AMPLIFIED ELECTROSTATIC TRANSVERSE-WAVES IN PULSAR MAGNETOSPHERES

The natural modes of a relativistic, dense pair plasma streaming along field lines consist of electrostatic transverse waves (the subluminal branch of the ordinary mode) and purely transverse waves (the extraor dinary mode). In the case of a strong, uniform magnetic field, the bea m-plasma instability can occur only for longitudinal waves propagating along the field lines. It is shown that, when curvature drift is incl uded, a beam-plasma instability of the 'hydrodynamic' type can occur f or electrostatic transverse waves. Possible applications to pulsar rad io emission are discussed. It is shown that the instability for longit udinal waves propagating along the field lines can be suppressed by cu rvature drift when the Lorentz factor of the beam particles is large. This upper limit on the Lorentz factor for instability to occur is der ived.