title: Direct heating of a laser-imploded core by ultraintense laser-driven ions.
abstract: A novel direct core heating fusion process is introduced, in which a preimploded core is predominantly heated by energetic ions driven by LFEX, an extremely energetic ultrashort pulse laser. Consequently, we have observed the D(d,n)^{3}He-reacted neutrons (DD beam-fusion neutrons) with the yield of 5×10^{8} n/4π sr. Examination of the beam-fusion neutrons verified that the ions directly collide with the core plasma. While the hot electrons heat the whole core volume, the energetic ions deposit their energies locally in the core, forming hot spots for fuel ignition. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with the yield of 6×10^{7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. A one-dimensional hydrocode STAR 1D explains the shell implosion dynamics including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions. A two-dimensional collisional particle-in-cell code predicts the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions, which could be an additional heating source when they reach the core. Since the core density is limited to 2 g/cm^{3} in the current experiment, neither hot electrons nor fast ions can efficiently deposit their energy and the neutron yield remains low. In future work, we will achieve the higher core density (>10 g/cm^{3}); then hot electrons could contribute more to the core heating via drag heating. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high gain fusion.
authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
authors.forename: Y
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authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
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authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
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authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
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authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
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authors.affiliation: The Graduate School for the Creation of New Photonics Industries, Kurematsucho, 1955-1 Nishi-ku, Hamamatsu 431-1202 Japan.
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authors.affiliation: Hamamatsu Photonics, K. K. Kurematsucho, 1820 Nishi-ku, Hamamatsu 431-1202, Japan.
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authors.lastname: Nishimura
authors.affiliation: Institute for Laser Technology, 1-8-4 Utsubo-honmachi, Nishi-ku, Osaka 550-0004, Japan.
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authors.lastname: Sunahara
authors.affiliation: Department of Physics, University of Nevada, Reno 1664 N Virginia Street, Reno, Nevada 89557, USA.
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authors.affiliation: TOYOTA Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute-cho, Aichi, Japan.
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authors.affiliation: TOYOTA Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute-cho, Aichi, Japan.
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authors.affiliation: TOYOTA Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute-cho, Aichi, Japan.
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authors.affiliation: National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
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authors.affiliation: Institute of laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565, Japan.
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authors.affiliation: Institute of laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565, Japan.
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authors.affiliation: Institute of laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565, Japan.
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authors.affiliation: National Institute for Fusion Science, 322-6 Oroshi Toki, Gifu 509-5292, Japan.
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