Search

The Superconducting Ion Gantry (SIG) project aims to design, construct, and test a curved superconducting dipole demonstrator magnet for an ion gantry (up to a rigidity of 6.6 Tm). The main demonstrator magnet parameters are a dipolar field of 4 T generated into a toroidal aperture with an 80 mm diameter, 1.65 m curvature radius, and 30° angular sector. The project is inserted in the framework of the EuroSIG collaboration among CNAO, CERN, INFN, and MedAustron. Within this collaboration, the main goal of SIG is to perform a feasibility study of winding and assembling cos-$\theta$ coils with a small curvature radius. In addition, a parallel program at CERN is dedicated to the study of the indirect cooling problem through the construction of a straight thermal demonstrator magnet sharing the SIG cross-section. The basic idea behind these programs is to check whether the vast experience of the community on superconducting accelerator magnets design can lead to a breakthrough in the gantry magnets domain. This article shows the main elements of the conceptual design of the SIG magnet and reports on the first winding trial performed at the LASA laboratory, in Milan, with a copper dummy cable. Moreover, possible solutions for the winding, curing, and impregnation of highly curved cos$\theta$ coils are discussed.

The use of Canted Cosine Theta (CCT) magnets for accelerator applications has gained popularity due to their ease of manufacturing and assembly. In the context of two EU-Horizon2020-funded projects, HITRIplus and IFAST, the development of two 80 mm free bore and 4 T central field CCT dipoles for use in ion therapy (hadron therapy) is underway. In IFAST, a straight dipole CCT features a superimposed quadrupole component (combined function winding), while in HITRIplus a curved CCT (bending radius of 1.65 m) is wound as pure dipole. Both projects are based on a Cu/Nb-Ti multistrand rope as conductor. The article presents advancements in the engineering design of the magnets. A number of validation tests have been made to validate the choices made during the conceptual design. Characterization tests of the low losses rope, winding tests, splice tests, and impregnation tests will be described. The explored alternatives for the fabrication of the curved formers and the support structure are also discussed.

As part of major European collaborations focused on the study of newly developed superconducting magnets for ion therapy, Istituto Nazionale di Fisica Nucleare (INFN) is directly involved through the Superconducting Ion Gantry (SIG) project. In ion therapy, rotating gantry systems are critical to better preserve healthy tissues during treatments, but they are typically huge and heavy structures: a superconducting version of them would lead to lighter and more viable solutions. SIG aims to design, in collaboration with Centro Nazionale di Adroterapia Oncologica (CNAO) and Conseil Européen pour la recherché Nucléaire (CERN), the main superconducting magnets for a 430 MeV/u carbon ion gantry. The main purpose of the project is to study the bending dipoles of this system: they are expected to have a curvature of 1.65 m, aperture of 80 mm, magnetic field of 4 T, ramp rates up to 0.4 T/s and Nb-Ti coils. Among the goal of SIG is the construction of a 30-degree demonstrator to prove the feasibility of these magnets. The plan is to design cos $\theta$ magnets, but we are currently working on an alternative strategy with cross section in block coil configuration. These parameters are very challenging and this solution could make it easier to achieve the required goals. In this work the optimized cross section and a novel winding technique for high curvature block coil magnets are presented.

The European project IFAST's WP8 Innovative Superconducting Magnets aims to develop the technology of Canted Cosine Theta (CCT) magnets wound with High-Temperature Superconductors (HTS). Superconducting magnets could lower the size and cost of synchrotrons and gantries for research and hadron therapy. HTS materials can lead to higher magnetic fields with smaller cryogenic systems than LTS. However, they pose challenges in cable production schemes, magnet design, and cost. The project's final goal is to design a straight CCT-layout magnet with a central dipole field of 4 T, and a ramp rate of 0.4 T/s, but a lower ramp rate of 0.15–0.2 T/s is acceptable for the first step. The paper presents a preliminary design, discussing in particular the protection scheme with the magnet protection solutions for the conductor: one with two and the other with four HTS tapes. Both options generate 4 T of dipole field without an Iron shell, with at least 10 K of margin at an operational temperature of 20 K. To meet the time and budget constraints of the project, a simple cable based on a co-winding of commercial REBCO tapes is proposed. Protection is the most challenging aspect of the design and an adiabatic quench analysis has been used to determine the required thickness of copper stabilizer tapes to mitigate the risk of damaging the magnet during a quench. Finally, the paper evaluates ac and radial current losses during the magnet cycles, discussing the heat distribution and possible solutions for heat extraction.

The quest for advancing science and technology continues with the Future Circular Collider (FCC), which requires 16 T bending dipoles to be installed along its 100 km tunnel to achieve a center-of-mass energy of 100 TeV, in its hadron-hadron version. The promising Nb$_{3}$Sn technology for superconducting magnets presents a potential solution for large-scale production. In line with this, the European strategy for particle physics has urged for increased efforts in High Field Magnet R&D, specifically in constructing demonstrators for Nb$_{3}$Sn technology. To address this call, the Istituto Nazionale di Fisica Nucleare (INFN) and CERN entered into an agreement to build a 1.5 m long cos-theta dipole in Nb$_{3}$Sn, called Falcon Dipole (The Future Accelerator post-LHC Cos-theta Optimized Nb$_{3}$Sn Dipole). The project aims to consolidate the fabrication process for Nb$_{3}$Sn superconducting dipoles in the 12–14 T range, engaging industry partners in the initial stages of the R&D phase. This article provides a recall of the magnet design features and highlights the progress made in the development activities. Critical processes like the reaction treatment and the impregnation are discussed, with an emphasis on the test outcomes and the challenges faced. By taking these into account, plans for the production of the coils for the final configuration can be effectively formulated.

As part of the research project called FCC-hh led by CERN, which aims to study the possibility of building a new 100 TeV center of mass energy particle collider along an 80-100 km circumference tunnel, there are many collaborations underway to test different designs for the main bending dipole of the collider. One of these collaborations involves INFN, the Italian Institute of Nuclear Physics, which has been working on the cos $\theta$ design until 2019 as part of the European EuroCirCol project. This study consisted of a conceptual design of a 16 T, double-aperture, four-layer dipole made of Nb$_{3}$ Sn. Considering the challenge that such a cutting-edge magnet represents, this conceptual design resulted in a 5-year agreement between INFN and CERN in order to study and build a 1.5 m long, single aperture, cos $\theta$, Nb$_{3}$ Sn dipole with a target magnetic field of 12 T. This project is called the Future Accelerator post-LHC Cos $\theta$ Optimized Nb$_{3}$ Sn Dipole (or FalconD for short). In this paper we present the mechanical analysis of this project after some major cross-sectional upgrades that have impacted the design by easing the assembly phase. One of the most challenging aspects of this design is its mechanical structure that must handle the intense magnetic forces generated by such a high magnetic field. The mechanical structure is based on the “bladder & key” (B&K) concept and it has never been adopted before in a cos$\theta$ dipole, so it needs to be validated. This contribution presents the 2D FEM of the FalconD, showing the mechanical behavior of the magnet during each construction step.

Canted Cosine Theta layout for accelerator magnets is a very attractive since such magnets can be manufactured and assembled without big tooling, and with a relatively modest number of parts and tools. In the frame of European Horizon2020 funds, two collaborations, HITRIplus and I.FAST, are developing a CCT design, of 80 mm free bore, 4 T central dipole field, and 0.4 T/s ramp-rate. This magnet is expected to be the bending element of a gantry, to control the beam delivery in therapy with ions (hadrontherapy). The paper illustrates first a comparison between CCT and more classical cosine theta layout, followed by the comparison between Nb-Ti, Nb3Sn, MgB2, and HTS tapes coils. Relevant requirement for the magnets of this study is to be operated at low current, to limit the heat generation, in sight of a liquid-free cooling system. The results of the comparison is then applied to the design of two magnet demonstrators. Both adopt a low-losses Nb-Ti rope, consistently with the need for keeping the heat generation as low as possible. The first is a straight combined function dipole-quadrupole, while the second is a curved CCT dipole. The paper concludes with the first manufacturing tests for the CCT formers, for which aluminium -bronze, stainless steel and charged PEEK polymer are being explored as basic material.