A team of researchers from the Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) has broken the record for the amount of energy produced by a contained fusion reaction, a step closer towards a clean and abundant energy source. The researchers presented their results in a recent paper published in Nature.
Using Inertial Confinement Fusion (ICF), the team caused a deuterium-tritium (DT) fuel pellet to release more energy than it initially absorbed. Energy released from the 2mm diameter DT fuel capsule was an order of magnitude larger than previously recorded.
The paper, entitled Fuel gain exceeding unity in an inertially confined fusion implosion, states that the researchers managed to create the beginning of the chain reaction necessary to turn nuclear fusion into a commercial energy source. This requires the alpha particles emitted after the initial reactions to deposit energy back into the fuel capsule, causing further ignition and a 'run away' reaction.
As reported in the February edition of Electro Optics Magazine, this result should not be confused with the overall requirements for the commercialisation of nuclear fusion energy. The success was that the chain reaction was started, but the energy absorbed by the fuel capsule is not the same as the energy that the facility had to use to induce the reaction.
The ‘indirect drive’ method used by the facility involves a small hollow capsule, known as a hohlraum, to house the pellet. By bombarding the hohlraum with 192 separate laser beams the capsule releases a bath of X-rays. It is these X-rays that the fuel capsule absorbs and emits, not the 1.8MJ of laser energy initially supplied.
In order for nuclear fusion to be a viable commercial energy source, the energy emitted would have to exceed the energy put into the reaction, which is the NIF's, and other nuclear fusion research facilities', ultimate goal.