Theory of weak bipolar fields and electron holes with applications to space plasmas.

A theoretical model of weak electron phase-space holes is used to interpret bipolar field structures observed in space. In the limit ephi(max)/Te << 1 the potential of the structure has the unique form, phi(x) = phi(max)sech4(x/alpha), where phi(max) depends on the derivative of the trapped distribution at the separatrix, while alpha depends only on a screening integral over the untrapped distribution. Idealized trapped and passing electron distributions are inferred from the speed, amplitude, and shape of satellite waveform measurements of weak bipolar field structures.