Assembly of High-Areal-Density Deuterium-Tritium Fuel from Indirectly Driven Cryogenic Implosions

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of $\sim 1.0\pm 0.1\mathrm{g}{\mathrm{cm}}^{-2}$, which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1–1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275–300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of $25–35\mu \mathrm{m}$. Neutron images of the implosion were used to estimate a fuel density of $500–800\mathrm{g}{\mathrm{cm}}^{-3}$.

Figure 1

MRS data from two experiments; N110212 (preshock timing–blue points and line) and N110608 (post-shock timing–red points and line). The data have been normalized to 13–15 MeV neutron yield to allow direct comparison. Data were taken with the same MRS foil thickness and normalized to 13–15 MeV neutron yield.

Figure 2

DSR as measured by MRS (red points) and average of all down-scatter detectors (blue points) vs experiment date. The green boxes are DSR from 2D HYDRA mode 60 simulations with radiation asymmetry, measured capsule and ice roughness and drive adjusted to match the observed shock-timing results, as described in the text.

Figure 3

Plot of DSR vs $1/R_{\mathrm{HS}}{}^2$ determined from gated x-ray images at energies > 6 keV (blue points), time integrated neutron images at 13–15 MeV (tan squares) and 2D HYDRA mode 60 simulations (red dashed line). Also shown is a schematic of uniform shell model with fuel layer of thickness $\Delta r$ outside hot spot radius, $R_{\mathrm{HS}}$. The lines represent the expected dependence for various assumed values of $\Delta r/R_{\mathrm{HS}}$.

Figure 4

Plot of DT equivalent yield vs DSR for pretuned (black) and post-tuned pulses with germanium doped (blue) and silicon doped (red) CH ablators. Also shown are contours of equal ${\mathrm{ITF}}_{\mathrm{expt}}$, which increase from left to right as yield and DSR increase.