ID modeling at the ALS

At the Advanced Light Source there are several projects being proposed that will require high field insertion devices. It is important that these devices do not significantly impact the performance of the machine. In particular they should not degrade the beam lifetime or injection efficiency. It is known that high field devices with large field roll off can impact the beam lifetime. It is therefore important to model the effect of the insertion devices including both transverse and longitudinal field roll off. In this paper we present the result of tracking studies using an explicit symplectic integrator with both transverse and longitudinal field roll off. The simulations show where sufficiently large field roll off will impact the beam lifetime.