A mechanism for the production of certain types of very-low-frequency emissions
It was shown that some types of v-l-f emissions (hooks, risers, and falling tones) may be the result of cyclotron emission by energetic electrons trapped in the earth's magnetic field. Observational evidence suggests that a relatively intense electromagnetic whistler-mode wave may be necessary to trigger each such emission. An interaction mechanism is proposed by which certain electrons may couple with a wave already propagating along the same line of force. A gyroresonance is established that organizes the electrons so that cyclotron radiation can be coherent. A change in phase relation occurs for those electrons that have a longitudinal velocity component such that the Doppler-shifted frequency of the whistler wave seen by the electron is equal or nearly equal to the electron gyrofrequency. This condition is met by electrons moving in a direction opposite to the whistler wave and is satisfied only over a certain fraction of the line of force. Observations also show instances of a sudden change in slope of the rising tail of a hook or other v-l-f emission at the crossing of the spectrums of the emission and a whistler. This change is interpreted as the effect of the encounter of a whistler with the electron stream that changes both energy and pitch angle of the emitting electrons. (auth)
- Research Organization:
- National Bureau of Standards, Boulder, Colo.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-041684
- OSTI ID:
- 4689110
- Journal Information:
- Journal of Geophysical Research, Vol. 68, Issue 21; Other Information: Orig. Receipt Date: 31-DEC-63; ISSN 0148-0227
- Publisher:
- American Geophysical Union
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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