  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.
