Secure Identifications of the Electron Diffusion Region with Spacecraft Observations

Details Secure Identifications of the Electron Diffusion Region with Spacecraft Observations Secure Identifications of the Electron Diffusion Region with Spacecraft Observations

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsm23d..03s&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #SM23D-03

Physics

[2109] Interplanetary Physics / Discontinuities, [2723] Magnetospheric Physics / Magnetic Reconnection, [2724] Magnetospheric Physics / Magnetopause And Boundary Layers, [2753] Magnetospheric Physics / Numerical Modeling

Scientific paper

The Electron Diffusion Region (EDR) plays a key role in the reconnection process and its detection in spacecraft data is one of the major goals of MMS. However, the observable and diagnostic properties of entry into the EDR of collisionless magnetic reconnection remain a matter of much debate. There are also even some theoretical disagreements as to how to define secondary and tertiary properties of the EDR, that may be the only properties that are practically observable. Here we start with first principles of what the EDR is in a general magnetic topology including anti-parallel and guide field regimes. We motivate the EDR as the site in the reconnection layer where magnetic flux is not preserved for the comoving electron observer. Observable diagnostics were then found based on kinetic theory that (i) can be measured in the data, and (ii) that also highlight the theoretically motivated EDR found in the PIC simulations. We compare and contrast our diagnostics with those used by others. We present results from PIC simulations of an RD, an EDR layer, and a fast shock to illustrate their degeneracy under evidence presented in the literature to support EDR “sightings”. Seven (7) properties are shared by these layers. Invariably one of these seven inspecific tests are invoked in the literature when “EDR’s” are identified. A particularly common inspecific test is any and all violations of the Ideal Electron MHD (IEMHD) condition: E+UexB=0, whether from parallel E field detection or perpendicular deviations from IEMHD=0. PIC simulations clearly show that all three current layers possess violations of the ideal electron MHD condition; this result implies that the common usage of violations of IEMHD=0 to define, identify or corroborate a current layer as the EDR are not theoretically appropriate. Our kinetic, observable diagnostics however do differentiate amongst this degenerate class of propagating current layers. For example, these observables clearly differentiate a freely propagating RD - Alfven wave from an EDR layer, although both degenerately would satisfy the Walen test performed with electron flow and magnetic variables. We also show that the first principles definition of the EDR only selects the EDR layers from amongst this degenerate set of current layers.

Affiliated with

Also associated with

No associations

Rating

Secure Identifications of the Electron Diffusion Region with Spacecraft Observations 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 Secure Identifications of the Electron Diffusion Region with Spacecraft Observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Secure Identifications of the Electron Diffusion Region with Spacecraft Observations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1878184