arXiv subjects

A. Shashurin

Publications and source records attributed to A. Shashurin.

4 recordsLinked to original sources

arXiv2026

Experimental Characterization of Additively Manufactured Metallic Alloys for Electric Propulsion Applications

This work explores the sputtering of additively manufactured (AM) materials for use in gridded ion source applications. The first part of the paper uses 316L stainless steel as an example to demonstrate that additively manufactured material does not exhibit adverse sputtering behavior, such as higher sputter yield, compared with conventionally manufactured material. To this end, three additively manufactured 316L stainless steel samples were exposed to the beam of a KDC-40 electrostatic gridded ion source at three distinct energy levels of 400, 600, and 800 eV on each side of the sample for a duration of one hour. The samples were masked to create a distinct boundary between treated and untreated regions, identifiable using profilometry, and were biased to -18V for testing. Samples were then examined using a Bruker optical profilometer and further processed using the open-source software Gwyddion to evaluate the sputtering yield. The sputter yield varied in the range 0.2-2 atoms/ion for 400-800 eV ions and increased with ion energy. The measured sputtering yield was fairly consistent with predictions from analytical models developed in prior literature, while exhibiting some variations potentially due to added effects of increased temperature and oxide layers. The second part of the paper demonstrates feasibility of using an additively manufactured tungsten-rhenium grids in existing KDC-40 electrostatic gridded ion source.

physics.plasm-ph↗

arXiv2026

Focused Coherent Microwave Scattering for Spatially Resolved Electron Number Density Diagnostics

This work provides an initial demonstration of Focused Coherent Microwave Scattering (F-CMS) diagnostics technique, an extension of the conventional Coherent Microwave Scattering (CMS) technique that enables spatially resolved measurements. The spatial-resolution functionality was achieved using PTFE lenses to focus the probing microwave beam and isolate a distinct probing volume. The feasibility of F-CMS was demonstrated using glow-discharge plasma volume with an electron number density of approximately 5x10$^9$ cm$^{-3}$ as a test object. A clear F-CMS output signal was successfully detected upon the discharge initiation. These findings establish a foundation for the further development of the F-CMS technique, which has the potential to enable highly sensitive, spatiotemporally resolved measurements of electron number density in real time, without the need for signal accumulation (sensitivity down to an electron number density of approximately 10$^8$ cm$^{-3}$ is expected). Such capability will be useful for a variety of applications including diagnostics of unsteady flowfields such as those occurring in hypersonic shock tunnels and spacecraft electric propulsion systems.

physics.plasm-ph↗

arXiv2018

Direct measurement of electron numbers created at infrared laser-induced ionization of various gases

In this work, we present temporally resolved measurements of electron numbers created at photoionization of various gases by femtosecond laser pulse at 800 nm wavelength. The experiments were conducted in $O_2$, $Xe$, $Ar$, $N_2$, $Kr$ and $CO$ at room temperature and atmospheric pressure. Elastic microwave scattering was used to directly measure the electron numbers. Numbers of electrons in the range $3*10^8$ to $3*10^{12}$ electrons were produced by the laser pulse energies 100-700 uJ. After the laser pulse, plasma decayed on the time scale varied from 1 to 40 ns depending on the gas type and governed by two competing processes, namely, the creation of new electrons from ionization of the metastable atoms and loss of the electrons due to dissociative recombination and attachment to oxygen.

physics.plasm-ph↗

arXiv2017

Counting the electrons in a multiphoton ionization by elastic scattering of microwaves

Laser induced plasmas have found numerous applications including plasma-assisted combustion, combustion diagnostics, laser induced breakdown spectroscopy, light detection and ranging techniques (LIDAR), microwave guiding, reconfigurable plasma antennae etc. Multiphoton ionization (MPI) is a fundamental first step in high-energy laser-matter interaction and is important for understanding of the mechanism of plasma formation. With the discovery of MPI more than 50 years ago, there were numerous attempts to determine basic physical constants of this process in the direct experiments, namely photoionization rates and cross-sections of the MPI, however, no reliable data is available until today and spread in the literature values often reaches 2-3 orders of magnitude. This is due to inability to conduct absolute measurements of plasma electron numbers generated by MPI which leads to uncertainties and, sometimes, contradictions between the MPI cross-section values utilized by different researchers across the field. Here we report first direct measurement of absolute plasma electron numbers generated at MPI of air and subsequently we precisely determine ionization rate and cross-section of eight-photon ionization of oxygen molecule by 800 nm photons $σ_8=(3.32{\pm}0.3)*10^{-130} W^{-8}m^{16}s^{-1}$. Method is based on the absolute measurement of electron number created by MPI using elastic scattering of microwaves off the plasma volume in Rayleigh regime and establishes a general approach to directly measure and tabulate basic constants of the MPI process for various gases and photon energies.

physics.plasm-ph↗