Abstract
The interaction between high-brilliance electron beams and counterpropagating laser pulses produces x rays via Thomson backscattering. If the laser source is long and intense enough, the electrons of the beam can bunch on the scale of the emitted x-ray wavelength and a regime of collective effects can establish. In this case of dominating collective effects, the FEL instability can develop and the system behaves like a free-electron laser based on an optical undulator. Coherent x rays can be irradiated, with a bandwidth very much thinner than that of the corresponding incoherent emission. The emittance of the electron beam and the distribution nonuniformity of the laser energy are the principal quantities that limit the growth of the x-ray signal. In this work we analyze with a 3D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the x-ray spectra obtained. The scalings typical of the optical wiggler, characterized by very short gain lengths and overall time durations of the process, make possible considerable emission also in violation of the Pellegrini criterion for static wigglers. A generalized form of this criterion is validated on the basis of the numerical evidence.
Highlights
If the laser pulse is long enough, collective effects can establish and become dominant. The system in this range of parameters behaves like a free-electron laser, where the static wiggler is substituted by the optical laser pulse [14 –17]
We have shown that considerable coherent x-ray radiation is possible as a result of the collective interaction between an electron beam and a counterpropagating laser pulse
The result is an emission at least 2 order of magnitudes larger than the incoherent one and with a thinner and more peaked spectrum. The characteristics of this x-ray source are, a substantial improvement with respect to analogous incoherent sources based on the Thomson backscattering
Summary
A Thomson backscattering setup can be considered in principle as a source of intense x-ray pulses which is at the same time tunable and highly monochromatic. L =L , which is consistent with the gauge requirement r AL 0 Another interesting case is when the laser pulse is guided with a profile gx; y; z; t described by a step function of radius w0. We make at this point the basic assumption that the collective scalar and vector potentials ’xyzt and. Axyzt will be considered as a slowly varying function of all variables xyz and t and the collective potential A is perpendicular to the z-axis up to terms of the order of =LT. Ns xyzt is the number of electrons that satisfy the preceding inequality
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
