Japanese and British physicists reported Thursday they had carried out experiments pointing to a new way of achieving nuclear fusion, the elusive goal of cheap, abundant and safe energy. Harnessing this energy has obsessed scientists for more than a quarter century, a period in which oil shocks, the Chernobyl disaster and global warming have driven home the problems of fossil fuels and nuclear fission. But the vision has always been clouded by technical problems. So far, fusion has only been achieved for a maximum of one second in laboratory conditions, and with a disappointingly low energy return. But in research published in Nature, the British science weekly, a 20-member team led by Ryosuke Kodama of Japan’s Osaka University report on an innovation that, they hope, may get round some of the biggest problems. Their approach enhances a technique called inertial confinement fusion (ICF).