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

Abstract

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g 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 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

Nuclear imaging of the fuel assembly in ignition experiments

“…8(a), were obtained by postprocessing 28 2D integrated hohlraum simulations, 29 where the radiation drive was tuned to match shock speed data from shock-timing experiments, 30 radius vs. time data from convergent ablator experiments, 31,32 and bang-time data from cryogenically layered deuterium-tritium implosions. 5,6,11 We have also generated synthetic images from high-resolution 2D capsule-only simulations 33 and the results are consistent with those presented. The simulated images were smoothed with a 10 lm FWHM Gaussian function to approximately match the diagnostic resolution of 12 lm, followed by the same analysis of the 17% contour as was done for the data.…”

“…To optimize the experimental program, the National Ignition Campaign (NIC) was created with a defined set of goals, requirements, and experimental plans. [2][3][4] During 2011, initial results from the NIC experimental program were published by Glenzer et al 5 and Mackinnon et al 6 Results from ignition experiments performed between December 2011 and September 2012, referred to below as the 2012 data set, are reported here. These results focus on nuclear performance with emphasis on the size and shape of the implosion using the neutron imaging diagnostic.…”

Observation of strong electromagnetic fields around laser-entrance holes of ignition-scale hohlraums in inertial-confinement fusion experiments at the National Ignition Facility

“…Such an exciting scientific breakthrough is being vigorously pursued at the National Ignition Facility (NIF) [5] through the indirect-drive approach, in which the capsule implosion occurs in response to tremendous radiation pressure generated by the thermal x-rays in a high-Z enclosure, i.e. hohlraum, when the enclosure's inner wall is irradiated by high-power lasers [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The lasers would have a temporal pulse shape designed to launch four radially convergent shock waves which would coalesce at the capsule center, creating a self-igniting 'hot spot' which would generate a self-sustaining burn wave that propagates into the main fuel region.…”

National Ignition Campaign Program Completion Report

“…Improved shock timing [47] along with extended pulses to maximize the imploding shell density prior to stagnation has resulted in two discrete jumps in fuel ρr, which has reached about 85% of the point design value. Progress toward ignition can be graphically represented as shown in the left-hand chart in Figure 3-13, where cryogenic layered target neutron yield is plotted versus the DSF and where the contours drawn represent constant ITFX.…”