Pacific Environment is an environmental organization based in San Francisco, California, United States, founded in 1987. Its objective is to protect the living environment of the Pacific Rim.
The configurations of instruments fielded on an experiment affect the amount of information captured and the quality of subsequent inference. We investigate the problem of optimizing plasma x-ray radiation detectors in a magneto-inertial fusion experiment at Sandia National Laboratories. It is impossible to directly measure properties such as the temperature of the thermonuclear fusion plasma produced in these experiments because of the extreme environment and destructive nature of the experiment. Among other diagnostics, several detectors are placed with significant standoff from the fusion target to capture the x-rays emitted by the fusion plasma, which can be used to infer some of its properties. To optimize the configuration of these detectors, a high-fidelity model (HFM) is used for simulating outputs and a low-fidelity model (LFM) is used for inference. We develop methods based on A- and L-optimality criteria that are efficient to compute while explicitly accounting for the discrepancy between the HFM and the LFM. The method allows us to find detector configurations that perform similarly to or better than the configuration obtained using an existing sampling-based optimization method while decreasing computational time by a factor of 50. Supplementary materials for this article are available online, including a standardized description of the materials available for reproducing the work.
Conodont faunas from the Castillion Member of the Selish Formation (Nicola Group) in the Merritt area of southern British Columbia, Canada, are described and determined to be early to mid-Norian in age based on biozonation established in the Pardonet Formation in NE British Columbia supported by successions in central Europe. The conodonts from two localities (Iron Mountain, Castillion Creek) show evolutionary trends through a younging sequence that serve to date and subdivide it. Hence, Ancyrogondolella vialovi is succeeded by A. ferrata n. sp. at Iron Mountain, and A. castillionensis n. sp. follows at Castillion Creek. Similarly, A. triangularis n. subsp. B is succeeded by A. diakowi, and A. uniformis is followed by A. equalis and Epigondolella tozeri. Finally, A. transformis appears as an end member and index for the Lacian-Alaunian substage boundary zone. Zircons extracted from interbedded volcaniclastics of the Castillion Member have yielded high-precision U-Pb ages of similar to 224.5 Ma for the transformis Zone. This unequivocally supports the 'long Norian' with its base at similar to 227 Ma but contrasts strongly with the astrochronologic estimate of 217.5 Ma for base Alaunian, which appears to consume most of Norian time. There is no clear explanation for this discrepancy.
Z-pinches have regained interest as a potential pathway to fusion conditions, driven by recent advances in high-current generators and in experimental capabilities. Among various configurations, the Staged Z-pinch concept employs high-atomic number liners to enhance radiative effects during compression. Radiation plays a critical role in both the preheating of the target and the compression of the liner, which, in turn, influences the target conditions in stagnation. In this work, an analytical framework on radiative compressional waves is applied to the design of radiative Z-pinch implosions, demonstrating how radiation effects vary with the Boltzmann number and the optical thickness of the liner. This analysis provides a foundation for identifying an optimized parameter space for high-Z liner implosions, focusing on liner compression and target preheating in one-dimensional models. Future extensions to two and three dimensions will assess the impact of radiation on the development of the Rayleigh–Taylor instability.
