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

Magnetic shielding of neutral beam sources in mirror fusion test facility

The magnetic shields of the Mirror Fusion Test Facility neutral beam sources must keep the inner magnetic field below 0.15 mT inside an unsymmetrical ambient magnetic field of 0.05 to 1.5 T. Numerical computations and 1/10th-scale experiments were used to arrive at a three-layer shield design consisting of two thin nickel-iron alloy shells inside a thick mild steel shell. A 1/10th-scale prototype test confirmed the final design