• T.J. Zhang, Y.L. Lu, C. Wang, S.M. Wei, J.J. Yang, H.J. Yao, J.Q. Zhong
  CIAE, Beijing

CYCIAE-100 is a 100 MeV, 200 muA H^- cyclotron being constructed at CIAE. The tolerance of the magnetic field is as tight as 1.2 Gauss for isochronous field and 2 Gauss for first harmonics. Due to the absence of coil adjusting in this machine, a measure that helps to achieve a more compact structure (435 ton for the main magnet), the imperfection hence becomes a much more critical factor in our consideration. The effects by the various kinds of imperfection are investigated numerically and the imperfection fields are predicted for beam dynamics simulation, serving as a basic guidance in the magnet construction for CYCIAE-100. Some of the important results will be reported in this paper, including

1. the deformation of the main magnet by the gravity itself, 480 ton EM force and 120 ton vacuum pressure,
2. segregation, inclusion and contraction cavity induced by the casting procedure,
3. fabrication and assembling tolerance, and
4. thermal deformation.

• T.J. Zhang, C.J. Chu, G.F. Song, S.M. Wei, J.Q. Zhong
  CIAE, Beijing
• J.J. Yang
  TUB, Beijing

To limit the cost for the main magnet of a compact cyclotron CYCIAE-100, the cast steel is used for the top/bottom yoke and return yoke. The imperfection may not be ignored and the harmonic coils on the return yokes will make the fields reaching the requirements easier during the shimming. The centering coils will not only compensate the 1st harmonic fields at the center region, which is usually remain big, but also correct the off-center injection of the beam. The thermal deformation and the vacuum pressure may change the fields distribution during the machine operation and therefore It is necessary to use trim coils to adjust the fields. We arrange the trim coils inside the two opposite valleys of the main magnet. The second harmonics from the trim coils are not big eough to affect the beam dynamics significantly from the beam dynamics study. In this paper, the effects of correction coils of three types are presented. The detail configuration of the correction coils is introduced in the paper as well. One concern is the potential interference of some water cooled coils could have with vacuum. Some experience for the coils inside the high vacuum tank is tested and the results are given.

• T.J. Zhang, Y.J. Bi, F.P. Guan, X.L. Jia, S.M. Wei, J.Q. Zhong
  CIAE, Beijing
• G. Dutto, G.H. Mackenzie, L.W. Root
  TRIUMF, Vancouver
• J.Z. Wang
  Department of Physics, Central China Normal University, Wuhan

There is increasing interest in high current compact H^- cyclotrons for RIB, isotope production or as injectors for sub-critical reactor testing facilities. For compact cyclotrons, a practical limit on the output energy, to prevent significant Lorentz stripping and resulting activation, is ~100 MeV. Vacuum dissociation is another critical problem, because a compact structure and small parts inside the tank make high vacuum challenging. This paper describes how Lorentz stripping and vacuum dissociation were calculated for our “CYCIAE-100” under construction. In order to take into account non uniform magnetic fields and vacuum, losses were calculated by numerically integrating loss equations along tracked orbits, as these were being calculated by the beam dynamics code. To verify the code, losses derived with field and vacuum data from the TRIUMF 500 MeV cyclotron were compared with measurements. For the CYCIAE-100 cyclotron we predict that electromagnetic losses will account for less then 0.3% of total beam, vacuum losses for less than 0.58%, with peak magnetic fields up to 1.35T and average vacuum up to 5·10^-8 Torr.