The effect of Joule dissipation on field line resonance

Abstract Damped hydromagnetic eigenmodes are calculated numerically for a simple inhomogeneous plasma that is assumed to be contained within rigid perfectly conducting walls, and subject only to Joule dissipation. It is found that E ∥ must be included in order to obtain well-behaved damped eigenmodes that include resonant field lines, even though E ∥ is relatively very small. The thickness of the resonant region in the equatiorial plane, estimated from the model, is of order 10 −3 of an L number, which seems about two orders of magnitude too small to match observed long period micropulsations. The fact that mid-latitude micropulsations sometimes lead in phase at the lower latitudes is shown probably to be an effect of the local increase in resonant period with latitude.