Resistive-wall impedance effects for the new KEK Light Source

8th International Particle Accelerator Conference

Nakamura, N.^1,2

High Energy Accelerator Research Organization (KEK), Tsukuba, Japan^1

Graduate University for Advanced Studies (SOKENDAI), Tsukuba, Japan^2

关键词: Coupled bunch instabilities;    Heating power;    Longitudinal impedances;    Per unit length;    Resistive walls;    Resistive-wall impedance;    Transverse feedback system;    Transverse impedance;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/874/1/012069/pdf
DOI  :  10.1088/1742-6596/874/1/012069

来源: IOP

【 摘 要 】

Effects of resistive-wall (RW) impedance on a 3-GeV storage ring of the KEK Light Source (KEK-LS) are presented. Cu sheets used for in-vacuum undulators (IVUs) are regarded as the main source of the RW impedance. Although the calculated heating power per unit length due to the longitudinal impedance is more than 20 W, it is not serious for the water-cooled IVUs. The maximum growth rate of the coupled-bunch instability caused by the transverse impedance is calculated and as a result, a transverse feedback system with the damping rate of more than 104s-1is required for the instability suppression. NEG coating of about 1 μm can be used for the KEK-LS vacuum pipe because increase of the heating power due to the NEG coating impedance is small and the effect on the transverse coupled-bunch instability is negligible.