Chosen solutions to the engineering challenges of the National Spherical Torus Experiment (NSTX) magnet

NSTX is one of the largest of a new class of magnetic plasma research devices known as spherical tori (ST). The plasma in a ST is characterized by its almost spherical shape with a slender open cylindrical region through its vertical axis. The so-called "center stack" is located in this region. It contains magnetic windings to confine the plasma, induce the plasma current, and shape the plasma. This paper describes the engineering challenges of designing the center stack magnets to meet their operational requirements within this constrained space.