Electron acceleration using radially polarized laser pulses

Our group is also investigating how the interaction between an ultra-intense laser pulse and a solid target can be used to produce a femtosecond electron source, possibly at high repetition rate. The idea is that when the laser impinges on the solid target, it rips electrons from the front surface and propels them in the laser field with an relatively high kinetic energy. Electrons can then surf the laser wavefronts and be accelerated by the laser itself in a process known as “vacuum laser acceleration”. We have performed experiments and simulations of this process showing that electrons can be accelerated to MeV energies in beams containing 100 pC charge. The electron beams, until now, were very divergent and difficult to use for applications. Recently, we have considered the case of radially polarized laser pulses. Such exotic pulses have the advantage that at focus, the electric field acquires a longitudinal component of the field (instead of transverse for a regular plane wave). The longitudinal can in principle accelerate electrons better and produce a more collimated electron beam.

Related publications:

Interaction of ultraintense radially-polarized laser pulses with plasma mirrors”, N. Zaim et al., submitted (2020)

Few-cycle laser wakefield acceleration on solid targets with controlled plasma scale length”; N. Zaïm, F. Böhle, M. Bocoum, A. Vernier, S. Haessler, X. Davoine, L. Videau, J. Faure and R. Lopez-Martens, Physics of Plasmas 26, 033112 (2019)

Relativistic acceleration of electrons injected by a plasma mirror into a radially polarized laser beam; N. Zaïm, M. Thévenet, A. Lifschitz and J. Faure, Phys. Rev. Lett. 119, 094801 (2017)

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors”; M. Thévenet, A. Leblanc, S. Kahaly, H. Vincenti, A. Vernier, F. Quéré and J. Faure; Nature Physics 12, 355 (2016)

On the physics of electron ejection from laser-irradiated overdense plasmas, M. Thévenet, H. Vincenti and J. Faure; Phys. Plasmas 23, 063119 (2016)

Figure: Image of a radially polarized pulse at focus: the electric field oscillates radially, following a radial symmetry. The focal spot has a doughnut shape.