Observations of electron diffusion regions at the subsolar magnetopause

Electric and magnetic field observations on the Polar satellite at the subsolar magnetopause show that the magnetopause current is often striated. The largest of the resulting current channels are interpreted as electron diffusion regions because their widths are several electron skin depths and the electron flow U-e within them does not satisfy (E) over right arrow+(U) over right arrow (e)x (B) over right arrow =0. The data suggest that the magnetopause contains many such electron diffusion regions and that they are required because (E) over right arrowx (B) over right arrow /B-2 drifting electrons cannot carry the large filamentary currents imposed on the local plasma. The most probable interpretation of (E) over right arrow+(U) over right arrow (e)x (B) over right arrow not equal0 is that the pressure term on the right side of the generalized Ohm's law balances this inequality.