Energetic-Particle Populations and Cosmic-Ray Entry

Abstract

This paper constitutes a review of recent progress in the study of chargedparticle access, transport, and loss with respect to the earth's magnetosphere. A major objective of studying particle access is to identify the sources of trapped and quasi-trapped radiation. Important progress in this area involves the measurement of comparative ionic abundances in the radiation belts. The historic problem of accounting for cosmic-ray cut-off latitudes as a function of particle energy is being solved by the adoption of increasingly realistic and accurate models of the magnetospheric B field. Progress in the estimation of particle-transport coefficients (mainly diffusion coefficients) involves the measurement of fluctuating electric and magnetic fields on the ground, at balloon altitudes, and in space. The importance of particle interactions with discrete waveforms (as distinguished from broad-banded spectral noise) is increasingly being recognized. For example, the unsteady magnetospheric convection associated with substorms contributes importantly to radial diffusion, whereas cyclotron resonance with chorus elements and other discrete excitations may contribute importantly to pitch-angle diffusion and (thus) to the loss of energetic particles from the magnetosphere. The role of man-made signals such as radio transmissions and power-line harmonics in this latter process remains uncertain and continues to be debated.

Earth's radiation belts

“…The number of references has been held down in order to emphasize general principles and to provide coverage in depth on selected topics. Recent and more exhaustive reviews on ion composition [Cornwall and Schulz, 1979] and on energetic particle populations [Schulz, 1980] may provide additional references relevant to various general and special topics.…”

“…Rather than recount in full the accomplishments of radiation belt science for the 1976-1979 time period, the author directs attention to a recently published review [Schulz, 1980] of radiation belt papers from the 1977-1979 period and provides in this section a synopsis of selected highlights from that review, together with some background material to provide a historical framework and perspective. Subsequent sections provide a look into the future.…”

“…The selection of topics is not meant to be exhaustive by any means. The recent review by Schulz [1980] cites about 80 references in context and more than 400 in a supplementary bibliography, and this was supposed to cover only a 2-year period (roughly September 1977 to November 1979). A thorough treatment of the entire IMS data acquisition phase (1976-1979) would not be feasible in the space available here, but a feeling for the flavor of IMS research on radiation belt science nevertheless emerges.…”

Earth's Radiation Belts.

“…The number of references has been held down by the decision to emphasize broad principles over special topics. Recent reviews of a more exhaustive character on ion composition [Cornwall and Schulz, 1979] and energetic-particle populations [Schulz, 1980], however, have provided extensive reference lists e relevant to the various general and special topics.…”