Red and Green Laser Powder Bed Fusion of Pure Copper in Combination with Chemical Post-Processing for RF Cavity Fabrication
Michael Mayerhofer,
Stefan Brenner,
Marcel Dickmann,
Michael Doppler,
Samira Gruber,
Ricardo Helm,
Elena Lopez,
Verena Maier,
Johannes Mitteneder,
Carsten Neukirchen,
Vesna Nedeljkovic-Groha,
Bernd Reinarz,
Michael Schuch,
Lukas Stepien,
Günther Dollinger
Affiliations
Michael Mayerhofer
Institute for Applied Physics and Measurement Technology, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Stefan Brenner
Institute for Design and Production Engineering, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Marcel Dickmann
Institute for Applied Physics and Measurement Technology, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Michael Doppler
RENA Technologies Austria GmbH, Samuel-Morse-Straße 1, 2700 Wiener Neustadt, Austria
Samira Gruber
Institute for Material and Beam Technology IWS, Fraunhofer Society, Winterbergstraße 28, 01277 Dresden, Germany
Ricardo Helm
Institute for Applied Physics and Measurement Technology, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Elena Lopez
Institute for Material and Beam Technology IWS, Fraunhofer Society, Winterbergstraße 28, 01277 Dresden, Germany
Verena Maier
Center for Applied Sciences and Tissue Engineering and Regenerative Medicine, Munich University of Applied Sciences, Lothstrase 34, 80335 Munich, Germany
Johannes Mitteneder
Institute for Applied Physics and Measurement Technology, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Carsten Neukirchen
Institute of Chemical and Environmental Engineering, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Vesna Nedeljkovic-Groha
Institute for Design and Production Engineering, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Bernd Reinarz
Innovation Center Düsseldorf, EOS GmbH Electro Optical Systems, Fichtenstr. 53, 40233 Düsseldorf, Germany
Michael Schuch
Bundeswehr Research Institute for Materials, Fuels and Lubricants (WIWeB), Institutsweg 1, 85435 Erding, Germany
Lukas Stepien
Institute for Material and Beam Technology IWS, Fraunhofer Society, Winterbergstraße 28, 01277 Dresden, Germany
Günther Dollinger
Institute for Applied Physics and Measurement Technology, University of the Bundeswehr Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
Linear particle accelerators (Linacs) are primarily composed of radio frequency cavities (cavities). Compared to traditional manufacturing, Laser Powder Bed Fusion (L-PBF) holds the potential to fabricate cavities in a single piece, enhancing Linac performance and significantly reducing investment costs. However, the question of whether red or green laser PBF yields superior results for pure copper remains a subject of ongoing debate. Eight 4.2 GHz single-cell cavities (SCs) were manufactured from pure copper using both red and green PBF (SCs R and SCs G). Subsequently, the surface roughness of the SCs was reduced through a chemical post-processing method (Hirtisation) and annealed at 460 °C to maximize their quality factor (Q0). The geometric accuracy of the printed SCs was evaluated using optical methods and resonant frequency (fR) measurements. Surface conductivity was determined by measuring the quality factor (Q0) of the SCs. Laser scanning microscopy was utilized for surface roughness characterization. The impact of annealing was quantified using Energy-Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction to evaluate chemical surface properties and grain size. Both the SCs R and SCs G achieved the necessary geometric accuracy and thus fR precision. The SCs R achieved a 95% Q0 after a material removal of 40 µm. The SCs G achieved an approximately 80% Q0 after maximum material removal of 160 µm. Annealing increased the Q0 by an average of about 5%. The additive manufacturing process is at least equivalent to conventional manufacturing for producing cavities in the low-gradient range. The presented cavities justify the first high-gradient tests.