Z Machine MagLIF Fusion also making progress

Researchers at Sandia National Laboratories in Albuquerque, New Mexico, using the lab’s Z machine, a colossal electric pulse generator capable of producing currents of tens of millions of amperes, say they have detected significant numbers of neutrons—byproducts of fusion reactions—coming from the experiment.

For enough reactions to take place, the hydrogen nuclei must collide at velocities of up to 1000 kilometers per second (km/s), and that requires heating them to more than 50 million degrees Celsius.

Sandia’s technique is one of several that fall into the middle ground between the extremes of laser fusion and the magnetically confined fusion of tokamaks. It crushes fuel in a fast pulse, as in laser fusion, but not as fast and not to such high density. Known as magnetized liner inertial fusion (MagLIF), the approach involves putting some fusion fuel (a gas of the hydrogen isotope deuterium) inside a tiny metal can 5 millimeters across and 7.5 mm tall. Researchers then use the Z machine to pass a huge current pulse of 19 million amps, lasting just 100 nanoseconds, through the can from top to bottom. This creates a powerful magnetic field that crushes the can inward at a speed of 70 km per second.

Crushing the plasma also boosts the constraining magnetic field, from about 10 tesla to 10,000 tesla.

They heated the plasma to about 35 million degrees Celsius and detected about 2 trillion neutrons coming from each shot. (One reaction of fusing two deuteriums produces helium-3 and a neutron.) Although the result shows that a substantial number of reactions is taking place—100 times as many as the team achieved a year ago—the group will need to produce 10,000 times as many to achieve breakeven.

A schematic representation of the three critical components of the MagLIF concept. An axial current creates a Jz×BΘ force that is used to implode a gas-filled, premagnetized, cylindrical target. Near the start of the implosion, the fuel is heated by the laser. The liner compresses and further heats the fuel to fusion-relevant conditions at stagnation.

Physical Review Letters – Experimental Demonstration of Fusion-Relevant Conditions in Magnetized Liner Inertial Fusion

Read more »