National Spherical Torus Experiment (NSTX) construction, commissioning, and initial operations

The NSTX is a new 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 magnetic confinement concept which is characterized by high beta (ratio plasma pressure to magnetic field pressure) and low toroidal field compared to conventional tokamaks, and could provide a pathway to the realization of a practical fusion power source. Engineering design began in October 1995. Installation of the torus in the test cell began in October 1998. First plasma was achieved in February 1999. Following this event, with the completion of the installation of the internal hardware and RF antenna over the summer of 1999, the construction project has been declared complete, and the machine has been restarted. Operation of the machine, and production of plasma, has been quite reliable, and the experimental campaign has now begun. This paper reports on highlights of the construction, commissioning, and initial operations.