Zero Gradient Synchrotron Ring Vacuum System

The Zero Gradient Synchrotron is a weak focusing machine. This makes possible multiturn injection which results in a high intensity beam. Ideally, all of the space between the magnet pole faces and the magnet coil would be utilized for beam at injection. This need requires the vacuum chamber for the machine to have a large vertical aperture across a broad radial width. The chamber of the ring magnet vacuum system is a closed ringabout 560 ft in circumference (Fig. 1). Approximately three-fourths of this chamber length is within the eight magnet sections where the minimum cross-section exists (32 in. wide by 5-1/4in. high). The closed magnet design restricts the pumps to positions on the straight section boxes between magnets, thus spacing these pumping stations approximately 70ft apart. Space limitations, eddy currentproblems, and heat problems determined the design approach to the vacuum chamber within each of the eight ring magnets. The resulting design necessitates the need for both an inner and outer chamber, since the inner (high vacuum chamber) design cannot withstand a pressure differential of one atmosphere.