Explicit expressions for the average number of twisted photons radiated by a charged particle in an elliptical undulator classical approximation as well approach accounting quantum recoil are obtained. It is shown that radiation emitted moving along helix which evolves around axis specifying angular momentum obeys selection rule: m + n even number, where projection total photon and serial harmo...

The Linac Coherent Light Source (LCLS) is a SASE 1.5-15 Å x-ray Free-Electron Laser (FEL) facility [1]. Since an ultra-short intense bunch is used in the LCLS operation one might suggest that wake fields, generated in the vacuum chamber, may have an effect on the x-ray production because these fields can change the beam particle energies thereby increasing the energy spread in a bunch. At LCLS ...

* Corresponding author. Tel.: +301-405-4977. Email [email protected]. Abstract A diagnostic undulator is used to measure relative electron bunch lengths. The radiation produced by the short undulator is observed off-axis so that the beam is not interrupted. Wavelengths radiated which are longer than the bunch length are coherent and may be more intense than the shorter wavelengths by a facto...

We propose and analyze a regenerative-amplifier free-electron laser (FEL) to produce fully coherent, hard x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought...

The Linac Coherent Light Source is an x-ray freeelectron laser at the SLAC National Accelerator Laboratory, which is operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron radiation sources. At the low charge operation mode (20 pC), the xray pulse length can be <10 fs. In this paper we report our numerical optimizati...

The spectrum of angle-integrated undulator radiation displays a sharp edge at every harmonic photon energy. A technique utilizing this feature to measure minute changes in Kparameters of an undulator in a free-electron laser has been proposed. To date, this technique requires the use of crystal monochromators as bandpass filters whose energy centroid depends on the incident angle of the x-ray b...

An FEL utilizing a high energy, high current and low emittance beam to prtduce radiation shorter than 2 A is investigated in this paper. This device is an extension of the previously proposed 40 A Linac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier opera...

At present, the linac-based SASE process is the most promising approach to reaching x-ray wavelengths with a free-electron laser. In the Self-Amplified-SpontaneousEmission process the spontaneous radiation is amplified in the single pass of an electron beam through an undulator, and no mirrors are required. This is an essential requirement for x-ray FELs, since the reflectivity of mirrors decre...