Observation of AKR generation as a self-oscillating system
Abstract
Auroral kilometric radiation (AKR) is a powerful natural electromagnetic radio emission in the frequency range of 30 kHz to ~ 1 MHz which is generated in the near-Earth plasma and propagated from the Earth. AKR is connected with discreet auroras and its sources are situated above the auroral ionosphere, generally, in the evening and night sectors of the magnetosphere at invariant latitudes of ~ 700 , at a height of ~ 2-10 thousand kilometers, and also in the magnetospheric cusp. AKR is generated by energetic electron beams injected from the magnetotail into the auroral zone. Currently, cyclotron maser instability at the local electron gyrofrequency is considered to be a generally recognized mechanism of AKR generation. Such instability appears in the regions with low plasma density called Calvert’s cavity where plasma frequency fpe is lower than electron gyrofrequency fce. Auroral kilometric radiation is generally observed in the frequency range of 100 - 700 kHz, and AKR spectrum width changes slowly during several dozens of minutes. We present results of the analysis of wide-band AKR structures obtained by the POLRAD experiment on board the INTERBALL-2 satellite. These structures represent a quasiperiodic sequence of splashes which more often observed at the beginning and end of AKR radiation interval. The main properties of such splashes and their possible mechanism of generation are discussed.
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E2151M