Synchrotron radiation becomes coherent when the electron bunch length is smaller than the wavelength being emitted. In this regime, the radiating fields of individual electrons add in phase, producing an intensity that scales with the square of the number of electrons instead of linearly as is the case for the more familiar synchrotron emission. Since the number of electrons in a storage ring is typically billions, this enhancement can be enormous, as shown in the calculated CIRCE flux. The many orders of magnitude increase in far-IR intensity is the basis of our project and enables new kinds of science.

The power emitted by electrons in a storage ring is given by

CSR is not normally observed in storage rings becuase the vacuum chamber surrounding the electrons acts like a waveguide and does not propegate long enough wavelengths to support CSR from the typical farily long electron bunches. If the electron bunch length could be shortened enough, CSR will be emitted in a wavelength window between this vacuum chamber cutoff and the bunch length as shown in the calculation below. The actual expected flux values for CIRCE are shown in the flux page.

The 35th issue of the ICFA Beam Dynamics Newsletter includes over 100 pages about coherent synchrotron radiation, December 2004. Many articles are by CIRCE authors, with one paper describing the CIRCE proposed source.