Radiative Damping Effect for Ultrarelativistic Channelled Particles

A theoretical consideration is given to a possibility of focusing ultrarelativistic positrons and electrons under channelling conditions. The decrease of the transverse energy is mainly due to energy losses by a specific radiation considered recently by Kumakhov. This effect appears for electrons at energies of several GeV and for positrons of several dozens of GeV. The mechanism perturbing focusing is multiple scattering. The focusing effect decreases the divergence of the beam penetrating through the target. Target thicknesses which are necessary to exhibit this effect are estimated.