Speaker
Description
We propose and test a multi-step preliminary analytical procedure that tailors the initial
density fn0 of a cold diluted collisionless plasma to a very short and intense plane-wave
laser pulse travelling in the z direction, so as to maximize the early laser wakefield acceleration
(LWFA) of bunches of plasma electrons self-injected in the plasma wave (PW) by the
first wave-breaking (WB) at the density down-ramp. The procedure partially inverts the
determination of the motion of the plasma electrons for a given pulse and (for simplicity,
slowly varying) fn0(Z): the motion of every infinitesimal layer of electrons having coordinate
z = Z > 0 for t ≤ 0 is determined using a fully relativistic multi-stream plane model
(encompassing the Lorentz-Maxwell equations) that is valid as long as the pulse depletion
can be negleted; up to WB, its equations reduce to a family (parametrized by Z) of decoupled
pairs of Hamilton equations for a 1-dimensional system where ξ = ct−z replaces
time t as the independent variable. We apply the procedure to a Gaussian laser pulse with
lfwhm = 10.5λ and a0 = 2; using the latter and two associated fn0(Z) as inputs, we then
determine the detailed plasma dynamics by FB-PIC simulations, confirming the predicted
maximal acceleration in the early LWFA stages.
Main references
[1] G. Fiore, P. Tomassini An analytical optimization of plasma density profiles for downramp
injection in laser wake-field acceleration, arXiv:2506.06814, to appear in Physica
D.
[2] G. Fiore, A preliminary analysis for efficient laser wakefield acceleration, 2022 IEEE
Advanced Accelerator Concepts Workshop (AAC), Long Island, NY, USA, 2022, pp.
1-6. https://doi.org/10.1109/AAC55212.2022.10822960.
[3] G. Fiore, T. Akhter, S. De Nicola, R. Fedele, D. Jovanovi´c, On the impact of short
laser pulses on cold diluted plasmas, Phys. D: Nonlinear Phenom., 454 (2023), 133878.
[4] G. Fiore, M. De Angelis, R. Fedele, G. Guerriero, D. Jovanovi´c, Hydrodynamic impacts
of short laser pulses on plasmas, Mathematics 10 (2022), 2622.
[5] G. Fiore, Travelling waves and a fruitful ‘time’ reparametrization in relativistic electrodynamics,
J. Phys. A: Math. Theor. 51, 085203 (2018).
