[Show abstract][Hide abstract] ABSTRACT: On January 8, 1996, the Geotail satellite skimmed along the dayside magnetopause from the dawnside to the duskside and observed a series of quasiperiodically recurring pulsed boundary layers in the prenoon (~0900-1000 LT) and the postnoon (~1400-1500 LT) sectors. For both intervals the interplanetary magnetic field observed by the Wind satellite upstream of the bow shock was inferred to be southward from an estimated convection time between Wind and Geotail. During the pulsed events, Geotail observed bipolar signatures in the magnetic field component normal to the nominal magnetopause. In the prenoon sector the bipolar variation had the inward-then-outward polarity, while in the postnoon sector the polarity was opposite (i.e., outward-then-inward). The plasma flows normal to the nominal magnetopause showed bipolar signatures with the inward-then-outward polarity in the prenoon and postnoon sectors. They were accompanied by sunward flows for the lower-density pulsed events and by tailward flows for the higher-density pulsed events. We have interpreted the sunward flow as the local plasma response to a tailward moving flux tube. This may imply that the sunward plasma flow near the magnetopause does not always reflect the direction of the motion of the flux tube. On the basis of these observations, we suggest that the observed pulsed boundary layers are attributed to the passage of a train of flux transfer events propagating tailward.
No preview · Article · Feb 2001 · Journal of Geophysical Research Atmospheres
[Show abstract][Hide abstract] ABSTRACT: An X-ray scattering study is presented of the orientational phase diagram of Si surfaces misoriented by up to 5.2° from the cubic  direction towards , and for temperatures between 300 and 1500 K. At the highest temperatures (above 1200 K), the surface is uniformly stepped. In this region, the intensity of near-specularly scattered X-rays increases with decreasing temperature, suggesting a corresponding increase in the surface roughness as a result of a direct attractive interaction between steps. For temperatures below a tricritical point of T′t = 1200 K, there occurs a two-phase region in which (113) facets appear in coexistence with stepped phase regions. For temperatures below a triple point at T′3 = 1180 K, coexistence between (113) facets and (55 12) facets is found. These results pertain to the sample heating current directed towards [332̄]. For heating currents directed in the opposite direction, there occurs an electric-field-induced instability, which has a significant effect on the high-temperature morphology.