Temperature dependence of hydrogen sputtering of carbon coatings on platinum

H2+ sputtering of thin (400 to 600 A) films of C deposited on Pt is measured over the range from 20 to 8500C at an ion energy of 5 keV. The sputter yield varies from 2 x 10-2 atoms/ion at room temperature to a maximum value of 10-1 atoms/ion at 5300C. This result is compared with several previous measurements that employed bulk C targets. The differences observed are attributed largely to the effect of different experimental ion dose rates. Thus, as the dose rate increases, the maximum value of the yield decreases and the temperature at which this maximum occurs increases. This behavior is described by the model of CH4 production developed by Erents et al. The relation of these results to first wall coatings in fusion energy devices is discussed