Electrostatic deflector development at the Chalk River superconducting cyclotron

The development of an electrostatic deflector used to extract heavy-ion beams from the Chalk River superconducting cyclotron is described. Improvements incorporated into the deflector have allowed extraction of ion beams of up to 50 MeV/amu, the design goal of the accelerator. Voltages over 90 kV have been reliably maintained over a 7.5 mm gap with a magnetic field of 3 T. Voltages of 74 kV have been used with a reduced gap of 4.75 mm to extract beams with magnetic fields up to 4.25 T. Major progress was achieved when a water-cooled, negative high-voltage electrode was introduced, and the sparking plates and the thin septum were changed from molybdenum to stainless steel. Efforts are continuing to attain a field of at least 143 kV/cm over a gap of at least 6 mm width.<>