CERENKOV LASERS

Abstract
A Cerenkov laser consists of an electron beam, a dielectric resonator, and suitable output coupling optics. The beam may pass directly through the dielectric at greater-than-light speed for that medium, in which case it will emit spontaneous Cerenkov radiation. If , in addition, there are mirrors forming an optical cavity, the reflected radiation stimulates further Cerenkov emission, and gain can result. In order to achieve gain, however, the beam velocity spread must be kept very low and hence in this most elementary case a gaseous dielectric and a highly energetic beam is needed. The Cerenkov threshold energy γ_T expressed in terms of the index of refraction n is given by : γ_T = n/ √n² -1 When typical gasses at moderate pressure are considered, γ_T will range between 20 and 200. It is also possible to propagate a beam through a channel or near to the surface of a dielectric. In this case the threshold energy is greatly reduced. Substantial power in the lower mm wavelength range can be obtained from devices driven by beams in the 100-200 KV range.