Dependence of volume FEL (VFEL) threshold conditions on undulator parameters

1 First Lasing of Volume FEL ( VFEL ) at Wavelength Range λ ∼ 4 − 6 mm ⋆

Coherent Radiation Effects in the Lcls Undulator∗

For X-ray Free-Electron Lasers such as LCLS and TESLA FEL, a change in the electron energy while amplifying the FEL radiation can shift the resonance condition out of the bandwidth of the FEL. The largest sources of energy loss is the emission of incoherent undulator radiation. Because the loss per electron depends only on the undulator parameters and the beam energy, which are fixed for a give...

Design formulas for short - wavelength FELs

Simple formulas for optimization of VUV and X-ray SASE FELs are presented. The FEL gain length and the optimal beta-function are explicitly expressed in terms of the electron beam and undulator parameters. The FEL saturation length is estimated taking into account quantum diffusion in the undulator. Examples of the FEL optimization are given. Parameters of a SASE FEL, operating at the Compton w...

A method for measuring the FEL radiation power along an undulator

A highly desirable measurement in Free Electron Laser (FEL) experiments is the dependency of the radiation power along the undulator. Most designs of undulators prohibit detection of the radiation power within the undulator or extracting the electron beam at arbitrary positions. Transport of both, the radiation "eld and the electron beam, through the entire undulator, and thus an ongoing FEL in...

Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

We report experimental studies of the effect of undulator tapering on superradiance in a single-pass highgain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform an...