What physical mechanism do PSRs utilize to sequester volatile materials like water molecules?

Answer

Acting as cold traps where molecules become kinetically immobile

PSRs act as cold traps; once a water molecule settles in a region below a few tens of Kelvins, it becomes too cold to gain enough energy to jump out and escape into space, thus becoming permanently sequestered.

What physical mechanism do PSRs utilize to sequester volatile materials like water molecules?
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