National Nuclear Security Administration (NNSA) Defence Programmes Deputy Administrator Marvin Adams said the breakthrough also had military applications. It would enhance defence capability by testing nuclear weapons without having to carry out explosions and demonstrate the nuclear technology superiority of the US, he said.

Unlike current nuclear energy production that uses fission technology, which splits atoms, fusion does not create dangerous nuclear waste and scientists say that there would be no danger of radioactive leads. The experiment at the NIF on December 5 that demonstrated the fusion capability focused 192 powerful laser beams at a pea-sized container with frozen hydrogen.

The laser beams’ energy was converted into x-rays that squeezed the hydrogen until it imploded releasing energy. LLN said that the 2.05 megajoules (MJ) of energy used to set off the process delivered 3.15 MJ of fusion energy output. There are two competing ways to achieve fusion, one with magnetic energy and the using lasers. Now the laser method has achieved the breakthrough of producing more energy than is used to produce it. Stephane Dujarric, the spokesperson for UN Secretary-General Antonio Guterres said that “it is an extremely important development in the fight against climate change”.

But noting that the application of fusion technology will take time, he added that it should not curtail the current efforts to contain climate change. At the announcement, Prabhakar recalled that as a 19-year-old intern at the LLNL she had worked for three months “on this fun laser” in 1978. She recalled that scientists told her, “We think that if you point enough lasers at a pellet of fuel, we want to see if we can get more energy released from fusion than the amount of energy that the lasers deliver into that palette”. And it has taken decades since to achieve it.