Zhang, J.Q. Han, R. Li, S.P. JACoW Publishing Geneva, Switzerland 978-3-95450-216-5 10.18429/JACoW-eeFACT2018-WEPAB05 English 282-285 WEPAB05 cryogenics collider cryomodule cavity booster Contribution to a conference proceedings 2019 2019-04 https://doi.org/10.18429/JACoW-eeFACT2018-WEPAB05 http://jacow.org/eefact2018/papers/wepab05.pdf The CEPC has two rings, the booster ring and the collider ring. There are 432 superconducting cavities in total. In the booster ring, there are 96 ILC type 1.3 GHz 9-cell superconducting cavities; eight of them will be packaged in one 12-m-long module. There are 12 such modules. In the collider ring, there are 240 650 MHz 2-cell cavities; six of them will be packaged in one 11-m-long module. There are 40 of them. All the cavities will be cooled in a liquid-helium bath at a temperature of 2K to achieve a good cavity quality factor. The cooling benefits from helium II thermo-physical properties of large effective thermal conductivity and heat capacity as well as low viscosity and is a technically safe and economically reasonable choice. The 2K cryostat will be protected against heat radiation by means of two thermal shields cooling with 5-8K helium as well as 40-80K helium from a refrigerator. There are 4 cryo-stations along the 100km circular collider with the physical design of double ring. Generally, each cryo-station is supplied from a common cryogenic plant, with one refrigerator and one distribution box. The cooling capacity of each refrigerator is 18kW @ 4.5K.