Development of polarization interferometer for Thomson Scattering Diagnostics in JT-60U

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 Te and ne ranges were 5x10 18 m -3 , 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 a 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 monochromatic light sources are measured by the multichannel polarization interferometer, and those spectra are reconstructed by Fourier transform.