| Autor: |
B. Wilken, Jörg Büchner, J.-P. Kuska, Qiugang Zong |
| Rok vydání: |
2013 |
| Předmět: |
|
| Zdroj: |
New Perspectives on the Earth'S Magnetotail |
| Popis: |
The GEOTAIL project has provided rich information about the ionic composition of the magnetotail in general and about the mass-dependent spectra of energetic ions in particular. These measurements have encouraged further efforts toward a better understanding of the mechanisms of particle acceleration in the magnetosphere. In order to interpret the observations quantitatively we have modeled the mass-dependence of the spectra of energetic particles, strongly accelerated by magnetotail reconnection. In the course of strong acceleration the final energy distribution of energetic particles decouples from the source distribution. We derive mass dependent energetic particle spectra parametrized by the lower energy cutoff-velocity of the spectrum and by the ratio of reconnection electric field over the asymptotic normal magnetic field. The theoretical spectra are veryfied by test particle calculations. We compare the theoretical spectra with those, observed onboard GEOTAIL. We show that energization and spectra of ionospheric origin protons and O + ions as well as of solar wind origin He ++ ions can indeed be directly explained by strong acceleration in the course of magnetotail reconnection. Our approach allows us to remotely estimate the current sheet half-thickness in the acceleration region as 1800 km and the reconnection electric field as E = 2.7 mV/m. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
