Coordinates for mapping the distribution of magnetically trapped particles

Abstract

Dipole representations of the earth's magnetic field have been found to have insufficient accuracy for the study of magnetically trapped particles. A coordinate system consisting of the magnitude of the magnetic field B and the integral invariant I has been found to organize adequately measurements made at different geographic locations. The present paper shows that a parameter L = ƒ(B,I) can be defined that retains most of the desirable properties of I and that has the additional property of organizing measurements along lines of force. Since the parameter L is the analog of a physical distance in a dipole field (the equatorial radius of a magnetic shell), it is usually found to present fewer conceptual difficulties than the integral invariant I.