Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinement

The physics of thermonuclear ignition in inertial confinement fusion (ICF) is presented in the familiar frame of a Lawson-type criterion. The product of the plasma pressure and confinement time P tau for ICF is cast in terms of measurable parameters and its value is estimated for cryogenic implosions. An overall ignition parameter chi including pressure, confinement time, and temperature is derived to complement the product P tau. A metric for performance assessment should include both chi and P tau. The ignition parameter and the product P tau are compared between inertial and magnetic-confinement fusion. It is found that cryogenic implosions on OMEGA [T. R. Boehly , Opt. Commun. 133, 495 (1997)] have achieved P tau similar to 1.5 atm s comparable to large tokamaks such as the Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] where P tau similar to 1 atm s. Since OMEGA implosions are relatively cold (T similar to 2 keV), their overall ignition parameter chi similar to 0.02-0.03 is similar to 5x lower than in JET (chi similar to 0.13), where the average temperature is about 10 keV. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3380857]