A model of the gyrophase-averaged electron distribution in the Earth's foreshock consistent with boundary conditions at the bow shock and in the solar wind has been constructed according to the reversible guiding center characteristics and compared with ISEE electron and wave observations.

This model demonstrates (1) that the basic features and morphology of beams in the observed and reduced distributions F(v∥) are determined almost exclusively by the solar wind electrons mirrored at the shock's magnetic ramp and are relatively insensitive to the leakage from the magnetosheath, (2) that the wave particle modifications have been detected by contrasting the reversible model with the direct observations, (3) that the nonmonotonic reduced distributions F(v∥) are rarely the result of a nonmonotonic energy spectra but are rather the result of the transverse velocity space integration necessary to produce F(v∥) from the directly observed electron distribution function f(v), (4) that the time scale for beam resupply to F(v∥) from the dc spatial gradients of the self-consistent reversible distribution function can have a factor of 100 variation across the foreshock, being shortest within a few degrees of the magnetic tangent surface, (5) that the beams predicted by the model have strongly varying and correlated variations of mean energy, thermal spread, and number density with angular departure from the magnetic tangent with the coldest, most tenuous, and lowest mean energy beams suggested to be present deep behind the magnetic tangent (≂5¿--10¿) that the lowest-energy beams have low contrast to the background solar wind distribution and although difficult to detect have beam density and temperature parameters compatible with &ohgr;<&ohgr;pe growth of electrostatic waves, and (7) that the highest-energy, warmest, and most dense beams occur nearer to, but not at, the magnetic tangent surface, have strong contrast with the undisturbed solar wind F(v∥), and are replenished so rapidly that they can defeat wave particle dispersal at almost any reported wave level in the Earth's foreshock. ¿ American Geophysical Union 1990