A5083262109- Plasma Diagnostics and Applications
- Electrohydrodynamics and Fluid Dynamics
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Plasma Applications and Diagnostics
- Magnetic Field Sensors Techniques
- Advanced Data Storage Technologies
- Magnetic confinement fusion research
- Particle accelerators and beam dynamics
- Silicon Carbide Semiconductor Technologies
- Astronomical Observations and Instrumentation
- Laser-induced spectroscopy and plasma
- Electrostatic Discharge in Electronics
- Astrophysical Phenomena and Observations
- High-pressure geophysics and materials
- Quantum, superfluid, helium dynamics
- Planetary Science and Exploration
- Astro and Planetary Science
- High voltage insulation and dielectric phenomena
- Semiconductor materials and devices
- Cryptographic Implementations and Security
- Astrophysics and Cosmic Phenomena
- Power Transformer Diagnostics and Insulation
United States Naval Research Laboratory
2015-2025
Massachusetts Institute of Technology
2013-2025
Kavli Institute for Particle Astrophysics and Cosmology
2024
United States Naval Academy
2022
University of California, Santa Barbara
2019
United States Air Force Research Laboratory
2019
U.S. Air Force Research Laboratory Directed Energy Directorate
2019
Leidos (United States)
2019
University of Cincinnati
2019
Naval Research Laboratory Spacecraft Engineering Division
2017
High-speed imaging of a Hall thruster plume reveals near-omnipresent rotating regions elevated light emission, dubbed spokes, in the annular discharge channel. Azimuthal oscillations have long been suggested to induce cross-field electron transport thrusters, but conclusive experimental identification such with probes is often challenging. However, simple processing high-speed images taken at few tens thousands frames per second clearly long-wavelength spokes very low frequencies,...
This article provides recommended methods for building, operating, and taking plasma potential measurements from electron-emitting probes in electric propulsion devices, including Hall thrusters, gridded ion engines, others. The two major techniques, the floating point technique inflection technique, are described detail as well calibration error-reduction methods. heating various considerations emissive probe construction. Special plasmas addressed, high-energy densities, flows, magnetic...
We present integral field unit observations of the Phoenix Cluster with JWST Mid-infrared Instrument's Medium Resolution Spectrometer (MIRI/MRS). focus this study on molecular gas, dust, and star formation in brightest cluster galaxy (BCG). use precise spectral modeling to produce maps silicate polycyclic aromatic hydrocarbons (PAHs) inner $\sim$50 kpc cluster. have developed a novel method for measuring optical depth from silicates by comparing observed H$_2$ line ratios those predicted...
We present the TRansient Image Processing Pipeline (TRIPP), a transient and variable source detection pipeline that employs both difference imaging light curve analysis techniques for astronomical data. Additionally, we demonstrate TRIPP's rapid capability by detecting candidates in near-real time. TRIPP was tested using image data of supernova SN2023ixf from Local Galactic Transient Survey (LGTS) collected Las Cumbres Observatory's (LCO) network 0.4 m telescopes. To verify methods employed...
We discuss our transient search for directed energy systems in local galaxies, with calculations indicating the ability of modest searches to detect optical Search Extraterrestrial Intelligence (SETI) sources closest galaxies. Our analysis follows Lubin (2016) where a messenger civilization beacon strategy we call "intelligent targeting." plot required laser time achieve an SNR 10 and find blind transmission target all stars Milky Way be achievable galactic civilizations. As high cadence sky...
A methodology of modeling nonplanar surfaces, in which the microscale features emission sites can be orders magnitude smaller than mesoscale defining active area, has been developed and applied to both ordered arrays identical emitters random variations characteristic a roughened surface. The combines general thermal-field-photoemission model for electron emission, point charge evaluation field enhancement factors surface geometry, Ballistic-Impulse account trajectories electrons close...
The first direct experimental measurements of electron current due to rotating spokes in a modern highpower Hall thruster are presented. A segmented anode consisting 12 equally spaced azimuthal sections has been retrofitted onto the H6 6-kW class and operated at power levels up 3 kilowatts. Independent discharge on each segment 1 MHz synchronous high-speed video 87,500 frames per second reveal that visible spoke structures channel correspond local oscillations with amplitude approximately...
A methodology for implementing the recently developed reformulated general thermal-field equation describing simultaneous thermal and field emission contributions to electron is developed, with modifications directed enhancing speed accuracy of computation as demanded by emitter characterization beam simulations. An accurate factor correct both (TF) high (Fowler-Nordheim or FN) predictions based on a rapid Lorentzian fit model given. The analytic protrusion constructed from point dipole that...
The plasma plume of a 6 kW Hall Effect Thruster (HET) has been investigated in order to determine time-averaged and time-resolved properties 2-D plane. HETs are steady-state devices with multitude kilohertz faster oscillations that poorly understood yet impact their performance may interact spacecraft subsystems. known operate different modes differing efficiencies characteristics, particularly the axial breathing mode azimuthal spoke mode. In investigate these phenomena, high-speed...
A sheath theory for RF plasma cathodes is developed based on an analogy with asymmetric double probe. It shown that the family of curves produced expected to collapse onto a single curve under normalization discharge current ion saturation and voltage electron temperature. This combined global model numerically study anticipated performance trends in Ar discharge. These simulations are followed experimental measurements cathode using Ar. The capture qualitative trends, notably...
Hall thrusters are susceptible to large-amplitude plasma oscillations that impact thruster performance and lifetime also difficult model. High-speed cameras a popular tool study these dynamics due their spatial resolution popular, nonintrusive complement in situ probes. video of can be isolated (decomposed) into coherent structures (modes) with algorithms help us better understand the evolution interactions each. This work provides an introduction, comparison, step-by-step tutorial on...
Abstract The use of solar sail propulsion is investigated for both Mercury orbiter (MO) and sample return missions (MeSR). It will be demonstrated that can significantly reduce launch mass enhance payload fractions MO missions, while MeSR are enabled, again with a relatively low mass. Previous investigations type using electric have identified requirement an Ariane V launcher to deliver lander vehicle. analysis presented in this paper demonstrates that, principle, mission enabled single...
The process by which the mass density profile of certain galaxy clusters becomes centrally concentrated enough to produce high strong lensing (SL) cross-sections is not well understood. It has been suggested that baryonic condensation intracluster medium (ICM) due cooling may drag dark matter cores and thus steepen profile. In this work, we search for evidence ongoing ICM in first large, well-defined sample SL selected range 0.1 < z 0.6. Based on known correlations between rate both optical...
We present an improved heater design for thermionic cathodes using a rhenium filament encased in boron nitride ceramic sleeve. This is relatively simple to fabricate, yet has been successfully used reliably and repeatably light lanthanum hexaboride (LaB6) hollow cathode based on previously published without noticeable degradation over hundreds of hours operation. The high decomposition temperature (2800 C inert environments) melting point (3180 C) make this especially attractive use with...
High-power Hall thrusters capable of throughput on the order 100 kW are currently under development, driven by more demanding mission profiles and rapid growth in on-orbit solar power generation capability. At these levels nested thruster (NHT), a new design that concentrically packs multiple into single body with shared magnetic circuit, offers performance logistical advantages over conventional single-channel thrusters. An important area for risk reduction NHT development is quantifying...
With the rise of CubeSat usage there is a growing use-case for low Reynolds number nozzles as component within micro-propulsion systems. However, design such systems difficult due to viscous losses encountered in flow regimes. As part program develop tool efficient micro-nozzle design, performance test nozzle measured across range numbers create an experimental database model validation. The thrust and specific impulse efficiency are using torsional balance at various rates cover 60 – 500...
Plasma impedance probes (PIPs) are a type of RF probe that primarily measures electron density. This work introduces two advancements: streamlined analytical model for interpreting PIP-monopole measurements and techniques achieving ≥1 MHz time-resolved PIP measurements. The model’s improvements include introducing sheath thickness as measurement providing more accurate method measuring density damping. is validated by quasi-static numerical simulation, which compares the simulation with...
Electron sources exploiting field emission generally have sharp geometries in the form of cones and wires. Often, they operate under elevated temperatures. A sharply curved emitter affects barrier past which electrons must be emitted via thermal-field processes, as does a space charge metal-insulator-metal metal-oxide-semiconductor devices: all can examined using Gamow factor θ(E) on general equation is based. methodology to evaluate based shape methods given that emphasizes analytical...