A. Hodgkinson

Design of an Achromatic Superconducting Magnet for a Proton Therapy Gantry

Recent studies have shown that strong, alternating focusing magnets can be used to greatly increase the momentum acceptance of hadron therapy gantries. With the high gradients achievable with superconducting magnets a level of momentum acceptance can be reached which may have significant implications to medical gantries and to the introduction of superconducting technology in this area. The design of such a superconducting magnet system for a proton therapy gantry will be presented. The Canted-Cosine-Theta concept is extended to a curved magnet system generating the desired bending and alternating focusing fields for the achromatic optics. Magnetic, structural, and thermal analysis of this design is presented along with preliminary efforts towards fabrication and assembly of the curved magnet.

Design of a New Superconducting Magnet System for High Strength Minimum-B Fields for ECRIS

A novel Mixed Axial and Radial field System (MARS) seeks to enhance the B fields inside the plasma chamber within the limits of a given conductor, thereby making it possible to raise the operating fields for Electron Cyclotron Resonance Ion Sources (ECRISs). The MARS concept consists of a hexagonally shaped closed-loop coil and a set of auxiliary solenoids. The application of MARS will be combined with a hexagonal plasma chamber to maximize the use of the radial fields at the chamber inner surfaces. Calculations using Operas TOSCA-3D solver have shown that MARS can potentially generate up to 50% higher fields and use of only about one half of the same superconducting wire, as compared with existing magnet designs in ECRISs. A MARS magnet system built with Nb3Sn coils could generate a high strength minimum-B field of maxima of ≥ 10 T on axis and ~6 T radially in an ECRIS plasma chamber. Following successful development, the MARS magnet system will be the best magnet scheme for the next generation of ECRISs. This paper will present the MARS concept, magnet design, prototyping a copper closed-loop coil, and discussions.

DIANA - A deep underground accelerator for nuclear astrophysics experiments

DIANA (Dakota Ion Accelerator for Nuclear Astrophysics) is a proposed facility designed to be operated deep underground. The DIANA collaboration includes nuclear astrophysics groups from Lawrence Berkeley National Laboratory, Michigan State University, Western Michigan University, Colorado School of Mines, and the University of North Carolina, and is led by the University of Notre Dame. The scientific goals of the facility are measurements of low energy nuclear cross-sections associated with sun and pre-supernova stars in a laboratory setup at energies that are close to those in stars. Because of the low stellar temperatures associated with these environments, and the high Coulomb barrier, the reaction cross-sections are extremely low. Therefore these measurements are hampered by small signal to background ratios. By going underground the background due to cosmic rays can be reduced by several orders of magnitude. We report on the design status of the DIANA facility with focus on the 3 MV electrostatic accelerator.