Radiation-Dominated Implosion with Flat Target

Abstract

Inertial Confinement Fusion is a promising option to provide massive, clean, and affordable energy for humanity in the future. The present status of research and development is hindered by hydrodynamic instabilities occurring at the intense compression of the target fuel by energetic laser beams. A recent proposal by Csernai et al. 1 combines advances in two fields: detonations in relativistic fluid dynamics and radiative energy deposition by plasmonic nano-shells. The initial compression of the target pellet can be eliminated or decreased, not to reach instabilities. A final and more energetic, short laser pulse can achieve rapid volume ignition, which should be as short as the penetration time of the light across the target. In the present study, we discuss a flat fuel target irradiated from both sides simultaneously. Here we propose an ignition energy with smaller compression, largely increased entropy and temperature increase, and instead of external indirect heating and huge energy loss, a maximized internal heating in the target with the help of recent advances in nano-technology. The reflectivity of the target can be made negligible, and the absorptivity can be increased by one or two orders of magnitude by plasmonic nano-shells embedded in the target fuel. Thus, higher ignition temperature and radiation dominated dynamics can be achieved. Here most of the interior will reach the ignition temperature simultaneously based on the results of relativistic fluid dynamics. This makes the development of any kind of instability impossible, which up to now prevented the complete ignition of the target.

Inertial fusion without compression does not work either with or without nanoplasmonics

“…The recent paper of Csernai et al (2018) commented here is even more problematic in this respect. The authors carried out calculations for an uncompressed ball heated by external radi-ation.…”

“…According to these textbooks, the fusion efficiency (determined by the fusion cross-section and the thermal expansion) is given by a formula: w = ρR/(ρR + 6 g/cm 2 ). In case of a target of initially 1.062 g/cm 3 density with a radius of 640 μm -as proposed in the paper by Csernai et al (2018) -ρR ≈ 0.07 g/cm 2 which results in a burn fraction as low as ≈1%.…”

“…Thus, the visible radiation will not penetrate into the depth of the target, but it will be absorbed within the underdense plasma and the skin layer of the generated plasma. Csernai et al (2018) assume a constant opacity during the whole process, and they do not take into account the variation of opacity during the heating process and hot plasma formation. 5.…”

Comparative Study on the Uniform Energy Deposition Achievable via Optimized Plasmonic Nanoresonator Distributions

“…In our previous studies, we have proposed a novel approach to promote uniform energy deposition and to ensure time-like ignition of fusion targets by doping them with metal nanoparticles [29]. Energy deposition increased by plasmonic nanoparticles allows the initial compression of the fusion target to be reduced, thus avoiding Rayleigh-Taylor instability that prevents the achievement of inertial confinement fusion [30].…”

“…It has also been shown that time-like ignition can be achieved via double-sided irradiation with short and intense laser pulses even at reduced compression, when the absorption of a target is improved by orders of magnitude due to embedded plasmonic core-shell nanoparticles [29]. Beside the energy deposition the charge separation on nanoparticles is also an important aspect, since its amplitude might be commensurate with that accompanying the laser wake field (LWF) dense plasma waves initiated by two intense counter-propagating laser pulses [31].…”