## Coherent Synchrotron Radiation in Multiply-Connected Vacuum Chamber

Coherent synchrotron radiation (CSR) in a singly-connected vacuum chamber is, as it is well known, strongly suppressed for harmonics n{sub cr} less-than-or-equal to (R/h){sup 3/2}, where R is the radius of curvature and h is characteristic transverse dimension. If, however, the vacuum chamber has a multiply-connected topology, the critical frequency is zero and this restriction is not valid anymore. Estimation for radiated power in a multiply-connected chamber is presented here including CSR in electrostatic separator and at the LHC collider.