Some problems in the theory of transient self-focusing

A theory of transient self-focusing of a high-power laser pulse is developed for a homogeneous optically isotropic transparent solid dielectric. An allowance is made for electrostriction, thermoelastic stresses, and the temperature dependence of the permittivity. The parabolic approximation is used for the initial moments. The time dependence of the diameter of the laser beam is determined in the focal region for linear absorption of ~10^–2 cm^–1. It is shown that the velocity of the focus is ~10⁸ cm/sec, which is in satisfactory agreement with the experimental results.