Optimization of the HCN interferometer on J-TEXT tokamak

摘要

Recently, the HCN interferometer on J-TEXT has been optimized in many aspects. Firstly, the output power of laser source is more stable after using a new designed movable mirror frame and upgrading the oil thermostatic system. Secondly, the electromagnetic interferences have been eliminated by designing a shielding system. Additionally, the signal-to-noise ratio of intermediate frequency (IF) signal has been increased more than five times by improving the detector circuit. The density resolution has been increased from 1±10~(18) m~(-3) to 2±10~(17) m~(-3) and the sawtooth oscillation has also been measured by the HCN interferometer on J- TEXT after optimizations.