Effect of impurities on nuclear fusion

TL;DR

This paper investigates how impurities in plasma can enhance nuclear fusion rates by altering Coulomb interactions, potentially impacting energy production in fusion reactors.

Contribution

It introduces a quantum mechanical model showing impurities can significantly increase nuclear contact probabilities, with numerical estimates for various fusion reactions.

Findings

Impurities can virtually eliminate Coulomb repulsion effects.

Enhanced reaction rates due to impurity-assisted mechanisms.

Potential practical implications for fusion energy production.

Abstract

Modification of nuclear reactions due to impurities in plasma is investigated. The hindering effect of Coulomb repulsion between reacting particles, that is effective in direct reactions, can practically disappear if Coulomb interaction of the reacting particles with impurities embedded in plasma is taken into account. The change of the wavefunction of reacting particles in nuclear range due to their Coulomb interaction with impurity is determined using standard time independent perturbation calculation of quantum mechanics. The result can be interpreted as if a slow, quasi-free particle (e.g. a proton) were pushed by a heavy, assisting particle (impurity) of the surroundings and can get (virtually) such a great magnitude of momentum which significantly increases the nuclear contact probability density and also the probability of its capture by an other nucleus. As a sample reaction the process, called impurity assisted nuclear $% pd$ reaction is investigated and the rate and power densities produced by the reaction are numerically calculated. With the aid of astrophysical factors the rate and power densities of the impurity assisted $% d(d,n)_{2}^{3}He$, $d(d,p)t$, $d(t,n)_{2}^{4}He$, $_{2}^{3}He(d,p)_{2}^{4}He$% , $_{3}^{6}Li(p,\alpha )_{2}^{3}He$, $_{3}^{7}Li(p,\alpha )_{2}^{4}He$, $%_{4}^{9}Be(p,\alpha )_{3}^{6}Li$, $_{4}^{9}Be(p,d)_{4}^{8}Be$, $%_{4}^{9}Be(\alpha ,n)_{6}^{12}C$, $_{5}^{10}B(p,\alpha )_{4}^{7}Be$ and $%_{5}^{11}B(p,\alpha )_{4}^{8}Be$ reactions are also estimated. The affect of plasma-wall interaction on the process is also considered. A partial survey of impurity assisted nuclear reactions which may have practical importance in energy production is also presented.