Future Directions of Monolithic Additive Manufactured LHCD Launchers in DIII-D

Additive Manufacture (AM) of Radio Frequency (RF) launchers is a key enabling technology for rapid production of complex RF geometries unachievable by conventional machining. HFS LHCD launchers currently installed on DIII-D were AMed in segments due to build volume restrictions when using Laser Powder Bed Fusion (L-PBF). Increased build volume now enables launchers to be printed as a monolithic structure, reducing build time and cost. With the majority of manufacturers transitioning from GRCop-84 to GRCop-42 used in the monolithic AMed launcher, re-development of Chemical-Polishing (CP) and Chemical-Mechanical-Polishing (CMP) of internal surface roughness in areas without mechanical access was required. Improvements in polishing techniques now enable AMed GRCop-42 surfaces to be used in RF systems. RF measurements of monolithic AMed structures were compared to those of segmented AMed structures to validate dimensional accuracy of the L-PBF and CP/CMP polishing processes. Raft geometries to reduce CTE based bowing of build plates and deformation of components are discussed. Development of novel reduced-activation copper alloys are proposed to eliminate the niobium in current GRCop alloys to mitigate high level waste generation.