A spherical shell pellet injection system for repetitive laser engagement

Abstract

In laser-driven inertial fusion energy reactors, injected fuel pellets are continuously delivered into the reaction chamber and irradiated by laser beams injected at a frequency of tens of hertz. Thus far, a spherical shell pellet has been confirmed as the most conventional target design to achieve high-energy-density state thorough an implosion process that is required for fusion burn. To demonstrate repetitive fuel implosion with a 1 Hz joule-class laser system, a testbed of a shell injection system delivering a spherical shell (500 m diameter and 7 m thickness) was developed. The developed testbed demonstrated that (i) repetitive implosion (maximum frequency: 0.5 Hz) of shell injection was possible for more than ten shells at a shell speed of 191 mm s−1, and (ii) the distribution of the injected shell after 18 cm free-fall was within a circular region, 6.4 mm in diameter. The estimated laser-hit-ratio to the pellet was on the order of 10%.

Horizontal homing laser for high repetitive inertial fusion

“…This system was implemented at the Hamamatsu facility for a test of laser fusion (neutron generation) [10], and achieved a success rate of 22% [9]. The other uses needles to push spherical pellets to avoid electrostatic effects [11]. This system was operated at 10 Hz for 2 minutes with a position fluctuation of 1 mm (1σ) at the engagement point.…”

In-Line Target Production for Laser IFE

“…The target production area includes high-precision technologies for target fabrication, injection and tracking. These technologies are currently an important research stage in the leading laboratories of the world [9][10][11][12][13][14][15][16][17][18]. Target compression and ignition is regarded as a major challenge to the IFE community.…”