Speaker
Prof.
Yoshitaka Mori
(The Graduate School for the Creation of New Photonics Industries)
Description
A laser-driven inertial fusion energy (IFE) reactor should achieve the fusion of injected fuel pellets, which are continuously delivered into the reaction chamber and engaged by laser beams at 10’s Hz. Using a repetitive, 100-fs ultra-intense laser HAMA[1], we have demonstrated the engagement of 1-Hz-injected flying pellets involving fusion neutron reaction for the first time[2]. To induce the fusion burn, injected fuel pellets should be imploded to reach a high-density states that beyond 1000 times of solid density and an ignition temperature beyond 5 keV. A spherical shell is most reliable target design to achieve such a high-density state which has been confirmed in several inertial confinement fusion (ICF) facilities.
We have developed a testbed of shell injection system that delivers a spherical shell of deuterated polystyrene with 500 μm in diameter and 7 μm in thickness. The testbed was placed in a vacuum chamber with pressure below 0.02 MPa. 25 shells are lined up in a horizontal tube and pushed by the horizontal needle to the injection point. The vertical needle dropping speed, which is driven by the free-fall gravity, was carefully tuned not to destroy the shell being stuck each other due to static electricity. We found that shells were distorted by a force of the horizontal needle. When the number of shells exceeded 25, they started to be distorted by the needle force and then lost sphericity to the level less than 88%. The friction of the tube surface is the key of the system. The number of injected shells was also depending on the tip structure of the vertical tube. In the current system, the “cone dip” structure with line contact to the surface of the shell has in the best result for release and injection of the shells resulting injection-success-ratio of 75%.
We demonstrate that (i) repetitive shell injection was possible with the needle speed of 28 cm/sec to release the shell one by one without distortion of the shell structures, and (ii) distribution of injected shell after 18 cm free-fall was within 11 mm diameter circle, which is still 10 times larger than that of the bead injection system, and the laser-hit-ratio would be the level of 5%. This specification is enough for the first laser engagement experiment.
[1] Y. Mori et al., Nucl. Fusion 53 (2013) 073011.
[2] O. Komeda et al., Sci. Reports 3 (2013) 0730113.
| Country or International Organization | Japan |
|---|---|
| Paper Number | IFE/P4-6 |
Primary author
Prof.
Yoshitaka Mori
(The Graduate School for the Creation of New Photonics Industries)
Co-authors
Dr
Akifumi Iwamoto
(National Institute for Fusion Science)
Dr
Atsushi Sunahara
(Perdue Univ.)
Dr
Eisuke Miura
(National Institute of Advanced Industrial Science and Technology)
Prof.
Hitoshi Sakagami
(National Institute for Fusion Science)
Prof.
Katsuhiro Ishii
(The Graduate School for the Creation of New Photonics Industries)
Dr
Osamu Komeda
(Advanced Material Engineering Div., TOYOTA Motor Corporation)
Prof.
Ryohei Hanayama
(The Graduate School for the Creation of New Photonics Industries)
Prof.
Shinichiro Okihara
(The Graduate School for the Creation of New Photonics Industries)
Dr
Tatsumi Hioki
(Institutes of Innovation for Future Society, Nagoya Univ.)
Prof.
Tomoyoshi Motohiro
(Institutes of Innovation for Future Society, Nagoya Univ.)
Prof.
Tomoyuki Johzaki
(Hiroshima Univ.)
Dr
Yasuhiko NISHIMURA
(Toyota Technical Development Corp.)
Prof.
Yasuhiko Sentoku
(Institute of Laser Engineering, Osaka Univ.)
Prof.
Yoneyoshi Kitagawa
(The Graduate School for the Creation of New Photonics Industries)
