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--By John Greenwald

A promising experiment that encloses hot, magnetically confined plasma in a full wall of liquid lithium is undergoing a $2 million upgrade at the US Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL). Engineers are installing a powerful neutral beam injector in the laboratory's Lithium Tokamak Experiment (), an innovative device used to test the liquid metal as a first wall that enhances plasma performance. The first wall material faces the plasma.

 "This will bring us one step closer to demonstrating this particular approach to fusion," said Dick Majeski, principal investigator of the LTX. The experiment is a collaborative effort that includes researchers from Oak Ridge National Laboratory, UCLA, the University of Tennessee, Knoxville, and Princeton University, as well as PPPL. Funding comes from the DOE Office of Science. 

The neutral beam injector, a Russian-built device on loan from the Tri Alpha fusion firm in California, will shoot energetic beams into the small spherical tokamak to fuel the core of the plasma and increase its temperature and density—key factors in fusion reactions. "The beams will maintain the density and raise the temperature to a more fusion-relevant level," said Philip Efthimion, PPPL head of the Plasma Science and Technology Department that includes the LTX.

The experiment recently became the first device in the world to produce flat temperatures in a magnetically confined plasma. Such flatness reduces the loss of heat from the plasma that can halt fusion reactions.  The LTX also has provided the first experimental evidence that coating a large area of walls with liquid lithium can produce high-performance plasmas.

However, without fuelling from the neutral beam the density of an LTX plasma tends to drop off fast. The beam upgrade will keep the density from dropping, and test whether the liquid lithium coating can continue to maintain flat temperatures in much hotter plasmas.

Read the full story on the PPPL .

If new energy sources offer cheap, plentiful power to everyone, how will the planet cope? FutureProofing examines a new method of power generation promising clean, limitless power for everyone. Can it work, what are the consequences, and is there a viable alternative?

Fusion has long-promised cheap, clean and limitless power, but over half a century of effort this technology has still not delivered an operational power plant. Now hopes are high that a vast project in the south of France will finally crack the problems and deliver a working model that can be replicated around the world. FutureProofing presenters Timandra Harkness and Leo Johnson travel to Provence to find out what the prospects are for a scheme costing upwards of £10 billion which could transform the energy supply for us all and with it global geopolitics and the environment for centuries to come.

The program explores what viable alternatives there could be to generate power at the same scale for billions of people across the world, and whether such an alternative is a better route to achieving the goal of cheap, plentiful and clean energy for the future. (Producer: Jonathan Brunert)

Follow this link to the 42-minute .