Design studies on superconducting Cos &thetas; magnets for a fast pulsed synchrotron

The new heavy ion synchrotron proposed by GSI will comprise two superconducting magnet rings in the same tunnel, having rigidities of 200 T.m and 100 T.m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss and field distortion. This paper discusses the 200 T.m ring, which will use Cos θ magnets based on the RHIC dipole design. We describe options for the low loss Rutherford cable that will be used, together with a novel insulation scheme designed to promote efficient cooling. Measurements of contact resistance in the cable are presented and the results of these measurements are used to predict the ac losses, temperature rise and field distortion in the magnets during fast ramp operation.