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
- the deformation of the main magnet by the gravity itself, 480 ton EM force and 120 ton vacuum pressure,
- segregation, inclusion and contraction cavity induced by the casting procedure,
- fabrication and assembling tolerance, and
- thermal deformation.
CIAE, Beijing
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.
TUB, Beijing
PSI, Villigen
CIAE, Beijing
In high intensity cyclotrons with small turn separation, both the space charge effects of single bunch and the interaction of radially neighbouring bunches play important roles. A PIC-based three-dimensional parallel code, OPAL-CYCL, is newly developed under OPAL framework which self-consistently covers these two collective effects. In this paper we also present the simulation results from the compact cyclotron CYCIAE-100 in the context of the ongoing upgrade program of BRIF at CIAE, with the goal of 100 MeV, 200 μA CW proton beam on target.
CIAE, Beijing
Department of Physics, Central China Normal University, Wuhan
Light II-A pulsed power generator was used as a power driver of pumping KrF laser at CIAE. The redesign of Light II-A pulsed power generator is based on the consideration that the machine will consist of one single Marx generator with two different experimental lines，which is presented in this paper. The original experimental line with characteristic impedance of 5Ω is remained, and a new line of low impedance (about 1.5Ω ) is added to the Marx generator. The structure design and the electric insulation design are introduced. It is also outlined here the manipulation of modeling the dynamic behavior of gas discharge arc as well as the circuit simulation results of the two experimental lines. Meanwhile a brief introduction is given to the potential application of the low impedance line.
CIAE, Beijing
TRIUMF, Vancouver
As a high intensity compact cyclotron, CYCIAE-100 is designed to provide proton beams in two directions simultaneously. At the extraction region, the fringe field of the main and the field of the combination magnet will influence the beam optics. The fringe field may become critical by comparison with the separated sector machine because of the compact structure. The dispersion during the beam extraction should not be ignored, which may make the beam envelop become evidently bigger. Then the beam loss and residual radiation increase. To study the beam optics at the extraction region of CYCIAE-100, the orbit tracking and transfer matrix calculation and symplectic by function extension of the code GOBLIN and modification of STRIPUBC have been implemented. The characteristics of the extracted beam have been investigated based on the main field from a FEM code and overlapping with the field generated from the combination magnet at each extraction port. The results are also compared with those from the CIAE’s code CYCTRS to confirm this precise prediction. The transfer matrix from this simulation is analyzed and used for the down stream beam line design.
CIAE, Beijing
FZJ, Jülich
The 10 mA, 40keV H- pulsed injection line for the CIAE 10 MeV CRM cyclotron has two main operation modes for bunched beams: delivering 5 mA CW beam or chopped pulse with more than 100uA. Chopped pulse is achieved by placing behind the 70.5 MHz bunching cavity a sinusoidal transverse deflecting cavity with frequency of 2.2 MHz, 1/32 of the bunching frequency. Particles outside the wanted ±3° phase width @ 2.2 MHz, corresponding to ±90° @ 70.5 MHz, are either absorbed in a 50cm drift after chopper or at round slit1, 1cm aperture. Time dependence of sinusoidal chopping field causes RMS emittance increase by a factor 3 and changes twiss parameter alpha by a factor 2 before the round slit1. Solenoid couples motion in transversal planes, but equalizes both RMS emittances. Particle tracking results are presented for the chopped pulse, showing longitudinal-transverse coupling in the deflector and equalization of RMS emittances in the solenoid. Optimised focusing strength leads to about 1 % transmission efficiency for the chopped pulse. The CRM inflector receives 2.4 ns long pulse at about 4.4 MHz repetition rate, 1/16 of the RF frequency.
CIAE, Beijing
TRIUMF, Vancouver
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.