Nuclear Fusion, 50(11):115002, 2010. Paper Website abstract bibtex
A lumped parameter model for tokamak plasma current and inductance
time evolution as a function of plasma resistance, non-inductive
current drive sources and boundary voltage or poloidal field coil
current drive is presented. The model includes a novel formulation
leading to exact equations for internal inductance and plasma current
dynamics. Having in mind its application in a tokamak inductive control
system, the model is expressed in state space form, the preferred
choice for the design of control systems using modern control systems
theory. The choice of system states allows many interesting physical
quantities such as plasma current, inductance, magnetic energy, and
resistive and inductive fluxes be made available as output equations.
The model is derived from energy conservation theorem, and flux balance
theorems, together with a first order approximation for flux diffusion
dynamics. The validity of this approximation has been checked using
experimental data from JET showing an excellent agreement.