Optimizing Lattice-Based Rafts for Distortion Mitigation in a GRCop-42 Laser Powder Bed Fusion Additive Manufactured Lower Hybrid Current Drive Launcher Utilizing Resin Based SLA Analogues

Laser Powder Bed Fusion (L-PBF) is a key enabling technology for rapid Additive Manufacturing (AM) of complex part geometries unachievable with traditional manufacturing techniques. AM of a high field side (HFS) lower hybrid current drive (LHCD) launcher was successfully demonstrated using Laser Powder Bed Fusion (L-PBF) of Glenn Research Copper 84 (GRCop-84). Coefficient of thermal expansion (CTE) mismatch between GRCop-84/42 and steel or Inconel build plates resulted in modest, though measurable, warping. Support structures called rafts provide a platform to decouple thermal stresses at the build-plate-component interface. An LCD-based stereolithography (SLA) photopolymer resin printer was used to rapidly optimize raft designs using a low-cost platform. Contraction of the photopolymer during curing produced volumetric reduction driver strain analogous to CTE-mismatch strain during LPBF. Raft geometries comprised of a lattice of cones, hexagons, triangles, and squares were optimized to minimize build-plate curvature. Raft solutions found with SLA to minimize build plate curvature and improve accuracy will be implemented in future L-PBF trials to reduce warping due to thermal stress.