Theory and Hybrid Simulations of Transport due to Kinetic Alfven Waves at the Magnetopause

ROSES ID: NNH05ZDA001N      Selection Year: 2006      

Program Element: Focused Science Topic

Principal Investigator: Jay Johnson

Affiliation(s): Princeton University

Project Member(s):
Wing, Simon Collaborator The Johns Hopkins University
Lin, Yu Co-I Auburn University

Summary:

Recent observations have placed observational constraints on plasma

entry mechanisms for northward IMF conditions when the plasma sheet

cools and densifies. In particular, both in situ and remote

observations have found dawn-dusk asymmetries in the density and

temperature of the ion populations, and in situ particle distributions

show perpendicular ion heating of low energy ions on the dawnside

associated with strong compressional wave activity in the

magnetosheath. It is the purpose of this proposal to examine

transport processes that would occur due to kinetic and nonlinear

interactions associated with the large amplitude, low frequency waves

that are nearly always observed near the magnetopause in the context

of these observational constraints. We would address the following

scientific questions: (a) What is the nature of the low frequency wave

activity and how does it regulate plasma entry into the magnetosphere,

(b) What are the observational signatures expected from these

transport processes?, and (c) How do the observational signatures

compare with simulation and theory?





We will use a combined theoretical and computational approach to

understand how kinetic Alfven waves develop near the magnetopause and

contribute to transport. We will obtain wave solutions near the

magnetopause using the kinetic-fluid model (that include finite Larmor

radius effects and wave particle interactions) that we will use to

understand transport and heating at the magnetopause using methods of

nonlinear dynamics. We will compare these results with hybrid

simulations in a simplified slab geometry to understand the nonlinear

aspects of low-frequency MHD waves at the magnetopause. Using this

insight, we will perform and interpret three-dimensional hybrid

simulations in a realistic magnetospheric geometry. We will examine

the dependence of transport on solar wind conditions and the location

along the magnetopause where particle entry occurs. We will compare

our theoretical models with observations of wave activity, particle distributions,

and global asymmetries.





This project is directly relevant to the Living with a Star Targeted

Research and Technology program Focused Science Topic area (c) Solar

Wind Plasma Entry and Transport in the magnetosphere because we will

address the means by which plasma crosses the magnetopause and we will

quantify the amount of solar wind entering the magnetosphere due to

low frequency kinetic Alfven wave activity and

identify where it enters along the boundary. This proposal is also

relevant to NASA's national research objectives to explore the dynamic

earth system because we will have improved understanding of space

environmental conditions and their causes which will increase

capabilities for space flight and exploration.

Publications:

Performance Year	Reference	Investigation Type	Actions
1	Lin, Y.; Johnson, J. R.; Wang, X. Y.; (2010), HybridÂ...	not set

Presentations:

Performance Year	Reference	Actions
1	Johnson, J. R.; Lin, Y.; (2007), Signatures of Resonant ...
1	Lin, Y.; Johnson, J. R.; Wang, X.; (2007), Hybrid Sim...
1	Johnson, J. R.; Lin, Y.; Wing, S.; Kim, E.; (2008), ...
1	Johnson, J.; Otto, A.; Lin, Y.; Wing, S.; Kim, E.; ...
1	Lin, Y.; Johnson, J.; Wang, X.; (2009), Hybrid Simulat...

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