Figure 6 shows the carbon sputtering yield as a function of incident ion energy due to H, D, and T ions at target temperatures of 800 K. It is clear that the sputtering values of T ions are the largest and those of H are the smallest. The sputtering values of T ions are approximately three to five times larger than that of D ions, and the sputtering values of D ions are approximately three to ten times larger than those of H ions. These results are due to the weight of the incident particles. Of the isotopes of hydrogen, the mass of H is smallest, so for the same incident energy, the H ions have the fastest speed compared to that of D and T ions. Therefore, H ions have the largest incident depth. Before the hydrogen atoms transfer their energy to the target atoms on the surface, they lose the most energy among hydrogen isotopes; therefore, the sputtering values of H ions are the smallest. In the same way, we can explain why the sputtering values of T ions are the largest. According to above results, the peak values of the sputtering yield locate between 25 eV and 50 eV. Furthermore, we choose to bombard graphite with 25 eV H, D, and T ions at 300 K to examine sputtering yield variations with the angle of the incident ions. Figure 7 shows the carbon sputtering yield as a function of incident angle for graphite bombarded by 25 eV H, D, and T ions at 300 K. The figure shows the sputtering yields increase gradually with the incident angle below 30 deg. When the incident angle is greater than 30 deg, the sputtering yield remains steady. As the incident angle increases, the velocity in the *Z*-direction decreases and the velocity in the *X*- and *Y*-directions increases, so there are more collisions between the surface carbon atoms and incident ions; thus, the sputtering yield increases below the 30 deg and remains steady after that.