THE PHYSICAL SIGNIFICANCE AND APPLICATION OF L, B$sub 0$ AND R$sub 0$ TO GEOMAGNETICALLY TRAPPED PARTICLES

Journal Article · Mon Jul 15 04:00:00 EDT 1963 · Journal of Geophysical Research (U.S.)

DOI:https://doi.org/10.1029/JZ068i014p04157· OSTI ID:4687845

Stone, E C

In a dipole field, many different invariant shells (I,B/sub m/) share exactly the same lines of force. These invariant shells are therefore members of a degenerate system. In the geomagnetic field, which is assumed static and without electric field, these degenerate systems are split by azimuthal asymmetry. A distinction is made, therefore, between the use of parameters as invariants of charged particie motion and their use as constants for all particles on a line of force. It is found that McIlwain's L value associates nondegenerate geomagnetic shells with dipole degenerate systems if L at a point in space is redefined to apply only to particles mirroring at that point. Emphasis is placed on the redefined L as an invariant parameter of particle motion and on the near equality of the L value of a particle and the equatorial radius R/sub o/ of the line of force on which the particle is mirroring. Although the original definition of L resulted in a very useful parameter, the present definition allows a physical interpretation of L as originally applied and extends its usefulness beyond that allowed by the original definition. With the present definition, the different values of L along a line of force can be identified with the radial separation of particles mirroring on that line as they drift in longitude. This separation is approximates 2 per cent of the shell radius and represents the accuracy with which a single magnetic field parameter, such as the minimum field intensity B/ sub O/ of a line, describes all particles on the line. Beyond 3 earth radii, it is found that R/sub O/ gives a representation of comparable accuracy. However, an invariant representation (L,B/sub m/) or (I,B/sub m/) is limited only by the accuracy of the determination of the mirror field B and the longitudinal invariant I, both of which depend on the accuracy of the magnetic field representation. (auth)

• Research Organization: Univ. of Chicago
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-031263
• OSTI ID: 4687845
• Journal Information: Journal of Geophysical Research (U.S.), Journal Name: Journal of Geophysical Research (U.S.) Vol. Vol: 68; ISSN JGREA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHARGED PARTICLES
DIPOLES
EARTH
GEOPHYSICS
MAGNETIC FIELDS
MAGNETIC MIRRORS
MOTION
PHYSICS
RADIATION BELTS
SPACE