Eric Forton

Magnet Developments and Commissioning for the IBA Compact Gantry

The ProteusOne gantry will be the first IBA gantry with scanning upstream of the last bending magnet. This configuration offers the combined advantage of compactness and Pencil Beam Scanning (PBS) with reasonable source to gantry axis distance (SAD). This new proton therapy gantry required modifications on existing IBA beam line magnets as well as development of new ones. This paper presents the basic features and advantages of the gantry optics and details the magnets that needed to be designed. In addition, some specific issues raised by the gantry compactness will be detailed. The scanning magnet and the last, wide gap, bending magnet required special attention to ensure good quality beam optics. Indeed, due to the small distance between them, careful design is required to minimize their mutual influence. Parts of the gantry structural elements also had to be taken into account, adding complexity to the magnetic modeling and requiring very good collaboration between beam optics and mechanical design teams. Finally, some details of the commissioning of the magnets and model crosschecks are also presented.

Cold head maintenance with minimal service interruption

Turn-key superconducting magnet systems are increasingly conduction-cooled by cryogenerators. Gifford-McMahon systems are reliable and cost effective, but require annual maintenance. A usual method of servicing is replacing the cold head of the cryocooler. It requires a complicated design with a vacuum chamber separate from the main vacuum of the cryostat, as well as detachable thermal contacts, which add to the thermal resistance of the cooling heat path and reduce the reliability of the system. We present a rapid warm-up scheme to bring the cold head body, which remains rigidly affixed to the cold mass, to room temperature, while the cold mass remains at cryogenic temperature. Electric heaters thermally attached to the cold head stations are used to warm them up, which permits conventional cold head maintenance with no danger of contaminating the inside of the cold head body. This scheme increases the efficiency of the cooling system, facilitates annual maintenance of the cold head and returning the magnet to operation in a short time.

Development of Cyclotrons for Proton and Particle Therapy

All particle therapy systems are modular systems built with smaller subsystems. The various modules are (1) the beam production system, (2) the beam transport system, and (3) the beam delivery system as shown in Fig. 2.1.

Constant Field Toroidal SMES Magnet

The Massachusetts Institute of Technology has been performing a preliminary study of superconducting magnetic energy storage (SMES) magnet configurations under a Pôle MecaTech Cluster collaboration sponsored by the government of the Walloon Region in Belgium. Consortium members include Ion Beam Applications S.A. (IBA), CE+T Power (CE+T), Euro-Diesel S.A. (Euro-Diesel), Jema S.A. (JEMA), the University of Liege (ULG), the Catholic University of Louvain-la-Neuve (UCL), and the Liege Space Center (CSL). The goal of the project was to assess the commercial feasibility of various SMES magnet configurations by evaluating specific energy, magnetic field shielding properties, and manufacturing cost. Among the examined configurations, the constant field toroid (CFT) attracted our attention, and it is the subject of this paper. The present study presents the description of the magnetic design algorithm and an example of the first-level optimization of the stored and specific energy. Numerical simulations are performed using Cobham Opera. A procedure of a simplified analytical optimization of a magnet system is used to maximize the stored energy or the specific energy (per unit weight of the conductor) of a CFT magnet.