The experimental plan for cryogenic layered target implosions on the National Ignition Facility—The inertial confinement approach to fusion

Abstract

Ignition requires precisely controlled, high convergence implosions to assemble a dense shell of deuterium-tritium (DT) fuel with ρR>∼1 g/cm2 surrounding a 10 keV hot spot with ρR ∼ 0.3 g/cm2. A working definition of ignition has been a yield of ∼1 MJ. At this yield the α-particle energy deposited in the fuel would have been ∼200 kJ, which is already ∼10 × more than the kinetic energy of a typical implosion. The National Ignition Campaign includes low yield implosions with dudded fuel layers to study and optimize the hydrodynamic assembly of the fuel in a diagnostics rich environment. The fuel is a mixture of tritium-hydrogen-deuterium (THD) with a density equivalent to DT. The fraction of D can be adjusted to control the neutron yield. Yields of ∼1014−15 14 MeV (primary) neutrons are adequate to diagnose the hot spot as well as the dense fuel properties via down scattering of the primary neutrons. X-ray imaging diagnostics can function in this low yield environment providing additional information about the assembled fuel either by imaging the photons emitted by the hot central plasma, or by active probing of the dense shell by a separate high energy short pulse flash. The planned use of these targets and diagnostics to assess and optimize the assembly of the fuel and how this relates to the predicted performance of DT targets is described. It is found that a good predictor of DT target performance is the THD measurable parameter, Experimental Ignition Threshold Factor, ITFX ∼ Y × dsf 2.3, where Y is the measured neutron yield between 13 and 15 MeV, and dsf is the down scattered neutron fraction defined as the ratio of neutrons between 10 and 12 MeV and those between 13 and 15 MeV.

$$\mathrm{ND}^2\mathrm{AV}$$ ND 2 AV : N-dimensional data analysis and visualization analysis for the National Ignition Campaign

“…The filter module allows a user to select data based on an arbitrary numpy [28] expression as well as to choose subsets of the given variables to use for analysis. Additionally, we allow users to enter an arbitrary expression to create a custom function, or to choose from some pre-loaded important indicator functions such as ITF [16] and ITFX [38] used extensively in the NIC. If desired, the module will automatically normalize the domain values to create a common frame of reference by scaling each axis according to either its range or standard deviation.…”

Self-consistent inclusion of classical large-angle Coulomb collisions in plasma Monte Carlo simulations

“…This modification still allows for the use of the replacements in the GMS6 ln Λ. Similarly, any theory restricted in angle and including extra corrections due to long-distance, small-angle effects could be used in place of equation (8).…”

“…This regime also includes inertial confinement fusion (ICF) [6,7], as an igniting ICF hotspot will have conditions [8] of areal density and temperature of ∼0.3 g/cm 2 and ∼10 keV respectively, which correspond to small values of ln Λ for a typical hotspot radius of tens of microns.…”

Quantifying “cliffs” in design space

“…The first is the ignition of a flammable gas mixture by a small spark. This is a simple model of the more complex problem of ignition of a laser fusion capsule (Chang, et al 2010;Lindl, et al 2011;Haan, et al 2011;Edwards, et al 2011). The second is the well-known problem of plastic failure of a ductile material in tension (Ugural and Fenster 2011).…”