Signal Transmission Links for the Electron Cyclotron Resonance Heating System on J-TEXT

Electron cyclotron resonance heating (ECRH) is an important auxiliary heating method which is widely used in magnetic confinement fusion. For the ECRH system on J-TEXT, signals should be transmitted to the control system for monitoring and protection and also to the data acquisition system. Considering the high-voltage and harsh electromagnetic interference environment, reliable fiber-optic transmission links are applied. Transmitted by fiber-optic modules, the response time of digital signals can be less than 1~\mu \text{s} . According to the ECRH system requirements, two practical analog fiber-optic transmission links based on the voltage-to-frequency and frequency-to-voltage conversion technology have been designed and developed. With IC AD650, the delay time of most analog signals is less than 100~\mu \text{s} , and with IC VFC110, critical signal transmission delay can be shortened to 5~\mu \text{s} . The test results indicate that the designed signal transmission links for ECRH system on J-TEXT are stable and reliable.