The fishbone instability in asdex upgrade

摘要

In ASDEX Upgrade the excitation of the fishbone instability has been experimen- tally investigated. The initial frequency of the fishbone oscillation scales with the toroidal precession frequency of the fast trapped ions. A new features, the coupling of the fishbone mode with the edge localized mode(ELM)instability during high-βdischarges, is found. Fishbone occur in ASDEX Upgrade only forβ_fast=β_tor/(1+τE/τ_sd)above a certain threshold. It is thus possible to calculate Their destabilization regime in terms of global plasma parameters, such as plasma current, plasma Density, toroidal magnetic field and central electron temperature.