Stationary Alfvén Waves


In collaboration with the University of Calgary and UCLA

Objective: To excite stationary inertial Alfvén waves in LAPD’s high-density plasma and compare properties of wave and particle dynamics to analytical theory and computer simulation

Significance: Stationary waves may play a role in low-frequency auroral-particle dynamics, particularly earthward electron precipitation. Presently, no model exists for the long-lifetime auroral structures routinely seen in space. Alfvén waves are accompanied by a parallel electric field that accelerates charged particles. Electron precipitation is a primary observational signature of aurora.

Long Range Goal: To explain the full frequency range of auroral behavior and its observational signatures.

Collaborators: Sean Finnegan, Mark Koepke, David Knudsen (Univ. Calgary)

This project involves a nonlinear, collisional, finite-temperature, two-fluid model of uniform plasma convection across B-field-aligned current sheets.

The theory is complemented by experiments that are being done at the Los Angeles Plasma Device (LAPD) at UCLA.

Dissipative effects of ion collisions are shown to alter the perpendicular ac and dc structure of parallel electron drift velocity. Electron collisions are shown to either increase or decrease the field-aligned electron energy, depending on the initial electron drift speed. Finite electron resistivity supports the wave field and causes the enhancement of field-aligned electron energy. Ion collisions either increase or decrease the field-aligned electron energy, depending on the initial electron drift speed.