The growth of m = 3 perturbations in elliptical vortices. After an elliptical vortex with aspect ratio of 4.3 is perturbed with an m = 3 disturbance, the perturbation grows exponentially, accompanied by filamentation. Filaments in the electron vortex data (left) are lost to the conducting circular boundary of the trap. This boundary also suppresses the growth rate of the m=3 modes slightly when compared with the free-space computational data (right).