Status of the Magnetic Design of the SSC Dipole Magnets

Abstract

The purpose of this paper is to discuss. The status of the magnetic design of the SSC collider dipole magnets (CDM’s). The majority of the work performed to date is the optimization of the coil cross-section, with most of the emphasis on the b2, b4, and a1 multipoles. The basic approach to cross-section optimization involves the following steps. First, a detailed 180 degree finite-element model is constructed. This model also includes material magnetic property data for the Nitronic-40 collars, Fe yoke, steel cryostat, and beam tube. The resulting transfer functions for all the normal multipole components b2–b10 as well as the skew quadrupole a1 (due to the asymmetric cryostat) are calculated for the nominal conductor cross-section. Persistent current effects are incorporated into the model using recent 50mm, 1.8m long coil data. The initial cross-section is then modified to include off-sets in the b2 and b4 multipoles due to the permeable collar, cryostat, beam tube, persistent currents, and deflections due to cool-down and Lorentz loads. The resulting cross-section represents our best estimate of what the dimensions of the warm, collared and yoked coil are. The off-sets due to the various deflections are a result of a finite-element stress analysis; any uncertainties in these calculations will impact the deflection off-sets put into the magnetic cross-section. However, the calculated off-sets are still an indication of the trend of the various effects, and are expected to provide greater understanding of the measured systematic multipoles.