Plasma and Beam Physics Commons^™

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 …

Simulation Studies On The Interactions Of Electron Beam With Wastewater, X. Li, S. Wang, Helmut Baumgart, G. Ciovati, F. Hannon

Electrical & Computer Engineering Faculty Publications

The manufactured chemical pollutants, like 1,4 dioxane and PFAS (per- and polyfluroralkyl substances), found in the underground water and/or drinking water are challenging to be removed or biodegraded. Energetic electrons are capable of mediating and removing them. This paper utilizes FLUKA code to evaluate the beam-wastewater interaction effects with different energy, space and divergence distributions of the electron beam. With 8 MeV average energy, the electron beam exits from a 0.0127 cm thick titanium window, travels through a 4.3 cm distance air and a second 0.0127 cm thick stainless water container window with 2.43 cm radius, and finally is injected …

Transient Behavior Of Drift And Ionization In Atmospheric Pressure Nitrogen Discharge, S. K. Dhali

Electrical & Computer Engineering Faculty Publications

The fluid models are frequently used to describe a non-thermal plasma such as a streamer discharge. The required electron transport data and rate coefficients for the fluid model are parametrized using the local field approximation (LFA) in first order models and the local-mean-energy approximation (LMEA) in second order models. We performed Monte Carlo simulations in Nitrogen gas with step changes in the E/N (reduced electric field) to study the behavior of the transport properties in the transient phase. During the transient phase of the simulation, we extract the instantaneous electron mean energy, which is different from the steady state mean …

The Resistive Barrier Discharge: A Brief Review Of The Device And Its Biomedical Applications, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

This paper reviews the principles behind the design and operation of the resistive barrier discharge, a low temperature plasma source that operates at atmospheric pressure. One of the advantages of this plasma source is that it can be operated using either DC or AC high voltages. Plasma generated by the resistive barrier discharge has been used to efficiently inactivate pathogenic microorganisms and to destroy cancer cells. These biomedical applications of low temperature plasma are of great interest because in recent times bacteria developed increased resistance to antibiotics and because present cancer therapies often are accompanied by serious side effects. Low …

High Voltage Design And Evaluation Of Wien Filters For The Cebaf 200 Kev Injector Upgrade, Gabriel Palacios-Serrano, Helmut Baumgart, C. Hernández-García, P. Adderley, J. Benesch, D. Bullard, J. Grames, A. Hofler, D. Machie, M. Poelker, M. Stutzman, R. Suleiman

Electrical & Computer Engineering Faculty Publications

High-energy nuclear physics experiments at the Jefferson Lab Continuous Electron Beam Accelerator Facility (CEBAF) require highly spin-polarization electron beams, produced from strained super-lattice GaAs photocathodes, activated to negative electron affinity in a photogun operating at 130 kV dc. A pair of Wien filter spin rotators in the injector defines the orientation of the electron beam polarization at the end station target. An upgrade of the CEBAF injector to better support the upcoming MOLLER experiment requires increasing the electron beam energy to 200 keV, to reduce unwanted helicity correlated intensity and position systematics and provide precise control of the polarization orientation. …

Impacts Of Laboratory Vibrations And Laser Flicker Noise On Digital Holography, Douglas E. Thornton, Mark F. Spencer, Christopher A. Rice, Glen P. Perram

Faculty Publications

In this paper, we experimentally demonstrate the impacts of laboratory vibrations and laser flicker noise on digital holography (DH). Specifically, we measure both the vibration efficiency and the coherence efficiency of our DH system at various focal-plane array integration times and path-length differences between the signal and reference. These efficiencies, in practice, contribute to the overall mixing efficiency, which is a measure for how well the detected signal and reference interfere. The results show that when the integration time is ≤1ms, the laboratory vibrations are negligible with a vibration efficiency of 100%; however, when the integration time equals 100 ms, …

Optimizing Llrf Parameters In The Electron-Ion Collider, William M. Bjorndahl

Physics

To improve particle interaction in the future Electron-Ion Collider (EIC), we investigated different feedback implementations to control the accelerating voltage and examined the power and beam phase for each instance. Using MATLAB, we studied three feedback mechanisms: Direct, One Turn, and Feedforward. Enacting feedforward yielded the best performance. To minimize the klystron power consumption, we analyzed different Low-Level Radio Frequency (LLRF) parameters such as detuning. Combining theory and simulated results, we found the optimal detuning value that minimizes klystron power consumption.

Experimental Testing Of A 3d-Printed Metamaterial Slow Wave Structure For High Power Microwave Generation, Antonio B. De Alleluia

Electrical and Computer Engineering ETDs

A metamaterial (MTM) high power microwave (HPM) vacuum electron device (VED) was developed using 3D printing technology. The specific geometric pattern of the source can produce both negative permittivity and permeability to interact with a relativistic electron beam. The electron beam is generated using a pulsed electron accelerator with a maximum energy of 700 keV and lasting approximately 16 ns. The design of this novel VED consists of a circular waveguide loaded with complementary split-ring resonators in a linear periodic arrangement in which the relativistic beam travels guided by a magnetic field. The electrons interact with the MTM producing electromagnetic …

Measurement Of Electron Density And Temperature From Laser-Induced Nitrogen Plasma At Elevated Pressure (1–6 Bar), Ashwin P. Rao, Mark Gragston, Anil K. Patnaik, Paul S. Hsu, Michael B. Shattan

Faculty Publications

Laser-induced plasmas experience Stark broadening and shifts of spectral lines carrying spectral signatures of plasma properties. In this paper, we report time-resolved Stark broadening measurements of a nitrogen triplet emission line at 1–6 bar ambient pressure in a pure nitrogen cell. Electron densities are calculated using the Stark broadening for different pressure conditions, which are shown to linearly increase with pressure. Additionally, using a Boltzmann fit for the triplet, the electron temperature is calculated and shown to decrease with increasing pressure. The rate of plasma cooling is observed to increase with pressure. The reported Stark broadening based plasma diagnostics in …

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 …

Polarization Properties Of Airy And Ince-Gaussian Laser Beams, Sean Michael Nomoto

Graduate Theses and Dissertations

The description of polarization states of laser light as linear, circular polarization within the paraxial scalar wave approximation is adequate for most applications. However, this description falls short when considering laser light as an electromagnetic wave satisfying Maxwell's equations. An electric field with a constant unit vector for direction of the field and a space dependent complex scalar amplitude in the paraxial wave approximation does not satisfy Maxwell equations which, in general, requires all three Cartesian components of electric and magnetic fields associated for a nonzero laser beam to be nonzero.

Physical observation of passing a linearly polarized laser through …

Effects Of Pulse Width On He Plasma Jets In Contact With Water Evaluated By Oh(A-X) Emission And Ohaq Production, Shutong Song, Esin B. Sözer, Chunqi Jiang

Bioelectrics Publications

Nanosecond pulsed helium plasma jets impinging on water produce hydroxyl radicals both in gas- and liquid-phase. In this study, the effects of pulse width on a repetitively pulsed plasma jet in contact with water are evaluated via OH(A-X) emission and OH_aq production in water for various pulse widths ranging from 200 to 5000 ns. The maximal energy efficiency of OH(A-X) emission is obtained for pulse widths of 600-800 ns whereas the maximal efficiency of OH_aq production is at 200 ns. Temporally-resolved emission spectroscopy shows that more than 40% of OH(A-X) emission is produced during the first 200 ns …

Optical Response Analysis Of Thz Photoconductive Antenna Using Comsol Multiphysics, Jose Isaac Santos Batista

Electrical Engineering Undergraduate Honors Theses

A THz photoconductive antenna consists of antenna pads laid over a photoconductive substrate. These types of antennas are excited through the application of an optical pump (laser), which generates carriers inside the semiconductor. The acceleration and recombination of these carriers produce photocurrent that excites the antenna and generates THz pulse. This thesis focuses on analyzing the optical response of a photoconductive antenna, which consist of the interaction of the incident electric field of a laser pump with the radiating device. It develops the amplitude modulation process of a plane wave of light into a laser pump. It also takes into …

The Effect Of Tube Geometry On The Chiral Plasma, S. Jin, D. Zou, X. Lu, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

A chiral plasma plume has recently been reported inside a circular quartz tube without the use of an external magnetic field. It is believed that the quartz tube plays an important role in the formation of the chiral plasma plume. In this paper, to better understand how this interesting structure is generated, the effect of the tube geometry on the chiral plasma is investigated. First, the effect of the thickness of the tube wall on the chiral plasma is investigated. It is interesting to find that a too thin or too thick tube wall is not favorable for generating the …

Carbon Multicharged Ion Generation From Laser-Spark Ion Source, Md. Mahmudur Rahman, Oguzhan Balki, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Multicharged carbon ions are generated by using a laser-assisted spark-discharge ion source. A Q-switched Nd:YAG laser pulse (1064 nm, 7 ns, ≤ 4.5 × 10⁹ W/cm²) focused onto the surface of a glassy carbon target results in its ablation. The spark-discharge (∼1.2 J energy, ∼1 µs duration) is initiated along the direction of the plume propagation between the target surface and a grounded mesh that is parallel to the target surface. Ions emitted from the laser-spark plasma are detected by their time-of-flight using a Faraday cup. The ion energy-to-charge ratio is analyzed by a three-mesh retarding field …

Compact -300 Kv Dc Inverted Insulator Photogun With Biased Anode And Alkali-Antimonide Photocathode, C. Hernandez-Garcia, P. Adderley, B. Bullard, J. Benesch, J. Grames, J. Gubeli, F. Hannon, J. Hansknecht, J. Jordan, R. Kazimi, G. A. Krafft, M. A. Mamun, M. Poelker, M. L. Stutzman, R. Suleiman, M. Tiefenback, Y. Wang, S. Zhang, H. Baumgart, G. Palacios-Serrano, S. Wijethunga, J. Yoskowitz, C. A. Valerio Lizarraga, R. Montoya Soto, A. Canales Ramos

Electrical & Computer Engineering Faculty Publications

This contribution describes the latest milestones of a multiyear program to build and operate a compact −300  kV dc high voltage photogun with inverted insulator geometry and alkali-antimonide photocathodes. Photocathode thermal emittance measurements and quantum efficiency charge lifetime measurements at average current up to 4.5 mA are presented, as well as an innovative implementation of ion generation and tracking simulations to explain the benefits of a biased anode to repel beam line ions from the anode-cathode gap, to dramatically improve the operating lifetime of the photogun and eliminate the occurrence of micro-arc discharges.

Ignition Of A Plasma Discharge Inside An Electrodeless Chamber: Methods And Characteristics, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

In this paper the generation and diagnostics of a reduced pressure (300 mTorr to 3 Torr) plasma generated inside an electrodeless containment vessel/chamber are presented. The plasma is ignited by a guided ionization wave emitted by a low temperature pulsed plasma jet. The diagnostics techniques include Intensified Charge Coupled Device (ICCD) imaging, emission spectroscopy, and Langmuir probe. The reduced-pressure discharge parameters measured are the magnitude of the electric field, the plasma electron number density and temperature, and discharge expansion speed.

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) …

Effects Of Fabrication Errors On The Focusing Performance Of A Sector Metalens, S. S. Stafeev, A. G. Nalimov, Liam O’Faolain, M. V. Kotlyar

Cappa Publications

Using e-beam lithography, a 16-sector spiral metalens was fabricated in an amorphous silicon, capable of converting linearly polarized incident light into an azimuthally polarized optical vortex. When illuminated by a 633-nm linearly polarized laser beam, the metalens generated a near-surface subwavelength focal spot equal to 0.75 of the incident wavelength at full-width of half-maximum intensity. The focusing performance of the spiral metalens was numerically shown to be sensitive to the deviation of the factual microrelief from the calculated height. For the designed microrelief height, a circularly polarized incident beam was focused into a bright ring with a reverse energy flow …

Generation Of Large-Volume Diffuse Plasma By An External Ionization Wave From A Single-Electrode Plasma Jet, Seyed Hamid Razavi Barzoki

Electrical & Computer Engineering Theses & Dissertations

A non-thermal transient diffuse plasma can be generated remotely in a nonconductive reduced pressure chamber by an external guided fast ionization wave (FIW). We found that an atmospheric-pressure low-temperature plasma jet (APPJ) can be a source of FIW which transfers an enhanced electric field at the wave front across a reduced pressure Pyrex glass chamber with no electrical connection to the chamber. Here, we studied the formation and propagation of the APPJ plasma, the interaction of atmospheric-pressure guided FIW with a dielectric surface which forms the wall of the reduced-pressure system, and the formation and propagation of the reduce-pressure FIW …

Plasmonic Grating Geometrics And Wavelength-Dependent Focus Depth In Infrared Detectors, Patrick R. Kennedy

Theses and Dissertations

The objective for this research is to determine a relationship between plasmonic grating geometries and the wavelength-dependent focus depth. This research is focused on enhancing the signal collected by infrared detectors by using a metal grating as a planar lens to focus light in the detecting region of the substrate. This can be used to maintain a thinner absorbing region and possibly to create multi-color imaging in a single pixel. Simulations demonstrate that the plasmonic lens is capable of creating a wavelength dependent focus spot.

Plasma Medicine: A Brief Introduction, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

This mini review is to introduce the readers of Plasma to the field of plasma medicine. This is a multidisciplinary field of research at the intersection of physics, engineering, biology and medicine. Plasma medicine is only about two decades old, but the research community active in this emerging field has grown tremendously in the last few years. Today, research is being conducted on a number of applications including wound healing and cancer treatment. Although a lot of knowledge has been created and our understanding of the fundamental mechanisms that play important roles in the interaction between low temperature plasma and …

Aluminum Multicharged Ion Generation From Femtosecond Laser Plasma, Md. Haider A. Shaim, Frederick Guy Wilson, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Aluminum multicharged ion generation from femtosecond laser ablation is studied. A Ti:sapphire laser (wavelength 800 nm, pulse width ∼100 fs, and maximum laser fluence of 7.6 J/cm²) is used. Ion yield and energy distribution of each charge state are measured. A linear relationship between the ion charge state and the equivalent acceleration energy of the individual ion species is observed and is attributed to the presence of an electric field within the plasma-vacuum boundary that accelerates the ions. The ion energy distribution follows a shifted Coulomb-Boltzmann distribution. For Al¹⁺ and Al²⁺, the ion energy distributions …

Low Temperature Plasma For The Treatment Of Epithelial Cancer Cells, Soheila Mohades

Electrical & Computer Engineering Theses & Dissertations

Biomedical applications of low temperature plasmas (LTP) may lead to a paradigm shift in treating various diseases by conducting fundamental research on the effects of LTP on cells, tissues, organisms (plants, insects, and microorganisms). This is a rapidly growing interdisciplinary research field that involves engineering, physics, life sciences, and chemistry to find novel solutions for urgent medical needs. Effects of different LTP sources have shown the anti-tumor properties of plasma exposure; however, there are still many unknowns about the interaction of plasma with eukaryotic cells which must be elucidated in order to evaluate the practical potential of plasma in cancer …

Experimental Investigation Of Plasma Dynamics In Jets And Bubbles Using A Compact Coaxial Plasma Gun In A Background Magnetized Plasma, Yue Zhang

Electrical and Computer Engineering ETDs

Numerous solar and astrophysical observations of jet- and bubble-like plasma structures exhibit morphological similarities, suggesting that there may be common plasma physics at work in the formation and evolution processes of these structures at different system scales. The ideal magnetohydrodynamics (MHD) provide the necessary theoretical basis for employing laboratory experiments to investigate key physical processes in nonlinear astrophysical and solar systems, especially when magnetic fields are present.

A coaxial magnetized plasma gun has been designed, installed, and operated in the HelCat linear device at the University of New Mexico. In Region I, a current-driven plasma jet is formed. The plasma …

Comparison Between Electropositive And Electronegative Cold Atmospheric-Pressure Plasmas: A Modelling Study, Ding X. Liu, Jia F. Li, Ai J. Yang, Xiao H. Wang, Ming Z. Rong, Michael G. Kong

Bioelectrics Publications

Cold atmospheric-pressure He + N₂ and He + O₂ plasmas are chosen as the representatives for electropositive and electronegative plasmas, of which the discharge characteristics are studied and then compared to each other by fluid models. As the increase of the impurity (N₂ or O₂) fraction from 0 to 10%, for He + N₂ plasmas the electron density and ion density increase, the spatiotemporal distributions of electron density, ion density, electron temperature and electron generation rate change a little. On contrast, for He + O₂ plasmas the electron density decreases, the ion density …

Intensity Control Of Dielectric Barrier Discharge Filaments, Matthew Crawford Paliwoda

Masters Theses

"When operated in a filamentary mode, a volume dielectric barrier discharge (DBD) is known to produce patterned plasma structures. These structures are currently being explored for reconfigurable metamaterial applications. In this work the presence and intensity of a single filament, within an array of filaments, was controlled by adjusting the voltage to that filament's individual needle electrode. The current, voltage, and time-averaged normalized light intensity were measured while varying the voltage of the needle through a self-biasing resistance. For a 7.5 kV, 3.2 kHz DBD in air, the needle-controlled filament intensity varies from that of the surrounding filaments to zero …

Evaluation Of The Effects Of A Plasma Activated Medium On Cancer Cells, S. Mohades, M. Laroussi, J. Sears, N. Barekzi, H. Razavi

Electrical & Computer Engineering Faculty Publications

The interaction of low temperature plasma with liquids is a relevant topic of study to the field of plasma medicine. This is because cells and tissues are normally surrounded or covered by biological fluids. Therefore, the chemistry induced by the plasma in the aqueous state becomes crucial and usually dictates the biological outcomes. This process became even more important after the discovery that plasma activated media can be useful in killing various cancer cell lines. Here, we report on the measurements of concentrations of hydrogen peroxide, a species known to have strong biological effects, produced by application of plasma to …

Spark Discharge Coupled Laser Multicharged Ion Source, Md. Haider A. Shaim, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

A spark discharge is coupled to a laser multicharged ion source to enhance ion generation. The laser plasma triggers a spark discharge with electrodes located in front of the ablated target. For an aluminum target, the spark discharge results in significant enhancement in the generation of multicharged ions along with higher charge states than observed with the laser source alone. When a Nd:YAG laser pulse (wavelength 1064 nm, pulse width 7.4 ns, pulse energy 72 mJ, laser spot area on target 0.0024 cm²) is used, the total multicharged ions detected by a Faraday cup is 1.0 nC with …

Reconfigurable Solid-State Dye-Doped Polymer Ring Resonator Lasers, Hengky Chandrahalim, Xudong Fan

Faculty Publications

This paper presents wavelength configurable on-chip solid-state ring lasers fabricated by a single-mask standard lithography. The single- and coupled-ring resonator hosts were fabricated on a fused-silica wafer and filled with 3,3′-Diethyloxacarbocyanine iodide (CY3), Rhodamine 6G (R6G) and 3,3′-Diethylthiadicarbocyanine iodide (CY5)-doped polymer as the reconfigurable gain media. The recorded lasing threshold was ~220 nJ/mm² per pulse for the single-ring resonator laser with R6G, marking the lowest threshold shown by solid-state dye-doped polymer lasers fabricated with a standard lithography process on a chip. A single-mode lasing from a coupled-ring resonator system with the lasing threshold of ~360 nJ/mm² per pulse …