One of the biggest obstacles to making fusion power practical — and realizing its promise of virtually limitless and relatively clean energy — has been that computer models have been unable to predict how the hot, electrically charged gas inside a fusion reactor behaves under the intense heat and pressure required to make atoms stick together.
The key to making fusion work — that is, getting atoms of a heavy form of hydrogen called deuterium to stick together to form helium, releasing a huge amount of energy in the process — is to maintain a sufficiently high temperature and pressure to enable the atoms overcome their resistance to each other.
Ref: Multi-scale gyrokinetic simulation of tokamak plasmas: enhanced heat loss due to cross-scale coupling of plasma turbulence. Nuclear Fusion (17 December 2015) | DOI: 10.1088/0029-5515/56/1/014004 | (PDF) Open Access
Fusion ignition, the point at which a nuclear reaction becomes self-sustaining, is one of the great hopes for a new generation of clean, cheap energy generation. But while the reactions have been seen in the cores of thermonuclear weapons, it has yet to be achieved in a controlled manner in a reactor.
Ref: Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets. Nature Physics (11 January 2016) | DOI: 10.1038/nphys3614