The Stress Analysis of PF1A Lower Terminals, Leads, and Bus Bars for NSTX-U

Both PF1A upper coils and lower coils experienced difficult situations during the National Spherical Torus Experiment–Upgrade (NSTX-U) machine operations in 2016. There are huge up-down electromagnetic forces on PF1A terminals, coil leads, and bus bars. Therefore, further analysis and additional reinforcement supports are needed to reduce the stress on the coil terminals and leads. Structural, thermal, and electromagnetic analyses of the three-dimensional PF1A lower bus bar and coil lead model have been performed using imported electromagnetic loads with the worst cases of 96 scenarios through the global Biot-Savart stick model. The reinforcement blocks for the PF1A lower coil leads and flags and two clamps were analyzed and installed for field testing. The coil leads and bus bars used in the field testing were qualified for the normal NSTX-U operating loads allowing similar reinforcement details to be used in the real NSTX-U machine.