title: Raman and Thompson regimes of amplification in a wiggler with noncollinear laser and electron beams.
abstract: The collective and single-electron amplification regimes of a noncollinear free-electron laser (FEL) are studied within the framework of dispersion equations. In the limit of small-signal gain the growth rates and the conditions for self-amplified excitations are found for the collective (Raman) and single-electron (Thompson) regimes. The Raman regime is shown to be preferable for the coherent spontaneous second harmonic generation by ultrarelativistic electron beams. Raman excitations in a noncollinear FEL, e.g., in an FEL without inversion, are favored by the noncollinear geometry of the electron and the laser beams, and by the relativity of the beam electrons.
authors.affiliation: General Physics Institute RAS, 38 Vavilov Street, Moscow, 119991 Russia.
authors.forename: D N
authors.initials: DN
authors.lastname: Klochkov
authors.forename: A I
authors.initials: AI
authors.lastname: Artemiev
authors.forename: G
authors.initials: G
authors.lastname: Kurizki
authors.forename: Yu V
authors.initials: YV
authors.lastname: Rostovtsev
authors.forename: M O
authors.initials: MO
authors.lastname: Scully