Instrumentation and Control for the Neutral Beam Test Facility

The Neutral Beam Test Facility [1] is under construction in Padova, Italy with the aim of developing and testing the technologies needed to meet the advanced requirements of the ITER heating neutral beam injectors (HNBs). It includes two experiments, namely SPIDER, the fullsize ITER HNB ion source experiment, and MITICA the prototype of the ITER HNB. The construction of SPIDER is near to completion. SPIDER instrumentation and control (I&C) is classically organized in three tiers - conventional control, investment protection (interlock), and personnel safety - and three layers - central, plant system, and plant unit. Conventional control and the interlock systems have been already developed and tested and are ready to undergo the integrated commissioning along with important operation plant units such as the power supply, gas and vacuum, and cooling systems. Conventional control integrates a set of standard software frameworks [2]. It supports all functions that are typical of long-lasting fusion experiments, such as real-time control, event driven data acquisition, and data streaming. The interlock system provides fast (< 10 s reaction time) and slow (< 20 ms reaction time) protection functions. The safety system is under development and will include a set of safety-related functions associated with specific Safety Integrity Levels according to IEC 61508. The paper will present the architecture of the three-tier I&C system with reference to system requirements, technical solution proposed and issues found in the system development. In detail, the implementation of the interlock and safety tiers will be discussed with reference to the requirements set by ITER in the plant control design handbook. Finally, the SPIDER I&C example will be discussed with the perspective of the evolution towards the MITICA I&C for which the ITER constraints are stringent.