Spiking without and with blue-sky catastrophe

• Wayne Arter

Two closely-related candidate surrogate models for global tokamak plasma dynamics both exhibit spiking behaviour, which may be understood using concepts from the classical problem of particle motion in a well of potential energy. Numerical work indicates that when there is coupled evolution of the well’s properties, there is the bifurcation called the blue-sky catastrophe. The simplicity of the models is remarked upon and implications for the understanding of spiking activity are discussed.