Noninvasive beam position, size, divergence and energy diagnostics using diffraction radiation

Abstract

We have developed non-invasive methods to measure the size, position, divergence and energy of a relativistic charged particle beam using diffraction radiation (DR). The DR is produced by the interaction of the beam fields with single or multiple apertures inclined at an angle of 45° with respect to the beam velocity, ν. We propose to utilize the near field image, far field angular distribution (AD) and polarization of backward DR, observed at 90° with respect to ν, to diagnose the beam. Unlike transition radiation (TR), the AD of DR is generally a function of the beam’s transverse size, ρ and position of the centroid relative to the center of the aperture, b as well as the divergence, s and energy, E. We show how the effects of ρ and b on the AD can be minimized or maximized by proper choice of the ratio: R=a/γƛ, where a is the distance from the edge of the aperture to the center of the beam, ƛ=λ/2π, λ is the observed wavelength and γ is the Lorentz factor. For example, when R<1, the AD of DR is insensit...