Generation of energetic ions with non-Maxwellian energy distribution from a double-layer target irradiated by an ultra-intense laser pulse

• Published in: Journal of the Korean Physical Society 2022, 81(5), , pp.391-396
• Main Authors: Kim, Ha-Na, Lee, Kitae, Kumar, Manoj, Ryu, Woo-Je, Le, Cuong Nhat, Jeong, Young Uk, Kim, Kyung Nam, Park, Seong Hee, Jeon, Min Yong, Choi, Il Woo, Lee, Seong Geun, Kang, Seung Woo, Lee, Sang Hwa, Jeon, Cheonha, Jang, Yong Ha, Lee, Hwang Woon, Yoon, Jin Woo, Sung, Jae Hee, Lee, Seong Ku, Nam, Chang Hee
• Format: Article
• Language: English
• Subjects: Electric fields; Energy; Energy distribution; Energy spectra; Ion beams; Lasers; Mathematical and Computational Physics; Metal foils; Original Paper - Fluids; Particle and Nuclear Physics; Physics; Physics and Astronomy; Plasma and Phenomenology; Polymers; Proton energy; Theoretical; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.1007/s40042-022-00535-6

Carbon ions and protons from a double-layer target, a copper foil coated with a polymer exhibit non-Maxwellian spectral shapes, when an ultra-intense laser pulse with a high temporal contrast ratio was focused on the metal side of the target. The spectral shapes, showing strong reduction of low-energy ions, a high-energy island, and a modulated structure, are different from a typical thermal distribution usually obtained from a pure metal target in the laser acceleration of ions. In the case of C 6 + ion, a high-energy island with an energy spread of 0.5 MeV/u was observed, which is separated from the low-energy spectrum by 0.2 MeV/u. A modulation in the proton energy spectrum was observed, which leads to a secondary peak at 2.2 MeV/u in addition to a peak at a low energy of 1.5 MeV/u. The maximum energy obtained from the double-layer target at a laser intensity of 3 × 10 20 W/cm 2 is 3.4 MeV/u for C 6 + ions and 10 MeV/u for protons, which are higher than those obtained from a single metal foil by factors of 1.7 and 1.3, respectively. Such a spectral shape and energy enhancement could be accounted for by a bulk electrostatic field formed at the metal-polymer interface and multi-species interactions. These results show that the spectral shape of the ion beam can be tailored with an adequate structure of micrometer-thick target.