Raman calibration of the LHD YAG Thomson scattering for electron-density measurements

We have calibrated the LHD yttrium aluminum garnet (YAG) Thomson scattering system by using anti-Stokes rotational Raman scattering from air for the measurements of absolute electron-density profiles of LHD plasmas. The air Raman calibration was carried out at near atmospheric pressure and room temperature. Total uncertainty in measured electron densities is estimated to be ±15% or less. Electron densities obtained with the calibrated YAG Thomson scattering show good agreements with those measured by the LHD millimeter-wave interferometer