Morozov, N.A. Bi, Y.F. Chen, G. Chen, Y. Ding, K.Z. Du, Sh. Feng, H. Ge, J. Karamyshev, O. Karamysheva, G.A. Li, J. Samsonov, E.V. Shirkov, G. Song, Y. Zheng, J. Zhou, J. JACoW Geneva, Switzerland 978-3-95450-167-0 10.18429/JACoW-Cyclotrons2016-THP20 English 353-355 THP20 cyclotron proton extraction simulation plasma Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-Cyclotrons2016-THP20 http://jacow.org/cyclotrons2016/papers/thp20.pdf The superconducting cyclotron SC200 for proton therapy is designing by ASIPP (Hefei, China) and JINR (Dubna, Russia) will be able to accelerate protons to the energy 200 MeV with the maximum beam current of 1 μA. A conceptual design study with 3D codes for the superconducting cyclotron magnet has been carried out during 2015-16 at ASIPP and JINR. The main design considerations are reviewed. The results obtained by numerical field computation for a suitable choice of design parameters are presented. Results of numerical calculations are the basis for technical design of SC200 cyclotron.