Conceptual design of superconducting quadrupole arrays for heavy-ion fusion

Extensive studies have been performed to optimize the design of superconducting quadrupole arrays for beam transport in future heavy-ion fusion accelerators. In these arrays 20 or more quadrupole coils are densely packed with their axes aligned in parallel. Field strengths between 3 and 5 tesla at the inner coil diameters have been investigated. The aperture of the individual quadrupoles has been varied between 60 and 240 mm. The coils have a typical length of 1 m, and special effort has been made to minimize the length of the interconnect region between the array and adjacent accelerator components. The relative orientation of quadrupoles in the array is chosen to optimize field sharing between neighboring cells. Field uniformity in the boundary cells is maintained by placing concentric correction coils onto these cells. A conceptual cryostat design, which minimizes heat loads on the cryogenic system, has been analyzed. Since inertial fusion energy has to compete with other long-term energy sources, cost and reliability of these magnets are major issues. The presented design uses a round NbTi mini-cable, which allows for a cost-effective, highly automated manufacturing of the required superconducting coils.