Chirped and modulated electron pulse free electron laser techniques

A potential method to improve the free electron laser’s output when the electron pulse has a large energy spread is investigate and results presented. A simplified model is the first given, in which there are a number of linearly chirped beamlets equally separated in energy and time. By using chicanes, radiation from one chirped beamlet is passed to the next, helping to negate the effect of the beamlet chirps and maintaining resonant interactions. Hence the addition of chicane allow the electrons to interact with a smaller range of frequencies (Δω<2ργr), sustaining the FEL interaction. One method to generate such a beamlet structure is presented and is shown to increase FEL performance by two orders of magnitude.