Description
G. Cristoforetti, F. Baffigi, F. Brandi, G. D’Arrigo, A. Fazzi, L. Fulgentini, D. Giove, P. Koester, L. Labate, G. Maero, D. Palla, M Romé, R. Russo, D. Terzani, P. Tomassini and L.A. Gizzi
Plasma Phys. Control. Fusion 62 (2020) 114001
Abstract
In this paper we report the measurement of laser-driven proton acceleration obtained by
irradiating nanotube array targets with ultrashort laser pulses at an intensity in excess of 1020 W cm−2. The energetic spectra of forward accelerated protons show a larger flux and a higher
proton cutoff energy if compared to flat foils of comparable thickness. Particle-In-Cell 2D
simulations reveal that packed nanotube targets favour a better laser-plasma coupling and
produce an efficient generation of fast electrons moving through the target. Due to their
sub-wavelength size, the propagation of e.m. field into the tubes is made possible by the
excitation of Surface Plasmon Polaritons, travelling down to the end of the target and assuring a
continuous electron acceleration. The higher amount and energy of these electrons result in turn
in a stronger electric sheath field on the rear surface of the target and in a more efficient
acceleration of the protons via the target normal sheath acceleration mechanism.
