Design of the CRAFT LHCD Power Measurement System

The CRAFT lower hybrid current drive (LHCD) power measurement system was designed to obtain power data of the LHCD system, diagnose and protect the system operation, and provide basic data for physical experimental analysis. The hardware architecture of the system includes transmission lines, directional couplers, attenuators, detectors, isolation amplifier cards, PXI (PCI extensions for Instrumentation) data acquisition card and embedded computer. The software development was based on the QT integrated development environment and MSVC (Microsoft Visual C++) compiler, which encompassed modules for detector management, transmission line management, data acquisition and processing for the acquisition card, and curve display, among others. Performance tests were conducted on two key components, namely the detector and isolation amplifier board. Meanwhile, simulation test was carried out on the overall system. The test results indicate that the entire system performance meets the design goals, with a high level of system reliability and subsequent maintenance and debugging.