Two-dimensional electron-magnetohydrodynamic instabilities

The linear dispersion relation and the spatial structure of high frequency instabilities, with a mixed tearing-bending character is studied. These ins tabilities are driven by the electron velocity gradient in a collisionless electron plasma moving against a background of immobile neutralizing ions i n an inhomogeneous magnetic field. As the angle between the perturbations a nd the magnetic field lines is varied, perturbations change from the tearin g type (parallel propagation) to the bending type (perpendicular propagatio n). (C) 1999 American Institute of Physics. [S1070-664X(99)01406-8].