Improvement in the heating efficiency of fast ignition inertial confinement fusion through suppression of the preformed plasma. (25th April 2017)

• Record Type: Journal Article
• Authors: Arikawa, Y.; Kojima, S.; Morace, A.; Hata, M.; Sakata, S.; Fujioka, S.; Kawashima, T.; Hironaka, Y.; Shigemori, K.; Abe, Y.; Zhang, Z.; Vaisseau, X.; Lee, S.; Gawa, T.; Matsuo, K.; Law, K.F.F.; Kato, Y.; Matsubara, S.; Tosaki, S.; Yogo, A.; Nagatomo, H.; Tokita, S.; Nakata, Y.; Jitsuno, T.; Miyanaga, N.; Kawanaka, J.; Fujimoto, Y.; Yamanoi, K.; Norimatsu, T.; Nakai, M.; Nishimura, H.; Shiraga, H.; Azechi, H.; Sunahara, A.; Johzaki, T.; Ozaki, T.; Sakagami, H.;
• Other Names: collab.; collab.
• Is Part Of: Nuclear fusion. Volume 57:Number 6(2017:Jun.)
• Publication Date: 2017-04-25
• Subjects: fast ignition inertial confinement fusion -- electron acceleration by ultra intense laser -- laser–plasma interaction; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/aa6781
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: The study of fast electron spectrum optimization by suppression of preformed plasma in fast ignition targets is presented in this work. Integrated fast-electron spectra for electron energies below 3 MeV—the energy range responsible for core heating—are compared for different preformed plasma conditions. The pulse contrast (the ratio of peak-to-pedestal laser intensities) is compared for 10 8, 10 9 and 10 11 conditions at constant laser energy (~500 J), pulse duration (2 ps), spot size (30% encircled energy on 50 µ m diameter) and laser intensity (around 1 × 10 19 W cm −2 ). The best electron spectrum optimization, consisting of maximized electron number for energies below 3 MeV was obtained with 14 µ m thick cone targets. The energy coupling efficiency from heating laser to core plasma, assuming typical core plasma parameters, was estimated to be 2%, although 0.37% was obtained with previous conditions with poor pulse contrast and a 7 µ m thick cone target.