  Continuous developments in Additive Manufacturing (AM) technologies are
opening opportunities in novel machining, and improving design alternatives for
modern particle accelerator components. One of the most critical, complex, and
delicate accelerator elements to manufacture and assemble is the Radio
Frequency Quadrupole (RFQ) linear accelerator, used as an injector for all
large modern proton and ion accelerator systems. For this reason, the RFQ has
been selected by a wide European collaboration participating in the AM
developments of the I.FAST (Innovation Fostering in Accelerator Science and
Technology) Horizon 2020 project. RFQ is as an excellent candidate to show how
sophisticated pure-copper accelerator components can be manufactured by AM and
how their functionalities can be boosted by this evolving technology. To show
the feasibility of the AM process, a prototype RFQ section has been designed,
corresponding to one-quarter of a 750 MHz 4-vane RFQ, which was optimised for
production with state-of-art Laser Powder Bed Fusion (L-PBF) technology, and
then manufactured in pure copper. To the best knowledge of the authors, this is
the first RFQ section manufactured in the world by AM. Subsequently,
geometrical precision and surface roughness of the prototype were measured. The
results obtained are encouraging and confirm the feasibility of AM manufactured
high-tech accelerator components. It has been also confirmed that the RFQ
geometry, in particular the critical electrode modulation and the complex
cooling channels, can be successfully realised thanks to the opportunities
provided by the AM technology. Further prototypes will aim to improve surface
roughness and to test vacuum properties. In parallel, laboratory measurements
will start to test and improve the voltage holding properties of AM
manufactured electrode samples.
