9 research outputs found
Focussing effects in laser-electron Thomson scattering
We study the effects of laser pulse focussing on the spectral properties of
Thomson scattered radiation. Modelling the laser as a paraxial beam we find
that, in all but the most extreme cases of focussing, the temporal envelope has
a much bigger effect on the spectrum than the focussing itself. For the case of
ultra-short pulses, where the paraxial model is no longer valid, we adopt a
sub-cycle vector beam description of the field. It is found that the emission
harmonics are blue shifted and broaden out in frequency space as the pulse
becomes shorter. Additionally the carrier envelope phase becomes important,
resulting in an angular asymmetry in the spectrum. We then use the same model
to study the effects of focussing beyond the limit where the paraxial expansion
is valid. It is found that fields focussed to sub-wavelength spot sizes produce
spectra that are qualitatively similar to those from sub-cycle pulses due to
the shortening of the pulse with focussing. Finally, we study high-intensity
fields and find that, in general, the focussing makes negligible difference to
the spectra in the regime of radiation reaction.Comment: 14 pages, 17 figure
Magnetic mirror cavities as THz radiation sources and a means of quantifying radiation friction
We propose a radiation source based on a magnetic mirror cavity. Relativistic
electrons are simulated entering the cavity and their trajectories and
resulting emission spectra are calculated. The uniformity of the particle
orbits is found to result in a frequency comb in terahertz range, the precise
energies of which are tuneable by varying the electron's -factor. For
very high energy particles radiation friction causes the spectral harmonics to
broaden and we suggest this as a possible way to verify competing classical
equations of motion.Comment: 8 pages, 10 figure