Magnetic perturbations in ASDEX Upgrade facilitate power exhaust in a fusion plasma

Tokamaks can provide excellent confinement and high kinetic pressure of fusion plasmas due to an axisymmetric magnetic field. However, strong pressure gradients at the plasma edge cause repetitive instabilities leading to expulsion of hot plasma towards the surrounding wall. This instability is studied in detail at the tokamak ASDEX Upgrade. It has been found that the fast power loss from the plasma and the associated high peak power load onto the wall can be reduced by a small dedicated non-axisymmetric magnetic perturbation without compromising the favourable confinement properties.