Plasma Transport from The Solar Wind to the Magnetosphere

ROSES ID: NNH05ZDA001N      Selection Year: 2006      

Program Element: Focused Science Topic

Principal Investigator: John Lyon

Affiliation(s): Dartmouth College

Project Member(s):
Rogers, Barrett Co-I Dartmouth College

Summary:

The mechanism by which the solar wind plasma enters the

magnetosphere remains an important and to a large degree

unanswered question. A number of mechanisms have been

proposed for this process. For example, there is direct

entry along newly reconnected field lines, there is

diffusive entry (perhaps drift mediated) along the

magnetopause, there is impulsive penetration, to name a

few. What does seem clear is that the amount of plasma

within the magnetosphere is correlated with the density in

the solar wind. This question of plasma entry has been

called out in the current NRA as an important science

question of interest to the NASA Sun-Earth Connection

Program.



We will attempt to determine the processes by which entry,

energization and energy extraction take place through a

number simulation codes, used singly and in concert. The

simulation codes are: 1. A global MHD magnetospheric code

which has been used successfully to model many of the

aspects of magnetospheric structure and dynamics. This will

be the workhorse for this project. It can be used to track

fluid elements from, say, positions in the plasma sheet to

their origins in the solar wind. 2. A particle tracking

code that integrates the Lorentz orbits of particles within

the system. In conjunction with the fields from the global

MHD code, it can give ihe currentsnformation about the

actual trajectories of the particles making up the

collisionless plasma. 3. Two fluid and hybrid codes to model

the boundary layers (magnetopause) of the global system. One

of the deficiencies of the MHD codes is that the boundary

layers are both not resolved and deficient in physics. This

makes the results of tracing particle trajectories through

such layers problematic.



Our approach will be two-fold. On one track we will

use the global MHD model to set up idealized situations

where the plasma enetry can be studied using the full array

of tools listed above. Typically, then the MHD code would

provide a base time-dependent configuration of electric and

magnetic fields, as well as fluid flows. The results for

plasma entry for the fluid model will then be compared

against the results for the particle tracing. The kinetic

codes will be used in conjunction with the particle tracing

to develop ideas about the actual rates of particle

penetration and reflection and energy gain or loss through

the boundary layer.



In the second track, we will try to

validate the models by reference to actual data. This is

generally easier with the MHD models than with the other

simulations. Here we will rely on a combination of single

event studies and upon statistical studies.

Publications:

Performance Year	Reference	Investigation Type	Actions
1	Pulkkinen, T. I.; Goodrich, C. C.; Lyon, J. G.; (200...	not set

Presentations:

Performance Year	Reference	Actions
1	Damiano, P. A.; Lotko, W.; Wiltberger, M. J.; Lyon,Â...
1	Damiano, P. A.; Lotko, W.; Wiltberger, M. J.; Lyon,Â...
1	Damiano, P. A.; Lotko, W.; Brambles, O. J.; Wiltberg...

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