Laser polarization dependence of proton emission from a thin foil target irradiated by a 70 fs, intense laser pulse

Fukumi, Atsushi*; Takai, Mamiko; Daido, Hiroyuki; Li, Z.*; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Kado, Masataka; Hayashi, Yukio; Mori, Michiaki; Bulanov, S. V.; Esirkepov, T. Z.; Nemoto, Koshichi*; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Noda, Akira*; Nakamura, Shu

A study of proton emission from a 3-m thick Ta foil target irradiated by-, - and circularly polarized laser pulses with respect to the targetplane has been carried out. Protons with energies up to 880 keV were observed in the target normaldirection under the irradiation by the -polarized laser pulse, which yieldedthe highest efficiency for proton emission. In contrast, - and circularlypolarized laser pulses gave the maximum energies of 610 keV and 680 keV,respectively. The difference in the maximum energy between the - and-polarized cases was associated with the difference between thesheath fields estimated from electron spectra.