NCSX electrical power systems

The National Compact Stellarator Experiment (NCSX) is being designed to be built in the existing facilities at Princeton Plasma Physics Laboratory (PPPL). The design of the NCSX electrical power system is tailored to suit the available infrastructure and electrical equipment on site. The equipment at PPPL is located primarily in two sites called C-Site and D-Site. D-Site houses the majority of electrical equipment. Most of the equipment being used for the currently operating National Spherical Torus Experiment (NSTX) located in D-Site and the earlier Fusion Experimental devices in C-Site, are proposed to be used with suitable modifications to reflect NCSX needs. The NCSX is proposed to be located in C- Site, based on the available Neutral Beam equipment and a Test Cell to house the device. Thus NSTX and NCSX will share some of the available power supplies. The number of circuits and the location of the NCSX device in the C-Site, drove the major changes in the power system hardware. Only the D-Site power supplies can meet the time response and energy requirements of NCSX. DC power will be transmitted from D-Site to C-Site. The NCSX has a total of nine circuits to be fed from D-Site. Three of the nine circuits are bipolar and the rest are unipolar. Two circuits known as Trim Coils will be fed from the available thyristor power supplies in C-Site. Additional power supplies are available for two more circuits. The hardware needs to be modified to address the requirements of NCSX power loops. The aim is to make the changes in the most cost-effective manner without compromising technical requirements. This paper describes the design changes and addition to the electrical power system components for the NCSX magnet system.