The influence of fishbones on the background plasma

Observations on ASDEX Upgrade show that fishbones can have a much stronger effect on the background plasma parameters than expected from an ideal, fast particle driven instability. They lead to a redistribution of electron temperature and impurity densities, similar in form and magnitude to sawteeth, albeit with the plasma parameter variation occurring on a significantly longer time-scale. Simulations of the current diffusion in discharges with favourable core confinement require fishbones to be furthermore associated also with magnetic reconnection to yield consistency between the conductivity and current profile information derived from ECE, bremsstrahlung, MSE and the localization of m = 1,n = 1 activity.