Preliminary Design of ITER Divertor Langmuir Probe System

The primary aim of the ITER divertor Langmuir probe system is to measure the plasma parameters at the divertor target plates. Saturation ion flux coming from the direct-current biased probe mode is used for advanced machine control, and the swept double-probe mode is recommended to measure electron temperature and density for physics studies. The design of the probe system includes three parts. First, tungsten Langmuir probes are mounted on the side of the target plates for collecting current from plasma, and thermomechanical simulation results show the design of the probe is robust and can survive under harsh working environments. Second, the electronics consists of the power supply, mode switching, and signal conditioning box and is used for driving Langmuir probes in different operation modes to obtain expected plasma information. Third, the functions of instrument and control include publishing configuration; monitoring and control; calibration; data acquisition; communication with the control, data access and communication (CODAC) system; and real-time ion flux measurement at the divertor target. The system design also complies with ITER’s technical practices, standards, and codes.