A wide range real-time synchronous demodulation system for the dispersion interferometer on HL-2M

Tongyu Wu; Wei Zhang; Zejie Yin

doi:10.1063/1.4991318

A wide range real-time synchronous demodulation system for the dispersion interferometer on HL-2M

Rev Sci Instrum. 2017 Sep;88(9):093501. doi: 10.1063/1.4991318.

Authors

Tongyu Wu¹, Wei Zhang¹, Zejie Yin¹

Affiliation

¹ State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026, People's Republic of China.

PMID: 28964172
DOI: 10.1063/1.4991318

Abstract

A real-time synchronous demodulation system has been developed for the dispersion interferometer on a HL-2M tokamak. The system is based on the phase extraction method which uses a ratio of modulation amplitudes. A high-performance field programmable gate array with pipeline process capabilities is used to realize the real time synchronous demodulation algorithm. A fringe jump correction algorithm is applied to follow the fast density changes of the plasma. By using the Peripheral Component Interconnect Express protocol, the electronics can perform real-time density feedback with a temporal resolution of 100 ns. Some experimental results presented show that the electronics can obtain a wide measurement range of 2.28 × 10²² m^-2 with high precision.