Fast Protection Unit Designed for the Electron Cyclotron Resonance Heating System on J-TEXT

Two types of fast protection units are designed and established to ensure the safe operation of the electron cyclotron resonance heating (ECRH) system on Joint Texas Experimental Tokamak (J-TEXT). One is the overvoltage and overcurrent fast protection unit; and the other is the arc fast protection unit. All of them are used to send protection signals to the control unit for switching off the high-voltage power supplies of the gyrotron when there is a fault. The circuits based on two types of fast protection units are designed and tested. The response time of the overvoltage and overcurrent fast protection circuit is less than 900 ns, and the response time of the arc fast protection circuit is less than 1.2~\mu \text{s} . The test results show that these two fast protection units can fulfill the safe operation requirements of the ECRH system on J-TEXT.