  A non-equilibrium model for laser-induced plasmas is used to describe how
nano-second temporal mode-beating affects plasma kernel formation and growth in
quiescent air. The chemically reactive Navier-Stokes equations describe the
hydrodynamics, and non-equilibrium effects are modeled based on a
two-temperature model. Inverse Bremsstrahlung and multiphoton ionization are
self-consistently taken into account via a coupled solution of the equations
governing plasma dynamics and beam propagation and attenuation (i.e., Radiative
Transfer Equation). This strategy, despite the additional challenges it may
bring, allows to minimize empiricism and enables for more accurate simulations
since it does not require an artificial plasma seed to trigger breakdown. The
benefits of this methodology are demonstrated by the good agreement between the
predicted and the experimental plasma boundary evolution and absorbed energy.
The same goes for the periodic plasma kernel structures which, as suggested by
experiments and confirmed by the simulations discussed here, are linked to the
modulating frequency.
