Scalings of implosion experiments for high neutron yield

Abstract

A series of experiments focused on high neutron yield has been performed with the Gekko-XII green laser system [Nucl. Fusion 27, 19 (1987)]. Deuterium–tritium (DT) neutron yield of 1013 and pellet gain of 0.2% have been achieved. Based on the experimental data from more than 70 irradiations, the scaling laws of the neutron yield and the related physical quantities have been studied. Comparison of the experimental neutron yield with that obtained by using a one-dimensional fluid code has led to the conclusion that most of the neutrons produced in the stagnation phase of the computation are not observed in the experiment because of fuel–pusher mixing, possibly induced by the Rayleigh–Taylor instability. The coupling efficiency and ablation pressure have been calculated using the ion temperature measured experimentally. A coupling efficiency of 5.5% and an ablation pressure of 50 Mbar have been obtained.

Opacity Effect on Extreme Ultraviolet Radiation from Laser-Produced Tin Plasmas

“…The population of the ionization state was calculated under the collisional radiative equilibrium condition. Strong absorption is seen around 13.5 nm, arising mainly due to the 4p-4d and 4d-4f transitions of Sn 8 to Sn 13 . Several dips seen between 15 and 18 nm are due to the 4d-4f and 4d-5f transitions of Sn 4 to Sn 6 ions.…”

“…Radiation-hydrodynamic simulation (ILESTA-1D) [13] predicts an averaged temperature and density of the heated Sn sample of 30 eV and 0:01 g=cm 3 at 1 ns after the peak of the heating x-ray pulse. For measuring the expansion velocity of the heated sample, an x-ray shadowgraph of the sample was observed from the side with a temporal resolved x-ray backlighting technique until 1.0 ns after the peak of the heating x-ray pulse.…”

A pathway to laser fusion energy in Japan

“…The result appeared as a cover story of Nature. Furthermore, the University successfully achieved 1x10 13 neutrons with a fuel temperature of 100 million degrees required for nuclear fusion through optimization of the implosion mode [16]. The Lawrence Livermore National Laboratory recorded twice the number of neutrons with the same scheme but larger laser energy.…”

Conceptual design of fast-ignition laser fusion reactor FALCON-D

“…To examine the feasibility of such small yield, high gain target design, we performed implosion simulations by using 1-D hydrodynamics code ILESTA-1D [1]. Here we adopted a spherical-shell type cryogenic D-T fuel pellet surrounded by a plastic ablator layer.…”