The NIF missed its goal of achieving ignition by 2012 scientists have spent the years since fine-tuning the facility and introducing optimized targets into the reaction chamber. Construction began in 1997 and ended more than a decade later, several years behind schedule and at least $2.4 billion over budget. Nobody said it would be easy, but building the NIF proved to be a more complex endeavour than officials originally thought. Why has it taken so long to (nearly) achieve ignition? Preliminary results from the experiment on 8 August indicate that fusion reactions generated a record-shattering 70% of the power that went into the experiment - nearly achieving ignition. The goal is to unleash a cascade of particles that leads to more fusion and more particles, thus creating a sustained fusion reaction by definition, ‘ignition’ occurs when the fusion reaction generates more energy than it consumes. The beams hit the target - a gold cylinder - with around 1.9 megajoules of energy in less than 4 billionths of a second, creating temperatures and pressures seen only in stars and thermonuclear bombs.įaced with this pulse power, the cylinder, which holds a frozen pellet of deuterium and tritium, collapses as the hydrogen isotopes at the pellet’s core heat up, fuse and generate helium nuclei, neutrons and electromagnetic radiation. Ten storeys high and spanning the area of three American football fields, the NIF houses an array of optics and mirrors that amplify and split an initial pulse of photons into 192 ultraviolet laser beams, ultimately focusing them on a target that is smaller than a pencil eraser. Here Nature looks at the NIF’s long journey, what the advance means for the energy department’s stewardship programme and what lies ahead. “Where can we go? How much further can we go?” “That’s really the scientific question for us at the moment,” says Mark Herrmann, Livermore’s deputy director for fundamental weapons physics. With this month’s laser-fusion breakthrough, scientists are cautiously optimistic that the NIF might live up to its promise, helping physicists to better understand the initiation of nuclear fusion - and thus the detonation of nuclear weapons. After the United States banned underground nuclear testing at the end of the cold war in 1992, the energy department proposed the NIF as part of a larger science-based Stockpile Stewardship Program, designed to verify the reliability of the country’s nuclear weapons without detonating any of them. Housed at Lawrence Livermore National Laboratory in California, the US$3.5-billion facility wasn’t designed to serve as a power-plant prototype, however, but rather to probe fusion reactions at the heart of thermonuclear weapons. UK hatches plan to build world's first fusion power plant
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