We identify a two stage filamentation regime for high power 10 μm multi-picosecond pulses propagating in the atmosphere. The first low intensity stage is mainly regularized by ionization through excitation induced dephasing, which can lead to strong pulse shortening downstream. This shortening, in turn causes a significant reduction of the many-body induced plasma, which changes the dynamics drastically. As a result, a distinct second stage is predicted where peak intensities are clamped at one order of magnitude higher than in the first stage. The complex dynamics found in the second stage can result in the spatial and temporal breakup of the wavepacket, reduction of ionization losses and extreme spectral broadening that could be used as a high energy broad range IR-backlighter for atmospheric applications.
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