Intense pulses in air: breakup of rotational symmetry

We investigate azimuthal instabilities of intense rotationally symmetric pulsed beams propagating in air. Although the spatial-temporal evolution of the field is strongly influenced by the onset of plasma generation, the instabilities are caused chiefly by the Kerr effect. We conclude that calculations that assume rotational symmetry become unrealistic because of the fast growth of azimuthal instabilities shortly after the onset of plasma generation.