On Tuesday, a joint press release from the US Department of Energy (DOE) and the department’s National Nuclear Security Administration announced that scientists at the National Ignition Facility (NIF) have achieved a controlled nuclear fusion reaction which resulted in a net energy gain. Data from the facility show that 2.05 megajoules (Mj) of input energy—just under 0.6 kilowatt hours—was used to produce 3.15 Mj of output fusion energy.
To produce the results, nuclear physicists at the NIF used 192 spherically arranged lasers aimed at a half-centimeter target vessel containing deuterium and tritium, two heavy variants of the element hydrogen. An extremely brief and powerful pulse of light from the lasers is channeled by the target to produce a symmetrical explosion about the inner hydrogen fuel, imploding and heating it to the extreme conditions where nuclear fusion takes place.
This process, of “burning” hydrogen into helium, powers stars like our Sun over billions of years, but the NIF produces fusion conditions for only 100 trillionths of a second: it reaches temperatures and pressures 10 times higher than those at the center of the Sun to fuse a significant amount of its fuel during that instant, forcing an implosion of the material that ignites the material and starts nuclear fusion, the process through which the Sun and all stars shine.
This process, of “burning” hydrogen into helium, powers stars like our Sun over billions of years, but the NIF produces fusion conditions for only 100 trillionths of a second: it reaches temperatures and pressures 10 times higher than those at the center of the Sun to fuse a significant amount of its fuel during that instant, forcing an implosion of the material that ignites the material and starts nuclear fusion, the process through which the Sun and all stars shine.
The achievement is what is known as scientific breakeven, when the energy produced by the implosion is equal to or greater than the energy transferred to the capsule.
The announcement marks one of the major milestones since the NIF was established in 1997. It was developed as an arm of the Lawrence Livermore National Laboratory to study a method of achieving nuclear fusion, known as inertial confinement fusion. Construction was completed in 2009 and NIF has been performing experiments ever since, leading up to this week’s results.
One of the major difficulties of inertial confinement fusion is that the lasers must hit the target in an exactly spherically symmetrical pattern, otherwise the precise implosion needed to produce fusion either will not occur or will only produce small amounts of energy. As recently as 2018, the NIF was only capable of producing 54 kilojoules of energy, 58 times less than the most recent results.
The announcement marks one of the major milestones since the NIF was established in 1997. It was developed as an arm of the Lawrence Livermore National Laboratory to study a method of achieving nuclear fusion, known as inertial confinement fusion. Construction was completed in 2009 and NIF has been performing experiments ever since, leading up to this week’s results.
One of the major difficulties of inertial confinement fusion is that the lasers must hit the target in an exactly spherically symmetrical pattern, otherwise the precise implosion needed to produce fusion either will not occur or will only produce small amounts of energy. As recently as 2018, the NIF was only capable of producing 54 kilojoules of energy, 58 times less than the most recent results.
A major breakthrough was achieved last year when the scientists developed new techniques to more fully master the symmetries and asymmetries of the system, resulting in an energy yield 25 times greater than the results from 2018. While they at the time had yet to achieve scientific breakeven, the researchers reached 70 percent of that goal. The announcement Tuesday is a further refinement of what was developed last year.
Full report:
Comments
Post a Comment