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arXiv · 2207.02354

Ionization rate and plasma dynamics at 3.9 micron femtosecond photoionization of air

Adam Patel·Claudia Gollner·Rokas Jutas·Valentina Shumakova·Mikhail N. Shneider·Audrius Pugzlys·Andrius Baltuska·Alexey Shashurin
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Abstract

The introduction of mid-IR optical parametric chirped pulse amplifiers (OPCPAs) has catalyzed interest in multi-millijoule, infrared femtosecond pulse-based filamentation. As tunneling ionization is a fundamental first stage in these high-intensity laser-matter interactions, characterizing the process is critical to understand derivative topical studies on femtosecond filamentation and self-focusing. Here, we report constructive-elastic microwave scattering-based measurements of total electron count, electron number densities, and photoionization rates generated by 3.9 micron femtosecond mid-infrared tunneling ionization of atmospheric air. Consequently, we determine photoionization rates in the range of 5.0x10$^{8}$-6.1x10$^{9}$ s$^{-1}$ for radiation intensities 1.3x10$^{13}$-1.9x10$^{14}$ W/cm$^{2}$, respectively. The proposed approach paves the wave to precisely tabulate photoionization rates in mid-IR for broad range of intensities and gas types and to study plasma dynamics at mid-IR filamentation.

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Adam Patel, Claudia Gollner, Rokas Jutas, Valentina Shumakova, Mikhail N. Shneider, Audrius Pugzlys, Andrius Baltuska, Alexey Shashurin. 2022-07-05. Ionization rate and plasma dynamics at 3.9 micron femtosecond photoionization of air. https://doi.org/10.1103/physreve.106.055210

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