NIF experiments are typically executed via experimental “platforms.” A NIF experimental platform typically consists of an integrated laser set up, target design, data analysis plan, classification level, and diagnostic configuration capable of providing well-characterized pressure, temperature, radiation or implosion-trajectory conditions.
A number of new experimental platforms are commissioned each year. Once developed, an experimental platform can be customized and applied to a wide variety of physics experiments. For example, a planar-radiation hydrodynamics platform, with some modifications, could be applied to both an experiment studying the formation of the Eagle Nebula pillars and an experiment looking at the formation of Herbig– Haro jets.
Proposed NIF experiments are matched to existing platforms and capabilities whenever possible. Because of the lead times for developing new platforms, experimentalists are encouraged to use an existing platform when possible. The closer an experiment stays to an established platform, the less lead time is needed and the more readily data can be acquired. Any platform modifications or new capabilities needed to perform the experiment must be identified at an early stage and discussed with the facility stakeholders.
For more information on the platforms, see the Users section of the NIF website (https://lasers.llnl.gov/for-users/experimental-capabilities).
Changes to the NIF laser system may be organized into those that require months to make, those that can be accomplished in more than one shift, and those that can fit into a single shot cycle. The list below summarizes the characteristics of some of these changes
Examples of laser capabilities that can be modified during the shot cycle:
- Temporal pulse shape
- SSD bandwidth
- Laser energy
Pointing of individual beams
Examples of laser capabilities that require multiple shifts to reconfigure:
- >8 CPPs exchanged
- Special laser diagnostic reconfigurations
- Polarization smoothing changes (quite a few shifts
Examples of laser capabilities that are not precluded but that may require large resource and time commitments:
- 2D SSD
- Conversion to 2w operation
- Moving beams to direct-drive ports
Although a unique experimental platform for each study might be attractive, it should be remembered that the greater the number of facility modifications requested between shots, the lower the shot rate. Users are allocated blocks of time following a successful proposal, so it is up to the user to measure complexity in their setup against the number of shots they can accomplish.