HR: 1340h
AN: SM53B-0429    [Abstracts]
TI: An Electromagnetic Drift Instability In the Lower Hybrid Frequency Range In Reconnection Region
AU: * Ji, H
EM: hji@pppl.gov
AF: Princeton Plasma Physics Laboratory, Princeton University, PO Box 451, Princeton, NJ 08543
AU: Kulsrud, R
AF: Princeton Plasma Physics Laboratory, Princeton University, PO Box 451, Princeton, NJ 08543
AU: Fox, W
AF: Princeton Plasma Physics Laboratory, Princeton University, PO Box 451, Princeton, NJ 08543
AU: Yamada, M
AF: Princeton Plasma Physics Laboratory, Princeton University, PO Box 451, Princeton, NJ 08543
AB: By using a local two-fluid theory, we investigate an electromagnetic instability in the lower hybrid frequency range driven by cross-field current or relative drifts between electrons and ions. The theory self-consistently takes into account local cross-field current and accompanying pressure gradients. It is found that the instability is caused by reactive coupling between backward propagating whistler (fast) waves and forward propagating sound (slow) waves when the relative drifts are large. The unstable waves have mixed polarization with significant electromagnetic components, propagating obliquely to the unperturbed magnetic field. A physical picture of the instability emerges as a result of further simplifications of the model. The primary feedback mechanism is based on reinforcement of initial electron density perturbations by induced Lorentz force due to both field line bending and (de)compression. The resultant waves are qualitatively consistent with the measured electromagnetic fluctuations in reconnecting current sheet in a laboratory plasma. Detailed wave characteristics are also similar to measurements at reconnection sites of the magnetosphere. This work is supported by DOE, NASA, and NSF.
DE: 7831 Laboratory studies
DE: 7835 Magnetic reconnection
DE: 7867 Wave/particle interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting