Study of collective effects in a low-emittance PEP lattice

This paper summarizes the work on the collective effects studied during the previously described low-emittance operation of PEP. These studies looked at the single bunch and multi-bunch current limits consistent with stable beam operation. The lower than expected current limits and observed coherent beam oscillations, together with methods of countering them, were considered at a recent SSRL workshop. A result of these studies has been that the lower momentum compaction factor and large beta function variations of the low-emittance lattice (a common feature of all proposed high-energy radiation sources) contribute to enhanced collective effects, limiting the early achievable beam intensity to less than the desired 100 mA. The calculational models, especially because of the uncertainty of the beam impedance models, have limited predictability for these effects and will benefit from continued studies of this kind