Results of magnet prototype evaluation for the fermilab energy doubler project

The Fermilab Energy Doubler project will require some 744 dipoles 6 meters long and 240 quadrupoles of varying lengths from 1.5 meters to 2 meters. Since earliest conception the Energy Doubler has been envisaged as an adjunct accelerator located in the same tunnel as the present Main Ring and capable of reaching a final proton energy of ∼1000 GeV. To do this using a lattice similar to the Main Ring's requires a bending field of 45 kilogauss and, consequently, superconducting magnets.[1] The magnet fabrication and testing program was initiated in September 1972, operated the first test magnets in January 1973, settled on a shell type geometry by June 1973, tested and evaluated a matched set of dipoles by November 1973 and operated the first 6 meter, or "20 ft", prototype dipole by March 1974. The 20 ft dipole did not perform satisfactorily, reaching less than 50% of design current and exhibiting excessive training. Consequently, a redirection of the program channeled further efforts into a 2.5 ft model program to identify and correct the sources of difficulty and to enable resumption of 20 ft prototype construction. The first phase of the 2.5 ft program has included the construction and testing of 12 magnets and is essentially complete. It has led to the promise of an improved wire and a slightly more conservative magnet design that is now being used in the construction of 2 1/2 and 10 ft models. Events in an intensive development program do not proceed in logical sequence. While the 2.5 ft model program has been in active progress, two additional 20 ft prototype dipoles of the original design and one 7 ft quadrupole have been completed. One of these, 20 ft dipole #2, has been successfully operated in the forced flow liquid helium pump loop.[2] A 7 ft warm iron quadrupole has also been tested successfully and would be adequate in present form for use in the Doubler project.