2007 Volume 2 Pages S1106
We have carried out absolute calibrations of the LHD YAG Thomson scattering system by using Raman scattering and Rayleigh scattering in order to verify the applicability of Rayleigh calibration in the LHD Thomson scattering, and make a comparative study of Raman and Rayleigh calibrations. In the LHD Thomson scattering device, Rayleigh calibration is expected to give more reliable calibration factors. For the Rayleigh calibration, additional Rayleigh channel was installed into 20 polychromators. The other 124 polychromators without Rayleigh channel were calibrated by only Raman scattering. In the Raman calibration, pure gaseous nitrogen was introduced into the LHD vacuum vessel whereas the Rayleigh calibration was made by using air as target gas. The calibration factors obtained from the Raman and Rayleigh calibrations show good agreements. Uncertainties in the calibration factors obtained from the Raman and Rayleigh calibrations are discussed.
