Additive Manufacturing (AM) has the potential to increase the performance of radio frequency (rf) cavity resonators while cutting manufacturing costs. To leverage this potential, AM processes and potentially post-processing techniques must be tailored to cavity requirements. Additionally, conventional manufacturing's quality assurance methods must adapt to the AM case requiring numerous studies on additively manufactured test bodies. We introduce a compact rf cavity design, enabling cost-effective and precise studies of the surface conductivity of test bodies. The test body is mounted on a dielectric holder inside a cylindrical rf cavity made of aluminum. The geometry of the test body corresponds to a rod which allows simple and cost-effective production, post-processing and evaluation. The test body’s surface conductivity is extracted from a measurement of the quality factor (Q0) of the cavity. Depending on the geometry of the test body, Q0 values of over 10,000 can be achieved for copper test bodies. Thereby, the test body is responsible for up to two thirds of the total cavity loss. Studies will be presented demonstrating the precision of surface conductivity determination via Q-measurement and the impact of uncertainties in test body position and geometry.

Significant progress towards the suitability of Additive Manufacturing (AM) metal parts for the production of linear accelerator components has been made in recent years. One significant factor for the suitability of AM parts to produce linac rf structures is the surface quality of the parts. Due to the inherently higher surface roughness of AM metal parts, post-processing is necessary to reach surfaces suitable for rf operation. We present most recent results of surface post-processing trials with AM parts from stainless steel.

The Frankfurt Neutron Source FRANZ will be a compact accelerator driven neutron source utilizing the 7Li(p,n)7Be reaction with a 2 MeV proton beam. Follwoing successful beam commissioning of the 700 keV proton RFQ, further beam experiments including emittance measurements are currently ongoning. Preparations for conditioning and commissioning of the IH-DTL are running in parallel to the current beam measurement campaign. We report on the current status of commissioning towards a 2 MeV proton beam.

The production of low energy high intensity heavy ion beams is challenging for the community. Several high intensity heavy ion beam accelerators for versatile purposes have been developed at IMP, such as LEAF, which is a low energy high intensity heavy ion accelerator complex for multidiscipline researches that features a superconducting ECR source, and a heavy ion beam linac. The major acceleration structure of LEAF is a 4-vane RFQ, which accelerates heavy ions with M/q from 2 to 7 to 0.5 MeV/u. With the support of the energy modulation system based on a DTL and two bunchers, this facility features high intensity heavy ion beam acceleration up to 1 emA, fine tuning of ion beam energy within 0.3 to 1.0 MeV/u with an energy spread of <0.25% (FWHM) that is favored by high precision experimental investigations such as C-C burning study in nuclear astrophysics. A 4-rod RFQ, which was fabricated 15 years ago, has been recently modified and adopted a laser ion beam source as primary ion beam injector to accelerate high intensity pulsed heavy ion beams, especially for refractory metal ions. In addition, a very compact IH RFQ with frequency of 81.25 MHz has been developed to accelerate H2+ ions with currents of several mA. The cavity outer diameter is only 266 mm, which makes it possible that the RFQ could be embedded into a cyclotron and acts as the axial injector of high intensity ion beams. This report will present the latest progress and challenges of the aforementioned work.

The SNS Drift Tube Linac (DTL) operates at 402.5 MHz and consists of 6 RF tanks, DTL1 to DTL6, which can accelerate the H- beam from 2.5 MeV to 87 MeV before entering the Coupled Cavity Linac (CCL). Each DTL tank assembly has 2 sets of horizontal and vertical electromagnetic steering magnets (24 in total) required for transverse beam steering. The coils of these steering magnets were routed to specific shapes with water-cooled copper tubing to fit the limited space inside the drift tube bodies. After operating over 20 years, some steering coils start having water leaks. Spare drift tubes including the steering ones are under development at SNS. To simplify the steering coil routing and avoid water leaking issues, a non-water-cooled steering magnet design has been developed for the replacement of existing magnets. With the existing yoke, the new coils are designed to produce the same magnetic field with a low electric power. According to the CST simulations, the maximum temperature of the coils is below 50 C with no water cooling. A prototype development is in progress and will be used for thermal test and magnetic field verification. Details of the steering magnet design and calculation results are presented in this paper.

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 linac components. In this case, the internal drift tube structure has been produced from 1.4404 stainless steel, as well as pure copper using AM. We present the most recent results from high power tests with the AM IH-type structure.