Premium
Pc 1 Pearl‐electron interactions on the L = 4.2 magnetic shell
Author(s) -
Arnoldy R. L.,
Kaufmann R. L.,
Cahill L. J.,
Lockheed S. B. Mende
Publication year - 1983
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl010i008p00627
Subject(s) - electron , physics , ion , electron precipitation , atomic physics , wave packet , resonance (particle physics) , computational physics , geophysics , magnetosphere , plasma , nuclear physics , quantum mechanics
A number of examples of auroral light bursts correlated with Pc 1 "pearl" wave packets have been recorded at Siple, Antarctica (L = 4.2). The events are unique in that an individual light burst occurs at Siple not when the wave packet is recorded at Siple but rather when the wave is measured to be at the conjugate point over Roberval, Quebec. Although one can fit the observations to a model where ions are precipitated from an interaction region near the equator via cyclotron resonance, the number of ions required to produce the light and the above mentioned light burst‐ULF wave phase relationship both make the precipitation of electrons a more plausible interpretation. In an electron model, electrons are precipitated at Siple which have interacted with the Pc 1 wave packet over Roberval. Because of the South Atlantic magnetic anomaly, particle mirror points are nearly 200 km deeper in the atmosphere at Siple than at Roberval. Electrons of auroral energies (few keV) can be in longitudinal resonance with the Pc 1 waves over Roberval in the altitude range where the Alfvén speed rapidly decreases (2000 → 500 km). Low parallel velocities are possible for these electrons in this altitude range because the electrons are close to their mirror points. Those electrons in longitudinal resonance with the Pc 1 wave packet must have their mirror points lowered such that they do not reach the atmosphere at Roberval but are definitely precipitated at Siple. An interesting possibility is suggested in that these events represent the acceleration of electrons by a kinetic Alfvén wave.