Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Electromagnetic dissociation of B-8 and the rate of the Be-7(p, gamma)B-8 reaction in the Sun

In an effort to better determine the Be-7(p, gamma)B-8 reaction rate, we have performed inclusive and exclusive measurements of the Coulomb dissociation of B-8. The former was a study of longitudinal momentum distributions of Be-7 fragments emitted in the Coulomb breakup of intermediate energy B-8 beams on Pb and Ag targets. Analysis of these data yielded the E2 contribution to the breakup cross section. In the exclusive measurement. we determined the cross section for the Coulomb breakup of B-8 on Pb at low relative energies in order to infer the astrophysical S factor for the Be-7(p, gamma)B-8 reaction. Interpreting the measurements with first-order perturbation theory, we obtained S-E2/S-E1 = 4.7(-1.3)(+2.0) x 10(-4) at E-rel = 0.6 MeV, and S-17(0) =17.8(-1.2)(+1.4) eV b. Semiclassical first-order perturbation theory and fully quantum mechanical continuum-discretized coupled channels analyses yield nearly identical results for the El strength relevant to solar neutrino flux calculations, suggesting that theoretical reaction mechanism uncertainties need not limit the precision of Coulomb breakup determinations of the Be-7(p, gamma)B-8 S factor. A recommended value of S-17(0) based on a weighted average of this and other measurements is presented