Achieving 280 Gbar hot spot pressure in DT-layered CH capsule implosions at the National Ignition Facility
T. Döppner, D. E. Hinkel, L. C. Jarrott, L. Massé, J. E. Ralph, L. R. Benedetti, B. Bachmann, P. M. Celliers, D. T. Casey, L. Divol, J. E. Field, C. Goyon, R. Hatarik, M. Hohenberger, N. Izumi, S. F. Khan, A. L. Kritcher, T. Ma, B. J. MacGowan, M. Millot, J. L. Milovich, S. R. Nagel, A. Pak, Jaebum Park, P. K. Patel, R. Tommasini, P. L. Volegov, C. R. Weber, O. L. Landen, D. A. Callahan, O. A. Hurricane, M. J. Edwards
Abstract
We are reporting on a series of indirect-drive 0.9-scale CH capsule implosions (inner radius = 840 μm) fielded in low gas-fill (0.6 mg/cm3) hohlraums of 6.72 mm diameter at the National Ignition Facility. Thanks to the 11%-reduction of the capsule size at a given hohlraum diameter compared to previously tested full-scale capsules, we achieved good hot spot symmetry control near 33% cone-fraction and without the need to invoke cross beam energy transfer. As a result, we achieved a hot spot pressure of 280 ± 40 Gbar, which is the highest pressure demonstrated in layered DT implosions with CH capsules to date. Pushing this design to higher velocity resulted in a reduction of neutron yield. Highly resolved capsule simulations suggest that higher Au M-shell preheat resulted in an increase in Atwood number at the ablator–ice interface, which leads to increased fuel-ablator instability and mixing. The results reported here provide important scaling information for next-generation CH designs.