ELECTRON-BEAM-INDUCED SUPERRADIANT EMISSION FROM A GRATING

An alternative mechanism for Smith-Purcell radiation is proposed. This mechanism may have relevance to recent reports of higher radiation power. The electron beam excites resonant transitions of atomic quantum levels in the optical grating material by the fields of the traversing electrons. The dipole moments of all the atoms which are excited by the same electron radiate in phase with each other and produce ''super-radiant radiation.'' To calculate the radiant intensity due to this process we first calculate the dipole moments of the atoms excited by the classical electrical field of the traversing electron. Assuming that the dipole oscillations are dominated by a collision time T2 we calculate the classical radiant intensity from the optical gratings due to this process. Sample numerical calculations based on a ruby grating result in substantial radiation levels.