Inertial confinement fusion (ICF) targets can be imploded by heavy-ion beams (HIBs) in order to obtain a highly compressed fuel microsphere. The hydrodynamic efficiency of the compression can be optimized by tuning the ablation process in order to produce the total evaporation of the pusher material by the end of the implosion. Such pusherless compressions produce very highly compressed targets for relatively short confinement times. However, these times are long enough for a fusion burst to take place, and burnup fractions of 30% and higher can be obtained if the volume ignition requirements are met. Numerical simulations demonstrate that targets of 1-mg DT driven by a few MJ can yield energy gains of over 70. Although direct drive is used in these simulations, the main conclusions about volume ignition are also applicable to indirect drive.
Keywords:Hybrid nuclear reactors Neutron multiplication Reactivity Tritium breeding Coolant selection After reviewing the long-standing tradition on hybrid research, an assessment model is presented in order to characterize the hybrid performance under different objectives. In hybrids, neutron multiplication in the subcritical blanket plays a major role, not only for energy production and nuclear breeding, but also for tritium breeding, which is fundamental requirement in fusion-fission hybrids. All three objectives are better achieved with high values of the neutron multiplication factor (/c-eff) with the obvious and fundamental limitation that it cannot reach criticality under any event, particularly, in the case of a loss of coolant accident. This limitation will be very important in the selection of the coolant. Some general considerations will be proposed, as guidelines for assessing the hybrid potential in a given scenario. Those guidelines point out that hybrids can be of great interest for the future of nuclear energy in a framework of Sustainable Development, because they can contribute to the efficient exploitation of nuclear fuels, with very high safety features. Additionally, a proposal is presented on a blanket specially suited for fusion-fission hybrids, although this reactor concept is still under review, and new work is needed for identifying the most suitable blanket composition, which can vary depending on the main objective of the hybrid.
The very clean nuclear fusion reaction of hydrogen and boron-11 by inertial confinement arrives at conditions for power stations by volume ignition only at compressions to 100,000 times the solid state. The earlier (numerically) observed anomaly of decreasing gain at increasing density (retrograde behavior) is analyzed and the reason clarified: the strong stopping power mechanism, based on Gabor's collective model, is reaching its limit of too small Debye lengths at the extremely high densities because of the optimum temperature in the range of 30 keV due to the reabsorption of the bremsstrahlung. The relativistic correction of the bremsstrahlung for the always much higher temperatures after volume ignition is included from Maxon's model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.