Shortly after overhaul, malfunction leaves Princeton fusion reactor down for a year

    NSTX-U facility (Elle Starkman/PPPL Office of Communications)

    NSTX-U facility (Elle Starkman/PPPL Office of Communications)

    An experimental fusion reactor in Princeton is down for a year after malfunctioning even though it returned to operation last year following a major overhaul.  

    The facility is funded by the Department of Energy and managed by Princeton University.

    The outage means there is just one other such research station operating in the U.S., in California.

    The reactor, called the National Spherical Torus Experiment-Upgrade (NSTX-U), was established to develop fusion energy as a sustainable energy alternative. Fusion energy is produced when hydrogen is heated to millions of degrees, becomes charged, and the atoms within the plasma, confined by magnets, fuse. When fusion occurs, the reaction releases energy. It’s the same process that powers the sun.

    The hope is that energy can be harnessed to one day power homes and businesses.

    The Princeton reactor specifically is testing a different configuration of the plasma to see if it could lead to smaller, more economic fusion plants.

    The facility just underwent a $94 million, multi-year upgrade.

    Head of Science Education at the Princeton Plasma Physics Laboratory, Andrew Zwicker, said the team is still trying to figure out what exactly went wrong before they make new parts. “The coil that’s used to help cool the magnet failed. When we were investigating why that failed, we then found an internal problem with the coil itself. When we took that apart we found another cooling coil, not related, had some damage, and we had not even used that one yet. At that point we said we need to be very meticulous here, understand exactly what’s going on,” Zwicker said.   

    A write-up in Nature suggested that the failure could have been prevented, but Zwicker says they are still getting to the bottom of how it happened.

    Director of the Princeton lab, Stewart Prager resigned shortly after the failure. Zwicker said Prager had been wanting to step down for some time, and a search for a new director is underway.

    Zwicker said the current budget should cover the year of downtime and a new coil, but it’s unclear how much the fix will actually cost.      

    Meanwhile, researchers are working with data obtained before the breakdown, and collaborating with other fusion labs around the world. 

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