| 摘要 |
PURPOSE:To obtain a discharge tube having strong thermal impact resistance by composing a plasma discharge tube of a cylindrical outer tube and a cylindrical inner tube made of a plurality of divided elements. CONSTITUTION:A plasma discharge tube is composed of a cylindrical outer tube 8 formed of alumina fine ceramics, and a cylindrical inner tube 9 slidably engaged within the tube 8, and the tube 9 is composed of a plurality of divided elements 9a divided axially at a predetermined interval. The elements 9a are made of sintered boron nitride being one type of fine ceramics. In addition to the boron nitride, aluminum oxide or nitride is used, and they have strong resistance to a thermal strain similarly to the boron nitride, with preferable electric insulation. Engaging steps 10, 11 to be engaged in a radially superposed state with the opposite ends of other divided elements 9a are formed at both right and left ends of the elements 9a, and the elements 9a are slidably and removably inserted into the tube 8 in the state being engaged with each other. |
