The National Compact Stellarator Experiment (NCSX) is a plasma confinement experiment that was being conducted at the Princeton Plasma Physics Laboratory. First plasma was scheduled to take place in July 2009. It is a variation of the stellarator concept, with a much lower aspect ratio than a typical stellarator. NCSX would have been one of the first fusion experiments to use massively parallel computing to find the optimal shape for the reactor vessel; one of the advantages of correctly-designed stellarators is that the confined plasma is passively stable when a steady magnetic field is applied, whereas tokamaks require an array of active control strategies to stabilize the plasma, even under a constant magnetic field. Up to 12MW of auxiliary heating power would have been available to the NCSX chamber, consisting of 6MW from tangential neutral beam injection, and 6MW from radio-frequency (RF) heating. Up to 3MW of electroncyclotron heating would also have been available in future iterations of the design.
As of May 22, 2008 the NCSX project was canceled by the Department of Energy due to a failure to meet budgetary constraints . The assembly tolerances were very tight and required state of the art use of metrology systems including Laser Tracker and photogrammetry equipment. $50 million of additional funding was needed, spread over the next 3 years, to complete the assembly within tolerance requirements.