Beam quality study in RCNP six-sector ring cyclotron

Proposed ring cyclotron consists of six-sector magnets, three accelerating cavities and a flat-topping cavity. Assuming various voltage distributions in these cavities, beam behaviors have been calculated. An unbalance of acceleration voltages generates the motion of the orbit center. The radial betatron amplitude grows by a perturbation relating to energy gain at cavities and a radial periodic field distribution, which is produced by the field correction using trim coils. This effect can be canceled completely by a rearrangement of cavity voltage and a first harmonic field component. Theoretical results on perturbations by the radial periodic field predict the existence of a radial betatron resonance for cyclotrons with different numbers of sectors and cavities. (author)