Analysis of Plasma Wave Growth, Anomalous Resistivity, and Diffusion in the Dayside Magnetopause and Reconnection Region

University Of Iowa, Iowa City IA

Investigators

Abstract

The effectiveness of plasma waves in providing sufficient anomalous resistivity in the reconnection region of the dayside magnetospause is an important and as-yet unresolved question. Plasma wave observations of the magnetopause/magnetosheath by the plasma wave instrument on board the Polar spacecraft have shown the correspondence between different wave modes and probable reconnection sites. The plasma wave instrument (PWI) on board Polar has the unique capability of positively identifying waves using 3 axis electric and magnetic observations at unprecedented resolutions. A one-dimensional electrostatic Vlasov simulation code has been used to investigate the role of ion acoustic waves in providing the necessary anomalous resistivity along the magnetopause reconnection region. The results have shown that analytical estimates of weak quasilinear effects were incorrect. These studies make a strong case for further non-linear studies of diffusion coefficients in the magnetopause region. This project will use the unique capabilities of the PWI on board the Polar spacecraft along with newly developed analysis tools to more accurately classify and analyze waves in this region. Observed plasma distribution functions which include electron and ion beams will be modeled to determine the existence and growth rates of the observed waves. Linear calculations will provide a benchmark for subsequent non-linear Vlasov and particle-in-cell (hybrid) simulations. The PWI high resolution waveform data will be used to determine wave modes and propagation properties. A newly developed compressible MHD mode analysis will be used to distinguish fast and slow mode waves at low frequencies. Particular attention will be given to the role of waves in providing anomalous/diffusive resistivity along the magnetopause and in the reconnection region. Particle-in-cell (PIC) and hybrid codes will be used to study the non-linear diffusion of waves along the magnetopause, including lower hybrid (LH), whistler mode and low-frequency electromagnetic modes. The results will complement the previous non-linear studies of the reconnection region. This work will involve the significant efforts of an undergraduate research assistant in the space physics program at the University of Iowa, as well as three visiting scholars from the Czech Republic.