X-RAY RESPONSE OF NATIONAL-IGNITION-FACILITY FIRST SURFACE MATERIALS

The ablation of first surface materials by x rays is a primary threat to the final optics in the NIF target chamber. To meet the operational goals of the facility, the designs of the chamber wall, target holder and diagnostic surfaces must minimize ablation by x rays, typically b y specifying materials that ate low-Z, high temperature resistant, and shock resistant. Additionally, the response of the optics to direct t arget emissions must be understood. This paper describes some experime ntal and modeling work to develop the validated computer models necess ary to quantify the x-ray response of various materials. These codes a nd further experiments will then confirm the ability of NIF first surf ace designs to meet functional requirements.