Optimization of the HCN interferometer on J-TEXT tokamak

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 x 10(18) m(3) to 2 x 10(17) m(3) and the sawtooth oscillation has also been measured by the HCN interferometer on J-TEXT after optimizations.