As with the inertial approach, fusion is initiated by rapidly squeezing the target to greatly increase fuel density and temperature.
Although the resulting density is far lower than in ICF, it is thought that the combination of longer confinement times and better heat retention will let MTF operate, yet be easier to build.
Fusion occurs when two ions collide at high energy, allowing the strong force to overcome the electrostatic repulsion at a short distance.
For fusion to occur in bulk plasma, it must be heated to tens of millions of degrees and compressed at high pressures, for a sufficient amount of time.
Magnetic fusion works to heat a dilute plasma (1014 ions per cm3) to high temperatures, around 20 keV (~200 million C).
To make a practical reactor at these temperatures, the fuel must be confined for long periods of time, on the order of 1 second.
The ITER tokamak design is currently being built to test the magnetic approach with pulse lengths up to 20 minutes.
As of 2018[update], both of these methods of nuclear fusion are nearing net energy (Q>1) levels after many decades of research, but remain far from practical energy-producing devices.
MTF employs a magnetic field that is created before compression that confines and insulates fuel so less energy is lost.
The MTF concept is based on having this dwell time be long enough for the fusion processes to take place.
The cost and complexity of these lasers, termed "drivers", is so great that traditional ICF methods remain impractical for commercial energy production.
The densities, temperatures and confinement times needed by MTF are well within the current state of the art and have been repeatedly demonstrated.
[3] It uses four high-voltage (up to 100 kV) capacitor banks storing up to 1 MJ of energy to drive a 1.5 MA current in one-turn magnetic-field coils that surround a 10 cm diameter quartz tube.
[6] In its current form as a plasma generator, FRX-L has demonstrated densities between (2 and 4)×1016 cm−3, temperatures of 100 to 250 eV, magnetic fields of 2.5 T and lifetimes of 10 to 15 μs.
Shiva Star delivers about 1.5 MJ into the kinetic energy of the 1 mm thick aluminum liner, which collapses cylindrically at about 5 km/s.
[9] The power released in the larger shots, in the range of MJ, needs a period of resetting the equipment on the order of a week.
To produce power effectively, the density must be increased to a working level and then held there long enough for most of the fuel mass to undergo fusion.
Mixing of the metal with the fusion fuel would "quench" the reaction (a problem that occurs in MCF systems when plasma touches the vessel wall).
In typical MCF schemes, neutrons are intended to be captured in a lithium shell to generate more tritium to feed in as fuel, further complicating the overall arrangement.