arXiv subjects

Adam R. Patel

Publications and source records attributed to Adam R. Patel.

3 recordsLinked to original sources

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↗

arXiv2021

Thomson and Collisional Regimes of In-Phase Coherent Microwave Scattering Off Gaseous Microplasmas

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 microwave scattering off laser induced air-based microplasmas with diverse ionization and collisional features. Namely, conducted studies include a verification of short-dipole-like radiation behavior, plasma volume imaging via intensified charge-coupled device (ICCD) photography, and measurements of relative phases, total scattering cross sections, and total number of electrons $N_e$ in the generated plasma filaments following absolute calibration using a dielectric scattering sample. Findings of the paper suggest an ideality of the diagnostic 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 $N_e$ from the scattered signal.

physics.plasm-ph↗

arXiv2019

Liquid-Fed Pulsed Plasma Thruster for Propelling Nanosatellites

This paper presents a novel micropropulsion system for nanosatellite applications - a liquid fed pulsed-plasma thruster (LF-PPT) comprised of a Lorentz-force pulsed plasma accelerator (PPA) and a low-energy surface flashover (LESF) igniter. A 3 {\mu}F / 2 kV capacitor bank, offering shot energies of < 6 J, supported PPA current pulsed durations of ~ 16 {\mu}s with observed peaks of 7.42 kA. Plasma jet exhaust velocity was measured at ~ 32 km/s using a time-of-flight technique via a set of double probes located along the jet's path. Intensified charge coupled device (ICCD) photography was concurrently leveraged to visualize plasma dynamics and mechanisms of the ignition / acceleration events. A peak thrust and impulse bit of 5.8 N and 35 {\mu}Ns, respectively, were estimated using large-area Langmuir probe measurements of total ion flux produced by the thruster.

physics.app-ph↗