arXiv subjects

Nicholas Babusis

Publications and source records attributed to Nicholas Babusis.

3 recordsLinked to original sources

arXiv2026

Absolute Radar-REMPI via Two-Color REMPI and Absolutely Calibrated CMS for Diagnostics of Species in Gaseous Mixtures

This work demonstrates the initial development of the Absolute Radar-REMPI diagnostic technique, a development of the Radar-REMPI technique that provides an approach for absolutely calibrated measurements, which is universally applicable to any type of tested gaseous species. Absolute measurements are achieved through the utilization of two-color Resonance Enhanced Multiphoton Ionization (REMPI) and absolutely calibrated Coherent Microwave Scattering (CMS). Two-color REMPI of molecular oxygen (O2) was demonstrated using two intersected laser beams: a 355 nm beam and a tunable parametric beam at 241-242 nm. The results confirm that the two-beam configuration can successfully generate measurable ionization associated with the targeted transition of O2 within the beam intersection region, as verified using an ICCD camera. These findings establish a foundation for the further development of Absolute Radar-REMPI, which has the potential to enable highly sensitive, real-time diagnostics of absolute species densities in unsteady flowfields such as those occurring in hypersonic shock tunnels and electric propulsion systems.

physics.plasm-ph↗

arXiv2024

One-dimensional mapping of femtosecond laser filaments using coherent microwave scattering

This paper reports on the use of coherent microwave scattering (CMS) for spatially resolved electron number density measurements of elongated plasma structures induced at mid-IR femtosecond filamentation in air. The presented studies comprise one-dimensional mapping of laser filaments induced via 3.9 um, 127.3 fs laser pulses at output energies up to 15 mJ. The axial electron number density was measured to be invariant (about 2x10$^{15}$ cm$^{-3}$) along the entire filament length and for all tested laser pulse energies 5-15 mJ, and the corresponding laser intensity in the middle portion of the filament was estimated to be nearly constant for 5-15 mJ pulse energies (about 30-40 TW/cm$^2$). These fundings support that intensity clamping conditions were achieved in the experiments. The proposed approach enables capabilities that are currently unavailable to perform absolute and longitudinally resolved measurements of electron number density in laser filaments and to precisely characterize conditions associated with self-focusing and intensity clamping.

physics.plasm-ph↗

arXiv2023

Application of Coherent Microwave Scattering and Multiphoton Ionization for Diagnostics of Electric Propulsion Systems

Nonintrusive measurements of plasma properties are essential to evaluate, and numerically simulate, the in-flight performance of electric propulsion systems. As a logical first step in the development of new diagnostic techniques, this work depicts the implementation of multiphoton ionization and coherent microwave scattering (MPI-CMS) in a gridded-ion accelerator operating on rare gases. Presented studies primarily comprise photoionization spectroscopy of ground and excited state-populations of both neutrals and ions supplemented by optical emission spectroscopy and Langmuir probe derived plume properties. Results suggest the potential of MPI-CMS for non-intrusive measurements of specie number densities.

physics.plasm-ph↗