Background: A compact cyclotron with energy of 11 MeV and current of 50 ?A is under construction in Institute of Fluid Physics of China Academy of Engineering Physics. The compact cyclotron is developed for medical isotope production. Purpose: To minimize the cost and to shorten the time of the development of the compact cyclotron

a lot of efforts were dedicated to the physics design of the compact cyclotron. Methods: Physics design of the main magnet was performed using TOSCA software

and start-to-end beam dynamics design was performed using home-made software CYCDYN. Results: Physics design of the compact cyclotron was given in details. Design methods and results of the main subsystems (including ion source

radial sector focusing magnet

RF cavity

central region and extraction system) were also given in this paper. Conclusion: Now commissioning of this cyclotron has been finished

and the goal for extracting proton beams of 11 MeV and 50 uA on average has been achieved. Physics design of the cyclotron has been validated by the commissioning results.Cited