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Empirical determination of extreme ultraviolet imager background
Author(s) -
Goldstein J.,
Gell D.,
Sandel B. R.
Publication year - 2017
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2017ja024301
Subject(s) - extreme ultraviolet lithography , physics , extreme ultraviolet , brightness , astrophysics , interplanetary spaceflight , ultraviolet , astronomy , solar wind , optics , plasma , laser , quantum mechanics
We present an empirical determination of background levels of 30.4 nm extreme ultraviolet (EUV) radiation. A survey of 6 months of data from the IMAGE EUV imager indicates a relatively low quiescent background level. The most probable quiescent background count rate is 2.7 per pixel, per 600 s EUV image, equivalent to a brightness of approximately 27 mR. This quiescent background rate is ≈10 times larger than the detector dark rate, indicating that quiescent background levels are dominated by external light sources or penetrating particles. We hypothesize two light sources of quiescent background in the interplanetary or interstellar medium. The first is 30.4 nm light from nonplasmaspheric He + . The second is 58.4 nm light (from neutral He) that gets past the filter/mirror. The IMAGE EUV data also exhibit episodic, factor of 3‐to‐30 increases above the quiescent background rate, throughout the 6 month data set considered herein. Comparison of these elevated background levels with solar EUV and solar wind parameters indicates several contributing causes during active periods, including solar wind energetic (50 keV to 5 MeV) particles, solar wind density/pressure, and solar 30.4 nm flux.