Evaluation of the ITER Real-Time Framework for Data Acquisition and Processing from Pulsed Gigasample Digitizers

Plasma diagnostics systems are becoming progressively more advanced. Contemporarily, researchers strive to achieve longer plasma pulses, and therefore, appropriate hardware is required. Analogue-to-Digital Converters are applied for data acquisition in many plasma diagnostic systems. Some diagnostic systems need data acquisition with gigahertz sampling frequency. However, gigasample digitizers working in continuous mode generate an enormous stream of data that requires suitable, high-performance processing systems. This becomes even more complicated and expensive for complex multi-channel systems. Nonetheless, numerous plasma diagnostic systems operate in a pulse mode. Thomson scattering (TS) diagnostics is a good example of a multi-channel system that does not require continuous data acquisition. Taking this into consideration, the authors decided to evaluate the CAEN DT5742 gigasample digitizer as a more cost-effective solution that would utilize the pulsed nature of the TS diagnostic system. The paper presents a complete data acquisition and processing system dedicated for plasma diagnostics based on the ITER real-time framework (RTF). Integration of RTF with real hardware is discussed. The authors of the paper have developed software including RTF function block for the CAEN DT5742 digitizer, example data processing algorithms, data archiving and publishing for plasma control system.