Edge radiation in an electron storage ring

At wavelengths long compared to the critical wavelength, the radiation emitted from a bending magnet edge in an electron storage ring may be brighter than standard synchrotron radiation. This "edge radiation" has a far-field distribution which is nearly independent of wavelength for a range of wavelengths. The minimum wavelength of this range is determined by the distance required to deflect an electron through an angle of order 1/gamma, where gamma is the relativistic mass factor. The maximum wavelength of this range results from apertures and destructive interference between the edge radiation sources at the opposite ends of the straight section.