"Sputtering" of Ice by MeV Light Ions

Abstract

We have measured the rate of erosion of thin films of water ice at low temperatures by bombardment with MeV hydrogen, helium, carbon, and oxygen ions. The effective "sputtering coefficients" are orders of magnitude higher than those anticipated from conventional sputtering theories. For example, for helium at 1.5 MeV, \ensuremath{\sim}10 ${\mathrm{H}}_{2}$O molecules are removed for each incident ion. We believe that the erosion process is closely associated with atomic ejection following ionization in the region near the surface.