Thomson and collisional regimes of in-phase coherent microwave scattering off gaseous microplasmas.

Autor: Patel AR; School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN, USA., Ranjan A; School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN, USA., Wang X; School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN, USA., Slipchenko MN; School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA., Shneider MN; Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA., Shashurin A; School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN, USA. ashashur@purdue.edu.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2021 Dec 03; Vol. 11 (1), pp. 23389. Date of Electronic Publication: 2021 Dec 03.
DOI: 10.1038/s41598-021-02500-y
Abstrakt: The total number of electrons in a classical microplasma can be non-intrusively measured through elastic in-phase coherent microwave scattering (CMS). Here, we establish a theoretical basis for the CMS diagnostic technique with an emphasis on Thomson and collisional scattering in short, thin unmagnetized plasma media. Experimental validation of the diagnostic is subsequently performed via linearly polarized, variable frequency (10.5-12 GHz) microwave scattering off laser induced 1-760 Torr air-based microplasmas (287.5 nm O 2 resonant photoionization by ~ 5 ns, < 3 mJ pulses) with diverse ionization and collisional features. Namely, conducted studies include a verification of short-dipole-like radiation behavior, plasma volume imaging via ICCD photography, and measurements of relative phases, total scattering cross-sections, and total number of electrons [Formula: see text] in the generated plasma filaments following absolute calibration using a dielectric scattering sample. Findings of the paper suggest an ideality of CMS in the Thomson "free-electron" regime-where a detailed knowledge of plasma and collisional properties (which are often difficult to accurately characterize due to the potential influence of inhomogeneities, local temperatures and densities, present species, and so on) is unnecessary to extract [Formula: see text] from the scattered signal. The Thomson scattering regime of microwaves is further experimentally verified via measurements of the relative phase between the incident electric field and electron displacement.
(© 2021. The Author(s).)
Databáze: MEDLINE
Externí odkaz: