SRF2013 - List of Authors (Cai, Y.)

Paper	Title	Page
THP042	High Frequency SRF Cavity Study for Bunch Shortening in PEPX	998
	L. Xiao, K.L.F. Bane, Y. Cai, X. Huang, C.-K. Ng, A. Novokhatski, L. Wang SLAC, Menlo Park, California, USA
	The proposed PEPX is a diffraction limited storage ring light source, or “ultimate storage ring (USR)”, which can be built in the PEP tunnel at SLAC. The 4.5GeV PEPX design based on the USR with a natural emittance about 10pm-rad can be used to drive a high-gain soft X-ray FEL. In order to achieve a desired high peak current over 300A for the FEL, the bunch length is reduced to 1ps from 10ps through a set of multi-cell SRF cavities working at 1.428GHz in CW mode, providing about 300MV RF gradient. In this paper, the 1.5GHz JLAB C100 cavity for the CEBAF upgrade and 1.3GHz Cornell ERL cavity are investigated for its application to PEPX-FEL. The simulation results show that the beam induced high order modes (HOM) in the C100 cavities will limit the threshold of the beam current for PEPX-FEL. And the same pass band modes (SPM) in the cavities are strongly trapped, and thus generate unacceptable beam power once they hit the beam resonances. Therefore, a 5-cell with a larger iris cavity design instead of the C100 7-cell design is proposed. Preliminary results on the rf parameters of the cavity, HOM damping and beam dynamics studies will be presented.

Paper

Title

Page

High Frequency SRF Cavity Study for Bunch Shortening in PEPX

998

L. Xiao, K.L.F. Bane, Y. Cai, X. Huang, C.-K. Ng, A. Novokhatski, L. Wang
SLAC, Menlo Park, California, USA

The proposed PEPX is a diffraction limited storage ring light source, or “ultimate storage ring (USR)”, which can be built in the PEP tunnel at SLAC. The 4.5GeV PEPX design based on the USR with a natural emittance about 10pm-rad can be used to drive a high-gain soft X-ray FEL. In order to achieve a desired high peak current over 300A for the FEL, the bunch length is reduced to 1ps from 10ps through a set of multi-cell SRF cavities working at 1.428GHz in CW mode, providing about 300MV RF gradient. In this paper, the 1.5GHz JLAB C100 cavity for the CEBAF upgrade and 1.3GHz Cornell ERL cavity are investigated for its application to PEPX-FEL. The simulation results show that the beam induced high order modes (HOM) in the C100 cavities will limit the threshold of the beam current for PEPX-FEL. And the same pass band modes (SPM) in the cavities are strongly trapped, and thus generate unacceptable beam power once they hit the beam resonances. Therefore, a 5-cell with a larger iris cavity design instead of the C100 7-cell design is proposed. Preliminary results on the rf parameters of the cavity, HOM damping and beam dynamics studies will be presented.