Concerning the electromagnetic instability of a homogeneous anisotropic plasma

A study is made of the electromagnetic instability of a homogeneous plasma with a highly anisotropic one-or two-dimensional velocity distribution in the absence of a magnetic field. It is shown that, if the velocity distribution has a center of symmetry, then the plasma is always unstable against sufficiently long electromagnetic waves. This instability plays an important role in both laboratory plasma devices and cosmic rays.