Since 18 of December 2019 conferences.iaea.org uses Nucleus credentials. Visit our help pages for information on how to Register and Sign-in using Nucleus.
10-15 May 2021
Virtual Event
Europe/Vienna timezone
The Conference will be held virtually from 10-15 May 2021

Progresses of inertial fusion energy program at GPI Hamamatsu toward mini-reactor CANDY

12 May 2021, 14:00
4h 45m
Virtual Event

Virtual Event

Regular Poster Inertial Fusion Energy P4 Posters 4

Speaker

Yoshitaka Mori (The Graduate School for the Creation of New Photonics Industries)

Description

A mini-reactor called CANDY that based on kJ-class diode-pumped solid-state laser (DPSSL) is proposed to perform feasibility studies of the power plant in fast ignition scheme fusion. In order to implement CANDY, we have adressed two issues. First is a repetitive operation of pellet injection and laser illumination, second is target physics related to inertial confinement fusion plasma. First is achieved using repetitive laser system, (i) succeeded in 10 Hz injection of CD beads longer than 2 minutes, which was demonstrated for the first time using inserter that works at the same frequency of laser toward the reactor. Second issue is achieved using a world-class ultra-intense laser LFEX at ILE, Osaka University, here we have demonstrated (ii) an efficient heating of a counter imploded core of a density of 2.8±0.3 g/cc with temperature upto 1 keV with efficiency evaluated to be 9±0.8%. These results are encouraging and gives hints on the fast ignition scheme as a candidate toward future compact reactor developments.

A laser-driven inertial fusion energy (IFE) reactor achieves the fusion of injected fuel pellets, which are continuously delivered into the reaction chamber and engaged by laser beams at 10’s Hz. The target physics developments are expected to obtain fusion gain and developments of pellet injection and engagement are indispensable to realize laser fusion reactor. The Graduate School for the Creation of New Photonics Industries (GPI) have conducted laser inertial fusion program since 2008 with corroboration with industries and academia. Our strategy is to demonstrate integrated repetitive operation that scalable for future laser fusion power plant. We proposed a mini-reactor CANDY (1) that utilizes a few kJ/10 Hz laser driver with ~100 W fusion power (figure 1.). Toward its development, three key issues are conducted; (1) Repetitive laser development (2, 3), (2) Target physics related on counter illuminating fast ignition scheme (4, 5) and (3) Pellet injection & engagement with fusion reactions (6-8). Figure 2 represents specifications of achieve values in Hamamatsu, designed values of laser fusion mini-Reactor CANDY (1) and inertial fusion Test Reactor LIFT (Phase-IIII) (9). Here we report the present status of R&D toward the CANDY.
Concept of laser fusion mini-Reactor CANDY. Key issues include (i) Repetitive Laser, (ii) Target physics related to counter illumination fast ignition scheme and (iii) Pellet injection & engagement.
Specifications of achieved values in Hamamatsu for inertial fusion energy, designed values of laser fusion mini-Reactor CANDY (1) and inertial fusion Test Reactor LIFT (Phase-IIII) (9).

Repetitive laser development
In the Hamamatsu area, several repetitive laser systems those utilizing DPSSL are under operation. The first high repetitive inertial confinement fusion experiment laser system called HAMA (2) is under operation since 2008. The HAMA consists of a Ti : sapphire laser pumped by a 10J/1-10 Hz DPSSL. The HAMA utilizes counter fuel assembling beam with pulse tailoring and counter heating beam since 2013. In 2018, Hamamatsu Photonics have issued a press release of a 100-Joule class DPSSL based facility “TERU” (Trek on fusion Energy Roadmap toward Ultimate SDGs). That is under operation at 50 J/0.5 Hz with potential upto 10 Hz (3). Toward the fabrication of kJ-class DPPSL required for the CANDY, repetitive laser research and developments are on-going in Hamamatsu.

Target physics related counter illuminating fast ignition scheme
We have demonstrated an efficient imploded core heating using a using a world-class ultra-intense laser LFEX at ILE, Osaka University by improving imploding laser beams from the previous experiments (4). Six green beams from GEKKO XII(GXII) laser (0.53 μm, 1.1 ns, 1.7 kJ) haveimploded a CD shell target to a density of 2.4 x solid density, that forms a 2.8±0.3 g/cc core. When two beams from LFEX laser (1.053 μm, 1.5 ps, 0.25 kJ) were axially illuminating to GXII symmetric axis, the bulk ion temperature increases beyond 1.0 keV from 0.6-0.7 keV evaluated using a multi-channel neutron spectrometer and the inferred heating efficiency was 9±0.8%. This result indicates that, as far as core density stays around a few g/cc, direct illuminating fast ignition scheme can expect a degree of core heating while the imploded core was surrounded by ablating corona plasma.

Pellet injection & engagement
We have demonstrated 10 Hz operatin of bead pellete injection and engagemnt. The injection machine is upgraded from the previous 1 Hz injection system by increasing number of holes on disk rotor from 20 to 200 (6-8). As the results, we have achieved 10 Hz pellet injection and laser engagement that last beyond 2 minutes. The repetition rate is now upgraded to 10 Hz, the same frequency with laser repetition. Figure 3 represents experiments history of hit ratio per second for bead pellet injection & engagement system. The hit ratio beyonds 40% resulting in 5 times incremental of laser hit ratio per second from the previous results which indicates the first demonstration that the pellet injection frequency equals to that of laser amplified frequency, an important step to increase fusion power in the future power plant.
Experiment history of hit ratio per second for bead pellet injection & engagement system.

In conclusion, toward the laser fusion mini-reactor CANDY, we have made advances both on (i) target phsyiscs that the imploded core with density 2.8±0.3 g/cc are heated upto 1keV with heating coupling efficiency 9±0.8% using the ultra-intense laser LFEX at ILE, Osaka University, and (ii) pellet injection & engagement demonstrating a 10 Hz beads injection and laser illumination beyond 2 minutes with hit ratio beyond 40%.

(1) Y. Kitagawa et al., J. Phys. Conf. ser. 688, 012049 (2016).
(2) Y. Mori et al., Nucl. Fusion vol. 53, 073011 (2013).
(3) T. Watari et al., Proceedings of IAEA FEC2018 conference, IFE/P4-10 (2018).
(4) Y. Kitagawa et al., Phys. Rev. Lett. vol. 114, 195002 (2015), Nucl. Fusion vol. 57, 076030 (2017).
(5) Y. Mori et al., Phys. Rev. Lett. vol. 117, 005001 (2016), ibid. vol. 57, 116031 (2017).
(6) O. Komeda et al., Sci. Reports vol. 3, 2561 (2013).
(7) Y. Mori et al., Fusion Sci. & Technol. vol. 75, 36 (2019).
(8) Y. Mori et al., Nucl. Fusion vol. 59, 096022 (2019).
(9) T. Norimatsu et al., Nucl. Fusion vol. 57, 116040 (2017).

Affiliation The Graduated School for the Creation of New Photonics Industries
Country or International Organization Japan

Primary authors

Yoshitaka Mori (The Graduate School for the Creation of New Photonics Industries) Katsuhiro Ishii (The Graduate School for the Creation of New Photonics Industries) Ryohei Hanayama (The Graduate School for the Creation of New Photonics Industries) Prof. shin-ichiro Okihara (The Graduate School for the Creation of New Photonics Industries) Yoneyoshi Kitagawa (The Graduate School for the Creation of New Photonics Industries) Dr Osamu Komeda (Toyota Motor Corporation) Dr Esuke MIura (AIST) Akifumi Iwamoto (National Institute for Fusion Science) Dr Tetsuo Ozaki (National Institute for Fusion Science) Prof. Hitoshi Sakagami (NIFS) Prof. Tomoyoshi Johzaki (Hiroshima Univ. Eng.) Yasuhiko Sentoku (Institute of Laser Engineering, Osaka University) Yasunobu Arikawa (Insituteof Laser Engineering Osaka University) Dr Yuki Abe (ILE, Osaka University) Dr Nozomi Nakajima (ILE. Osaka University) Dr Mirfayzi Reza (Institute of Laser Engineering) Dr Shohei Sakata (ILE, Osaka University) Dr Kazuki Matsuo (ILE, Osaka University) Shinsuke Fujioka (Institute of Laser Engineering, Osaka University)

Presentation Materials