Development of the real-time Thomson scattering diagnostic for NSTX-U

In preparation for NSTX-U returning to operations in 2026 a number of improvements have been made to the 42 point Thomson scattering system that ran during the last operation of NSTX-U. A new data acquisition system has been installed featuring 16 14-bit Struck digitizer cards that each collect 16 channels at 250 MHz. This Struck system has already been installed by the Princeton Plasma Physics Laboratory (PPPL) team on the W-7X, ST-40 and SMART tokamaks. The PPPL team have developed an algorithm to provide real-time analysis of the electron density and temperature profiles on W-7X and ST-40. This algorithm will be implemented on the existing spatial channels during the NSTX-U restart to improve real-time plasma control with integration into the plasma control system (PCS). The improved temporal resolution of the Struck system will allow a pedestal fitting algorithm to be used to produce automated pedestal fits for high performance plasmas on NSTX-U. This will build on existing work carried out on MAST-U to enhance the database of pedestal data for spherical tokamaks.