  Theory predicts that Coherent Synchrotron Radiation (CSR) in electron storage
rings should appear in whispering gallery modes. In an idealized model these
are resonances of the vacuum chamber that are characterized by their high
frequencies and concentration of the field near the outer wall of the chamber.
  The resonant modes imply a series of sharp peaks in the frequency spectrum of
CSR, and very long wake fields which lead to interbunch communication.
  Theory and experimental evidence for this behavior will be reviewed.
