U. of West Virginia

Prof. Mark Koepke, University of West Virginia

Members of the Space Physics group at PPPL, Drs. Jay Johnson and Peter Damiano,  are collaborating with Prof. Mark Koepke of West Virginia University (and his collaborator Prof. David Knudsen at the University of Calgary) on nonlinear time-stationary inertial Alfven waves that can develop where convective magnetospheric plasma flow intersects regions of magnetic-field-aligned electric current.  Such a wave is nonstationary, meaning its electric field pattern does not oscillate in time, but instead oscillates in space, permitting steady-state electric field regions that can accelerate electrons parallel to the background magnetic field. Steady-state electron acceleration can lead to discrete auroral arcs, in other words bands of light in the upper atmosphere caused by electron-impact excitation of high-altitude gases like oxygen and nitrogen that give off light as they de-excite.  Since steady convective flows are ubiquitous in the tail region of the Earth's magnetosphere and in the auroral regions of the Earth's ionosphere, these stationary waves have garnered much interest in possible application to the formation of long-lived auroral arcs (see picture below), but have yet to be studied in computer simulations. Peter Damiano and Jay Johnson, from PPPL, are working with Mark Koepke to model these waves under the predicted natural space conditions using a hybrid particle-fluid simluation model and to compare results with theoretical and laboratory studies of stationary waves being conducted by his group at West Virginia.

Photo of a long-lived auroral arc entitled, "A Starry Night in Iceland", courtesy of NASA.