Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility.


An accurate understanding of burn dynamics in implosions of cryogenically layered deuterium (D) and tritium (T) filled capsules, obtained partly through precision diagnosis of these experiments, is essential for assessing the impediments to achieving ignition at the National Ignition Facility. We present measurements of neutrons from such implosions. The apparent ion temperatures T_{ion} are inferred from the variance of the primary neutron spectrum. Consistently higher DT than DD T_{ion} are observed and the difference is seen to increase with increasing apparent DT T_{ion}. The line-of-sight rms variations of both DD and DT T_{ion} are small, ∼150eV, indicating an isotropic source. The DD neutron yields are consistently high relative to the DT neutron yields given the observed T_{ion}. Spatial and temporal variations of the DT temperature and density, DD-DT differential attenuation in the surrounding DT fuel, and fluid motion variations contribute to a DT T_{ion} greater than the DD T_{ion}, but are in a one-dimensional model insufficient to explain the data. We hypothesize that in a three-dimensional interpretation, these effects combined could explain the results.

DOI: 10.1103/PhysRevE.94.021202

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@article{Johnson2016IndicationsOF, title={Indications of flow near maximum compression in layered deuterium-tritium implosions at the National Ignition Facility.}, author={M Gatu Johnson and James P. Knauer and Charles J. Cerjan and M. J. Eckart and Gary P Grim and Edward P. Hartouni and R . Hatarik and Joseph D Kilkenny and David H Munro and D. B. Sayre and Brian K. Spears and Richard M. Bionta and Essex J. Bond and Joseph A Caggiano and Debra A Callahan and Daniel Thomas Casey and Tilo D{\"{o}ppner and Johan A. Frenje and Vladimir Yu Glebov and Omar A. Hurricane and Andrea L Kritcher and S. Lepape and Tammy Ma and Andrew J. Mackinnon and Nathan B. Meezan and Pravesh K. Patel and Richard D. Petrasso and Joseph E Ralph and Paul T. Springer and Charles B. Yeamans}, journal={Physical review. E}, year={2016}, volume={94 2-1}, pages={021202} }