Energetic neutral atom imaging at low altitudes from the Swedish microsatellite Astrid: Observations at low (≤10 keV) energies
Energetic neutral atom imaging at low altitudes from the Swedish microsatellite Astrid: Observations at low (≤10 keV) energies
复制标题
瑞典微卫星 Astrid 在低空进行高能中性原子成像：低能（≤10 keV）观测
DOI：
10.1029/2000ja900119
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
C. Chase
中科院分区：
文献类型：
--
作者：
P. Brandt;S. Barabash;E. Roelof;C. Chase
Intense (≤106 cm−2 sr−1 s−1) fluxes of upflowing energetic neutral atoms (ENAs) from the polar cap have been observed in the energy range ∼0.1–10 keV (hydrogen assumed) by the ENA imager PIPPI (Prelude In Planetary Particle Imaging) onboard the Astrid satellite at 1000 km altitude. If a source altitude of 400 km is assumed, the ENA emissions maps to magnetic latitudes 70°–85°extending from dusk over nightside. There were no measurements in the midnight sector below approximately 80°. It is shown that the emissions cannot originate from an isotropically emitting source, which rules out any optical emissions. Local charged particle detection is ruled out on the basis of no correlation with local electron measurements and local magnetic field configuration. The ENA emissions can be explained by a conically pitch angle distributed ion source emitting ENAs in the 110°–140°pitch angle interval (source altitude 400 km). It is suggested, with support from low altitude rocket observations that the ENAs are produced by low altitude (400–600 km) ion conies of several hundreds eV charge exchanging with the upper atmosphere.
