The design of two color interferometer system for the 3-dimensional analysis of plasma density evolution on KSTAR

•A Two Color Interferometer (TCI) system is designed for 3-D measurement of KSTAR.•TCI is consists of 10.6 μm CO2 laser and 0.63 μm HeNe laser with tangential 5 channels.•2 channels are installed in 2016 and 5 channel operation is planned in 2017.

A 5-channel two color interferometer (TCI) system has been designed on KSTAR. TCI system is designed for tangential beam paths, which will combine with two existing interferometer systems of vertical and radial beam paths, so that it will provide 3-dimensional measurement of electron density evolution. TCI system uses wavelengths of 10.6 μm by a CO2 laser and 0.633 μm by a HeNe laser. The system compensates the vibrational noise by using two colors and avoids refraction by short wavelengths. The main purpose of the TCI is to generate routine measurement of the line integrated plasma density for the real time density control on KSTAR. The 5-channels will provide profile data for the density. Time resolution of the system is expected to be 500 kHz or higher in order to measure 3-dimensional density fluctuations for ELMs and other MHD activities including TAE modes. The system is planned to be working on KSTAR 2016 campaign with 1-2 channels.