Two-stream Instability in Pulsar Magnetospheres

Creation of electron-positron pairs near the pulsar surface and the parameters of plasma in pulsar magnetospheres are discussed. It is argued that the pair creation process is nonstationary, and the pair plasma that flows out from the pulsar environment is strongly nonhomogeneous and gathers into separate clouds. Plasma instabilities in the outflowing plasma are reviewed. The two-stream instability that develops due to strong nonhomogeneity of the outflowing plasma is the most plausible reason for the generation of coherent radio emission of pulsars. The development of the two-stream instability in pulsar magnetospheres is considered