Tangential Thomson scattering diagnostic for the KSTAR tokamak

Abstract

A Thomson scattering diagnostic system has been developed for electron density and temperature measurements in KSTAR. The KSTAR Thomson scattering diagnostic system has a 90 degree scattering configuration with the tangential laser-beam input optics and the horizontal collection optics. In the KSTAR 4th campaign, measuring spatial points of the Thomson scattering system was 5 ea for core with 120 mm, 60 mm spacing and 12 ea for edge with 20 mm, 10 mm spacing, respectively. For KSTAR Thomson scattering system, we used the commercial 10 Hz, 2 J, 1064 nm Nd:YAG laser that was installed through the Korea-Japan collaboration. To get the Thomson scattering spectrum, we equipped the core and edge polychromators. And the edge polychromators were developed by Korea-Japan collaboration and manufactured by NIFS, Japan. The measurable range of core polychromator was 500 eV to 20 KeV and edge was 10 eV to 1.8 KeV. To evaluate the electron density and electron temperature, we measure the Rayleigh scattering signals by using polychromator's 1064 nm filter channels and relative calibration by using a tungsten (W) lamp with monochromator system. The measurement result of Rayleigh scattering signal with nitrogen (N2) gas was clearly proportional to the nitrogen density rate. We use the QDC(Charge-to-Digital Conversion) system with signal amplifier ( × 4) to get Thomson scattering signal. In this paper, we report the first result of electron temperature and density by using the tangential Thomson scattering system on KSTAR 4th campaign.