  Nonlinear self-guided propagation of intense long-wave infrared (LWIR) laser
pulses is of significant recent interest owing to the high critical power for
self-focusing collapse at long wavelengths. This promises transmission of very
high power in a single filament as opposed to beam breakup and
multi-filamentation. Here, using the most current picture of LWIR ionization
processes in air, we present extensive simulations showing that isolated
avalanche sites centered on aerosols can arrest self-focusing, providing a
route to self-guided propagation of moderate intensity LWIR pulses in outdoor
environments.
