A 3D Printed Copper Radio Frequency Quadrupole (RFQ) Component for the Large Hadron Collider

CERN, or the European Organization for Nuclear Research, currently houses the world’s largest particle accelerator. Called the Large Hadron Collider (LHC), its objective is to transmit energy to particles through electric or magnetic fields. Today, we bring your attention to the LHC because it could include for the first time a 3D printed copper radio frequency quadrupole. Specifically, this is a radio frequency quadrupole linear accelerator (RFQ), one of the most difficult parts to design and assemble. For these reasons, Fraunhofer IWS, in collaboration with CERN, the Technical University of Riga and the Polytechnic University of Milan, chose additive manufacturing, or more specifically laser powder bed fusion, to produce it.

The partners all part of the I.FAST (Innovation Fostering in Accelerator Science and Technology) Horizon 2020 project, which is funded by the European Union and aims to develop new particle accelerator designs. With 49 partners, it hopes to accelerate innovation in a subject that can be quite challenging. It is in this context that metal additive manufacturing has been used, a new concrete example of the technology’s potential.

The classic model of a complete quadrupole (photo credits: CERN)

Additive manufacturing for overcoming assembly problems

According to the project partners, the RFQ is traditionally manufactured from highly conductive materials and alloys, via multi-axis milling of “prefabricated large-scale-forged single-piece components”. In concrete terms, the RFQ integrates 4 modules that are assembled by furnace brazing. However, the latter generally releases residual stresses, which can lead to geometric distortion. Several heat treatments during machining are then necessary to maintain the quality level and ensure the proper functioning of the part. As you can imagine, all these steps are time-consuming, costly and not very efficient. To overcome this, the project partners turned to additive manufacturing, particularly because of its ability to produce components in a single block, thus avoiding the assembly steps and their constraints.