Particle Beams as Controllable Complex Systems: Application of the Network Theory

High power neutral beam injectors, like those for ITER, must satisfy very demanding parameters (40 A of negative ion current accelerated up to 1 MV for one hour). They are made of various components, which influence each other, so that the global performances eventually require the simultaneous control of several interacting parameters: thus the NBI is an example of a complex system. In the present paper, complex network theory is applied to verify the controllability conditions of the NIO1 experiment, a particle beam source operating at Consorzio RFX (Padova, Italy). Previous work on the subject is adapted to NIO1, the controllability conditions are assessed and the driver nodes are identified; first comparison between theoretical predictions and experimental data is also discussed.