Engineering overview of the National Spherical Torus Experiment (NSTX)

The NSTX project will provide a national facility for the study of plasma confinement, heating, and current drive in a low aspect ratio, spherical torus (ST) configuration, the ST configuration is an alternate confinement concept which is characterized by high /spl beta/, high elongation, high bootstrap fraction, and low B/sub T/ compared to conventional tokamaks, NSTX is the next step ST experiment following smaller experiments such as the PPPL CDX-U (Current Drive Experiment, Upgrade), the START (Small Tight Aspect Ratio Tokamak) at Culham, and the HIT (Helicity Injected Tokamak) at University of Washington, and is similar in scale to the MAST (Meg-Amp Spherical Tokamak) machine now under construction at Culham. This paper provides a description of the mission and gives an overview of the engineering features of the design of the machine and facility and discusses some of the key design solutions.