LASER FINE PIPE

PURPOSE:To realize high temperature resistance without using a beryllia ceramics by joining a thin alumina ceramic pipe into a metal pipe and by joining doughnut ceramic plates to both ends of the metal pipe. CONSTITUTION:An outer peripheral surface of an alumina ceramic pipe 1 and an inner side of a metal pipe 2 are joined and fixed by brazing, etc. Doughnut ceramic plates 3, 3' are also brazed to both ends of the pipe 2. Unbrazed end sides of the ceramic plates 3, 3' are insulated electrically each other. The outer diameter of the ceramic plates 3, 3' is the same as that of the pipe 2, and the inner diameter is smaller than the outer diameter of the pipe 1 and larger than the inner diameter of the pipe 1. Since a wall thickness of a fine pipe is small and a metal of good heat conductivity is applied to the circumference thereof, heat generated inside the fine pipe is conducted form an alumina section to a metal section, and then diffused thereby realizing radiation effect which is equivalent to that in case beryllia ceramics is used.