Paraxial approximation for the charge radiation in a magnetic field

The paraxial method for calculation of the relativistic charge radiation in a magnetic field is presented. The method is based on expanding the motion and radiation formulae for a small angle between the velocity vector and the trajectory axis. Some other conditions that allow us to apply the method are determined. The obtained expressions for the spectral and angular distribution of radiation do not contain the velocity or acceleration of charge: they are expressed through the vector potential on the trajectory axis.