Experimental system for studying the stimulated Cerenkov interaction

An experimental system has been developed in which momentum exchange between laser light and relativistic electrons is achieved using the stimulated Cerenkov interaction. The interaction occurs within a gas which retards the phase velocity of the light wave in order to allow wavevector matching with the electron velocity. Light at 1.06 μm from a 30-MW Nd:YAG laser intersects 50-100 MeV electrons at angles of 17-18 mrad in hydrogen or methane gases. A spectrometer magnet and scintillation detector system verifies the change of the electron beam energy spectrum in the presence of the laser and as a function of the refractive index of the gases. The electron beam transport, laser, gas cell, and detector systems are described. Experimental data obtained using this system are also given. Possible applications of this work include optical klystrons and laser-driven particle accelerators.