Initial operation and data processing on a system for real-time evaluation of Thomson scattering signals on the Large Helical Device

TL;DR

This paper reports the initial implementation and data processing of a real-time Thomson scattering analysis system on the Large Helical Device, demonstrating successful operation and data collection during plasma discharges.

Contribution

It adapts a previously developed real-time analysis system for NSTX-U to the LHD, enabling real-time electron temperature and density measurements during plasma discharges.

Findings

System successfully recorded signals at 30 Hz during initial run.

Data processing code was adapted to enhance temperature calculation accuracy.

System operated within its rated capacity, demonstrating feasibility for real-time plasma diagnostics.

Abstract

A scalable system for real-time analysis of electron temperature and density based on signals from the Thomson scattering diagnostic, 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. During its initial operation run, 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.