Scientists say they have cleared technical hurdle in fusion research: "In fusion, atomic nuclei are fused together to release energy, as opposed to fission -- the technique used for nuclear power and atomic bombs -- where nuclei are split.

In a fusion reactor, particles are rammed together to form a charged gas called a plasma, contained inside a doughnut-shaped chamber called a tokamak by powerful magnetic coils

A consortium of countries signed a deal last year to build the International Thermonuclear Experimental Reactor (ITER) in southern France as a testbed for an eventual commercial design.

But many experts have been shaking their heads at the many challenges facing the ITER designers. "