A hierarchy of electromagnetic gyrokinetic and fluid hybrid models for the simulation of global modes

Abstract

The goal of magnetic confinement fusion research is to produce an economically viable power reactor. This will require operation at finite plasma β, where for instance fast particle transport by Alfvén eigenmodes may become important. The density and energy of fast particles originating from heating and fusion will also be higher. Low frequency Alfvénic modes can be destabilised by fast particles, with velocities comparable to the Alfvén velocity, resulting in significant reduction of fast particle confinement. To properly predict and manipulate this behaviour in current and future fusion devices, the numerical simulation of fast particle interaction with Alfvén modes is necessary. Since these simulations are computationally demanding, it is desirable to use the simplest model capable of simulating a given phenomenon. Comparing a case with different physical models also permits the isolation of physics effects responsible for certain phenomena. In this paper we present a hierarchy of such numerical models and investigate their ranges of validity.