Pressure driven currents derived from global ENA images by IMAGE/HENA

E. C. Roelof, P. C. Brandt, R. Demajistre, D. G. Mitchell, and B. Anderson

The Johns Hopkins University Applied Physics Laboratory, MD
(edmond.roelof@jhuapl.edu/fax: +1-240-228-0386)

The global ion distributions inverted from ENA images measured by IMAGE/HENA
can be used to calculate the plasma pressure. In principle, knowing the 
plasma pressure distribution and the magnetic field, one can also calculate 
the three-dimensional current system that is driven by the pressure gradient. 
The currents perpendicular to the magnetic field depend on the pressure 
gradient and the magnetic field strength.  Assuming current continuity 
(delta J = 0), the parallell currents are driven by the misalignment between 
delta B and pressure gradient.  We will describe a method where we use Euler 
potentials to calculate the current distribution. We will look at how the 
current depends on the choice of magnetic field model. The method will then 
be applied to some pressure distributions measured by IMAGE/HENA and the 
resulting field aligned currents (FAC) will be compared to the global FAC 
maps derived from Irridium magnetometer data.

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Presented at the 34th COSPAR Scientific Assembly, Houston, Texas, U.S.A.  
10-19 October 2002