Generalized Measurable Ignition Criterion for Inertial Confinement Fusion

A multidimensional measurable criterion for central ignition of inertial-confinement-fusion capsules is derived. The criterion accounts for the effects of implosion nonuniformities and depends on three measurable parameters: the neutron-averaged total areal density (ρRₙᵗᵒᵗ), the ion temperature (Tₙ), and the yield over clean (YOC=ratio of the measured neutron yield to the predicted one-dimensional yield). The YOC measures the implosion uniformity. The criterion can be approximated by χ=(ρRₙᵗᵒᵗ)0.8(Tₙ/4.7)1.7YOC^μ>1 (where ρR is in g cm^-2, T in keV, and μ≈0.4--0.5) and can be used to assess the performance of cryogenic implosions on the NIF and OMEGA. Cryogenic implosions on OMEGA have achieved χ~0.02--0.03.