Upgraded calibrations of the Thomson system at DIII-D

The DIII-D Thomson system measures electron density (ne) and temperature (Te) with eight pulsed ND:YAG lasers along three paths through the plasma vessel. The components of the Thomson system are absolutely calibrated so the measurements can be combined into a single profile from a normalized plasma radius (ρ) of about 0.1 to the edge of the plasma. A monochromator calibration and opto-electronic calibration measure the detectors’ absolute sensitivity to background and pulsed light. A Rayleigh scattering calibration and transmission calibrations measure the transmission of light to the detectors. The calibration systems are being upgraded to reduce the effect of systematic errors on the temperature and density measurements. The observed systematic errors can be estimated by comparing fits to averaged profiles to the average profiles. The contributions of the systematic uncertainties relative to the statistical uncertainties of the measurement are discussed through simulations and experimental data.