Abstract
An ultrarelativistic electron beam passing through an intense laser pulse emits radiation around its direction of propagation into a characteristic angular profile. Here we show that measurement of the variances of this profile in the planes parallel and perpendicular to the laser polarization, and the mean initial and final energies of the electron beam, allows the intensity of the laser pulse to be inferred in way that is independent of the model of the electron dynamics. The method presented applies whether radiation reaction is important or not, and whether it is classical or quantum in nature, with accuracy of a few per cent across three orders of magnitude in intensity. It is tolerant of electron beams with broad energy spread and finite divergence. In laser-electron beam collision experiments, where spatiotemporal fluctuations cause alignment of the beams to vary from shot to shot, this permits inference of the laser intensity at the collision point, thereby facilitating comparisons between theoretical calculations and experimental data.
Highlights
Electromagnetic fields of extraordinary strength are produced at the focus of modern high-power lasers [1], inducing nonlinear classical, even quantum, dynamics of particles and plasmas [2,3,4]
We show that measurement of the variances of this profile in the planes parallel and perpendicular to the laser polarization, and the mean initial and final energies of the electron beam, allows the intensity of the laser pulse to be inferred in a way that is independent of the model of the electron dynamics
Examining our method in a more realistic scenario, where the tight focusing of the laser and finite size of the electron beam are taken into account, we find that it yields a model-independent estimate of the laser intensity, averaged over the electron-beam size
Summary
Electromagnetic fields of extraordinary strength are produced at the focus of modern high-power lasers [1], inducing nonlinear classical, even quantum, dynamics of particles and plasmas [2,3,4]. We derive analytical predictions for the size of the radiation profile and the energy change of the electron beam, treating the laser as a pulsed plane electromagnetic wave, that can be combined so as to eliminate an explicit dependence on classical radiation reaction We show that this model-independence applies to a high degree of accuracy under quantum models of radiation reaction as well. This permits measurement of the peak intensity, if the electron beam is well characterized, stable, and radially smaller than the laser focal spot size; with spatiotemporal fluctuations taken into account, our method provides a powerful constraint on the intensity at the point of interaction, for each individual collision This is complementary to methods aimed at determining the peak intensity itself, by measurement of the ionization level of heavy atoms [15], Thomson scattering of low-energy electrons present in the focal volume [16], or detailed characterization of the laser structure, gathered over hundreds of shots [17]. Our method provides a means of determining the shot-to-shot overlap between the laser pulse and electron beam
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 callDisclaimer: 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.
