Extraction Efficiency Improvement through Central Region Studies

To enhance Crocker Nuclear Laboratory´s ability to supply large beam currents to experiments in MFE, medical, and basic nuclear physics, it is necessary to increase the extraction efficiency of its cyclotron. Adding axial slits to the central region (as done at SIN) has increased deuteron extraction efficiency from 55% to 75%. Another improvement planned will decrease the large radial phase space presented to the extractor. A radial slit system is being designed to limit the radial momentum and displacement from early equilibrium orbits. To optimize this, studies were made with a 3-dimensional electrolytic tank system in which realistic central electric fields can be simulated. Central orbits were calculated using an adaptation of the Michigan State University code PINWHEEL, which allows placement of radial slits. Using a general orbit code the ions are then accelerated to the extractor where radial phase space and extraction efficiency are determined.