Effects Of The Space Environment On The Performance Of SMILE SXI CCDs

Buggey, Thomas (2021). Effects Of The Space Environment On The Performance Of SMILE SXI CCDs. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.00013d70

Abstract

This thesis investigates the effects of the hazardous space environment on the performance of SMILE SXI CCDs, split between the roles of radiation and micrometeoroid damage. The radiation damage work focuses on developing an analytical technique to guide experimental CCD charge transfer optimisation, which is often a significantly time-consuming process. The technique is initially used to inform SXI CCD optimal clocking speeds and subsequently used to predict in-orbit performance benefits of different CCD operation modes. The first key result was the predicted charge transfer performance improvement from implementing tri-level clocking in the SMILE CCDs being less than 7%, which led to the decision to not implement it in the drive electronics. The second key result, related to radiation damage in a cryogenically irradiated CCD280, was the analysis of an unstable defect found to have a half-life of approximately 4 hours. The final key result is that the thermal cycling of SXI in-orbit will not have a noticeable effect on the defect landscape and hence CTI during the 3-year science lifetime.

The micrometeoroid work focuses on development of a framework to quantify the effects of micrometeoroid impacts in CCD-based soft X-ray space telescopes. The work is tailored specifically for SMILE SXI but can be used in future CCD-based soft X-ray space missions, or any mission that will use silicon micropore optics. The key result of the analysis was the prediction that between 20 and 100 micrometeoroids of a least 1×10^-6 m diameter will strike the CCDs of SMILE SXI over 3 years. Additional analysis was carried out using crater damage equations to estimate the number of pixels affected by the number of micrometeoroid impacts stated above. Finally, a bespoke experimental setup was built and tested by the author, in preparation for a micrometeoroid experiment testing campaign.

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