Physical Sciences and Mathematics Commons^™

A Study Of Electron Plasma Oscillations Using The Nimrod Code, Mckay Murphy

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

A plasma, whether ”hot” or ”cold,” magnetized or unmagnetized, electrostatic or electromagnetic, exhibits normal modes of oscillation. Critical to understanding the stability of a plasma is the study of these normal modes. Waves originate from the long-range electric interactions between charged particles. This work will consider a class of waves known as Langmuir waves. These waves occur when a group of electrons are displaced with respect to the ions, with the electric Coulomb force playing the role of the restoring force of the oscillation [1]. Since the mass of ions is much greater than that of electrons, we can approximate …

Improving The Efficiency Of The Preconditioning Of Iterative Solutions To The Kinetic Equation, D. Caleb Price

Physics Capstone Projects

To achieve the reality of fusion, a greater understanding of plasma is required. The kinetic equation can be evolved simultaneously alongside the fluid equations to solve for kinetic closures. NIMROD performs this with numerical solvers where the General Minimum Residual (GMRES) solver becomes more efficient with a preconditioning matrix as input. Using a GPU-enabled library, the efficiency of GPU offloading to the preconditioning step was tested. A significant decrease in the factoring time of preconditioning matrix was observed. This suggests that the allocation of GPUs is worth investigating for NIMROD’s own benefit, but also anyone seeking to improve the efficiency …

Simultaneous In Situ Measurements Of Small-Scale Structures In Neutral, Plasma, And Atomic Oxygen Densities During The Wadis Sounding Rocket Project, Boris Strelnikov, Martin Eberhart, Martin Friedrich, Jonas Hedin, Mikhail Khaplanov, Gerd Baumgarten, Bifford P. Williams, Tristan Staszak, Heiner Asmus, Irina Strelnikova, Ralph Latteck, Mykhaylo Grygalashvyly, Franz-Josef Lübken, Josef Höffner, Raimund Wörl, Jörg Gumbel, Stefan Löhle, Stefanos Fasoulas, Markus Rapp, Aroh Barjatya, Michael J. Taylor, Pierre-Dominique Pautet

Publications

In this paper we present an overview of measurements conducted during the WADIS-2 rocket campaign. We investigate the effect of small-scale processes like gravity waves and turbulence on the distribution of atomic oxygen and other species in the mesosphere–lower thermosphere (MLT) region. Our analysis suggests that density fluctuations of atomic oxygen are coupled to fluctuations of other constituents, i.e., plasma and neutrals. Our measurements show that all measured quantities, including winds, densities, and temperatures, reveal signatures of both waves and turbulence. We show observations of gravity wave saturation and breakdown together with simultaneous measurements of generated turbulence. Atomic oxygen inside …

Hybrid Iterative Approach For Simulation Of Radio-Frequency Fields In Plasma, Vladimir A. Svidzinski, Jin-Soo Kim, Liangji Zhao, S. A. Galkin, Joseph Andrew Spencer

Physics Student Research

A novel iterative approach for solving discretized linear wave equations in a frequency domain, which combines time evolution with iterative relaxation schemes, is presented. In this hybrid approach, each iteration cycle consists of evolution of electromagnetic (EM) fields in time over a specified number of field periods followed by several iterative relaxations. Provided that there is sufficient dissipation, both the time evolution and the iterative relaxations contribute to the convergence of the EM fields to the solution of the formulated full wave boundary value problem. Time evolution rapidly distributes EM fields, propagating with group velocity, over the simulation domain, while …

Electrically Induced Plasma, Nate Ashby

Physics Capstone Projects

My research project, under the mentorship of research professor Ajay Singh was to prove that the plasma he was creating was lasting longer than the electrical current data indicated. He decided that if the plasma was still there, it would be producing light. So we set out to prove that the light emitted from his plasma lasted longer than the current draw measurements.

Langmuir Probes In A Microwave Generated Plasma, Wesley Rawlins

Physics Capstone Projects

In this work, we considered a microwave generated plasma, in a toroidal device. In this set up, we tend to meet the conditions for several known plasma instabilities. Not all the gas in the chamber was ionized. Using a Langmuir probe we were able to determine the population temperature and the plasma density in the chamber. The existence of a plasma was determined by measuring the strength of reflected microwaves. We varied the fill pressure in the chamber, as well as the strength of an externally imposed magnetic field. From this, we determined that the plasma temperature decreased with an …

Enhanced Lunar Semidiurnal Equatorial Vertical Plasma Drifts During Sudden Stratospheric Warmings, Bela G. Fejer, B. D. Tracy, J. L. Chau

Bela G. Fejer

[1] Large scale electrodynamic and plasma density variations in the low latitude ionosphere have recently been associated with sudden stratospheric warming (SSW) events. We present average patterns of largely enhanced lunar semidiurnal equatorial vertical plasma drift perturbations during arctic winter low and high solar flux SSW events. These perturbations play a dominant role in the electrodynamic response of the low latitude ionosphere to SSWs. Our models indicate that the amplitudes of the enhanced lunar semidiurnal drifts are strongly local time and solar flux dependent, with largest values during early morning low solar flux SSW periods. These results suggest that ionospheric …

Relevance Of Ground-Based Electron-Induced Electrostatic Discharge Measurements To Space Plasma Environments, Jennifer A. Roth, Ryan Hoffmann, John R. Dennison, Jonathon R. Tippetts

All Physics Faculty Publications

Electron-induced electrostatic discharge (ESD) can lead to severe spacecraft anomalies. It is crucial to the success of space missions that the likelihood of ESD occurrence is understood and mitigated. To aid in predicting ESD occurrence, a model for electric fields above and below the charge layer inside an electronirradiated dielectric material was developed. An instrumentation system was also designed to induce and detect ESD events. Because ESD events with a wide range of maximum current values can occur over a range of time intervals, multiple simultaneous detection methods were employed as charge was accumulated on a sample surface; these included …

The Adaptability Of Langmuir Probes To The Pico-Satellite Regime, Andrew Jay Auman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this thesis is to investigate whether it is feasible to use Langmuir probes on pico-satellites flying in low Earth orbit over mid- to low-latitude geographic regions. Following chapters on the expected ionospheric conditions and an overview of Langmuir probe theory, a chapter addressing the difficulties involved with pico-satellite Langmuir probes is presented. Also, the necessary satellite-to-probe surface area requirements in order to achieve confidence in pico-satellite Langmuir probe data, for the orbital regions of interest to this thesis, are stated.

Seasonal And Longitudinal Dependence Of Equatorialdisturbance Vertical Plasma Drifts, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We used equatorial measurements from the ROCSAT-1 satellite to determine the seasonal and longitudinal dependent equatorial F region disturbance vertical plasma drifts. Following sudden increases in geomagnetic activity, the prompt penetration vertical drifts are upward during the day and downward at night, and have strong local time dependence at all seasons. The largest prompt penetration drifts near dusk and dawn occur during June solstice. The daytime disturbance dynamo drifts are small at all seasons. They are downward near dusk with largest (smallest) values during equinox (June solstice); the nighttime drifts are upward with the largest magnitudes in the postmidnight …

Quiet Time Equatorial F Region Vertical Plasma Drift Model Derived From Rocsat-1 Observations, Bela G. Fejer, J. W. Jensen, S. Y. Su

Bela G. Fejer

[1] We have used five years of measurements on board the ROCSAT-1 satellite to develop a detailed quiet time global empirical model for equatorial F region vertical plasma drifts. This model describes the local time, seasonal and longitudinal dependence of the vertical drifts for an altitude of 600 km under moderate and high solar flux conditions. The model results are in excellent agreement with measurements from the Jicamarca radar and also from other ground-based and in situ probes. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December …

Climatology Of Middle And Low-Latitude F-Region Plasma Drifts From Satellite Measurements, John W. Jensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

We used ion drift observations from the DE-2 satellite to study for the first time the longitudinal variations of middle and low latitude F-region zonal plasma drifts during quiet and disturbed conditions. The daytime quiet-time drifts do not change much with longitude. In the dusk-premidnight period, the equinoctial middle latitude westward drifts are smallest in the European sector, and the low latitude eastward drifts are largest in the American-Pacific sector. The longitudinal variations of the late night-early morning drifts during June and December solstice are anti-correlated. During geomagnetically active time s, there are large westward perturbation drifts in the late …

Climatology Of F Region Zonalplasma Drifts Over Jicamarca, Bela G. Fejer, J. R. Souza, A. S. Santos, A. E. Costa Pereira

Bela G. Fejer

[1] We use extensive incoherent scatter radar observations made at the Jicamarca Radio Observatory between 1970 and 2003 to study and model empirically the equatorial zonal plasma drifts near the F region peak using Bernstein polynomials as base functions. Our quiet-time model results confirm that the daytime drifts are westward and are nearly season and solar cycle independent. The nighttime drifts are eastward, have larger magnitudes, and increase strongly with solar flux, particularly near equinox and December solstice. Enhanced geomagnetic activity drives small eastward perturbation drifts during the day and much larger westward disturbance drifts at night. The nighttime drift …

Magnetospheric Electric Fields And Plasma Sheet Injections To Low-Lshells During The June 4-5, 1991 Magnetic Storm: Comparison Between The Rice Convectionmodel And Observations, T. W. Garner, R. A. Wolf, R. W. Spiro, W. J. Burke, Bela G. Fejer, S. Sazykin, J. L. Roeder, M. R. Hairston

Bela G. Fejer

[1] The major magnetic storm of 4–5 June 1991 was well observed with the Combined Release and Radiation Experiment (CRRES) satellite in the duskside inner magnetosphere and with three Defense Meteorological Satellite Program (DMSP) spacecraft in the polar ionosphere. These observations are compared to results from the Rice Convection Model (RCM), which calculates the inner magnetospheric electric field and particle distribution self-consistently. This case study, which uses the most complete RCM runs to date, demonstrates two significant features of magnetospheric storms, the development of subauroral polarization streams (SAPS) and plasma-sheet particle injection deep into the inner magnetosphere. In particular, the …

Experimental Investigation Of Snapover: The Sudden Increase Of Plasma Current Drawn To A Positively Biased Conductor When Surrounded By A Dielectric, Clint D. Thomson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Snapover is particularly relevant to Earth-orbiting spacecraft powered by high-voltage solar arrays. During snapover, the current collected by a positively biased conductor that is immersed in a plasma suddenly increases when two conditions are met: i) there is an immediately adjacent insulator; ii) the conductor exceeds a positive threshold voltage with respect to the plasma. The enhanced current develops as a consequence of the insulator, either through secondary electron (SE) emission or by material ionization. Experiments were performed to examine snapover onset potential and current collection dependence on conductor and insulator materials, conductor size and shape, sample history, biasing rate, …

Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto

Bela G. Fejer

We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the …

De-2 Observations Of Morningside And Eveningside Plasma Density Depletions In The Equatorial Ionosphere, M. Palmroth, H. Laakso, Bela G. Fejer, R. F. Pfaff

Bela G. Fejer

The occurrence of equatorial density depletions in the nightside F region ionosphere has been investigated by using observations gathered by the polar-orbiting Dynamics Explorer 2 satellite from August 1981 to February 1983. A variety of electric field/plasma drift patterns were observed within these depletions, including updrafting, downdrafting, bifurcating, converging, subsonic, and supersonic flows. The depletions, 116 events in total, are distributed over two groups: group I (eveningside depletions) consists of the events in the 1900–2300 MLT sector, and group II (morningside depletions) are the events in the 2300–0600 MLT sector. A statistical analysis reveals clear differences in the density depletion …

Snapover: Anomalous Plasma Current Collection By Positively Biased Conductors When Surrounded By A Dielectric, Clint Thomson, John R. Dennison

All Physics Faculty Publications

Over the last decade, high-powered spacecraft have been designed that will operate at voltages greater than 100 V. At these voltages, the solar arrays can undergo both destructive arcing at negative biases, and plasma electron current collection at positive biases. Furthermore, above some critical positive bias voltage (~100 V), the electron current collected by the array interconnects increases dramatically through a phenomenon termed Asnapover@. During snapover, large portions of the solar array cover glass charge positively, and begin to draw electron current from the plasma as if it were a conducting surface. This leads to substantial power losses for the …

Investigation Of The First Snapover Of Positively Biased Conductors In A Plasma, C. D. Thomson, John R. Dennison, R. E. Davies, D. C. Ferguson, J. T. Galafaro, B. V. Vayner

All Physics Faculty Publications

We describe a systematic experimental investigation of the phenomenon termed "snapover." In snapover, the current collected by a positively biased conductor, surrounded by a dielectric and immersed in a plasma, increases dramatically when the conductor potential is raised above some threshold value. The phenomenon is particularly relevant to the case of high-voltage solar arrays in Earth orbit. Our experiments examined the importance of conducting material, insulating material, size and shape of the conductor, sample history, biasing rate, and condition of the dielectric surface (contamination and smoothness) to the onset potential and current jump. In addition to a primary snapover occurring …

Effects Of The Vertical Plasma Drift Velocity On The Generation And Evolution Of Equatorial Spread F, Bela G. Fejer, L. Scherliess, E. R. De Paula

Bela G. Fejer

We use radar observations from the Jicamarca Observatory from 1968 to 1992 to study the effects of the F region vertical plasma drift velocity on the generation and evolution of equatorial spread F. The dependence of these irregularities on season, solar cycle, and magnetic activity can be explained as resulting from the corresponding effects on the evening and nighttime vertical drifts. In the early night sector, the bottomside of the F layer is almost always unstable. The evolution of the unstable layer is controlled by the history of the vertical drift velocity. When the drift velocities are large enough, the …

The Conductor-Dielectric Junctions In A Low Density Plasma, B. V. Vayner, J. T. Galofaro, D. C. Ferguson, Win De Groot, Clint Thomson, John R. Dennison, Robert Davies

All Physics Faculty Publications

A conductor-dielectric junction exposed to the space environment is a frequent spacecraft design feature. Due to spacecraft charging and/or solar array operation, the conductor can acquire a high potential with respect to the surrounding plasma. If this potential is positive the insulators adjacent to exposed conductors can collect current as if they were conductors themselves. This phenomenon, called snapover, results in a substantial increase in current collection, and may even result in a glow discharge if the potential is high enough. If a conductor has a negative potential, arcing can occur at the site of a junction. Both of these …

Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess

Bela G. Fejer

We have used ion drift observations from the DE-2 satellite to determine the latitudinal variation and the temporal evolution of mid- and low-latitude prompt penetration zonal plasma drifts driven by magnetospheric electric fields. Our results indicate that sudden increases in convection lead to predominantly westward perturbation drifts which decrease equartorwards and have largest amplitudes in the dusk-midnight sector. The diurnal perturbation drift patterns shift to later local times with increasing storm time and decay to new quasi-equilibrium values in about 2 hours, as the ring current readjusts to the new polar cap potential. The daily and latitudinal variations and temporal …

Satellite Studies Of Mid- And Low-Latitude Ionospheric Disturbancezonal Plasma Drifts, L. Scherliess, Bela G. Fejer

Bela G. Fejer

We use low- and mid-latitude zonal ion drift observations from the DE-2 satellite and auroral electrojet indices to study the temporal and latitudinal variations of F-region perturbation drifts during magnetically disturbed conditions. These perturbation drifts are driven by magnetospheric and ionospheric disturbance dynamo electric fields with time constants from less than one to several hours. We determine, initially, the drift patterns due to the prompt penetration of magnetospheric electric fields and of longer lasting disturbances. In this study, we concentrate on the properties of the longer lasting perturbations which occur with latitude-dependent time delays after enhancements in the high-latitude ionospheric …

Global Equatorial Ionosphericvertical Plasma Drifts Measured By The Ae-E Satellite, Bela G. Fejer, E. R. De Paula, R. A. Heelis, W. B. Hanson

Bela G. Fejer

Ion drift meter observations from the Atmosphere Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes ≤ 7.5°) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement from solar minimum to maximum. The diurnal, seasonal, and solar cycle dependence of the longitudinally averaged drifts are consistent with results from the Jicamarca radar except …

A Monte Carlo Simulation Of Coulomb Collisions And Wave-Particle Interactions In Space Plasma At High Latitudes, Imad Ahmad Barghouthi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Four studies were considered to simulate the ion behavior in the auroral region and the polar wind.

In study I, a Monte Carlo simulation was used to investigate the behavior of O⁺ ions that are E x B-drifting through a background of neutral O, with the effect of O⁺(Coulomb) self-collisions included. Wide ranges of the ion-to-neutral density ratio n_i / n_n and electrostatic field E were considered in order to investigate the change of ion behavior with respect to the solar cycle and altitude. For low altitudes and/or solar minimum (n_i / …

F-Region Plasma Drifts Over Arecibo: Solar Cycle, Seasonal And Magnetic Activityeffects, Bela G. Fejer

Bela G. Fejer

We have used Arecibo incoherent scatter measurements from 1981 to 1990 to determine the characteristics of low-latitude F region plasma drifts. The measurements show large day-to-day variability even during magnetically quiet periods. The average poleward/perpendicular plasma drifts do not change significantly with season and solar cycle except in the midnight-morning sector. The zonal drifts show clear solar cycle and seasonal effects. The afternoon-nighttime eastward drifts increase with solar flux; the westward drifts in the early morning-afternoon sector show a large increase from summer to winter but are independent of solar activity. The two perpendicular velocity components also respond differently to …

Average Vertical And Zonal F-Region Plasma Drifts Over Jicamarca, Bela G. Fejer, E. R. De Paula, S. Gonzalez, R. F. Woodman

Bela G. Fejer

The seasonal averages of the equatorial F region vertical and zonal plasma drifts are determined using extensive incoherent scatter radar observations from Jicamarca during 1968–1988. The late afternoon and nighttime vertical and zonal drifts are strongly dependent on the 10.7-cm solar flux. We show that the evening prereversal enhancement of vertical drifts increases linearly with solar flux during equinox but tends to saturate for large fluxes during southern hemisphere winter. We examine in detail, for the first time, the seasonal variation of the zonal plasma drifts and their dependence on solar flux and magnetic activity. The seasonal effects on the …

Equatorial F-Regionvertical Plasma Drifts During Solar Maxima, Bela G. Fejer, E. R. De Paula, I. S. Batista, E. Bonelli, R. F. Woodman

Bela G. Fejer

Incoherent scatter radar measurements at Jicamarca are used to study the effects of large solar fluxes and magnetic activity on the F region vertical plasma drifts. The average drifts from the two last solar maxima are almost identical except in the late afternoon-early evening sector where their variations with solar flux and magnetic activity are strongly season dependent. The average evening winter (May-August) drifts appear to remain almost constant after a certain solar flux level is reached but increase with magnetic activity. The equinoctial evening drifts increase systematically with solar-flux but decrease with magnetic activity. Very large prereversal enhancement velocities, …

Electric Field And Plasmadensity Measurements In The Strongly-Driven Daytime Equatorial Electrojet: 1. The Unstablelayer And Gradient Drift Waves, R. F. Pfaff, M. C. Kelley, E. Kudeki, Bela G. Fejer, K. D. Baker

Bela G. Fejer

Electric field and plasma density instrumentation on board a sounding rocket launched from Punta Lobos, Peru, detected intense electrostatic waves indicative of plasma instabilities in the daytime equatorial electrojet. Simultaneous measurements taken by the Jicamarca radar showed strong 3-m type 1 electrojet echoes as well as evidence of kilometer scale horizontally propagating waves. The in situ electric field wave spectra displayed three markedly different height regions within the unstable layer: (1) a two-stream region on the topside between 103 and 111 km where the electron current was considered to be strongest, (2) a gradient drift region between 90 and 106.5 …

Electric Field And Plasmadensity Measurements In The Strongly-Driven Daytime Equatorial Electrojet: 2. Two-Streamwaves, R. F. Pfaff, M. C. Kelley, E. Kudeki, Bela G. Fejer, K. D. Baker

Bela G. Fejer

Both primary and secondary two-stream (Farley-Buneman) waves have been detected by in situ electric field and plasma density probes in the strongly driven daytime equatorial electrojet over Peru. Simultaneous Jicamarca radar observations showed strong vertical and oblique 3-m type 1 echoes, also indicative of the two-stream mechanism. The rocket data show the two-stream region on the topside of the unstable layer to be situated between 103 and 111 km where the electron current was the strongest. This region was characterized by broadband plasma oscillations extending past 1 kHz in the rocket frame. Furthermore, above 106.5 km, where the electron density …