J. Boykin, R. Shealy
REM Surface Engineering,
United States
Keywords: additive manufacturing, postprocessing, surface finishing, copper, GrCOP-42
Summary:
In a reactor environment, plasma material interaction (PMI) issues associated with radio frequency (RF) coupling structures are similar to those for the first wall and have been identified as a potential problem. A primary challenge is to obtain high power, breakdown resistant density couplers with low loss compatible with fusion plasmas. Advanced manufacturing techniques, i.e. additive manufacturing (AM), along with AM specific Copper alloy GrCOP-42, enable optimized RF structures to improve coupler performance; however, as-printed AM metal surfaces contain numerous surface and near-surface defects which can reduce performance and/or serve as failure points. A post-process surface finishing technique is required to facilitate successful AM implementation. REM addressed the PMI issues associated with RF coupling structures by utilizing additive manufacturing to maximize the benefits of AM specific alloys that, we believe, are optimized for these uses/environments. In order to fully realize the potential of the AM alloys, components must be surface finished. It is expected that the planarized and smoothed surfaces of the components will optimize the performance of the AM RF components, thus increasing the expected life and efficiency of the reactor, while potentially lowering its total lifecycle costs. The plasma fusion market is currently theoretical, making its exact size challenging to define. The ultimate goal of fusion reactors, such as SPARC and ARC, is to replace fossil-fuel-driven power plants. With the global steam turbine market valued at $24.1 billion in 2019, the potential value of RF component surface finishing for fusion reactors could conservatively range from $1 to $20 million. Initial customers would likely include government-sponsored and university-led plasma fusion projects, as no commercial fusion reactor producers exist yet. Traditional turbine manufacturers may eventually enter this market. Beyond plasma fusion, GRCop alloys are gaining traction in the rocket propulsion industry for combustion chambers and liners. Valued at $4.23 billion in 2018, the rocket propulsion market presents significant opportunities. Combustion chambers made with GRCop alloys cost $35,000–$50,000 each, and commercial rockets typically require 10–20 such components, potentially generating over $150,000 per rocket for advanced polishing processes. Early adopters of GRCop alloys include both public and private rocket propulsion companies, with more expected as performance data improves. Additional applications for GRCop alloys include satellite waveguides and medical devices like magnetic imaging systems, provided effective polishing processes are developed to optimize their internal surfaces.