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Helium cyclotron resonance within the Earth's magnetosphere
Author(s) -
Mauk B. H.,
McIlwain C. E.,
McPherron R. L.
Publication year - 1981
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/gl008i001p00103
Subject(s) - cyclotron , cyclotron resonance , magnetosphere , physics , ion cyclotron resonance , fourier transform ion cyclotron resonance , helium , atomic physics , ion , proton , nuclear physics , plasma , quantum mechanics
A histogram of electromagnetic Alfven/ion cyclotron wave frequencies, sampled within the geostationary environment and normalized by the equatorial proton cyclotron frequency, shows a dramatic gap centered near the helium (He + ) cyclotron frequency. Also, strongly cyclotron phase bunched helium ions (20‐200 eV) have been observed directly within the vicinity of wave environments. These observations are interpreted as resulting from the absorption of the waves through cyclotron resonance by cool ambient populations of helium ions.