  Effective and accurate computer simulations are highly important in
accelerator design and production. The most difficult and important task in
cyclotron development is magnetic field simulations. It is necessary to achieve
the accuracy of the model that is higher than the tolerance for the magnetic
field in the real magnet. An accurate model of the magnet and other systems of
the cyclotron allows us to perform beam tracking through the whole accelerator
from the ion source to extraction. While high accuracy is necessary in the late
stages of research and development, high performance of the simulations and
ability to swiftly analyze and apply changes to the project play a key role in
the early stages of the project. Techniques and algorithms for high accuracy
and performance of the magnet simulations have been created and used for the
development of the SC202 cyclotron for proton therapy, which is under
production by collaboration between JINR (Dubna, Russia) and ASIPP (Hefei,
China).
