Nonlinear dynamics of an ordinary electromagnetic mode in a pair plasma

Nonlinear generation of an ordinary electromagnetic mode (o mode), which ha s high phase velocity (upsilon(ph)much greater than c), and at the same tim e, is almost longitudinal for long wavelengths, is discussed in an electron -positron plasma. The solution of the problem of increasing energy ("plasmo n condensate") of the long-wavelength o mode based on modulations of the wa ve by the beat wave of two higher frequency transverse electromagnetic wave s (propagating along the external magnetic field) is proposed. The system o f equations describing three-dimensional nonlinear dynamics of this "superl uminal" o mode is derived and analytical solution for the modulated wave is found. The generated waves can have components propagating obliquely to th e magnetic field. Important consequences of the effect to processes in puls ar's magnetospheres, in particular, the pulsar radio emission, are discusse d.