THEORY OF TRANSVERSE-PLASMA STRUCTURES IN AN EXTERNAL ELECTRIC-FIELD

An anisotropic instability of a plasma in the presence of either a con stant electric field or an external microwave field is studied. This i nstability arises in the presence of nonzero directed electron velocit y and leads to the generation of a spatially periodic quasistatic magn etic held. A nonlinear time-dependent equation describing the instabil ity dynamics is derived, and the time-independent solution to this equ ation, which describes the final stage of the formation of a periodic current-sheet structure, is analyzed.