Ion pumps have exceptional radiation tolerance.
>1E+8 Gray
Research in nuclear fusion largely involves attempts to recreate a reaction similar to that occurring in the sun by fusing two types of hydrogen, deuterium and tritium, to create helium. This requires considerable energy as the gas has to be heated to very high temperatures, up to 100 million degrees Celsius, causing it to become a plasma. Vacuum pumps partly have to operate under high radiation and magnetic field levels in those applications.