Study of low /spl beta//sub y/ straight section in SPEAR 3

The SPEAR 3 light source has two 7.6 m straight sections one of which is available for new insertion devices (ID). By reducing the vertical /spl beta//sub y/ function at the center of the straight from 9.8 m to 1.5 m, the beam size can be decreased from 44 /spl mu/m to 17 /spl mu/m to reduce the ID gap, but the ID length may be limited by the increased /spl beta//sub y/ variation in the ID. Alternatively, a "double waist" optics with two symmetric low /spl beta//sub y/ locations and a chicane may be considered to implement two IDs. In this paper, we discuss the low /spl beta//sub y/ optics effects on the beam dynamic aperture, and the ID parameters needed to maximize photon flux density and brightness while maintaining electron beam lifetime.