scholarly journals Imaging global auroras in space

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
A. T. Y. Lui

Abstract China’s initial participation in the global monitoring of auroras for scientific and space weather investigations has been enabled by the successful launch of the Chinese Fengyun-3D satellite, which carries a wide-field auroral imager.

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiao-Xin Zhang ◽  
Bo Chen ◽  
Fei He ◽  
Ke-Fei Song ◽  
Ling-Ping He ◽  
...  
Keyword(s):  

2020 ◽  
Author(s):  
Fei He ◽  
Xiao-Xin Zhang ◽  
Zhonghua Yao ◽  
Yong Wei ◽  
Weixing Wan

<p><span lang="EN-US">Transpolar arcs that occur primarily under northward interplanetary magnetic field (IMF) are a class of auroral features in the polar cap region. Many mechanisms have been proposed to interpret the generation of the arcs, including reconnection and sudden change in the IMF. It is now generally accepted that IMF B<sub>Y</sub>component plays a key role in the generation and evolution of the arcs. Here we report an interesting long-lasting and moving transpolar arc observed during a geomagnetically quiet period (Dst<10 nT and AE<50 nT) by the wide-field auroral imager (WAI) onboard the Chinese Fengyun satellite. The WAI is a recently launched imager operated in far ultraviolet wavelength (LBH band in 140-180 nm) in a sun-synchronous orbit with a height of ~840 km. It is shown that the arc was initiated at the poleward auroral boundary on dawnside after the IMF turned to be northward and persisted for more than 5 hours. The arc moved toward the noon-midnight line as the IMF B<sub>Y</sub>component changed its direction and then moved back toward dawnside. An interesting phenomenon was that the arc was accompanied with strong energetic proton (30-80 keV) precipitations with geomagnetic latitude greater than 70° but no significant electron precipitations. However, the origin of these energetic protons is unknown and is worthy study in future.</span></p>


2007 ◽  
Vol 25 (2) ◽  
pp. 519-532 ◽  
Author(s):  
N. P. Bannister ◽  
E. J. Bunce ◽  
S. W. H. Cowley ◽  
R. Fairbend ◽  
G. W. Fraser ◽  
...  

Abstract. A comprehensive understanding of the solar wind interaction with Earth's coupled magnetosphere-ionosphere system requires an ability to observe the charged particle environment and auroral activity from the same platform, generating particle and photon image data which are matched in time and location. While unambiguous identification of the particles giving rise to the aurora requires a Low Earth Orbit satellite, obtaining adequate spatial coverage of aurorae with the relatively limited field of view of current space bourne auroral imaging systems requires much higher orbits. A goal for future satellite missions, therefore, is the development of compact, wide field-of-view optics permitting high spatial and temporal resolution ultraviolet imaging of the aurora from small spacecraft in low polar orbit. Microchannel plate optics offer a method of achieving the required performance. We describe a new, compact instrument design which can observe a wide field-of-view with the required spatial resolution. We report the focusing of 121.6 nm radiation using a spherically-slumped, square-pore microchannel plate with a focal length of 32 mm and an F number of 0.7. Measurements are compared with detailed ray-trace simulations of imaging performance. The angular resolution is 2.7±0.2° for the prototype, corresponding to a footprint ~33 km in diameter for an aurora altitude of 110 km and a spacecraft altitude of 800 km. In preliminary analysis, a more recent optic has demonstrated a full width at half maximum of 5.0±0.3 arcminutes, corresponding to a footprint of ~1 km from the same spacecraft altitude. We further report the imaging properties of a convex microchannel plate detector with planar resistive anode readout; this detector, whose active surface has a radius of curvature of only 100 mm, is shown to meet the spatial resolution and sensitivity requirements of the new wide field auroral imager (WFAI).


2020 ◽  
Vol 10 ◽  
pp. 37
Author(s):  
Leon Golub ◽  
Peter Cheimets ◽  
Edward E. DeLuca ◽  
Chad A. Madsen ◽  
Katharine K. Reeves ◽  
...  

Accurate predictions of harmful space weather effects are mandatory for the protection of astronauts and other assets in space, whether in Earth or lunar orbit, in transit between solar system objects, or on the surface of other planetary bodies. Because the corona is multithermal (i.e., structured not only in space but also in temperature), wavelength-separated data provide crucial information that is not available to imaging methods that integrate over temperature. The extreme ultraviolet (EUV) wavelengths enable us to focus directly on high temperature coronal plasma associated with solar flares, coronal mass ejections (CMEs), and shocked material without being overwhelmed by intensity from the solar disk. Both wide-field imaging and spectroscopic observations of the solar corona taken from a variety of orbits (e.g., Earth, L1, or L5) using suitably-chosen EUV instrumentation offer the possibility of addressing two major goals to enhance our space weather prediction capability, namely: (1) Improve our understanding of the coronal conditions that control the opening and closing of the corona to the heliosphere and consequent solar wind streams, and (2) Improve our understanding of the physical processes that control the early evolution of CMEs and the formation of shocks, from the solar surface out into the extended corona.


Author(s):  
M. G. Lagally

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.


Space Weather ◽  
2004 ◽  
Vol 2 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Anna Belehaki ◽  
Jean Lilensten ◽  
Toby Clark
Keyword(s):  

Space Weather ◽  
2003 ◽  
Vol 1 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Robert Robinson
Keyword(s):  

Space Weather ◽  
2005 ◽  
Vol 3 (1) ◽  
pp. n/a-n/a
Author(s):  
Sarah Simpson
Keyword(s):  

Space Weather ◽  
2004 ◽  
Vol 2 (12) ◽  
pp. n/a-n/a
Author(s):  
Jonathan Lifland
Keyword(s):  

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