Generation of electron high energy beams with a ring-like structure by a dual stage laser wakefield accelerator

Spesyvtsev, R. and Brunetti, E. and Vieux, G. and Shahzad, M. and Maitrallain, A. and Yoffe, S. and Ersfeld, B. and Kornaszewski, A. and Streeter, M. J. V. and Finlay, O. and Ma, Y. and Kettle, B. and Dann, S.J.D. and Albert, F. and Bourgeois, Nicola and Cipiccia, S. and Cole, J.M. and Gerstmayr, E. and González, I.G. and Higginbotham, A. and Hussein, A.E. and Falk, K. and Krushelnick, K. and Lemos, N.C. and Lopes, N.C. and Lumsdon, C. and Lundh, O. and Mangles, S. P. D. and Najmudin, Z. and Rajeev, P. P. and Smid, M. and Symes, D.R. and Thomas, A.G.R. and Jaroszynski, D.A. (2019) Generation of electron high energy beams with a ring-like structure by a dual stage laser wakefield accelerator. In: Relativistic Plasma Waves and Particle Beams as Coherent and Incoherent Radiation Sources III. SPIE, Bellingham, WA.

[img]
Preview
Text (Spesyvtsev-etal-SPIE-2019-Generation-of-electron-high-energy-beams-with-a-ring-like-structure)
Spesyvtsev_etal_SPIE_2019_Generation_of_electron_high_energy_beams_with_a_ring_like_structure.pdf
Accepted Author Manuscript

Download (848kB)| Preview

    Abstract

    The laser wake-field accelerator (LWFA) traditionally produces high brightness, quasi-monoenergetic electron beams with Gaussian-like spatial and angular distributions. In the present work we investigate the generation of ultra-relativistic beams with ring-like structures in the blowout regime of the LWFA using a dual stage accelerator. A density down-ramp triggers injection after the first stage and is used to produce ring-like electron spectra in the 300 – 600 MeV energy range. These well defined, annular beams are observed simultaneously with the on-axis, high energy electron beams, with a divergence of a few milliradians. The rings have quasi-monoenergetic energy spectra with an RMS spread estimated to be less than 5%. Particle-in-cell simulations confirm that off-axis injection provides the electrons with the initial transverse momentum necessary to undertake distinct betatron oscillations within the plasma bubble during their acceleration process.