Normal modes propagation in a helical free-electron laser with an axial guide field

Abstract

± of the quadratic Hamiltonian are analyzed numerically in both the normal and reversed-field configurations for different values of the ratio w/ 0. The electron trajectories are thus discussed. It is found that pseudo-circular and elliptic trajectories are characterizing both group-I and reversed-field group-II modes while the motion in the normal group-II mode is much more complicated.]]>

Geometric Phases for Wave Packets of the Landau Problem

“…where the star denotes complex conjugate and setting m, and the cyclotron frequency ω 0 to unity, we have The ground state of the density operator N B + in each Landau level n is specified by (14) and (15):…”

“…of fact, this formalism proved to be efficient in treating the problem of particle dynamics in a free-electron laser consisting of a helical wiggler magnetic field and a uniform guide field [13][14][15]. Even though the geometric phases for wave packets of charged particles moving in a constant magnetic field were very seldom considered in the literature [16,17] because this represents a rather simple and realizable physical situation, they can occur for time dependant systems like spin in a uniform magnetic field.…”