Destabilization of TAE modes using ICRH in ASDEX upgrade

Toroidicity-induced Alfven eigenmodes (TAEs) are destabilized in ASDEX Upgrade using ion cyclotron resonant heating (ICRH). Unstable TAEs are observed in the magnetic probes, reflectometer and soft x-ray cameras when the ICRH power exceeds P-ICRH > 2.5 MW in both conventional and advanced scenarios. The most unstable TAEs have toroidal mode numbers n = 3, 4, 5, 6, and experiments with reversed currents and magnetic fields have shown that the TAEs propagate in the co-current direction, i.e. in the ion diamagnetic drift direction, confirming that these modes are destabilized by the ICRH-produced energetic ions. The characterization of the TAE instability in ASDEX Upgrade is reported, focusing on the identification of the toroidal, poloidal and radial mode structures. The data are compared with the ideal magnetohydrodynamic model.