Effect of fringing fields in storage rings

Electron beams in storage rings of third-generation synchrotron radiation sources feature a low emittance and extended lifetime. The provision of such characteristics requires a detailed study of higher order effects related to magnetic fields and cooperative effects associated with beam density. Fringing fields, being an unavoidable attribute of magnets of any type, may significantly affect the beam dynamics, since they appear in equations of particle motion of first and higher orders. A simple technique for evaluating the effect of fringing fields on the beam dynamics is suggested. Numerical results obtained with this technique for the quadrupoles of the CANDLE storage ring 1] are reported.