DIII-D Thomson scattering diagnostic data acquisition, processing, and analysis software

Abstract

One of the diagnostic systems critical to the success of the DIII-D tokamak experiment is the Thomson scattering diagnostic. This diagnostic is unique in that it measures local electron temperature and density: (1) at multiple locations within the tokamak plasma; and (2) at different times throughout the plasma duration. Thomson "raw" data are digitized signals of scattered light, measured at different times and locations, from the laser beam paths fired into the plasma. Real-time acquisition of this data is performed by specialized hardware. Once obtained, the raw data are processed into meaningful temperature and density values which can be analyzed for measurement quality. This paper provides an overview of the entire Thomson scattering diagnostic software and focuses on the data acquisition, processing, and analysis software implementation. The software falls into three general categories: 1. Set-up and Control: Initializes and controls all Thomson hardware and software, sychronizes with other DIII-D computers, and invokes other Thomson software as appropriate. 2. Data Acquisition and Processing: Obtains raw measured data from memory and processes it into temperature and density values. 3. Analysis: Provides a graphical user interface in which to perform analysis and sophisticated plotting of analysis parameters.