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Parsons, Steven; Hall, David; Hetherington, Oliver; Buggey, Thomas; Arnold, Timothy; Hubbard, Michael and Holland, Andrew
(2024).
DOI: https://doi.org/10.1117/12.3016657
Abstract
The SMILE mission, a collaborative effort between the European Space Agency and the Chinese Academy of Sciences, seeks to enhance our comprehension of the interplay between solar phenomena and the Earth's magnetosphere-ionosphere system on a global scale. Among its instrumental arsenal is the Soft X-ray Imager (SXI), designed to capture photons generated within the 200 eV to 2000 eV energy spectrum through the solar wind charge exchange process. This imaging tool employs two large CCD370s, each with 4510 x 4510 18 μm pitch pixels, as its focal plane. SMILE will orbit Earth in an elliptical trajectory, traversing the radiation belts approximately every 52 hours. Over the course of its anticipated 3-year mission, the CCDs onboard will endure progressive deterioration from the persistent presence of trapped and solar protons. To gauge the extent of this damage and its effect on the devices' functionality, a sequence of proton radiation campaigns is underway. The final cryogenic irradiation campaign has now been completed using a fully functioning engineering model of the SXI CCD370s that will be used in flight and irradiating up to the expected end of life total non-ionising dose. The results show that the measured parallel charge transfer inefficiency (pCTI) varies with temperature both before and after irradiation, however the trend changes from decreasing with temperature to increasing. This is thought to be due to a change in the dominant effective trap species. The impact of multiple charge injection lines and 6x6 binned frame transfer is also assessed and shows that between -130 to -100 °C the pCTI, when both measures are utilized, is independent of temperature. This suggests potential for more flexible thermal controls in future missions that use similar devices.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)
