Stochasticity caused by radiation misalignment in magnetized free-electron lasers with trapped particles

A theoretical and numerical analysis is performed on the conditions under which electron stochastic detrapping due to small misalignments between the laser wave vector and the global symmetry of the system occurs in magnetically guided free-electron lasers. In particular, it is shown that the threshold for stochasticity is only weakly dependent on the transverse momentum of trapped particles, which allows some simple general conclusions to be drawn regarding the maximum values allowed for this misalignment.