Stability of sputtered Mo/BN, W/BN, Mo/B4C and W/B4C soft X-ray multilayers under exposure to multipole-wiggler radiation

The effect of white wiggler radiation exposure on Mo/BN, W/BN, Mo/B4C, and W/B4C multilayers was evaluated by comparing soft X-ray reflectance. All samples were prepared by magnetron sputtering onto SiC substrates. The choice of combinations was based upon thermal annealing tests for Mo/X and W/X (X=C, Si, BN, and B4C) multilayers, prior to any exposure tests. On exposure under radiation power density of ∝2.3 W/mm2 for ten minutes the Mo/BN and W/BN samples underwent ∝20% and ∝65% degradation in reflectance, while the Mo/B4C and W/B4C samples were almost destroyed. Of the four samples the Mo/BN multilayer was the most stable. The result was qualitatively consistent with that of the anneal tests. (orig.)