Comatic aberration-induced wavy vortex in gas

We investigate the evolution of laser-induced wavy vortex at 460 torr nitrogen gas environment. We show that Rayleigh-Taylor instability and Kelvin-Helmholtz instability are not the causes of the growth of the wavy vortex. Normal diffusion inducing the growth of the ripple-type perturbation is identified. The ratio of the perturbation amplitude to the wavelength of perturbation is found with 0.16. Through a quick estimation, measurements show the consistent scaling relations. We further show that the comatic aberration is suspected to be responsible for the asymmetric rarefaction wave, which triggers Kelvin-Helmholtz instability and induces the wavy vortex.