Digital Coil Protection System (DCPS) algorithms for the NSTX centerstack upgrade

A significant upgrade is planned for the National Spherical Torus eXperiment (NSTX) in which plasma current and confining magnetic field intensities will nearly double while plasma duration will more than double. Changes will include replacing the existing centerstack with a new one containing a thicker TF inner Leg, a new OH solenoid coil, and an expansion to six of the complement of PF1 coils controlling plasma divertor shape. Other coils will remain in service with hardware modifications as needed for their approximately three-fold increases in magnetic forces.