  We consider the instabilities of field perturbations around a homogeneous
background color-electric and/or -magnetic field in SU(2) pure gauge theory. We
investigate a number of distinct cases of background magnetic and electric
fields, and compute the dispersion relations in the linearised theory,
identifying stable and unstable momentum modes. In the case of a net
homogeneous non-abelian B-field, we compute the non-linear (quadratic and
cubic) corrections to the equation of motion, and quantify to what extent the
instabilities are tempered by these non-linearities.
