Radiation Effects

We used PSP radiation guidelines for a seven-year mission for EEE parts selection. Our designs address single event effect (SEE) induced failure (latchup, burnout, gate rupture, secondary break-down), non-destructive SEE (e.g., non-destructive latchup, minilatchup, and single event functional interrupts) and single eventinduced soft errors (including single event upsets (SEU) or transients in linear devices) and SEE-induced soft errors. All EEE parts meet the TID requirement with a minimum radiation design margin of 2°ø the mission TID (60 krad behind 100 mils of Al shielding). We use no EEE parts having a linear energy transfer (LET) threshold of <25 MeVcm2/mg (SEU) or 100 MeVcm2/mg. The selected APS detector technology (see Sect. 3.3.1) mitigates potential problems of Non-Ionizing Energy Loss (NIEL) and radiation-induced Charge Transfer Efficiency (CTE) losses. Unlike CCDs (LASCO, SECCHI/HI), the photoelectrons are read-out from each APS pixel without shifting through the rest of the detector. Like CCDs, the radiation-induced damage increases the dark current, dark current non-uniformity noise in addition to particle-induced ionization transients (“cosmic rays” are scrubbed on-board as done on SECCHI/HI), temporal variations in pixel dark current and other effects.

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Crater damage caused by dust impacts in the three glass types used in our testing. BK7 (left) is a commonly used glass type in space telescopes. BK7 with a diamond coating (DLC, middle) exhibits an additional ring around the crater possibly caused by coating separation from the glass. Sapphire (right) exhibited the least damage but it is an experimental glass type of unproven optical performance.


WISPR Pub Number 1