Digital coil protection system I/O and data subsystem for NSTX-U

The Digital Coil Protection System (DCPS) for NSTX-U is a system that evaluates operational parameters in real time and prevents physical damage to the reactor and its coils. The system is built upon commercial products: a realtime Linux operating system and analog and digital I/O boards. Signals from various digital and analog sources are captured, conditioned, validated and stored before being passed to a system of parallel algorithms for processing. Incremental data must be recorded during processing for postshot analysis. Additionally, algorithm parameter data must be stored in a fashion that prevents both inadvertent and malicious tampering which could result in exposing the machine to the risk of severe damage. This paper will discuss the object oriented design and implementation used to address these challenges. Details of how real time Linux tools were used to ensure predictable and stable operation will also be discussed.