In a statement, NIF boffins said that on July 30, they repeated the ignition process and got the motor ticking over. They did not rev it up.

The improved result at NIF, coming "only eight months" after the initial breakthrough, was a further sign that the pace of progress was increasing, said one of the people with knowledge of the results.

The result was that they managed to get more power out than they put in. Which is an encouraging sign for those who want fusion.  

Although many scientists believe fusion power stations are still decades away, the technology's potential is hard to ignore. Fusion reactions emit no carbon, produce no long-lived radioactive waste and a small cup of hydrogen fuel could power a house for hundreds of years.