parameter indicative of the performance with respect to ignition. An implosion with ITFx = 1 has a 50 percent probability of ignition. It can be shown9 that the ITFx represents the third power of the Lawson criterion ITFx = [(Pτ)/(Pτ)ig ]3, where (Pτ)ig (T) is a function of temperature, representing the minimum product Pτ required for ignition at a given temperature.10 For the indirect-drive point-design target with 0.17 mg of DT fuel, the ITFx can be expressed11 in terms of the measured areal density and neutron yield according to

image

Both the areal density and neutron yield are the so-called no-burn or no-alpha values as they are related solely to the hydrodynamic compression without accounting for alpha particle energy deposition. To date, the highest value of the ITFx is about 0.1 from implosions, with areal densities and neutron yields in the range 0.8-1.2 g/cm2 and 5-8 × 1014 respectively12

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9 R. Betti, 2012, “Theory of Ignition and Hydroequivalence for Inertial Confinement Fusion, Overview Presentation,” OV5-3, 24th IAEA Fusion Energy Conference, October 7-12, San Diego, Calif.; B. Spears, S. Glenzer, M.J. Edwards, et al., 2012, Performance metrics for inertial confinement fusion implosions: Aspects of the technical framework for measuring progress in the National Ignition Campaign, Physics of Plasmas 19: 056316.

10 R. Betti, P.Y. Chang, B.K. Spears, et al., 2010, Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinement, Physics of Plasmas 17: 058102; R. Betti, “Theory of Ignition and Hydroequivalence for Inertial Confinement Fusion, Overview Presentation,” OV5-3, 24th IAEA Fusion Energy Conference, October 7-12, San Diego, Calif.

11 B. Spears, S. Glenzer, M.J. Edwards, et al., 2012, Performance metrics for inertial confinement fusion implosions: Aspects of the technical framework for measuring progress in the National Ignition Campaign, Physics of Plasmas 19: 056316.

12 S. Glenzer, D.A. Callahan, A.J. MacKinnon, et al., 2012, Cryogenic thermonuclear fuel implosions on the National Ignition Facility, Physics of Plasmas 19: 056318; J. Edwards, et al., 2012, “Progress Towards Ignition on the National Ignition Facility,” MR1.00001, 54th Annual Meeting of the American Physical Society, Division of Plasma Physics, Philadelphia, Pa., October 29-November 2.



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