Radiation dominated implosion with nano-plasmonics

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 radiation.…”

“…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.…”

“…6. Csernai et al (2018) mention the possible advantages of the variable absorptivity, which is discussed in Chapter 4. Chapter 5 is the one dealing with the absorption increase using nanospheres, in which several papers are cited about the nanospheres increasing the absorptivity for visible radiation in cold matter.…”

Fusion hindrance effects in laser-induced non-neutral plasmas

“…The direction and importance of those variations critically depends on the reactants and plasma conditions, as can be seen by comparing equations (20), (40) and (42). In particular, it was found that primary (and beambeam) reactions are hindered by the analyzed environment, while secondary (and beam-target) 16 10 −6 fusions are moderately enhanced. Rate and average cross-section enhancement factors (ratios of screened to bare quantities) were explicitly computed for primary reactions between identical reactants.…”

“…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.…”