Speaker
Dr
Jinlin Xie
(University of Science and Technology of China)
Description
A solid-state source based terahertz (0.65 THz) interferometer diagnostic system has been installed on a recently built Reversed Field Pinch device, Keda Torus eXperiment (KTX). The multichannel interferometer on KTX utilizes two independent solid-state diode sources based frequency multiplier (X48), which provid an Intermediate Frequency (IF) with wide range. It is proved that the solid-state sources have an inborn advantage of stable IF frequency. The IF frequency gradually reaches pre-described IF frequency within several minutes and keeps almost constant for several hours without any techniques of active frequency stabilization. Compared with the traditional FIR laser used in the multi-channel interferometer system, the solid-state sources provide much less output power, approximately 2 mW. The planar-diode mixers optimized for high sensitivity, ∼750 mV/mW, are used in the heterodyne detection system, which assists the realization of the seven channels interferometer on KTX with a low phase noise.
A sensitivity of $n_{\mathrm{e}_\mathrm{min}} = 2 \times 10^{17}$ m$^{−2}$ and a temporal resolution of 0.2 μs have been successfully achieved. The evolution of density distribution in the small cross section of KTX has been determined. It should be addressed that the whole interferometer system is placed on a compact and lightweight support platform. To eliminate the electromagnetic disturbances in the harsh environment of a fusion device, nonmetallic epoxy resin has been selected as main material for the support platform and the commercially available metal optical mounts are replaced with non-metallic components. The phase shift caused by the vibration has been greatly reduced to the level of background noise. The techniques presented here provide a new solution for future interferometer system with turn-key operation, compact size and easy maintenance. The vibration-isolated stable support platform is useful not only for the interferometer system, but also for future Thomson scattering diagnostics on the KTX.
Primary author
Dr
Jinlin Xie
(University of Science and Technology of China)
Co-authors
Dr
Adi Liu
(University of Science and Technology of China)
Dr
Hong Li
(University of Science and Technology of China)
Prof.
Jian Zheng
(University of Science and Technology of China)
Dr
Peng Yuan
(University of Science and Technology of China)
Dr
Tao Lan
(University of Science and Technology of China)
Prof.
Wandong Liu
(University of Science and Technology of China)
Prof.
Weixing Ding
(University of Science and Technology of China)
Dr
Wenzhe Mao
(University of Science and Technology of China)
