Author: Hojo, S.
Paper Title Page
MOPPC069 Quantitative Simulation of NIRS-930 Cyclotron 292
  • V.L. Smirnov, S.B. Vorozhtsov
    JINR/DLNP, Dubna, Moscow region, Russia
  • A. Goto, S. Hojo, T. Honma, K. Katagiri
    NIRS, Chiba-shi, Japan
  The results of the computer modelling of the structural elements of the NIRS-930 cyclotron operational at the National Institute of Radiological Sciences (Chiba, Japan) are presented. The integrated approach to modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics simulations is described. A computer model of the cyclotron was constructed. Electric and magnetic field distributions and mechanical structures were converted to the beam dynamics code for simulations, in which particle losses on the surfaces of the system elements were estimated. The existing data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron and beam parameter measurements are used for calibration of the simulations. New acceleration regimes could be formulated with the help of the constructed computer model of the machine.  
MOPPD028 Observation of Longitudinal Space Charge Effects in the Injection Beam Line of NIRS-930 Cyclotron 427
  • S. Hojo, A. Goto, T. Honma, K. Katagiri, A. Sugiura
    NIRS, Chiba-shi, Japan
  Dependence of bunching efficiencies on the position of a beam buncher was measured for the AVF cyclotron at the National Institute of Radiological Sciences (NIRS) for 30 MeV proton beams with intensities up to 100 microamperes at injection. The measurement was carried out for two positions: 1.53 m and 2.33 m upstream from the inflector. For the buncher position of 2.33 m the bunching efficiency decreased, as the beam intensity increased, to about half of that at low intensities, while for 1.5 m it was constant up to 100 microamperes. The intensity distributions of extracted beam with respect to the buncher phase were also measured for the two buncher positions. The dependence of bunch width on the beam intensity is discussed by comparing the data with one-dimensional simulations on longitudinal space charge effects.