Estimation of acceptance of the beam extraction system of K500 superconducting cyclotron

The extraction system of the KSOO superconducting cyclotron consists of two electrostatic deflectors and eight passive magnetic channels, spanning over an azimuthal length of 330 degrees, with radial aperture of ∼6 mm. The radial position of the elements can be varied within ±6 mm. The extraction path is within the fringing field of the cyclotron. So, different positions of the magnetic elements change the optical properties of the extraction system, as seen by the beam. Here we have approximated the entire extraction path by a series of equivalent combined function magnetic elements, having variable field and gradient for different ion species and energies. The acceptance of the extraction system at the entry of first deflector has been determined. The accelerated beam can be extracted only if its emittance matches with this acceptance aperture. The acceptance calculation also predicts the tolerance limit of the magnetic field imperfections in the acceleration zone. (author)