  Within the trln-formalism we investigate the vacuum interaction of cosmic
strings and the influence of strings width on this effect. For the massless
real scalar field we compute the Casimir contribution into the total vacuum
energy. The dimensional-regularization technique is used. It is shown that the
regularized Casimir term contains neither the UV-divergences, nor the
divergences related with the non-integrability of the renormalized vacuum mean
of the energy-momentum tensor.
