Low energy plasma cleaning method for cryofilms

摘要

Cryofilm/organic contaminants are removed from cryogenically cooled surfaces such as spacecraft cryo-telescope mirrors by sputtering and chemical reaction with a low energy plasma having an average ion energy of not more than about 30 eV, and preferably in the approximate range of 5-20 eV. When the reactive plasma's freezing point is higher than the temperature of the surface to be cleaned, the cryofilm and embedded hydrocarbons are first removed with a non-reactive plasma having a freezing point less than the surface temperature, the reactive plasma is then used to remove residual organic contaminants left on the surface by chemical reaction, and finally another inert plasma is applied to remove reactive plasma frozen to the surface; the two inert plasmas are preferably formed from the same gas.