The Pretoria cyclotron facility

After suspecting misaligned pole plates as the underlying cause of the vertical dispersion and displacement of the extracted beam, it was decided to undertake a major service of the cyclotron during the first quarter of 1986. The main vacuum chamber was removed, the O-rings replaced and the magnetic field measured. Other improvements included the installation of a new electromechanical drive system for the capacitor plates, modifications to the vacuum valve of the isotope production chamber, the installation of a new chiller for the deflector and the upgrading of the main magnet stabilizer with a new shunt. During this period two programmable controllers were commissioned to interlock the water flow circuitry with the existing interlock subsystems, a new power supply was installed for the ion source filament and new vacuum sensors located on the therapy beamline. The frequent interruptions and breakdowns during the past year have highligted once more the need for support from the Faure personnel and two major improvements are to be jointly undertaken; a theoretical study of particle orbits at the central region of the cyclotron with the aim of improving orbital separation and the design of an electromechanical drive system for the ion source. 1 tab