The extreme ultraviolet day airglow

Chakrabarti, Supriya; Paresce, Francesco; Bowyer, Stuart; Kimble, Randy A.; Kumar, Shailendra

doi:10.1029/ja088ia06p04898

Cited by 93 publications

(42 citation statements)

References 27 publications

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“…The EUVE LW spectrum of comet Hyakutake (Krasnopolsky and Mumma, 2001). 60, and 24 R, respectively (Chakrabarti et al, 1983). Therefore the above emissions are the O + lines excited, as on Earth, by photoionization.…”

Section: Euve Spectra Of Comet Hyakutakementioning

confidence: 98%

X-ray and extreme ultraviolet emissions from comets

2004

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There is significant progress in the observations, theory, and understanding of the x-ray and EUV emissions from comets since their discovery in 1996. That discovery was so puzzling because comets appear to be more efficient emitters of x-rays than the Moon by a factor of 80 000. The detected emissions are general properties of comets and have been currently detected and analyzed in thirteen comets from five orbiting observatories. The observational studies before 2000 were based on x-ray cameras and low resolution (E/δE ≈ 1.5 -3) instruments and focused on the morphology of xrays, their correlations with gas and dust productions in comets and with the solar x-rays and the solar wind. Even those observations made it possible to choose uniquely charge exchange between the solar wind heavy ions and cometary neutrals as the main excitation process. The recently published spectra are of much better quality and result in the identification of the emissions of the multiply charged ions of O, C, Ne, Mg, and Si which are brought to comets by the solar wind. The observed spectra have been used to study the solar wind composition and its variations. Theoretical analyses of x-ray and EUV photon excitation in comets by charge exchange, scattering of the solar photons by attogram dust particles, energetic electron impact and bremsstrahlung, collisions between cometary and interplanetary dust, and solar x-ray scattering and fluorescence in comets have been made. These analyses confirm charge exchange as the main excitation mechanism, which is responsible for more than 90% of the observed emission, while each of the other processes is limited to a few percent or less. The theory of charge exchange and different methods of calculation for charge exchange are considered. Laboratory studies of charge exchange relevant to the conditions in comets are reviewed. Total and state-selective cross sections of charge exchange measured in the laboratory are tabulated. Simulations of synthetic spectra of charge exchange in comets are discussed. X-ray and EUV emissions from comets are related to different disciplines and fields such as cometary physics, fundamental physics, x-rays spectroscopy, and space physics.

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Section: Euve Spectra Of Comet Hyakutakementioning

confidence: 98%

X-ray and extreme ultraviolet emissions from comets

2004

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“…This is especially true in the EUV where the solar source has a significant contribution to the airglow spectrum, making the dayglow nearly an order of magnitude brighter [Chakrabarti et at., 1983;1984]. In addition, ENAs can be several times more abundant on the nightside [Roelof, 1987] …”

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confidence: 99%

Evidence of ENA precipitation in the EUV dayglow

Stephan

Chakrabarti

Cotton

2000

Geophysical Research Letters

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“…In near-Earth orbits, the second UV source is Earth's geocorona (exospheric hydrogen atoms), by which solar photons are scattered back to space. The UV fluxes coming from the geocorona were reported to be 22-35 kR in the daytime (Chakrabarti et al, 1983) and to be 1.7-3.6 kR in the nighttime (Chakrabarti et al, 1984). Here R is a photon flux unit "Rayleigh" and 1 R is equivalent to 10 6 /4π photons/sec cm 2 sr.…”

Section: Estimation Of Uv Count Ratesmentioning

confidence: 99%

Designing a toroidal top-hat energy analyzer for low-energy electron measurement

Kazama¹

2013

An Introduction to Space Instrumentation

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This report is a brief introduction of designing an electrostatic energy analyzer by taking a toroidal top-hat energy analyzer. First, a top-hat analyzer is parameterized with four parameters: the deflection angle, the shell electrode offset, the upper collimator height and the lower collimator thickness. Then three steps of parameter surveys are made by particle trajectory tracing simulations. In the surveys, the requirements of g-factor, azimuthangle resolution and field of view are taken into accout. After the surveys, we confirm that the final design meets the requirements. In addition, UV photon suppression performance is also evaluated by photon tracintg simulations. The expected maximum photon count rate 1.59 count/sec is acceptable, compared to the MCP's background count rates. The analyzer design investigated in this report is to be taken over by a low-energy electron instrument (LEP-e) on the radiation-belt observation satellite ERG.

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The extreme ultraviolet day airglow

Cited by 93 publications

References 27 publications

X-ray and extreme ultraviolet emissions from comets

X-ray and extreme ultraviolet emissions from comets

Evidence of ENA precipitation in the EUV dayglow

Designing a toroidal top-hat energy analyzer for low-energy electron measurement

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