Joining of ceramic tubes using a high-power 83-GHz Millimeter-wave beam

High purity, high density alumina tubes have been successfully joined using a high-power millimeter-wave beam. This technique exploits the use of the beam-forming capability of an 83-GHz gyrotron-based system allowing the deposition of energy into a narrow region surrounding the joint area with minimal heating (<100°C) of the metal fixturing (a modified microlathe). The power deposition and heating was modeled using a closed form analytical approach that has been compared with experimental results. The modeling results indicated areas of improvement that were implemented to make the process more effective. Conjoined tubes resulting from this technology meet the requirements for the dielectric-loaded accelerator (DLA) being developed by the Argonne National Laboratory.