VARIABLE ENERGY EXTRACTION FROM THE UCLA 50 MEV CYCLOTRON.
CALIFORNIA UNIV LOS ANGELES
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A scheme for the extraction of a 25 to 47 MeV proton beam into a common external beam-transport system was studied for use with the UCLA 50 MeV cyclotron. The extraction is accomplished by stripping negative hydrogen ions with a thin foil. The magnetic field is held constant while the radius and azimuth of the stripping foil are chosen so that the trajectories for any energy cross at a common point outside the cyclotron vacuum tank. A small combination magnet placed at this crossover point bends the trajectories into a common beam-transport system. The feasibility of this scheme was studied by computing the ion-optic matrix for the cyclotron fringing field for 25, 30, 35, 40 and 45 MeV. The beamspot size calculated indicates a one hundred per cent extraction efficiency in this energy range. Author