Initial operation of a real-time Thomson scattering evaluation system on the Large Helical Device

A scalable system for real-time analysis of electron temperature and density based on Thomson scattering signals, initially developed for and installed on the NSTX-U experiment, was recently adapted for the Large Helical Device (LHD) and operated for the first time during plasma discharges. The system consists of fast digitizers and a server with multiple parallel-operating CPUs, each of which infers temperature and density values for a spatial point in the LHD plasma. During its initial operation, it routinely recorded and processed signals for four spatial points at the laser repetition rate of 30 Hz, well within the system's rated capability for 60 Hz. We present examples of data collected from this initial run and describe subsequent adaptations to the analysis code to improve the fidelity of the temperature calculations.