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 (40A of negative ion current accelerated up to 1MV 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.