Focusing of infrared edge and synchrotron radiation

Abstract

The focusing of edge and synchrotron radiation from a zero-emittance electron beam is modeled for an optical system consisting of a reflecting sphere with an aperture. With a large aperture, edge radiation is imaged to a spot size ≪ λγ , where λ is the wavelength and γ the relativistic factor of the electrons. When the aperture size equals the opening angle, ordinary synchrotron radiation may be focused to a spot size of ρ 1/3 λ 2/3 , where ρ is the radius of curvature of the electron orbit. For apertures sufficiently large to collect the central radiation cone, the peak brightness of edge radiation is nearly independent of the aperture angle, and inversely proportional to the square of the wavelength. For an aperture size equaling the opening angle, the peak brightness of a focused spot of ordinary synchrotron radiation is 4–5 times as large as that of edge radiation. For both edge and ordinary synchrotron radiation, a comparable flux may be concentrated into phase space volumes of ∼8 λ 2 . The implications of these computations upon the siting of an infrared beamline are also discussed.