Assembly of an Additive Manufactured GRCop-84 Copper Alloy Lower Hybrid Current Drive Launcher Antenna with Pulsed 1070 nm Fiber Laser Welding

Build volume limitations require AM of modular segments that are joined together with laser welding. A fixturing system was developed to align and compress 0.5 mm thick butt weld joints, shield internal surfaces with argon gas, and prevent distortion during assembly.

An external fixture and clamping plate align launcher sections while providing beam access for a pulsed 1070 nm fiber laser, while an internal micro-jack expands within the waveguide segments eliminating height offset between joining sections and distributing argon shield gas. Conduction mode welding prevents keyhole formation and beam penetration into the waveguide interior, eliminating spatter and producing a smooth bottom weld bead.