METHOD OF REDUCING AXIAL BEAM FOCUSING

摘要

A method is disclosed for minimising the diameter of the magnet poles of a cyclotron system for production of radioactive tracers. The method selects an operation mode having nu z defined below the critical resonance value of nu z=1/2 and chooses a valley technique having shallow valleys by selecting a first magnet pole parameter defining a valley gap accepting a narrow spaced RF electrode system and size facilitating a vacuum conductance necessary for obtaining a low enough pressure. The method then defines a second magnet pole parameter by setting a sector gap size. The magnetic azimuthal field shape is transformed from being "square-wave"-shaped to becoming approximately sinusoidal by increasing the magnetising field. Then an average magnetic field is calculated from the increased magnetising field and the first and second magnet pole parameter. A pole diameter can then be established to obtain a most compact design of the electromagnet for a cyclotron system. A cyclotron system in accordance with the method is also disclosed.