Plasma and Beam Physics Commons^™

Design And Prototyping Of A 400 Mhz Rf-Dipole Crabbing Cavity For The Lhc High-Luminosity Upgrade, S. U. De Silva, J. R. Delayen, H. Park, Z. Li, T. H. Nicol

Physics Faculty Publications

LHC High Luminosity Upgrade is in need of two crabbing systems that deflects the beam in both horizontal and vertical planes. The 400 MHz rf-dipole crabbing cavity system is capable of crabbing the proton beam in both planes. At present we are focusing our efforts on a complete crabbing system in the horizontal plane. Prior to LHC installation the crabbing system will be installed for beam test at SPS. The crabbing system consists of two rf-dipole cavities in the cryomodule. This paper discusses the electromagnetic design and mechanical properties of the rf-dipole crabbing system for SPS beam test.

Progress On The Design Of The Polarized Medium Energy Electron Ion Collider At Jlab, F. Lin, S. A. Bogacz, P. D. Brindza, A Camsonne, E. Daly, Y. S. Derbenev, D. Douglas, R. Ent, D. Gaskell, R. L. Geng, A. Castilla, J. R. Delayen, C. E. Hyde, K. Park

Physics Faculty Publications

The Medium-energy Electron Ion Collider (MEIC) at JLab is designed to provide high luminosity and high polarization needed to reach new frontiers in the exploration of nuclear structure. The luminosity, exceeding 10³³ cm^-2s⁻¹ in a broad range of the center-of-mass (CM) energy and maximum luminosity above 10³⁴ cm^-2s⁻¹, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, ³He) can be easily preserved and …

Effects Of Plasma Processing On Secondary Electron Yield Of Niobium Samples, M. Basovic, S. Popovic, M. Tomovic, L. Vuskovic, A. Samolov, F. Cuckov

Physics Faculty Publications

Impurities deposited on the surface of Nb during both the forming and welding of accelerator cavities add to the imperfections of the sheet metal, which then affects the overall performance of the cavities. This leads to a drop in the Q factor and limits the maximum acceleration gradient achievable per unit length of the cavities. The performance can be improved either by adjusting the fabrication and preparation parameters, or by mitigating the effects of fabrication and preparation techniques used. We have developed the experimental setup to determine Secondary Electron Yield (SEY) from the surface of Nb samples. Our aim is …

Langmuir Probe Instrument Suite For Mesosphere Turbulence Experiment Mission, Adam Blake

Doctoral Dissertations and Master's Theses

The Langmuir probe technique is the predominant in-situ plasma diagnostic technique, and is arguably the only measurement technique that is universally own on every sounding rocket investigation. Earth's mesosphere region (80-120 km) is a host of many dynamic phenomena such as the noctilucent clouds, breaking gravity waves, inversion layers, settlement of mesospheric smoke particles, etc. As such it is critical to have a comprehensive suite of plasma diagnostics that can unambiguously measure various plasma parameters.

This thesis deals with the development and testing of three different Langmuir probe implementations suitable for investigation of the mesosphere which are to be launched …

Nonlinear Dichroism In Back-To-Back Double Ionization Of He By An Intense Elliptically Polarized Few-Cycle Extreme Ultraviolet Pulse, Jean Marcel Ngoko Djiokap, N. L. Manakov, A. V. Meremianin, S. X. Hu, L. B. Madsen, Anthony F. Starace

Anthony F. Starace Publications

Control of double ionization of He by means of the polarization and carrier-envelope phase (CEP) of an intense, few-cycle extreme ultraviolet (XUV) pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schrödinger equation for He interacting with an elliptically polarized XUV pulse. Guided by perturbation theory (PT), we predict the existence of a nonlinear dichroic effect (∝ I^3/2) that is sensitive to the CEP, ellipticity, peak intensity I, and temporal duration of the pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of …

Particle Swarms In Confining Geometries, Eric Robert Boomsma

Open Access Dissertations

The transport of micro- and nano-particles in subsurface fluid deposits is an area of increasing interest due to the rising use of these particles for consumer and industrial purposes. Subsurface particle transport is complicated by the presence of fractures and fracture networks which govern the paths that particles will be able to take. In this thesis, subsurface particle transport will be investigated using particle swarms; collections of hydro-dynamically interacting particles which exhibit group behavior. The effects of fluid viscosity, particle properties, fracture geometry, and fracture aperture on swarm behavior were experimentally investigated. ^ Swarm parameters were examined in time with …

Dropwise Condensation Dynamics In Humid Air, Julian Eduardo Castillo Chaco

Open Access Theses

Dropwise condensation of atmospheric water vapor is important in multiple practical engineering applications. The roles of environmental factors and surface morphology/chemistry on the condensation dynamics need to be better understood to enable efficient water-harvesting, dehumidication, and other psychrometric processes. Systems and surfaces that promote faster condensation rates and self-shedding of condensate droplets could lead to improved mass transfer rates and higher water yields in harvesting applications. The thesis presents the design and construction of an experimental facility that allows visualization of the condensation process as a function of relative humidity. Dropwise condensation experiments are performed on a vertically oriented, hydrophobic …

Optical Spectroscopy And Langmuir Probe Diagnostics Of Microwave Plasma In Synthesis Of Graphene-Based Nanomaterials, Alfredo D. Tuesta

Open Access Dissertations

Along with the revolutionary discovery and development of carbon nanostructures, such as carbon nanotubes and graphitic sheets, has arrived the potential for their application in the fields of medicine, bioscience and engineering due to their exceptional structural, thermal and electrical properties. As roll-to-roll plasma deposition systems begin to provide means for large scale production of these nanodevices, a detailed understanding of the environment responsible for their synthesis is imperative in order to more accurately design and control the growth of carbon nanodevices. To date, the understanding of the chemistry and kinetics that govern the synthesis of carbon nanodevices is only …

Positional Control Of Plasmonic Fields And Electron Emission, Robert Campbell Word, Joseph P. Fitzgerald, Rolf Könenkamp

Physics Faculty Publications and Presentations

We report the positional control of plasmonic fields and electron emission in a continuous gap antenna structure of sub-micron size. We show experimentally that a nanoscale area of plasmon-enhanced electron emission can be motioned by changing the polarization of an exciting optical beam of 800 nm wavelength. Finite-difference calculations are presented to support the experiments and to show that the plasmon-enhanced electric field distribution of the antenna can be motioned precisely and predictively.

Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick J. Cullen, Paula Bourke

Articles

Cold atmospheric plasma (CAP) is produced by ionizing a chosen gas, thereby creating charged and reactive species. The reactive species generated are capable of inducing a range of biomedically relevant interactions including blood coagulation. However, the underlying biochemical processes of plasma-assisted blood coagulation are largely unknown, and data quantifying blood clot formation or the impact of system parameters on the intensity of the blood clot are scarce. In this study, blood coagulation was quantified by measuring hemoglobin absorbance. System parameters of the kINPen plasma jet were investigated and compared, including treatment time, distance from the plasma source and gas flow …

Doube-Pulse Laser-Induced Breakdown Spectroscopy Of Multi-Element Sample Containing Low- And High-Z Analytes, Patrick J. Skrodzki, Jason R. Becker, Prasoon K. Diwakar Ph. D., Sivanandan S. Harilal Ph. D., Ahmed Hassanein Ph. D.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Laser-induced breakdown spectroscopy (LIBS) is a portable, remote, non-invasive analytical technique which effectively distinguishes neutral and ionic species for a range of low- to high-Z elements in a multi-element target. Subsequently, LIBS holds potential in special nuclear material (SNM) sensing and nuclear forensics requiring minimal sample preparation and detecting isotopic shifts which allows for differentiation in SNM (namely U) enrichment levels. Feasible applications include not only nonproliferation and homeland security but also nuclear fuel prospecting and industrial safeguard endorsement. Elements of higher mass with complex atomic structures, such as U, however, result in crowded emission spectra with LIBS, and characteristic …

Double-Pulse Nd:Yag-Co2 Libs Excitation For Bulk And Trace Analytes, Jason R. Becker, Patrick Skrodzki, Prasoon Diwakar, Sivanandan Harilal, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Laser-induced breakdown spectroscopy [LIBS] is a commonly used technique for multi-element analyses for various applications such as space exploration, nuclear forensics, environmental analysis, process monitoring. The advantages of the LIBS technique include robustness, ease of use, field portability, and real-time, non-invasive multi-element analyses. However, in comparison to other lab based analytical techniques, it suffers from low precision and low sensitivity. In order to overcome these drawbacks, various approaches have been used, including double-pulse LIBS [DPLIBS]. Typically, various wavelength combinations of two Nd: yttrium aluminum garnet [YAG] lasers have been used for DPLIBS. However, the use of long wavelength (CO_{2 …}

A Prototype Microwave Cavity Control Circuit For Use In Next Generation Free Electron Laser, Josh Thompson, Peter Neal Barrina, Jiayi Jiang, Joe Frisch, Steve Smith, Daniel Van Winkle

STAR Program Research Presentations

One of the current programs at SLAC National Accelerator Laboratory is the Linac Coherent Light Source, or LCLS. Using the existing hardware of the last third of their linear accelerator (or “linac”), SLAC has created one of the most energetic X-ray free electron lasers (or “FEL”). Since 2009, LCLS has used this FEL to perform a wide range of experiments across all sciences, most notably ultrafast filming at the molecular scale. As requests for beam-time with this laser increases, SLAC is purposing a linac upgrade to better match this demand. This upgrade, named LCLS-II, will replace existing copper radio frequency …

Optimization Of Plasmon Decay Through Scattering And Hot Electron Transfer, Drew Dejarnette

Graduate Theses and Dissertations

Light incident on metal nanoparticles induce localized surface oscillations of conductive electrons, called plasmons, which is a means to control and manipulate light. Excited plasmons decay as either thermal energy as absorbed phonons or electromagnetic energy as scattered photons. An additional decay pathway for plasmons can exist for gold nanoparticles situated on graphene. Excited plasmons can decay directly to the graphene as through hot electron transfer. This dissertation begins by computational analysis of plasmon resonance energy and bandwidth as a function of particle size, shape, and dielectric environment in addition to diffractive coupled in lattices creating a Fano resonance. With …

The Magnetopause: Bringing Space Physics Into A Junior Lab, Jim Crumley, Ari Palczewski,, Stephen Kaster

MapCores Faculty Publications

Undergraduate students often have minimal exposure to many subfields
of physics which are active areas of research. Space physics
is an area that is particularly difficult to expose students to since
it builds off of another area that most undergraduates see little of,
plasma physics. The magnetopause is convenient entry point
into space physics, since it can be modeled as a pressure balance, which is
a concept familiar from introductory physics. We use the Earth's
magnetopause as the basis for a lab for junior physics majors. In
the lab students analyze results from a NASA MHD simulation and
data from …

Below Gap Optical Absorption In Gaas Driven By Intense, Single-Cycle Coherent Transition Radiation, J. Goodfellow, Matthias Fuchs, D. Daranciang, S. Ghimire, F. Chen, H. Loos, D. A. Reis, A. S. Fisher, A. M. Lindenberg

Matthias Fuchs Publications

Single-cycle terahertz fields generated by coherent transition radiation from a relativistic electron beam are used to study the high field optical response of single crystal GaAs. Large amplitude changes in the sub-band-gap optical absorption are induced and probed dynamically by measuring the absorption of a broad-band optical beam generated by transition radiation from the same electron bunch, providing an absolutely synchronized pump and probe geometry. This modification of the optical properties is consistent with strong-field-induced electroabsorption. These processes are pertinent to a wide range of nonlinear terahertz-driven lightmatter interactions anticipated at accelerator-based sources.

Study Of A Generalized Empirical Model For Predicting Pressure Drop For Internal Flows, Tejas Anup Pant

Open Access Theses

A generalized empirical model for estimating the pressure drop across a channel for a given massflow rate is studied through computational fluid dynamics (CFD) simulations. It is observed that for developing laminar and turbulent flow through channels and pipes of arbitrary cross-section, the variation in the pressure drop between any two points in the flow direction with massflow rate can be well approximated by a second degree expression in massflow rate which is referred to as the empirical model in this study. In the first part of this study, a correlation between the pressure gradient and the massflow rate is …

Jet Measurements With Proton-Proton Collisions At 7 Tev In Alice, Kevin Thompson

Physics

The CERN Large Hadron Collider (LHC) is the world's largest and most complex particle accelerator, with several experiments making discoveries at the frontiers of particle and nuclear physics. The ALICE experiment at the LHC explores the nature of the early Universe through relativistic nuclear collisions. The properties of the "quark-gluon" plasma of subatomic particles created can be investigated with particle jets, which are produced in the earliest moments of the collision. This paper will provide an overview of the analysis of particle jets in 7 TeV proton-proton collisions, which forms the baseline for understanding jet production in collisions of heavy …

X-Ray Second Harmonic Generation, S. Shwartz, Matthias Fuchs, J. B. Hastings, Y. Inubushi, T. Ishikawa, T. Katayama, D. A. Reis, T. Sato, K. Tono, M. Yabashi, S. Yudovich, S. E. Harris

Matthias Fuchs Publications

We report clear experimental evidence for second harmonic generation at hard x-ray wavelengths. Using a 1.7 Å pumping beam generated by a free electron laser, we observe second harmonic generation in diamond. The generated second harmonic is of order 10 times the background radiation, scales quadratically with pump pulse energy, and is generated over a narrow phase-matching condition. Of importance for future experiments, our results indicate that it is possible to observe nonlinear x-ray processes in crystals at pump intensities exceeding 10¹⁶ W/cm².

Feasibility Analysis Of Large Length-Scale Thermocapillary Flow Experiment For The International Space Station, Samantha Jean Alberts

Open Access Theses

The investigation of microgravity fluid dynamics emerged out of necessity with the advent of space exploration. In particular, capillary research took a leap forward in the 1960s with regards to liquid settling and interfacial dynamics. Due to inherent temperature variations in large spacecraft liquid systems, such as fuel tanks, forces develop on gas-liquid interfaces which induce thermocapillary flows. To date, thermocapillary flows have been studied in small, idealized research geometries usually under terrestrial conditions. The 1 to 3m lengths in current and future large tanks and hardware are designed based on hardware rather than research, which leaves spaceflight systems designers …