Control, Interlock, Acquisition and Data Retrieval Systems for the Negative Ion Source NIO1

The NIO1 (Negative Ion Optimization, phase 1) experiment is a versatile test bench operated by Consorzio RFX and INFN in the framework of the activities aimed at the enhancement of negative ion sources for production of large ion beams for plasma heating in nuclear fusion devices and accelerator applications. The nominal beam current of 135mA at -60kV is divided into 9 beamlets, with multi-aperture extraction electrodes. The plasma is continuously sustained by a 2MHz radiofrequency power supply, with a standard matching box. A High Voltage Deck (HVD) is placed inside the lead shielding surrounding NIO1 and is fed by an insulation transformer installed in a nearby box. It contains the radiofrequency generator, the gas control, electronics and power supplies for the ion source. A closed-circuit water cooling system was installed for the whole system, with a branch towards the HVD. The present contribution describes the control, interlock, acquisition and data retrieval systems for NIO1. Control and data acquisition system implementation require versatility and flexibility for an experiment such as NIO1; for example, new hardware components (e.g. Raspberry PI board, Arduino board, homemade hardware acquisition board) and different types of serial communication (RS232, GPIB, Ethernet) should be rapidly integrated in the communication network (Ethernet switches and electro-optical media-converters), while optical fibre uplinks are implemented to interconnect devices operating in the HVD. The software solution was to adopt Labview as the core of the control and of the acquisition systems (with the development of a synoptic panel) and MDSplus (including the most recent features, like support for long pulse discharge and MDSplus-Labview integration) for data archiving, distribution and visualization. A description is also given of the interlocks that are presently implemented to protect NIO1 against failures of the cooling system and to detect high voltage breakdown occurrences and over-temperatures. A Relational Data Base (based on PostgreSQL) is used to store time-averaged (summary) data for subsequent efficient data analysis in any programming language via standard connectors.