Nuclear probes of an out-of-equilibrium plasma at the highest compression

Abstract

We report the highest compression reached in laboratory plasmas using eight laser beams, E laser ≈12 kJ, τ laser =2 ns in third harmonic on a CD 2 target at the ShenGuang-II Upgrade (SGII-Up) facility in Shanghai, China. We estimate the deuterium density ρ D = 2.0 ± 0.9 kg/cm 3 , and the average kinetic energy of the plasma ions less than 1 keV. The highest reached areal density Λρ D =4.8 ± 1.5 g/cm 2 was obtained from the measured ratio of the sequential ternary fusion reactions (dd→t+p and t+d→α+n) and the two body reaction fusions (dd→ 3 He+n). At such high densities, sequential ternary and also quaternary nuclear reactions become important as well (i.e. n(14.1 MeV) + 12 C → n'+ 12 C* etc.) resulting in a shift of the neutron (and proton) kinetic energies from their birth values. The Down Scatter Ratio (DSR-quaternary nuclear reactions) method, i.e. the ratio of the 10-12MeV neutrons divided by the total number of 14.1MeV neutrons produced, confirms the high densities reported above. The estimated lifetime of the highly compressed plasma is 52 ± 9 ps, much smaller than the lasers pulse duration.

Radiation dominated implosion with nano-plasmonics

“…For simplicity of the presentation, we are neglecting the matter expansion, so that the target thickness h is taken to be constant. Experiment 6 indicates that this is an acceptable assumption.…”

“…Below, we suggest testing of the method with two laser beams pointing against each other with simultaneous irradiation pulses from both sides of the target. Such a configuration was tested recently successfully 6 , however without two fundamentally new aspects, the nearly simultaneous heating to ignition on a so called time-like hypersurface, with a final short energetic laser pulse and embedded nano-antennas in the target to modify light absorption to achieve nearly uniform heating in the whole target volume.…”

“…Linear laser irradiation will increase the density of transparent target, as pointed out in case of ultra-relativistic heavy ions 9 , and also indicated by ref. 6 . This mechanism is different from the ablator technique used in spherical geometry, and suppresses RT instability.…”

Fusion hindrance effects in laser-induced non-neutral plasmas

“…An inertial confinement fusion (ICF) plasma (see e.g. the introductory book [1] or papers as [12,13,14,15,16,17,18,19]) is obtained by irradiating a target, either solid or enclosed in an external shell, containing fuel for the purported fusion reaction, with several laser beams. Electrons in the target surface receive the photons energy and subsequently accelerate also ions.…”

“…Further assume for simplicity that the mean free path λ is the same for both reactants (which is always true using equation (17), and holds if and only if Z + = Z − using equation (15)). Then, the average of U |r 0 over x, carried out as in equation (16), is:…”