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This paper introduces a generalized, linear, three-dimensional model of the FEL amplifier. This 3-D model that is represented by a matrix gain-dispersion equation is valid in the various FEL gain regimes; the low and high gain regimes and the space-charge dominated regimes . It includes electron-beam longitudinal velocity spread effects that are caused by(More)
unity, in which case we have parametric gain, i.e., image intensification. The factor exp[2i(Ao,5 )l] in (A22) is very nearly unity in most cases since 1, in practice, will probably be limited to a few centimeters. It can easily be shown, however, that a subsequent stage of parametric mixing, which is needed to regain the image, will introduce the(More)
1098-4402= A formulation for the characterization of superradiant and stimulated-superradiant radiative emission from bunched electron beams is presented. The radiation is characterized in terms of power and spectral power per radiation mode, which provide a measure of the useful spatially coherent radiation power and spectral power emitted by a radiation(More)
The design and measurements of a resonator operating near 100 GHz and intended for use in a tandem FEL are presented. The designed resonator employs two parallel curved plates as a waveguide. In FEL operation the TE,, mode is excited. The resonator employs two wave splitters as reflectors. The wave splitters are segments of an overmoded rectangular(More)
The e-beam and radiation wave dynamics in the radiating and nonradiating beam transport sections of free electron lasers (FELs) are analyzed in the collective regime by use of a single transverse mode linear response formulation. This is employed to derive conditions for coherent operation of seeded high-gain FELs. It is shown that the level of incoherent(More)
Microbunching of a relativistic electron beam into a helix is examined analytically and in simulation. Helical microbunching is shown to occur naturally when an e beam interacts resonantly at the harmonics of the combined field of a helical magnetic undulator and an axisymmetric input laser beam. This type of interaction is proposed as a method to generate(More)
We present a theoretical model for longitudinal collective Coulomb interactions in a charged-particle beam. It suggests a possibility to control and reduce optical frequency shot-noise current in accelerated electron beams. For short interaction lengths, the model describes well coherent optical transition radiation effects observed in SLAC LCLS and in(More)
Radiative emission from the magnetic moments of the spins of an electron beam has never been observed directly, because it is fundamentally much weaker than the electric charge emission. We show that the detectivity of spin-flip and combined spin-flip-cyclotron-resonance-emission radiation can be substantially enhanced by operating with ultrashort(More)
We present results of an experiment where, using a 200 GW CO_{2} laser seed, a 65 MeV electron beam was decelerated down to 35 MeV in a 54-cm-long strongly tapered helical magnetic undulator, extracting over 30% of the initial electron beam energy to coherent radiation. These results, supported by simulations of the radiation field evolution, demonstrate(More)