Observation of new branch of toroidal Alfven eigenmodes in TFTR

Experimental observations are presented of a new branch of the toroidal Alfven eigenmode spectrum during ICRF heating of plasmas on TFTR. The identification of the second branch is based largely on direct measurements of the toroidal mode numbers of the toroidal Alfven eigenmodes and by the differences in the time evolution of the frequency spectrum between the new branch and the original toroidal Alfven eigenmodes. The new branch has so far only been observed in relatively low edge q (= 4-4.5) plasmas.