Other major spherical tokamak experiments include the START and MAST at Culham in the UK.

If successful it was to be followed by similar devices, eventually including a demonstration power reactor (e.g. ITER), burning deuterium-tritium fuel.

Design challenges include the toroidal and poloidal field coils, vacuum vessels and plasma-facing components.

NSTX's attractiveness may be further enhanced by its ability to trap a high "bootstrap" electric current.

The origin of this failure is partly attributed to a non-compliance of the chilled copper winding, the manufacture of which had been sub-contracted.

After a diagnostic phase requiring the complete dismantling of the device and coils, evaluation of the design, and a redesign of major components including the six inner poloidal coils,[5][6] a restarting plan was adopted in March 2018, with reactivation scheduled for the end of 2020,[7] though this was later pushed back to 2022.