CCD Bakeouts
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Sometimes, SOHO's extreme ultraviolet (EUV) telescope goes offline for a "CCD Bakeout." What's that all about?

Answer: Heating the telescope's CCD detector counteracts the degrading effects of exposure to solar wind and cosmic rays.

According to SOHO documentation, "Over time, many types of CCDs (Charge-Coupled Devices) used to detect EUV radiation are degraded by contamination of heavy ions from cosmic/solar particle radiation (interfering with the doping of the chip), deposits and polymerisation of deposits on the surface and, finally, trapped charges (again interfering with the doping of the substrate). These forms of degradation reduce the sensitivity of the detector. Fortunately, by heating the CCD over an extended time period, some of these effects can be reduced."

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