The non-functioning US National Spherical Torus Experiment (NSTX) at Princeton Plasma Physics Laboratory (PPPL) undergo repairs in April according to reports. The NSTX tokamak based reactor was taken offline in 2016 due to a magnetic coil shorting problem. A single coil problem was introduced after a $94 million upgrade that started in 2011. In the case of the NSTX if one of the coils shorts the whole reactor has to be taken apart to be fixed. NTSX reactor, which is the DOE’s big tokamak, has been offline since 2011 leaving PPPL’s researchers extremely frustrated. It will take $199 million to repair NTSX. The hope is that the NSTX reactor will be back online during the summer 2021.
The link below has a great article with a brief history of the NSTX, PPPL and it’s new leadership in the form of Steven Cowley.