Efficient production of a collimated MeV proton beam from a Polyimide target driven by an intense femtosecond laser pulse

Nishiuchi, Mamiko; Daido, Hiroyuki; Yogo, Akifumi; Orimo, Satoshi; Ogura, Koichi; Ma, J.-L.; Sagisaka, Akito; Mori, Michiaki; Pirozhkov, A. S.; Kiriyama, Hiromitsu; Bulanov, S. V.; Esirkepov, T. Z.; Choi, I. W.*; Kim, C. M.*; Jeong, T. M.*; Yu, T. J.*; Sung, J. H.*; Lee, S. K.*; Hafz, N.*; Pae, K. H.*; Noh, Y.-C.*; Ko, D.-K.*; Lee, J.*; Oishi, Yuji*; Nemoto, Koshichi*; Nagatomo, Hideo*; Nagai, Keiji*; Azuma, Hirozumi*

High-flux energetic protons whose maximum energies are up to 4 MeV are generated by an intense femtosecond Titanium Sapphire laser pulse interacting with a 7.5, 12.5, and 25m thick Polyimide tape targets. The laser pulse energy is 1.7 J, duration is 34 fs, and intensity is 310Wcm. The amplified spontaneous emission (ASE) has the intensity contrast ratio of 410. The conversion efficiency from laser energy into proton kinetic energies of 3% is achieved, which is comparable or even higher than those achieved in the previous works with nanometer-thick targets and the ultrahigh contrast laser pulses (10).