Beam driven Alfven eigenmodes and fishbones in JET

Fast particle driven instabilities are investigated at low toroidal field B -0 approximate to 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 Alfven eigenmodes was observed during injection of t ritium beams into a tritium plasma and during the injection of deuterium be ams into a deuterium plasma but not during the injection of hydrogen beams into a hydrogen plasma. At high beta, beta(N) = beta/(I-p/B(T)a) > 2.5, hig h amplitude fishbones were observed and appeared to be correlated with the degradation of confinement.