The multi-cavity free-electron laser

Analysis is made of a free-electron laser with many optical cavities where the cavities communicate with each other, not optically, but through the electron beam. Analytic analysis is made in a one-dimensional, linear approximation. A general expression is given for the growth rate in the exponential (high current) regime. In the regime where lethargy is important expressions are given in the two opposite limits of small and large numbers of cavities and bunches. Numerical simulation results, still in the one-dimensional approximation, but including nonlinearities, are presented. Three examples of the multi-cavity free-electron laser (MC/FEL) are presented.