Lv, Y.L. An, S. Cui, T. Ge, T. Ji, B. Jia, X.L. Wang, S.L. Zhang, T.J. JACoW Publishing Geneva, Switzerland 978-3-95450-205-9 10.18429/JACoW-Cyclotrons2019-TUP031 English 230-232 TUP031 cyclotron proton radiation ion-source cavity Contribution to a conference proceedings 2020 2020-06 https://doi.org/10.18429/JACoW-Cyclotrons2019-TUP031 http://jacow.org/cyclotrons2019/papers/tup031.pdf The proton irradiation facility for space science research and application consists of a 50 MeV proton cyclotron, two beam lines and two radiation effect simulation experimental target station. The 50 MeV proton cyclotron (CYCIAE-50) is a compact negative hydrogen ion cyclotron with the proton beam energy from 30 MeV to 50 MeV, and the beam intensity is from 10 nA to 10 uA. The cyclotron is about 3.2 m in diameter, 3.5 m in total height and 80 tons in total weight. The diameter of the pole is 2000 mm, the outer diameter of the yoke is 3200 mm, and the height of magnet is 1500 mm. The cyclotron uses an external multi-cusp H⁻ ion source. Then the H⁻ beam is injected into the accelerating orbit by the spiral inflector. The cyclotron frequency is about 16 MHz. The RF system is a pair of λ/2 RF cavities driven by a 25 kW transmitter. The fourth harmonic accelerating frequency is about 65 MHz. The proton beam is extracted by a single movable stripping carbon foil with the stripping extraction efficiency of 99%. The 50 MeV cyclotron has now been designed in detail, and its main components, such as the main magnets and RF cavities, are being manufactured in the factories in China.