The interaction of laser pulses with thin grating targets, having a periodic groove at the irradiated surface, was experimentally investigated. Ultrahigh contrast (∼1012) pulses allowed us to demonstrate an enhanced laser-target coupling for the first time in the relativistic regime of ultrahigh intensity >1019 W/cm2. A maximum increase by a factor of 2.5 of the cutoff energy of protons produced by target normal sheath acceleration is observed with respect to plane targets, around the incidence angle expected for the resonant excitation of surface waves. A significant enhancement is also observed for small angles of incidence, out of resonance.
Schematic top view of the experimental setup. The Thomson parabola and the frosted glass screen were located along the target normal direction and the laser specular directions, respectively.
1CEA/IRAMIS/SPAM, F-91191 Gif-sur-Yvette, France
2Istituto Nazionale di Ottica, Consiglio Nazionale delle Ricerche, research unit “Adriano Gozzini,” 56124 Pisa, Italy
3Dipartimento di Energia, Politecnico di Milano, 20133 Milano, Italy
4LULI, Université Pierre et Marie Curie, Ecole Polytechnique, CNRS, CEA, 75252 Paris, France
5FNSPE, Czech Technical University in Prague, CR-11519 Prague, Czech Republic
6Institute of Physics of the ASCR, ELI-Beamlines project, Na Slovance 2, 18221 Prague, Czech Republic
7CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex, France
8CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex, France
9LULI, UMR7605, CNRS-CEA-Ecole Polytechnique-Paris 6, 91128 Palaiseau, France
10Dipartimento SBAI, Università di Roma “La Sapienza,” Via A. Scarpa 14, 00161 Roma, Italy
11Dipartimento di Fisica “Enrico Fermi,” Università di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa, Italy
Copyright © 2008-2014, Fyzikální ústav AV ČR, v. v. i.
