FEL operation in a magnetostatic field produced by current-carrying linear wire

It is shown that free-electron laser (FEL) operation is possible in a magnetostatic field produced by a dc-current-carrying long linear wire. A single-particle approach is used to derive the small-signal gain equation in this configuration. The maximum value of the small-signal gain is proportional to the cube of the interaction region length in our case, as in the ordinary circularly polarized FEL.<
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