Our theoretical results have demonstrated the usefulness of diamond films for improving the survivability of thin film metal mirrors against intense x-ray. Essentially, the low-Z, high thermal conductivity diamond film acts as an efficient heat sink, thus reducing the temperature in the metal film. Specifically, for an aluminum/fused silica mirror, our analysis has shown that interposing a 1-μm thick diamond film between the thin film aluminum and SiO2 substrate increases the aluminum melt fluence--from a 1 KeV black body, 10 ns x-ray pulse--by a factor of 6. In addition, we have found that for pulse widths on the order of about 10 ns, a diamond film thickness of about 1 μm appears to be most effective in reducing the aluminum temperature.
"Diamond Films For Improving Survivability Of Thin Film Metal Mirrors Against X-Ray", Proc. SPIE 0969, Diamond Optics, (17 January 1989); doi: 10.1117/12.948158; https://doi.org/10.1117/12.948158