Other
Scientific paper
Dec 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002agufmsm21c..04s&link_type=abstract
American Geophysical Union, Fall Meeting 2002, abstract #SM21C-04
Other
2463 Plasma Convection, 2712 Electric Fields (2411), 2724 Magnetopause, Cusp, And Boundary Layers, 2728 Magnetosheath
Scientific paper
The electric fields that occur in a plasma in the presence of pressure gradients have long been inventoried in laboratory plasmas, but only recently have these same effects been taken seriously in the experimental space science community. When these effects are present, the electric field can no longer be inferred from fluid velocities and the magnetic field, but there are substantial (and detectable mV/m class) corrections to the unipolar electric field associated with the pressure gradients of the electron part of the plasma. A pressure ridge is theoretically anticipated astride the separator which implies that there are pressure gradients there and, in general, parallel electric fields of this type. Pressure gradient electric fields, whether parallel or not to B, occur in other places as well; accordingly the detection of pressure gradients and parallel E are not, by themselves, sufficient to indicate reconnection. In this paper we illustrate the power of cross strapping the plasma, electric and magnetic field measurements to elucidate a new picture of the electrodynamics of the magnetopause and its associated boundary layers. Even depletion layers, long held to be the hallmark of a magnetopause that is locally ``closed'', will be illustrated with well developed pressure gradient and parallel electric fields. A particularly well resolved layer yields the following picture of the scale lengths involved in this layer. As pressure variations are perceived in the time domain, the comparisons of the electron flow and the electromagnetic field suggest waxing and waning gradients that may be inverted to determine the time sequence of spatial scales encountered. As the depletion layer is traversed, the spatial scales do on average decrease, but they do not collapse to the electron inertial scale before the magnetopause is traversed. This type of crossing will be contrasted with a magnetopause layer where the observer penetrates the separator and all the classically expected signatures of reconnection are observed, and the spatial scales of such a reconnecting layer has collapsed to and asymptoted to the limiting electron inertial length, thereby demagnetizing the electrons. Such comparisons give the impression that the sights of reconnection depend on the precised collapse of scales that the local boundary conditions require: if they are not short enough to demagnetize the thermal electrons reconnection does not occur; if it does it has been observed to occur.
Maynard Nc.
Mozer F.
Ober D.
Scudder Jack D.
No associations
LandOfFree
Ambipolar Electric Fields Parallel and Perpendicular to the Local Magnetic Field: Magnetopause and Depletion Layers does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Ambipolar Electric Fields Parallel and Perpendicular to the Local Magnetic Field: Magnetopause and Depletion Layers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ambipolar Electric Fields Parallel and Perpendicular to the Local Magnetic Field: Magnetopause and Depletion Layers will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1438386