Short-duration Electron Precipitation Studied by Test Particle Simulation
Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard the low-altitude (680 km) polar-orbiting Korean STSAT-1 (Science and Technology SATellite). These measurements have revealed two important characteristics unique to the microbursts...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
The Korean Space Science Society
2015-12-01
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| Series: | Journal of Astronomy and Space Sciences |
| Subjects: | |
| Online Access: | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2015/v32n4/OJOOBS_2015_v32n4_317.pdf |
| Summary: | Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard
the low-altitude (680 km) polar-orbiting Korean STSAT-1 (Science and Technology SATellite). These measurements have
revealed two important characteristics unique to the microbursts: (1) They are produced by a fast-loss cone-filling process
in which the interaction time for pitch-angle scattering is less than 50 ms and (2) The e-folding energy of the perpendicular
component is larger than that of the parallel component, and the loss cone is not completely filled by electrons. To
understand how wave-particle interactions could generate microbursts, we performed a test particle simulation and
investigated how the waves scattered electron pitch angles within the timescale required for microburst precipitation. The
application of rising-frequency whistler-mode waves to electrons of different energies moving in a dipole magnetic field
showed that chorus magnetic wave fields, rather than electric fields, were the main cause of microburst events, which
implied that microbursts could be produced by a quasi-adiabatic process. In addition, the simulation results showed that
high-energy electrons could resonate with chorus waves at high magnetic latitudes where the loss cone was larger, which
might explain the decreased e-folding energy of precipitated microbursts compared to that of trapped electrons. |
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| ISSN: | 2093-5587 2093-1409 |