Electron cooling of positrons

This article deals with the relaxation of a positron beam in electron gas moving in a magnetic field. A situation is considered where the electron longitudinal temperature is lower than the transverse one. Expressions for the friction force and scattering coefficients of positron momenta have been found, with plasma shielding taken into account. In a strong magnetic field the effective cross section of the cooling process of the longitudinal motion of positrons is shown to be determined by their longitudinal velocity relative to the electron gas. The similarity of frequencies of Larmor rotation of electrons and positrons sharply increases in its turn the cooling intensity of the transverse degree of freedom of positrons. These circumstances can be used for multiple acceleration of high-temperature positron beam cooling. (orig.)