STIMULATED COHERENT EMISSION FROM SHORT ELECTRON BUNCHES IN FREE-SPACE

The peculiarities have been studied of the stimulated emission of a sh eetlike electron bunch of finite length and transverse size passing th rough an undulator field. A two-dimensional model, based on a nonstati onary parabolic equation, has been formulated and includes the effects of slippage and optical guiding as well as transverse electromagnetic energy diffraction and dissipation. It is shown that the emission fro m the electron bunch is composed of short coherent pulses (superradiat ion pulses) which are diffracted after escaping from the channel forme d by the electron bunch.