Speaker
Jorge Vieira
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/I3.207.pdf
Optical control of the topology of plasma accelerators
J. Vieira1, J.T. Mendonça1, F. Quéré2
1
GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de
Lisboa, Lisbon, Portugal
2
LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91 191 Gif-sur-Yvette, France
Exploring advanced plasma based accelerators is important research issue, as they can lead to
more compact particle accelerators and light source for scientific and societal applications.
One of the most advanced schemes is the laser wakefield accelerator, which employs laser
pulses to excite the plasma.
A twisted laser pulse driver with orbital angular momentum can change the spatial structure
of the plasma wave dramatically, in comparison to Gaussian drivers. Plasma waves driven by
intense twisted light acquire a doughnut shape, which are useful to accelerate ring shaped
electron beams, which could be used as a lens, being also suited for high gradient positron
acceleration, providing a solution to an ongoing outstanding challenge. These results point
towards a remarkable property, specific of plasma accelerators, which is the topological
flexibility of plasma wakefields, which may provide unprecedented control over the internal
degrees of freedom of relativistic beams. We illustrate the concept with lasers characterized
by helical intensity profiles, also known as light springs. This approach is motived by the
recent advances on ultra-fast beam shaping, which provide new paths to produce ultra-intense
lasers with unusual spatiotemporal properties. We show that light springs can drive relativistic
twisted plasma wakefields, which carry orbital angular momentum themselves. In the
nonlinear regime, these twisted wakes can generate and accelerate relativistic vortex electron
beams, which have quantized orbital angular momentum levels, although they are of a purely
classical origin. These beams are challenging to produce by other means, and could be already
of interest to the communities exploiting particle beams to probe matter. We confirm our
theoretical results with 3D particle-in-cell simulations in Osiris.
[1] J. Vieira, J.T. Mendonça, Phys. Rev. Lett. 112 215001 (2014).
[2] G. Pariente, F. Quéré, Optics Lett. 40, 2037-2040 (2015).
