Beam driven Alfvén eigenmodes and fishbones in JET

Fast particle driven instabilities are investigated at low toroidal field B0 » 1 T in tritium, deuterium and hydrogen plasmas. Tritium, deuterium and hydrogen neutral beams with energies of 160, 140 and 110 keV were injected, respectively, into tritium, deuterium and hydrogen plasmas. The destabilization of Alfvén eigenmodes was observed during injection of tritium beams into a tritium plasma and during the injection of deuterium beams into a deuterium plasma but not during the injection of hydrogen beams into a hydrogen plasma. At high beta, bN = b/(Ip/BT a) > 2.5, high amplitude fishbones were observed and appeared to be correlated with the degradation of confinement.