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Articles 1 - 30 of 53
Full-Text Articles in Physics
Neutron Time Of Flight Spectrometry As A Diagnostic Tool For Inertial Electrostatic Confinement Fusion Plasmas, Andrew H. Dempsey, Erik J. Sanchez
Neutron Time Of Flight Spectrometry As A Diagnostic Tool For Inertial Electrostatic Confinement Fusion Plasmas, Andrew H. Dempsey, Erik J. Sanchez
Student Research Symposium
Inertial electrostatic confinement (IEC) is a method for achieving fusion of light nuclei wherein ions are injected into a spherically symmetric system of concentric electrodes. When the innermost electrode is held at negative high voltage with respect to the outer electrode, ions injected into the reactor at cathode (ground) potential accelerate toward the anode where they may undergo collisions with sufficient energy to overcome Coulomb repulsion and achieve nuclear fusion. The most commonly used IEC fusion fuels are deuterium-deuterium (D-D) and deuterium-tritium (D-T). Both fuels undergo fusion reactions that result in production of fast neutrons with distinct energies. Neutron production …
Energy Conversion In Plasmas Out Of Local Thermodynamic Equilibrium: A Kinetic Theory Perspective, Mahmud Hasan Barbhuiya
Energy Conversion In Plasmas Out Of Local Thermodynamic Equilibrium: A Kinetic Theory Perspective, Mahmud Hasan Barbhuiya
Graduate Theses, Dissertations, and Problem Reports
The study of energy conversion in collisionless plasmas that are not in local thermodynamic equilibrium (LTE) is at the leading edge of plasma physics research. Plasma constituents in such systems can exhibit highly structured phase space densities that deviate significantly from that of a Maxwellian. A standard approach has emerged in recent years for investigating energy conversion between bulk flow and thermal energy in collisionless plasmas using the non-LTE generalization of the first law of thermodynamics. The primary focus is placed on pressure-strain interaction (PS) term, with a particular emphasis on its non-LTE piece called Pi − D. Recent studies …
Reflection And Transmission Of Electromagnetic Pulses At A Planar Dielectric Interface: Theory And Quantum Lattice Simulations, Abhay K. Ram, George Vahala, Linda Vahala, Min Soe
Reflection And Transmission Of Electromagnetic Pulses At A Planar Dielectric Interface: Theory And Quantum Lattice Simulations, Abhay K. Ram, George Vahala, Linda Vahala, Min Soe
Electrical & Computer Engineering Faculty Publications
There is considerable interest in the application of quantum information science to advance computations in plasma physics. A particular point of curiosity is whether it is possible to take advantage of quantum computers to speed up numerical simulations relative to conventional computers. Many of the topics in fusion plasma physics are classical in nature. In order to implement them on quantum computers, it will require couching a classical problem in the language of quantum mechanics. Electromagnetic waves are routinely used in fusion experiments to heat a plasma or to generate currents in the plasma. The propagation of electromagnetic waves is …
Spectroscopic Diagnostics For Supersonic Air Microwave Discharges, James E. Caplinger
Spectroscopic Diagnostics For Supersonic Air Microwave Discharges, James E. Caplinger
Theses and Dissertations
Optical Emission Spectroscopy (OES) is an increasingly relevant technique in plasma diagnostics due to its inherent non-invasive nature and simple application relative to other popular techniques. In this work, common OES techniques are combined with novel methods, developed here, in an effort to provide comprehensive OES techniques for stationary and supersonic air microwave discharges. To this end, a detailed collisional-radiative model for strong atomic oxygen lines has been developed and used to identify the importance of often overlooked mechanisms including cascade emission and metastable excitation. Using these results, a combined argon actinometry technique was developed which makes use of the …
Pulse Power Effects On Transient Plasma Ignition For Combustion, David Wayne Alderman Ii
Pulse Power Effects On Transient Plasma Ignition For Combustion, David Wayne Alderman Ii
Electrical & Computer Engineering Theses & Dissertations
Transient plasma ignition (TPI) uses highly non-equilibrium plasmas, driven by less than 100 nanosecond, high-voltage pulses, to initiate combustion. The effects of pulse repetition frequency (PRF) and ultrashort nanosecond rise times on TPI are investigated in this work using lean, stoichiometric, and rich air-fuel mixtures at atmospheric pressure. Experimental data show the transient plasmas driven by ultrashort rise time, high voltage pulses at high PRF’s enhance the combustion of lean or stoichiometric air-methane mixtures in a static chamber. In particular, increasing PRF enhances the combustion performance by means of reduced delay times independent of the equivalence ratio of the air-fuel …
Oscillatory Behavior Of Hollow Grid Cathode Discharges, Roman Schrittwieser, Claudia-Teodora Teodorescu-Soare, Florin Enescu, Codrina Ionita, Dan-Gheorghe Dimitriu, Silviu Gurlui, Federico Mazzanti, Stefan-Andrei Irimiciuc, Bianca Hodoroaba, Turlough O'Hara, Ovidiu Vasilovici, Lidia Amarandi
Oscillatory Behavior Of Hollow Grid Cathode Discharges, Roman Schrittwieser, Claudia-Teodora Teodorescu-Soare, Florin Enescu, Codrina Ionita, Dan-Gheorghe Dimitriu, Silviu Gurlui, Federico Mazzanti, Stefan-Andrei Irimiciuc, Bianca Hodoroaba, Turlough O'Hara, Ovidiu Vasilovici, Lidia Amarandi
Conference Papers
Multiple complex space-charge structures in unmagnetized low-temperature plasmas arise from ionization phenomena near additional negatively or positively biased electrodes or due to local constraints. Because of their usually spherical form, such structures are called fireballs. If they appear inside hollow grids, they are called inverted fireballs or plasma bubbles. The temporal evolution of such structures is often accompanied by strong plasma instabilities. The dynamics of complex space-charge structures have been investigated by using single spherical grid cathode with an orifice. Langmuir probe and optical emission spectroscopy were used to diagnose the structures. Measurements delivered the axial profiles of the plasma …
Investigation On The Rons And Bactericidal Effects Induced By He + O2 Cold Plasma Jets: In Open Air And In An Airtight Chamber, Han Xu, Dingxin Liu, Weitao Wang, Zhijie Liu, Li Guo, Mingzhe Rong, Michael G. Kong
Investigation On The Rons And Bactericidal Effects Induced By He + O2 Cold Plasma Jets: In Open Air And In An Airtight Chamber, Han Xu, Dingxin Liu, Weitao Wang, Zhijie Liu, Li Guo, Mingzhe Rong, Michael G. Kong
Bioelectrics Publications
He + O2 plasma jets in open air and in an airtight chamber are comparatively studied, with respect to their production of gaseous/aqueous reactive species and their antibacterial effects. Under the same discharge power, the plasma jet in open air has higher densities of gaseous reactive species and a higher concentration of aqueous H2O2 but lower concentrations of aqueous OH and O2-. In addition, the increase in the O2 ratio in He in both plasma jets causes a linear decrease in the population of gaseous reactive species, except for O(3p5P) …
Suppression Of Dielectronic Recombination Due To Finite Density Effects. Ii. Analytical Refinement And Application To Density-Dependent Ionization Balances And Agn Broad-Line Emission, D. Nikolić, T. W. Gorczyca, K. T. Korista, Marios Chatzikos, Gary J. Ferland, Francisco Guzmán, P. A. M. Van Hoof, R. J. R. Williams, N. R. Badnell
Suppression Of Dielectronic Recombination Due To Finite Density Effects. Ii. Analytical Refinement And Application To Density-Dependent Ionization Balances And Agn Broad-Line Emission, D. Nikolić, T. W. Gorczyca, K. T. Korista, Marios Chatzikos, Gary J. Ferland, Francisco Guzmán, P. A. M. Van Hoof, R. J. R. Williams, N. R. Badnell
Physics and Astronomy Faculty Publications
We present improved fits to our treatment of suppression of dielectronic recombination at intermediate densities. At low densities, most recombined excited states eventually decay to the ground state, and therefore the total dielectronic recombination rate to all levels is preserved. At intermediate densities, on the other hand, collisions can lead to ionization of higher-lying excited states, thereby suppressing the dielectronic recombination rate. The improved suppression factors presented here, although highly approximate, allow summed recombination rate coefficients to be used to intermediate densities. There have been several technical improvements to our previously presented fits. For H- through B-like ions the activation …
Effect Of Self-Bias On Cylindrical Capacitive Discharge For Processing Of Inner Walls Of Tubular Structures-Case Of Srf Cavities, J. Upadhyay, J. Peshl, S. Popović, A.-M. Valente-Feliciano, L. Vušković
Effect Of Self-Bias On Cylindrical Capacitive Discharge For Processing Of Inner Walls Of Tubular Structures-Case Of Srf Cavities, J. Upadhyay, J. Peshl, S. Popović, A.-M. Valente-Feliciano, L. Vušković
Physics Faculty Publications
Cylindrical capacitive discharge is a convenient medium for generating reactive ions to process inner walls superconductive radio-frequency (SRF) cavities. These cavities, used in particle accelerators, presents a three-dimensional structure made of bulk Niobium, with axial cylindrical symmetry. Manufactured cavity walls are covered with Niobium oxides and scattered particulates, which must be removed for desired SRF performance. Cylindrical capacitive discharge in a mixture of Ar and Cl2 is a sole and natural non-wet acid choice to purify the inner surfaces of SRF cavities by reactive ion etching. Coaxial cylindrical discharge is generated between a powered inner electrode and the grounded …
Production And Correlation Of Reactive Oxygen And Nitrogen Species In Gas- And Liquid-Phase Generated By Helium Plasma Jets Under Different Pulse Widths, Zhijie Liu, Chunxi Zhou, Dingxin Liu, Dehui Xu, Wenjie Xia, Qingjie Cui, Bingchuan Wang, Michael G. Kong
Production And Correlation Of Reactive Oxygen And Nitrogen Species In Gas- And Liquid-Phase Generated By Helium Plasma Jets Under Different Pulse Widths, Zhijie Liu, Chunxi Zhou, Dingxin Liu, Dehui Xu, Wenjie Xia, Qingjie Cui, Bingchuan Wang, Michael G. Kong
Bioelectrics Publications
In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is …
Comparison Between The Water Activation Effects By Pulsed And Sinusoidal Helium Plasma Jets, Han Xu, Dingxin Liu, Wenjie Xia, Chen Chen, Weitao Wang, Zhijie Liu, Xiaohua Wang, Michael G. Kong
Comparison Between The Water Activation Effects By Pulsed And Sinusoidal Helium Plasma Jets, Han Xu, Dingxin Liu, Wenjie Xia, Chen Chen, Weitao Wang, Zhijie Liu, Xiaohua Wang, Michael G. Kong
Bioelectrics Publications
Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2−, and O2−/ONOO− induced by the …
Confocal Laser Induced Fluorescence With Comparable Spatial Localization To The Conventional Method, Derek S. Thompson, Miguel F. Henriquez, Earl E. Scime, Timothy N. Good
Confocal Laser Induced Fluorescence With Comparable Spatial Localization To The Conventional Method, Derek S. Thompson, Miguel F. Henriquez, Earl E. Scime, Timothy N. Good
Physics and Astronomy Faculty Publications
We present measurements of ion velocity distributions obtained by laser induced fluorescence (LIF) using a single viewport in an argon plasma. A patent pending design, which we refer to as the confocal fluorescence telescope, combines large objective lenses with a large central obscuration and a spatial filter to achieve high spatial localization along the laser injection direction. Models of the injection and collection optics of the two assemblies are used to provide a theoretical estimate of the spatial localization of the confocal arrangement, which is taken to be the full width at half maximum of the spatial optical response. The …
The Mechanism Of Plasma Plume Termination For Pulse Excited Plasmas In A Quartz Tube, Mingzhe Rong, Wenjie Xia, Xiaohua Wang, Zhijie Liu, Dingxin Liu, Zhihu Liang, Xiaoning Zhang, Michael G. Kong
The Mechanism Of Plasma Plume Termination For Pulse Excited Plasmas In A Quartz Tube, Mingzhe Rong, Wenjie Xia, Xiaohua Wang, Zhijie Liu, Dingxin Liu, Zhihu Liang, Xiaoning Zhang, Michael G. Kong
Bioelectrics Publications
Although the formation and propagation of plasma plume for atmospheric pressure plasmas have been intensively studied, how does the plasma plume terminate is still little known. In this letter, helium plasma plumes are generated in a long quartz tube by pulsed voltages and a constant gas flow. The voltages have a variable pulse width (PW) from 0.5 μs to 200 μs. It is found that the plasma plume terminates right after the falling edge of each voltage pulse when PW < 20 μs, whereas it terminates before the falling edge. When PW is larger than 30 μs, the …
Comment On "Roles Of Bulk Viscosity On Rayleigh-Taylor Instability: Non-Equilibrium Thermodynamics Due To Spatio-Temporal Pressure Fronts" Phys. Fluids 28, 094102 (2016), Robert L. Ash
Mechanical & Aerospace Engineering Faculty Publications
No abstract provided.
Multifractal And Monofractal Scaling In A Laboratory Magnetohydrodynamic Turbulence Experiment, D. A. Schaffner, Michael R. Brown
Multifractal And Monofractal Scaling In A Laboratory Magnetohydrodynamic Turbulence Experiment, D. A. Schaffner, Michael R. Brown
Physics & Astronomy Faculty Works
Both multifractal and monofractal scaling of structure function exponents are observed in the turbulent magnetic fluctuations of the Swarthmore Spheromak Experiment plasma. Structure function and probability distribution function (PDF) analysis exhibits multifractal scaling exponents in low frequency, inertial range fluctuations of the turbulence but monofractal scaling in higher frequency, dissipation range fluctuations. The transition from multifractal to monofractal scaling occurs rapidly suggesting a dissipation mechanism that is insensitive to turbulent structure scale size. Structure functions and PDFs are presented for both temporal and spatial measurements. Variations in the magnetic helicity in the plasma are also shown to modify multifractal scaling …
Accurate Determination Of The Free–Free Gaunt Factor – Ii. Relativistic Gaunt Factors, P. A. M. Van Hoof, Gary J. Ferland, R. J. R. Williams, K. Volk, Marios Chatzikos, M. Lykins, R. L. Porter
Accurate Determination Of The Free–Free Gaunt Factor – Ii. Relativistic Gaunt Factors, P. A. M. Van Hoof, Gary J. Ferland, R. J. R. Williams, K. Volk, Marios Chatzikos, M. Lykins, R. L. Porter
Physics and Astronomy Faculty Publications
When modelling an ionized plasma, all spectral synthesis codes need the thermally averaged free–free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists that would meet these needs completely. We have therefore produced a table of relativistic Gaunt factors over a much wider range of parameter space than has ever been produced before. We present tables of the thermally averaged Gaunt factor covering the range 10log γ2 = −6 to 10 and 10log u = −16 to 13 for …
Strongly-Coupled Plasmas Formed From Laser-Heated Solids, M. Lyon, Scott D. Bergeson, G. Hart, M. S. Murillo
Strongly-Coupled Plasmas Formed From Laser-Heated Solids, M. Lyon, Scott D. Bergeson, G. Hart, M. S. Murillo
Faculty Publications
We present an analysis of ion temperatures in laser-produced plasmas formed from solids with different initial lattice structures. We show that the equilibrium ion temperature is limited by a mismatch between the initial crystallographic configuration and the close-packed configuration of a strongly-coupled plasma, similar to experiments in ultracold neutral plasmas. We propose experiments to demonstrate and exploit this crystallographic heating in order to produce a strongly coupled plasma with a coupling parameter of several hundred.
Accurate Determination Of The Free–Free Gaunt Factor – I. Non-Relativistic Gaunt Factors, P. A. M. Van Hoof, R. J. R. Williams, K. Vollk, Marios Chatzikos, Gary J. Ferland, M. Lykins, R. L. Porter, Ye Wang
Accurate Determination Of The Free–Free Gaunt Factor – I. Non-Relativistic Gaunt Factors, P. A. M. Van Hoof, R. J. R. Williams, K. Vollk, Marios Chatzikos, Gary J. Ferland, M. Lykins, R. L. Porter, Ye Wang
Physics and Astronomy Faculty Publications
Modern spectral synthesis codes need the thermally averaged free–free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum emitted by an ionized plasma. Until now no set of data exists that would meet this need in a fully satisfactory way. We have therefore undertaken to produce a table of very accurate non-relativistic Gaunt factors over a much wider range of parameters than has ever been produced before. We first produced a table of non-averaged Gaunt factors, covering the parameter space 10log ϵi = −20 to +10 …
Radiative Cooling Ii: Effects Of Density And Metallicity, Ye Wang, Gary J. Ferland, Matt Lykins, R. L. Porter, Peter A. M. Van Hoof, R. J. R. Williams
Radiative Cooling Ii: Effects Of Density And Metallicity, Ye Wang, Gary J. Ferland, Matt Lykins, R. L. Porter, Peter A. M. Van Hoof, R. J. R. Williams
Physics and Astronomy Faculty Publications
This work follows Lykins et al. discussion of classic plasma cooling function at low density and solar metallicity. Here, we focus on how the cooling function changes over a wide range of density (nH <1012 cm−3) and metallicity (Z < 30 Z⊙). We find that high densities enhance the ionization of elements such as hydrogen and helium until they reach local thermodynamic equilibrium. By charge transfer, the metallicity changes the ionization of hydrogen when it is partially ionized. We describe the total cooling function as a sum of four parts: those due to H&He, the heavy …
Suppression Of Dielectronic Recombination Due To Finite Density Effects, D. Nikolić, T. W. Gorczyca, K. T. Korista, Gary J. Ferland, N. R. Badnell
Suppression Of Dielectronic Recombination Due To Finite Density Effects, D. Nikolić, T. W. Gorczyca, K. T. Korista, Gary J. Ferland, N. R. Badnell
Physics and Astronomy Faculty Publications
We have developed a general model for determining density-dependent effective dielectronic recombination (DR) rate coefficients in order to explore finite-density effects on the ionization balance of plasmas. Our model consists of multiplying by a suppression factor those highly-accurate total zero-density DR rate coefficients which have been produced from state-of-the-art theoretical calculations and which have been benchmarked by experiment. The suppression factor is based upon earlier detailed collision-radiative calculations which were made for a wide range of ions at various densities and temperatures, but used a simplified treatment of DR. A general suppression formula is then developed as a function of …
Radiative Cooling In Collisionally Ionized And Photoionized Plasmas, Matt Lykins, Gary J. Ferland, Ryan L. Porter, Peter A. M. Van Hoof, R. J. R. Williams, Orly Gnat
Radiative Cooling In Collisionally Ionized And Photoionized Plasmas, Matt Lykins, Gary J. Ferland, Ryan L. Porter, Peter A. M. Van Hoof, R. J. R. Williams, Orly Gnat
Physics and Astronomy Faculty Publications
We discuss recent improvements in the calculation of the radiative cooling in both collisionally ionized and photoionized plasmas. We are extending the spectral simulation code CLOUDY so that as much as possible of the underlying atomic data are taken from external data bases, some created by others and some developed by the CLOUDY team. This paper focuses on recent changes in the treatment of many stages of ionization of iron, and discusses its extensions to other elements. The H- and He-like ions are treated in the isoelectronic approach described previously. Fe II is a special case treated with a large …
Ion-By-Ion Cooling Efficiencies, Orly Gnat, Gary J. Ferland
Ion-By-Ion Cooling Efficiencies, Orly Gnat, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present ion-by-ion cooling efficiencies for low-density gas. We use Cloudy (version 10.00) to estimate the cooling efficiencies for each ion of the first 30 elements (H-Zn) individually. We present results for gas temperatures between 104 and 108 K, assuming low densities and optically thin conditions. When nonequilibrium ionization plays a significant role the ionization states deviate from those that obtain in collisional ionization equilibrium (CIE), and the local cooling efficiency at any given temperature depends on specific nonequilibrium ion fractions. The results presented here allow for an efficient estimate of the total cooling efficiency for any ionic …
"Ultracold" Neutral Plasmas At Room Temperature, N. Heilmann, J. B. Peatross, Scott D. Bergeson
"Ultracold" Neutral Plasmas At Room Temperature, N. Heilmann, J. B. Peatross, Scott D. Bergeson
Faculty Publications
We report a measurement of the electron temperature in a plasma generated by a high-intensity laser focused into a jet of neon. The 15 eV electron temperature is determined using an analytic solution of the plasma equations assuming local thermodynamic equilibrium, initially developed for ultracold neutral plasmas. We show that this analysis method accurately reproduces more sophisticated plasma simulations in our temperature and density range. While our plasma temperatures are far outside the typical "ultracold" regime, the ion temperature is determined by the plasma density through disorder-induced heating just as in ultracold neutral plasma experiments. Based on our results, we …
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy R. Gulley
Modeling Free-Carrier Absorption And Avalanching By Ultrashort Laser Pulses, Jeremy R. Gulley
Faculty and Research Publications
In the past decade it was demonstrated experimentally that negatively-chirped laser pulses can lower the surface LIDT for wide band-gap materials by decreasing the number of photons required for photoionization on the leading edge of the pulse. Similarly, simulations have shown that positively-chirped pulses resulting from selffocusing and self-phase modulation in bulk dielectrics can alter the onset of laser-induced material modifications by increasing the number of photons required for photoionization on the leading edge of the pulse. However, the role of multi-chromatic effects in free-carrier absorption and avalanching has yet to be addressed. In this work a frequency-selective model of …
Density And Temperature Scaling Of Disorder-Induced Heating In Ultracold Plasmas, Scott D. Bergeson, A. Denning, M. Lyon, F. Robicheaux
Density And Temperature Scaling Of Disorder-Induced Heating In Ultracold Plasmas, Scott D. Bergeson, A. Denning, M. Lyon, F. Robicheaux
Faculty Publications
We report measurements and simulations of disorder-induced heating in ultracold neutral plasmas. Fluorescence from plasma ions is excited using a detuned probe laser beam while the plasma relaxes from its initially disordered nonequilibrium state. This method probes the wings of the ion velocity distribution. The simulations yield information on time-evolving plasma parameters that are difficult to measure directly and make it possible to connect the fluorescence signal to the rms velocity distribution. The disorder-induced heating signal can be used to estimate the electron and ion temperatures ~100 ns after the plasma is created. This is particularly interesting for plasmas in …
On The Transition Rate Of The Fe X Red Coronal Line, Gunter Brenner, Jose R. Crespo Lopez-Urrutia, Sven Bernitt, Daniel Fischer, Rainer Ginzel, Kai Uwe Kuhnel, Volkhard Mackel, Paul H. Mokler, Martin C. Simon, Joachim Hermann Ullrich
On The Transition Rate Of The Fe X Red Coronal Line, Gunter Brenner, Jose R. Crespo Lopez-Urrutia, Sven Bernitt, Daniel Fischer, Rainer Ginzel, Kai Uwe Kuhnel, Volkhard Mackel, Paul H. Mokler, Martin C. Simon, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
We present a lifetime measurement of the 3s 23p 5 2 Po 1/2 first excited fine-structure level of the ground state configuration in chlorine-like Fe X, which relaxes to the ground state through a magnetic dipole (M1) transition (the so-called red coronal line) with a wavelength accurately determined to 637.454(1) nm. Moreover, the Zeeman splitting of line was observed. The lifetime of 14.2(2) ms is the most precise one measured in the red wavelength region and agrees well with advanced theoretical predictions and an empirically scaled interpolation based on experimental values from the same isoelectronic sequence.
Light-Particle Single Ionization Of Argon: Influence Of The Projectile Charge Sign, Sebastian Otranto, Ronald E. Olson
Light-Particle Single Ionization Of Argon: Influence Of The Projectile Charge Sign, Sebastian Otranto, Ronald E. Olson
Physics Faculty Research & Creative Works
The ionization of the 3p orbital of argon by incident electrons and positrons is studied by means of the post version of the continuum distorted wave-eikonal initial-state model. Results are presented at both 200 and 500 eV impact energies for conditions amenable to present experiments. Differences in the fully differential cross sections (FDCSs) are analyzed and the influence of the projectile charge sign on the emission dynamics is discussed. The FDCSs are found to display the classic binary plus recoil peak structure at 500 eV, but transition to a more complicated four-lobed structure at the lower impact energy.
Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux
Measurement And Simulation Of Laser-Induced Fluorescence From Nonequilibrium Ultracold Neutral Plasmas, A. Denning, Scott D. Bergeson, F. Robicheaux
Faculty Publications
We report measurements and simulations of laser-induced fluorescence in ultracold neutral plasmas. We focus on the earliest times, when the plasma equilibrium is evolving and before the plasma expands. In the simulation, the ions interact via the Yukawa potential in a small cell with wrapped boundary conditions. We solve the optical Bloch equation for each ion in the simulation as a function of time. Both the simulation and experiment show the initial increase in ion fluorescence, disorder-induced heating, and coherent oscillation of the rms ion velocity. Detailed modeling of the fluorescence signal makes it possible to use fluorescence spectroscopy to …
J=C Production In Square Root Of Snn = 200 Gev Cu + Cu Collisions, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
J=C Production In Square Root Of Snn = 200 Gev Cu + Cu Collisions, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt
Aerospace, Physics, and Space Science Faculty Publications
Yields for J=c production in Cu þ Cu collisions at ffiffiffiffiffiffiffiffi sNN p ¼ 200 GeV have been measured over the rapidity range jyj < 2:2 and compared with results in p þ p and Au þ Au collisions at the same energy. The Cu þ Cu data offer greatly improved precision over existing Au þ Au data for J=c production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d þ Au data describe the Cu þ Cu data up to Npart 50, corresponding to a Bjorken energy density of at least 1:5 GeV=fm3.
Interactions Of Electrons And Rydberg Atoms In Ultra-Cold Plasmas, Cristian Vesa
Interactions Of Electrons And Rydberg Atoms In Ultra-Cold Plasmas, Cristian Vesa
Honors Theses
This thesis discusses an experimental technique for investigating electron temperature control by Rydberg atoms in ultra-cold plasmas. The objective we set ourselves was twofold. Firstly, we sought to gain an insight into the processes whereby the creation of Rydberg atoms within the plasma lengthens the lifetime of the plasma. To this end, we created the plasma using a Littman dye laser and subsequently, at a variable time delay, we excited neutral atoms in the plasma to specific Rydberg states using a narrow bandwidth pulsed dye laser. Secondly, we employed radio-frequency (rf) electric fields to excite electron oscillations within the plasma …