Analyses with XRD and XPS were made for the r.f magnetron sputtering deposited carbon film on tungsten substrate before and after Ar and N ions irradiation.It is found that the microstructure of the carbon film depends on the bombarding ion species. The r.f magnetron sputtering deposited carbon films are amorphous. While the N ion irradiation can induce the formation of C-N and N-W crystalline compounds
the Ar ion irradiation can not induce such a phase transformation. But the latter can effectively reduce oxygen contamination. With increase of Ar ion doses
the content of the contaminating oxygen is decreased. The related mechanism was also discussed in the paper.