Mechanical Design of a Regenerative Deflector for the Berkeley 88-Inch Cyclotron

Abstract

Following the success of a test electrostatic regenerator unit in the Berkeley 88-in. cyclotron, a new regenerative deflection system was built. The system was comprised of a regenerator unit and an electrostatic channel. The regenerator unit was positioned opposite the dee near extraction radius. This unit having a positive voltage gives the last few accelerating internal beam orbits such a bump off their normal orbit paths that their turn-to-turn separation was increased at the entrance to the deflector channel. This separation decreased the amount of beam dumped on the septum and thus increased the efficiency of the deflector. The electrostatic channel consisted of three pairs of electrodes. Each end of each electrode was positioned remotely from the control room where its radial position was also read. This was made possible by the use of a flexible linear ball-bearing unit connected between the electrode end and a motor drive unit located outside the cyclotron vacuum barrier. This same motor unit also drove a system of selsyns for position readout. The entrance septum elevation was also remotely adjustable. The septum was mounted on a linear ball-bearing wedge driven by a unit similar to that used in positioning the electrodes. The regenerative deflector was installed in November 1965 and delivered beam when first tried. It is presently undergoing beam development alternately with delivery of experimental beam.