Saturation dynamics in FEL and optical-klystron FEL devices

In this note we present an analysis of FEL saturation mechanisms, with particular attention to the case of optical-klystron (O.K.) devices operating with low energy e-beam in the single-passage configuration. We discuss the range of validity of already introduced FEL gain versus intensity saturation formulae and show that O.K. FEL saturation occurs in two distinct steps. In the first, the dispersive section is "turned-off," in the second, saturation in the conventional sense is reached.<
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