Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor...Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor(Q_(0)).The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing(BCP)and electropolishing(EP),and their E_(acc) exceeded40 MV/m.Such a high E_(acc) may result from the cold EP with more uniform removal.BCP is easy,cheap,and rough,whereas EP is complicated,expensive,and precise Therefore,the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities.Medium temperature(mid-T)furnace baking was also conducted,which demonstrated an ultrahigh Q_(0) of 8×10^(10) at 22 MV/m for both cavities,and an extremely low BCS resistance(R_(BCS))of~1.0 nΩwas achieved a2.0 K.展开更多
Higher-order mode（HOM） based intra-cavity beam diagnostics has been proved effective and convenient in superconducting radio-frequency（SRF） accelerators.Our recent research shows that the beam harmonics in the bun...Higher-order mode（HOM） based intra-cavity beam diagnostics has been proved effective and convenient in superconducting radio-frequency（SRF） accelerators.Our recent research shows that the beam harmonics in the bunch train excited HOM spectrum,which have much higher signal-to-noise ratio than the intrinsic HOM peaks,may also be useful for beam diagnostics.In this paper,we will present our study on bunch train excited HOMs,including a theoretical model and recent experiments carried out based on the DC-SRF photoinjector and SRF linac at Peking University.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB25000000)the National Natural Science Foundation of China(No.12075270)the Platform of Advanced Photon Source Technology R&D。
文摘Two 650 MHz single-cell superconducting radio-frequency(SRF)cavities used for the Circular Electron Positron Collider(CEPC)were studied to achieve a high accelerating gradient(E_(acc))and high intrinsic quality factor(Q_(0)).The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing(BCP)and electropolishing(EP),and their E_(acc) exceeded40 MV/m.Such a high E_(acc) may result from the cold EP with more uniform removal.BCP is easy,cheap,and rough,whereas EP is complicated,expensive,and precise Therefore,the combination of BCP and EP investigated in this study is suitable for surface treatments of mass SRF cavities.Medium temperature(mid-T)furnace baking was also conducted,which demonstrated an ultrahigh Q_(0) of 8×10^(10) at 22 MV/m for both cavities,and an extremely low BCS resistance(R_(BCS))of~1.0 nΩwas achieved a2.0 K.
基金Supported by National Natural Science Foundation of China(11275014)
文摘Higher-order mode（HOM） based intra-cavity beam diagnostics has been proved effective and convenient in superconducting radio-frequency（SRF） accelerators.Our recent research shows that the beam harmonics in the bunch train excited HOM spectrum,which have much higher signal-to-noise ratio than the intrinsic HOM peaks,may also be useful for beam diagnostics.In this paper,we will present our study on bunch train excited HOMs,including a theoretical model and recent experiments carried out based on the DC-SRF photoinjector and SRF linac at Peking University.
