  The damping of the axionic string motion due to the surrounding plasma is
estimated by a detailed calculation of the fermion scatter from a global string
and it is shown that the friction force on the string can be neglected before
the axionic domain wall formation in most cases, which is one of the important
necessary conditions for the scaling distribution of the strings. The energy
density of the axion produced by the collapse of the axionic domain walls is
also evaluated using the axionic string distribution, and it is found to be
larger or at least comparable to the axion density which originates from the
axionic strings.
