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The results of numerical modeling of the transmission efficiency of ion beams in conditions of ion recharge on the residual gas in the vacuum chambers of the vacuum system of the DC-60 cyclotron complex are presented. The outcomes of the simulation have provided the determination of the main parameters and technical requirements for all parts of the total vacuum system of the DC-60 cyclotron complex designed for applied researches using an ECR-type ion source and accelerated ions from Carbon to Xenon at the University in Astana in the Republic of Kazakhstan. The vacuum system of the accelerator complex includes the low energy channel with an ECR ion source for the autonomous researches on irradiation by ions and the axial injection line into the cyclotron, the cyclotron vacuum chamber, as well as the transport channels of accelerated and extracted ion beams. The energy of the extracted beams can be varied from 0.9 up to 1.66 MeV/nucl in the case of acceleration on the 4th harmonic mode and from 0.4 up to 0.8 MeV/nucl in the case of the 6th harmonic mode. The computer modeling programs GENAP and VACLOS have been applied for ion transmission efficiency calculations and for the optimization of vacuum parameters. These programs have been developed and tested on the basis of experiments in four cyclotrons of heavy ions at the Flerov Laboratory of Nuclear Reactions. They also have collected the experience of vacuum systems’ design of the number of projects for design of new cyclotrons or their upgrade. The simulation programs estimate ion beam losses and the beam transmission efficiency respectively being based on the pressure distribution simulation in vacuum chambers of any arbitrary complex geometry and also on cross sections calculation for a recharge of ions in exchange reactions by electrons with molecules of the residual gas in a wide range of energies and masses of ions being accelerated. The DC-60 cyclotron has been successfully launched in September of 2006. The results of the simulation have good accordance to experimental measurements on the first accelerated ion beams. |