Low-alpha optics design for SSRF

In this paper, short pulse radiation in Shanghai Synchrotron Radiation Facility （SSRF） is generated by the low momentum compaction factor （ac） optics, and three kinds of the low- ac optics are found, with the very low ac being adopted by reducing dispersion in the straight section to negative value in the SSRE Energy acceptance is selected as objective functions in nonlinear optimization rather than the second order ac or other nonlinear driving terms. The optimal result is improved step-by-step by randomly setting harmonic sextupole strengths. Two optics modes, i.e. low positive ac and low negative ac, are analyzed. In order to get a large energy acceptance and only one stable point in longitudinal phase space, the low negative ac optics is taken as an operation mode for the short pulse radiation in the SSRF.