Monolithic Additive Manufacture of Lower Hybrid Current Drive Launchers

Additive Manufacture (AM) of Radio Frequency (RF) launchers is an emerging technique in the field of fusion power, where flexibility of AM is a key enabling technology for rapid production of complex RF geometries with integrated cooling channels unachievable by conventional machining. Several past limitations in AMed copper alloys, including mechanical properties, surface roughness, and internal voids, have limited their use in RF and vacuum applications. We present a Lower Hybrid Current Drive (LHCD) launcher produced through AM, Micro-Computed-Tomography studies of and techniques to address internal voids with Hot Isostatic Pressing (HIPing), and Chemical-Polishing (CP) and Chemical-Mechanical-Polishing (CMP) of internal surface roughness in areas without mechanical access. RF properties of pentagonal and hexagonal waveguides to allow design of self-supporting overhangs in AMed RF structures are discussed. Advances in AM and materials demonstrated by construction of an AMed HFS LHCD launcher provide future pathways for monolithic AM of complete launcher assemblies. We discuss monolithic launcher designs and the results of early production tests. Work supported by US DOE under DE-FC02-04ER54698 and DE-SC0014264.