Development of polarization interferometer for Thomson scattering diagnostics in JT-60U

Hatae, Takaki; Howard, J.*; Ebizuka, Noboru*; Hirano, Yoichi*; Koguchi, Haruhisa*; Kitamura, Shigeru; Sakuma, Takeshi; Hamano, Takashi

A polarization interferometer based on the Fourier transform spectroscopy for the Thomson scattering diagnostics is being developed to evaluate the validity. At the first stage, a dual channel polarization interferometer utilizing a fixed-thickness birefringent plate is developed, and the target and ranges were 1 keV and 510 m, respectively. The electron temperature is successfully measured by the dual channel polarization interferometer in TPE-RX reversed field pinch machine, for the first time. The temperature of the polarization interferometer nearly agrees with that of the filter polychromator. At the second stage, we are developing a multichannel polarization interferometer employing a Wallaston prism to cover wider range of electron temperature. Interferograms of three kinds of light sources are measured by the multichannel polarization interferometer, and those spectra are reconstructed by Fourier transform. In the measurement of a blackbody radiation source using the multichannel polarization interferometer, both ideal and measured spectra agree within 8%.