Bibliography

Design of FUV imaging spectrometer based on crossed Czerny-Turner structure

This article describes the characteristics of the far ultraviolet (FUV) radiation and its applications in the space weather s research and prediction. The FUV imaging spectrometer is irreplaceable to get the FUV radiation data of the earth s upper atmosphere. Some key technologies of FUV spectrometer are analyzed respectively, including window materials, FUV light source, FUV detectors and FUV coating, which offer theoretical foundation for FUV imaging spectrometer. The paper presents a FUV band imaging spectrometer s optical system which is based on crossed Czerny-Turner structure with all reflective components in it. The wavelength range of the FUV spectrometer optical system is from 100nm to 200nm and the initial structure is simulated and optimized by Zemax in order to improve the spectral resolution. The theoretical spectral resolution of the system is better than 1nm, and it has a certain imaging capacity.

Wu, Yan; Tang, Yi; Ni, Guoqiang; Sheng, Yunlong; Wang, Yongtian; Zeng, Lijiang;

Published by:       Published on:

YEAR: 2009     DOI: 10.1117/12.806967

space weather; far ultraviolet; Imaging spectrometer; crossed Czerny-Turner system; optical design

Compact FUV camera concept for space weather applications

Far ultraviolet (FUV) images of Earth from space have proven invaluable in revealing contextual phenomena associated with space weather in the high latitude auroral regions and in the mid and equatorial regions. Images of this nature can be used to investigate compelling questions associated with the interaction of the ionosphere/mesosphere-magnetosphere-solar wind. Observations using images that lead to quantitative analyses are required to significantly advance the state of knowledge with regard to the affects of space weather and the interaction between and within these regions of Geospace. Current available image data sets are sufficient for qualitative analysis and morphological investigations, and while quantitative analyses are possible, they are difficult and limited to few events at best^1,2. In order to qualitatively access the time, spatial, and causal phenomena on global scales, simultaneous images of various FUV emissions with a combination of better spatial, temporal and spectral resolution and sensitivity than currently available are required. We present an instrument concept that is being developed to improve the spatial, temporal and spectral resolution and sensitivity needed to perform the quantitative analysis that enable significant advancement in our understanding of the impact of space weather on Geospace. The approach is to use the "self-filtering" concept³ that combines the imaging and filtering functions and thus reduces the size of the 4-mirror off-axis optical system. The optical and filter design will de described.

Spann, James; Fineschi, Silvano; Viereck, Rodney;

Published by:       Published on:

YEAR: 2005     DOI: 10.1117/12.615201

Camera; Filters; far ultraviolet; space weather; MI coupling; Ionosphere; AURORA; Geospace

Quiet-time seasonal behavior of the thermosphere seen in the far ultraviolet dayglow

The TIMED/GUVI instrument is a far ultraviolet spectrograph that obtains images in five spectrally resolved wavelength channels. These images yield information on the dayside composition, temperature, solar EUV flux, large-scale wave structures, and auroral processes. In this paper we present an overview analysis of Earth-disk images for four seasons (March, July, and September 2002 and January 2003). Days were selected during geomagnetically quiet periods when the Sun was nearly in the orbital plane (noon orbits). Two of GUVI\textquoterights five channels (designated as 135.6 and LBH_S and dominated by OI 135.6 nm and short wavelength N₂ LBH band emission, respectively) are used when the instrument is in its imaging mode. These data are used to derive O/N₂ (column density ratio referenced to an N₂ column density of 10¹⁷ cm^-2). The AURIC model is used to generate a lookup table that relates O/N₂ to the ratio of 135.6 to LBH_S for a given solar zenith angle. Global images of derived O/N₂ (designated as GUVI O/N₂) are presented for the 4 days. The initial validation of the retrieved composition ratio comes from comparison with the NRLMSIS model. Good overall qualitative agreement is obtained between GUVI and NRLMSIS. Both data and model exhibit similar latitudinal behaviors on the near-solstice days, namely a distinct gradient with O/N₂ decreasing from the winter to the summer hemisphere. Reductions in O/N₂ in the vicinity of magnetic poles are seen in both GUVI and NRLMSIS images. Globally, O/N₂ is smaller at the solstices and may be explained by the \textquotedblleftthermospheric spoon\textquotedblright mechanism discussed by Fuller-Rowell [1998]. Alternatively, the greater overall values at the equinoxes may arise in part from global response to greater Joule heating at these times of the year. The sensitivity of O/N₂ to scalings of the N₂ LBH cross section and solar EUV below 20 nm is also addressed in response to recent papers on these topics. This initial look at the GUVI data demonstrates great promise of FUV remote sensing as a way to observe thermospheric composition changes over broad geographic scales.

Strickland, D.; Meier, R.; Walterscheid, R.; Christensen, A.; Paxton, L.; Morrison, D.; Craven, J.; Crowley, G.;

Published by: Journal of Geophysical Research      Published on: 01/2004

YEAR: 2004     DOI: 10.1029/2003JA010220

far ultraviolet; remote sensing; seasonal behavior; thermosphere