Additive Manufacturing for Linear Accelerators Workshop

30 Jul 2025, 19:30 → 1 Aug 2025, 18:00 Europe/Berlin

02.201a/b (Goethe University Frankfurt am Main)

Hendrik Hähnel (Goethe University Frankfurt, Institute for Applied Physics), Michael Mayerhofer (Universität der Bundeswehr München)

Welcome to AM 4 Linacs, a workshop dedicated to exploring how additive manufacturing (AM) can support and advance linear particle accelerators. Taking place on July 31 and August 1, 2025, this event brings together researchers, engineers, students, and industry professionals to discuss current advancements, challenges, and opportunities in this exciting field. Whether you’re experienced with AM, just starting to explore its potential, or simply curious, this workshop offers a welcoming space to connect, share ideas, and learn together. We encourage everyone, including students with an interest in AM and linacs, to join the workshop. 

We are looking forward to meeting you!

Hendrik Hähnel & Michael Mayerhofer

Workshop Partners:

AM4Linacs preliminary program - 2025-07-11.pdf

Wednesday 30 July

19:30 Arrival Meet-Up

Details TBD

Thursday 31 July

Thursday Morning: Welcome & Introduction

1 Welcome by Organizers

Speakers: Hendrik Hähnel (Goethe University Frankfurt, Institute for Applied Physics), Michael Mayerhofer (Universität der Bundeswehr München)

Thursday Morning: Talks

2 Title TBD

Speaker: Udo Weinrich (GSI)

3 TBD

Speaker: TBD TBD

4 Additive Manufacturing for Particle Accelerators and Storage Rings at GSI and for FAIR

The booming additive manufacturing technology has been used in our daily lives as well as in scientific research. The RACE (Resonators Additively Constructed for Experiments) team initiated by the Stochastic Cooling Group (SCO), GSI, is worldwide one of the first teams working on the application of this technology for the R&D of particle accelerators and storage rings. Additive manufacturing can overcome many of the limitations of traditional manufacturing methods, so it allows designing novel accelerators and storage rings. Some ongoing activities at GSI and for FAIR will be introduced.

Speaker: Dr Chuan Zhang (GSI)

5 The peculiar structure of metals built by additive manufacturing and their implication on properties of interest for accelerator science and technology

The contribution is aimed at discussing the solidification mechanisms of metal parts produced by Additive Manufacturing (AM), especially focussing on Laser Powder Bed Fusion technology (L-PBF). The typical microstructure, surface features and possible defects are analysed to highlight expected differences with respect to part produced by traditional routes.

Speaker: Maurizio Vedani (Politecnico di Milano)

6 Additive Manufacturing of GHz RF Cavities from Pure Copper

Our research focuses on exploitation the potential of AM for S- and C-band RF cavities made from pure copper.Prototypes of a 5-cell S-band drift tube resonator and side-coupled cavity cells, commonly used in linac systems for medical and industrial applications, have been successfully additively manufactured. Evaluation of these prototypes reveals that AM cavities perform comparably to conventionally manufactured in terms of e.g. vacuum tightness, geometric accuracy and surface conductivity. Simultaneously, AM allows for a major cost reductions and increased shunt impedance.
Our results highlight the potential of AM in RF cavity fabrication and, consequently, performance improvements for linacs.

Speaker: Michael Mayerhofer (Universität der Bundeswehr München)

7 Thoughts on Additive Manufacturing of H-Type DTL components

Experience on AM produced accelerator components have been made since quite a few years and the community can now build on the numerous insights and results from these projects. This contribution will draw conclusions with respect to H-mode drift tube structures and make some suggestions for possible next steps. Some related beam dynamics studies will check which drift tube arrays are reasonable at some typical beam energies and beam currents.

Speaker: Ulrich Ratzinger (Goethe - Universität Frankfurt)

12:00 Lunch (included)

Thursday Afternoon: Talks

8 First Beam Test of an Additively Manufactured H-Mode Linac Structure made from Pure Copper

We present succesful beam tests of an additively manufactured IH-Type linac structure with a 1.4 MeV beam from an Van de Graaff accelerator.

Speaker: Hendrik Hähnel (Goethe University Frankfurt, Institute for Applied Physics)

9 Research on Additive Manufacturing Technology for Compact Radio Frequency Quadrupole Design and Production

This work presents the development of additive manufacturing (AM) technology for the design and production of compact Radio Frequency Quadrupole (RFQ). Using PBF-LB/M with Cu-ETP material, the study focuses on advanced supportless design, cost-efficient manufacturing, and improved cooling performance. The research also covers AM post-processing, metrology, and validation for next-generation accelerator applications.

Speaker: Guntis Pikurs (Riga Technical University)

10 Development and test of a compact RF coupler utilizing additive manufacturing

Additive manufacturing (AM) has proven to be a powerful technique for rapid prototyping and the fabrication of complex geometries. For use in a 433 MHz IH-DTL cavity, a CF40 coupler was developed and manufactured from high-purity copper using a 3D printing process. It incorporates a water-cooling concept that would be impossible to implement using conventional manufacturing methods. The coupler features a ceramic window water cooled on both sides, an outer conductor with spiral cooling channels, and a water cooled inner conductor. Optimal power transmission is frequency-dependent and is fine-tuned by adjusting the inner conductor geometry through CST simulations. Initial tests were carried out to condition the Franz-IH at power levels of up to 10 kW continuous wave (CW).

Speaker: Jan Dominik Kaiser (IAP Goethe University Frankfurt a.M.)

11 Additive Manufacturing of Copper and Copper Alloys with Green Lasers

Speaker: Samira Gruber

12 Plasma Electrolytic Polishing: A High-Performance Surface Finishing Technique for SRF and AM Applications

Plasma Electrolytic Polishing (PEP) is gaining increasing attention as a highly efficient surface treatment method, offering significant advantages over traditional polishing techniques. In several industrial sectors, PEP has already been fully integrated into commercial solutions; in others, it is still emerging as a promising alternative.

At INFN-LNL, PEP has been under continuous development since 2019, particularly within the context of Superconducting Radio Frequency (SRF) applications. These include resonant cavities and other components that require exceptional surface quality to maximise performance. The initial motivation for exploring PEP stemmed from the desire to eliminate hazardous chemicals such as hydrofluoric acid (HF), typically used in electropolishing of niobium (Nb), a key material in SRF technology.

Beyond its "greener" chemistry, PEP has demonstrated remarkable polishing rates and outstanding surface levelling capabilities. Moreover, recent work at LNL has shown strong compatibility - and in some cases even synergy - between PEP and surfaces produced via Additive Manufacturing (AM). This positions PEP as a potential all-in-one finishing technique, eliminating the need for multiple post-processing steps such as mechanical polishing.

This contribution will present the fundamentals of PEP and share insights from LNL’s experience applying this technique to both conventionally manufactured and AM substrates. Complementary results will also be presented in a separate talk by Tochukwu Emmanuel, highlighting our group's latest findings. Performance benchmarks, current challenges, and the prospects for full integration of PEP into AM workflows will be discussed.

Speaker: Eduard Chyhyrynets (INFN LNL)

15:05 Coffee Break

Thursday Afternoon: Talks

13 Low-Level Tests for a 3D-Printed 704.4 MHz CH Cavity

Speaker: Eduard Boos

14 Optimisation of drift tube cooling and drift tube geometries of an additive manufacturing IH-type cavity

Additive manufacturing (AM) has become a powerful tool for rapid prototyping and manufacturing of complex geometries. A 433 MHz IH-DTL cavity has been constructed to act as a proof of concept for direct additive manufacturing of linear accelerator components. The original design of the cooling for the drift tube showed insufficient heat dissipation, leading to potential thermal deformation during operation. To address this issue, a detailed optimization of the cooling system was performed, incorporating advanced thermal simulations and iterative design improvements.
Additionally, the drift tube geometries were refined to enhance mechanical stability and thermal efficiency while maintaining the required electromagnetic properties. The results demonstrate that additive manufacturing enables significant design flexibility, allowing for innovative solutions to thermal management challenges in high-frequency linear accelerator components.

Speaker: Benjamin Dedic (Goethe Universität Frankfurt)

15 Additive manufacturing of water-cooled drift tubes and stems for H-type cavities

H-type structures are a dedicated candidate for cw operation because they can be cooled very efficiently. With the aid of additive manufacturing, in particular complicated and complex water-cooling channels inside stems and drive tubes can be realized. In a relatively small cw operated H-type buncher cavity with only a length of 540 mm and a diameter of 614 mm, rf power levels up to 24 kW were easily realized in long time performance.

Speaker: Holger Höltermann (BEVATECH GmbH)

16 TBD

17 TBD

18 TBD

19:00 Workshop Dinner (included)

Friday 1 August

Lab Tour: Frankfurt Neutron Source (FRANZ)

Friday Morning: Talks

19 KIT-IBPT / Technik - Kurzportrait

Eine kurze Vorstellung über uns und unser Institut.
Woher kommen wir?
Womit beschäftigen wir uns?

Speaker: Till Borkowski (KIT - IBPT)

20 Title TBD

Speaker: Julius Storch (IAP Frankfurt)

21 Recent Advances in Plasma Electrolytic Polishing of AM Components @INFN

Additive Manufacturing (AM) has opened new frontiers in the fabrication of complex components for accelerator applications. However, the surface roughness of as-built parts remains a key challenge, particularly for high-frequency RF and vacuum environments. Plasma Electrolytic Polishing (PEP) is emerging as a promising post-processing technique to address this issue.

PEP is an electrochemical technique that uses high voltage (250–350 V) and moderate current densities in heated electrolytes to polish metallic surfaces. A key feature of the process is the formation of a vapour-gas layer at the anode surface, which enables efficient and uniform material removal without mechanical contact. The result is a smooth, reflective finish, with typical material removal rates between 4 and 30 μm/min.

The PEP operates by immersing the component - configured as the anode - into a heated electrolyte bath maintained at approximately 60-90°C. A dynamic formation of a vapor-gas layer (VGL) around the part plays a fundamental role, resulting in a dramatic reduction in roughness and a highly reflective, mirror-like surface finish.

At INFN-LNL, we have applied PEP to a variety of AM-fabricated materials and geometries relevant to accelerator technology. In this contribution, we report on the most recent experimental results obtained from the PEP treatment of benchmark stainless steel samples, inner copper conductors, and copper drift tubes designed for LINAC structures.

Speaker: Tochukwu Emmanuel Ezeaba (Istituto Nazionale Di Fisica Nucleare (INFN), Legnaro (PD), Italy)

22 Dielectric Properties of 3D Printed Polymers for RF Applications at 500 MHz

To determine the relative permittivity $\epsilon_r$ and the dielectric loss factor $\tan(\delta)$ of 3D printed polymers at 500$\,$MHz a test cavity was built. When a dielectric material is inserted, the frequency and the quality factor of the cavity change. A comparison of the measured data with simulations yields the values of $\epsilon_r$ and $\tan(\delta)$. This allows the use of these 3D printed polymers in RF applications such as couplers.

Speaker: Philipp Müller (Goethe Universität Frankfurt)

23 Utilizing Additive Manufacturing for Beam Diagnostics Applications and Radiation Shielding

Besides beam characterization, cameras at our institute are also applied to acquire multipacting and cavity glowing effects during conditioning. To support these applications, additive manufacturing provides a fast, cost-effective, and flexible method for developing custom camera mounts precisely conformed to their specific positions, whether inside or outside a cavity.
In addition to its applications in the fabrication of camera mounts, additive manufacturing offers the capability to produce a radiation shielding enclosure using tungsten-filled filament (Prusament, PETG Tungsten 75%) for a camera installed inside a cavity. This shielding is utilized during the conditioning. Its effectiveness is assessed by comparing the resulting images with those obtained from an unshielded camera under equivalent conditions.

Speaker: Leonie Bauer (Goethe University Frankfurt, Institute for Applied Physics)

12:00 Lunch (included)

Discussions: Current Challenges

14:00 Coffee Break

Discussions: Organization & Strategy