Enhancement of nuclear reaction rates in asymmetric binary ionic mixtures

Abstract

Using orbital‐free molecular dynamics simulations we study the structure and dynamics of increasingly asymmetric mixtures such as hydrogen–carbon, hydrogen–aluminium, hydrogen–copper, and hydrogen–silver. We show that, whereas the heavy component structure is close to an effective one‐component plasma (OCP), the light component appears more structured than the corresponding OCP. This effect is related to the crossover towards a Lorentz‐type diffusion triggered by strongly coupled, highly charged heavy ions, and witnessed by the change of temperature scaling laws of diffusion. This over‐correlation translates into an enhancement of nuclear reaction rates much higher than its classical OCP counterpart.

Enhancement factor of nuclear reactions in partially ionized plasmas and asymmetric mixtures

“…The eBIM concept extends the already proposed model of effective OCP and should find further applications in the description of WDM mixtures, such as equations of state and ionic transport coefficients . This approach can also be extended straightforwardly to mixtures of more than two components.…”

“…The enhancement exponent H 0 was obtained by fitting its small‐ r behaviour with Widom's expansion in power of r 2 . We previously used this expansion to get an estimation of H 0 from a best fit of simulation data, assuming that hydrogen is completely ionized and that the two‐body interaction between hydrogen nuclei is coulombic. However, in OFMD simulations, the functional form of V ij ( r ) is a priori unknown.…”

Checking the Salpeter enhancement of nuclear reactions at intermediate coupling in asymmetric mixtures

“…The effect of the addition of a high Z element has been quantified in both regimes: The plasma enhancement is far higher in the weak coupling regime, and can scale H 0 /kT by almost one order of magnitude. The eBIM concept should find further applications in the description of WDM mixtures, such as equation of state and ionic transport coefficients [40,[42][43][44]. More com-plex mixtures (ternary etc.)…”

The advent of ab initio simulations of dense plasmas

“…[73] OFMD simulations also allowed to compute the properties of plasma mixtures in the 50-2000 eV range. Very asymmetric mixtures such as hydrogen mixed with silver are particularly interesting for the transport properties [74][75][76] and for the enhancement of nuclear reaction rates [77] presented at SCCS Kiel (2017) and in PNP-16, Saint-Malo (2018). [78]…”