Speaker
Description
When this author started his career as an accelerator engineer over 60 years ago, accelerator dipoles were combined function iron dominated magnets that produced a dipole field overlaid with a quadrupole field. These were the same type of magnets that were in the Brookhaven AGS and the CERN PS machines. These magnets produced an induction of ~1.5 T at the beam center. The largest detector magnet of that period was the 1.93 m (72 inch) 1.8 T bubble chamber at Berkeley. In 1961, an 8.8 T small Nb3Sn solenoid showed that high fields could be produced using superconductors. Accelerator physicists dreamed of dipole and quadrupole magnet that could produce peak fields of >4 T, which would allow higher energy machines to be built on less land. These machines would have dipoles, focusing and defocusing quadrupoles, and correction magnets that could be superconducting. The earliest superconducting accelerator magnet this author knows about is a Nb3Sn tape quadrupole built by W. B. Sampson at Brookhaven National Laboratory (BNL) in 1965. The six-week 1968 summer study at BNL had an objective of studying superconducting accelerator magnets, RF cavities and large detector magnets for bubble chambers. This paper discusses the concepts behind the codes that calculated the magnetic fields where the accelerated beam is located. The programs that this author and others used to design accelerator magnets and detector magnets will be described. These programs calculated both the transport current field and the fields due to circulating currents in the superconductor. These programs could also assess the effects of small errors in coil fabrication and support on an accelerator beam. For detector magnet, they had to be fabricated with the desired field uniformity and have a lot of magnetic field where the detector was located. The magnet design was dictated by the requirements of the detector.
