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 μs. According to the ECRH system requirements, two practical analog fiberoptic 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 μs, and with IC VFC110, critical signal transmission delay can be shortened to 5 μs. The test results indicate that the designed signal transmission links for ECRH system on J-TEXT are stable and reliable.