An anonymous reader quotes a report from Space.com: For several decades now, scientists from around the world have been pursuing a ridiculously ambitious goal: They hope to develop a nuclear fusion reactor that would generate energy in the same manner as the sun and other stars, but down here on Earth. Incorporated into terrestrial power plants, this "star in a jar" technology would essentially provide Earth with limitless clean energy, forever. And according to new reports out of Europe this week, we just took another big step toward making it happen. In a study published in the latest edition of the journal Nature Communications, researchers confirmed that Germany's Wendelstein 7-X (W7-X) fusion energy device is on track and working as planned. The space-age system, known as a stellerator, generated its first batch of hydrogen plasma when it was first fired up earlier this year. The new tests basically give scientists the green light to proceed to the next stage of the process. It works like this: Unlike a traditional fission reactor, which splits atoms of heavy elements to generate energy, a fusion reactor works by fusing the nuclei of lighter atoms into heavier atoms. The process releases massive amounts of energy and produces no radioactive waste. The "fuel" used in a fusion reactor is simple hydrogen, which can be extracted from water. The W7-X device confines the plasma within magnetic fields generated by superconducting coils cooled down to near absolute zero. The plasma -- at temperatures upwards of 80 million degrees Celsius -- never comes into contact with the walls of the containment chamber. Neat trick, that. David Gates, principal research physicist for the advanced projects division of PPPL, leads the agency's collaborative efforts in regard to the W7-X project. In an email exchange from his offices at Princeton, Gates said the latest tests verify that the W7-X magnetic "cage" is working as planned. "This lays the groundwork for the exciting high-performance plasma operations expected in the near future," Gates said.