J.H. Brownell, S. Trotz, J. Walsh; G. Doucas
Dept. of Physics and Astronomy, Dartmouth College, Hanover, NH 03755; University of Oxford
Radiation produced by highly relativistic electrons passing over a diffraction grating has not yet been completely characterized. This is due in part to complications that arise in the standard modal expansion method of computation if the emitted wavelength is much smaller than the grating period. This limit will be encountered in the relativistic regime at small angles of emission. In contrast, the surface current model [Phys. Rev. E, 57, 1075, 1998] is well behaved in the highly relativistic regime. The model predicts that the maxima of the reciprocal wavelength and the intensity in the emission spectrum is determined by the grating period, the blaze angle, the electron impact parameter, the beam energy, and the length of the beam micro pulse bunch. In addition the model predicts a discrete set of emission orders. The radiation pattern from an echelle type grating has the startling feature that all orders are emitted in the same direction. With appropriate choice of period and blaze angle, many orders can be emitted with comparable intensity. Analysis of the echelle type grating will be presented.
