Further dynamic aperture studies on a wiggler-based ultra-low emittance damping ring lattice

Further dynamic aperture studies on an ultra-low emittance damping ring lattice are presented. A past conference paper[l explained how the fast damping rate, the low emittance an d the large dynamic aperture are acheived for this lattice. Dy-namic aperture improvement with octupole correction was also reported. In this paper the dynamic aperture improvement is emphasized with a more systematic derivation and study of the octupole correction. Also, the modified sextupole proposal of Cornacchia and Halbach[2] is applied to the damping ring lat-tice. I