NSTX TF joint failure and re-design

The toroidal field (TF) coil of the National Spherical Torus Experiment (NSTX) suffered a failure on February 14, 2003, after approximately 3 years of service and 7200 pulses. The failure occurred at an electrical joint connecting one of the radial flags to the inner leg bundle. Damage was extensive such that the coil could not be repaired. Analysis of the failure revealed structural design problems which have been addressed in the re-design effort described herein. Construction of a new TF coil is now underway.