Mechanical features of the electrostatic deflector for the Berkeley 88-inch cyclotron

Abstract

The mechanical features of the electrostatic deflector are described. The deflector channel starts as close as possible to the dee. It must deflect the particles enough to clear the leg of the magnet. The channel width at entrance is 5/32 in. (0.4 cm) and at exit is 1/2 in. (1.3 cm). The nominal voltage is 63 kV. The deflector is 108 deg long. It is built of four segments, two in the outer high-voltage element and two in the inner ground element. The channel elements are water-cooled welded Inconel. Each of the two high-voltage elements is separately cantilevered from an insulating bushing. The whole assembly is built like a drawer. The floor of the drawer is a 1/2-in. sheet of K-Monel. Bearings throughout are Teflon-impregnated sintered bronze. A moving 1/4-scale model of the deflector elements is installed in the control room. It reproduces automatically all motions of the deflector in the cyclotron. The initial deflector is equipped with a standard metal fixed septum. A sawmill septum is being developed to replace the standard septum when and if desired. This sawmill septum consists of two metal rotating disks.