Electron and ion acceleration by nonlinear waves near the Earth

Abstract

In section 1 the properties of the large amplitude waves (especially these of solitary waves, ‘solitons’) are considered. In a soliton of maximum amplitude the energy of electron transverse movement equals that of ion longitudinal movement and amounts to a half of magnetic energy; hence, such structures afford an efficient mechanism transferring solar wind ion kinetic energy to the electrons. Let us designate the magnetic field and the plasma density of the undisturbed plasma by Ho and no; then the maximum field amplitude in the soliton crest equals Ht = (M/m)1/2 Ho and the electron and ion energy We = Wi = (½) (Ho²/8πno) (M/m) exceeds by three orders of magnitude that of the undisturbed field. A physical picture of this acceleration process is that the rapid time variation of the magnetic field generates a transverse electric field accelerating primarily the electrons because of their small mass. The presence of nonlinear waves with their peculiar properties may explain from a common standpoint several important geophysical phenomena: the formation of the outer radiation belt, the ring current within the earth magnetosphere, the small‐scale structure of the transition region, ionization of the night ionosphere, the polar aurora, the acceleration of the solar cosmic rays in the sun chromosphere, and the formation of cometary tails of the first kind. Such an explanation of experimental data constitutes section 2 of the paper.

Magnetic measurements in the Earth’s magnetosphere and magnetosheath: Mariner 5

“…This noise is presumably generated at the shock front and, perhaps to some extent, within the magnetosheath. The Pioneer 1 signals were distinctly asymmetric wiih a rapid rise and slow decay suggestive of solitary waves [Ginzburg, 1967]; the use of a non-linear amplifier (AGC), however, tended to cloud the issue of pulse asymmetry. Subsequent magnetosheath measurements on Explorers 12 and 14 and IMP's 1, 2, and 3 did not reveal pulses with such large field amplitudes, but the Mariner 4 data contained pulses with a recurrence interval similar to those seen on Pioneer 1, although their amplitude was only -,10), (see Figure 14 Of several experimental limitations that have significant consequences for the appearance of the data, probably the most important is the rate at which the waveforms were sampled.…”