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A Semiempirical Monte Carlo Approach to Secondary Electron Emission from a Hydrogen-Implanted Carbon Surface

For a plasma-surface interaction, the influence of an implantation of hydrogen atoms on the secondary electron emission from a carbon surface bombarded by low-energy (<2 keV) electrons is investigated using a single scattering Monte Carlo simulation of transport of a primary electron and a semiempirical model of secondary electron emission. In the simulation, the mean escape depth, which is dependent on the hydrogen concentration in carbon, is used and the average energies deposited to excite an electron from carbon and hydrogen atoms are separately treated. The simulated secondary electron yield increases with increasing hydrogen concentration, i.e., the H/C ratio. This increase in H/C ratio of 0.5 agrees with that of a graphite limiter exposed to a hydrogen plasma in the JET Tokamak at low energy (<1 keV). Furthermore, the enhancement of the incident-angle dependence observed by exposure to the plasma is explained by the present simulation for the first time.