The internal ion source of the Advanced Molecular Image Technologies (AMIT) superconducting cyclotron uses cathodes made of pure tantalum to generate high energy H− ion beams for the production of isotopes for positron emission tomography. During service, the cathodes are impacted by high-energy ions from the plasma. The resulting erosion creates craters that reduce the current density of the extracted beam. The cathodes eventually need to be replaced when the ion source can no longer be activated. This research explores the possibility of repairing the tantalum cathodes used in the AMIT cyclotron through laser metal deposition additive manufacturing. The damaged parts were first characterised by 3D imaging, scanning electron microscopy, and Vickers microhardness to understand the damage mechanisms occurring during service and quantify the extent of the damage. Different repair strategies were then tested employing both high-purity tantalum wire and powder feedstocks and the properties of the reconditioned electrodes were determined. The ability of laser metal deposition to restore the damaged cathodes for use in the AMIT cyclotron has been demonstrated.
The ion source is one of the most relevant elements in a cyclotron , since it determines the injection into the accelerator. An internal cold-cathode Penning ion source has been chosen for the AMIT compact cyclotron. This kind of source is extensively used in cyclotrons to produce negative hydrogen ions . The compactness of the accelerator constrain the beam diagnostic in the cyclotron, motivating the development of an external experimental facility for the commissioning of the ion source. In this paper, the validation of the ion source design and the characterization of the H − beam production are presented. Different chimney geometries modifying the distance between the plasma column and the extraction wall have been tested to obtain the best relation between ion production and plasma conditions. In addition, experimental measurements of the beam profile have been carried out. Current experimental results provide relevant information for the operation in the final cyclotron assembly and the final beam current optimization.
Wave energy conversion is a promising alternative to produce clean energy from the huge available resource at sea, but it is also a challenging mission because extraction conditions are difficult due to the harsh environment and also to the low frequency of the energy conversion process. In this regard, powerful Power Take-Offs are required, able to produce high forces at low frequencies, which also must be highly controllable to optimize the conversion process. This paper presents a new type of Linear Electric Generator based on a novel Switched Reluctance Machine, which is being developed in the framework of a H2020 Project called Sea Titan. The paper describes the calculation and the design processes of a 70 kN prototype which will also be manufactured and tested in the framework of Sea Titan, which also includes a feasibility study for a superconducting solution.
A superconducting magnet able to provide the required field of 4 T has been developed for a compact cyclotron to produce radioisotopes for medical imaging, in the framework of the AMIT project. It consists of two coils in Helmholtz configuration, embedded in a stainless steel casing to hold the Lorentz forces. The cooling scheme is based on a low pressure forced internal flow of two-phase liquid-vapour helium through a narrow channel machined in that casing. This paper reports on the cooling tests and the preliminary magnetic measurements of the magnet. Regarding cooling tests, liquidHelium froma Dewar has been used first to train the magnet and to estimate the thermal losses. Later, refrigeration will be accomplished from a stand-alone cryogenic supply system that would allow a user-friendly operation of the cyclotron, without external supply of cryogens. Regarding magnetic measurements, a custom magnetic measurement bench developed in collaboration with ALBA/CELLS, has been used to map the magnetic field and first results are presented and discussed in this paper.
The present paper describes the development process of a low critical temperature superconducting magnet to be installed in a compact cyclotron producing single-dose radioisotopes for clinical and preclinical applications. After a brief description of the accelerator, the magnet development process is described, starting from the magnetic, mechanical, quench, and thermal calculations, continuing with the designing process, particularly the support structure of the magnet and the cryogenic supply system, to finish with the fabrication and the first tests than have been performed.
The numerical evaluation of magnetic forces exerted by permanent magnets is usually performed by two methods, the integration of the Maxwell stress tensor or by means of virtual displacements and energy balance. In this paper, we will review previous works on this subject, where controversy exists due to the sign of the magnetic energy stored in the magnet itself. We will check the theoretical work in the matter with numerical results from a number of FEM codes, as Ansys, Opera and Quickfield. Several examples of application will be provided. One of those will be the particular case of a phase shifter under development for the XFEL (European X-Ray Free Electron Laser) project. Its purpose is to adjust the phase between two consecutive undulator segments. The magnetic field is obtained in this device through a Halbach hybrid configuration with Nd-Fe-B permanent magnets and Fe-Co poles.