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

The metastable Ne(

The fluorescence excitation spectra of metastable3 P2 Ne atoms in superfluid helium have been studied for the first time. Ne spectral lines show a surprisingly small broadening and shift. We have also studied emission spectra and decay times related to the strongly forbidden N(2D → 4S) transition in the impurity-helium solid phase (IHSP) containing metastable N atoms, N2 molecules and - in some cases - rare gas atoms (Rg = Ne or Kr). We have shown that the central cores of solid He clusters correspond to single metastable N*(2D) atoms or to N*-N2 and N*-Rg pairs as well as to triple N*-N2-Rg and exciton-like N*Rgn complexes, as evidenced by their luminescence spectra