The experimental plan for cryogenic layered target implosions on the National Ignition Facility - The inertial confinement approach to fusion
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Ignition requires precisely controlled, high convergence implosions to assemble a dense shell of deuterium-tritium (DT) fuel with {rho}R>{approx}1 g/cm{sup 2} surrounding a 10 keV hot spot with {rho}R {approx} 0.3 g/cm{sup 2}. A working definition of ignition has been a yield of {approx}1 MJ. At this yield the {alpha}-particle energy deposited in the fuel would have been {approx}200 kJ, which is already {approx}10 x 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 {approx}10{sup 14-15} 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 {approx} Y x dsf {sup 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.
- OSTI ID:
- 21537782
- Journal Information:
- Physics of Plasmas, Vol. 18, Issue 5; Other Information: DOI: 10.1063/1.3592173; (c) 2011 American Institute of Physics; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DEUTERIUM
HYDROGEN
IGNITION
INERTIAL CONFINEMENT
PLASMA DENSITY
PLASMA DIAGNOSTICS
THERMONUCLEAR FUELS
TRITIUM
US NATIONAL IGNITION FACILITY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CONFINEMENT
ELEMENTS
FUELS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PLASMA CONFINEMENT
RADIOISOTOPES
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES