A.Doria, G.P. Gallerano, E. Giovenale, G. Messina, V.B. Asgekar (a), G. Doucas (b), M.F. Kimmitt (c), J.E. Walsh (d)
ENEA - Divisione Fisica Applicata - P.O. Box 65 - 00044 Frascati - Italy; (a)University of Pune, INDIA; (b)University of Oxford, UK; (c)University of Essex, UK; (d)Dartmouth College, Hanover (NH) USA;
A metal grating (Smith-Purcell) experiment is under way at ENEA-Frascati in the framework of a collaboration with the University of Oxford, the University of Essex and the Dartmouth College Hanover (NH). The experiment is driven by a 2.3 MeV S-band microtron, providing 10 ps electron bunches with 4 A peak current, and utilizes a 4 mm period grating to generate coherent mm and sub-mm radiation. Shorter period gratings and electron energies up to 5 MeV are also available and will enable operation in the far infrared region down to 50 microns wavelength. The position of the grating and the geometry of the collecting optics can be varied for a systematic investigation of the angular distribution of the emitted radiation.
In this paper we report first coherent spontaneous emission measurements at wavelengths around 1 mm. A clean spectral output has been observed by means of a metal-mesh Fabry-Perot interferometer. The power dependence of the emitted radiation on the electron beam current and its distance from the grating surface, are discussed together with an analysis of the spectral features as a function of the azimuthal angle.
