Transverse beam dynamics and coupling effects in the Tritron

Tritron is the name of a separated-orbit cyclotron, which is under construction in Munich. The ions are accelerated by superconducting cavities and strongly focused by the alternating gradients of superconducting channel-magnets. Longitudinal focusing is achieved due to an average field gradient larger than the isochronous one, together with an acceleration at phases below 90deg. The normalized field gradients in each of the two magnet types are constant for the twenty turn between injection and extraction. Therefore the absolute values of the two field indices scale linearly with radius, leading to betatron oscillation numbers increasing from turn to turn. The influence of second and higher order distortions of the magnetic field is investigated, yielding limits necessary to avoid particle loss for a certain phase space acceptance. Finally, a procedure to correct the settings of the individual magnets is discussed, which should serve a proper centering of the beam in the narrow magnet channels. (orig.)