The ducting of wave energy by field-aligned current sheets

A theoretical treatment of the modes of oscillation of an idealized current sheet (in which there is no perpendicular temperature) is given. For the simple case of a monoenergetic current sheet computational results are presented. These results indicate the existence of two types of ducted mode which may have relevance to observation. The first of these is a ducted “whistler” mode and the second occurs at somewhat higher frequencies and at phase velocities comparable with the streaming velocity of the current carriers in the sheet region. A simple explanation of how the ducted “whistler” mode can arise is given.