Development and preliminary experimental results of a high-temporal-resolution terahertz solid-source interferometer on EAST

A vertical viewing 0.65 THz Solid-state Source Interferometer (SSI) has been installed for line-integrated density measurements on Experimental Advanced Superconducting Tokamak (EAST) . The SSI utilizes two independent solid-state diode sources with 2 mW output power and a base frequency multiplier, which provides a wide range of Intermediate Frequencies (IF) . The high time resolution of 0.1 μs at a 10 MHz IF has been successfully achieved. The IF signal remains almost constant for several hours without any active frequency stabilization. A sensitivity in the integrated density of 0.77× 1016 m−2 has been obtained. The density measurement has been implemented with IF ~ 0.85 MHz, in a plasma with Ip=600 kA and PLHW=2.1 MW on EAST . The line-averaged density, 3.5× 1019 m−3, measured by the SSI shows good agreement with the results measured by the HCN interferometer system and the POlarimeter-INTerferometer (POINT) system in the same discharge.