L. Schachter, PARTICLE-ACCELERATION IN AN ACTIVE MEDIUM, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 53(6), 1996, pp. 6427-6434
It is shown that a bunch of electrons which move in an active medium c
an be accelerated. The acceleration is proportional to the population
inversion and the number of electrons in the bunch. As reference we co
mpare the acceleration force with the deceleration experienced by the
same bunch as it traverses a dielectric and metallic medium.