Numerical investigation for high intensity H^- beam injection to a 100 MeV compact cyclotron

As a part of the Upgrade Project of Beijing Tandem Accelerator Laboratory, a 100 MeV compact cyclotron was designed for the generation of high intensity proton beam. In comparison the H^- beam intensity injected into the cyclotron central region of the 30 MeV medical cyclotron developed at CIAE 8 years ago, those injected into the 100 MeV machine will be 4 times higher. So, the axial injection optics was investigated numerically again by means of taking the space charge effect into account. The simulation started from the old layout based on the ES (Einzell lens and solenoid) system in CIAE’s 30 MeV machine and SQQ system (solenoid and doublet) in TRIUMF’s machine, shows that a ESQQ system should be able to match the injection optics better for higher intensity beam injection. A new layout based on ESQQ injection system will be used for the 100 MeV cyclotron. From three-dimensional field computation, the modularization of magnets (S and QQ) are designed so that the injection line ESQQ could be rearranged flexibly. © 2004 American Institute of Physics.