungsten core wire (2) being set at 4.3 to 6.0. Winding strain due to compressive stress is applied to the inward of the winding direction and tensile stress is applied to the outward of the winding direction of the tungsten core wire while the tungsten core wire is wound around the molybdenum mandrel. The winding is substanitally circular and the largest inner diameter of the winding is 4.3 to 6.0 times the diameter of the core wire over the entirety of the winding.