7.1 Target Design Considerations

Users will be responsible to provide their own test objects and diagnostics for their test objects. Test objects will need to be coordinated with the NIF Materials and Radiation Effects (MRE) Engineering Team, which can provide design and fabrication assistance. The team can also provide guidance to ensure that your test objects and experiments will be within the facility capability and safety envelope or assist with the review and authorization of your experiment if it exceeds standard operating conditions.

Target assemblies must be designed to be compatible with NIF lifting/handling capability if the largest parts are such that they cannot be handled manually (e.g., >25 lbs or size/shape that cannot reasonably be handled by one individual). Target Area Operations will work with users to provide guidance on appropriate handling interfaces. A NIF rigging and handling plan must be approved by NIF engineering, with the user providing necessary input.

Sample-array target configuration
Figure 10. Sample-array target configuration. This target consists of locations for 16 individual, 40 mm diameter samples. The sample locations are evenly distributed within a 32 cm x 32 cm square.

The standard NIF DLI facility diagnostics (see Section 7.4) provide the laser fluence, uniformity, and as-delivered pulse shape to the test object. It is recommended that users field standard test coupons using their tamper material to validate the test environment and reproducibility for their data shots. For shots using an array of test coupons, it is suggested to use a “standard” configuration that can be provided by the MRE Team. The current (as of publication of this guide) configuration is shown in Figure 10. This target consists of 16 sample locations distributed over a 32 cm x 32 cm area. Each location can hold a 40 mm diameter specimen and is equipped with an optical probe to measure the rear-surface motion of the sample via Photonic Doppler Velocimetry (PDV). To obtain information on the most recent version of the sample array target or the rest of the DLI target infrastructure, users are encouraged to reach out to the MRE manager or DLI Scientific Lead.

The advantage of NIF DLI is the ability to test 3-D test objects with high spatial fluence uniformity. However, users must be aware of the usable test area (volume) and how the spatial profile of the incident fluence changes with position within the Target Chamber. For more information, see Section 6.3.