Atomic Layer Epitaxy of Aluminum Nitride: Unraveling the Connection between Hydrogen Plasma and Carbon Contamination.

PubMed

Erwin, Steven C; Lyons, John L

2018-06-13

Atomistic control over the growth of semiconductor thin films, such as aluminum nitride, is a long-sought goal in materials physics. One promising approach is plasma-assisted atomic layer epitaxy, in which separate reactant precursors are employed to grow the cation and anion layers in alternating deposition steps. The use of a plasma during the growth-most often a hydrogen plasma-is now routine and generally considered critical, but the precise role of the plasma is not well-understood. We propose a theoretical atomistic model and elucidate its consequences using analytical rate equations, density functional theory, and kinetic Monte Carlo statistical simulations. We show that using a plasma has two important consequences, one beneficial and one detrimental. The plasma produces atomic hydrogen in the gas phase, which is important for removing methyl radicals left over from the aluminum precursor molecules. However, atomic hydrogen also leads to atomic carbon on the surface and, moreover, opens a channel for trapping these carbon atoms as impurities in the subsurface region, where they remain as unwanted contaminants. Understanding this dual role leads us to propose a solution for the carbon contamination problem which leaves the main benefit of the plasma largely unaffected.

Is the bulk mode conversion important in high density helicon plasma?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro

2016-06-15

In a high-density helicon plasma production process, a contribution of Trivelpiece-Gould (TG) wave for surface power deposition is widely accepted. The TG wave can be excited either due to an abrupt density gradient near the plasma edge (surface conversion) or due to linear mode conversion from the helicon wave in a density gradient in the bulk region (bulk mode conversion). By numerically solving the boundary value problem of linear coupling between the helicon and the TG waves in a background with density gradient, we show that the efficiency of the bulk mode conversion strongly depends on the dissipation included inmore » the plasma, and the bulk mode conversion is important when the dissipation is small. Also, by performing FDTD simulation, we show the time evolution of energy flux associated with the helicon and the TG waves.« less

Magnetic Reconnection in Extreme Astrophysical Environments

NASA Astrophysics Data System (ADS)

Uzdensky, Dmitri A.

2011-10-01

Magnetic reconnection is a fundamental plasma physics process in which ideal-MHD's frozen-in constraints are broken and the magnetic field topology is dramatically re-arranged, which often leads to a violent release of the free magnetic energy. Most of the magnetic reconnection research done to date has been motivated by the applications to systems such as the solar corona, Earth's magnetosphere, and magnetic confinement devices for thermonuclear fusion. These environments have relatively low energy densities and the plasma is adequately described as a mixture of equal numbers of electrons and ions and where the dissipated magnetic energy always stays with the plasma. In contrast, in this paper I would like to introduce a different, new direction of research—reconnection in high energy density radiative plasmas, in which photons play as important a role as electrons and ions; in particular, in which radiation pressure and radiative cooling become dominant factors in the pressure and energy balance. This research is motivated in part by rapid theoretical and experimental advances in High Energy Density Physics, and in part by several important problems in modern high-energy astrophysics. I first discuss some astrophysical examples of high-energy-density reconnection and then identify the key physical processes that distinguish them from traditional reconnection. Among the most important of these processes are: special-relativistic effects; radiative effects (radiative cooling, radiation pressure, and radiative resistivity); and, at the most extreme end—QED effects, including pair creation. The most notable among the astrophysical applications are situations involving magnetar-strength fields (1014-1015 G, exceeding the quantum critical field B ∗≃4×1013 G). The most important examples are giant flares in soft gamma repeaters (SGRs) and magnetic models of the central engines and relativistic jets of Gamma Ray Bursts (GRBs). The magnetic energy density in these environments is so high that, when it is suddenly released, the plasma is heated to ultra-relativistic temperatures. As a result, electron-positron pairs are created in copious quantities, dressing the reconnection layer in an optically thick pair coat, thereby trapping the photons. The plasma pressure inside the layer is then dominated by the combined radiation and pair pressure. At the same time, the timescale for radiation diffusion across the layer may, under some conditions, still be shorter than the global (along the layer) Alfvén transit time, and hence radiative cooling starts to dominate the thermodynamics of the problem. The reconnection problem then becomes essentially a radiative transfer problem. In addition, the high pair density makes the reconnection layer highly collisional, independent of the upstream plasma density, and hence radiative resistive MHD applies. The presence of all these processes calls for a substantial revision of our traditional physical picture of reconnection when applied to these environments and thus opens a new frontier in reconnection research.

Role of grain size and particle velocity distribution in secondary electron emission in space plasmas

NASA Technical Reports Server (NTRS)

Chow, V. W.; Mendis, D. A.; Rosenberg, M.

1993-01-01

By virtue of being generally immersed in a plasma environment, cosmic dust is necessarily electrically charged. The fact that secondary emission plays an important role in determining the equilibrium grain potential has long been recognized, but the fact that the grain size plays a crucial role in this equilibrium potential, when secondary emission is important, has not been widely appreciated. Using both conducting and insulating spherical grains of various sizes and also both Maxwellian and generalized Lorentzian plasmas (which are believed to represent certain space plasmas), we have made a detailed study of this problem. In general, we find that the secondary emission yield delta increases with decreasing size and becomes very large for grains whose dimensions are comparable to the primary electron penetration depth, such as in the case of the very small grains observed at comet Halley and inferred in the interstellar medium. Moreover, we observed that delta is larger for insulators and equilibrium potentials are generally more positive when the plasma has a broad non-Maxwellian tail. Interestingly, we find that for thermal energies that are expected in several cosmic regions, grains of different sizes can have opposite charge, the smaller ones being positive while the larger ones are negative. This may have important consequences for grain accretion in polydisperse dusty space plasmas.

Current and Perspective Applications of Dense Plasma Focus Devices

NASA Astrophysics Data System (ADS)

Gribkov, V. A.

2008-04-01

Dense Plasma Focus (DPF) devices' applications, which are intended to support the main-stream large-scale nuclear fusion programs (NFP) from one side (both in fundamental problems of Dense Magnetized Plasma physics and in its engineering issues) as well as elaborated for an immediate use in a number of fields from the other one, are described. In the first direction such problems as self-generated magnetic fields, implosion stability of plasma shells having a high aspect ratio, etc. are important for the Inertial Confinement Fusion (ICF) programs (e.g. as NIF), whereas different problems of current disruption phenomenon, plasma turbulence, mechanisms of generation of fast particles and neutrons in magnetized plasmas are of great interest for the large devices of the Magnetic Plasma Confinement—MPC (e.g. as ITER). In a sphere of the engineering problems of NFP it is shown that in particular the radiation material sciences have DPF as a very efficient tool for radiation tests of prospect materials and for improvement of their characteristics. In the field of broad-band current applications some results obtained in the fields of radiation material sciences, radiobiology, nuclear medicine, express Neutron Activation Analysis (including a single-shot interrogation of hidden illegal objects), dynamic non-destructive quality control, X-Ray microlithography and micromachining, and micro-radiography are presented. As the examples of the potential future applications it is proposed to use DPF as a powerful high-flux neutron source to generate very powerful pulses of neutrons in the nanosecond (ns) range of its duration for innovative experiments in nuclear physics, for the goals of radiation treatment of malignant tumors, for neutron tests of materials of the first wall, blankets and NFP device's constructions (with fluences up to 1 dpa per a year term), and ns pulses of fast electrons, neutrons and hard X-Rays for brachytherapy.

One-dimensional hybrid model of plasma-solid interaction in argon plasma at higher pressures

NASA Astrophysics Data System (ADS)

Jelínek, P.; Hrach, R.

2007-04-01

One of problems important in the present plasma science is the surface treatment of materials at higher pressures, including the atmospheric pressure plasma. The theoretical analysis of processes in such plasmas is difficult, because the theories derived for collisionless or slightly collisional plasma lose their validity at medium and high pressures, therefore the methods of computational physics are being widely used. There are two basic ways, how to model the physical processes taking place during the interaction of plasma with immersed solids. The first technique is the particle approach, the second one is called the fluid modelling. Both these approaches have their limitations-small efficiency of particle modelling and limited accuracy of fluid models. In computer modelling is endeavoured to use advantages by combination of these two approaches, this combination is named hybrid modelling. In our work one-dimensional hybrid model of plasma-solid interaction has been developed for an electropositive plasma at higher pressures. We have used hybrid model for this problem only as the test for our next applications, e.g. pulsed discharge, RF discharge, etc. The hybrid model consists of a combined molecular dynamics-Monte Carlo model for fast electrons and fluid model for slow electrons and positive argon ions. The latter model also contains Poisson's equation, to obtain a self-consistent electric field distribution. The derived results include the spatial distributions of electric potential, concentrations and fluxes of individual charged species near the substrate for various pressures and for various probe voltage bias.

Implementation of a plasma-neutral model in NIMROD

NASA Astrophysics Data System (ADS)

Taheri, S.; Shumlak, U.; King, J. R.

2016-10-01

Interaction between plasma fluid and neutral species is of great importance in the edge region of magnetically confined fusion plasmas. The presence of neutrals can have beneficial effects such as fueling burning plasmas and quenching the disruptions in tokamaks, as well as deleterious effects like depositing high energy particles on the vessel wall. The behavior of edge plasmas in magnetically confined systems has been investigated using computational approaches that utilize the fluid description for the plasma and Monte Carlo transport for neutrals. In this research a reacting plasma-neutral model is implemented in NIMROD to study the interaction between plasma and neutral fluids. This model, developed by E. T. Meier and U. Shumlak, combines a single-fluid magnetohydrodynamic (MHD) plasma model with a gas dynamic neutral fluid model which accounts for electron-impact ionization, radiative recombination, and resonant charge exchange. Incorporating this model into NIMROD allows the study of the interaction between neutrals and plasma in a variety of plasma science problems. An accelerated plasma moving through a neutral gas background in a coaxial electrode configuration is modeled, and the results are compared with previous calculations from the HiFi code.

Effect of Trapped Ions on Shielding and Floating Potential of a Dust Grain in a Plasma

NASA Astrophysics Data System (ADS)

Lampe, Martin; Ganguli, Gurudas; Joyce, Glenn; Gavrishchaka, Valeriy

2001-10-01

The problem of electrostatic shielding around a small spherical collector immersed in plasma, and the related problem of electron and ion flow to the collector, date to the origins of plasma physics. Beginning with Mott-Smith and Langmuir (1926), calculations have typically neglected collisions, on the grounds that the mean free path is long compared to shielding length scales, i.e. the Debye length. However, investigators beginning with Bernstein and Rabinowitz (1959) have known that negative-energy trapped ions, created by occasional collisions, might be important. We present an analytic calculation of the density of trapped and untrapped ions, self-consistent with the potential. Under typical conditions for dust grains immersed in a discharge plasma, trapped ions dominate the shielding cloud in steady state, even in the limit of very long mean free path. As a result the shielded potential is different from the results of orbital motion limited theory. Collisions also greatly increase the ion current to the collector, thereby decreasing the floating potential and the grain charge by a factor as large as two to three.

A Laboratory Astrophysical Jet to Study Canonical Flux Tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

You, Setthivoine

Understanding the interaction between plasma flows and magnetic fields remains a fundamental problem in plasma physics, with important applications to astrophysics, fusion energy, and advanced space propulsion. For example, flows are of primary importance in astrophysical jets even if it is not fully understood how jets become so long without becoming unstable. Theories for the origin of magnetic fields in the cosmos rely on flowing charged fluids that should generate magnetic fields, yet this remains to be demonstrated experimentally. Fusion energy reactors can be made smaller with flows that improve stability and confinement. Advanced space propulsion could be more efficientmore » with collimated and stable plasma flows through magnetic nozzles but must eventually detach from the nozzle. In all these cases, there appears to be a spontaneous emergence of flowing and/or magnetic structures, suggesting a form of self-organization in plasmas. Beyond satisfying simple intellectual curiosity, understanding plasma self-organization could enable the development of methods to control plasma structures for fusion energy, space propulsion, and other applications. The research project has therefore built a theory and an experiment to investigate the interaction between magnetic fields and plasma flows. The theory is called canonical field theory for short, and the experiment is called Mochi after a rice cake filled with surprising, yet delicious fillings.« less

Reconstruction of magnetic configurations in W7-X using artificial neural networks

NASA Astrophysics Data System (ADS)

Böckenhoff, Daniel; Blatzheim, Marko; Hölbe, Hauke; Niemann, Holger; Pisano, Fabio; Labahn, Roger; Pedersen, Thomas Sunn; The W7-X Team

2018-05-01

It is demonstrated that artificial neural networks can be used to accurately and efficiently predict details of the magnetic topology at the plasma edge of the Wendelstein 7-X stellarator, based on simulated as well as measured heat load patterns onto plasma-facing components observed with infrared cameras. The connection between heat load patterns and the magnetic topology is a challenging regression problem, but one that suits artificial neural networks well. The use of a neural network makes it feasible to analyze and control the plasma exhaust in real-time, an important goal for Wendelstein 7-X, and for magnetic confinement fusion research in general.

Green technology for conversion of renewable hydrocarbon based on plasma-catalytic approach

NASA Astrophysics Data System (ADS)

Fedirchyk, Igor; Nedybaliuk, Oleg; Chernyak, Valeriy; Demchina, Valentina

2016-09-01

The ability to convert renewable biomass into fuels and chemicals is one of the most important steps on our path to green technology and sustainable development. However, the complex composition of biomass poses a major problem for established conversion technologies. The high temperature of thermochemical biomass conversion often leads to the appearance of undesirable byproducts and waste. The catalytic conversion has reduced yield and feedstock range. Plasma-catalytic reforming technology opens a new path for biomass conversion by replacing feedstock-specific catalysts with free radicals generated in the plasma. We studied the plasma-catalytic conversion of several renewable hydrocarbons using the air plasma created by rotating gliding discharge. We found that plasma-catalytic hydrocarbon conversion can be conducted at significantly lower temperatures (500 K) than during the thermochemical ( 1000 K) and catalytic (800 K) conversion. By using gas chromatography, we determined conversion products and found that conversion efficiency of plasma-catalytic conversion reaches over 85%. We used obtained data to determine the energy yield of hydrogen in case of plasma-catalytic reforming of ethanol and compared it with other plasma-based hydrogen-generating systems.

Spectroscopic studies of non-thermal plasma jet at atmospheric pressure formed in low-current nonsteady-state plasmatron for biomedical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demkin, V. P.; Melnichuk, S. V.; Demkin, O. V.

The optical and electrophysical characteristics of the nonequilibrium low-temperature plasma formed by a low-current nonsteady-state plasmatron are experimentally investigated in the present work. It is demonstrated that experimental data on the optical diagnostics of the plasma jet can provide a basis for the construction of a self-consistent physical and mathematical plasma model and for the creation of plasma sources with controllable electrophysical parameters intended for the generation of the required concentration of active particles. Results of spectroscopic diagnostics of plasma of the low-current nonsteady-state plasmatron confirm that the given source is efficient for the generation of charged particles and short-wavelengthmore » radiation—important plasma components for biomedical problems of an increase in the efficiency of treatment of biological tissues by charged particles. Measurement of the spatial distribution of the plasma jet potential by the probe method has demonstrated that a negative space charge is formed in the plasma jet possibly due to the formation of electronegative oxygen ions.« less

The segmented non-uniform dielectric module design for uniformity control of plasma profile in a capacitively coupled plasma chamber

NASA Astrophysics Data System (ADS)

Xia, Huanxiong; Xiang, Dong; Yang, Wang; Mou, Peng

2014-12-01

Low-temperature plasma technique is one of the critical techniques in IC manufacturing process, such as etching and thin-film deposition, and the uniformity greatly impacts the process quality, so the design for the plasma uniformity control is very important but difficult. It is hard to finely and flexibly regulate the spatial distribution of the plasma in the chamber via controlling the discharge parameters or modifying the structure in zero-dimensional space, and it just can adjust the overall level of the process factors. In the view of this problem, a segmented non-uniform dielectric module design solution is proposed for the regulation of the plasma profile in a CCP chamber. The solution achieves refined and flexible regulation of the plasma profile in the radial direction via configuring the relative permittivity and the width of each segment. In order to solve this design problem, a novel simulation-based auto-design approach is proposed, which can automatically design the positional sequence with multi independent variables to make the output target profile in the parameterized simulation model approximate the one that users preset. This approach employs an idea of quasi-closed-loop control system, and works in an iterative mode. It starts from initial values of the design variable sequences, and predicts better sequences via the feedback of the profile error between the output target profile and the expected one. It never stops until the profile error is narrowed in the preset tolerance.

Plasma levels of serotonin, gastrointestinal symptoms,and sleep problems in children with autism.

PubMed

Kheirouri, Sorayya; Kalejahi, Parinaz; Noorazar, Seyyed Gholamreza

2016-12-20

Autism is a neurodevelopmental disorder identified with higher frequency of serotonin abnormalities and gastrointestinal (GI) and sleep problems. This study aimed to evaluate the plasma levels of serotonin, GI symptoms, and sleep problems, and their relationship with autism severity in children with autism. Thirty-five children with autism and 31 healthy subjects were studied. GI problems, sleep disorders, and severity of disorder were assessed. Plasma serotonin was determined using ELISA. There was no significant association between GI problems and autism severity, but a significant positive correlation was seen between different indicators of sleep disorder and severity of autism. Plasma levels of serotonin were significantly higher in autistic children and a significant negative correlation was observed between plasma levels of serotonin and autism severity (r = -0.39, P = 0.02). Elevated plasma serotonin in autistic children and its negative correlation with disease severity may indicate involvement of the neurotransmitter in the neurophysiologic mechanism of autism.

Poincaré analysis of wave motion in ultrarelativistic electron-ion plasmas.

PubMed

Lehmann, G; Spatschek, K H

2011-03-01

Based on a relativistic Maxwell-fluid description, the existence of ultrarelativistic laser-induced periodic waves in an electron-ion plasma is investigated. Within a one-dimensional propagation geometry nonlinear coupling of the electromagnetic and electrostatic components occurs that makes the fourth-order problem nonintegrable. A Hamiltonian description is derived, and the manifolds of periodic solutions are studied by Poincaré section plots. The influence of ion motion is investigated in different intensity regimes. For ultrarelativistic laser intensities the phase-space structures change significantly compared to the weakly relativistic case. Ion motion becomes very important such that finally electron-ion plasmas in the far-ultrarelativistic regime behave similarly to electron-positron plasmas. The characteristic new types of periodic solutions of the system are identified and discussed.

High voltage space plasma interactions. [charging the solar power satellites

NASA Technical Reports Server (NTRS)

Mccoy, J. E.

1980-01-01

Two primary problems resulted from plasma interactions; one of concern to operations in geosynchronous orbit (GEO), the other in low orbits (LEO). The two problems are not the same. Spacecraft charging has become widely recognized as a problem, particularly for communications satellites operating in GEO. The very thin thermal plasmas at GEO are insufficient to bleed off voltage buildups due to higher energy charged particle radiation collected on outer surfaces. Resulting differential charging/discharging causes electrical transients, spurious command signals and possible direct overload damage. An extensive NASA/Air Force program has been underway for several years to address this problem. At lower altitudes, the denser plasmas of the plasmasphere/ionosphere provide sufficient thermal current to limit such charging to a few volts or less. Unfortunately, these thermal plasma currents which solve the GEO spacecraft charging problem can become large enough to cause just the opposite problem in LEO.

Gene Transfection Method Using Atmospheric Pressure Dielectric-Barrier Discharge Plasmas

NASA Astrophysics Data System (ADS)

Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

2013-09-01

Gene transfection which is the process of deliberately introducing nucleic acids into cells is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure dielectric-barrier discharge (AP-DBD) plasmas. AP-DBD He plasmas are irradiated to the living cell covered with genes. Preliminarily, we use fluorescent dye YOYO-1 instead of the genes and use LIVE/DEAD Stain for cell viability test, and we analyze the transfection efficiency and cell viability under the various conditions. It is clarified that the transfection efficiency is strongly dependence on the plasma irradiation time and cell viability rates is high rates (>90%) regardless of long plasma irradiation time. These results suggest that ROS (Reactive Oxygen Species) and electric field generated by the plasma affect the gene transfection. In addition to this (the plasma irradiation time) dependency, we now investigate the effect of the plasma irradiation under the various conditions.

Summary of the discussion meeting on alpha particle theory problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sigmar, D.J.

1988-04-01

The agenda of the meeting (consisting of {approximately}20 theoreticians and 2 experimentalists working on single {alpha}-particle effects and diagnostics) was to discuss the spectrum of relevant {alpha}-theory problems as it is presently understood, its impact on ignited plasma performance, and possible paths to stabilization. The purpose was to expose existing efforts to peer review and to focus on the most important topics. Twenty-one talks were given which are summarized. Overall, there emerged a consensus about the existence of robust (MHD-like) collective oscillations affecting both the {alpha}-species and the bulk plasma. In addition, improved calculations of classical {alpha}-phenomena due to driftmore » orbits and collisions and {alpha}-RF interactions were discussed. An overview of topics covered is given in the attached conference program.« less

Effect of Trapped Ions on Shielding of a Charged Spherical Object in a Plasma

NASA Astrophysics Data System (ADS)

Lampe, Martin; Ganguli, Gurudas; Joyce, Glenn; Gavrishchaka, Valeriy

2001-04-01

The problem of electrostatic shielding around a small spherical collector immersed in plasma, and the related problem of electron and ion flow to the collector, date to the origins of plasma physics. Beginning with Langmuir[1], all calculations have neglected collisions, on the grounds that the mean free path is long compared to shielding length scales, i.e. the Debye length. However, investigators beginning with Bernstein and Rabinowitz[2] have known that negative-energy trapped ions, created by occasional collisions, might be important. We present an analytic calculation of the density of trapped and untrapped ions, self-consistent with a calculation of the potential. We show that under typical conditions for dust grains immersed in a discharge plasma, trapped ions dominate the shielding cloud in steady state, even in the limit of very long mean free path. As a result the shielded potential is quite different from the Debye form or the results of orbital motion limited theory. Collisions also modify the ion current to the grain, but to a lesser extent. [1]H. Mott-Smith and I. Langmuir, Phys. Rev. 28, 27 (1926). [2]I. Bernstein and I. Rabinowitz, Phys. Fluids 2,112(1959).

Review of Leading Approaches for Mitigating Hypersonic Vehicle Communications Blackout and a Method of Ceramic Particulate Injection Via Cathode Spot Arcs for Blackout Mitigation

NASA Technical Reports Server (NTRS)

Gillman, Eric D.; Foster, John E.; Blankson, Isaiah M.

2010-01-01

Vehicles flying at hypersonic velocities within the atmosphere become enveloped in a "plasma sheath" that prevents radio communication, telemetry, and most importantly, GPS signal reception for navigation. This radio "blackout" period has been a problem since the dawn of the manned space program and was an especially significant hindrance during the days of the Apollo missions. An appropriate mitigation method must allow for spacecraft to ground control and ground control to spacecraft communications through the reentry plasma sheath. Many mitigation techniques have been proposed, including but not limited to, aerodynamic shaping, magnetic windows, and liquid injection. The research performed on these mitigation techniques over the years will be reviewed and summarized, along with the advantages and obstacles that each technique will need to overcome to be practically implemented. A unique approach for mitigating the blackout communications problem is presented herein along with research results associated with this method. The novel method involves the injection of ceramic metal-oxide particulate into a simulated reentry plasma to quench the reentry plasma. Injection of the solid ceramic particulates is achieved by entrainment within induced, energetic cathode spot flows.

Copper deficiency in the preterm infant of very low birthweight. Four cases and a reference range for plasma copper.

PubMed Central

Sutton, A M; Harvie, A; Cockburn, F; Farquharson, J; Logan, R W

1985-01-01

Four preterm infants of very low birthweight (less than 1500 g) developed signs of copper deficiency between age 8 and 10 weeks. All had required prolonged ventilatory support, parenteral nutrition, and nasojejunal feeding. The clinical features, which included osteoporosis, oedema, anaemia, neutropenia, and late apnoea improved when the oral copper intake was increased. Diagnosis was made more difficult because a suitable reference range for plasma copper was not available. Serial measurements of plasma copper in 39 preterm infants who had no important medical problems were used to produce a reference range for plasma copper from 30 weeks' gestation to term plus seven weeks. This information will aid recognition of hypocupraemia in the very low birthweight infant who is particularly at risk of copper deficiency. PMID:4026360

Diagnostics of recombining laser plasma parameters based on He-like ion resonance lines intensity ratios

NASA Astrophysics Data System (ADS)

Ryazantsev, S. N.; Skobelev, I. Yu; Faenov, A. Ya; Pikuz, T. A.; Grum-Grzhimailo, A. N.; Pikuz, S. A.

2016-11-01

While the plasma created by powerful laser expands from the target surface it becomes overcooled, i.e. recombining one. Improving of diagnostic methods applicable for such plasma is rather important problem in laboratory astrophysics nowadays because laser produced jets are fully scalable to young stellar objects. Such scaling is possible because of the plasma hydrodynamic equations invariance under some transformations. In this paper it is shown that relative intensities of the resonance transitions in He-like ions can be used to measure the parameters of recombining plasma. Intensity of the spectral lines corresponding to these transitions is sensitive to the density in the range of 1016-1020 cm-3 while the temperature ranges from 10 to 100 eV for ions with nuclear charge Zn ∼ 10. Calculations were carried out for F VIII ion and allowed to determine parameters of plasma jets created by nanosecond laser system ELFIE (Ecole Polytechnique, France) for astrophysical phenomenon modelling. Obtained dependencies are quite universal and can be used for any recombining plasma containing He-like fluorine ions.

Dynamic Contraction of the Positive Column of a Self-Sustained Glow Discharge in Molecular Gas Flow

NASA Astrophysics Data System (ADS)

Shneider, Mikhail

2014-10-01

Contraction of the gas discharge, when current contracts from a significant volume of weakly ionized plasma into a thin arc channel, was attracted attention of scientists for more than a century. Studies of the contraction (also called constriction) mechanisms, besides carrying interesting science, are of practical importance, especially when contraction should be prevented. A set of time-dependent two-dimensional equations for the non-equilibrium weakly-ionized nitrogen/ air plasma is formulated. The process is described by a set of time-dependent continuity equations for the electrons, positive and negative ions; gas and vibrational temperature; by taking into account the convective heat and plasma losses by the transverse flux. Transition from the uniform to contracted state was analyzed. It was shown that such transition experiences a hysteresis, and that the critical current of the transition increases when the pressure (gas density) drops. Possible coexistence of the contracted and uniform state of the plasma in the discharge where the current flows along the density gradient of the background gas was discussed. In this talk the problems related to the dynamic contraction of the current channel inside a quasineutral positive column of a self-sustained glow discharge in molecular gas in a rectangular duct with convection cooling will be discussed. Study presented in this talk was stimulated by the fact that there are large number of experiments on the dynamic contraction of a glow discharge in nitrogen and air flows and a many of possible applications. Similar processes play a role in the powerful gas-discharge lasers. In addition, the problem of dynamic contraction in the large volume of non-equilibrium weakly ionized plasma is closely related to the problem of streamer to leader transitions in lightning and blue jets.

High voltage plasma sheath analysis related to TSS-1

NASA Technical Reports Server (NTRS)

Sheldon, John W.

1990-01-01

On the first mission of the Tethered Satellite System (TSS-1), a 1.8 m diameter spherical satellite will be deployed a distance of 20 km above the Space Shuttle Orbiter on an insulated conducting tether. The satellite will be held at electric potentials up to 5000 volts positive with respect to the ambient plasma. Due to the passage of the conducting tether through the Earth's magnetic field, an electromagnetic field (EMF) will be created, driving electrons down the tether to the Orbiter, out through an electron gun into the ionosphere and back into the positive-biased satellite. The main problem addressed here is the current-voltage characteristics of the ionospheric interaction with the satellite. The first problem is that while the satellite will be capable of measuring charged particle flow to the surface at several locations, the detectors have a limited range of acceptance angle. The second problem is that the angle of incidence of the incoming electrons will have to be relative to the local normal. This will be important in order to predict the magnitude of the detectable current at each detector location so the detector gain can be pre-set to the correct range. The plasma sheath was analyzed mathematically, and subroutines were written to solve relevant finite element, Taylor-Vlasov, and Poisson equations.

Long pulse operation of the Kamaboko negative ion source on the MANTIS test bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tramham, R.; Jacquot, C.; Riz, D.

1998-08-20

Advanced Tokamak concepts and steady state plasma scenarios require external plasma heating and current drive for extended time periods. This poses several problems for the neutral beam injection systems that are currently in use. The power loading of the ion source and accelerator are especially problematic. The Kamaboko negative ion source, a small scale model of the ITER arc source, is being prepared for extended operation of deuterium beams for up to 1000 seconds. The operating conditions of the plasma grid prove to be important for reducing electron power loading of the accelerator. Operation of deuterium beams for extended periodsmore » also poses radiation safety risks which must be addressed.« less

Effects of large-angle Coulomb collisions on inertial confinement fusion plasmas.

PubMed

Turrell, A E; Sherlock, M; Rose, S J

2014-06-20

Large-angle Coulomb collisions affect the rates of energy and momentum exchange in a plasma, and it is expected that their effects will be important in many plasmas of current research interest, including in inertial confinement fusion. Their inclusion is a long-standing problem, and the first fully self-consistent method for calculating their effects is presented. This method is applied to "burn" in the hot fuel in inertial confinement fusion capsules and finds that the yield increases due to an increase in the rate of temperature equilibration between electrons and ions which is not predicted by small-angle collision theories. The equilibration rate increases are 50%-100% for number densities of 10(30)  m(-3) and temperatures around 1 keV.

Differential Influence of Components Resulting from Atmospheric-Pressure Plasma on Integrin Expression of Human HaCaT Keratinocytes

PubMed Central

Haertel, Beate; Straßenburg, Susanne; Wende, Kristian; von Woedtke, Thomas

2013-01-01

Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100 ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells. PMID:23936843

Cutoff Probe for Tokamak SOL Measurement

NASA Astrophysics Data System (ADS)

Na, Byung-Keun; You, Kwang-Ho; Kim, Dae-Woong; You, Shin-Jae; Kim, Jung-Hyung; Chang, Hong-Young

2013-09-01

Since a cutoff probe was developed, there have been a lot of improvements in methodology and analysis for low temperature plasmas. However, in order to apply the cutoff probe to the Tokamak scrape-off layer (SOL), three important issues should be solved - speed, thermal protection, and short-distance (a few mm) wave propagation in magnetized plasmas. In this presentation, the improvement of cutoff probe for Tokamak is shown. The above problems can be solved using the following methods: (a) the cutoff probe can be used with short impulse of a few nano-seconds for speed improvement. (b) Ceramic covers were used for thermal protection. (c) In magnetized plasmas, the cutoff peak can be analyzed using circuit modeling and CST Microwave studio. To verify the proposed methods, the cutoff probe was applied to a Helicon plasma, and the results were compared to laser Thomson scattering results. Based on the result in the Helicon plasma, the cutoff probe will be applied to far-SOL region at the KSTAR 2013 campaign, and SOL region at the later campaign.

Effects of a reentry plasma sheath on the beam pointing properties of an array antenna

NASA Astrophysics Data System (ADS)

Bai, Bowen; Liu, Yanming; Lin, Xiaofang; Li, Xiaoping

2018-03-01

The reduction in the gain of an on-board antenna caused by a reentry plasma sheath is an important effect that contributes to the reentry "blackout" problem. Using phased array antenna and beamforming technology could provide higher gain and an increase in the communication signal intensity. The attenuation and phase delay of the electromagnetic (EM) waves transmitting through the plasma sheath are direction-dependent, and the radiation pattern of the phased array antenna is affected, leading to a deviation in the beam pointing. In this paper, the far-field pattern of a planar array antenna covered by a plasma sheath is deduced analytically by considering both refraction and mutual coupling effects. A comparison between the analytic results and the results from an electromagnetic simulation is carried out. The effect of the plasma sheath on the radiation pattern and the beam pointing errors of the phased array antenna is studied systematically, and the derived results could provide useful information for the correction of pointing errors.

Physical Processes in the MAGO/MFT Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garanin, Sergey F; Reinovsky, Robert E.

2015-03-23

The Monograph is devoted to theoretical discussion of the physical effects, which are most significant for the alternative approach to the problem of controlled thermonuclear fusion (CTF): the MAGO/MTF approach. The book includes the description of the approach, its difference from the major CTF systems—magnetic confinement and inertial confinement systems. General physical methods of the processes simulation in this approach are considered, including plasma transport phenomena and radiation, and the theory of transverse collisionless shock waves, the surface discharges theory, important for such kind of research. Different flows and magneto-hydrodynamic plasma instabilities occurring in the frames of this approach aremore » also considered. In virtue of the general physical essence of the considered phenomena the presented results are applicable to a wide range of plasma physics and hydrodynamics processes. The book is intended for the plasma physics and hydrodynamics specialists, post-graduate students, and senior students-physicists.« less

Methodology and Results of Mathematical Modelling of Complex Technological Processes

NASA Astrophysics Data System (ADS)

Mokrova, Nataliya V.

2018-03-01

The methodology of system analysis allows us to draw a mathematical model of the complex technological process. The mathematical description of the plasma-chemical process was proposed. The importance the quenching rate and initial temperature decrease time was confirmed for producing the maximum amount of the target product. The results of numerical integration of the system of differential equations can be used to describe reagent concentrations, plasma jet rate and temperature in order to achieve optimal mode of hardening. Such models are applicable both for solving control problems and predicting future states of sophisticated technological systems.

Electron Bernstein waves in spherical torus plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saveliev, A. N.

2006-11-30

Propagation and absorption of the electron Bernstein waves (EBWs) in spherical tokamaks (STs) have been intensively discussed in recent years because the EBWs coupled with an externally launched electromagnetic beam seem to be the only opportunity for microwave plasma heating and current drive in the electron cyclotron (EC) frequency range in the STs. The whole problem of the electron Bernstein heating and current drive (EBWHCD) in spherical plasmas is naturally divided into three major parts: coupling of incident electromagnetic waves (EMWs) to the EBWs near the upper hybrid resonance (UHR) surface, propagation and absorption of the EBWs in the plasmamore » interior and generation of noninductive current driven by the EBWs. The present paper is a brief survey of the most important theoretical and numerical results on the issue of EBWs.« less

Effects of ionization and ion loss on dust ion-acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

NASA Astrophysics Data System (ADS)

Mayout, Saliha; Gougam, Leila Ait; Tribeche, Mouloud

2016-03-01

The combined effects of ionization, ion loss, and electron suprathermality on dust ion-acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg-de Vries (dK-dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK-dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the dust ion-acoustic solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

Effects of ionization and ion loss on dust ion- acoustic solitary waves in a collisional dusty plasma with suprathermal electrons

NASA Astrophysics Data System (ADS)

Tribeche, Mouloud; Mayout, Saliha

2016-07-01

The combined effects of ionization, ion loss and electron suprathermality on dust ion- acoustic solitary waves in a collisional dusty plasma are examined. Carrying out a small but finite amplitude analysis, a damped Korteweg- de Vries (dK-- dV) equation is derived. The damping term decreases with the increase of the spectral index and saturates for Maxwellian electrons. Choosing typical plasma parameters, the analytical approximate solution of the dK- dV equation is numerically analyzed. We first neglect the ionization and ion loss effects and account only for collisions to estimate the relative importance between these damping terms which can act concurrently. Interestingly, we found that as the suprathermal character of the electrons becomes important, the strength of the collisions related dissipation becomes more important and causes the DIA solitary wave amplitude to decay more rapidly. Moreover, the collisional damping may largely prevail over the ionization and ion loss related damping. The latter becomes more effective as the electrons evolve far away from their thermal equilibrium. Our results complement and provide new insights into previously published work on this problem.

Magnetic Reconnection in Extreme Astrophysical Environments

NASA Astrophysics Data System (ADS)

Uzdensky, Dmitri

Magnetic reconnection is a fundamental plasma physics process of breaking ideal-MHD's frozen-in constraints on magnetic field connectivity and of dramatic rearranging of the magnetic topol-ogy, which often leads to a violent release of the free magnetic energy. Reconnection has long been acknowledged to be of great importance in laboratory plasma physics (magnetic fusion) and in space and solar physics (responsible for solar flares and magnetospheric substorms). In addition, its importance in Astrophysics has been increasingly recognized in recent years. However, due to a great diversity of astrophysical environments, the fundamental physics of astrophysical magnetic reconnection can be quite different from that of the traditional recon-nection encountered in the solar system. In particular, environments like the solar corona and the magnetosphere are characterized by relatively low energy densities, where the plasma is ad-equately described as a mixture of electrons and ions whose numbers are conserved and where the dissipated magnetic energy basically stays with the plasma. In contrast, in many high-energy astrophysical phenomena the energy density is so large that photons play as important a role as electrons and ions and, in particular, radiation pressure and radiative cooling become dominant. In this talk I focus on the most extreme case of high-energy-density astrophysical reconnec-tion — reconnection of magnetar-strength (1014 - 1015 Gauss) magnetic fields, important for giant flares in soft-gamma repeaters (SGRs), and for rapid magnetic energy release in either the central engines or in the relativistic jets of Gamma Ray Bursts (GRBs). I outline the key relevant physical processes and present a new theoretical picture of magnetic reconnection in these environments. The corresponding magnetic energy density is so enormous that, when suddenly released, it inevitably heats the plasma to relativistic temperatures, resulting in co-pious production of electron-positron pairs. The pairs make the reconnection layer optically thick, efficiently trapping gamma-ray photons and ensuring a local thermodynamic equilibrium between the radiation and the plasma. The plasma pressure inside the layer is then dominated by the radiation and pair pressure. At the same time, the timescale for radiation diffusion across the layer may still be much shorter than the global Alfven transit time along the layer, and hence the effects of radiative cooling on the thermodynamics of the layer need to be taken into account. In other words, the reconnection problem in this regime necessarily becomes a radiative transfer problem. In addition, the extremely high pair density, set by the local ther-modynamic equilibrium essentially independently of the upstream plasma density, can make the reconnection layer highly collisional, thereby justifying the use of resistive MHD (with Spitzer and Compton resistivities). The presence of all these processes calls for a substantial revision of our traditional physical picture of reconnection when applied to these environments. I will de-scribe how the corresponding new theory of reconnection of magnetar-strength magnetic fields ought to be constructed and will conclude by discussing its observational consequences and the prospects for future research.

Fluid moments of the nonlinear Landau collision operator

DOE PAGES

Hirvijoki, E.; Lingam, M.; Pfefferle, D.; ...

2016-08-09

An important problem in plasma physics is the lack of an accurate and complete description of Coulomb collisions in associated fluid models. To shed light on the problem, this Letter introduces an integral identity involving the multivariate Hermite tensor polynomials and presents a method for computing exact expressions for the fluid moments of the nonlinear Landau collision operator. In conclusion, the proposed methodology provides a systematic and rigorous means of extending the validity of fluid models that have an underlying inverse-square force particle dynamics to arbitrary collisionality and flow.

Response of plasma facing components in Tokamaks due to intense energy deposition using Particle-In-Cell (PIC) methods

NASA Astrophysics Data System (ADS)

Genco, Filippo

Damage to plasma-facing components (PFC) due to various plasma instabilities is still a major concern for the successful development of fusion energy and represents a significant research obstacle in the community. It is of great importance to fully understand the behavior and lifetime expectancy of PFC under both low energy cycles during normal events and highly energetic events as disruptions, Edge-Localized Modes (ELM), Vertical Displacement Events (VDE), and Run-away electron (RE). The consequences of these high energetic dumps with energy fluxes ranging from 10 MJ/m2 up to 200 MJ/m 2 applied in very short periods (0.1 to 5 ms) can be catastrophic both for safety and economic reasons. Those phenomena can cause a) large temperature increase in the target material b) consequent melting, evaporation and erosion losses due to the extremely high heat fluxes c) possible structural damage and permanent degradation of the entire bulk material with probable burnout of the coolant tubes; d) plasma contamination, transport of target material into the chamber far from where it was originally picked. The modeling of off-normal events such as Disruptions and ELMs requires the simultaneous solution of three main problems along time: a) the heat transfer in the plasma facing component b) the interaction of the produced vapor from the surface with the incoming plasma particles c) the transport of the radiation produced in the vapor-plasma cloud. In addition the moving boundaries problem has to be considered and solved at the material surface. Considering the carbon divertor as target, the moving boundaries are two since for the given conditions, carbon doesn't melt: the plasma front and the moving eroded material surface. The current solution methods for this problem use finite differences and moving coordinates system based on the Crank-Nicholson method and Alternating Directions Implicit Method (ADI). Currently Particle-In-Cell (PIC) methods are widely used for solving complex dynamics problems involving distorted plasma hydrodynamic problems and plasma physics. The PIC method solves the hydrodynamic equations solving all field equations tracking at the same time "sample particles" or pseudo-particles (representative of the much more numerous real ones) as the move under the influence of diffusion or magnetic force. The superior behavior of the PIC techniques over the more classical Lagrangian finite difference methods stands in the fact that detailed information about the particles are available at all times as well as mass and momentum transport values are constantly provided. This allows with a relative small number of particles to well describe the behavior of plasma even in presence of highly distorted flows without losing accuracy. The radiation transport equation is solved at each time step calculating for each cell the opacity and emissivity coefficients. Photon radiation continuum and line fluxes are also calculated per the entire domain and provide useful information for the entire energetic calculation of the system which in the end provides the total values of erosion and lifetime of the target material. In this thesis, a new code named HEIGHTS-PIC code has been created and modified using a new approach of the PIC technique to solve the three physics problems involved integrating each of them as a continuum providing insight on the plasma behavior, evolution along time and physical understanding of the very complex phenomena taking place. The results produced with the models are compared with the well-known and benchmarked HEIGHTS package and also with existing experimental results especially produced in Russia at the TRINITI facility. Comparisons with LASER experiments are also discussed.

Theoretical investigation of EM wave generation and radiation in the ULF, ELF, and VLF bands by the electrodynamic orbiting tether

NASA Technical Reports Server (NTRS)

Estes, Robert D.; Grossi, Mario D.

1989-01-01

The problem of electromagnetic wave generation by an electrodynamic tethered satellite system is important both for the ordinary operation of such systems and for their possible application as orbiting transmitters. The tether's ionospheric circuit closure problem is closely linked with the propagation of charge-carrying electromagnetic wave packets away from the tethered system. Work is reported which represents a step towards a solution to the problem that takes into account the effects of boundaries and of vertical variations in plasma density, collision frequencies, and ion species. The theory of Alfen wave packet generation by an electrodynamic tethered system in an infinite plasma medium is reviewed, and brief summary of previous work on the problem is given. The consequences of the presence of the boundaries and the vertical nonuniformity are then examined. One of the most significant new features to emerge when ion-neutral collisions are taken into account is the coupling of the Alfven waves to the fast magnetosonic wave. This latter wave is important, as it may be confined by vertical variations in the Alfven speed to a sort of leaky ionospheric wave guide, the resonances of which could be of great importance to the signal received on the Earth's surface. The infinite medium solution for this case where the (uniform) geomagnetic field makes an arbitrary angle with the vertical is taken as the incident wave-packet. Even without a full solution, a number of conclusions can be drawn, the most important of which may be that the electromagnetic field associated with the operation of a steady-current tethered system will probably be too weak to detect on the Earth's surface, even for large tethered currents. This is due to the total reflection of the incident wave at the atmospheric boundary and the inability of a steady-current tethered system to excite the ionospheric wave-guide. An outline of the approach to the numerical problem is given. The use of numerical integrations and boundary conditions consistent with a conducting Earth is proposed to obtain the solution for the horizontal electromagnetic field components at the boundary of the ionosphere with the atmospheric cavity.

Velocity Space Degrees of Freedom of Plasma Fluctuations

NASA Astrophysics Data System (ADS)

Mattingly, Sean

2017-10-01

Small scale wave modes are becoming more important in plasma physics. Examples include turbulent cascades in the solar wind, the energetics of fusion plasma electrostatic turbulence and transport, and low temperature basic plasma physics experiments. In order to improve our understanding of these modes, I present an advance in experimental plasma diagnostics and use it to show the first measurement of a plasma ion velocity-space cross-correlation matrix. From this matrix I determine the eigenmodes of fluctuations on the ion distribution function as a function of frequency. I also determine the relative strengths of these modes - these are the velocity space degrees of freedom of plasma fluctuations. This measurement can detect the aforementioned smaller scale modes in plasmas through a localized measurement. The locality of this measurement means that it may be applied to plasmas in which a single - point velocity sensitive diagnostic is available and multipoint measurements may be difficult. Examples include in situ measurements of space plasmas, fusion plasmas, trapped plasmas, and laser cooled plasmas. This fact, combined with the new perspective it can give on small scale plasma fluctuations, means it may be used to further research on the above cited subjects. Much work remains on fully understanding this measurement. This measurement opens a velocity space interpretation of small scale plasma wave modes, and understanding this perspective from theory requires the application or invention of new mathematical tools. I discuss open problems to follow up on, which include questions from experimental, theoretical, and instrumentation perspectives. NSF-DOE Program Grant DE-FG02-99ER54543.

The quantum pinch effect in semiconducting quantum wires: A bird’s-eye view

NASA Astrophysics Data System (ADS)

Kushwaha, Manvir S.

2016-01-01

Those who measure success with culmination do not seem to be aware that life is a journey not a destination. This spirit is best reflected in the unceasing failures in efforts for solving the problem of controlled thermonuclear fusion for even the simplest pinches for over decades; and the nature keeps us challenging with examples. However, these efforts have permitted researchers the obtention of a dense plasma with a lifetime that, albeit short, is sufficient to study the physics of the pinch effect, to create methods of plasma diagnostics, and to develop a modern theory of plasma processes. Most importantly, they have impregnated the solid state plasmas, particularly the electron-hole plasmas in semiconductors, which do not suffer from the issues related with the confinement and which have demonstrated their potential not only for the fundamental physics but also for the device physics. Here, we report on a two-component, cylindrical, quasi-one-dimensional quantum plasma subjected to a radial confining harmonic potential and an applied magnetic field in the symmetric gauge. It is demonstrated that such a system, as can be realized in semiconducting quantum wires, offers an excellent medium for observing the quantum pinch effect at low temperatures. An exact analytical solution of the problem allows us to make significant observations: Surprisingly, in contrast to the classical pinch effect, the particle density as well as the current density display a determinable maximum before attaining a minimum at the surface of the quantum wire. The effect will persist as long as the equilibrium pair density is sustained. Therefore, the technological promise that emerges is the route to the precise electronic devices that will control the particle beams at the nanoscale.

Charging of the Van Allen Probes: Theory and Simulations

NASA Astrophysics Data System (ADS)

Delzanno, G. L.; Meierbachtol, C.; Svyatskiy, D.; Denton, M.

2017-12-01

The electrical charging of spacecraft has been a known problem since the beginning of the space age. Its consequences can vary from moderate (single event upsets) to catastrophic (total loss of the spacecraft) depending on a variety of causes, some of which could be related to the surrounding plasma environment, including emission processes from the spacecraft surface. Because of its complexity and cost, this problem is typically studied using numerical simulations. However, inherent unknowns in both plasma parameters and spacecraft material properties can lead to inaccurate predictions of overall spacecraft charging levels. The goal of this work is to identify and study the driving causes and necessary parameters for particular spacecraft charging events on the Van Allen Probes (VAP) spacecraft. This is achieved by making use of plasma theory, numerical simulations, and on-board data. First, we present a simple theoretical spacecraft charging model, which assumes a spherical spacecraft geometry and is based upon the classical orbital-motion-limited approximation. Some input parameters to the model (such as the warm plasma distribution function) are taken directly from on-board VAP data, while other parameters are either varied parametrically to assess their impact on the spacecraft potential, or constrained through spacecraft charging data and statistical techniques. Second, a fully self-consistent numerical simulation is performed by supplying these parameters to CPIC, a particle-in-cell code specifically designed for studying plasma-material interactions. CPIC simulations remove some of the assumptions of the theoretical model and also capture the influence of the full geometry of the spacecraft. The CPIC numerical simulation results will be presented and compared with on-board VAP data. This work will set the foundation for our eventual goal of importing the full plasma environment from the LANL-developed SHIELDS framework into CPIC, in order to more accurately predict spacecraft charging.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasouli, C.; Abbasi Davani, F.; Rokrok, B.

Plasma confinement using external magnetic field is one of the successful ways leading to the controlled nuclear fusion. Development and validation of the solution process for plasma equilibrium in the experimental toroidal fusion devices is the main subject of this work. Solution of the nonlinear 2D stationary problem as posed by the Grad-Shafranov equation gives quantitative information about plasma equilibrium inside the vacuum chamber of hot fusion devices. This study suggests solving plasma equilibrium equation which is essential in toroidal nuclear fusion devices, using a mesh-free method in a condition that the plasma boundary is unknown. The Grad-Shafranov equation hasmore » been solved numerically by the point interpolation collocation mesh-free method. Important features of this approach include truly mesh free, simple mathematical relationships between points and acceptable precision in comparison with the parametric results. The calculation process has been done by using the regular and irregular nodal distribution and support domains with different points. The relative error between numerical and analytical solution is discussed for several test examples such as small size Damavand tokamak, ITER-like equilibrium, NSTX-like equilibrium, and typical Spheromak.« less

Towards large-scale plasma-assisted synthesis of nanowires

NASA Astrophysics Data System (ADS)

Cvelbar, U.

2011-05-01

Large quantities of nanomaterials, e.g. nanowires (NWs), are needed to overcome the high market price of nanomaterials and make nanotechnology widely available for general public use and applications to numerous devices. Therefore, there is an enormous need for new methods or routes for synthesis of those nanostructures. Here plasma technologies for synthesis of NWs, nanotubes, nanoparticles or other nanostructures might play a key role in the near future. This paper presents a three-dimensional problem of large-scale synthesis connected with the time, quantity and quality of nanostructures. Herein, four different plasma methods for NW synthesis are presented in contrast to other methods, e.g. thermal processes, chemical vapour deposition or wet chemical processes. The pros and cons are discussed in detail for the case of two metal oxides: iron oxide and zinc oxide NWs, which are important for many applications.

Topological constraints and the existence of force-free fields

NASA Technical Reports Server (NTRS)

Antiochos, S. K.

1986-01-01

A fundamental problem in plasma theory is the question of the existence of MHD equilibria. The issue of topological constraints is of crucial importance for the problem of the existence of equilibria. Heuristic methods are used to discuss the coronal wrapping pattern. It is concluded that for a given set of footpoint positions the wrapping pattern in the corona is completely fixed. The topological constraints are included in the boundary conditions on the Euler potentials and impost no additional restrictions on possible equilibria. Although this does not prove that equilibria always exist, it does show that the force-free problem is not overdetermined and that existence of equilibria is still an open question.

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. Brooks; A.H. Reiman; G.H. Neilson

High-beta, low-aspect-ratio (compact) stellarators are promising solutions to the problem of developing a magnetic plasma configuration for magnetic fusion power plants that can be sustained in steady-state without disrupting. These concepts combine features of stellarators and advanced tokamaks and have aspect ratios similar to those of tokamaks (2-4). They are based on computed plasma configurations that are shaped in three dimensions to provide desired stability and transport properties. Experiments are planned as part of a program to develop this concept. A beta = 4% quasi-axisymmetric plasma configuration has been evaluated for the National Compact Stellarator Experiment (NCSX). It has amore » substantial bootstrap current and is shaped to stabilize ballooning, external kink, vertical, and neoclassical tearing modes without feedback or close-fitting conductors. Quasi-omnigeneous plasma configurations stable to ballooning modes at beta = 4% have been evaluated for the Quasi-Omnigeneous Stellarator (QOS) experiment. These equilibria have relatively low bootstrap currents and are insensitive to changes in beta. Coil configurations have been calculated that reconstruct these plasma configurations, preserving their important physics properties. Theory- and experiment-based confinement analyses are used to evaluate the technical capabilities needed to reach target plasma conditions. The physics basis for these complementary experiments is described.« less

Major Disruptions and Other Issues Driving the Design of the Ignitor Plasma Chamber

NASA Astrophysics Data System (ADS)

Ramogida, G.; Frosi, P.; Coppi, B.

2012-10-01

The Plasma Chamber of the Ignitor machine is designed according to the information available about electromagnetic loads coming from the experimental knowledge and the increasingly accurate numerical models of the eddy and halo currents resulting from the worst disruption events in existing machines. The developed models deal with static, dynamic and modal analysis. The loads during nominal operations and also those arising from plasma disruptions, by far the most important ones, have been taken into account, as well as the design problems arising from the Mo tiles in the inboard edge of the vacuum vessel, the Faraday shields covering the 6 ports devoted to the ICRH system and, finally, the reaction forces coming from the regions of constraints with the C-Clamps (the retaining structure that support the plasma chamber both statically and dynamically). The plasma chamber has to perform several additional functions, such as to keep the vacuum, be bakeable, and support the set of plates that carry the Mo tiles facing the plasma column. According to the present design the chamber is made of Inconel and has a thickness varying from 26 to 52 mm.

Spatially-Selective Membrane Permeabilization Induced by Cell-Solution Electrode Atmospheric Pressure Plasma Irradiation

NASA Astrophysics Data System (ADS)

Sasaki, Shota; Hokari, Yutaro; Kanzaki, Makoto; Kaneko, Toshiro

2015-09-01

Gene transfection, which is the process of deliberately introducing nucleic acids into cells, is expected to play an important role in medical treatment because the process is necessary for gene therapy and creation of induced pluripotent stem (iPS) cells. However, the conventional transfection methods have some problems, so we focus attention on promising transfection methods by atmospheric pressure plasma (APP). We have previously reported that the cell membrane permeability, which is closely related with gene transfection, is improved using a cell-solution electrode for generating He-APP. He-APP is irradiated to the solution containing the adherent cells and delivery materials such as fluorescent dyes (YOYO-1) and plasmid DNA (GFP). In case of YOYO-1 delivery, more than 80% of cells can be transferred only in the plasma-irradiated area and the spatially-selective membrane permeabilization is realized by the plasma irradiation. In addition, it is confirmed that plasmid DNA is transfected and the GFP genes are expressed using same APP irradiation system with no obvious cellular damage.

Integrated Blood Barcode Chips

PubMed Central

Fan, Rong; Vermesh, Ophir; Srivastava, Alok; Yen, Brian K.H.; Qin, Lidong; Ahmad, Habib; Kwong, Gabriel A.; Liu, Chao-Chao; Gould, Juliane; Hood, Leroy; Heath, James R.

2008-01-01

Blood comprises the largest version of the human proteome1. Changes of plasma protein profiles can reflect physiological or pathological conditions associated with many human diseases, making blood the most important fluid for clinical diagnostics2-4. Nevertheless, only a handful of plasma proteins are utilized in routine clinical tests. This is due to a host of reasons, including the intrinsic complexity of the plasma proteome1, the heterogeneity of human diseases and the fast kinetics associated with protein degradation in sampled blood5. Simple technologies that can sensitively sample large numbers of proteins over broad concentration ranges, from small amounts of blood, and within minutes of sample collection, would assist in solving these problems. Herein, we report on an integrated microfluidic system, called the Integrated Blood Barcode Chip (IBBC). It enables on-chip blood separation and the rapid measurement of a panel of plasma proteins from small quantities of blood samples including a fingerprick of whole blood. This platform holds potential for inexpensive, non-invasive, and informative clinical diagnoses, particularly, for point-of-care. PMID:19029914

Space plasma contractor research, 1988

NASA Technical Reports Server (NTRS)

Williams, John D.; Wilbur, Paul J.

1989-01-01

Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included.

Nitrogen oxides and methane treatment by non-thermal plasma

NASA Astrophysics Data System (ADS)

Alva, E.; Pacheco, M.; Colín, A.; Sánchez, V.; Pacheco, J.; Valdivia, R.; Soria, G.

2015-03-01

Non thermal plasma was used to treat nitrogen oxides (NOx) and methane (CH4), since they are important constituents of hydrocarbon combustion emissions processes and, both gases, play a key role in the formation of tropospheric ozone. These gases are involved in environmental problems like acid rain and some diseases such as bronchitis and pneumonia. In the case of methane is widely known its importance in the global climate change, and currently accounts for 30% of global warming. There is a growing concern for methane leaks, associated with a rapid expansion of unconventional oil and gas extraction techniques as well as a large-scale methane release from Arctic because of ice melting and the subsequent methane production of decaying organic matter. Therefore, methane mitigation is a key to avoid dangerous levels of global warming. The research, here reported, deals about the generation of non-thermal plasma with a double dielectric barrier (2DBD) at atmospheric pressure with alternating current (AC) for NOx and CH4 treatment. The degradation efficiencies and their respective power consumption for different reactor configurations (cylindrical and planar) are also reported. Qualitative and quantitative analysis of gases degradation are reported before and after treatment with cold plasma. Experimental and theoretical results are compared obtaining good removal efficiencies, superior to 90% and to 20% respectively for NOx and CH4.

Stopping and Coulomb explosion of energetic carbon clusters in a plasma irradiated by an intense laser field

NASA Astrophysics Data System (ADS)

Wang, Guiqiu; Wang, Younian

2015-09-01

The interaction of a charged particle beam with a plasma is a very important subject of relevance for many fields of physics, such as inertial confinement fusion (ICF) driven by ion or electron beams, high energy density physics, and related astrophysical problems. Recently, a promising ICF scheme has been proposed, in which the plasma target is irradiated simultaneously by intense laser and ion beams. For molecular ion or cluster, slowing down process will company the Coulomb explosion phenomenon. In this paper, we present a study of the effects of intense radiation field (RF) on the interaction of energetic carbon clusters in a plasma. The emphasis is laid on the dynamic polarization and correlation effects of the constituent ions within the cluster in order to disclose the role of the vicinage effects on the Coulomb explosion and energy deposition of the clusters in plasma. On the other hand, affecting of a strong laser field on the cluster propagating in plasma is considered, the influence of a large range of laser parameters and plasma parameters on the Coulomb explosion and stopping power are discussed. This work is supported by the National Natural Science Foundation of China (11375034), and the Fundamental Research Funds for the Central Universities of China (3132015144, 3132014337).

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Study of Globus-M Tokamak Poloidal System and Plasma Position Control

NASA Astrophysics Data System (ADS)

Dokuka, V. N.; Korenev, P. S.; Mitrishkin, Yu. V.; Pavlova, E. A.; Patrov, M. I.; Khayrutdinov, R. R.

2017-12-01

In order to provide efficient performance of tokamaks with vertically elongated plasma position, control systems for limited and diverted plasma configuration are required. The accuracy, stability, speed of response, and reliability of plasma position control as well as plasma shape and current control depend on the performance of the control system. Therefore, the problem of the development of such systems is an important and actual task in modern tokamaks. In this study, the measured signals from the magnetic loops and Rogowski coils are used to reconstruct the plasma equilibrium, for which linear models in small deviations are constructed. We apply methods of the H∞-optimization theory to the synthesize control system for vertical and horizontal position of plasma capable to working with structural uncertainty of the models of the plant. These systems are applied to the plasma-physical DINA code which is configured for the tokamak Globus-M plasma. The testing of the developed systems applied to the DINA code with Heaviside step functions have revealed the complex dynamics of plasma magnetic configurations. Being close to the bifurcation point in the parameter space of unstable plasma has made it possible to detect an abrupt change in the X-point position from the top to the bottom and vice versa. Development of the methods for reconstruction of plasma magnetic configurations and experience in designing plasma control systems with feedback for tokamaks provided an opportunity to synthesize new digital controllers for plasma vertical and horizontal position stabilization. It also allowed us to test the synthesized digital controllers in the closed loop of the control system with the DINA code as a nonlinear model of plasma.

Decreased Plasma Brain-Derived Neurotrophic Factor and Vascular Endothelial Growth Factor Concentrations during Military Training

PubMed Central

Nibuya, Masashi; Ishida, Toru; Yamamoto, Tetsuo; Mukai, Yasuo; Mitani, Keiji; Tsumatori, Gentaro; Scott, Daniel; Shimizu, Kunio

2014-01-01

Decreased concentrations of plasma brain-derived neurotrophic factor (BDNF) and serum BDNF have been proposed to be a state marker of depression and a biological indicator of loaded psychosocial stress. Stress evaluations of participants in military mission are critically important and appropriate objective biological parameters that evaluate stress are needed. In military circumstances, there are several problems to adopt plasma BDNF concentration as a stress biomarker. First, in addition to psychosocial stress, military missions inevitably involve physical exercise that increases plasma BDNF concentrations. Second, most participants in the mission do not have adequate quality or quantity of sleep, and sleep deprivation has also been reported to increase plasma BDNF concentration. We evaluated plasma BDNF concentrations in 52 participants on a 9-week military mission. The present study revealed that plasma BDNF concentration significantly decreased despite elevated serum enzymes that escaped from muscle and decreased quantity and quality of sleep, as detected by a wearable watch-type sensor. In addition, we observed a significant decrease in plasma vascular endothelial growth factor (VEGF) during the mission. VEGF is also neurotrophic and its expression in the brain has been reported to be up-regulated by antidepressive treatments and down-regulated by stress. This is the first report of decreased plasma VEGF concentrations by stress. We conclude that decreased plasma concentrations of neurotrophins can be candidates for mental stress indicators in actual stressful environments that include physical exercise and limited sleep. PMID:24586790

Weak stability of the plasma-vacuum interface problem

NASA Astrophysics Data System (ADS)

Catania, Davide; D'Abbicco, Marcello; Secchi, Paolo

2016-09-01

We consider the free boundary problem for the two-dimensional plasma-vacuum interface in ideal compressible magnetohydrodynamics (MHD). In the plasma region, the flow is governed by the usual compressible MHD equations, while in the vacuum region we consider the Maxwell system for the electric and the magnetic fields. At the free interface, driven by the plasma velocity, the total pressure is continuous and the magnetic field on both sides is tangent to the boundary. We study the linear stability of rectilinear plasma-vacuum interfaces by computing the Kreiss-Lopatinskiĭ determinant of an associated linearized boundary value problem. Apart from possible resonances, we obtain that the piecewise constant plasma-vacuum interfaces are always weakly linearly stable, independently of the size of tangential velocity, magnetic and electric fields on both sides of the characteristic discontinuity. We also prove that solutions to the linearized problem obey an energy estimate with a loss of regularity with respect to the source terms, both in the interior domain and on the boundary, due to the failure of the uniform Kreiss-Lopatinskiĭ condition, as the Kreiss-Lopatinskiĭ determinant associated with this linearized boundary value problem has roots on the boundary of the frequency space. In the proof of the a priori estimates, a crucial part is played by the construction of symmetrizers for a reduced differential system, which has poles at which the Kreiss-Lopatinskiĭ condition may fail simultaneously.

Well-posedness of the plasma-vacuum interface problem

NASA Astrophysics Data System (ADS)

Secchi, Paolo; Trakhinin, Yuri

2014-01-01

We consider the free-boundary problem for the plasma-vacuum interface in ideal compressible magnetohydrodynamics (MHD). In the plasma region the flow is governed by the usual compressible MHD equations, while in the vacuum region we consider the pre-Maxwell dynamics for the magnetic field. At the free interface, driven by the plasma velocity, the total pressure is continuous and the magnetic field on both sides is tangent to the boundary. The plasma-vacuum system is not isolated from the outside world, because of a given surface current on the fixed boundary that forces oscillations. Under a suitable stability condition satisfied at each point of the initial interface, stating that the magnetic fields on either side of the interface are not collinear, we show the existence and uniqueness of the solution to the nonlinear plasma-vacuum interface problem in suitable anisotropic Sobolev spaces. The proof is based on the results proved in the companion paper (Secchi and Trakhinin 2013 Interfaces Free Boundaries 15 323-57), about the well-posedness of the homogeneous linearized problem and the proof of a basic a priori energy estimate. The proof of the resolution of the nonlinear problem given in the present paper follows from the analysis of the elliptic system for the vacuum magnetic field, a suitable tame estimate in Sobolev spaces for the full linearized equations, and a Nash-Moser iteration.

Extension of the SIESTA MHD equilibrium code to free-plasma-boundary problems

DOE PAGES

Peraza-Rodriguez, Hugo; Reynolds-Barredo, J. M.; Sanchez, Raul; ...

2017-08-28

Here, SIESTA is a recently developed MHD equilibrium code designed to perform fast and accurate calculations of ideal MHD equilibria for three-dimensional magnetic configurations. Since SIESTA does not assume closed magnetic surfaces, the solution can exhibit magnetic islands and stochastic regions. In its original implementation SIESTA addressed only fixed-boundary problems. That is, the shape of the plasma edge, assumed to be a magnetic surface, was kept fixed as the solution iteratively converges to equilibrium. This condition somewhat restricts the possible applications of SIESTA. In this paper we discuss an extension that will enable SIESTA to address free-plasma-boundary problems, opening upmore » the possibility of investigating problems in which the plasma boundary is perturbed either externally or internally. As an illustration, SIESTA is applied to a configuration of the W7-X stellarator.« less

Extension of the SIESTA MHD equilibrium code to free-plasma-boundary problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peraza-Rodriguez, Hugo; Reynolds-Barredo, J. M.; Sanchez, Raul

Here, SIESTA is a recently developed MHD equilibrium code designed to perform fast and accurate calculations of ideal MHD equilibria for three-dimensional magnetic configurations. Since SIESTA does not assume closed magnetic surfaces, the solution can exhibit magnetic islands and stochastic regions. In its original implementation SIESTA addressed only fixed-boundary problems. That is, the shape of the plasma edge, assumed to be a magnetic surface, was kept fixed as the solution iteratively converges to equilibrium. This condition somewhat restricts the possible applications of SIESTA. In this paper we discuss an extension that will enable SIESTA to address free-plasma-boundary problems, opening upmore » the possibility of investigating problems in which the plasma boundary is perturbed either externally or internally. As an illustration, SIESTA is applied to a configuration of the W7-X stellarator.« less

The effect of parity on maternal body mass index, plasma mineral element status and new-born anthropometrics.

PubMed

Ugwuja, Emmanuel I; Nnabu, Richard C; Ezeonu, Paul O; Uro-Chukwu, Henry

2015-09-01

Adverse pregnancy outcome is an important public health problem that has been partly associated with increasing maternal parity. To determine the effect of parity on maternal body mass index (BMI), mineral element status and newborn anthropometrics. Data for 349 pregnant women previously studied for the impacts of maternal plasma mineral element status on pregnancy and its outcomes was analysed. Obstetric and demographic data and 5mls of blood samples were obtained from each subject. Blood lead, plasma copper, iron and zinc were determined using atomic absorption spectrophotometer. Maternal BMI increases with parity. Women with parity two had significantly higher plasma zinc but lower plasma copper with comparable levels of the elements in nulliparous and higher parity groups. Although plasma iron was comparable among the groups, blood lead was significantly higher in parity > three. Newborn birth length increases with parity with a positive correlation between parity and maternal BMI (r = 0.221; p = 0.001) and newborn birth length (r = 0.170; p = 0.002) while plasma copper was negatively correlated with newborn's head circumference (r = -0.115; p = 0.040). It is plausible that parity affects maternal BMI and newborn anthropometrics through alterations in maternal plasma mineral element levels. While further studies are desired to confirm the present findings, there is need for pregnant and would-be pregnant women to diversify their diet to optimize their mineral element status.

Eulerian simulations of collisional effects on electrostatic plasma waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzi, Oreste; Valentini, Francesco; Perrone, Denise

2013-09-15

The problem of collisions in a plasma is a wide subject with a huge historical literature. In fact, the description of realistic plasmas is a tough problem to attack, both from the theoretical and the numerical point of view. In this paper, a Eulerian time-splitting algorithm for the study of the propagation of electrostatic waves in collisional plasmas is presented. Collisions are modeled through one-dimensional operators of the Fokker-Planck type, both in linear and nonlinear forms. The accuracy of the numerical code is discussed by comparing the numerical results to the analytical predictions obtained in some limit cases when tryingmore » to evaluate the effects of collisions in the phenomenon of wave plasma echo and collisional dissipation of Bernstein-Greene-Kruskal waves. Particular attention is devoted to the study of the nonlinear Dougherty collisional operator, recently used to describe the collisional dissipation of electron plasma waves in a pure electron plasma column [M. W. Anderson and T. M. O'Neil, Phys. Plasmas 14, 112110 (2007)]. Finally, for the study of collisional plasmas, a recipe to set the simulation parameters in order to prevent the filamentation problem can be provided, by exploiting the property of velocity diffusion operators to smooth out small velocity scales.« less

Global problems in magnetospheric plasma physics and prospects for their solution

NASA Technical Reports Server (NTRS)

Roederer, J. G.

1977-01-01

Selected problems in magnetospheric plasma physics are critically reviewed. The discussion is restricted to questions that are 'global' in nature (i.e., involve the magnetosphere as a whole) and that are beyond the stage of systematic survey or isolated study requirements. Only low-energy particle aspects are discussed. The article focuses on the following subjects: (1) the effect of the interplanetary magnetic field on the topography, topology, and stability of the magnetospheric boundary; (2) solar-wind plasma entry into the magnetosphere; (3) plasma storage and release mechanisms in the magnetospheric tail; and (4) magnetic-field-aligned currents and magnetosphere-ionosphere interactions. A brief discussion of the prospects for the solution of these problems during and after the International Magnetospheric Study is given.

Performance of an ion-cyclotron-wave plasma apparatus operated in the radiofrequency sustained mode

NASA Technical Reports Server (NTRS)

Swett, C. C.; Woollett, R. R.

1973-01-01

An experimental study has been made of an ion-cyclotron-wave apparatus operated in the RF-sustained mode, that is, a mode in which the Stix RF coil both propagates the waves and maintains the plasma. Problems associated with this method of operation are presented. Some factors that are important to the coupling of RF power are noted. In general, the wave propagation and wave damping data agree with theory. Some irregularities in wave fields are observed. Maximum ion temperature is 870 eV at a density of five times 10 to the 12th power cu cm and RF power of 90 kW. Coupling efficiency is 70 percent.

Operating features of an ion-cyclotron-wave plasma apparatus running in the RF-sustained mode

NASA Technical Reports Server (NTRS)

Swett, C. C.

1972-01-01

An experimental study has been made of an ion-cyclotron-wave apparatus operated in the RF-sustained mode. This is a mode in which the Stix RF coil both propagates the waves and maintains the plasma. Problems associated with this method of operation are presented. Some factors that are important to the coupling of RF power are noted. In general, the wave-propagation and wave-damping data agree with theory. Some irregularities in wave fields are observed. Maximum ion temperature is 870 eV at a density of 5 times 10 to the 12th power per cubic centimeter and RF power of 90 kW. Coupling efficiency is 70 percent.

Electrostatic twisted modes in multi-component dusty plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayub, M. K.; National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000; Pohang University of Sciences and Technology, Pohang, Gyeongbuk 790-784

Various electrostatic twisted modes are re-investigated with finite orbital angular momentum in an unmagnetized collisionless multi-component dusty plasma, consisting of positive/negative charged dust particles, ions, and electrons. For this purpose, hydrodynamical equations are employed to obtain paraxial equations in terms of density perturbations, while assuming the Gaussian and Laguerre-Gaussian (LG) beam solutions. Specifically, approximated solutions for potential problem are studied by using the paraxial approximation and expressed the electric field components in terms of LG functions. The energy fluxes associated with these modes are computed and corresponding expressions for orbital angular momenta are derived. Numerical analyses reveal that radial/angular modemore » numbers as well as dust number density and dust charging states strongly modify the LG potential profiles attributed to different electrostatic modes. Our results are important for understanding particle transport and energy transfer due to wave excitations in multi-component dusty plasmas.« less

A computer model of solar panel-plasma interactions

NASA Technical Reports Server (NTRS)

Cooke, D. L.; Freeman, J. W.

1980-01-01

High power solar arrays for satellite power systems are presently being planned with dimensions of kilometers, and with tens of kilovolts distributed over their surface. Such systems face many plasma interaction problems, such as power leakage to the plasma, particle focusing, and anomalous arcing. These effects cannot be adequately modeled without detailed knowledge of the plasma sheath structure and space charge effects. Laboratory studies of 1 by 10 meter solar array in a simulated low Earth orbit plasma are discussed. The plasma screening process is discussed, program theory is outlined, and a series of calibration models is presented. These models are designed to demonstrate that PANEL is capable of accurate self consistant space charge calculations. Such models include PANEL predictions for the Child-Langmuir diode problem.

Plasma drag on a dust grain due to Coulomb collisions

NASA Technical Reports Server (NTRS)

Northrop, T. G.; Birmingham, T. J.

1990-01-01

Expressions are given for the drag due to Coulomb collisions on a charged dust grain moving through a plasma. The commonly used Chandrasekhar (1943) result does not include large scattering angles or plasma collective effects. An equation given by Morfill et al. (1980) which does include large scattering angles, is limited to one-dimensional plasma particle motion and can give at least an order of magnitude too much drag. This paper also makes use of an analogy between the drag problem and problems in electrostatics. This analogy permits generalization to any isotropic plasma of an observation made by Chandrasekhar for a Maxwellian, namely, that the drag is independent of the presence or absence of plasma particles moving faster than the grain. Finally, the contribution of plasma collective effects to the drag is studied with the inclusion of large scattering angles.

Improvement of Thrust Characteristics of Helicon Plasma Thruster using Local Gas Fueling Method

NASA Astrophysics Data System (ADS)

Kuwahara, Daisuke; Amma, Kosuke; Ishigami, Yuichi; Igarashi, Akihiko; Nishimoto, Shinichi; Shinohara, Shunjiro; Miyazawa, Junichi

2017-10-01

A helicon plasma thruster is proposed as a long-lifetime electric thruster which has non-direct contact electrodes. Here, a neutral particle, e.g., H2, Ar, and Xe works, as a fuel gas. In most cases, these gases are supplied into a discharge tube by the use of a simple nozzle. Therefore, the neutral particle fills a discharge tube homogenous. However, there are two problems in this configuration. First, there is a limitation of an electron density increase, due to a neutral particle depletion in the central region of the high-density helicon plasma. This limitation reduces the thrust performance directly. Second, the high-density plasma causes an erosion of an inner discharge tube wall. For the future MW class thruster, this problem will become serious because the particle and heat fluxes of the plasma will increase drastically. To solve above-mentioned problems, we have proposed local fueling methods for the high-density helicon plasma. In this presentation, we will show the methods and experimental results using a fueling tube, inserted in a plasma directly. This work is supported by JSPS KAKENHI Grant Number 16K17843 and NIFS Collaboration Research program (NIFSKBAF016).

A model of early formation of uranium molecular oxides in laser-ablated plasmas

NASA Astrophysics Data System (ADS)

Finko, Mikhail; Curreli, Davide; Azer, Magdi; Weisz, David; Crowhurst, Jonathan; Rose, Timothy; Koroglu, Batikan; Radousky, Harry; Zaug, Joseph; Armstrong, Mike

2017-10-01

An important problem within the field of nuclear forensics is fractionation: the formation of post-detonation nuclear debris whose composition does not reflect that of the source weapon. We are investigating uranium fractionation in rapidly cooling plasma using a combined experimental and modeling approach. In particular, we use laser ablation of uranium metal samples to produce a low-temperature plasma with physical conditions similar to a condensing nuclear fireball. Here we present a first plasma-chemistry model of uranium molecular species formation during the early stage of laser ablated plasma evolution in atmospheric oxygen. The system is simulated using a global kinetic model with rate coefficients calculated according to literature data and the application of reaction rate theory. The model allows for a detailed analysis of the evolution of key uranium molecular species and represents the first step in producing a uranium fireball model that is kinetically validated against spatially and temporally resolved spectroscopy measurements. This project was sponsored by the DoD, Defense Threat Reduction Agency, Grant HDTRA1-16- 1-0020. This work was performed in part under the auspices of the U.S. DoE by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344.

Investigation of a Light Gas Helicon Plasma Source for the VASIMR Space Propulsion System

NASA Technical Reports Server (NTRS)

Squire, J. P.; Chang-Diaz, F. R.; Jacobson, V. T.; Glover, T. W.; Baity, F. W.; Carter, M. D.; Goulding, R. H.; Bengtson, R. D.; Bering, E. A., III

2003-01-01

An efficient plasma source producing a high-density (approx.10(exp 19/cu m) light gas (e.g. H, D, or He) flowing plasma with a high degree of ionization is a critical component of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept. We are developing an antenna to apply ICRF power near the fundamental ion cyclotron resonance to further accelerate the plasma ions to velocities appropriate for space propulsion applications. The high degree of ionization and a low vacuum background pressure are important to eliminate the problem of radial losses due to charge exchange. We have performed parametric (e.g. gas flow, power (0.5 - 3 kW), magnetic field , frequency (25 and 50 MHz)) studies of a helicon operating with gas (H2 D2, He, N2 and Ar) injected at one end with a high magnetic mirror downstream of the antenna. We have explored operation with a cusp and a mirror field upstream. Plasma flows into a low background vacuum (<10(exp -4) torr) at velocities higher than the ion sound speed. High densities (approx. 10(exp 19/cu m) have been achieved at the location where ICRF will be applied, just downstream of the magnetic mirror.

Particle Production in Strong Electromagnetic Fields in Relativistic Heavy-Ion Collisions

DOE PAGES

Tuchin, Kirill

2013-01-01

I reviewmore » the origin and properties of electromagnetic fields produced in heavy-ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~ m π 2 at RHIC and ~ 10 m π 2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma lives as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane, and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J / ψ dissociation via Lorentz ionization mechanism, and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.« less

Quantum stream instability in coupled two-dimensional plasmas

NASA Astrophysics Data System (ADS)

Akbari-Moghanjoughi, M.

2014-08-01

In this paper the quantum counter-streaming instability problem is studied in planar two-dimensional (2D) quantum plasmas using the coupled quantum hydrodynamic (CQHD) model which incorporates the most important quantum features such as the statistical Fermi-Dirac electron pressure, the electron-exchange potential and the quantum diffraction effect. The instability is investigated for different 2D quantum electron systems using the dynamics of Coulomb-coupled carriers on each plasma sheet when these plasmas are both monolayer doped graphene or metalfilm (corresponding to 2D Dirac or Fermi electron fluids). It is revealed that there are fundamental differences between these two cases regarding the effects of Bohm's quantum potential and the electron-exchange on the instability criteria. These differences mark yet another interesting feature of the effect of the energy band dispersion of Dirac electrons in graphene. Moreover, the effects of plasma number-density and coupling parameter on the instability criteria are shown to be significant. This study is most relevant to low dimensional graphene-based field-effect-transistor (FET) devices. The current study helps in understanding the collective interactions of the low-dimensional coupled ballistic conductors and the nanofabrication of future graphene-based integrated circuits.

The island coalescence problem: Scaling of reconnection in extended fluid models including higher-order moments

DOE PAGES

Ng, Jonathan; Huang, Yi -Min; Hakim, Ammar; ...

2015-11-05

As modeling of collisionless magnetic reconnection in most space plasmas with realistic parameters is beyond the capability of today's simulations, due to the separation between global and kinetic length scales, it is important to establish scaling relations in model problems so as to extrapolate to realistic scales. Furthermore, large scale particle-in-cell simulations of island coalescence have shown that the time averaged reconnection rate decreases with system size, while fluid systems at such large scales in the Hall regime have not been studied. Here, we perform the complementary resistive magnetohydrodynamic (MHD), Hall MHD, and two fluid simulations using a ten-moment modelmore » with the same geometry. In contrast to the standard Harris sheet reconnection problem, Hall MHD is insufficient to capture the physics of the reconnection region. Additionally, motivated by the results of a recent set of hybrid simulations which show the importance of ion kinetics in this geometry, we evaluate the efficacy of the ten-moment model in reproducing such results.« less

Information hidden in the velocity distribution of ions and the exact kinetic Bohm criterion

NASA Astrophysics Data System (ADS)

Tsankov, Tsanko V.; Czarnetzki, Uwe

2017-05-01

Non-equilibrium distribution functions of electrons and ions play an important role in plasma physics. A prominent example is the kinetic Bohm criterion. Since its first introduction it has been controversial for theoretical reasons and due to the lack of experimental data, in particular on the ion distribution function. Here we resolve the theoretical as well as the experimental difficulties by an exact solution of the kinetic Boltzmann equation including charge exchange collisions and ionization. This also allows for the first time non-invasive measurement of spatially resolved ion velocity distributions, absolute values of the ion and electron densities, temperatures, and mean energies as well as the electric field and the plasma potential in the entire plasma. The non-invasive access to the spatially resolved distribution functions of electrons and ions is applied to the problem of the kinetic Bohm criterion. Theoretically a so far missing term in the criterion is derived and shown to be of key importance. With the new term the validity of the kinetic criterion at high collisionality and its agreement with the fluid picture are restored. All findings are supported by experimental data, theory and a numerical model with excellent agreement throughout.

Overview of plasma technology used in medicine

NASA Astrophysics Data System (ADS)

Ryan, Thomas P.; Stalder, Kenneth R.; Woloszko, Jean

2013-02-01

Plasma Medicine is a growing field that is having an impact in several important areas in therapeutic patient care, combining plasma physics, biology, and clinical medicine. Historically, plasmas in medicine were used in electrosurgery for cautery and non-contact hemostasis. Presently, non-thermal plasmas have attained widespread use in medicine due to their effectiveness and compatibility with biological systems. The paper will give a general overview of how low temperature, non-equilibrium, gas plasmas operate, both from physics and biology perspectives. Plasma is commonly described as the fourth state of matter and is typically comprised of charged species, active molecules and atoms, as well as a source of UV and photons. The most active areas of plasma technology applications are in wound treatment; tissue regeneration; inactivation of pathogens, including biofilms; treating skin diseases; and sterilization. There are several means of generating plasmas for use in medical applications, including plasma jets, dielectric barrier discharges, capacitively or inductively coupled discharges, or microplasmas. These systems overcome the former constraints of high vacuum, high power requirements and bulky systems, into systems that use room air and other gases and liquids at low temperature, low power, and hand-held operation at atmospheric pressure. Systems will be discussed using a variety of energy sources: pulsed DC, AC, microwave and radiofrequency, as well as the range of frequency, pulse duration, and gas combinations in an air environment. The ionic clouds and reactive species will be covered in terms of effects on biological systems. Lastly, several commercial products will be overviewed in light of the technology utilized, health care problems being solved, and clinical trial results.

Electron density measurements for plasma adaptive optics

NASA Astrophysics Data System (ADS)

Neiswander, Brian W.

Over the past 40 years, there has been growing interest in both laser communications and directed energy weapons that operate from moving aircraft. As a laser beam propagates from an aircraft in flight, it passes through boundary layers, turbulence, and shear layers in the near-region of the aircraft. These fluid instabilities cause strong density gradients which adversely affect the transmission of laser energy to a target. Adaptive optics provides corrective measures for this problem but current technology cannot respond quickly enough to be useful for high speed flight conditions. This research investigated the use of plasma as a medium for adaptive optics for aero-optics applications. When a laser beam passes through plasma, its phase is shifted proportionally to the electron density and gas heating within the plasma. As a result, plasma can be utilized as a dynamically controllable optical medium. Experiments were carried out using a cylindrical dielectric barrier discharge plasma chamber which generated a sub-atmospheric pressure, low-temperature plasma. An electrostatic model of this design was developed and revealed an important design constraint relating to the geometry of the chamber. Optical diagnostic techniques were used to characterize the plasma discharge. Single-wavelength interferometric experiments were performed and demonstrated up to 1.5 microns of optical path difference (OPD) in a 633 nm laser beam. Dual-wavelength interferometry was used to obtain time-resolved profiles of the plasma electron density and gas heating inside the plasma chamber. Furthermore, a new multi-wavelength infrared diagnostic technique was developed and proof-of-concept simulations were conducted to demonstrate the system's capabilities.

BOOK REVIEW: Fundamentals of Plasma Physics

NASA Astrophysics Data System (ADS)

Cargill, P. J.

2007-02-01

The widespread importance of plasmas in many areas of contemporary physics makes good textbooks in the field that are both introductory and comprehensive invaluable. This new book by Paul Bellen from CalTech by and large meets these goals. It covers the traditional textbook topics such as particle orbits, the derivation of the MHD equations from Vlasov theory, cold and warm plasma waves, Landau damping, as well as in the later chapters less common subjects such as magnetic helicity, nonlinear processes and dusty plasmas. The book is clearly written, neatly presented, and each chapter has a number of exercises or problems at their end. The author has also thankfully steered clear of the pitfall of filling the book with his own research results. The preface notes that the book is designed to provide an introduction to plasma physics for final year undergraduate and post-graduate students. However, it is difficult to see many physics undergraduates now at UK universities getting to grips with much of the content since their mathematics is not of a high enough standard. Students in Applied Mathematics departments would certainly fare better. An additional problem for the beginner is that some of the chapters do not lead the reader gently into a subject, but begin with quite advanced concepts. Being a multi-disciplinary subject, beginners tend to find plasma physics quite hard enough even when done simply. For postgraduate students these criticisms fade away and this book provides an excellent introduction. More senior researchers should also enjoy the book, especially Chapters 11-17 where more advanced topics are discussed. I found myself continually comparing the book with my favourite text for many years, `The Physics of Plasmas' by T J M Boyd and J J Sanderson, reissued by Cambridge University Press in 2003. Researchers would want both books on their shelves, both for the different ways basic plasma physics is covered, and the diversity of more advanced topics. For the undergraduate level, I would find it easier to construct an introductory course from Boyd and Sanderson.

Systemic study on the safety of immuno-deficient nude mice treated by atmospheric plasma-activated water

NASA Astrophysics Data System (ADS)

Dehui, XU; Qingjie, CUI; Yujing, XU; Bingchuan, WANG; Miao, TIAN; Qiaosong, LI; Zhijie, LIU; Dingxin, LIU; Hailan, CHEN; Michael, G. KONG

2018-04-01

Cold atmospheric-pressure plasma is a new technology, widely used in many fields of biomedicine, especially in cancer treatment. Cold plasma can selectively kill a variety of tumor cells, and its biological safety in clinical trials is also very important. In many cases, the patient’s immune level is relatively low, so we first studied the safety assessment of plasma treatment in an immuno-compromised animal model. In this study, we examined the safety of immuno-deficient nude mice by oral lavage treatment of plasma-activated water, and studied the growth status, main organs and blood biochemical indexes. Acute toxicity test results showed that the maximum dose of plasma treatment for 15 min had no lethal effect and other acute toxicity. There were no significant changes in body weight and survival status of mice after 2 min and 4 min of plasma-activated water (PAW) treatment for 2 weeks. After treatment, the major organs, including heart, liver, spleen, lung and kidney, were not significantly changed in organ coefficient and tissue structure. Blood biochemical markers showed that blood neutrophils and mononuclear cells were slightly increased, and the others remained unchanged. Liver function, renal function, electrolytes, glucose metabolism and lipid metabolism were not affected by different doses of PAW treatment. The above results indicate that PAW treatment can be used to treat immuno-deficient nude mice without significant safety problems.

Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas

NASA Astrophysics Data System (ADS)

Ross, A. E.; McKenzie, D. R.

2016-04-01

Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present.

An evaluation method of the profile of plasma-induced defects based on capacitance-voltage measurement

NASA Astrophysics Data System (ADS)

Okada, Yukimasa; Ono, Kouichi; Eriguchi, Koji

2017-06-01

Aggressive shrinkage and geometrical transition to three-dimensional structures in metal-oxide-semiconductor field-effect transistors (MOSFETs) lead to potentially serious problems regarding plasma processing such as plasma-induced physical damage (PPD). For the precise control of material processing and future device designs, it is extremely important to clarify the depth and energy profiles of PPD. Conventional methods to estimate the PPD profile (e.g., wet etching) are time-consuming. In this study, we propose an advanced method using a simple capacitance-voltage (C-V) measurement. The method first assumes the depth and energy profiles of defects in Si substrates, and then optimizes the C-V curves. We applied this methodology to evaluate the defect generation in (100), (111), and (110) Si substrates. No orientation dependence was found regarding the surface-oxide layers, whereas a large number of defects was assigned in the case of (110). The damaged layer thickness and areal density were estimated. This method provides the highly sensitive PPD prediction indispensable for designing future low-damage plasma processes.

Simulations of dusty plasmas using a special-purpose computer system designed for gravitational N-body problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, K.; Mizuno, Y.; Hibino, S.

2006-01-15

Simulations of dusty plasmas were performed using GRAPE-6, a special-purpose computer designed for gravitational N-body problems. The collective behavior of dust particles, which are injected into the plasma, was studied by means of three-dimensional computer simulations. As an example of a dusty plasma simulation, experiments on Coulomb crystals in plasmas are simulated. Formation of a quasi-two-dimensional Coulomb crystal has been observed under typical laboratory conditions. Another example was to simulate movement of dust particles in plasmas under microgravity conditions. Fully three-dimensional spherical structures of dust clouds have been observed. For the simulation of a dusty plasma in microgravity with 3x10{supmore » 4} particles, GRAPE-6 can perform the whole operation 1000 times faster than by using a Pentium 4 1.6 GHz processor.« less

Plasma Modeling with Speed-Limited Particle-in-Cell Techniques

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Werner, G. R.; Cary, J. R.; Stoltz, P. H.

2017-10-01

Speed-limited particle-in-cell (SLPIC) modeling is a new particle simulation technique for modeling systems wherein numerical constraints, e.g. limitations on timestep size required for numerical stability, are significantly more restrictive than is needed to model slower kinetic processes of interest. SLPIC imposes artificial speed-limiting behavior on fast particles whose kinetics do not play meaningful roles in the system dynamics, thus enabling larger simulation timesteps and more rapid modeling of such plasma discharges. The use of SLPIC methods to model plasma sheath formation and the free expansion of plasma into vacuum will be demonstrated. Wallclock times for these simulations, relative to conventional PIC, are reduced by a factor of 2.5 for the plasma expansion problem and by over 6 for the sheath formation problem; additional speedup is likely possible. Physical quantities of interest are shown to be correct for these benchmark problems. Additional SLPIC applications will also be discussed. Supported by US DoE SBIR Phase I/II Award DE-SC0015762.

Observational Signatures of Coronal Heating Mechanisms

NASA Astrophysics Data System (ADS)

Judge, Philip

1998-11-01

Many mechanisms for heating the corona have been proposed since the problem was identified by Edlen more than 50 years ago. Identifying those that are important is a challenging problem that has so far not been resolved. One thing is clear: based upon a variety of observations, the corona is heated by conversion of magnetic flux into thermal energy. The flux emerges from sub-photospheric layers and is buffeted by photospheric dynamics. The ``coronal heating problem'' is to identify how, given the high conductivities of coronal plasma, the magnetic energy is dissipated. After reviewing some basic observational facts and placing the corona into appropriate physical regimes, I will focus on two pieces of information recently obtained from spacecraft. In one, I will discuss the interpretation of line profiles from the UVCS instrument on the SOHO spacecraft, presented by Kohl and colleagues. These observations indicate the presence of asymmetric particle distribution functions low in the solar wind, so I will discuss implications for heating mechanisms for plasma on these ``open'' field lines, in terms of ion cyclotron resonant heating by high frequency Alfven waves. In the other, I will try to review evidence for the ``nano-flare'' heating mechanism proposed by Parker to explain the heating of plasma along closed field lines, such as are present in active regions, based upon data from the SOHO and TRACE spacecraft. Parker's picture is one of slow field line ``braiding'', driven by random footpoint motions, with sudden energy release at critical energies. An attempt will be made to relate these different mechanisms by looking for the source of the high frequency waves implied by the UVCS observations.

Toward the automated analysis of plasma physics problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mynick, H.E.

1989-04-01

A program (CALC) is described, which carries out nontrivial plasma physics calculations, in a manner intended to emulate the approach of a human theorist. This includes the initial process of gathering the relevant equations from a plasma knowledge base, and then determining how to solve them. Solution of the sets of equations governing physics problems, which in general have a nonuniform,irregular structure, not amenable to solution by standardized algorithmic procedures, is facilitated by an analysis of the structure of the equations and the relations among them. This often permits decompositions of the full problem into subproblems, and other simplifications inmore » form, which renders the resultant subsystems soluble by more standardized tools. CALC's operation is illustrated by a detailed description of its treatment of a sample plasma calculation. 5 refs., 3 figs.« less

Hermite Polynomials and the Inverse Problem for Collisionless Equilibria

NASA Astrophysics Data System (ADS)

Allanson, O.; Neukirch, T.; Troscheit, S.; Wilson, F.

2017-12-01

It is long established that Hermite polynomial expansions in either velocity or momentum space can elegantly encode the non-Maxwellian velocity-space structure of a collisionless plasma distribution function (DF). In particular, Hermite polynomials in the canonical momenta naturally arise in the consideration of the 'inverse problem in collisionless equilibria' (IPCE): "for a given macroscopic/fluid equilibrium, what are the self-consistent Vlasov-Maxwell equilibrium DFs?". This question is of particular interest for the equilibrium and stability properties of a given macroscopic configuration, e.g. a current sheet. It can be relatively straightforward to construct a formal solution to IPCE by a Hermite expansion method, but several important questions remain regarding the use of this method. We present recent work that considers the necessary conditions of non-negativity, convergence, and the existence of all moments of an equilibrium DF solution found for IPCE. We also establish meaningful analogies between the equations that link the microscopic and macrosopic descriptions of the Vlasov-Maxwell equilibrium, and those that solve the initial value problem for the heat equation. In the language of the heat equation, IPCE poses the pressure tensor as the 'present' heat distribution over an infinite domain, and the non-Maxwellian features of the DF as the 'past' distribution. We find sufficient conditions for the convergence of the Hermite series representation of the DF, and prove that the non-negativity of the DF can be dependent on the magnetisation of the plasma. For DFs that decay at least as quickly as exp(-v^2/4), we show non-negativity is guaranteed for at least a finite range of magnetisation values, as parameterised by the ratio of the Larmor radius to the gradient length scale. 1. O. Allanson, T. Neukirch, S. Troscheit & F. Wilson: From one-dimensional fields to Vlasov equilibria: theory and application of Hermite polynomials, Journal of Plasma Physics, 82, 905820306, 2016 2. O. Allanson, S. Troscheit & T. Neukirch: The inverse problem for collisionless plasma equilibria (invited paper for IMA Journal of Applied Mathematics, under review)

Gridless particle technique for the Vlasov-Poisson system in problems with high degree of symmetry

NASA Astrophysics Data System (ADS)

Boella, E.; Coppa, G.; D'Angola, A.; Peiretti Paradisi, B.

2018-03-01

In the paper, gridless particle techniques are presented in order to solve problems involving electrostatic, collisionless plasmas. The method makes use of computational particles having the shape of spherical shells or of rings, and can be used to study cases in which the plasma has spherical or axial symmetry, respectively. As a computational grid is absent, the technique is particularly suitable when the plasma occupies a rapidly changing space region.

PANDORA, a new facility for interdisciplinary in-plasma physics

NASA Astrophysics Data System (ADS)

Mascali, D.; Musumarra, A.; Leone, F.; Romano, F. P.; Galatà, A.; Gammino, S.; Massimi, C.

2017-07-01

PANDORA, Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archaeometry, is planned as a new facility based on a state-of-the-art plasma trap confining energetic plasma for performing interdisciplinary research in the fields of Nuclear Astrophysics, Astrophysics, Plasma Physics and Applications in Material Science and Archaeometry: the plasmas become the environment for measuring, for the first time, nuclear decay rates in stellar-like condition (such as 7Be decay and beta-decay involved in s-process nucleosynthesis), especially as a function of the ionization state of the plasma ions. These studies will give important contributions for addressing several astrophysical issues in both stellar and primordial nucleosynthesis environment ( e.g., determination of solar neutrino flux and 7Li Cosmological Problem), moreover the confined energetic plasma will be a unique light source for high-performance stellar spectroscopy measurements in the visible, UV and X-ray domains, offering advancements in observational astronomy. As to magnetic fields, the experimental validation of theoretical first- and second-order Landé factors will drive the layout of next-generation polarimetric units for the high-resolution spectrograph of the future giant telescopes. In PANDORA new plasma heating methods will be explored, that will push forward the ion beam output, in terms of extracted intensity and charge states. More, advanced and optimized injection methods of ions in an ECR plasma will be experimented, with the aim to optimize its capture efficiency. This will be applied to the ECR-based Charge Breeding technique, that will improve the performances of the SPES ISOL-facility at Laboratori Nazionali di Legnaro-INFN. Finally, PANDORA will be suitable for energy conversion, making the plasma a source of high-intensity electromagnetic radiation, for applications in material science and archaeometry.

Improved Simulations of Astrophysical Plasmas: Computation of New Atomic Data

NASA Technical Reports Server (NTRS)

Gorczyca, Thomas W.; Korista, Kirk T.

2005-01-01

Our research program is designed to carry out state-of-the-art atomic physics calculations crucial to advancing our understanding of fundamental astrophysical problems. We redress the present inadequacies in the atomic data base along two important areas: dielectronic recombination and inner-shell photoionization and multiple electron ejection/Auger fluorescence therefrom. All of these data are disseminated to the astrophysical community in the proper format for implementation in spectral simulation code.

Numerical methods for large-scale, time-dependent partial differential equations

NASA Technical Reports Server (NTRS)

Turkel, E.

1979-01-01

A survey of numerical methods for time dependent partial differential equations is presented. The emphasis is on practical applications to large scale problems. A discussion of new developments in high order methods and moving grids is given. The importance of boundary conditions is stressed for both internal and external flows. A description of implicit methods is presented including generalizations to multidimensions. Shocks, aerodynamics, meteorology, plasma physics and combustion applications are also briefly described.

Fundamental Mechanisms, Predictive Modeling, and Novel Aerospace Applications of Plasma Assisted Combustion. Overview of OSU Research Plan

DTIC Science & Technology

2009-11-04

air, low-temperature plasma chemistry kinetic model Nonequilibrium Thermodynamics Laboratories The Ohio State University • Air plasma model...problems require separate analysis: • Nsec pulse plasma / sheath models cannot incorporate detailed reactive plasma chemistry : too many species ( 100...and reactions ( 1 000)~ ~ , • Detailed plasma chemistry models (quasi-neutral) cannot incorporate repetitive, nsec time scale sheath dynamics and plasma

Quantum states and optical responses of low-dimensional electron hole systems

NASA Astrophysics Data System (ADS)

Ogawa, Tetsuo

2004-09-01

Quantum states and their optical responses of low-dimensional electron-hole systems in photoexcited semiconductors and/or metals are reviewed from a theoretical viewpoint, stressing the electron-hole Coulomb interaction, the excitonic effects, the Fermi-surface effects and the dimensionality. Recent progress of theoretical studies is stressed and important problems to be solved are introduced. We cover not only single-exciton problems but also few-exciton and many-exciton problems, including electron-hole plasma situations. Dimensionality of the Wannier exciton is clarified in terms of its linear and nonlinear responses. We also discuss a biexciton system, exciton bosonization technique, high-density degenerate electron-hole systems, gas-liquid phase separation in an excited state and the Fermi-edge singularity due to a Mahan exciton in a low-dimensional metal.

Magnetic reconnection in terms of catastrophe theory

NASA Astrophysics Data System (ADS)

Echkina, E. Y.; Inovenkov, I. N.; Nefedov, V. V.

2017-12-01

Magnetic field line reconnection (magnetic reconnection) is a phenomenon that occurs in space and laboratory plasma. Magnetic reconnection allows both the change the magnetic topology and the conversion of the magnetic energy into energy of fast particles. The critical point (critical line or plane in higher dimensional cases) of the magnetic field play an important role in process of magnetic reconnection, as in its neighborhood occurs a change of its topology of a magnetic field and redistribution of magnetic field energy. A lot of literature is devoted to the analytical and numerical investigation of the reconnection process. The main result of these investigations as the result of magnetic reconnection the current sheet is formed and the magnetic topology is changed. While the studies of magnetic reconnection in 2D and 3D configurations have a led to several important results, many questions remain open, including the behavior of a magnetic field in the neighborhood of a critical point of high order. The magnetic reconnection problem is closely related to the problem of the structural stability of vector fields. Since the magnetic field topology changes during both spontaneous and induced magnetic reconnection, it is natural to expect that the magnetic field should evolve from a structurally unstable into a structurally stable configuration. Note that, in this case, the phenomenon under analysis is more complicated since, during magnetic reconnection in a highly conducting plasma, we deal with the non-linear interaction between two vector fields: the magnetic field and the field of the plasma velocities. The aim of our article is to consider the process of magnetic reconnection and transformation of the magnetic topology from the viewpoint of catastrophe theory. Bifurcations in similar configurations (2D magnetic configuration with null high order point) with varying parameters were thoroughly discussed in a monograph by Poston and Stewart.

Simulation of profile evolution from ramp-up to ramp-down and optimization of tokamak plasma termination with the RAPTOR code

NASA Astrophysics Data System (ADS)

Teplukhina, A. A.; Sauter, O.; Felici, F.; Merle, A.; Kim, D.; the TCV Team; the ASDEX Upgrade Team; the EUROfusion MST1 Team

2017-12-01

The present work demonstrates the capabilities of the transport code RAPTOR as a fast and reliable simulator of plasma profiles for the entire plasma discharge, i.e. from ramp-up to ramp-down. This code focuses, at this stage, on the simulation of electron temperature and poloidal flux profiles using prescribed equilibrium and some kinetic profiles. In this work we extend the RAPTOR transport model to include a time-varying plasma equilibrium geometry and verify the changes via comparison with ATSRA code simulations. In addition a new ad hoc transport model based on constant gradients and suitable for simulations of L-H and H-L mode transitions has been incorporated into the RAPTOR code and validated with rapid simulations of the time evolution of the safety factor and the electron temperature over the entire AUG and TCV discharges. An optimization procedure for the plasma termination phase has also been developed during this work. We define the goal of the optimization as ramping down the plasma current as fast as possible while avoiding any disruptions caused by reaching physical or technical limits. Our numerical study of this problem shows that a fast decrease of plasma elongation during current ramp-down can help in reducing plasma internal inductance. An early transition from H- to L-mode allows us to reduce the drop in poloidal beta, which is also important for plasma MHD stability and control. This work shows how these complex nonlinear interactions can be optimized automatically using relevant cost functions and constraints. Preliminary experimental results for TCV are demonstrated.

Surface science in hernioplasty: The role of plasma treatments

NASA Astrophysics Data System (ADS)

Nisticò, Roberto; Magnacca, Giuliana; Martorana, Selanna

2017-10-01

The aim of this review is to clarify the importance of surface modifications induced in biomaterials for hernia-repair application. Starting from the pioneering experiences involving proto-materials as ancient prosthesis, a historical excursus between the biomaterials used in hernioplasty was realized. Subsequently, after the revolutionary discovery of stereoregular polymerization followed by the PP application in the biomedical field performed by the surgeon F. Usher, a comparative study on different hernia-repair meshes available was realized in order to better understand all the outstanding problems and possible future developments. Furthermore, since many unsolved problems on prosthetic devices implantation are linked to phenomena occurring at the interface between the biomaterials surface and the body fluids, the importance of surface science in hernioplasty was highlighted and case studies of new surface-modified generations of prosthesis presented. The results discussed in the following evidence how the surface study are becoming increasingly important for a proper knowledge of issues related to the interaction between the living matter and the artificial prostheses.

Magnetic Field Effects on Plasma Plumes

NASA Technical Reports Server (NTRS)

Ebersohn, F.; Shebalin, J.; Girimaji, S.; Staack, D.

2012-01-01

Here, we will discuss our numerical studies of plasma jets and loops, of basic interest for plasma propulsion and plasma astrophysics. Space plasma propulsion systems require strong guiding magnetic fields known as magnetic nozzles to control plasma flow and produce thrust. Propulsion methods currently being developed that require magnetic nozzles include the VAriable Specific Impulse Magnetoplasma Rocket (VASIMR) [1] and magnetoplasmadynamic thrusters. Magnetic nozzles are functionally similar to de Laval nozzles, but are inherently more complex due to electromagnetic field interactions. The two crucial physical phenomenon are thrust production and plasma detachment. Thrust production encompasses the energy conversion within the nozzle and momentum transfer to a spacecraft. Plasma detachment through magnetic reconnection addresses the problem of the fluid separating efficiently from the magnetic field lines to produce maximum thrust. Plasma jets similar to those of VASIMR will be studied with particular interest in dual jet configurations, which begin as a plasma loops between two nozzles. This research strives to fulfill a need for computational study of these systems and should culminate with a greater understanding of the crucial physics of magnetic nozzles with dual jet plasma thrusters, as well as astrophysics problems such as magnetic reconnection and dynamics of coronal loops.[2] To study this problem a novel, hybrid kinetic theory and single fluid magnetohydrodynamic (MHD) solver known as the Magneto-Gas Kinetic Method is used.[3] The solver is comprised of a "hydrodynamic" portion based on the Gas Kinetic Method and a "magnetic" portion that accounts for the electromagnetic behaviour of the fluid through source terms based on the resistive MHD equations. This method is being further developed to include additional physics such as the Hall effect. Here, we will discuss the current level of code development, as well as numerical simulation results

Study of Plasma Liner Driven Magnetized Target Fusion Via Advanced Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samulyak, Roman V.; Brookhaven National Lab.; Parks, Paul

The feasibility of the plasma liner driven Magnetized Target Fusion (MTF) via terascale numerical simulations will be assessed. In the MTF concept, a plasma liner, formed by merging of a number (60 or more) of radial, highly supersonic plasma jets, implodes on the target in the form of two compact plasma toroids, and compresses it to conditions of the fusion ignition. By avoiding major difficulties associated with both the traditional laser driven inertial confinement fusion and solid liner driven MTF, the plasma liner driven MTF potentially provides a low-cost and fast R&D path towards the demonstration of practical fusion energy.more » High fidelity numerical simulations of full nonlinear models associated with the plasma liner MTF using state-of-art numerical algorithms and terascale computing are necessary in order to resolve uncertainties and provide guidance for future experiments. At Stony Brook University, we have developed unique computational capabilities that ideally suite the MTF problem. The FronTier code, developed in collaboration with BNL and LANL under DOE funding including SciDAC for the simulation of 3D multi-material hydro and MHD flows, has beenbenchmarked and used for fundamental and engineering problems in energy science applications. We have performed 3D simulations of converging supersonic plasma jets, their merger and the formation of the plasma liner, and a study of the corresponding oblique shock problem. We have studied the implosion of the plasma liner on the magnetized plasma target by resolving Rayleigh-Taylor instabilities in 2D and 3D and other relevant physics and estimate thermodynamic conditions of the target at the moment of maximum compression and the hydrodynamic efficiency of the method.« less

Final Scientific Report: Experimental Investigation of Reconnection in a Line-tied Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forest, Cary

This grant used funding from the NSF/DoE Partnership on Plasma Science to investigate magnetic reconnection phenomena in a line-tied pinch experiment. The experiment was upgraded from a previous device intended to study fusion plasma-related instabilities to a new configuration capable of studying a number of new, previously unstudied configurations. A high spatial and time resolution array of magnetic probes was constructed to measure time evolving structures present as instability and turbulence developed. The most important new equilibrium made possible by this grant was a Zero-Net-Current equilibrium that models the footpoint twisting of solar flux tubes that occurs prior to solarmore » eruptions (flares and coronal mass ejections). This new equilibrium was successfully created in the lab, and it exhibited a host of instabilities. In particular, at low current when the equilibrium was not overly stressed, a saturated internal kink mode oscillation was observed. At high current, 2 D magnetic turbulence developed which we attribute to the lack of a equilibrium brought about by a subcritical transition to turbulence. A second set of experiments involved the turbulent interactions of a collection of flux tubes all being twisted independently, a problem known as the Parker Problem. Current profiles consisting of 2, 3 and 4 guns were used to impose a fine scale drive, and resulted in a new experimental platform in which the injection scale of the magnetic turbulence could be controlled. First experiments in this configuration support the conclusion that an inverse cascade of magnetic energy occurred which self-organized the plasma into a nearly axisymmetric current distribution.« less

Partition of Heating During Magnetic Reconnection: Role of Exhaust Velocity

NASA Astrophysics Data System (ADS)

Haggerty, C. C.; Shay, M.; Drake, J. F.; Phan, T.; Chasapis, A.; Cassak, P.; Malakit, K.

2017-12-01

The partition of released magnetic energy into ion and electron bulk flow and thermal energy is an important problem that has recently become under intense scrutiny in the magnetosphere and heliosphere. In the strong magnetic shear limit of magnetic reconnection (low guide field), the production of counter-streaming beams due to magnetic field line contraction plays an important role in heating the plasma. The contraction velocity or outflow velocity controls the magnitude of the heating. Although it is known that often the outflow velocity is less than the upstream Alfvén speed, an understanding of why this is so is lacking. We show that the outflow velocity in reconnection is reduced by the parallel ion exhaust temperature and derive a scaling relationship for this effect. This prediction is found to be consistent with both kinetic PIC simulations and MMS satellite observations. This scaling for the outflow is then applied to a general theory for plasma heating during magnetic reconnection.

Theoretical investigations of plasma processes in the ion bombardment thruster

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.

1975-01-01

A physical model for a thruster discharge was developed, consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field. The associated boundary-value problem for the coupled partial differential equations with mixed boundary conditions, which describe the electric potential and the plasma velocity fields, was solved in closed form. By means of quantum-mechanical perturbation theory, a formula for the number S(E) of atoms sputtered on the average by an ion of energy E was derived from first principles. The boundary-value problem describing the diffusion of the sputtered atoms through the surrounding rarefied electron-ion plasma to the system surfaces of ion propulsion systems was formulated and treated analytically. It is shown that outer boundary-value problems of this type lead to a complex integral equation, which requires numerical resolution.

Hydrogen Plasma Processing of Iron Ore

NASA Astrophysics Data System (ADS)

Sabat, Kali Charan; Murphy, Anthony B.

2017-06-01

Iron is currently produced by carbothermic reduction of oxide ores. This is a multiple-stage process that requires large-scale equipment and high capital investment, and produces large amounts of CO2. An alternative to carbothermic reduction is reduction using a hydrogen plasma, which comprises vibrationally excited molecular, atomic, and ionic states of hydrogen, all of which can reduce iron oxides, even at low temperatures. Besides the thermodynamic and kinetic advantages of a hydrogen plasma, the byproduct of the reaction is water, which does not pose any environmental problems. A review of the theory and practice of iron ore reduction using a hydrogen plasma is presented. The thermodynamic and kinetic aspects are considered, with molecular, atomic and ionic hydrogen considered separately. The importance of vibrationally excited hydrogen molecules in overcoming the activation energy barriers, and in transferring energy to the iron oxide, is emphasized. Both thermal and nonthermal plasmas are considered. The thermophysical properties of hydrogen and argon-hydrogen plasmas are discussed, and their influence on the constriction and flow in the of arc plasmas is considered. The published R&D on hydrogen plasma reduction of iron oxide is reviewed, with both the reduction of molten iron ore and in-flight reduction of iron ore particles being considered. Finally, the technical and economic feasibility of the process are discussed. It is shown that hydrogen plasma processing requires less energy than carbothermic reduction, mainly because pelletization, sintering, and cokemaking are not required. Moreover, the formation of the greenhouse gas CO2 as a byproduct is avoided. In-flight reduction has the potential for a throughput at least equivalent to the blast furnace process. It is concluded that hydrogen plasma reduction of iron ore is a potentially attractive alternative to standard methods.

The Role of Higher-Order Modes on the Electromagnetic Whistler-Cyclotron Wave Fluctuations of Thermal and Non-Thermal Plasmas

NASA Technical Reports Server (NTRS)

Vinas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto; Araneda, Jamie A.

2014-01-01

Two fundamental challenging problems of laboratory and astrophysical plasmas are the understanding of the relaxation of a collisionless plasmas with nearly isotropic velocity distribution functions and the resultant state of nearly equipartition energy density with electromagnetic plasma turbulence. Here, we present the results of a study which shows the role that higher-order-modes play in limiting the electromagnetic whistler-like fluctuations in a thermal and non-thermal plasma. Our main results show that for a thermal plasma the magnetic fluctuations are confined by regions that are bounded by the least-damped higher order modes. We further show that the zone where the whistler-cyclotron normal modes merges the electromagnetic fluctuations shifts to longer wavelengths as the beta(sub e) increases. This merging zone has been interpreted as the beginning of the region where the whistler-cyclotron waves losses their identity and become heavily damped while merging with the fluctuations. Our results further indicate that in the case of nonthermal plasmas, the higher-order modes do not confine the fluctuations due to the effective higher-temperature effects and the excess of suprathermal plasma particles. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic bi-Maxwellian and Tsallis-kappa-like magnetized electron-proton plasma. Our results indicate that the spontaneously emitted electromagnetic fluctuations are in fact enhanced over these quasi modes suggesting that such modes play an important role in the emission and absorption of electromagnetic fluctuations in thermal or quasi-thermal plasmas.

Surface density of accumulated electrons on walls in contact with a plasma

NASA Technical Reports Server (NTRS)

De, B. R.

1975-01-01

It is shown that the surface density of accumulated electrons on a wall in contact with a plasma can be expressed as a simple function of the Debye shielding distance in the plasma. The result may have applications to problems involving objects immersed in a space plasma.

Application of Dynamic Logic Algorithm to Inverse Scattering Problems Related to Plasma Diagnostics

NASA Astrophysics Data System (ADS)

Perlovsky, L.; Deming, R. W.; Sotnikov, V.

2010-11-01

In plasma diagnostics scattering of electromagnetic waves is widely used for identification of density and wave field perturbations. In the present work we use a powerful mathematical approach, dynamic logic (DL), to identify the spectra of scattered electromagnetic (EM) waves produced by the interaction of the incident EM wave with a Langmuir soliton in the presence of noise. The problem is especially difficult since the spectral amplitudes of the noise pattern are comparable with the amplitudes of the scattered waves. In the past DL has been applied to a number of complex problems in artificial intelligence, pattern recognition, and signal processing, resulting in revolutionary improvements. Here we demonstrate its application to plasma diagnostic problems. [4pt] Perlovsky, L.I., 2001. Neural Networks and Intellect: using model-based concepts. Oxford University Press, New York, NY.

Predator-prey dynamics stabilised by nonlinearity explain oscillations in dust-forming plasmas

PubMed Central

Ross, A. E.; McKenzie, D. R.

2016-01-01

Dust-forming plasmas are ionised gases that generate particles from a precursor. In nature, dust-forming plasmas are found in flames, the interstellar medium and comet tails. In the laboratory, they are valuable in generating nanoparticles for medicine and electronics. Dust-forming plasmas exhibit a bizarre, even puzzling behaviour in which they oscillate with timescales of seconds to minutes. Here we show how the problem of understanding these oscillations may be cast as a predator-prey problem, with electrons as prey and particles as predators. The addition of a nonlinear loss term to the classic Lotka-Volterra equations used for describing the predator-prey problem in ecology not only stabilises the oscillations in the solutions for the populations of electrons and particles in the plasma but also explains the behaviour in more detail. The model explains the relative phase difference of the two populations, the way in which the frequency of the oscillations varies with the concentration of the precursor gas, and the oscillations of the light emission, determined by the populations of both species. Our results demonstrate the value of adopting an approach to a complex physical science problem that has been found successful in ecology, where complexity is always present. PMID:27046237

Plasma metabolomics profiling of maintenance hemodialysis based on capillary electrophoresis - time of flight mass spectrometry.

PubMed

Liu, Shuxin; Wang, Lichao; Hu, Chunxiu; Huang, Xin; Liu, Hong; Xuan, Qiuhui; Lin, Xiaohui; Peng, Xiaojun; Lu, Xin; Chang, Ming; Xu, Guowang

2017-08-15

Uremia has been a rapidly increasing health problem in China. Hemodialysis (HD) is the main renal replacement therapy for uremia. The results of large-scale clinical trials have shown that the HD pattern is crucial for long-term prognosis of maintenance hemodialysis (MHD) in uremic patients. Plasma metabolism is very important for revealing the biological insights linked to the therapeutic effects of the HD pattern on uremia. Alteration of plasma metabolites in uremic patients in response to HD therapy has been reported. However, HD-pattern-dependent changes in plasma metabolites remain poorly understood. To this end, a capillary electrophoresis-time of flight mass spectrometry (CE-TOF/MS)-based metabolomics method was performed to systemically study the differences between HD and high flux hemodialysis (HFD) on plasma metabolite changes in patients. Three hundred and one plasma samples from three independent human cohorts (i.e., healthy controls, patients with pre-HD/post-HD, and patients with pre-HFD/post-HFD) were used in this study. Metabolites significantly changed (p < 0.05) after a single HD or HFD process. However, 11 uremic retention solutes could be more efficiently removed by HFD. Our findings indicate that a CE-TOF/MS-based metabolomics approach is promising for providing novel insights into understanding the effects of different dialysis methods on metabolite alterations of uremia.

A rapid method for selecting suitable animal species for studying pathogen interactions with plasma protein ligands in vivo.

PubMed

Naudin, Clément; Schumski, Ariane; Salo-Ahen, Outi M H; Herwald, Heiko; Smeds, Emanuel

2017-05-01

Species tropism constitutes a serious problem for developing relevant animal models of infection. Human pathogens can express virulence factors that show specific selectivity to human proteins, while their affinity for orthologs from other species can vary significantly. Suitable animal species must be used to analyse whether virulence factors are potential targets for drug development. We developed an assay that rapidly predicts applicable animal species for studying virulence factors binding plasma proteins. We used two well-characterized Staphylococcus aureus proteins, SSL7 and Efb, to develop an ELISA-based inhibition assay using plasma from different animal species. The interaction between SSL7 and human C5 and the binding of Efb to human fibrinogen and human C3 was studied. Affinity experiments and Western blot analyses were used to validate the assay. Human, monkey and cat plasma interfered with binding of SSL7 to human C5. Binding of Efb to human fibrinogen was blocked in human, monkey, gerbil and pig plasma, while human, monkey, gerbil, rabbit, cat and guinea pig plasma inhibited the binding of Efb to human C3. These results emphasize the importance of choosing correct animal models, and thus, our approach is a rapid and cost-effective method that can be used to prevent unnecessary animal experiments. © 2017 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Time-nonlocal kinetic equations, jerk and hyperjerk in plasmas and solar physics

NASA Astrophysics Data System (ADS)

El-Nabulsi, Rami Ahmad

2018-06-01

The simulation and analysis of nonlocal effects in fluids and plasmas is an inherently complicated problem due to the massive breadth of physics required to describe the nonlocal dynamics. This is a multi-physics problem that draws upon various miscellaneous fields, such as electromagnetism and statistical mechanics. In this paper we strive to focus on one narrow but motivating mathematical way: the derivation of nonlocal plasma-fluid equations from a generalized nonlocal Liouville derivative operator motivated from Suykens's nonlocal arguments. The paper aims to provide a guideline toward modeling nonlocal effects occurring in plasma-fluid systems by means of a generalized nonlocal Boltzmann equation. The generalized nonlocal equations of fluid dynamics are derived and their implications in plasma-fluid systems are addressed, discussed and analyzed. Three main topics were discussed: Landau damping in plasma electrodynamics, ideal MHD and solar wind. A number of features were revealed, analyzed and confronted with recent research results and observations.

Assessment of quasi-linear effect of RF power spectrum for enabling lower hybrid current drive in reactor plasmas

NASA Astrophysics Data System (ADS)

Cesario, Roberto; Cardinali, Alessandro; Castaldo, Carmine; Amicucci, Luca; Ceccuzzi, Silvio; Galli, Alessandro; Napoli, Francesco; Panaccione, Luigi; Santini, Franco; Schettini, Giuseppe; Tuccillo, Angelo Antonio

2017-10-01

The main research on the energy from thermonuclear fusion uses deuterium plasmas magnetically trapped in toroidal devices. To suppress the turbulent eddies that impair thermal insulation and pressure tight of the plasma, current drive (CD) is necessary, but tools envisaged so far are unable accomplishing this task while efficiently and flexibly matching the natural current profiles self-generated at large radii of the plasma column [1-5]. The lower hybrid current drive (LHCD) [6] can satisfy this important need of a reactor [1], but the LHCD system has been unexpectedly mothballed on JET. The problematic extrapolation of the LHCD tool at reactor graded high values of, respectively, density and temperatures of plasma has been now solved. The high density problem is solved by the FTU (Frascati Tokamak Upgrade) method [7], and solution of the high temperature one is presented here. Model results based on quasi-linear (QL) theory evidence the capability, w.r.t linear theory, of suitable operating parameters of reducing the wave damping in hot reactor plasmas. Namely, using higher RF power densities [8], or a narrower antenna power spectrum in refractive index [9,10], the obstacle for LHCD represented by too high temperature of reactor plasmas should be overcome. The former method cannot be used for routinely, safe antenna operations, Thus, only the latter key is really exploitable in a reactor. The proposed solutions are ultimately necessary for viability of an economic reactor.

Arbitrary amplitude ion-acoustic solitary waves in electronegative plasmas with electrons featuring Tsallis distribution

NASA Astrophysics Data System (ADS)

Ghebache, Siham; Tribeche, Mouloud

2017-10-01

The problem of arbitrary amplitude ion-acoustic solitary waves (IASWs), which accompany electronegative plasmas having positive ions, negative ions, and nonextensive electrons is addressed. The energy integral equation with a new Sagdeev potential is analyzed to examine the existence regions of the IASWs. Different types of electronegative plasmas inspired from the experimental studies of Ichiki et al. (2001) are discussed. Our results show that in such plasmas IASWs, the amplitude and nature of which depend sensitively on the mass and density ratio of the positive and negative ions as well as the q-nonextensive parameter, can exist. Interestingly, one finds that our plasma model supports the coexistence of smooth rarefactive and spiky compressive IASWs. Our results complement and provide new insights on previously published findings on this problem.

Role of poloidal flows on the particle confinement time in a simple toroidal device : an experimental study

NASA Astrophysics Data System (ADS)

Kumar, Umesh; Ganesh, R.; Saxena, Y. C.; Thatipamula, Shekar G.; Sathyanarayana, K.; Raju, Daniel

2017-10-01

In magnetized toroidal devices without rotational transform also known as Simple Magnetized Torus (SMT). The device BETA at the IPR is one such SMT with a major radius of 45 cm, minor radius of 15 cm and a maximum toroidal field of 0.1 Tesla. Understanding confinement in such helical configurations is an important problem both for fundamental plasma physics and for Tokamak edge physics. In a recent series of experiments it was demonstrated experimentally that the mean plasma profiles, fluctuation, flow and turbulence depend crucially on the parallel connection length, which was controlled by external vertical field. In the present work, we report our experimental findings, wherein we measure the particle confinement time for hot cathode discharge and ECRH discharge, with variation in parallel connection length. As ECRH plasma don't have mean electric field and hence the poloidal rotation of plasma is absent. However, in hot cathode discharge, there exist strong poloidal flows due to mean electric field. An experimental comparison of these along with theoretical model with variation in connection length will be presented. We also present experimental measurements of variation of plasma confinement time with mass as well as the ratio of vertical field to toroidal magnetic field.

Unresolved Issues With Inner Magnetosphere-Ionosphere Coupling

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Khazanov, G.

2004-01-01

Dipolarization and the release of stored magnetic energy is strongly evident in the energized plasma sheet electrons and ions injected earthward from the magnetotail. While some of these plasma are presumed lost into the dayside magnetosheath, much of the energy is dissipated into the ionosphere through electric currents, through collisions into low energy plasma, and into plasma waves, which then go on to heat and energize plasma of the inner magnetosphere. Many mechanisms for the transfer of energy and the consequences to inner magnetospheric plasma populations have been proposed. The sophistication of theoretical models to represent the interdependencies between plasma populations is rapidly increasing. However without the restraint and reality imposed on theory by relevant measurements, the degree to which specific mechanisms participate in the exchange of energy as a function of location and time cannot be known. ORBITALS offers this capability. Some of the outstanding problems in inner magnetospheric physics and the opportunities presented by the ORBITAL concept to solve problems will be discussed.

Teaching an Old Dog an Old Trick: FREE-FIX and Free-Boundary Axisymmetric MHD Equilibrium

NASA Astrophysics Data System (ADS)

Guazzotto, Luca

2015-11-01

A common task in plasma physics research is the calculation of an axisymmetric equilibrium for tokamak modeling. The main unknown of the problem is the magnetic poloidal flux ψ. The easiest approach is to assign the shape of the plasma and only solve the equilibrium problem in the plasma / closed-field-lines region (the ``fixed-boundary approach''). Often, one may also need the vacuum fields, i.e. the equilibrium in the open-field-lines region, requiring either coil currents or ψ on some closed curve outside the plasma to be assigned (the ``free-boundary approach''). Going from one approach to the other is a textbook problem, involving the calculation of Green's functions and surface integrals in the plasma. However, no tools are readily available to perform this task. Here we present a code (FREE-FIX) to compute a boundary condition for a free-boundary equilibrium given only the corresponding fixed-boundary equilibrium. An improvement to the standard solution method, allowing for much faster calculations, is presented. Applications are discussed. PPPL fund 245139 and DOE grant G00009102.

TRANSPORT EQUATION OF A PLASMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balescu, R.

1960-10-01

It is shown that the many-body problem in plasmas can be handled explicitly. An equation describing the collective effects of the problem is derived. For simplicity, a onecomponent gas is considered in a continuous neutralizing background. The tool for handling the problem is provided by the general theory of irreversible processes in gases. The equation derived describes the interaction of electrons which are"dressed" by a polarization cloud. The polarization cloud differs from the Debye cloud. (B.O.G.)

On the performance of exponential integrators for problems in magnetohydrodynamics

NASA Astrophysics Data System (ADS)

Einkemmer, Lukas; Tokman, Mayya; Loffeld, John

2017-02-01

Exponential integrators have been introduced as an efficient alternative to explicit and implicit methods for integrating large stiff systems of differential equations. Over the past decades these methods have been studied theoretically and their performance was evaluated using a range of test problems. While the results of these investigations showed that exponential integrators can provide significant computational savings, the research on validating this hypothesis for large scale systems and understanding what classes of problems can particularly benefit from the use of the new techniques is in its initial stages. Resistive magnetohydrodynamic (MHD) modeling is widely used in studying large scale behavior of laboratory and astrophysical plasmas. In many problems numerical solution of MHD equations is a challenging task due to the temporal stiffness of this system in the parameter regimes of interest. In this paper we evaluate the performance of exponential integrators on large MHD problems and compare them to a state-of-the-art implicit time integrator. Both the variable and constant time step exponential methods of EPIRK-type are used to simulate magnetic reconnection and the Kevin-Helmholtz instability in plasma. Performance of these methods, which are part of the EPIC software package, is compared to the variable time step variable order BDF scheme included in the CVODE (part of SUNDIALS) library. We study performance of the methods on parallel architectures and with respect to magnitudes of important parameters such as Reynolds, Lundquist, and Prandtl numbers. We find that the exponential integrators provide superior or equal performance in most circumstances and conclude that further development of exponential methods for MHD problems is warranted and can lead to significant computational advantages for large scale stiff systems of differential equations such as MHD.

ICRH antenna S-matrix measurements and plasma coupling characterisation at JET

NASA Astrophysics Data System (ADS)

Monakhov, I.; Jacquet, P.; Blackman, T.; Bobkov, V.; Dumortier, P.; Helou, W.; Lerche, E.; Kirov, K.; Milanesio, D.; Maggiora, R.; Noble, C.; Contributors, JET

2018-04-01

The paper is dedicated to the characterisation of multi-strap ICRH antenna coupling to plasma. Relevance of traditional concept of coupling resistance to antennas with mutually coupled straps is revised and the importance of antenna port excitation consistency for application of the concept is highlighted. A method of antenna S-matrix measurement in presence of plasma is discussed allowing deeper insight into the problem of antenna-plasma coupling. The method is based entirely on the RF plant hardware and control facilities available at JET and it involves application of variable phasing between the antenna straps during the RF plant operations at  >100 kW. Unlike traditional techniques relying on low-power (~10 mW) network analysers, the applied antenna voltage amplitudes are relevant to practical conditions of ICRH operations; crucially, they are high enough to minimise possible effects of antenna loading non-linearity due to the RF sheath effects and other phenomena which could affect low-power measurements. The method has been successfully applied at JET to conventional 4-port ICRH antennas energised at frequencies of 33 MHz, 42 MHz and 51 MHz during L-mode plasma discharges while different gas injection modules (GIMs) were used to maintain comparable plasma densities during the pulses. The S-matrix assessment and its subsequent processing yielding ‘global’ antenna coupling resistances in conditions of equalised port maximum voltages allowed consistent description of antenna coupling to plasma at different strap phasing, operational frequencies and applied GIMs. Comprehensive experimental characterisation of mutually coupled antenna straps in presence of plasma also provided a unique opportunity for in-depth verification of TOPICA computer simulations.

A Numerical Characterization of the Gravito-Electrostatic Sheath Equilibrium Structure in Solar Plasma

NASA Astrophysics Data System (ADS)

Karmakar, Pralay Kumar

This article describes the equilibrium structure of the solar interior plasma (SIP) and solar wind plasma (SWP) in detail under the framework of the gravito-electrostatic sheath (GES) model. This model gives a precise definition of the solar surface boundary (SSB), surface origin mechanism of the subsonic SWP, and its supersonic acceleration. Equilibrium parameters like plasma potential, self-gravity, population density, flow, their gradients, and all the relevant inhomogeneity scale lengths are numerically calculated and analyzed as an initial value problem. Physical significance of the structure condition for the SSB is discussed. The plasma oscillation and Jeans time scales are also plotted and compared. In addition, different coupling parameters, and electric current profiles are also numerically studied. The current profiles exhibit an important behavior of directional reversibility, i.e., an electrodynamical transition from negative to positive value. It occurs beyond a few Jeans lengths away from the SSB. The virtual spherical surface lying at the current reversal point, where the net current becomes zero, has the property of a floating surface behavior of the real physical wall. Our investigation indicates that the SWP behaves as an ion current-carrying plasma system. The basic mechanism behind the GES formation and its distinctions from conventional plasma sheath are discussed. The electromagnetic properties of the Sun derived from our model with the most accurate available inputs are compared with those of others. These results are useful as an input element to study the properties of the linear and nonlinear dynamics of various solar plasma waves, oscillations and instabilities.

Computational study of arc discharges: Spark plug and railplug ignitors

NASA Astrophysics Data System (ADS)

Ekici, Ozgur

A theoretical study of electrical arc discharges that focuses on the discharge processes in spark plug and railplug ignitors is presented. The aim of the study is to gain a better understanding of the dynamics of electrical discharges, more specifically the transfer of electrical energy into the gas and the effect of this energy transfer on the flow physics. Different levels of computational models are presented to investigate the types of arc discharges seen in spark plugs and railplugs (i.e., stationary and moving arc discharges). Better understanding of discharge physics is important for a number of applications. For example, improved fuel economy under the constraint of stricter emissions standards and improved plug durability are important objectives of current internal combustion engine designs. These goals can be achieved by improving the existing systems (spark plug) and introducing more sophisticated ignition systems (railplug). In spite of the fact spark plug and railplug ignitors are the focus of this work, the methods presented in this work can be extended to study the discharges found in other applications such as plasma torches, laser sparks, and circuit breakers. The system of equations describing the physical processes in an air plasma is solved using computational fluid dynamics codes to simulate thermal and flow fields. The evolution of the shock front, temperature, pressure, density, and flow of a plasma kernel were investigated for both stationary and moving arcs. Arc propagation between the electrodes under the effects of gas dynamics and electromagnetic processes was studied for moving arcs. The air plasma is regarded as a continuum, single substance material in local thermal equilibrium. Thermophysical properties of high temperature air are used to take into consideration the important processes such as dissociation and ionization. The different mechanisms and the relative importance of several assumptions in gas discharges and thermal plasma modeling were investigated. Considering the complex nature of the studied problem, the computational models aid in analyzing the analytical theory and serve as relatively inexpensive tools when compared to experiments in design process.

Nonlinear Excitation of Acoustic Modes by Large Amplitude Alfvén waves in the Large Plasma Device (LAPD)

NASA Astrophysics Data System (ADS)

Dorfman, S. E.; Carter, T. A.; Pribyl, P.; Tripathi, S.; Van Compernolle, B.; Vincena, S. T.; Sydora, R. D.

2013-12-01

Alfvén waves, a fundamental mode of magnetized plasmas, are ubiquitous in space plasmas. While the linear behavior of these waves has been extensively studied [1], non-linear effects are important in many real systems, including the solar corona and solar wind. In particular, a parametric decay process in which a large amplitude Alfvén wave decays into an ion acoustic wave and backward propagating Alfvén wave may play an important role in the coronal heating problem. Specifically, the decay of large-amplitude Alfvén waves propagating outward from the photosphere could lead to heating of the corona by the daughter ion acoustic modes [2]. As direct observational evidence of parametric decay is limited [3], laboratory experiments may play an important role in validating simple theoretical predictions and aiding in the interpretation of space measurements. Recent counter-propagating Alfvén wave experiments in the Large Plasma Device (LAPD) have recorded the first laboratory observation of the Alfvén-acoustic mode coupling at the heart of this parametric decay instability [4]. A resonance in the beat wave response produced by the two launched Alfvén waves is observed and is identified as a damped ion acoustic mode based on the measured dispersion relation. Other properties of the interaction including the spatial profile of the beat mode and response amplitude are also consistent with theoretical predictions for a three-wave interaction driven by a nonlinear ponderomotive force. Strong damping observed after the pump Alfvén waves are turned off is under investigation; a novel ion acoustic wave launcher is under development to launch the mode directly for damping studies. New experiments also aim to identify decay instabilities from a single large-amplitude Alfvén wave. In conjunction with these experiments, gyrokinetic simulation efforts are underway to scope out the relevant parameter space. [1] W. Gekelman, et. al., Phys. Plasmas 18, 055501 (2011). [2] F. Pruneti, F and M. Velli, ESA Spec. Pub. 404, 623 (1997). [3] S. R. Spangler, et. al., Phys. Plasmas 4, 846 (1997). [4] S. Dorfman and T. Carter, Phys. Rev. Lett. 110, 195001 (2013).

Physics of the inner heliosphere: Mechanisms, models and observational signatures

NASA Technical Reports Server (NTRS)

Withbroe, George L.

1987-01-01

Selected problems concerned with the important physical processes that occur in the corona and solar wind acceleration region, particularly time dependent phenomena were studied. Both the physics of the phenomena and the resultant effects on observational signatures, particularly spectroscopic signatures were also studied. Phenomena under study include: wave motions, particularly Alfven and fast mode waves; the formation of standing shocks in the inner heliosphere as a result of momentum and/or heat addition to the wind; and coronal transient phenomena where momentum and/or heat are deposited in the corona to produce transient plasma heating and/or mass ejection. The development of theoretical models for the inner heliosphere, the theoretical investigation of spectroscopic plasma diagnostics for this region, and the analysis of existing skylab and other relevant data are also included.

Vector processing efficiency of plasma MHD codes by use of the FACOM 230-75 APU

NASA Astrophysics Data System (ADS)

Matsuura, T.; Tanaka, Y.; Naraoka, K.; Takizuka, T.; Tsunematsu, T.; Tokuda, S.; Azumi, M.; Kurita, G.; Takeda, T.

1982-06-01

In the framework of pipelined vector architecture, the efficiency of vector processing is assessed with respect to plasma MHD codes in nuclear fusion research. By using a vector processor, the FACOM 230-75 APU, the limit of the enhancement factor due to parallelism of current vector machines is examined for three numerical codes based on a fluid model. Reasonable speed-up factors of approximately 6,6 and 4 times faster than the highly optimized scalar version are obtained for ERATO (linear stability code), AEOLUS-R1 (nonlinear stability code) and APOLLO (1-1/2D transport code), respectively. Problems of the pipelined vector processors are discussed from the viewpoint of restructuring, optimization and choice of algorithms. In conclusion, the important concept of "concurrency within pipelined parallelism" is emphasized.

Space solar power stations. Problems of energy generation and using its on the earth surface and nearest cosmos

NASA Astrophysics Data System (ADS)

Sinkevich, OA; Gerasimov, DN; Glazkov, VV

2017-11-01

Three important physical and technical problems for solar power stations (SPS) are considered: collection of solar energy and effective conversion of this energy to electricity in space power stations, energy transportation by the microwave beam to the Earth surface and direct utilization of the microwave beam energy for global environmental problems. Effectiveness of solar energy conversion into electricity in space power stations using gas and steam turbines plants, and magneto-hydrodynamic generator (MHDG) are analyzed. The closed cycle MHDG working on non-equilibrium magnetized plasmas of inert gases seeded with the alkaline metal vapors are considered. The special emphases are placed on MHDG and gas-turbine installations that are operating without compressor. Also opportunities for using the produced by space power stations energy for ecological needs on Earth and in Space are discussed.

Post-column infusion study of the 'dosing vehicle effect' in the liquid chromatography/tandem mass spectrometric analysis of discovery pharmacokinetic samples.

PubMed

Shou, Wilson Z; Naidong, Weng

2003-01-01

It has become increasingly popular in drug development to conduct discovery pharmacokinetic (PK) studies in order to evaluate important PK parameters of new chemical entities (NCEs) early in the discovery process. In these studies, dosing vehicles are typically employed in high concentrations to dissolve the test compounds in dose formulations. This can pose significant problems for the liquid chromatography/tandem mass spectrometric (LC/MS/MS) analysis of incurred samples due to potential signal suppression of the analytes caused by the vehicles. In this paper, model test compounds in rat plasma were analyzed using a generic fast gradient LC/MS/MS method. Commonly used dosing vehicles, including poly(ethylene glycol) 400 (PEG 400), polysorbate 80 (Tween 80), hydroxypropyl beta-cyclodextrin, and N,N-dimethylacetamide, were fortified into rat plasma at 5 mg/mL before extraction. Their effects on the sample analysis results were evaluated by the method of post-column infusion. Results thus obtained indicated that polymeric vehicles such as PEG 400 and Tween 80 caused significant suppression (> 50%, compared with results obtained from plasma samples free from vehicles) to certain analytes, when minimum sample cleanup was used and the analytes happened to co-elute with the vehicles. Effective means to minimize this 'dosing vehicle effect' included better chromatographic separations, better sample cleanup, and alternative ionization methods. Finally, a real-world example is given to illustrate the suppression problem posed by high levels of PEG 400 in sample analysis, and to discuss steps taken in overcoming the problem. A simple but effective means of identifying a 'dosing vehicle effect' is also proposed. Copyright 2003 John Wiley & Sons, Ltd.

Differential Protein Expression in the Hemolymph of Bithynia siamensis goniomphalos Infected with Opisthorchis viverrini

PubMed Central

Suwannatrai, Kulwadee; Suwannatrai, Apiporn; Tabsripair, Pairat; Welbat, Jariya Umka; Tangkawattana, Sirikachorn; Cantacessi, Cinzia; Mulvenna, Jason; Tesana, Smarn; Loukas, Alex

2016-01-01

Bithynia siamensis goniomphalos is a freshwater snail that serves as the first intermediate host of the human liver fluke Opisthorchis viverrini. This parasite is a major public health problem in different countries throughout the Greater Mekong sub-region (Thailand, southern Vietnam, Lao PDR and Cambodia). Chronic O. viverrini infection also results in a gradual increase of fibrotic tissues in the biliary tract that are associated with hepatobiliary diseases and contribute to cholangiocarcinoma (a fatal type of bile duct cancer). Infectivity of the parasite in the snail host is strongly correlated with destruction of helminths by the snail’s innate immune system, composed of cellular (hemocyte) and humoral (plasma) defense factors. To better understand this important host-parasite interface we applied sequential window acquisition of all theoretical spectra mass spectrometry (SWATH-MS) to identify and quantify the proteins from the hemolymph of B. siamensis goniomphalos experimentally infected with O. viverrini and compare them to non-infected snails (control group). A total of 362 and 242 proteins were identified in the hemocytes and plasma, respectively. Of these, 145 and 117 proteins exhibited significant differences in expression upon fluke infection in hemocytes and plasma, respectively. Among the proteins with significantly different expression patterns, we found proteins related to immune response (up-regulated in both hemocyte and plasma of infected snails) and proteins belonging to the structural and motor group (mostly down-regulated in hemocytes but up-regulated in plasma of infected snails). The proteins identified and quantified in this work will provide important information for the understanding of the factors involved in snail defense against O. viverrini and might facilitate the development of new strategies to control O. viverrini infection in endemic areas. PMID:27893749

Changing the surface properties on naval steel as result of non-thermal plasma treatment

NASA Astrophysics Data System (ADS)

Hnatiuc, B.; Sabău, A.; Dumitrache, C. L.; Hnatiuc, M.; Crețu, M.; Astanei, D.

2016-08-01

The problem of corrosion, related to Biofouling formation, is an issue with very high importance in the maritime domain. According to new rules, the paints and all the technologies for the conditioning of naval materials must fulfil more restrictive environmental conditions. In order to solve this issue, different new clean technologies have been proposed. Among them, the use of non-thermal plasmas produced at atmospheric pressure plays a very important role. This study concerns the opportunity of plasma treatment for preparation or conditioning of naval steel OL36 type. The plasma reactors chosen for the experiments can operate at atmospheric pressure and are easy to use in industrial conditions. They are based on electrical discharges GlidArc and Spark, which already proved their efficiency for the surface activation or even for coatings of the surface. The non-thermal character of the plasma is ensured by a gas flow blown through the electrical discharges. One power supply has been used for reactors that provide a 5 kV voltage and a maximum current of 100 mA. The modifications of the surface properties and composition have been studied by XPS technique (X-ray Photoelectron Spectroscopy). There were taken into consideration 5 samples: 4 of them undergoing a Mini-torch plasma, a Gliding Spark, a GlidArc with dry air and a GlidArc with CO2, respectively the fifth sample which is the untreated witness. Before the plasma treatment, samples of naval steel were processed in order to obtain mechanical gloss. The time of treatment was chosen to 12 minutes. In the spectroscopic analysis, done on a ULVAC-PHI, Inc. PHI 5000 Versa Probe scanning XPS microprobe, a monocromated Al Kα X-ray source with a spot size of 100 μm2 was used to scan each sample while the photoelectrons were collected at a 45-degree take-off angle. Differences were found between atomic concentrations in each individual case, which proves that the active species produced by each type of plasma affects the surface properties of the treated naval steel.

Initial Simulations of RF Waves in Hot Plasmas Using the FullWave Code

NASA Astrophysics Data System (ADS)

Zhao, Liangji; Svidzinski, Vladimir; Spencer, Andrew; Kim, Jin-Soo

2017-10-01

FullWave is a simulation tool that models RF fields in hot inhomogeneous magnetized plasmas. The wave equations with linearized hot plasma dielectric response are solved in configuration space on adaptive cloud of computational points. The nonlocal hot plasma dielectric response is formulated by calculating the plasma conductivity kernel based on the solution of the linearized Vlasov equation in inhomogeneous magnetic field. In an rf field, the hot plasma dielectric response is limited to the distance of a few particles' Larmor radii, near the magnetic field line passing through the test point. The localization of the hot plasma dielectric response results in a sparse matrix of the problem thus significantly reduces the size of the problem and makes the simulations faster. We will present the initial results of modeling of rf waves using the Fullwave code, including calculation of nonlocal conductivity kernel in 2D Tokamak geometry; the interpolation of conductivity kernel from test points to adaptive cloud of computational points; and the results of self-consistent simulations of 2D rf fields using calculated hot plasma conductivity kernel in a tokamak plasma with reduced parameters. Work supported by the US DOE ``SBIR program.

A full-angle Monte-Carlo scattering technique including cumulative and single-event Rutherford scattering in plasmas [Theory of cumulative large-angle collisions in plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higginson, Drew P.

Here, we describe and justify a full-angle scattering (FAS) method to faithfully reproduce the accumulated differential angular Rutherford scattering probability distribution function (pdf) of particles in a plasma. The FAS method splits the scattering events into two regions. At small angles it is described by cumulative scattering events resulting, via the central limit theorem, in a Gaussian-like pdf; at larger angles it is described by single-event scatters and retains a pdf that follows the form of the Rutherford differential cross-section. The FAS method is verified using discrete Monte-Carlo scattering simulations run at small timesteps to include each individual scattering event.more » We identify the FAS regime of interest as where the ratio of temporal/spatial scale-of-interest to slowing-down time/length is from 10 -3 to 0.3–0.7; the upper limit corresponds to Coulomb logarithm of 20–2, respectively. Two test problems, high-velocity interpenetrating plasma flows and keV-temperature ion equilibration, are used to highlight systems where including FAS is important to capture relevant physics.« less

A finite element method with overlapping meshes for free-boundary axisymmetric plasma equilibria in realistic geometries

NASA Astrophysics Data System (ADS)

Heumann, Holger; Rapetti, Francesca

2017-04-01

Existing finite element implementations for the computation of free-boundary axisymmetric plasma equilibria approximate the unknown poloidal flux function by standard lowest order continuous finite elements with discontinuous gradients. As a consequence, the location of critical points of the poloidal flux, that are of paramount importance in tokamak engineering, is constrained to nodes of the mesh leading to undesired jumps in transient problems. Moreover, recent numerical results for the self-consistent coupling of equilibrium with resistive diffusion and transport suggest the necessity of higher regularity when approximating the flux map. In this work we propose a mortar element method that employs two overlapping meshes. One mesh with Cartesian quadrilaterals covers the vacuum chamber domain accessible by the plasma and one mesh with triangles discretizes the region outside. The two meshes overlap in a narrow region. This approach gives the flexibility to achieve easily and at low cost higher order regularity for the approximation of the flux function in the domain covered by the plasma, while preserving accurate meshing of the geometric details outside this region. The continuity of the numerical solution in the region of overlap is weakly enforced by a mortar-like mapping.

A full-angle Monte-Carlo scattering technique including cumulative and single-event Rutherford scattering in plasmas [Theory of cumulative large-angle collisions in plasmas

DOE PAGES

Higginson, Drew P.

2017-08-12

Here, we describe and justify a full-angle scattering (FAS) method to faithfully reproduce the accumulated differential angular Rutherford scattering probability distribution function (pdf) of particles in a plasma. The FAS method splits the scattering events into two regions. At small angles it is described by cumulative scattering events resulting, via the central limit theorem, in a Gaussian-like pdf; at larger angles it is described by single-event scatters and retains a pdf that follows the form of the Rutherford differential cross-section. The FAS method is verified using discrete Monte-Carlo scattering simulations run at small timesteps to include each individual scattering event.more » We identify the FAS regime of interest as where the ratio of temporal/spatial scale-of-interest to slowing-down time/length is from 10 -3 to 0.3–0.7; the upper limit corresponds to Coulomb logarithm of 20–2, respectively. Two test problems, high-velocity interpenetrating plasma flows and keV-temperature ion equilibration, are used to highlight systems where including FAS is important to capture relevant physics.« less

Kinetic Effects in Parametric Instabilities of Finite Amplitude Alfven Waves in a Drifting Multi-Species Plasma

NASA Astrophysics Data System (ADS)

Maneva, Y. G.; Araneda, J. A.; Poedts, S.

2014-12-01

We consider parametric instabilities of finite-amplitude large-scale Alfven waves in a low-beta collisionless multi-species plasma, consisting of fluid electrons, kinetic protons and a drifting population of minor ions. Complementary to many theoretical studies, relying on fluid or multi-fluid approach, in this work we present the solutions of the parametric instability dispersion relation, including kinetic effects in the parallel direction, along the ambient magnetic field. This provides us with the opportunity to predict the importance of some wave-particle interactions like Landau damping of the daughter ion-acoustic waves for the given pump wave and plasma conditions. We apply the dispersion relation to plasma parameters, typical for low-beta collisionless solar wind close to the Sun. We compare the analytical solutions to the linear stage of hybrid numerical simulations and discuss the application of the model to the problems of preferential heating and differential acceleration of minor ions in the solar corona and the fast solar wind. The results of this study provide tools for prediction and interpretation of the magnetic field and particles data as expected from the future Solar Orbiter and Solar Probe Plus missions.

Charging and performance of the CubeSTAR satellite studied by numerical simulations

NASA Astrophysics Data System (ADS)

Miloch, Wojciech; Bekkeng, Tore André; Lindem, Torfinn

2012-07-01

A good understanding of spacecraft-plasma interaction is important for all space missions and experiments. The spacecraft potential is determined by the plasma, photoemission and other currents [1]. A charged object can significantly disturb the surrounding plasma, and lead to wake formation. The wake features, such as ion focusing, can influence the measurements of the plasma by the instruments onboard. A study of this problem using analytical models is difficult and can not account for all phenomena. This has encouraged use of numerical models for self-consistent studies of the plasma-object interactions on a detailed kinetic level [2][3]. With three-dimensional particle-in-cell (PIC) simulations [3][4], we address the spacecraft-plasma interaction in various plasma environments, and account for the self-consistent charging of the spacecraft by plasma and photoemission currents. As a specific case, we consider the interactions between plasma and a CubeSTAR satellite. CubeSTAR is a nano-satellite for the space weather studies being constructed in Norway, with the launch scheduled for year 2013. With a novel Langmuir probe system [5], it will measure the absolute electron densities with a high spatial resolution, allowing for studies of small scale plasma irregularities. We perform a systematic study of the role of the wakefield on the measurements with the Langmuir probes onboard the CubeSTAR for the plasma conditions relevant for the planned polar orbit. The simulation results are of relevance also for other spacecraft missions. [1] Whipple E C, Rep. Prog. Phys. 44, 1197 (1981). [2] Roussel J F and Berthelier J J, J. Geophys. Res. 109, A01104 (2004). [3] Yaroshenko V V et al., J. Geophys. Res. 116, A12218 (2011). [4] Miloch W J Kroll M and Block D 2010 Phys. Plasmas 17, 103703 (2010). [5] Bekkeng T A et al. Meas. Sci. Technol. 21, 085903 (2010).

Ultrafast and nanoscale diodes

NASA Astrophysics Data System (ADS)

Zhang, Peng; Lau, Y. Y.

2016-10-01

Charge carrier transport across interfaces of dissimilar materials (including vacuum) is the essence of all electronic devices. Ultrafast charge transport across a nanometre length scale is of fundamental importance in the miniaturization of vacuum and plasma electronics. With the combination of recent advances in electronics, photonics and nanotechnology, these miniature devices may integrate with solid-state platforms, achieving superior performance. This paper reviews recent modelling efforts on quantum tunnelling, ultrafast electron emission and transport, and electrical contact resistance. Unsolved problems and challenges in these areas are addressed.

Bone regeneration and stem cells

PubMed Central

Arvidson, K; Abdallah, B M; Applegate, L A; Baldini, N; Cenni, E; Gomez-Barrena, E; Granchi, D; Kassem, M; Konttinen, Y T; Mustafa, K; Pioletti, D P; Sillat, T; Finne-Wistrand, A

2011-01-01

Abstract This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet-rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed. PMID:21129153

Coronal Heating and the Need for High-Resolution Observations

NASA Technical Reports Server (NTRS)

Klimchuk, James A.

2008-01-01

Despite excellent progress in recent years in understanding coronal heating, there remain many crucial questions that are still unanswered. Limitations in the observations are one important reason. Both theoretical and observational considerations point to the importance of small spatial scales, impulsive energy release, strong dynamics, and extreme plasma nonuniformity. As a consequence, high spatial resolution, broad temperature coverage, high temperature fidelity, and sensitivity to velocities and densities are all critical observational parameters. Current instruments lack one or more of these properties, and this has led to considerable ambiguity and confusion. In this talk, I will discuss recent ideas about coronal heating and emphasize that high spatial resolution observations, especially spectroscopic observations, are needed to make major progress on this important problem.

Structure of the reconnection layer and the associated slow shocks: Two-dimensional simulations of a Riemann problem

NASA Astrophysics Data System (ADS)

Cremer, Michael; Scholer, Manfred

2000-12-01

The kinetic structure of the reconnection layer in the magnetotail is investigated by two-dimensional hybrid simulations. As a proxy, the solution of the Riemann problem of the collapse of a current sheet with a normal magnetic field component is considered for two cases of the plasma beta (particle to magnetic field pressure): β=0.02 and β=0.002. The collapse results in an expanding layer of compressed and heated plasma, which is accelerated up to the Alfvén speed vA. The boundary layer separating this hot reconnection like layer from the cold lobe plasma is characterized by a beam of back-streaming ions with a field-aligned bulk speed of ~=2vA relative to the cold lobe ion population at rest. As a consequence, obliquely propagating waves are excited via the electromagnetic ion/ion cyclotron instability, which led to perpendicular heating of the ions in the boundary layer as well as further outside the layer in the lobe. In both regions, waves are found which propagate almost parallel to the magnetic field and which are identified as Alfvén ion cyclotron (AIC) waves. These waves are excited by the temperature anisotropy instability. The temperature anisotropy increases with decreasing plasma beta. Thus the anisotropy threshold of the instability is exceeded even in the case of a rather small beta value. The AIC waves, when convected downstream of what can be defined as the the slow shock, make an important contribution to the ion thermalization process. More detailed information on the dissipation process in the slow shocks is gained by analyzing individual ion trajectories.

Boundary-value problem for plasma centrifuge at arbitrary magnetic Reynolds numbers

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.; Hong, S. H.

1977-01-01

We solve in closed form the boundary-value problem for the partial differential equations which describe the (azimuthal) rotation velocity and induced magnetic fields in a cylindrical plasma centrifuge with ring electrodes of different radii and an external, axial magnetic field. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number H and the magnetic Reynolds number R. For small Hall coefficients, the induced magnetic field does not affect the plasma rotation. As a result of the Lorentz forces, the plasma rotates with speeds as high as 100,000 cm/sec around its axis of symmetry at typical conditions, so that the lighter (heavier) ion and atom components are enriched at (off) the center of the discharge cylinder.

Multilevel Iterative Methods in Nonlinear Computational Plasma Physics

NASA Astrophysics Data System (ADS)

Knoll, D. A.; Finn, J. M.

1997-11-01

Many applications in computational plasma physics involve the implicit numerical solution of coupled systems of nonlinear partial differential equations or integro-differential equations. Such problems arise in MHD, systems of Vlasov-Fokker-Planck equations, edge plasma fluid equations. We have been developing matrix-free Newton-Krylov algorithms for such problems and have applied these algorithms to the edge plasma fluid equations [1,2] and to the Vlasov-Fokker-Planck equation [3]. Recently we have found that with increasing grid refinement, the number of Krylov iterations required per Newton iteration has grown unmanageable [4]. This has led us to the study of multigrid methods as a means of preconditioning matrix-free Newton-Krylov methods. In this poster we will give details of the general multigrid preconditioned Newton-Krylov algorithm, as well as algorithm performance details on problems of interest in the areas of magnetohydrodynamics and edge plasma physics. Work supported by US DoE 1. Knoll and McHugh, J. Comput. Phys., 116, pg. 281 (1995) 2. Knoll and McHugh, Comput. Phys. Comm., 88, pg. 141 (1995) 3. Mousseau and Knoll, J. Comput. Phys. (1997) (to appear) 4. Knoll and McHugh, SIAM J. Sci. Comput. 19, (1998) (to appear)

Minimally-Invasive Gene Transfection by Chemical and Physical Interaction of Atmospheric Pressure Plasma Flow

NASA Astrophysics Data System (ADS)

Kaneko, Toshiro

2014-10-01

Non-equilibrium atmospheric pressure plasma irradiated to the living-cell is investigated for medical applications such as gene transfection, which is expected to play an important role in molecular biology, gene therapy, and creation of induced pluripotent stem (iPS) cells. However, the conventional gene transfection using the plasma has some problems that the cell viability is low and the genes cannot be transferred into some specific lipid cells, which is attributed to the unknown mechanism of the gene transfection using the plasma. Therefore, the time-controlled atmospheric pressure plasma flow is generated and irradiated to the living-cell suspended solution for clarifying the transfection mechanism toward developing highly-efficient and minimally- invasive gene transfection system. In this experiment, fluorescent dye YOYO-1 is used as the simulated gene and LIVE/DEAD Stain is simultaneously used for cell viability assay. By the fluorescence image, the transfection efficiency is calculated as the ratio of the number of transferred and surviving cells to total cell count. It is clarified that the transfection efficiency is significantly increased by the short-time (<4 sec) and short-distance (<40 mm) plasma irradiation, and the high transfection efficiency of 53% is realized together with the high cell viability (>90%). This result indicates that the physical effects such as the electric field caused by the charged particles arriving at the surface of the cell membrane, and chemical effects associated with plasma-activated products in solution act synergistically to enhance the cell-membrane transport with low-damage. This work was supported by JSPS KAKENHI Grant Number 24108004.

On-line Model Structure Selection for Estimation of Plasma Boundary in a Tokamak

NASA Astrophysics Data System (ADS)

Škvára, Vít; Šmídl, Václav; Urban, Jakub

2015-11-01

Control of the plasma field in the tokamak requires reliable estimation of the plasma boundary. The plasma boundary is given by a complex mathematical model and the only available measurements are responses of induction coils around the plasma. For the purpose of boundary estimation the model can be reduced to simple linear regression with potentially infinitely many elements. The number of elements must be selected manually and this choice significantly influences the resulting shape. In this paper, we investigate the use of formal model structure estimation techniques for the problem. Specifically, we formulate a sparse least squares estimator using the automatic relevance principle. The resulting algorithm is a repetitive evaluation of the least squares problem which could be computed in real time. Performance of the resulting algorithm is illustrated on simulated data and evaluated with respect to a more detailed and computationally costly model FREEBIE.

Determination of highly protein bound drugs in plasma using high-performance liquid chromatography and column switching, exemplified by the retinoids.

PubMed

Wyss, R; Bucheli, F

1988-12-02

During method development for the determination of either isotretinoin, tretinoin and their 4-oxo-metabolites, or etretinate, acitretin and 13-cis-acitretin in plasma using high-performance liquid chromatography and column switching, recovery problems arose, when undiluted plasma samples were injected directly onto the precolumn. These recovery problems may be due to the strong binding of the retinoids to different plasma proteins. Measures to overcome this strong protein binding, such as variation of the injection solution composition and the purge mobile phase, were systematically investigated. Best recoveries were obtained by diluting of plasma with 9 mM sodium hydroxide-acetonitrile (8:2, v/v) and protein precipitation with ethanol for the isotretinoin and etretinate series, respectively, in combination with the use of a purge mobile phase containing ammonium acetate and 10-20% acetonitrile. Less effective was the use of a longer precolumn or heating of the precolumn.

Implementation of a hybrid particle code with a PIC description in r–z and a gridless description in ϕ into OSIRIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, A., E-mail: davidsoa@physics.ucla.edu; Tableman, A., E-mail: Tableman@physics.ucla.edu; An, W., E-mail: anweiming@ucla.edu

2015-01-15

For many plasma physics problems, three-dimensional and kinetic effects are very important. However, such simulations are very computationally intensive. Fortunately, there is a class of problems for which there is nearly azimuthal symmetry and the dominant three-dimensional physics is captured by the inclusion of only a few azimuthal harmonics. Recently, it was proposed [1] to model one such problem, laser wakefield acceleration, by expanding the fields and currents in azimuthal harmonics and truncating the expansion. The complex amplitudes of the fundamental and first harmonic for the fields were solved on an r–z grid and a procedure for calculating the complexmore » current amplitudes for each particle based on its motion in Cartesian geometry was presented using a Marder's correction to maintain the validity of Gauss's law. In this paper, we describe an implementation of this algorithm into OSIRIS using a rigorous charge conserving current deposition method to maintain the validity of Gauss's law. We show that this algorithm is a hybrid method which uses a particles-in-cell description in r–z and a gridless description in ϕ. We include the ability to keep an arbitrary number of harmonics and higher order particle shapes. Examples for laser wakefield acceleration, plasma wakefield acceleration, and beam loading are also presented and directions for future work are discussed.« less

Some experiments with the tunnel probe in a low temperature magnetized plasma

NASA Astrophysics Data System (ADS)

Kovačič, J.; Gyergyek, T.; Kavaš, B.; Vodnik, M.; Kavčič, J.; Gunn, J. P.

2018-02-01

Experiments were performed using a Tunnel Probe (TP) inside the weakly-ionised plasma of the Linear Magnetized Plasma Device (LMPD). The TP is designed as a concave probe, which should annihilate the problem of sheath expansion in the ion branch of the I-V characteristic. As the ion saturation current is consequently well defined, the ion parallel current and plasma density can be more accurately calculated. Furthermore the ratio between the ion saturation currents on the two collectors (tunnel ring and the back-plate) can be used to derive the electron temperature. The TP has been repeatedly used with success on the former Castor and Tore-Supra tokamaks and will be used on the upgraded version of Tore-supra, namely the WEST tokamak, as well [1, 2]. It was however never used successfully in a low-temperature plasma. We studied the feasibility of the TP use in a low-temperature plasma for direct measurements of plasma temperature and density. The various probe characteristic dimensions, such as the distance between the two collectors, the aperture size and the probe radius were varied to see influence of the individual probe feature. We also varied the level of magnetization of the charged particle species, the background gas pressure (which influences the electron energy distribution function), the plasma density (important for the ratio between the λ D and the ion Larmor radius). The sensitivity of the probe alignment to the magnetic field lines was also studied. We found, that the ion saturation current does not necessarily saturate and that the probe works according to expectations only in a limited amount of regimes.

Proteomic changes in plasma of broiler chickens with femoral head necrosis

USDA-ARS?s Scientific Manuscript database

Femoral head necrosis (FHN) is a skeletal problem in broiler chickens where the proximal femoral head cartilage shows susceptibility to separation from its growth plate. The FHN selected birds showed higher bodyweights and reduced plasma cholesterol. The proteomic differences in the plasma of health...

Giant plasma membrane vesicles: models for understanding membrane organization.

PubMed

Levental, Kandice R; Levental, Ilya

2015-01-01

The organization of eukaryotic membranes into functional domains continues to fascinate and puzzle cell biologists and biophysicists. The lipid raft hypothesis proposes that collective lipid interactions compartmentalize the membrane into coexisting liquid domains that are central to membrane physiology. This hypothesis has proven controversial because such structures cannot be directly visualized in live cells by light microscopy. The recent observations of liquid-liquid phase separation in biological membranes are an important validation of the raft hypothesis and enable application of the experimental toolbox of membrane physics to a biologically complex phase-separated membrane. This review addresses the role of giant plasma membrane vesicles (GPMVs) in refining the raft hypothesis and expands on the application of GPMVs as an experimental model to answer some of key outstanding problems in membrane biology. Copyright © 2015 Elsevier Inc. All rights reserved.

Understanding the Accretion Engine in Pre-main Sequence Stars

NASA Astrophysics Data System (ADS)

Gómez de Castro, Ana I.

2009-05-01

Planetary systems are angular momentum reservoirs generated during star formation as a result of the joint action of gravity and angular momentum conservation. The accretion process drives to the generation of powerful engines able to drive the optical jets and the molecular outflows. A fraction of the engine energy is released into heating the circumstellar plasma to temperatures between 3000 K to 10 MK depending on the plasma location and density. There are very important unsolved problems concerning the nature of the engine, its evolution and its impact in the chemical evolution of the disk. Of special relevance is the understanding of the shear layer between the stellar photosphere and the disk; this layer controls a significant fraction of the magnetic field building up and the subsequent dissipative processes ought to be studied in the UV.

Bringing global gyrokinetic turbulence simulations to the transport timescale using a multiscale approach

NASA Astrophysics Data System (ADS)

Parker, Jeffrey; Lodestro, Lynda; Told, Daniel; Merlo, Gabriele; Ricketson, Lee; Campos, Alejandro; Jenko, Frank; Hittinger, Jeffrey

2017-10-01

Predictive whole-device simulation models will play an increasingly important role in ensuring the success of fusion experiments and accelerating the development of fusion energy. In the core of tokamak plasmas, a separation of timescales between turbulence and transport makes a single direct simulation of both processes computationally expensive. We present the first demonstration of a multiple-timescale method coupling global gyrokinetic simulations with a transport solver to calculate the self-consistent, steady-state temperature profile. Initial results are highly encouraging, with the coupling method appearing robust to the difficult problem of turbulent fluctuations. The method holds potential for integrating first-principles turbulence simulations into whole-device models and advancing the understanding of global plasma behavior. Work supported by US DOE under Contract DE-AC52-07NA27344 and the Exascale Computing Project (17-SC-20-SC).

Foundations of High-Pressure Thermal Plasmas

NASA Astrophysics Data System (ADS)

Murphy, Anthony B.; Uhrlandt, Dirk

2018-06-01

An introduction to the main methods used to produce, model and measure thermal plasmas is provided, with emphasis on the differences between thermal plasmas and other types of processing plasmas. The critical properties of thermal plasmas are explained in physical terms and their importance in different applications is considered. The characteristics, and advantages and disadvantages, of the different main types of thermal plasmas (transferred and non-transferred arcs, radio-frequency inductively-coupled plasmas and microwave plasmas) are discussed. The methods by which flow is stabilized in arc plasmas are considered. The important concept of local thermodynamic equilibrium (LTE) is explained, leading into a discussion of the importance of thermophysical properties, and their calculation in LTE and two-temperature plasmas. The standard equations for modelling thermal plasmas are presented and contrasted with those used for non-equilibrium plasmas. Treatments of mixed-gas and non-LTE plasmas are considered, as well as the sheath regions adjacent to electrodes. Finally, the main methods used for electrical, optical, spectroscopic and laser diagnostics of thermal plasmas are briefly introduced, with an emphasis on the required assumptions for their reliable implementation, and the specific requirements of thermal plasmas.

Proteomic signatures in plasma during early acute renal allograft rejection.

PubMed

Freue, Gabriela V Cohen; Sasaki, Mayu; Meredith, Anna; Günther, Oliver P; Bergman, Axel; Takhar, Mandeep; Mui, Alice; Balshaw, Robert F; Ng, Raymond T; Opushneva, Nina; Hollander, Zsuzsanna; Li, Guiyun; Borchers, Christoph H; Wilson-McManus, Janet; McManus, Bruce M; Keown, Paul A; McMaster, W Robert

2010-09-01

Acute graft rejection is an important clinical problem in renal transplantation and an adverse predictor for long term graft survival. Plasma biomarkers may offer an important option for post-transplant monitoring and permit timely and effective therapeutic intervention to minimize graft damage. This case-control discovery study (n = 32) used isobaric tagging for relative and absolute protein quantification (iTRAQ) technology to quantitate plasma protein relative concentrations in precise cohorts of patients with and without biopsy-confirmed acute rejection (BCAR). Plasma samples were depleted of the 14 most abundant plasma proteins to enhance detection sensitivity. A total of 18 plasma proteins that encompassed processes related to inflammation, complement activation, blood coagulation, and wound repair exhibited significantly different relative concentrations between patient cohorts with and without BCAR (p value <0.05). Twelve proteins with a fold-change >or=1.15 were selected for diagnostic purposes: seven were increased (titin, lipopolysaccharide-binding protein, peptidase inhibitor 16, complement factor D, mannose-binding lectin, protein Z-dependent protease and beta(2)-microglobulin) and five were decreased (kininogen-1, afamin, serine protease inhibitor, phosphatidylcholine-sterol acyltransferase, and sex hormone-binding globulin) in patients with BCAR. The first three principal components of these proteins showed clear separation of cohorts with and without BCAR. Performance improved with the inclusion of sequential proteins, reaching a primary asymptote after the first three (titin, kininogen-1, and lipopolysaccharide-binding protein). Longitudinal monitoring over the first 3 months post-transplant based on ratios of these three proteins showed clear discrimination between the two patient cohorts at time of rejection. The score then declined to baseline following treatment and resolution of the rejection episode and remained comparable between cases and controls throughout the period of quiescent follow-up. Results were validated using ELISA where possible, and initial cross-validation estimated a sensitivity of 80% and specificity of 90% for classification of BCAR based on a four-protein ELISA classifier. This study provides evidence that protein concentrations in plasma may provide a relevant measure for the occurrence of BCAR and offers a potential tool for immunologic monitoring.

Proteomic Signatures in Plasma during Early Acute Renal Allograft Rejection*

PubMed Central

Freue, Gabriela V. Cohen; Sasaki, Mayu; Meredith, Anna; Günther, Oliver P.; Bergman, Axel; Takhar, Mandeep; Mui, Alice; Balshaw, Robert F.; Ng, Raymond T.; Opushneva, Nina; Hollander, Zsuzsanna; Li, Guiyun; Borchers, Christoph H.; Wilson-McManus, Janet; McManus, Bruce M.; Keown, Paul A.; McMaster, W. Robert

2010-01-01

Acute graft rejection is an important clinical problem in renal transplantation and an adverse predictor for long term graft survival. Plasma biomarkers may offer an important option for post-transplant monitoring and permit timely and effective therapeutic intervention to minimize graft damage. This case-control discovery study (n = 32) used isobaric tagging for relative and absolute protein quantification (iTRAQ) technology to quantitate plasma protein relative concentrations in precise cohorts of patients with and without biopsy-confirmed acute rejection (BCAR). Plasma samples were depleted of the 14 most abundant plasma proteins to enhance detection sensitivity. A total of 18 plasma proteins that encompassed processes related to inflammation, complement activation, blood coagulation, and wound repair exhibited significantly different relative concentrations between patient cohorts with and without BCAR (p value <0.05). Twelve proteins with a fold-change ≥1.15 were selected for diagnostic purposes: seven were increased (titin, lipopolysaccharide-binding protein, peptidase inhibitor 16, complement factor D, mannose-binding lectin, protein Z-dependent protease and β2-microglobulin) and five were decreased (kininogen-1, afamin, serine protease inhibitor, phosphatidylcholine-sterol acyltransferase, and sex hormone-binding globulin) in patients with BCAR. The first three principal components of these proteins showed clear separation of cohorts with and without BCAR. Performance improved with the inclusion of sequential proteins, reaching a primary asymptote after the first three (titin, kininogen-1, and lipopolysaccharide-binding protein). Longitudinal monitoring over the first 3 months post-transplant based on ratios of these three proteins showed clear discrimination between the two patient cohorts at time of rejection. The score then declined to baseline following treatment and resolution of the rejection episode and remained comparable between cases and controls throughout the period of quiescent follow-up. Results were validated using ELISA where possible, and initial cross-validation estimated a sensitivity of 80% and specificity of 90% for classification of BCAR based on a four-protein ELISA classifier. This study provides evidence that protein concentrations in plasma may provide a relevant measure for the occurrence of BCAR and offers a potential tool for immunologic monitoring. PMID:20501940

Charging of particles on a surface

NASA Astrophysics Data System (ADS)

Heijmans, Lucas; Nijdam, Sander

2016-09-01

This contribution focusses on the seemingly easy problem of the charging of micrometer sized particles on a substrate in a plasma. This seems trivial, because much is known about both the charging of surfaces near a plasma and of particles in the plasma bulk. The problem, however, becomes much more complicated when the particle is on the substrate surface. The charging currents to the particle are then highly altered by the substrate plasma sheath. Currently there is no consensus in literature about the resulting particle charge. We shall present both experimental measurements and numerical simulations of the charge on these particles. The experimental results are acquired by measuring the particle acceleration in an external electric field. For the simulations we have used our specially developed model. We shall compare these results to other estimates found in literature.

Solving free-plasma-boundary problems with the SIESTA MHD code

NASA Astrophysics Data System (ADS)

Sanchez, R.; Peraza-Rodriguez, H.; Reynolds-Barredo, J. M.; Tribaldos, V.; Geiger, J.; Hirshman, S. P.; Cianciosa, M.

2017-10-01

SIESTA is a recently developed MHD equilibrium code designed to perform fast and accurate calculations of ideal MHD equilibria for 3D magnetic configurations. It is an iterative code that uses the solution obtained by the VMEC code to provide a background coordinate system and an initial guess of the solution. The final solution that SIESTA finds can exhibit magnetic islands and stochastic regions. In its original implementation, SIESTA addressed only fixed-boundary problems. This fixed boundary condition somewhat restricts its possible applications. In this contribution we describe a recent extension of SIESTA that enables it to address free-plasma-boundary situations, opening up the possibility of investigating problems with SIESTA in which the plasma boundary is perturbed either externally or internally. As an illustration, the extended version of SIESTA is applied to a configuration of the W7-X stellarator.

Mammalian monoamine-oxidizing enzymes, with special reference to benzylamine oxidase in human tissues.

PubMed

Lewinsohn, R

1984-01-01

A review is presented of the monoamine-oxidizing enzymes with special reference to the activity of benzylamine oxidase (BzAO) in human tissues. Methods of study of amine oxidases, properties (chiefly of BzAO) and some problems concerning substrate and inhibitor specificity and multiple forms of monoamine oxidase (MAO) are surveyed. The substrate specificity of human plasma BzAO is compared with that of amine-oxidizing enzymes in plasma or serum of other species. Correlations of plasma BzAO and platelet MAO activity with clinical findings are discussed. The distribution of amine oxidase activities in solid human tissues is reviewed, in particular BzAO in blood vessels and richly-vascularized tissues, as well as kinetic constants and altered patterns of activity of BzAO in human atherosclerosis. Activities of the amine oxidases in non-vascular smooth muscle, in cultured cells, and in various tissues related to human gestation, are discussed. The present knowledge of BzAO is discussed in terms of its possible clinical relevance to several human disease states, and the importance of the enzyme in the human body.

Perpendicular dynamics of runaway electrons in tokamak plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandez-Gomez, I.; Martin-Solis, J. R.; Sanchez, R.

2012-10-15

In this paper, it will be shown that the runaway phenomenon in tokamak plasmas cannot be reduced to a one-dimensional problem, based on the competence between electric field acceleration and collisional friction losses in the parallel direction. A Langevin approach, including collisional diffusion in velocity space, will be used to analyze the two-dimensional runaway electron dynamics. An investigation of the runaway probability in velocity space will yield a criterion for runaway, which will be shown to be consistent with the results provided by the more simple test particle description of the runaway dynamics [Fuchs et al., Phys. Fluids 29, 2931more » (1986)]. Electron perpendicular collisional scattering will be found to play an important role, relaxing the conditions for runaway. Moreover, electron pitch angle scattering perpendicularly broadens the runaway distribution function, increasing the electron population in the runaway plateau region in comparison with what it should be expected from electron acceleration in the parallel direction only. The perpendicular broadening of the runaway distribution function, its dependence on the plasma parameters, and the resulting enhancement of the runaway production rate will be discussed.« less

A full-angle Monte-Carlo scattering technique including cumulative and single-event Rutherford scattering in plasmas

NASA Astrophysics Data System (ADS)

Higginson, Drew P.

2017-11-01

We describe and justify a full-angle scattering (FAS) method to faithfully reproduce the accumulated differential angular Rutherford scattering probability distribution function (pdf) of particles in a plasma. The FAS method splits the scattering events into two regions. At small angles it is described by cumulative scattering events resulting, via the central limit theorem, in a Gaussian-like pdf; at larger angles it is described by single-event scatters and retains a pdf that follows the form of the Rutherford differential cross-section. The FAS method is verified using discrete Monte-Carlo scattering simulations run at small timesteps to include each individual scattering event. We identify the FAS regime of interest as where the ratio of temporal/spatial scale-of-interest to slowing-down time/length is from 10-3 to 0.3-0.7; the upper limit corresponds to Coulomb logarithm of 20-2, respectively. Two test problems, high-velocity interpenetrating plasma flows and keV-temperature ion equilibration, are used to highlight systems where including FAS is important to capture relevant physics.

Current Collection from Space Plasmas

NASA Technical Reports Server (NTRS)

Singh, Nagendra (Editor); Wright, K. H., Jr. (Editor); Stone, Nobie H. (Editor)

1990-01-01

The First Workshop on Current Collection from Space Plasmas was held at the Tom Bevil Center on the campus of The University of Alabama in Huntsville on April 24 to 25, 1989. The intent of the workshop was to assemble experts on various topics related to the problem of current collection for deliberations that would elucidate the present understanding of the overall current collection problem. Papers presented at the workshop are presented.

Constraints on dairy cattle productivity at the smallholder level in the Philippines.

PubMed

Alejandrino, A L; Asaad, C O; Malabayabas, B; De Vera, A C; Herrera, M S; Deocaris, C C; Ignacio, L M; Palo, L P

1999-01-27

Survey data on dairy cattle production were gathered in two sites [Site I (three-year survey) and Site II (two-year survey)] in Southern Luzon, Philippines. Crossbred (Holstein-Friesian x Sahiwal) dairy cows (n = 122) managed by smallholder farmers belonging to five primary cooperatives under the federation of dairy farmers, were monitored monthly for milk production, feed intake and availability, and reproduction and health status. The purpose of the survey was to identify constraints to productivity. The reproductive status of the cows was monitored by measuring milk and plasma progesterone concentrations by radioimmunoassay and rectal palpation of the ovaries. Plasma concentrations of selected metabolites [beta-hydroxybutyrate (BHB), inorganic phosphorus, albumin, globulin, urea] were also measured at one month before calving and at one month and 2-3 months postpartum, to determine if these could serve as biochemical indicators of nutritional stress. A long calving interval (CI = > 400 days) was identified as the major constraint to productivity of dairy cattle on smallholder farms. The three main problems related to this reproductive constraint were: (1) poor breeding management, in particular lack of accurate estrus detection; (2) repeat breeding, i.e. three or more services were required before conception; and (3) poor ovarian function, shown by some cows with lose progesterone levels. An important cause of these problems was undernutrition, particularly at critical periods of the cow's reproductive life, reflected in the slow recovery from loss in body weight and condition score during the early postpartum period and the increased plasma BHB values at peripartum period in some cows, indicative of negative energy balance, and the flat lactation profile. These findings are useful and relevant as a database in the development of an appropriate management scheme aimed toward improving dairy cattle production and productivity at smallholder level. It highlights the importance of estrus detection, good breeding management and the use of a practical strategic nutritional supplementation, particularly during stressful periods in the cows's reproductive life.

Full wave description of VLF wave penetration through the ionosphere

NASA Astrophysics Data System (ADS)

Kuzichev, Ilya; Shklyar, David

2010-05-01

Of the many problems in whistler study, wave propagation through the ionosphere is among the most important, and the most difficult at the same time. Both satellite and ground-based investigations of VLF waves include considerations of this problem, and it has been in the focus of research since the beginning of whistler study (Budden [1985]; Helliwell [1965]). The difficulty in considering VLF wave passage through the ionosphere is, after all, due to fast variation of the lower ionosphere parameters as compared to typical VLF wave number. This makes irrelevant the consideration in the framework of geometrical optics, which, along with a smooth variations of parameters, is always based on a particular dispersion relation. Although the full wave analysis in the framework of cold plasma approximation does not require slow variations of plasma parameters, and does not assume any particular wave mode, the fact that the wave of a given frequency belongs to different modes in various regions makes numerical solution of the field equations not simple. More specifically, as is well known (e.g. Ginzburg and Rukhadze [1972]), in a cold magnetized plasma, there are, in general, two wave modes related to a given frequency. Both modes, however, do not necessarily correspond to propagating waves. In particular, in the frequency range related to whistler waves, the other mode is evanescent, i.e. it has a negative value of N2 (the refractive index squared). It means that one of solutions of the relevant differential equations is exponentially growing, which makes a straightforward numerical approach to these equations despairing. This well known difficulty in the problem under discussion is usually identified as numerical swamping (Budden [1985]). Resolving the problem of numerical swamping becomes, in fact, a key point in numerical study of wave passage through the ionosphere. As it is typical of work based on numerical simulations, its essential part remains virtually hidden. Then, every researcher, in order to get quantitative characteristics of the process, such as transmission and reflection coefficients, needs to go through the whole problem. That is why the number of publications dealing with VLF wave transmission through the ionosphere does not run short. In this work, we develop a new approach to the problem, such that its intrinsic difficulty is resolved analytically, while numerical calculations are reduced to stable equations solvable with the help of a routine program. Using this approach, the field of VLF wave incident on the ionosphere from above is calculated as a function of height, and reflection coefficients for different frequencies and angles of incidence are obtained. In particular, for small angles of incidence, for which incident waves reach the ground, the reflection coefficient appears to be an oscillating function of frequency. Another goal of the work is to present all equations and related formulae in an undisguised form, in order that the problem may be solved in a straightforward way, once the ionospheric plasma parameters are given. References Budden, K.G. (1985), The Propagation of Radio Waves, Cambridge Univ. Press, Cambridge, U.K. Ginzburg, V.L., and Rukhadze, A.A. (1972), Waves in Magnetoactive Plasma. In Handbuch der Physik (ed. S. Flügge). Vol. 49, Part IV, p. 395, Springer Verlag, Berlin. Helliwell, R. A. (1965), Whistlers and Related Ionospheric Phenomena, Stanford University Press, Stanford, California.

Paradigm shifts in plasma processing and application of fundamental kinetics to problems targeting 5 nm technology device technology

NASA Astrophysics Data System (ADS)

Chen, Lee

2016-09-01

It is often said that semiconductor technology is approaching the end of scaling. While fundamental device limits do approach, plasma etching has been doing the heavy lifting to supplement the basic limits in lithography. RF plasmas, pulsing in many forms, diffusion plasmas are but a few of the important developments over the last 20 years that have succeeded in the seemingly impossible tasks. The commonality of these plasmas is being self-consistent: their near-Boltzmann EEDf maintains ionization with its tail while providing charge-balance with its Te . To control the plasma chemistry is to control its EEDf; the entanglement of ionization with charge-balance in self-consistent plasmas places a constraint on the decoupling of plasma chemistry from ionization. Example like DC/RF parallel-plate hybridizes stochastic heating with DC-cathode injected e- -beam. While such arrangement offers some level of decoupling, it raised more questions than what it helped answered along the lines of beam-plasma instabilities, bounce-resonance ionization, etc. Pure e- -beam plasmas could be a drastic departure from the self-consistent plasmas. Examples like the NRL e- -beam system and the more recent TEL NEP (Nonambipolar e- Plasma) show strong decoupling of Te from ionization but it is almost certain, many more questions lurk: the functions connecting collisional relaxation with instabilities, the channels causing the dissociation of large fluorocarbons (controlling the ion-to- radical ratio), the production of the damaging deep UV in e- -beam plasmas, etc., and the list goes on. IADf is one factor on feature-profile and IEDf determines the surgical surface-excitation governing the selectivity, and both functions have Ti as the origin; what controls the e- -beam plasmas' Ti ? RF-bias has served well in applications requiring energetic excitation but, are there ways to improve the IEDf tightness? What are the adverse side-effects of ``improved IEDf''? Decades ago an infant RF-plasma was thrown into the dry-etch arena and it hit the ground running with much of the understandings as after the facts. While the etching industry enjoys the heavy lifting by the successful self-consistent plasmas, perhaps time can be used on front-loaded soul searching of the ``maybe needed'' plasmas, for the future etching needs.

Parallel heat transport in reversed shear magnetic field configurations

NASA Astrophysics Data System (ADS)

Blazevski, D.; Del-Castillo-Negrete, D.

2012-03-01

Transport in magnetized plasmas is a key problem in controlled fusion, space plasmas, and astrophysics. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), χ, and the perpendicular, χ, conductivities (χ/χ may exceed 10^10 in fusion plasmas); (ii) Magnetic field lines chaos; and (iii) Nonlocal parallel transport. We have recently developed a Lagrangian Green's function (LG) method to solve the local and non-local parallel (χ/χ->∞) transport equation applicable to integrable and chaotic magnetic fields. footnotetext D. del-Castillo-Negrete, L. Chac'on, PRL, 106, 195004 (2011); D. del-Castillo-Negrete, L. Chac'on, Phys. Plasmas, APS Invited paper, submitted (2011). The proposed method overcomes many of the difficulties faced by standard finite different methods related to the three issues mentioned above. Here we apply the LG method to study transport in reversed shear configurations. We focus on the following problems: (i) separatrix reconnection of magnetic islands and transport; (ii) robustness of shearless, q'=0, transport barriers; (iii) leaky barriers and shearless Cantori.

3-Dimensional Modeling of Capacitively and Inductively Coupled Plasma Etching Systems

NASA Astrophysics Data System (ADS)

Rauf, Shahid

2008-10-01

Low temperature plasmas are widely used for thin film etching during micro and nano-electronic device fabrication. Fluid and hybrid plasma models were developed 15-20 years ago to understand the fundamentals of these plasmas and plasma etching. These models have significantly evolved since then, and are now a major tool used for new plasma hardware design and problem resolution. Plasma etching is a complex physical phenomenon, where inter-coupled plasma, electromagnetic, fluid dynamics, and thermal effects all have a major influence. The next frontier in the evolution of fluid-based plasma models is where these models are able to self-consistently treat the inter-coupling of plasma physics with fluid dynamics, electromagnetics, heat transfer and magnetostatics. We describe one such model in this paper and illustrate its use in solving engineering problems of interest for next generation plasma etcher design. Our 3-dimensional plasma model includes the full set of Maxwell equations, transport equations for all charged and neutral species in the plasma, the Navier-Stokes equation for fluid flow, and Kirchhoff's equations for the lumped external circuit. This model also includes Monte Carlo based kinetic models for secondary electrons and stochastic heating, and can take account of plasma chemistry. This modeling formalism allows us to self-consistently treat the dynamics in commercial inductively and capacitively coupled plasma etching reactors with realistic plasma chemistries, magnetic fields, and reactor geometries. We are also able to investigate the influence of the distributed electromagnetic circuit at very high frequencies (VHF) on the plasma dynamics. The model is used to assess the impact of azimuthal asymmetries in plasma reactor design (e.g., off-center pump, 3D magnetic field, slit valve, flow restrictor) on plasma characteristics at frequencies from 2 -- 180 MHz. With Jason Kenney, Ankur Agarwal, Ajit Balakrishna, Kallol Bera, and Ken Collins.

Asymptotic-Preserving methods and multiscale models for plasma physics

NASA Astrophysics Data System (ADS)

Degond, Pierre; Deluzet, Fabrice

2017-05-01

The purpose of the present paper is to provide an overview of Asymptotic-Preserving methods for multiscale plasma simulations by addressing three singular perturbation problems. First, the quasi-neutral limit of fluid and kinetic models is investigated in the framework of non-magnetized as well as magnetized plasmas. Second, the drift limit for fluid descriptions of thermal plasmas under large magnetic fields is addressed. Finally efficient numerical resolutions of anisotropic elliptic or diffusion equations arising in magnetized plasma simulation are reviewed.

Fundamentals of Plasma Physics

NASA Astrophysics Data System (ADS)

Bellan, Paul M.

2008-07-01

Preface; 1. Basic concepts; 2. The Vlasov, two-fluid, and MHD models of plasma dynamics; 3. Motion of a single plasma particle; 4. Elementary plasma waves; 5. Streaming instabilities and the Landau problem; 6. Cold plasma waves in a magnetized plasma; 7. Waves in inhomogeneous plasmas and wave energy relations; 8. Vlasov theory of warm electrostatic waves in a magnetized plasma; 9. MHD equilibria; 10. Stability of static MHD equilibria; 11. Magnetic helicity interpreted and Woltjer-Taylor relaxation; 12. Magnetic reconnection; 13. Fokker-Planck theory of collisions; 14. Wave-particle nonlinearities; 15. Wave-wave nonlinearities; 16. Non-neutral plasmas; 17. Dusty plasmas; Appendix A. Intuitive method for vector calculus identities; Appendix B. Vector calculus in orthogonal curvilinear coordinates; Appendix C. Frequently used physical constants and formulae; Bibliography; References; Index.

Correlational approach to study interactions between dust Brownian particles in a plasma

NASA Astrophysics Data System (ADS)

Lisin, E. A.; Vaulina, O. S.; Petrov, O. F.

2018-01-01

A general approach to the correlational analysis of Brownian motion of strongly coupled particles in open dissipative systems is described. This approach can be applied to the theoretical description of various non-ideal statistically equilibrium systems (including non-Hamiltonian systems), as well as for the analysis of experimental data. In this paper, we consider an application of the correlational approach to the problem of experimental exploring the wake-mediated nonreciprocal interactions in complex plasmas. We derive simple analytic equations, which allows one to calculate the gradients of forces acting on a microparticle due to each of other particles as well as the gradients of external field, knowing only the information on time-averaged correlations of particles displacements and velocities. We show the importance of taking dissipative and random processes into account, without which consideration of a system with a nonreciprocal interparticle interaction as linearly coupled oscillators leads to significant errors in determining the characteristic frequencies in a system. In the examples of numerical simulations, we demonstrate that the proposed original approach could be an effective instrument in exploring the longitudinal wake structure of a microparticle in a plasma. Unlike the previous attempts to study the wake-mediated interactions in complex plasmas, our method does not require any external perturbations and is based on Brownian motion analysis only.

Investigation of plasma contactors for use with orbiting wires

NASA Technical Reports Server (NTRS)

Estes, Robert D.; Grossi, Mario D.; Hohlfeld, Robert

1987-01-01

The proposed Shuttle-based short tether experiments with hollow cathodes have the potential for providing important data that will not be obtained in long tether experiments. A critical property for hollow cathode effectiveness as a plasma contactor is the cross magnetic field conductivity of the emitted plasma. The different effects of hollow cathode cloud overlap in the cases of motion-driven and battery-driven operation are emphasized. The calculations presented on the size and shape of the hollow cathode cloud improve the qualitative picture of hollow cathodes in low Earth orbit and provide estimates of time constants for establishing the fully-expanded cloud. The magnetic boundary value problem calculations indicate the way in which the magnetic field will effect the shape of the cloud by resisting expansion in the direction perpendicular to the field. The large-scale interactions of the system were also considered. It was concluded that recent plasma chamber experiments by Stenzel and Urrutia do not model an electrodynamic tether well enough to apply the results to tethered system behavior. Orbiting short tether experiments on hollow cathodes will provide critical information on hollow cathode performance and the underlying physics that cannot be obtained any other way. Experiments should be conducted as soon as funding and a suitable space vehicle are available.

Studies of Plasma Flow Past Jupiters Satellite Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.

1997-01-01

We have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the interaction of Ganymede with the corotating Jovian plasma. With the successful insertion of the Galileo spacecraft into orbit around Jupiter, many new observations have been made of the Jovian magnetosphere. Some of the most exciting results thus far have been in regards to Jupiter's satellites, Io and Ganymede. In both cases the large perturbations to the background (Jovian) magnetic field have been consistent with the satellites' possession of an intrinsic magnetic field. The gravity measurements implying a differentiated core at both Io and Ganymede makes internal generation of a magnetic field by dynamo action in these satellites plausible, and, in the case of Ganymede, the identification of an intrinsic field is apparently unambiguous. For Io the situation is less clear, and further analysis is necessary to answer this important question. During the past year, we have used time-dependent three-dimensional magnetohydrodynamic (MHD) simulations to study these plasma-moon interactions. The results from these simulations have been used directly in the analysis of the Galileo magnetometer data. Our primary emphasis has been on the Io interaction, but we recently presented results on the Ganymede interaction as well. In this progress summary we describe our efforts on these problems to date.

Analytic calculation of radio emission from parametrized extensive air showers: A tool to extract shower parameters

NASA Astrophysics Data System (ADS)

Scholten, O.; Trinh, T. N. G.; de Vries, K. D.; Hare, B. M.

2018-01-01

The radio intensity and polarization footprint of a cosmic-ray induced extensive air shower is determined by the time-dependent structure of the current distribution residing in the plasma cloud at the shower front. In turn, the time dependence of the integrated charge-current distribution in the plasma cloud, the longitudinal shower structure, is determined by interesting physics which one would like to extract, such as the location and multiplicity of the primary cosmic-ray collision or the values of electric fields in the atmosphere during thunderstorms. To extract the structure of a shower from its footprint requires solving a complicated inverse problem. For this purpose we have developed a code that semianalytically calculates the radio footprint of an extensive air shower given an arbitrary longitudinal structure. This code can be used in an optimization procedure to extract the optimal longitudinal shower structure given a radio footprint. On the basis of air-shower universality we propose a simple parametrization of the structure of the plasma cloud. This parametrization is based on the results of Monte Carlo shower simulations. Deriving the parametrization also teaches which aspects of the plasma cloud are important for understanding the features seen in the radio-emission footprint. The calculated radio footprints are compared with microscopic CoREAS simulations.

Prednisolone-induced predisposition to femoral head separation and the accompanying plasma protein changes in chickens

USDA-ARS?s Scientific Manuscript database

Femoral head separation (FHS) is an idiopathic bone problem that causes lameness and production losses in commercial poultry. In a model of prednisolone induced susceptibility to FHS, the changes in plasma proteins and peptides were analyzed to find possible biomarkers. Plasma from control and FHS-s...

Particle Energization throughout the Heliosphere: Opportunities with IMAP

NASA Astrophysics Data System (ADS)

Zank, Gary

2016-04-01

Understanding the radiation environment at the Earth and beyond is one of the critical elements in our developing Space Weather capabilities and strategy. Furthermore, the energization of charged particles in a collisionless plasma remains one of the compelling unsolved yet universal problems in space physics and astrophysics. The proposed instrumentation of IMAP enables two critical goals: 1) real-time monitoring of the radiation and plasma environment as part of a Space Weather capability, and 2) making coordinated simultaneous measurements of all the basic plasma parameters needed to develop a comprehensive and detailed understanding of fundamental particle energization processes. Since the session addresses the "Physics of particle acceleration", we will survey briefly the critical open problems associated with particle acceleration during quiet and active solar wind periods. At least three elements will be discussed. 1) Dissipative processes in the quiet solar wind and at shock waves. For the former, we discuss emerging ideas about the dissipation of turbulence via structures such as flux ropes and their role in possibly energizing charged particles during quiet times, especially in the vicinity of the heliospheric current sheet. In the latter, reflected ions play an essential role in dissipative processes at both quasi-perpendicular and quasi-parallel shocks. This in turn has consequences for the energization of particles, the generation of turbulence upstream and downstream of the shock, and the importance of a pre-existing suprathermal ion population. 2) What is the role of pre-existing energetic particles versus injection from a background thermal population of charged particles in the context of diffusive shock acceleration? Does the pre-existing suprathermal particle population play a fundamental role in the dissipation processes governing heliospheric shock, as suggested by the case of the heliospheric termination shock and pickup ions? 3) What is the primary acceleration mechanism for electrons in the solar wind during both quiet and active solar wind periods? Apparently stable energetic electron power law distributions are observed for quiet periods. Does the observed kappa distribution function for electrons and the electron heat flux play an important role in generating energetic particle distributions during quiet times? The observed characteristics of energetic electrons in the vicinity of interplanetary shocks are frequently quite different from those predicted from classical diffusive shock acceleration. Is another mechanism at work? IMAPs ability to simultaneously measure energetic particles from energies as low as ~2 keV, pickup ions, the interplanetary magnetic field, and thermal plasma distributions will provide important constraints on theory and modeling of particle energization throughout the heliosphere.

Mutual information optimization for mass spectra data alignment.

PubMed

Zoppis, Italo; Gianazza, Erica; Borsani, Massimiliano; Chinello, Clizia; Mainini, Veronica; Galbusera, Carmen; Ferrarese, Carlo; Galimberti, Gloria; Sorbi, Sandro; Borroni, Barbara; Magni, Fulvio; Antoniotti, Marco; Mauri, Giancarlo

2012-01-01

"Signal" alignments play critical roles in many clinical setting. This is the case of mass spectrometry data, an important component of many types of proteomic analysis. A central problem occurs when one needs to integrate (mass spectrometry) data produced by different sources, e.g., different equipment and/or laboratories. In these cases some form of "data integration'" or "data fusion'" may be necessary in order to discard some source specific aspects and improve the ability to perform a classification task such as inferring the "disease classes'" of patients. The need for new high performance data alignments methods is therefore particularly important in these contexts. In this paper we propose an approach based both on an information theory perspective, generally used in a feature construction problem, and on the application of a mathematical programming task (i.e. the weighted bipartite matching problem). We present the results of a competitive analysis of our method against other approaches. The analysis was conducted on data from plasma/ethylenediaminetetraacetic acid (EDTA) of "control" and Alzheimer patients collected from three different hospitals. The results point to a significant performance advantage of our method with respect to the competing ones tested.

Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramos, J. J.; White, R. L.

The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-invariant solution for any initial-value problem. Examples are then given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.

Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism

DOE PAGES

Ramos, J. J.; White, R. L.

2018-03-01

The classic problem of the dynamic evolution and Landau damping of linear Langmuir electron waves in a collisionless plasma with Maxwellian background is cast as a second-order, self-adjoint problem with a continuum spectrum of real and positive squared frequencies. The corresponding complete basis of singular normal modes is obtained, along with their orthogonality relation. This yields easily the general expression of the time-reversal-invariant solution for any initial-value problem. Examples are then given for specific initial conditions that illustrate different behaviors of the Landau-damped macroscopic moments of the perturbations.

Meshless method for solving fixed boundary problem of plasma equilibrium

NASA Astrophysics Data System (ADS)

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

2015-07-01

This study solves the Grad-Shafranov equation with a fixed plasma boundary by utilizing a meshless method for the first time. Previous studies have utilized a finite element method (FEM) to solve an equilibrium inside the fixed separatrix. In order to avoid difficulties of FEM (such as mesh problem, difficulty of coding, expensive calculation cost), this study focuses on the meshless methods, especially RBF-MFS and KANSA's method to solve the fixed boundary problem. The results showed that CPU time of the meshless methods was ten to one hundred times shorter than that of FEM to obtain the same accuracy.

BOOK REVIEW: Controlled Fusion and Plasma Physics

NASA Astrophysics Data System (ADS)

Engelmann, F.

2007-07-01

This new book by Kenro Miyamoto provides an up-to-date overview of the status of fusion research and the important parts of the underlying plasma physics at a moment where, due to the start of ITER construction, an important step in fusion research has been made and many new research workers will enter the field. For them, and also for interested graduate students and physicists in other fields, the book provides a good introduction into fusion physics as, on the whole, the presentation of the material is quite appropriate for getting acquainted with the field on the basis of just general knowledge in physics. There is overlap with Miyamoto's earlier book Plasma Physics for Nuclear Fusion (MIT Press, Cambridge, USA, 1989) but only in a few sections on subjects which have not evolved since. The presentation is subdivided into two parts of about equal length. The first part, following a concise survey of the physics basis of thermonuclear fusion and of plasmas in general, covers the various magnetic configurations studied for plasma confinement (tokamak; reversed field pinch; stellarator; mirror-type geometries) and introduces the specific properties of plasmas in these devices. Plasma confinement in tokamaks is treated in particular detail, in compliance with the importance of this field in fusion research. This includes a review of the ITER concept and of the rationale for the choice of ITER's parameters. In the second part, selected topics in fusion plasma physics (macroscopic instabilities; propagation of waves; kinetic effects such as energy transfer between waves and particles including microscopic instabilities as well as plasma heating and current drive; transport phenomena induced by turbulence) are presented systematically. While the emphasis is on displaying the essential physics, deeper theoretical analysis is also provided here. Every chapter is complemented by a few related problems, but only partial hints for their solution are given. A selection of references, mostly to articles covering original research, allows the interested reader to go deeper into the various subjects. There are a few quite relevant areas which are essentially not covered in the book (plasma diagnostics; fuelling). The discussion of particle and power exhaust is limited to tokamaks and is somewhat scarce. Other points which I did not find fully satisfactory are: the index is too selective and does not really allow easy access to any specific subject. Cross references between different sections treating related topics are not always given. There are quite a lot of typographical errors which as far as cross references are concerned may be disturbing. A list of the symbols used would be a helpful supplement, especially since some of them appear with different meanings. There are apparent imperfections in the structure of certain chapters. While the English is sometimes unusual, this generally does not affect the readability. Overall, the book can be warmly recommended to all interested in familiarizing themselves with the physics of magnetic fusion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yanagawa, T.; Sakagami, H.; Nagatomo, H.

In inertial confinement fusion, the implosion process is important in forming a high-density plasma core. In the case of a fast ignition scheme using a cone-guided target, the fuel target is imploded with a cone inserted. This scheme is advantageous for efficiently heating the imploded fuel core; however, asymmetric implosion is essentially inevitable. Moreover, the effect of cone position and opening angle on implosion also becomes critical. Focusing on these problems, the effect of the asymmetric implosion, the initial position, and the opening angle on the compression rate of the fuel is investigated using a three-dimensional pure hydrodynamic code.

Finite-volume scheme for anisotropic diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Es, Bram van, E-mail: bramiozo@gmail.com; FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands"1; Koren, Barry

In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

NASA Technical Reports Server (NTRS)

Hong, S. H.; Wilhelm, H. E.

1978-01-01

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

REVIEWS OF TOPICAL PROBLEMS: Instabilities of a multicomponent plasma with accelerated particles and magnetic field generation in astrophysical objects

NASA Astrophysics Data System (ADS)

Bykov, Andrei M.; Toptygin, Igor'N.

2007-02-01

A system of MHD equations for the description of a magnetized nonequilibrium astrophysical plasma with neutral atoms and suprathermal (in particular, relativistic) particles is formulated. The instabilities of such a plasma, which arise from the presence of neutral and relativistic components, are considered. It is shown that the presence of nonthermal particles interacting with the thermal plasma component via regular and fluctuating electromagnetic fields is responsible for the emergence of specific mechanisms of MHD wave generation. The main generation mechanisms of static and turbulent magnetic fields near shock wave fronts in the Galaxy and interplanetary space are analyzed. We discuss the application of the generation effects of long-wave magnetic fluctuations to the problems of magnetic field origin and relativistic particle acceleration in astrophysical objects of various natures.

Simulation of RF-fields in a fusion device

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Witte, Dieter; Bogaert, Ignace; De Zutter, Daniel

2009-11-26

In this paper the problem of scattering off a fusion plasma is approached from the point of view of integral equations. Using the volume equivalence principle an integral equation is derived which describes the electromagnetic fields in a plasma. The equation is discretized with MoM using conforming basis functions. This reduces the problem to solving a dense matrix equation. This can be done iteratively. Each iteration can be sped up using FFTs.

Comparative analysis of polychlorinated biphenyl decomposition processes in air or argon (+oxygen) thermal plasma.

PubMed

Kostic, Z G; Stefanovic, P L; Pavlović, P B

2000-07-10

Thermal plasmas may solve one of the biggest toxic waste disposal problems. The disposal of polychlorinated biphenyls (PCBs) is a long standing problem which will get worse in the coming years, when 180000 tons of PCB-containing wastes are expected to accumulate in Europe (Hot ions break down toxic chemicals, New Scientist, 16 April 1987, p. 24.). The combustion of PCBs in ordinary incinerators (at temperature T approximately 1100 K, as measured near the inner wall of the combustion chamber (European Parliament and Council Directive on Incineration of Waste (COM/99/330), Europe energy, 543, Sept. 17, 1999, 1-23.)) can cause more problems than it solves, because highly toxic dioxins and dibenzofurans are formed if the combustion temperature is too low (T<1400 K). The paper presents a thermodynamic consideration and comparative analysis of PCB decomposition processes in air or argon (+oxygen) thermal plasmas.

On the Geometrical Optics Approach in the Theory of Freely-Localized Microwave Gas Breakdown

NASA Astrophysics Data System (ADS)

Shapiro, Michael; Schaub, Samuel; Hummelt, Jason; Temkin, Richard; Semenov, Vladimir

2015-11-01

Large filamentary arrays of high pressure gas microwave breakdown have been experimentally studied at MIT using a 110 GHz, 1.5 MW pulsed gyrotron. The experiments have been modeled by other groups using numerical codes. The plasma density distribution in the filaments can be as well analytically calculated using the geometrical optics approach neglecting plasma diffusion. The field outside the filament is a solution of an inverse electromagnetic problem. The solutions are found for the cylindrical and spherical filaments and for the multi-layered planar filaments with a finite plasma density at the boundaries. We present new results of this theory showing a variety of filaments with complex shapes. The solutions for plasma density distribution are found with a zero plasma density at the boundary of the filament. Therefore, to solve the inverse problem within the geometrical optics approximation, it can be assumed that there is no reflection from the filament. The results of this research are useful for modeling future MIT experiments.

TOPLHA and ALOHA: comparison between Lower Hybrid wave coupling codes

NASA Astrophysics Data System (ADS)

Meneghini, Orso; Hillairet, J.; Goniche, M.; Bilato, R.; Voyer, D.; Parker, R.

2008-11-01

TOPLHA and ALOHA are wave coupling simulation tools for LH antennas. Both codes are able to account for realistic 3D antenna geometries and use a 1D plasma model. In the framework of a collaboration between MIT and CEA laboratories, the two codes have been extensively compared. In TOPLHA the EM problem is self consistently formulated by means of a set of multiple coupled integral equations having as domain the triangles of the meshed antenna surface. TOPLHA currently uses the FELHS code for modeling the plasma response. ALOHA instead uses a mode matching approach and its own plasma model. Comparisons have been done for several plasma scenarios on different antenna designs: an array of independent waveguides, a multi-junction antenna and a passive/active multi-junction antenna. When simulating the same geometry and plasma conditions the two codes compare remarkably well both for the reflection coefficients and for the launched spectra. The different approach of the two codes to solve the same problem strengthens the confidence in the final results.

DOE Office of Scientific and Technical Information (OSTI.GOV)

HERRON, ISOM H

Executive summary Two important general problems of interest in plasma physics that may be addressed successfully by Magnetohydrodynamics (MHD) are: (1) Find magnetic field configurations capable of confining a plasma in equilibrium. (2) Study the stability properties of each such an equilibrium. It is often found that the length scale of many instabilities and waves that are able to grow or propagate in a system, are comparable with plasma size, such as in magnetically confined thermonuclear plasmas or in astrophysical accretion disks. Thus MHD is able to provide a good description of such large-scale disturbances. The Magnetorotational instability (MRI) ismore » one particular instance of a potential instability. The project involved theoretical work on fundamental aspects of plasma physics. Researchers at the Princeton Plasma Physics Laboratory (PPPL) began to perform a series of liquid metal Couette flow experiments between rotating cylinders. Their purpose was to produce MRI, which they had predicted theoretically 2002, but was only observed in the laboratory since this project began. The personnel on the project consisted of three persons: (1) The PI, who was partially supported on the budget during each of four summers 2005-2008. (2) Two graduate research assistants, who worked consecutively on the project throughout the years 2005-2009. As a result, the first student, Fritzner Soliman, obtained an M.S. degree in 2006; the second student, Pablo Suarez obtained the Ph.D. degree in 2009. The work was in collaboration with scientists in Princeton, periodic trips were made by the PI as part of the project. There were 4 peer-reviewed publications and one book produced.« less

Optics design for J-TEXT ECE imaging with field curvature adjustment lens.

PubMed

Zhu, Y; Zhao, Z; Liu, W D; Xie, J; Hu, X; Muscatello, C M; Domier, C W; Luhmann, N C; Chen, M; Ren, X; Tobias, B J; Zhuang, G; Yang, Z

2014-11-01

Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas. Of particular importance has been microwave electron cyclotron emission imaging (ECEI) for imaging Te fluctuations. Key to the success of ECEI is a large Gaussian optics system constituting a major portion of the focusing of the microwave radiation from the plasma to the detector array. Both the spatial resolution and observation range are dependent upon the imaging optics system performance. In particular, it is critical that the field curvature on the image plane is reduced to decrease crosstalk between vertical channels. The receiver optics systems for two ECEI on the J-TEXT device have been designed to ameliorate these problems and provide good performance with additional field curvature adjustment lenses with a meniscus shape to correct the aberrations from several spherical surfaces.

Pb and Sr isotope measurements by inductively coupled plasma mass spectrometer: efficient time management for precision improvement

NASA Astrophysics Data System (ADS)

Monna, F.; Loizeau, J.-L.; Thomas, B. A.; Guéguen, C.; Favarger, P.-Y.

1998-08-01

One of the factors limiting the precision of inductively coupled plasma mass spectrometry is the counting statistics, which depend upon acquisition time and ion fluxes. In the present study, the precision of the isotopic measurements of Pb and Sr is examined. The time of measurement is optimally shared for each isotope, using a mathematical simulation, to provide the lowest theoretical analytical error. Different algorithms of mass bias correction are also taken into account and evaluated in term of improvement of overall precision. Several experiments allow a comparison of real conditions with theory. The present method significantly improves the precision, regardless of the instrument used. However, this benefit is more important for equipment which originally yields a precision close to that predicted by counting statistics. Additionally, the procedure is flexible enough to be easily adapted to other problems, such as isotopic dilution.

Effects of Plasma Lipids and Statins on Cognitive Function.

PubMed

Li, Rui; Wang, Tian-Jun; Lyu, Pei-Yuan; Liu, Yang; Chen, Wei-Hong; Fan, Ming-Yue; Xu, Jing

2018-02-20

Dementia is the fourth most common cause of death in developed countries. The relationship between plasma lipids and cognitive function is complex and controversial. Due to the increasing life expectancy of the population, there is an urgent need to control vascular risk factors and to identify therapies to prevent and treat both cognitive impairment and dementia. Here, we reviewed the effects of plasma lipids and statins on cognitive function. We searched the PubMed database for research articles published through November 2017 with key words including "plasma lipids," "hyperlipidemia," "hypercholesterolemia," "statins," and "cognition function." Articles were retrieved and reviewed to analyze the effects of plasma lipids and statins on cognitive function and the mechanisms underlying these effects. Many studies have examined the relationship between plasma lipids and cognitive function, but no definitive conclusions can be drawn. The mechanisms involved may include blood-brain barrier injury, the influence on small blood vessels in the brain, the influence on amyloid deposition, and a neuroprotective effect. To date, most studies of statins and cognition have been observational, with few randomized controlled trials. Therefore, firm conclusions regarding whether mid- or long-term statin use affects cognition function and dementia remain elusive. However, increasing concern exists that statins may be a causative factor for cognitive problems. These adverse effects appear to be rare and likely represent a yet-to-be-defined vulnerability in susceptible individuals. The association between plasma lipids and cognition, the mechanism of the influence of plasma lipids on cognitive function, and the association between statins and cognitive function are complex issues and currently not fully understood. Future research aimed at identifying the mechanisms that underlie the effects of plasma lipids and statins on cognition will not only provide important insight into the causes and interdependencies of cognitive impairment and dementia, but also inspire novel strategies for treating and preventing these cognitive disorders.

A fluid model simulation of a simplified plasma limiter based on spectral-element time-domain method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Cheng; Ding, Dazhi, E-mail: dzding@njust.edu.cn; Fan, Zhenhong

2015-03-15

A simplified plasma limiter prototype is proposed and the fluid model coupled with Maxwell's equations is established to describe the operating mechanism of plasma limiter. A three-dimensional (3-D) simplified sandwich structure plasma limiter model is analyzed with the spectral-element time-domain (SETD) method. The field breakdown threshold of air and argon at different frequency is predicted and compared with the experimental data and there is a good agreement between them for gas microwave breakdown discharge problems. Numerical results demonstrate that the two-layer plasma limiter (plasma-slab-plasma) has better protective characteristics than a one-layer plasma limiter (slab-plasma-slab) with the same length of gasmore » chamber.« less

Working Group 5: Measurements technology and active experiments

NASA Technical Reports Server (NTRS)

Whipple, E.; Barfield, J. N.; Faelthammar, C.-G.; Feynman, J.; Quinn, J. N.; Roberts, W.; Stone, N.; Taylor, W. L.

1986-01-01

Technology issues identified by working groups 5 are listed. (1) New instruments are needed to upgrade the ability to measure plasma properties in space. (2) Facilities should be developed for conducting a broad range of plasma experiments in space. (3) The ability to predict plasma weather within magnetospheres should be improved and a capability to modify plasma weather developed. (4) Methods of control of plasma spacecraft and spacecraft plasma interference should be upgraded. (5) The space station laboratory facilities should be designed with attention to problems of flexibility to allow for future growth. These issues are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dong-Hwan; Hong, Suk-Ho; National Fusion Research Institute

Plasma characteristics in the far scrape-off layer region of tokamak play a crucial role in the stable plasma operation and its sustainability. Due to the huge facility, electrical diagnostic systems to measure plasma properties have extremely long cable length resulting in large stray current. To overcome this problem, a sideband harmonic method was applied to the Korea Superconducting Tokamak Advanced Research tokamak plasma. The sideband method allows the measurement of the electron temperature and the plasma density without the effect of the stray current. The measured plasma densities are compared with those from the interferometer, and the results show reliabilitymore » of the method.« less

Research briefing on contemporary problems in plasma science

NASA Technical Reports Server (NTRS)

1991-01-01

An overview is presented of the broad perspective of all plasma science. Detailed discussions are given of scientific opportunities in various subdisciplines of plasma science. The first subdiscipline to be discussed is the area where the contemporary applications of plasma science are the most widespread, low temperature plasma science. Opportunities for new research and technology development that have emerged as byproducts of research in magnetic and inertial fusion are then highlighted. Then follows a discussion of new opportunities in ultrafast plasma science opened up by recent developments in laser and particle beam technology. Next, research that uses smaller scale facilities is discussed, first discussing non-neutral plasmas, and then the area of basic plasma experiments. Discussions of analytic theory and computational plasma physics and of space and astrophysical plasma physics are then presented.

The major protein of bovine seminal plasma, PDC-109, is a molecular chaperone.

PubMed

Sankhala, Rajeshwer Singh; Swamy, Musti J

2010-05-11

The major protein of bovine seminal plasma, PDC-109, binds to choline phospholipids on the sperm plasma membrane and induces the efflux of cholesterol and choline phospholipids, which is an important step in sperm capacitation. The high abundance, polydisperse nature and reversibility of thermal unfolding of PDC-109 suggest significant similarities to chaperone-like proteins such as spectrin, alpha-crystallin, and alpha-synuclein. In the present study, biochemical and biophysical approaches were employed to investigate the chaperone-like activity of PDC-109. The effect of various stress factors such as high temperature, chemical denaturant (urea), and acidic pH on target proteins such as lactate dehydrogenase, alcohol dehydrogenase, and insulin were studied in both the presence and absence of PDC-109. The results obtained indicate that PDC-109 exhibits chaperone-like activity, as evidenced by its ability to suppress the nonspecific aggregation of target proteins and direct them into productive folding. Atomic force microscopic studies demonstrate that PDC-109 effectively prevents the fibrillation of insulin, which is of considerable significance since amyloidogenesis has been reported to be a serious problem during sperm maturation in certain species. Binding of phosphorylcholine or high ionic strength in the medium inhibited the chaperone-like activity of PDC-109, suggesting that most likely the aggregation state of the protein is important for the chaperone function. These observations show that PDC-109 functions as a molecular chaperone in vitro, suggesting that it may assist the proper folding of proteins involved in the bovine sperm capacitation pathway. To the best of our knowledge, this is the first study reporting chaperone-like activity of a seminal plasma protein.

Resonant interaction of electromagnetic wave with plasma layer and overcoming the radiocommunication blackout problem

NASA Astrophysics Data System (ADS)

Bogatskaya, A. V.; Klenov, N. V.; Tereshonok, M. V.; Adjemov, S. S.; Popov, A. M.

2018-05-01

We present an analysis of the possibility of penetrating electromagnetic waves through opaque media using an optical-mechanical analogy. As an example, we consider the plasma sheath surrounding the vehicle as a potential barrier and analyze the overcoming of radiocommunication blackout problem. The idea is to embed a «resonator» between the surface on the vehicle and plasma sheath which is supposed to provide an effective tunneling of the signal to the receiving antenna. We discuss the peculiarities of optical mechanical analogy applicability and analyze the radio frequency wave tunneling regime in detail. The cases of normal and oblique incidence of radiofrequency waves on the vehicle surface are studied.

Center for Extended Magnetohydrodynamics Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramos, Jesus

This researcher participated in the DOE-funded Center for Extended Magnetohydrodynamics Modeling (CEMM), a multi-institutional collaboration led by the Princeton Plasma Physics Laboratory with Dr. Stephen Jardin as the overall Principal Investigator. This project developed advanced simulation tools to study the non-linear macroscopic dynamics of magnetically confined plasmas. The collaborative effort focused on the development of two large numerical simulation codes, M3D-C1 and NIMROD, and their application to a wide variety of problems. Dr. Ramos was responsible for theoretical aspects of the project, deriving consistent sets of model equations applicable to weakly collisional plasmas and devising test problems for verification ofmore » the numerical codes. This activity was funded for twelve years.« less

Generation of quasi-perpendicular Collisionless Shocks by Laser-Produced Plasma to simulate the effects of super-compression of the Earth’s magnetosphere

NASA Astrophysics Data System (ADS)

Zakharov, Yu P.; Ponomarenko, A. G.; Terekhin, V. A.; Golubev, A. I.; Antonov, V. M.; Boyarintsev, E. L.; Vchivkov, K. V.; Melekhov, A. V.; Posukh, V. G.; Prokopov, P. A.

2017-11-01

Giant plasma releases of so called Coronal Mass Ejections (CME, with kinetic energy up to Ek ∼ 1036 эрг) from the surface of the Sun and their potential catastrophical impact onto Earth’s magnetosphere, with the probable opportunity to compress it in 2, 3 or more times [1, 2], represent one of the most important problem in the geophysical and historical bio-evolutional investigations of the past and present of the Earth. It was supposed that the re-connection of dipole magnetic field at magnetopause could play [2] an exclusive role in its inward shift, but from the more general point of view (to perform laboratory simulation [3-6] of magnetopause dynamics), a more important and common features of CME propagation in Solar Wind plasma are the formation of collisionless Quasi-Perpendicular Shocks (Q-PS) ahead of Super-Alfvenic CME. It is provided by the almost radial (along to R) motion of CME from the Sun, while the Interplanetary Magnetic Field B0 has an angle θ ∼ 45° (relative to R) near the Earth orbit. Up to date, in spite of intensive development of laser energetics and energy of Laser-produced Plasma (LP), such Q-PS never were generated by LP [7], excluding recent experiment [8] at KI-1 facility of ILP. In the given work, a first results of our study were presented together with relevant calculations by hybrid code and the basic physics of VNIIEF-model [9] for the collisionless Magnetic Laminar Mechanism (MLM) of interaction between a spherical LP and magnetized Background Plasma (BP). A special analysis was done on the conditions and data of the formation of whistler precursor in front of revealed oblique (Q-PS) shocks as well as on the first data of dipole's field compression by BP and Shocks.

Comparison of a 3-D GPU-Assisted Maxwell Code and Ray Tracing for Reflectometry on ITER

NASA Astrophysics Data System (ADS)

Gady, Sarah; Kubota, Shigeyuki; Johnson, Irena

2015-11-01

Electromagnetic wave propagation and scattering in magnetized plasmas are important diagnostics for high temperature plasmas. 1-D and 2-D full-wave codes are standard tools for measurements of the electron density profile and fluctuations; however, ray tracing results have shown that beam propagation in tokamak plasmas is inherently a 3-D problem. The GPU-Assisted Maxwell Code utilizes the FDTD (Finite-Difference Time-Domain) method for solving the Maxwell equations with the cold plasma approximation in a 3-D geometry. Parallel processing with GPGPU (General-Purpose computing on Graphics Processing Units) is used to accelerate the computation. Previously, we reported on initial comparisons of the code results to 1-D numerical and analytical solutions, where the size of the computational grid was limited by the on-board memory of the GPU. In the current study, this limitation is overcome by using domain decomposition and an additional GPU. As a practical application, this code is used to study the current design of the ITER Low Field Side Reflectometer (LSFR) for the Equatorial Port Plug 11 (EPP11). A detailed examination of Gaussian beam propagation in the ITER edge plasma will be presented, as well as comparisons with ray tracing. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466 and DE-FG02-99-ER54527.

Sensitivity of wave propagation in the LHRF to initial poloidal position in finite-aspect-ratio toroidal plasmas

NASA Astrophysics Data System (ADS)

Larson, J. J.; Pinsker, R. I.; Bonoli, P. T.; Porkolab, M.

2017-10-01

The important effect of varying the initial poloidal wave-launching location to the core accessibility of lower hybrid slow waves in a torus of finite aspect ratio has been understood for many years. Since the qualitative properties of the wave propagation of the other branch in this regime, known as the `whistler', `helicon' or simply the `fast wave', are similar in some ways to those of the slow wave, we expect a dependence on launch position for this wave also. We study this problem for both slow and fast waves, first with simplified analytic models and then using the ray-tracing code GENRAY for realistic plasma equilibria. We assess the prospects of inside, top, bottom or conventional outside launch of waves on each of the two branches. Although the slow wave has been the focus of research for LHRF heating and current drive in the past, the fast wave will play a major role in burning plasmas beyond ITER where Te(0) = 10-20 keV. The stronger electron Landau damping of the slow wave will restrict the power deposition to the outer third of the plasma, while the fast wave's weaker damping allows the wave to penetrate to the hot plasma core before depositing its power. Work supported in part by US DoE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698 and DE-FG02-91-ER54109.

Extending fullwave core ICRF simulation to SOL and antenna regions using FEM solver

NASA Astrophysics Data System (ADS)

Shiraiwa, S.; Wright, J. C.

2016-10-01

A full wave simulation approach to solve a driven RF waves problem including hot core, SOL plasmas and possibly antenna is presented. This approach allows for exploiting advantages of two different way of representing wave field, namely treating spatially dispersive hot conductivity in a spectral solver and handling complicated geometry in SOL/antenna region using an unstructured mesh. Here, we compute a mode set in each region with the RF electric field excitation on the connecting boundary between core and edge regions. A mode corresponding to antenna excitation is also computed. By requiring the continuity of tangential RF electric and magnetic fields, the solution is obtained as unique superposition of these modes. In this work, TORIC core spectral solver is modified to allow for mode excitation, and the edge region of diverted Alcator C-Mod plasma is modeled using COMSOL FEM package. The reconstructed RF field is similar in the core region to TORIC stand-alone simulation. However, it contains higher poloidal modes near the edge and captures a wave bounced and propagating in the poloidal direction near the vacuum-plasma boundary. These features could play an important role when the single power pass absorption is modest. This new capability will enable antenna coupling calculations with a realistic load plasma, including collisional damping in realistic SOL plasma and other loss mechanisms such as RF sheath rectification. USDoE Awards DE-FC02-99ER54512, DE-FC02-01ER54648.

Higher plasma orexin a levels in children with Prader-Willi syndrome compared with healthy unrelated sibling controls.

PubMed

Manzardo, Ann M; Johnson, Lisa; Miller, Jennifer L; Driscoll, Daniel J; Butler, Merlin G

2016-09-01

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder associated with maladaptive social behavior, hyperphagia and morbid obesity. Orexin A is a hypothalamic neuropeptide important as a homeostatic regulator of feeding behavior and in energy metabolism through actions in the lateral hypothalamus. Dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia seen in PWS and we sought to assess orexin A levels in PWS relative to controls children. Morning fasting plasma orexin A levels were analyzed in 23 children (aged 5-11 years) with genetically confirmed PWS and 18 age and gender matched healthy unrelated siblings without PWS. Multiplex immune assays utilized the Milliplex Human Neuropeptide Magnetic panel and the Luminex platform. Natural log-transformed orexin A data were analyzed using general linear model adjusting for diagnosis, gender, age, total body fat, and body mass index (BMI). Plasma orexin A levels were significantly higher (P < 0.006) in children with PWS (average ±SD = 1,028 pg/ml ± 358) compared with unrelated siblings (average ±SD = 609 pg/ml ± 351; P < 0.001). Orexin A levels correlated with age in females and were significantly elevated in PWS even after these effects were controlled. These findings support the hypothesis that dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia in PWS. Further studies are warranted to better understand the complex relationship between orexin A levels and the problematic behaviors consistently found in individuals with PWS. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Higher plasma orexin A levels in children with Prader-Willi syndrome compared with healthy unrelated sibling controls.

PubMed

Manzardo, Ann M; Johnson, Lisa; Miller, Jennifer L; Driscoll, Daniel J; Butler, Merlin G

2016-08-01

Prader-Willi syndrome (PWS) is a rare genetic neurodevelopmental disorder associated with maladaptive social behavior, hyperphagia, and morbid obesity. Orexin A is a hypothalamic neuropeptide important as a homeostatic regulator of feeding behavior and in energy metabolism through actions in the lateral hypothalamus. Dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia seen in PWS and we sought to assess orexin A levels in PWS relative to controls children. Morning fasting plasma orexin A levels were analyzed in 23 children (aged 5-11 years) with genetically confirmed PWS and 18 age and gender matched healthy unrelated siblings without PWS. Multiplex immune assays utilized the Milliplex Human Neuropeptide Magnetic panel and the Luminex platform. Natural log-transformed orexin A data were analyzed using general linear model adjusting for diagnosis, gender, age, total body fat and body mass index (BMI). Plasma orexin A levels were significantly higher (P < 0.006) in children with PWS (average ±SD = 1028 pg/ml ± 358) compared with unrelated siblings (average ±SD = 609 pg/ml ± 351; P < 0.001). Orexin A levels correlated with age in females and were significantly elevated in PWS even after these effects were controlled. These findings support the hypothesis that dysregulation of orexin signaling may contribute to behavioral problems and hyperphagia in PWS. Further studies are warranted to better understand the complex relationship between orexin A levels and the problematic behaviors consistently found in individuals with PWS. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A matching approach to communicate through the plasma sheath surrounding a hypersonic vehicle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Xiaotian; Jiang, Binhao, E-mail: jiangbh@hit.edu.cn

2015-06-21

In order to overcome the communication blackout problem suffered by hypersonic vehicles, a matching approach has been proposed for the first time in this paper. It utilizes a double-positive (DPS) material layer surrounding a hypersonic vehicle antenna to match with the plasma sheath enclosing the vehicle. Analytical analysis and numerical results indicate a resonance between the matched layer and the plasma sheath will be formed to mitigate the blackout problem in some conditions. The calculated results present a perfect radiated performance of the antenna, when the match is exactly built between these two layers. The effects of the parameters ofmore » the plasma sheath have been researched by numerical methods. Based on these results, the proposed approach is easier to realize and more flexible to the varying radiated conditions in hypersonic flight comparing with other methods.« less

Application of Stereo Vision to the Reconnection Scaling Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klarenbeek, Johnny; Sears, Jason A.; Gao, Kevin W.

The measurement and simulation of the three-dimensional structure of magnetic reconnection in astrophysical and lab plasmas is a challenging problem. At Los Alamos National Laboratory we use the Reconnection Scaling Experiment (RSX) to model 3D magnetohydrodynamic (MHD) relaxation of plasma filled tubes. These magnetic flux tubes are called flux ropes. In RSX, the 3D structure of the flux ropes is explored with insertable probes. Stereo triangulation can be used to compute the 3D position of a probe from point correspondences in images from two calibrated cameras. While common applications of stereo triangulation include 3D scene reconstruction and robotics navigation, wemore » will investigate the novel application of stereo triangulation in plasma physics to aid reconstruction of 3D data for RSX plasmas. Several challenges will be explored and addressed, such as minimizing 3D reconstruction errors in stereo camera systems and dealing with point correspondence problems.« less

Complexity Reduction of Collisional-Radiative Kinetics for Atomic Plasma

DTIC Science & Technology

2013-12-23

through collisional and radiative interactions .4–6 The most accurate treatment for these non- equilibrium plasmas requires a state-to-state approach,7–13...CR system versus time, during con- stant-Te plasma evolution from a low -temperature ASDF and low electron number density; as excitation and...Collisional-radiative model in air for earth re-entry problems,” Phys. Plasmas 13, 043502 (2006). 9C. O. Laux, L. Pierrot, and R. J. Gessman, “State-to

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Steepening of the density profile under the action of a ponderomotive force during isothermal planar plasma expansion

NASA Astrophysics Data System (ADS)

Garanin, Sergey G.; Kir'yanov, Yu F.; Kochemasov, G. G.

1990-06-01

A theoretical investigation is reported of the deformation of the density profile of a plasma by a ponderomotive force under transient conditions. Initially, the structure of the density profile near the critical point coincides exactly with the solution of the steady-state problem. Plasma expansion is accompanied by growth of a spiky instability in the form of stimulated Brillouin scattering.

Plasma chemistry as a tool for green chemistry, environmental analysis and waste management.

PubMed

Mollah, M Y; Schennach, R; Patscheider, J; Promreuk, S; Cocke, D L

2000-12-15

The applications of plasma chemistry to environmental problems and to green chemistry are emerging fields that offer unique opportunities for advancement. There has been substantial progress in the application of plasmas to analytical diagnostics and to waste reduction and waste management. This review discusses the chemistry and physics necessary to a basic understanding of plasmas, something that has been missing from recent technical reviews. The current status of plasmas in environmental chemistry is summarized and emerging areas of application for plasmas are delineated. Plasmas are defined and discussed in terms of their properties that make them useful for environmental chemistry. Information is drawn from diverse fields to illustrate the potential applications of plasmas in analysis, materials modifications and hazardous waste treatments.

Time-Domain Finite Element Analysis of Nonlinear Breakdown Problems in High-Power-Microwave Devices and Systems

DTIC Science & Technology

2015-12-24

simulation of the electromagnetic- plasma interaction and the high-power microwave breakdown in air. Under the high pressure and high frequency condition of...the high-power air breakdown, the physical phenomenon is described using a nonlinearly coupled full-wave Maxwell and fluid plasma system. This...Challenges ........................................................................... 3 3.1.1 Plasma Fluid Model

Comment on “Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma” [Phys. Plasmas 20, 072703 (2013)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habibi, M., E-mail: habibi.physics@gmail.com; Ghamari, F.

2014-06-15

Patil and Takale in their recent article [Phys. Plasmas 20, 072703 (2013)], by evaluating the quantum dielectric response in thermal quantum plasma, have modeled the relativistic self-focusing of Gaussian laser beam in a plasma. We have found that there are some important shortcomings and fundamental mistakes in Patil and Takale [Phys. Plasmas 20, 072703 (2013)] that we give a brief description about them and refer readers to important misconception about the use of the Fermi temperature in quantum plasmas, appearing in Patil and Takale [Phys. Plasmas 20, 072703 (2013)].

Research on the FDTD method of scattering effects of obliquely incident electromagnetic waves in time-varying plasma sheath on collision and plasma frequencies

NASA Astrophysics Data System (ADS)

Chen, Wei; Guo, Li-xin; Li, Jiang-ting

2017-04-01

This study analyzes the scattering characteristics of obliquely incident electromagnetic (EM) waves in a time-varying plasma sheath. The finite-difference time-domain algorithm is applied. According to the empirical formula of the collision frequency in a plasma sheath, the plasma frequency, temperature, and pressure are assumed to vary with time in the form of exponential rise. Some scattering problems of EM waves are discussed by calculating the radar cross section (RCS) of the time-varying plasma. The laws of the RCS varying with time are summarized at the L and S wave bands.

Modernized active spectroscopic diagnostics (CXRS) of the T-10 tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupin, V. A., E-mail: Krupin-VA@nrcki.ru; Klyuchnikov, L. A., E-mail: Lklyuchnikov@list.ru; Korobov, K. V., E-mail: Korobov-KV@nrcki.ru

2015-12-15

This work presents the results of modernization of the CXRS (charge exchange recombination spectroscopy) diagnostics [1] at the T-10 tokamak. The relevance of this work is due to the importance of measurements of the ion temperature and nuclei density of the working gas and impurities for analysis of transport processes in the plasma ion component. Measurements of radial profiles of the ion temperature are extremely important for investigating the geodesic acoustic mode behavior which is conducted at the T-10 [2]. The modernized scheme of CXRS measurements, as well as the design and operational features of the spectrometer created for themore » new diagnostics, is described. Principles of data recording and further processing are considered in detail; attention is given to the problem of calibration of the whole complex of equipment. The performed changes in diagnostics allow the measurements to be taken simultaneously in three spectral intervals: in the region of the beam line H{sub α}, the CXRS line of carbon ion C{sup 5+}, and the CXRS line of one of the hydrogen-like ions: He{sup 1+}, Li{sup 2+}, N{sup 6+}, O{sup 7+} or Ne{sup 9+}. This makes it possible to measure the density profiles of two plasma impurities simultaneously, as well as the ion temperature from CXRS lines of different elements. The modernized diagnostics significantly broadens the possibilities of studying the physics of transport processes and quasi-coherent modes of plasma oscillations at the T-10.« less

Laboratory Study of the Shaping and Evolution of Magnetized Episodic Plasma Jets

NASA Astrophysics Data System (ADS)

Higginson, Drew

2015-11-01

The expansion of hot, dense plasma (100 eV, 1018 cm-3) into vacuum occupied by a strong magnetic field (β =Pkinetic /Pmag ~ 1) along the expansion axis is a seemingly elementary physics problem, yet it is one that has scarcely been investigated. As well as being a fundamental problem in plasma physics, understanding such a situation is important to provide an explanation of large-scale jets observed in the formation of young stellar objects (YSO). Additionally, the ability to manipulate such a situation (e.g. to optimize x-ray emission) may be essential to the feasibility of recently proposed inertial confinement fusion (ICF) schemes with an imposed magnetic field. To investigate these situations, a CF2 foil is irradiated with the ELFIE laser (1013 W/cm2, 0.6 ns) in an external axial magnetic field of 20 T. As the plasma expands radially it is restricted by magnetic pressure that creates a cavity with a shock at the expansion edge. This shock redirects flow back on axis and creates a strong, stationary, conical shock that collimates the flow into a jet traveling over 1000 km/s and extending many centimeters. The effect of episodic heating (e.g. from variable mass ejection in a YSO, or pulse shaping in ICF) was investigated by irradiating the target with a precursor laser (1012 W/cm2, 0.6 ns) at 9 to 19 ns prior to the main pulse. The addition of this relatively small addition of energy (<20% of the main pulse energy) changed the dynamics of the expansion dramatically by increasing the strength of the conical shock, reducing the forward expansion of the cavity and dramatically increasing emission. We also present MHD simulations that reproduce the experimental observables and help to understand dynamics of jet and cavity formation. Prepared by LLNL under Contract DE-AC52-07NA27344. Presently at Lawrence Livermore National Laboratory.

Evaluation of vitamin D prophylaxis in 3-36-month-old infants and children.

PubMed

Ozcan, Alper; Kendirci, Mustafa; Kondolot, Meda; Kardas, Fatih; Akın, Leyla

2017-05-01

Vitamin D (VD) deficiency (VDD) is still a population-based health problem that affects people at different ages. The aim of this study was to evaluate VD prophylaxis for the prevention of VDD in (3-36)-month-old infants and children. Infants and children aged between 3 and 36 months, with different etiologies, admitted to outpatient and inpatient clinics from October 2010 to October 2011 at the Children's Hospital of Erciyes University, were enrolled for the study. Their VD intake (if used; time of initiation, dosage and compliance) and nutritional status (breast-fed, formula or complementary fed) were noted. In order to study seasonal VD changes, the levels of serum calcium, phosphorus and magnesium, alkaline phosphatase activity (PLA), plasma parathyroid hormone (PTH) and 25 hydroxyvitamin 25(OH)D levels were measured at the beginning of VD supplementation during the four seasons. A total of 316 subjects were enrolled in the study, consisting of 202 (63.9%) outpatient and 114 (26.1%) inpatient groups. From these subjects, 304 (96.2%) were supplemented with VD; whereas 12 (3.8%) were not. Out of the subjects supplemented with VD, 237 (75%) initiated VD after the second week of life, 267 (87.8%) were given three drops of VD daily and 209 (66.1%) had taken VD regularly. The plasma 25(OH)D levels were found to be lower in the inpatient group than the outpatient group (29.35 ng/mL and 34.35 ng/mL, respectively). The plasma 25(OH)D levels were lower during the spring and winter. VDD and VD insufficiency (VDI) was found in 31 (9.8%) and 30 (9.5%) subjects, respectively. The plasma 25(OH)D levels were lower in inpatient and breast-fed only subjects and in winter and spring. The national VD augmentation program seems to be beneficial for the prevention of VDD, but VDD/VDI seems to still be an important health problem.

BOOK REVIEW: Introduction to Plasma Physics: With Space and Laboratory Applications

NASA Astrophysics Data System (ADS)

Browning, P. K.

2005-07-01

A new textbook on plasma physics must be very welcome, as this will encourage the teaching of courses on the subject. This book is written by two experts in their fields, and is aimed at advanced undergraduate and postgraduate courses. There are of course many other plasma physics textbooks available. The niche which this particular book fills is really defined by its subtitle: that is, `with space and laboratory applications'. This differs from most other books which tend to emphasise either space or fusion applications (but not both) or to concentrate only on general theory. Essentially, the emphasis here is on fundamental plasma physics theory, but applications are given from time to time. For example, after developing Alfvén wave theory, observations of Alfvén waves in the solar wind and in the Jovian magnetosphere are presented; whilst ion acoustic cylcotron waves are illustrated by data from a laboratory Q machine. It is fair to say that examples from space seem to predominate. Nevertheless, the approach of including a broad range of applications is very good from an educational point of view, and this should help to train a generation of students with a grasp of fundamental plasma physics who can work in a variety of research fields. The subject coverage of the book is fairly conventional and there are no great surprises. It begins, inevitably, with a discussion of plasma parameters (Debye length etc) and of single particle motions. Both kinetic theory and magnetohydrodynamics are introduced. Waves are quite extensively discussed in several chapters, including both cold and hot plasmas, magnetised and unmagnetised. Nonlinear effects—a large subject!—are briefly discussed. A final chapter deals with collisions in fully ionised plasmas. The choice of contents of a textbook is always something of a matter of personal choice. It is easy to complain about what has been left out, and everyone has their own favourite topics. With that caveat, I would question whether the rather heavy emphasis on waves is optimal. Newcomers to plasma physics could be left with the impression that plasma physics is mainly a collection of dispersion relations. On the other hand, there is almost no mention of two fluid theory, surely an important subject. Topics relevant to fusion edge plasmas, a subject of growing research interest, are not mentioned at all (for example, sheath theory; also partially ionised plasmas, which are also of course very relevant in space applications). And I am surprised that the discussion of MHD stability does not even mention the kink instability, which is of primary importance both in fusion and solar plasmas. The book is clearly set out and easy to read. Diagrams are clear and helpful. Derivations are properly explained, without leaving too many missing steps. From the point of view of a textbook, it is useful that not too much mathematical knowledge is assumed; for example, when it is needed, the theory of Laplace transforms is explained. A nice feature—very important for a text book—is the presence of end-of-chapter problems. These will be very useful for both students and teachers! It is also good that each chapter has a comprehensive list of references, which might be used to direct more advanced students to the up-to-date scientific literature, as well as suggestions for further reading. Although the primary emphasis is on standard, `classical' plasma physics, a good attempt is made to present more recent aspects of the subject. For example, after presenting the standard theory of particle orbits—which usefully includes a discussion of Hamiltonian theory as well as guiding centre theory—there is an introduction to the topic of chaotic orbits. Such material is important from an educational point of view, so that from the very beginning students are made aware that plasma physics is a living subject. Overall, this is a very useful addition to the literature. I would recommend it for adoption as a course text for those teaching courses in plasma physics. It would also be a useful book for reference or self study for those working in the field, particularly new postgraduate students.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahlburg, Jill; Corones, James; Batchelor, Donald

Fusion is potentially an inexhaustible energy source whose exploitation requires a basic understanding of high-temperature plasmas. The development of a science-based predictive capability for fusion-relevant plasmas is a challenge central to fusion energy science, in which numerical modeling has played a vital role for more than four decades. A combination of the very wide range in temporal and spatial scales, extreme anisotropy, the importance of geometric detail, and the requirement of causality which makes it impossible to parallelize over time, makes this problem one of the most challenging in computational physics. Sophisticated computational models are under development for many individualmore » features of magnetically confined plasmas and increases in the scope and reliability of feasible simulations have been enabled by increased scientific understanding and improvements in computer technology. However, full predictive modeling of fusion plasmas will require qualitative improvements and innovations to enable cross coupling of a wider variety of physical processes and to allow solution over a larger range of space and time scales. The exponential growth of computer speed, coupled with the high cost of large-scale experimental facilities, makes an integrated fusion simulation initiative a timely and cost-effective opportunity. Worldwide progress in laboratory fusion experiments provides the basis for a recent FESAC recommendation to proceed with a burning plasma experiment (see FESAC Review of Burning Plasma Physics Report, September 2001). Such an experiment, at the frontier of the physics of complex systems, would be a huge step in establishing the potential of magnetic fusion energy to contribute to the world’s energy security. An integrated simulation capability would dramatically enhance the utilization of such a facility and lead to optimization of toroidal fusion plasmas in general. This science-based predictive capability, which was cited in the FESAC integrated planning document (IPPA, 2000), represents a significant opportunity for the DOE Office of Science to further the understanding of fusion plasmas to a level unparalleled worldwide.« less

EDITORIAL: Gas plasmas in biology and medicine

NASA Astrophysics Data System (ADS)

Stoffels, Eva

2006-08-01

It is my great pleasure to introduce this special cluster devoted to recent developments in biomedical plasma technology. It is an even greater pleasure to behold the enormous progress which has been made in this area over the last five years. Research on biomedical plasma applications proceeds hand in hand with the development of new material processing technologies, based on atmospheric plasma sources. In the beginning, major research effort was invested in the development and control of new plasma sources—in this laborious process, novel devices were constructed and characterized, and also new plasma physical phenomena were discovered. Self-constriction of micro-plasmas, pattern formation, filamentation of glow discharges and various mode transitions are just a few examples. It is a real challenge for theorists to gain an understanding of these complex phenomena. Later, the devices had to be thoroughly tested and automated, and various safety issues had to be addressed. At present, many atmospheric plasma sources are ready to use, but not all fundamental and technical problems have been resolved by far. There is still plenty of room for improvement, as in any dynamic area of research. The recent trends are clear: the application area of plasmas expands into processing of unconventional materials such as biological scaffolds, and eventually living human, animal and plant tissues. The gentle, precise and versatile character of cold plasmas simply invites this new application. Firstly, non-living surfaces have been plasma-treated to attain desired effects in biomedical research; tissue engineering will soon fully profit from this powerful technique. Furthermore, studies on cultured plant and animal cells have provided many findings, which are both fundamentally interesting and potentially applicable in health care, veterinary medicine and agriculture. The most important and hitherto unique property of plasma treatment is that it can evade accidental cell death and its attendant complications, such as inflammation and scarring. Another substantial research direction makes use of the bactericidal properties of the plasma. The number of findings on plasma inactivation of bacteria and spores is growing; plasma sterilization has already achieved some commercial success. In future, bacteriostatic properties of cold plasmas will even facilitate non-contact disinfection of human tissues. At this moment, one cannot explicitly list all the medical procedures in which cold plasmas will be involved. My personal intuition predicts widespread use of plasma treatment in dentistry and dermatology, but surely more applications will emerge in the course of this multi-disciplinary research. In fact, some plasma techniques, such as coagulation and coblation, are already used in clinical practice—this is another image of plasma science, which is so far unfamiliar to plasma physicists. Therefore, this particular topic forms a perfect platform for contacts between physicists and medical experts. Our colleagues from the medical scientific community will continue giving us feedback, suggestions or even orders. Biomedical plasmas should not become an isolated research area—we must grow together with medical research, listen to criticism, and eventually serve the physicians. Only then will this new field grow, flourish and bear fruit. All the above-mentioned topics meet in this issue of Journal of Physics D: Applied Physics, comprising the most significant examples of modern biomedical plasma research. Browsing through the contributions, the reader can trace back the progress in this field: from fundamental physical (numerical) studies, through phenomenology and physics of new discharges, studies on plasma-surface modification, bacterial inactivation tests, fundamental cell biological investigations, to final in vivo applications. One may ask why this selection has found its place in a purely physical journal—many contributions are concerned with (micro)-biology rather than physics. To me, the answer is clear: it is important to maintain the visibility of this fascinating and growing cross-disciplinary field within the (plasma) physical community. This is not the `physics we are used to', but one we will eventually get used to and accept.

A magnetic boundary layer at the magnetopause

NASA Astrophysics Data System (ADS)

Kartalev, M. D.; Simeonov, G.

A new approach in the boundary layer description of the magnetopause is proposed. The magnetopause is considered as a mixing region of two streams of plasma with different parameters. The assumption is made that wave-particle interactions cause the plasma to be resistive. Thus only the magnetic viscosity is supposed to be essential. Other dissipation effects are neglected. The plasma and magnetic field conditions at the outer boundary of the layer can be obtained from the solution of the nondissipative problem for the magnetosheath. The magnetic field is assumed to be known at the inner boundary. No further conditions are needed in our formulation of the problem. The variation of the flow parameters and the magnetic field can be obtained numerically.

Therapeutic role of vasopressin receptor antagonism in patients with liver cirrhosis.

PubMed

Ferguson, James Walter; Therapondos, George; Newby, David E; Hayes, Peter Clive

2003-07-01

Vasopressin, or antidiuretic hormone, is a peptide hormone that is released from the posterior pituitary gland in response to changes in blood pressure and plasma osmolality. The main pathophysiological states associated with high plasma vasopressin concentrations are cirrhosis, cardiac failure and syndrome of inappropriate antidiuretic hormone (SIADH) secretion. Pharmacological treatments for disorders of excess vasopressin secretion have been limited. However, oral bio-available selective and non-selective V(1) and V(2) receptor antagonists have recently become available for clinical use. Water retention in cirrhosis is a common problem, leading to ascites, peripheral oedema and hyponatraemia. Raised plasma vasopressin concentrations and decreased delivery of glomerular filtrate are believed to be the most important factors in the development of water retention. V(2) receptor antagonists are aquaretic agents that promote water excretion and improve hyponatraemia. Their potential role in cirrhosis has been examined in a number of recent studies that have shown increased free water clearance and serum sodium concentrations with few adverse effects. V(2) receptor antagonists represent a novel and promising new class of agent that may have major clinical utility in the treatment of patients with liver cirrhosis.

Laser correlation spectrometry: a new approach to organizing oncological screening for a population exposed to chronic irradiation

NASA Astrophysics Data System (ADS)

Akleyev, Alexander; Pashkov, Igor; Kisselyov, Mikhail; Noskin, Leonid A.

1999-12-01

The issue of stochastic effects of radiation exposure (mostly leukemia and cancer), and early detection of malignant tumors, as a key aspect of the problem, is of crucial importance to the population chronically exposed due to the activities of the Mayak Production Association in the Urals region, Russia). Given the large number of exposed population, screening is considered to be the most expedient method to organize medical observation of exposed persons. As was shown by the results of medical examinations conducted for 1 391 residents of the Techa riverside villages, laser correlation spectrometry (LCS) of blood plasma has proved to be a highly effective screening method for early (pre-clinical) detection of malignant neoplasms and pre-cancerous conditions. It was established that LC- spectra of blood plasma in persons with cancer and pre- cancer can easily be differentiated from non-cancer conditions. Of particular diagnostic significance is the high-frequency range of the spectrum. The development of a diagnostic algorithm has allowed to carry out a computer- based classification of blood plasma LC spectra as a component of exposed population health monitoring system.

Collisional PIC Simulations of Particles in Magnetic Fields

NASA Astrophysics Data System (ADS)

Peter, William

2003-10-01

Because of the long range of Coloumb forces, collisions with distant particles in plasmas are more important than collisions with near neighbors. In addition, many problems in space physics and magnetic confinement include regions of weak magnetic field where the MHD approximation breaks down. A particle-in-cell code based on the quiet direct simulation Monte-Carlo method(B. J. Albright, W. Daughton, D. Lemons, D. Winske, and M. E. Jones, Physics of Plasmas) 9, 1898 (2002). is being developed to study collisional (e.g., ν ˜ Ω) particle motion in magnetic fields. Primary application is to energetic particle loss in the radiation belts(K. Papadopoulos, COSPAR Meeting, Houston, TX, Oct., 2002.) at a given energy and L-shell. Other applications include trapping in rotating field-reversed configurations(N. Rostoker and A. Qerushi, Physics of Plasmas) 9, 3057 (2002)., and electron behavior in magnetic traps(V. Gorgadze, T. Pasquini, J. S. Wurtele, and J. Fajans, Bull. Am. Phys. Soc.) 47, 127 (2002).. The use of the random time-step method(W. Peter, Bull. Am. Phys. Soc.) 47, 52 (2002). to decrease simulation times by 1-2 orders of magnitude is also being studied.

Global Simulations of Dynamo and Magnetorotational Instability in Madison Plasma Experiments and Astrophysical Disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebrahimi, Fatima

2014-07-31

Large-scale magnetic fields have been observed in widely different types of astrophysical objects. These magnetic fields are believed to be caused by the so-called dynamo effect. Could a large-scale magnetic field grow out of turbulence (i.e. the alpha dynamo effect)? How could the topological properties and the complexity of magnetic field as a global quantity, the so called magnetic helicity, be important in the dynamo effect? In addition to understanding the dynamo mechanism in astrophysical accretion disks, anomalous angular momentum transport has also been a longstanding problem in accretion disks and laboratory plasmas. To investigate both dynamo and momentum transport,more » we have performed both numerical modeling of laboratory experiments that are intended to simulate nature and modeling of configurations with direct relevance to astrophysical disks. Our simulations use fluid approximations (Magnetohydrodynamics - MHD model), where plasma is treated as a single fluid, or two fluids, in the presence of electromagnetic forces. Our major physics objective is to study the possibility of magnetic field generation (so called MRI small-scale and large-scale dynamos) and its role in Magneto-rotational Instability (MRI) saturation through nonlinear simulations in both MHD and Hall regimes.« less

Electron-acoustic rogue waves in a plasma with Tribeche–Tsallis–Cairns distributed electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Merriche, Abderrzak; Tribeche, Mouloud, E-mail: mouloudtribeche@yahoo.fr; Algerian Academy of Sciences and Technologies, Algiers

2017-01-15

The problem of electron-acoustic (EA) rogue waves in a plasma consisting of fluid cold electrons, nonthermal nonextensive electrons and stationary ions, is addressed. A standard multiple scale method has been carried out to derive a nonlinear Schrödinger-like equation. The coefficients of dispersion and nonlinearity depend on the nonextensive and nonthermal parameters. The EA wave stability is analyzed. Interestingly, it is found that the wave number threshold, above which the EA wave modulational instability (MI) sets in, increases as the nonextensive parameter increases. As the nonthermal character of the electrons increases, the MI occurs at large wavelength. Moreover, it is shownmore » that as the nonextensive parameter increases, the EA rogue wave pulse grows while its width is narrowed. The amplitude of the EA rogue wave decreases with an increase of the number of energetic electrons. In the absence of nonthermal electrons, the nonextensive effects are more perceptible and more noticeable. In view of the crucial importance of rogue waves, our results can contribute to the understanding of localized electrostatic envelope excitations and underlying physical processes, that may occur in space as well as in laboratory plasmas.« less

Bayesian Inference of Physics Parameters in the DIII-D Charge-Exchange Recombination Spectroscopy System

NASA Astrophysics Data System (ADS)

Bowman, C.; Gibson, K. J.; La Haye, R. J.; Groebner, R. J.; Taylor, N. Z.; Grierson, B. A.

2014-10-01

A Bayesian inference framework has been developed for the DIII-D charge-exchange recombination (CER) system, capable of computing probability distribution functions (PDFs) for desired parameters. CER is a key diagnostic system at DIII-D, measuring important physics parameters such as plasma rotation and impurity ion temperature. This work is motivated by a case in which the CER system was used to probe the plasma rotation radial profile around an m/n = 2/1 tearing mode island rotating at ~ 1 kHz. Due to limited resolution in the tearing mode phase and short integration time, it has proven challenging to observe the structure of the rotation profile across the island. We seek to solve this problem by using the Bayesian framework to improve the estimation accuracy of the plasma rotation, helping to reveal details of how it is perturbed in the magnetic island vicinity. Examples of the PDFs obtained through the Bayesian framework will be presented, and compared with results from a conventional least-squares analysis of the CER data. Work supported by the US DOE under DE-FC02-04ER54698 and DE-AC02-09CH11466.

Nonlinear Burn Control in Tokamaks using Heating, Non-axisymmetric Magnetic Fields, Isotopic fueling and Impurity injection

NASA Astrophysics Data System (ADS)

Pajares, Andres; Schuster, Eugenio

2016-10-01

Plasma density and temperature regulation in future tokamaks such as ITER is arising as one of the main problems in nuclear-fusion control research. The problem, known as burn control, is to regulate the amount of fusion power produced by the burning plasma while avoiding thermal instabilities. Prior work in the area of burn control considered different actuators, such as modulation of the auxiliary power, modulation of the fueling rate, and controlled impurity injection. More recently, the in-vessel coil system was suggested as a feasible actuator since it has the capability of modifying the plasma confinement by generating non-axisymmetric magnetic fields. In this work, a comprehensive, model-based, nonlinear burn control strategy is proposed to integrate all the previously mentioned actuators. A model to take into account the influence of the in-vessel coils on the plasma confinement is proposed based on the plasma collisionality and the density. A simulation study is carried out to show the capability of the controller to drive the system between different operating points while rejecting perturbations. Supported by the US DOE under DE-SC0010661.

Bile acid synthesis is increased in Chilean Hispanics with gallstones and in gallstone high-risk Mapuche Indians.

PubMed

Gälman, Cecilia; Miquel, Juan Francisco; Pérez, Rosa Maria; Einarsson, Curt; Ståhle, Lars; Marshall, Guillermo; Nervi, Flavio; Rudling, Mats

2004-03-01

Gallstone disease is an important, costly health-care problem in Western societies. It is still unclear whether hepatic lipid regulatory enzymes play primary or secondary roles in gallstone formation. In this study, the aim was to investigate whether the synthesis of bile acids and cholesterol is increased in gallstone disease and to test whether such a metabolic change, if present, might occur before gallstone formation. A total of 125 Chilean Hispanic women (80 without gallstones and 45 with gallstones) matched for age and body mass index were investigated, along with 40 Chilean Mapuche Indian women (20 without gallstones and 20 with gallstones), a population group in which the prevalence for gallstone disease is very high. Fasting blood plasma samples were assayed for 7 alpha-hydroxy-4-cholesten-3-one and lathosterol, 2 strong indicators for hepatic bile acid and body cholesterol synthesis, respectively. Plasma 7 alpha-hydroxy-4-cholesten-3-one levels, corrected for plasma cholesterol, were significantly increased by 50% in Hispanic women with gallstones as compared with gallstone-free Hispanics (P < 0.006). As compared with Hispanic women without gallstones, plasma 7 alpha-hydroxy-4-cholesten-3-one levels were increased by > or =100% (P < 0.002) in Mapuche Indian women, independently of whether gallstones were present. Plasma lathosterol, corrected for plasma cholesterol, was significantly increased by 22% in Hispanic women with gallstones and in Mapuche Indian women compared with Hispanic women. The results indicate that the synthesis of bile acids and cholesterol is induced in gallstone disease and precedes gallstone development. These inductions presumably occur as a response to an increased intestinal loss of bile acids.

Effects of nuclear forces on ion thermalization in high-temperature plasmas

NASA Technical Reports Server (NTRS)

Gould, R. J.

1982-01-01

A number of investigations have been concerned with the kinetic theory and processes associated with a relativistic electron gas. Gould (1981) has considered a condition in which upon the ultimate thermalization the temperature can be such that the electron gas is highly relativistic while the gas of protons and other ions is nonrelativistic. With the nuclear component nonrelativistic but having energies in the MeV range and above, it is necessary to consider the effects of nuclear forces in the scattering of the ions in their thermalization. The effects of nuclear forces in the thermalization of ions in plasmas have been computed, principally in connection with problems of controlle; fusion. The present investigation is concerned with an attempt to express results in analytic form to as great a degree as possible. The p-p problem, which is the fundamental problem in astrophysical plasma, is studied. Attention is given to a low-energy formulation, the s-wave phase shift, the effective stopping number, Fokker-Planck operators, and the interaction with the electron gas.

Current collection from an unmagnetized plasma: A tutorial

NASA Technical Reports Server (NTRS)

Whipple, Elden C.

1990-01-01

The current collected by a body in an unmagnetized plasma depends in general on: (1) the properties of the plasma; (2) the properties of the body; and (3) the properties of any neutral species that are present. The important plasma properties are the velocity distributions of the plasma particles at a location remote from the body (at infinity), and the Debye length which determines the importance of plasma space charge effects. The important body properties are its surface characteristics, namely the conductivity and secondary yield coefficients. The neutral species affect the current through collisions which impede the flow of current and possibly through ionization of the neutrals which can enhance the current. The technique for calculating the current collected by a body in a plasma is reviewed with special attention given to the distinction between orbit limited and space charge limited regimes, the asymptotic variation of the potential with distance from a body, and the concept of a sheath.

Simulator test to study hot-flow problems related to a gas cooled reactor

NASA Technical Reports Server (NTRS)

Poole, J. W.; Freeman, M. P.; Doak, K. W.; Thorpe, M. L.

1973-01-01

An advance study of materials, fuel injection, and hot flow problems related to the gas core nuclear rocket is reported. The first task was to test a previously constructed induction heated plasma GCNR simulator above 300 kW. A number of tests are reported operating in the range of 300 kW at 10,000 cps. A second simulator was designed but not constructed for cold-hot visualization studies using louvered walls. A third task was a paper investigation of practical uranium feed systems, including a detailed discussion of related problems. The last assignment resulted in two designs for plasma nozzle test devices that could be operated at 200 atm on hydrogen.

Two-phase flows in the formed tornado funnel

NASA Astrophysics Data System (ADS)

Sinkevich, O. A.; Bortsova, A. A.

2017-10-01

At present, it is obvious that the problem of the tornado is important not only for our planetЮ to determine the conditions for the formation of a tornado, it is required to take into account a number of hydrodynamic and plasma processes [1 - 6]. Along to prediction of a tornado generation conditions [1 - 3] it is necessary to evaluate the characteristics of its quasi-stationary motion in a formed funnel: the mass of the moving moist air involved in the funnel and the size and form of the funnel. For a complete description of the phenomena, it is necessary to involve numerical calculations. We note that even for numerical calculations using powerful computers, the problem is very difficult because of the need to calculate multiphase turbulent flows with free, self-organizing boundaries [1, 6]. However, “strict” numerical calculations, it is impossible to do without the use of many, often mutually exclusive, models. For example, how to choice an adequate model of turbulence (algebraic, k-ε model, etc.) or the use of additional, often not accepted, hypotheses about certain processes used in calculations (mechanisms on the nature of moisture condensation, etc.). Therefore, along with numerical calculations of such flows, modeling problems that allow an exact solution and allow to determine the most important and observed characteristics of a tornado.

Implicit Plasma Kinetic Simulation Using The Jacobian-Free Newton-Krylov Method

NASA Astrophysics Data System (ADS)

Taitano, William; Knoll, Dana; Chacon, Luis

2009-11-01

The use of fully implicit time integration methods in kinetic simulation is still area of algorithmic research. A brute-force approach to simultaneously including the field equations and the particle distribution function would result in an intractable linear algebra problem. A number of algorithms have been put forward which rely on an extrapolation in time. They can be thought of as linearly implicit methods or one-step Newton methods. However, issues related to time accuracy of these methods still remain. We are pursuing a route to implicit plasma kinetic simulation which eliminates extrapolation, eliminates phase-space from the linear algebra problem, and converges the entire nonlinear system within a time step. We accomplish all this using the Jacobian-Free Newton-Krylov algorithm. The original research along these lines considered particle methods to advance the distribution function [1]. In the current research we are advancing the Vlasov equations on a grid. Results will be presented which highlight algorithmic details for single species electrostatic problems and coupled ion-electron electrostatic problems. [4pt] [1] H. J. Kim, L. Chac'on, G. Lapenta, ``Fully implicit particle in cell algorithm,'' 47th Annual Meeting of the Division of Plasma Physics, Oct. 24-28, 2005, Denver, CO

Rapid quantification of underivatized amino acids in plasma by hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass-spectrometry.

PubMed

Prinsen, Hubertus C M T; Schiebergen-Bronkhorst, B G M; Roeleveld, M W; Jans, J J M; de Sain-van der Velden, M G M; Visser, G; van Hasselt, P M; Verhoeven-Duif, N M

2016-09-01

Amino acidopathies are a class of inborn errors of metabolism (IEM) that can be diagnosed by analysis of amino acids (AA) in plasma. Current strategies for AA analysis include cation exchange HPLC with post-column ninhydrin derivatization, GC-MS, and LC-MS/MS-related methods. Major drawbacks of the current methods are time-consuming procedures, derivative problems, problems with retention, and MS-sensitivity. The use of hydrophilic interaction liquid chromatography (HILIC) columns is an ideal separation mode for hydrophilic compounds like AA. Here we report a HILIC-method for analysis of 36 underivatized AA in plasma to detect defects in AA metabolism that overcomes the major drawbacks of other methods. A rapid, sensitive, and specific method was developed for the analysis of AA in plasma without derivatization using HILIC coupled with tandem mass-spectrometry (Xevo TQ, Waters). Excellent separation of 36 AA (24 quantitative/12 qualitative) in plasma was achieved on an Acquity BEH Amide column (2.1×100 mm, 1.7 μm) in a single MS run of 18 min. Plasma of patients with a known IEM in AA metabolism was analyzed and all patients were correctly identified. The reported method analyzes 36 AA in plasma within 18 min and provides baseline separation of isomeric AA such as leucine and isoleucine. No separation was obtained for isoleucine and allo-isoleucine. The method is applicable to study defects in AA metabolism in plasma.

Die Virus-induzierten Lebererkrankungen des Menschen

NASA Astrophysics Data System (ADS)

Eisenburg, J.

1982-12-01

Although many viral agents may be associated with inflammatory hepatic changes, the vast majority of clinically important viral hepatitis is caused by hepatitis A, hepatitis B and the non A, non B agents. Infection of the liver of man by these hepatotropic agents is still a major public health problem in all parts of the world and constitutes a major hazard of the transfusion of blood and plasma derivatives. The magnitude of this hepatitis problem is not only documented by the about 200 million carriers of the hepatitis-B virus throughout the world, many of them asymptomatic, but also by the fact, that hepatitis B and non A, non B may progress to chronic liver disease, including cirrhosis and probably primary liver cancer. Potentially important pathogenetic determinants include viral factors such as subtype, dosage and mode of transmission and host factors such as age, sex, preexisting liver disease, coexisting non-liver disease (diabetes etc.), genetics and immune response to viral or autoantigens. As the virus itself seems not directly cytopathic, the diversity of lesions has been attributed to variation in the capacity of the host's response.

Neutron generation from Z-pinches

NASA Astrophysics Data System (ADS)

Vikhrev, V. V.; Korolev, V. D.

2007-05-01

Recent advances in both experimental and theoretical studies on neutron generation in various Z-pinch facilities are reviewed. The main methods for enhancing neutron emission from the Z-pinch plasma are described, and the problems of igniting a thermonuclear burn wave in this plasma are discussed.

SAMPIE Measurements of the Space Station Plasma Current Analyzed

NASA Technical Reports Server (NTRS)

1996-01-01

In March of 1994, STS-62 carried the NASA Lewis Research Center's Solar Array Module Plasma Interactions Experiment (SAMPIE) into orbit, where it investigated the plasma current collected and the arcs from solar arrays and other space power materials immersed in the low-Earth-orbit space plasma. One of the important experiments conducted was the plasma current collected by a four-cell coupon sample of solar array cells for the international space station. The importance of this experiment dates back to the 1990 and 1991 meetings of the Space Station Electrical Grounding Tiger Team. The Tiger Team determined that unless the electrical potentials on the space station structure were actively controlled via a plasma contactor, the space station structure would arc into the plasma at a rate that would destroy the thermal properties of its surface coatings in only a few years of operation. The space station plasma contactor will control its potentials by emitting electrons into the surrounding low-Earth-orbit plasma at the same rate that they are collected by the solar arrays. Thus, the level at which the space station solar arrays can collect current is very important in verifying that the plasma contactor design can do its job.

Canonical Descriptions of High Intensity Laser-Plasma Interaction

NASA Astrophysics Data System (ADS)

Le Cornu, B. J.

The problem of laser-plasma interaction has been studied extensively in the context of inertial confinement fusion (ICF). These studies have focussed on effects like the nonlinear force, self-focusing, Rayleigh- Taylor instabilities, stimulated Brillouin scattering and stimulated Raman scattering observed in ICF schemes. However, there remains a large discrepancy between theory and experiment in the context of nuclear fusion schemes. Several authors have attempted to gain greater understanding of the physics involved by the application of standard or 'canonical' methods used in Lagrangian and Hamiltonian mechanics to the problem of plasma physics. This thesis presents a new canonical description of laser-plasma interaction based on the Podolsky Lagrangian. Finite self-energy of charged particles, incroporation of high-frequency effects and an ability to quantise are the main advantages of this new model. The nature of the Podolsky constant is also analysed in the context of plasma physics, specifically in terms of the plasma dispersion relation. A new gauge invariant expression of the energy-momentum tensor for any gauge invariant Lagrangian dependent on second order derivatives is derived for the first time. Finally, the transient and nontransient expressions of the nonlinear ponderomotive force in laser-plasma interaction are discussed and shown to be closely approximated by a canonical derivation of the electromagnetic Lagrangian, a fact that seems to have been missed in the literature.

Laser-absorption effect on pulse-compression under Ohmic and weak-relativistic ponderomotive nonlinearity in plasmas

NASA Astrophysics Data System (ADS)

Singh, Mamta; Gupta, D. N.

2018-01-01

The inclusion of laser absorption in plasmas plays an important role in laser-plasma interactions. In this work, the laser pulse compression in weakly relativistic plasmas has been revisited by incorporating the collision-based laser absorption effects. By considering the role of laser absorption in plasmas, a set of coupled nonlinear equations is derived to describe the evolution of pulse compression. The laser pulse compression is reduced due to the collisional absorption in the plasmas. Fast dispersion is also observed with increasing the absorption coefficient, which is obviously due to the strong energy attenuation in plasmas. Using our theoretical model, the involvement and importance of a particular absorption mechanism for pulse compression in plasmas is analyzed.

Plasmas for environmental issues: from hydrogen production to 2D materials assembly

NASA Astrophysics Data System (ADS)

Tatarova, E.; Bundaleska, N.; Sarrette, J. Ph; Ferreira, C. M.

2014-12-01

It is well recognized at present that the unique, high energy density plasma environment provides suitable conditions to dissociate/atomize molecules in remediation systems, to convert waste and biomass into sustainable energy sources, to purify water, to assemble nanostructures, etc. The remarkable plasma potential is based on its ability to supply simultaneously high fluxes of charged particles, chemically active molecules, radicals (e.g. O, H, OH), heat, highly energetic photons (UV and extreme UV radiation), and strong electric fields in intrinsic sheath domains. Due to this complexity, low-temperature plasma science and engineering is a huge, highly interdisciplinary field that spans many research disciplines and applications across many areas of our daily life and industrial activities. For this reason, this review deals only with some selected aspects of low-temperature plasma applications for a clean and sustainable environment. It is not intended to be a comprehensive survey, but just to highlight some important works and achievements in specific areas. The selected issues demonstrate the diversity of plasma-based applications associated with clean and sustainable ambiance and also show the unity of the underlying science. Fundamental plasma phenomena/processes/features are the common fibers that pass across all these areas and unify all these applications. Browsing through different topics, we try to emphasize these phenomena/processes/features and their uniqueness in an attempt to build a general overview. The presented survey of recently published works demonstrates that plasma processes show a significant potential as a solution for waste/biomass-to-energy recovery problems. The reforming technologies based on non-thermal plasma treatment of hydrocarbons show promising prospects for the production of hydrogen as a future clean energy carrier. It is also shown that plasmas can provide numerous agents that influence biological activity. The simultaneous generation in water discharges of intense UV radiation, shock waves and active radicals (OH, O, H2O2, etc), which are all effective agents against many biological pathogens and harmful chemicals, make these discharges suitable for decontamination, sterilization and purification processes. Moreover, plasmas appear as invaluable tools for the synthesis and engineering of new nanomaterials and in particular 2D materials. A brief overview on plasma-synthesized carbon nanostructures shows the high potential of such materials for energy conversion and storage applications.

Fabrication and surface modification of macroporous poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds for human skin fibroblast cell culture.

PubMed

Yang, Jian; Shi, Guixin; Bei, Jianzhong; Wang, Shenguo; Cao, Yilin; Shang, Qingxin; Yang, Guanghui; Wang, Wenjing

2002-12-05

The fabrication and surface modification of a porous cell scaffold are very important in tissue engineering. Of most concern are high-density cell seeding, nutrient and oxygen supply, and cell affinity. In the present study, poly(L-lactic acid) and poly(L-lactic-co-glycolic acid) (70/30) cell scaffolds with different pore structures were fabricated. An improved method based on Archimedes' Principle for measuring the porosity of scaffolds, using a density bottle, was developed. Anhydrous ammonia plasma treatment was used to modify surface properties to improve the cell affinity of the scaffolds. The results show that hydrophilicity and surface energy were improved. The polar N-containing groups and positive charged groups also were incorporated into the sample surface. A low-temperature treatment was used to maintain the plasma-modified surface properties effectively. It would do help to the further application of plasma treatment technique. Cell culture results showed that pores smaller than 160 microm are suitable for human skin fibroblast cell growth. Cell seeding efficiency was maintained at above 99%, which is better than the efficiency achieved with the common method of prewetting by ethanol. The plasma-treatment method also helped to resolve the problem of cell loss during cell seeding, and the negative effects of the ethanol trace on cell culture were avoided. The results suggest that anhydrous ammonia plasma treatment enhances the cell affinity of porous scaffolds. Mass transport issues also have been considered. Copyright 2002 Wiley Periodicals, Inc.

Transport in zonal flows in analogous geophysical and plasma systems

NASA Astrophysics Data System (ADS)

del-Castillo-Negrete, Diego

1999-11-01

Zonal flows occur naturally in the oceans and the atmosphere of planets. Important examples include the zonal flows in Jupiter, the stratospheric polar jet in Antarctica, and oceanic jets like the Gulf Stream. These zonal flows create transport barriers that have a crucial influence on mixing and confinement (e.g. the ozone depletion in Antarctica). Zonal flows also give rise to long-lasting vortices (e.g. the Jupiter red spot) by shear instability. Because of this, the formation and stability of zonal flows and their role on transport have been problems of great interest in geophysical fluid dynamics. On the other hand, zonal flows have also been observed in fusion plasmas and their impact on the reduction of transport has been widely recognized. Based on the well-known analogy between Rossby waves in quasigeostrophic flows and drift waves in magnetically confined plasmas, I will discuss the relevance to fusion plasmas of models and experiments recently developed in geophysical fluid dynamics. Also, the potential application of plasma physics ideas to geophysical flows will be discussed. The role of shear in the suppression of transport and the effect of zonal flows on the statistics of transport will be studied using simplified models. It will be shown how zonal flows induce large particle displacements that can be characterized as Lévy flights, and that the trapping effect of vortices combined with the zonal flows gives rise to anomalous diffusion and Lévy (non-Gaussian) statistics. The models will be compared with laboratory experiments and with atmospheric and oceanographic qualitative observations.

A blended continuous–discontinuous finite element method for solving the multi-fluid plasma model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sousa, E.M., E-mail: sousae@uw.edu; Shumlak, U., E-mail: shumlak@uw.edu

The multi-fluid plasma model represents electrons, multiple ion species, and multiple neutral species as separate fluids that interact through short-range collisions and long-range electromagnetic fields. The model spans a large range of temporal and spatial scales, which renders the model stiff and presents numerical challenges. To address the large range of timescales, a blended continuous and discontinuous Galerkin method is proposed, where the massive ion and neutral species are modeled using an explicit discontinuous Galerkin method while the electrons and electromagnetic fields are modeled using an implicit continuous Galerkin method. This approach is able to capture large-gradient ion and neutralmore » physics like shock formation, while resolving high-frequency electron dynamics in a computationally efficient manner. The details of the Blended Finite Element Method (BFEM) are presented. The numerical method is benchmarked for accuracy and tested using two-fluid one-dimensional soliton problem and electromagnetic shock problem. The results are compared to conventional finite volume and finite element methods, and demonstrate that the BFEM is particularly effective in resolving physics in stiff problems involving realistic physical parameters, including realistic electron mass and speed of light. The benefit is illustrated by computing a three-fluid plasma application that demonstrates species separation in multi-component plasmas.« less

Computation of solar wind parameters from the OGO-5 plasma spectrometer data using Hermite polynomials

NASA Technical Reports Server (NTRS)

Neugebauer, M.

1971-01-01

The method used to calculate the velocity, temperature, and density of the solar wind plasma is presented from spectra obtained by attitude-stabilized plasma detectors on the earth satellite OGO 5. The method, which used expansions in terms of Hermite polynomials, is very inexpensive to implement on an electronic computer compared to the least-squares and other iterative methods often used for similar problems.

Transparency of an instantaneously created electron-positron-photon plasma

NASA Astrophysics Data System (ADS)

Bégué, D.; Vereshchagin, G. V.

2014-03-01

The problem of the expansion of a relativistic plasma generated when a large amount of energy is released in a small volume has been considered by many authors. We use the analytical solution of Bisnovatyi-Kogan and Murzina for the spherically symmetric relativistic expansion. The light curves and the spectra from transparency of an electron-positron-photon plasma are obtained. We compare our results with the work of Goodman.

Density functional theory calculations of continuum lowering in strongly coupled plasmas.

PubMed

Vinko, S M; Ciricosta, O; Wark, J S

2014-03-24

An accurate description of the ionization potential depression of ions in plasmas due to their interaction with the environment is a fundamental problem in plasma physics, playing a key role in determining the ionization balance, charge state distribution, opacity and plasma equation of state. Here we present a method to study the structure and position of the continuum of highly ionized dense plasmas using finite-temperature density functional theory in combination with excited-state projector augmented-wave potentials. The method is applied to aluminium plasmas created by intense X-ray irradiation, and shows excellent agreement with recently obtained experimental results. We find that the continuum lowering for ions in dense plasmas at intermediate temperatures is larger than predicted by standard plasma models and explain this effect through the electronic structure of the valence states in these strong-coupling conditions.

Ultrahigh-order Maxwell solver with extreme scalability for electromagnetic PIC simulations of plasmas

NASA Astrophysics Data System (ADS)

Vincenti, Henri; Vay, Jean-Luc

2018-07-01

The advent of massively parallel supercomputers, with their distributed-memory technology using many processing units, has favored the development of highly-scalable local low-order solvers at the expense of harder-to-scale global very high-order spectral methods. Indeed, FFT-based methods, which were very popular on shared memory computers, have been largely replaced by finite-difference (FD) methods for the solution of many problems, including plasmas simulations with electromagnetic Particle-In-Cell methods. For some problems, such as the modeling of so-called "plasma mirrors" for the generation of high-energy particles and ultra-short radiations, we have shown that the inaccuracies of standard FD-based PIC methods prevent the modeling on present supercomputers at sufficient accuracy. We demonstrate here that a new method, based on the use of local FFTs, enables ultrahigh-order accuracy with unprecedented scalability, and thus for the first time the accurate modeling of plasma mirrors in 3D.

On the origin of cosmic magnetic fields

NASA Astrophysics Data System (ADS)

Kulsrud, Russell M.; Zweibel, Ellen G.

2008-04-01

We review the extensive and controversial literature concerning how the cosmic magnetic fields pervading nearly all galaxies and clusters of galaxies actually got started. Some observational evidence supports a hypothesis that the field is already moderately strong at the beginning of the life of a galaxy and its disc. One argument involves the chemical abundance of the light elements Be and B, while a second one is based on the detection of strong magnetic fields in very young high red shift galaxies. Since this problem of initial amplification of cosmic magnetic fields involves important plasma problems it is obvious that one must know the plasma in which the amplification occurs. Most of this review is devoted to this basic problem and for this it is necessary to devote ourselves to reviewing studies that take place in environments in which the plasma properties are most clearly understood. For this reason the authors have chosen to restrict themselves almost completely to studies of dynamos in our Galaxy. It is true that one can get a much better idea of the grand scope of galactic fields in extragalactic systems. However, most mature galaxies share the same dilemma as ours of overcoming important plasma problems. Since the authors are both trained in plasma physics we may be biased in pursuing this approach, but we feel it is justified by the above argument. In addition we feel we can produce a better review by staying close to that which we know best. In addition we have chosen not to consider the saturation problem of the galactic magnetic field since if the original dynamo amplification fails the saturation question does not arise. It is generally accepted that seed fields, whose strength is of order 10-20 G, easily spring up in the era preceding galaxy formation. Several mechanisms have been proposed to amplify these seed magnetic fields to a coherent structure with the microgauss strengths of the currently observed galactic magnetic fields. The standard and most popular mechanism is the α-Ω mean field dynamo theory developed by a number of people in the late sixties. This theory and its application to galactic magnetic fields is discussed in considerable detail in this review. We point out certain difficulties with this theory that make it seem unlikely that this is the whole story. The main difficulty with this as the only such amplification mechanism is rooted in the fact that, on galactic scales, flux is constant and is frozen in the interstellar medium. This implies that flux must be removed from the galactic discs, as is well recognized by the standard theory. For our Galaxy this turns out to be a major problem, since unless the flux and the interstellar mass are somehow separated, some interstellar mass must also be removed from the deep galactic gravitational well. This is very difficult. It is pointed out that unless the field has a substantial field strength, much larger than that of the seed fields, this separation can hardly happen. And of course, it must if the α-Ω dynamo is to start from the ultra weak seed field. (It is our philosophy, expressed in this review, that if an origin theory is unable to create the magnetic field in our Galaxy it is essentially incomplete.) Thus, it is more reasonable for the first and largest amplification to occur before the Galaxy forms, and the matter embedded in the field is gravitationally trapped. Two such mechanisms are discussed for such a pregalactic origin; (1) they are generated in the turbulence of the protogalaxy and (2) the fields come from giant radio jets. Several arguments against a primordial origin are also discussed, as are ways around them. Our conclusion as to the most likely origin of cosmic magnetic fields is that they are first produced at moderate field strengths by primordial mechanisms and then changed and their strength increased to their present value and structure by a galactic disc dynamo. The primordial mechanisms have not yet been seriously developed, and this preliminary amplification of the magnetic fields is still very open. If a convincing case can be made that these primordial mechanisms are necessary, more effort will of course be devoted to their study.

Plasma Liner Research for MTF at NASA Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Thio, Y. C. F.; Eskridge, R.; Lee, M.; Martin, A.; Smith, J.; Cassibry, J. T.; Wu, S. T.; Kirkpatrick, R. C.; Knapp, C. E.; Turchi, P. J.;

Self-consistent simulation of high-frequency driven plasma sheaths

NASA Astrophysics Data System (ADS)

Shihab, Mohammed; Eremin, Denis; Mussenbrock, Thomas; Brinkmann, Ralf

2011-10-01

Low pressure capacitively coupled plasmas are widely used in plasma processing and microelectronics industry. Understanding the dynamics of the boundary sheath is a fundamental problem. It controls the energy and angular distribution of ions bombarding the electrode, which in turn affects the surface reaction rate and the profile of microscopic features. In this contribution, we investigate the dynamics of plasma boundary sheaths by means of a kinetic self-consistent model, which is able to resolve the ion dynamics. Asymmetric sheath dynamics is observed for the intermediate RF regime, i.e., in the regime where the ion plasma frequency is equal to the driving frequency. The ion inertia causes an additional phase difference between the expansion and the contraction phase of the plasma sheath and an asymmetry for the ion energy distribution bimodal shape. A comparison with experimental results and particle in cell simulations is performed. Low pressure capacitively coupled plasmas are widely used in plasma processing and microelectronics industry. Understanding the dynamics of the boundary sheath is a fundamental problem. It controls the energy and angular distribution of ions bombarding the electrode, which in turn affects the surface reaction rate and the profile of microscopic features. In this contribution, we investigate the dynamics of plasma boundary sheaths by means of a kinetic self-consistent model, which is able to resolve the ion dynamics. Asymmetric sheath dynamics is observed for the intermediate RF regime, i.e., in the regime where the ion plasma frequency is equal to the driving frequency. The ion inertia causes an additional phase difference between the expansion and the contraction phase of the plasma sheath and an asymmetry for the ion energy distribution bimodal shape. A comparison with experimental results and particle in cell simulations is performed. The financial support from the Federal Ministry of Education and Research within the frame of the project ``Plasma-Technology-Grid'' and the support of the DFG via the collaborative research center SFB-TR87 is gratefully acknowledged.

System analysis of plasma centrifuges and sputtering

NASA Technical Reports Server (NTRS)

Hong, S. H.

1978-01-01

System analyses of cylindrical plasma centrifuges are presented, for which the velocity field and electromagnetic fields are calculated. The effects of different electrode geometrics, induced magnetic fields, Hall-effect, and secondary flows are discussed. It is shown that speeds of 10000 m/sec can be achieved in plasma centrifuges, and that an efficient separation of U238 and U235 in uranium plasmas is feasible. The external boundary-value problem for the deposition of sputtering products is reduced to a Fredholm integral equation, which is solved analytically by means of the method of successive approximations.

Drift kinetic effects on plasma response in high beta spherical tokamak experiments

NASA Astrophysics Data System (ADS)

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.; Liu, Yueqiang; Kaye, Stanley M.; Gerhardt, Stefan

2018-01-01

The high β plasma response to rotating n=1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit (Troyon et al 1984 Plasma Phys. Control. Fusion 26 209). Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppresses the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. The complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.

Object-oriented code SUR for plasma kinetic simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levchenko, V.D.; Sigov, Y.S.

1995-12-31

We have developed a self-consistent simulation code based on object-oriented model of plasma (OOMP) for solving the Vlasov/Poisson (V/P), Vlasov/Maxwell (V/M), Bhatnagar-Gross-Krook (BGK) as well as Fokker-Planck (FP) kinetic equations. The application of an object-oriented approach (OOA) to simulation of plasmas and plasma-like media by means of splitting methods permits to uniformly describe and solve the wide circle of plasma kinetics problems, including those being very complicated: many-dimensional, relativistic, with regard for collisions, specific boundary conditions etc. This paper gives the brief description of possibilities of the SUR code, as a concrete realization of OOMP.

Metal surface nitriding by laser induced plasma

NASA Astrophysics Data System (ADS)

Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

1996-10-01

We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features as purity, thickness, and surface morphology.

Developing the Polynomial Expressions for Fields in the ITER Tokamak

NASA Astrophysics Data System (ADS)

Sharma, Stephen

2017-10-01

The two most important problems to be solved in the development of working nuclear fusion power plants are: sustained partial ignition and turbulence. These two phenomena are the subject of research and investigation through the development of analytic functions and computational models. Ansatz development through Gaussian wave-function approximations, dielectric quark models, field solutions using new elliptic functions, and better descriptions of the polynomials of the superconducting current loops are the critical theoretical developments that need to be improved. Euler-Lagrange equations of motion in addition to geodesic formulations generate the particle model which should correspond to the Dirac dispersive scattering coefficient calculations and the fluid plasma model. Feynman-Hellman formalism and Heaviside step functional forms are introduced to the fusion equations to produce simple expressions for the kinetic energy and loop currents. Conclusively, a polynomial description of the current loops, the Biot-Savart field, and the Lagrangian must be uncovered before there can be an adequate computational and iterative model of the thermonuclear plasma.

Expressions for Fields in the ITER Tokamak

NASA Astrophysics Data System (ADS)

Sharma, Stephen

2017-10-01

The two most important problems to be solved in the development of working nuclear fusion power plants are: sustained partial ignition and turbulence. These two phenomenon are the subject of research and investigation through the development of analytic functions and computational models. Ansatz development through Gaussian wave-function approximations, dielectric quark models, field solutions using new elliptic functions, and better descriptions of the polynomials of the superconducting current loops are the critical theoretical developments that need to be improved. Euler-Lagrange equations of motion in addition to geodesic formulations generate the particle model which should correspond to the Dirac dispersive scattering coefficient calculations and the fluid plasma model. Feynman-Hellman formalism and Heaviside step functional forms are introduced to the fusion equations to produce simple expressions for the kinetic energy and loop currents. Conclusively, a polynomial description of the current loops, the Biot-Savart field, and the Lagrangian must be uncovered before there can be an adequate computational and iterative model of the thermonuclear plasma.

Development of a new virtual diagnostic for V3FIT

NASA Astrophysics Data System (ADS)

Trevisan, G. L.; Cianciosa, M. R.; Terranova, D.; Hanson, J. D.

2014-12-01

The determination of plasma equilibria from diagnostic information is a fundamental issue. V3FIT is a fully three-dimensional reconstruction code capable of solving the inverse problem using both magnetic and kinetic measurements. It uses VMEC as core equilibrium solver and supports both free- and fixed-boundary reconstruction approaches. In fixed-boundary mode VMEC does not use explicit information about currents in external coils, even though it has important effects on the shape of the safety factor profile. Indeed, the edge safety factor influences the reversal position in RFP plasmas, which then determines the position of the m = 0 island chain and the edge transport properties. In order to exploit such information a new virtual diagnostic has been developed, that thanks to Ampère's law relates the external current through the center of the torus to the circulation of the toroidal magnetic field on the outermost flux surface. The reconstructions that exploit the new diagnostic are indeed found to better interpret the experimental data with respect to edge physics.

Antimicrobial cotton textiles with robust superhydrophobicity via plasma for oily water separation

NASA Astrophysics Data System (ADS)

Zhang, Ming; Pang, Jiuyin; Bao, Wenhui; Zhang, Wenbo; Gao, He; Wang, Chengyu; Shi, Junyou; Li, Jian

2017-10-01

During these decades, functional materials are facing the severe challenge of their weak surface structure. To solve this problem, plasma technology and spraying technology were utilized to improve the bonding effect between cotton substrates and coating structures. Herein, silica/silver nanoparticles (SiO2/Ag NPs) were prepared and introduced to the nano-/micro- structures on sample surface by spraying technology in the existence of polyurethane adhesive. Then the circles of spraying procedure containing adhesive and SiO2/Ag NPs had been discussed. After further fluorination, the samples still displayed an excellent waterproof property even after abrasion test with sand paper and various washing test by its solvent-acetone or harsh liquids with strong acidity/alkalinity, indicating their robust surfaces structures. More importantly, this product displayed the outstanding performance no matter in laboratory oil/water filtration or the extensive oil leakage and spill. At last, our modification also endowed the cotton sample with great antimicrobial property.

The simulation of the geosynchronous Earth orbit plasma environment in Chamber A: An assessment of possible experimental investigations

NASA Technical Reports Server (NTRS)

Bernstein, W.

1981-01-01

The possible use of Chamber A for the replication or simulation of space plasma physics processes which occur in the geosynchronous Earth orbit (GEO) environment is considered. It is shown that replication is not possible and that scaling of the environmental conditions is required for study of the important instability processes. Rules for such experimental scaling are given. At the present time, it does not appear technologically feasible to satisfy these requirements in Chamber A. It is, however, possible to study and qualitatively evaluate the problem of vehicle charging at GEO. In particular, Chamber A is sufficiently large that a complete operational spacecraft could be irradiated by beams and charged to high potentials. Such testing would contribute to the assessment of the operational malfunctions expected at GEO and their possible correction. However, because of the many tabulated limitations in such a testing programs, its direct relevance to conditions expected in the geo environment remains questionable.

Anisotropic Thermal Diffusion

NASA Astrophysics Data System (ADS)

Gardiner, Thomas

2013-10-01

Anisotropic thermal diffusion in magnetized plasmas is an important physical phenomena for a diverse set of physical conditions ranging from astrophysical plasmas to MFE and ICF. Yet numerically simulating this phenomenon accurately poses significant challenges when the computational mesh is misaligned with respect to the magnetic field. Particularly when the temperature gradients are unresolved, one frequently finds entropy violating solutions with heat flowing from cold to hot zones for χ∥ /χ⊥ >=102 which is substantially smaller than the range of interest which can reach 1010 or higher. In this talk we present a new implicit algorithm for solving the anisotropic thermal diffusion equations and demonstrate its characteristics on what has become a fairly standard set of test problems in the literature. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2013-5687A.

Evolving paradigms for desensitization in managing broadly HLA sensitized transplant candidates.

PubMed

Reinsmoen, Nancy L; Lai, Chi-Hung; Vo, Ashley; Jordan, Stanley C

2012-04-01

The broadly human leukocyte antigen (HLA) sensitized patient awaiting organ transplantation remains a persistent and significant problem for transplant medicine. Sensitization occurs as a consequence of exposure to HLA antigens through pregnancy, blood and platelet transfusions, and previous transplants. Early experience with desensitization protocols coupled with improved diagnostics for donor-specific antibodies (DSAs) and renal pathology have greatly improved transplant rates and outcomes for patients once considered un-transplantable or at high risk for poor outcomes. More recent advances have occurred through implementation of a national allocation system requiring the entering of unacceptable antigens that reduces the rate of crossmatch positivity. Current desensitization therapies include high-dose intravenous immunoglobulin (IVIG), plasma exchange (PLEX) with low-dose IVIG, and IVIG combined with rituximab. Developing therapies include proteasome inhibitors aimed at plasma cells and modifiers of complement-mediated injury. Here we discuss the important advancements in desensitization including defining the risk for antibody-mediated rejection prior to transplantation and the evolution of therapies aimed at reducing the impact of antibody injury on allografts.

Interaction of Intense Lasers with Plasmas

NASA Astrophysics Data System (ADS)

Shvets, Gennady

1995-01-01

This thesis addresses two important topics in nonlinear laser plasma physics: the interaction of intense lasers with a non thermal homogeneous plasma, the excitation of laser wakefields in hollow plasma channels, and the stability of channel guided propagation of laser pulses. In the first half of this thesis a new theoretical approach to the nonlinear interaction of intense laser pulses with underdense plasmas is developed. Unlike previous treatments, this theory is three-dimensional, relativistically covariant, and does not assume that a<<1, where a=eA/mc^2 is a dimensionless vector potential. This formalism borrows the diagrammatic techniques from quantum field theory, yet remains classical. This classical field theory, which treats cold plasma as a relativistic field interacting with the electromagnetic fields, introduces an artificial length scale which is smaller than any physically relevant spatial scale. By adopting a special (Arnowitt -Fickler) gauge, electromagnetic waves in a cold relativistic plasma are separated into "photons" and "plasmons" which are the relativistic extensions of electrostatic and electromagnetic waves in a cold stationary plasma. The field-theoretical formalism is applied to a variety of nonlinear problems including harmonic generation, parametric instabilities, and nonlinear corrections to the index of refraction. For the first time the rate of the second harmonic emission from a homogeneous plasma is calculated and its dependence on the polarization of the incident radiation is studied. An experimental check of this calculation is suggested, based on the predicted non-linear polarization rotation (the second harmonic is emitted polarized perpendicularly to polarization of the incident signal). The concept of renormalization is applied to the plasma and electromagnetic radiation (photons and plasmons). To the lowest order, this corresponds to relativistically correcting the electron mass for its oscillation in an intense EM field and to replacing the vacuum dispersion relation by the usual relativistic plasma dispersion relation. This renormalization procedure is then carried to higher order in epsilon=omega_sp{p} {2}a^2/[(1+a^2/2)^ {3/2}omega^2]. This yields the nonlinear modification of the index of refraction of a strong electromagnetic wave and the dispersion of a weak probe in the presence of the wave. In the second part of this thesis the stability of short laser pulses propagating through parabolic channels and the wake excitation of hollow plasma channels are studied. The stability of a channel guided short laser pulse propagation is analyzed for the first time. Perturbations to the laser pulse are shown to modify the ponderomotive pressure, which distorts the dielectric properties of the plasma channel. The channel perturbation then further distorts the laser pulse. A set of coupled mode equations is derived, and a matrix dispersion relation is obtained analytically. The ponderomotive excitation of wakefields in a hollow plasma channel by an intense laser pulse is studied analytically. An important finding is that the resonant absorption in the channel wall dissipates the accelerating wake, thereby introducing a finite quality factor of the hollow plasma channel and reducing the number of electron bunches that can be accelerated in the wake of a single laser pulse. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.) (Abstract shortened by UMI.).

Dynamic Response of a Magnetized Plasma to AN External Source: Application to Space and Solid State Plasmas

NASA Astrophysics Data System (ADS)

Zhou, Huai-Bei

This dissertation examines the dynamic response of a magnetoplasma to an external time-dependent current source. To achieve this goal a new method which combines analytic and numerical techniques to study the dynamic response of a 3-D magnetoplasma to a time-dependent current source imposed across the magnetic field was developed. The set of the cold electron and/or ion plasma equations and Maxwell's equations are first solved analytically in (k, omega)^ace; inverse Laplace and 3 -D complex Fast Fourier Transform (FFT) techniques are subsequently used to numerically transform the radiation fields and plasma currents from the (k, omega) ^ace to the (r, t) space. The dynamic responses of the electron plasma and of the compensated two-component plasma to external current sources are studied separately. The results show that the electron plasma responds to a time -varying current source imposed across the magnetic field by exciting whistler/helicon waves and forming of an expanding local current loop, induced by field aligned plasma currents. The current loop consists of two anti-parallel field-aligned current channels concentrated at the ends of the imposed current and a cross-field current region connecting these channels. The latter is driven by an electron Hall drift. A compensated two-component plasma responds to the same current source as following: (a) For slow time scales tau > Omega_sp{i}{-1} , it generates Alfven waves and forms a non-local current loop in which the ion polarization currents dominate the cross-field current; (b) For fast time scales tau < Omega_sp{i}{-1} , the dynamic response of the compensated two-component plasma is the same as that of the electron plasma. The characteristics of the current closure region are determined by the background plasma density, the magnetic field and the time scale of the current source. This study has applications to a diverse range of space and solid state plasma problems. These problems include current closure in emf inducing tethered satellite systems (TSS), generation of ELF/VLF waves by ionospheric heating, current closure and quasineutrality in thin magnetopause transitions, and short electromagnetic pulse generation in solid state plasmas. The cross-field current in TSS builds up on a time scale corresponding to the whistler waves and results in local current closure. Amplitude modulated HF ionospheric heating generates ELF/VLF waves by forming a horizontal magnetic dipole. The dipole is formed by the current closure in the modified region. For thin transition the time-dependent cross-field polarization field at the magnetopause could be neutralized by the formation of field aligned current loops that close by a cross-field electron Hall current. A moving current source in a solid state plasma results in microwave emission if the speed of the source exceeds the local phase velocity of the helicon or Alfven waves. Detailed analysis of the above problems is presented in the thesis.

Method for fabricating beryllium structures

DOEpatents

Hovis, Jr., Victor M.; Northcutt, Jr., Walter G.

1977-01-01

Thin-walled beryllium structures are prepared by plasma spraying a mixture of beryllium powder and about 2500 to 4000 ppm silicon powder onto a suitable substrate, removing the plasma-sprayed body from the substrate and placing it in a sizing die having a coefficient of thermal expansion similar to that of the beryllium, exposing the plasma-sprayed body to a moist atmosphere, outgassing the plasma-sprayed body, and then sintering the plasma-sprayed body in an inert atmosphere to form a dense, low-porosity beryllium structure of the desired thin-wall configuration. The addition of the silicon and the exposure of the plasma-sprayed body to the moist atmosphere greatly facilitate the preparation of the beryllium structure while minimizing the heretofore deleterious problems due to grain growth and grain orientation.

Electromagnetic fluctuation spectra of collective oscillations in magnetized Maxwellian equal mass plasmas for low-frequency waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vafin, S.; Schlickeiser, R.; Yoon, P. H.

Recently, the general electromagnetic fluctuation theory for magnetized plasmas has been used to study the steady-state fluctuation spectra and the total intensity of low-frequency collective weakly damped modes for parallel wave vectors in Maxwellian plasmas. Now, we address the same question with respect to an arbitrary direction of the wave-vector. Here, we analyze this problem for equal mass plasmas. These plasmas are a very good tool to study various plasma phenomena, as they considerably facilitate the theoretical consideration and at the same time provide with their clear physical picture. Finally, we compare our results in the limiting case of parallelmore » wave vectors with the previous study.« less

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Spectral and temporal characteristics of a laser plasma

NASA Astrophysics Data System (ADS)

Lipchak, A. I.; Solomonov, V. I.; Tel'nov, V. A.; Osipov, V. V.

1995-04-01

An experimental investigation was made of the spectral and temporal characteristics of a laser plasma formed by the interaction of a CO2 laser pulse with a target in atmospheric air. The results obtained indicate that the main role in the process of filling the excited states in a laser plasma is played by a recombination cascade and that both atoms and molecules of the atmospheric gases are excited. The result also show that a laser plasma can be used in spectroscopic analysis of multicomponent samples. The solution of the thermophysical problem of heating of a target by laser radiation supports the existing ideas on the process of formation of a plasma near the target surface in air.

Drift kinetic effects on the plasma response in high beta spherical tokamak experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.

The high β plasma response to rotating n = 1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit. Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppressesmore » the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. In conclusion, the complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.« less

Drift kinetic effects on the plasma response in high beta spherical tokamak experiments

DOE PAGES

Wang, Zhirui; Park, Jong-Kyu; Menard, Jonathan E.; ...

2017-09-21

The high β plasma response to rotating n = 1 external magnetic perturbations is numerically studied and compared with the National Spherical Torus Experiment (NSTX). The hybrid magnetohydrodynamic(MHD)-kinetic modeling shows that drift kinetic effects are important in resolving the disagreement of plasma response between the ideal MHD prediction and the NSTX experimental observation when plasma pressure reaches and exceeds the no-wall limit. Since the external rotating fields and high plasma rotation are presented in the NSTX experiments, the importance of the resistive wall effect and plasma rotation in determining the plasma response is also identified, where the resistive wall suppressesmore » the plasma response through the wall eddy current. The inertial energy due to plasma rotation destabilizes the plasma. In conclusion, the complexity of the plasma response in this study indicates that MHD modeling, including comprehensive physics, e.g. the drift kinetic effects, resistive wall and plasma rotation, are essential in order to reliably predict the plasma behavior in a high beta spherical tokamak device.« less

A Riccati solution for the ideal MHD plasma response with applications to real-time stability control

NASA Astrophysics Data System (ADS)

Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.

2018-03-01

Active feedback control of ideal MHD stability in a tokamak requires rapid plasma stability analysis. Toward this end, we reformulate the δW stability method with a Hamilton-Jacobi theory, elucidating analytical and numerical features of the generic tokamak ideal MHD stability problem. The plasma response matrix is demonstrated to be the solution of an ideal MHD matrix Riccati differential equation. Since Riccati equations are prevalent in the control theory literature, such a shift in perspective brings to bear a range of numerical methods that are well-suited to the robust, fast solution of control problems. We discuss the usefulness of Riccati techniques in solving the stiff ordinary differential equations often encountered in ideal MHD stability analyses—for example, in tokamak edge and stellarator physics. We demonstrate the applicability of such methods to an existing 2D ideal MHD stability code—DCON [A. H. Glasser, Phys. Plasmas 23, 072505 (2016)]—enabling its parallel operation in near real-time, with wall-clock time ≪1 s . Such speed may help enable active feedback ideal MHD stability control, especially in tokamak plasmas whose ideal MHD equilibria evolve with inductive timescale τ≳ 1s—as in ITER.

A parallelization method for time periodic steady state in simulation of radio frequency sheath dynamics

NASA Astrophysics Data System (ADS)

Kwon, Deuk-Chul; Shin, Sung-Sik; Yu, Dong-Hun

2017-10-01

In order to reduce the computing time in simulation of radio frequency (rf) plasma sources, various numerical schemes were developed. It is well known that the upwind, exponential, and power-law schemes can efficiently overcome the limitation on the grid size for fluid transport simulations of high density plasma discharges. Also, the semi-implicit method is a well-known numerical scheme to overcome on the simulation time step. However, despite remarkable advances in numerical techniques and computing power over the last few decades, efficient multi-dimensional modeling of low temperature plasma discharges has remained a considerable challenge. In particular, there was a difficulty on parallelization in time for the time periodic steady state problems such as capacitively coupled plasma discharges and rf sheath dynamics because values of plasma parameters in previous time step are used to calculate new values each time step. Therefore, we present a parallelization method for the time periodic steady state problems by using period-slices. In order to evaluate the efficiency of the developed method, one-dimensional fluid simulations are conducted for describing rf sheath dynamics. The result shows that speedup can be achieved by using a multithreading method.

Removal of DLC film on polymeric materials by low temperature atmospheric-pressure plasma jet

NASA Astrophysics Data System (ADS)

Kobayashi, Daichi; Tanaka, Fumiyuki; Kasai, Yoshiyuki; Sahara, Junki; Asai, Tomohiko; Hiratsuka, Masanori; Takatsu, Mikio; Koguchi, Haruhisa

2017-10-01

Diamond-like carbon (DLC) thin film has various excellent functions. For example, high hardness, abrasion resistance, biocompatibility, etc. Because of these functionalities, DLC has been applied in various fields. Removal method of DLC has also been developed for purpose of microfabrication, recycling the substrate and so on. Oxygen plasma etching and shot-blast are most common method to remove DLC. However, the residual carbon, high cost, and damage onto the substrate are problems to be solved for further application. In order to solve these problems, removal method using low temperature atmospheric pressure plasma jet has been developed in this work. The removal effect of this method has been demonstrated for DLC on the SUS304 substrate. The principle of this method is considered that oxygen radical generated by plasma oxidize carbon constituting the DLC film and then the film is removed. In this study, in order to widen application range of this method and to understand the mechanism of film removal, plasma irradiation experiment has been attempted on DLC on the substrate with low heat resistance. The DLC was removed successfully without any significant thermal damage on the surface of polymeric material.

Physics-Based Computational Algorithm for the Multi-Fluid Plasma Model

DTIC Science & Technology

2014-06-30

applying it to study laser - 20 Physics-Based Multi-Fluid Plasma Algorithm Shumlak Figure 6: Blended finite element method applied to the species...separation problem in capsule implosions. Number densities and electric field are shown after the laser drive has compressed the multi-fluid plasma and...6 after the laser drive has started the compression. A separation clearly develops. The solution is found using an explicit advance (CFL=1) for the

Waves and Instabilities in Steady-State High-Beta Plasmas

DTIC Science & Technology

1976-07-01

us working on magnetospheric related problems. Several groups are now constructing identical devices including Y. Nishida of Utsunomiya University...and other satellites operate in the magnetospheric plasma environment at the geosynchronous orbit (%6.6 earth radii). Arc- related deterioration of the...carefully 16 - 3diagnosed device produces a plasma of density n 3 x 10 cm and temperature Te = Ti W 1.6eV. (3) Heat Flow Measurements in a Laser-Heated

The design and development of a space laboratory to conduct magnetospheric and plasma research

NASA Technical Reports Server (NTRS)

Rosen, A.

1974-01-01

A design study was conducted concerning a proposed shuttle-borne space laboratory for research on magnetospheric and plasma physics. A worldwide survey found two broad research disciplines of interest: geophysical studies of the dynamics and structure of the magnetosphere (including wave characteristics, wave-particle interactions, magnetospheric modifications, beam-plasma interactions, and energetic particles and tracers) and plasma physics studies (plasma physics in space, wake and sheath studies, and propulsion and devices). The Plasma Physics and Environmental Perturbation Laboratory (PPEPL) designed to perform experiments in these areas will include two 50-m booms and two maneuverable subsatellites, a photometer array, standardized proton, electron, and plasma accelerators, a high-powered transmitter for frequencies above 100 kHz, a low-power transmitter for VLF and below, and complete diagnostic packages. Problem areas in the design of a space plasma physics laboratory are indicated.

Quantitative methods and detection techniques in hyperspectral imaging involving medical and other applications

NASA Astrophysics Data System (ADS)

Roy, Ankita

2007-12-01

This research using Hyperspectral imaging involves recognizing targets through spatial and spectral matching and spectral un-mixing of data ranging from remote sensing to medical imaging kernels for clinical studies based on Hyperspectral data-sets generated using the VFTHSI [Visible Fourier Transform Hyperspectral Imager], whose high resolution Si detector makes the analysis achievable. The research may be broadly classified into (I) A Physically Motivated Correlation Formalism (PMCF), which places both spatial and spectral data on an equivalent mathematical footing in the context of a specific Kernel and (II) An application in RF plasma specie detection during carbon nanotube growing process. (III) Hyperspectral analysis for assessing density and distribution of retinopathies like age related macular degeneration (ARMD) and error estimation enabling the early recognition of ARMD, which is treated as an ill-conditioned inverse imaging problem. The broad statistical scopes of this research are two fold-target recognition problems and spectral unmixing problems. All processes involve experimental and computational analysis of Hyperspectral data sets is presented, which is based on the principle of a Sagnac Interferometer, calibrated to obtain high SNR levels. PMCF computes spectral/spatial/cross moments and answers the question of how optimally the entire hypercube should be sampled and finds how many spatial-spectral pixels are required precisely for a particular target recognition. Spectral analysis of RF plasma radicals, typically Methane plasma and Argon plasma using VFTHSI has enabled better process monitoring during growth of vertically aligned multi-walled carbon nanotubes by instant registration of the chemical composition or density changes temporally, which is key since a significant correlation can be found between plasma state and structural properties. A vital focus of this dissertation is towards medical Hyperspectral imaging applied to retinopathies like age related macular degeneration targets taken with a Fundus imager, which is akin to the VFTHSI. Detection of the constituent components in the diseased hyper-pigmentation area is also computed. The target or reflectance matrix is treated as a highly ill-conditioned spectral un-mixing problem, to which methodologies like inverse techniques, principal component analysis (PCA) and receiver operating curves (ROC) for precise spectral recognition of infected area. The region containing ARMD was easily distinguishable from the spectral mesh plots over the entire band-pass area. Once the location was detected the PMCF coefficients were calculated by cross correlating a target of normal oxygenated retina with the deoxygenated one. The ROCs generated using PMCF shows 30% higher detection probability with improved accuracy than ROCs based on Spectral Angle Mapper (SAM). By spectral unmixing methods, the important endmembers/carotenoids of the MD pigment were found to be Xanthophyl and lutein, while beta-carotene which showed a negative correlation in the unconstrained inverse problem is a supplement given to ARMD patients to prevent the disease and does not occur in the eye. Literature also shows degeneration of meso-zeaxanthin. Ophthalmologists may assert the presence of ARMD and commence the diagnosis process if the Xanthophyl pigment have degenerated 89.9%, while the lutein has decayed almost 80%, as found deduced computationally. This piece of current research takes it to the next level of precise investigation in the continuing process of improved clinical findings by correlating the microanatomy of the diseased fovea and shows promise of an early detection of this disease.

"Magnetic Reconnection Code: Applications to Sawtooth Oscillations, Error-Field Induced Islands, and the Dynamo Effect" - Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fitzpatrick, Richard

2007-09-24

Dr. Fitzpatrick has written an MHD code in order to investigate the interaction of tearing modes with flow and external magnetic perturbations, which has been successfully benchmarked against both linear and nonlinear theory and used to investigate error-field penetration in flowing plasmas. The same code was used to investigate the so-called Taylor problem. He employed the University of Chicago's FLASH code to further investigate the Taylor problem, discovering a new aspect of the problem. Dr. Fitzpatrick has written a 2-D Hall MHD code and used it to investigate the collisionless Taylor problem. Dr. Waelbroeck has performed an investigation of themore » scaling of the error-field penetration threshold in collisionless plasmas. Paul Watson and Dr. Fitzpatrick have written a fully-implicit extended-MHD code using the PETSC framework. Five publications have resulted from this grant work.« less

Problem of Auroral Oval Mapping and Multiscale Auroral Structures

NASA Astrophysics Data System (ADS)

Antonova, Elizaveta; Stepanova, Marina; Kirpichev, Igor; Vovchenko, Vadim; Vorobjev, Viachislav; Yagodkina, Oksana

The problem of the auroral oval mapping to the equatorial plane is reanalyzed taking into account the latest results of the analysis of plasma pressure distribution at low altitudes and at the equatorial plane. Statistical pictures of pressure distribution at low latitudes are obtained using data of DMSP observations. We obtain the statistical pictures of pressure distribution at the equatorial plane using data of THEMIS mission. Results of THEMIS observations demonstrate the existence of plasma ring surrounding the Earth at geocentric distances from ~6 till ~12Re. Plasma pressure in the ring is near to isotropic and its averaged values are larger than 0.2 nPa. We take into account that isotropic plasma pressure is constant along the field line and that the existence of field-aligned potential drops in the region of the acceleration of auroral electrons leads to pressure decrease at low altitudes. We show that most part of quite time auroral oval does not map to the real plasma sheet. It maps to the surrounding the Earth plasma ring. We also show that transverse currents in the plasma ring are closed inside the magnetosphere forming the high latitude continuation of the ordinary ring current. The obtained results are used for the explanation of ring like form of the auroral oval. We also analyze the processes of the formation of multiscale auroral structures including thin auroral arcs and discuss the difficulties of the theories of alfvenic acceleration of auroral electrons.

Fully Parallel MHD Stability Analysis Tool

NASA Astrophysics Data System (ADS)

Svidzinski, Vladimir; Galkin, Sergei; Kim, Jin-Soo; Liu, Yueqiang

2014-10-01

Progress on full parallelization of the plasma stability code MARS will be reported. MARS calculates eigenmodes in 2D axisymmetric toroidal equilibria in MHD-kinetic plasma models. It is a powerful tool for studying MHD and MHD-kinetic instabilities and it is widely used by fusion community. Parallel version of MARS is intended for simulations on local parallel clusters. It will be an efficient tool for simulation of MHD instabilities with low, intermediate and high toroidal mode numbers within both fluid and kinetic plasma models, already implemented in MARS. Parallelization of the code includes parallelization of the construction of the matrix for the eigenvalue problem and parallelization of the inverse iterations algorithm, implemented in MARS for the solution of the formulated eigenvalue problem. Construction of the matrix is parallelized by distributing the load among processors assigned to different magnetic surfaces. Parallelization of the solution of the eigenvalue problem is made by repeating steps of the present MARS algorithm using parallel libraries and procedures. Initial results of the code parallelization will be reported. Work is supported by the U.S. DOE SBIR program.

Status and problems of fusion reactor development.

PubMed

Schumacher, U

2001-03-01

Thermonuclear fusion of deuterium and tritium constitutes an enormous potential for a safe, environmentally compatible and sustainable energy supply. The fuel source is practically inexhaustible. Further, the safety prospects of a fusion reactor are quite favourable due to the inherently self-limiting fusion process, the limited radiologic toxicity and the passive cooling property. Among a small number of approaches, the concept of toroidal magnetic confinement of fusion plasmas has achieved most impressive scientific and technical progress towards energy release by thermonuclear burn of deuterium-tritium fuels. The status of thermonuclear fusion research activity world-wide is reviewed and present solutions to the complicated physical and technological problems are presented. These problems comprise plasma heating, confinement and exhaust of energy and particles, plasma stability, alpha particle heating, fusion reactor materials, reactor safety and environmental compatibility. The results and the high scientific level of this international research activity provide a sound basis for the realisation of the International Thermonuclear Experimental Reactor (ITER), whose goal is to demonstrate the scientific and technological feasibility of a fusion energy source for peaceful purposes.

Thermonuclear land of plenty

NASA Astrophysics Data System (ADS)

Gasior, P.

2014-11-01

Since the process of energy production in the stars has been identified as the thermonuclear fusion, this mechanism has been proclaimed as a future, extremely modern, reliable and safe for sustaining energetic needs of the humankind. However, the idea itself was rather straightforward and the first attempts to harness thermonuclear reactions have been taken yet in 40s of the twentieth century, it quickly appeared that physical and technical problems of domesticating exotic high temperature medium known as plasma are far from being trivial. Though technical developments as lasers, superconductors or advanced semiconductor electronics and computers gave significant contribution for the development of the thermonuclear fusion reactors, for a very long time their efficient performance was out of reach of technology. Years of the scientific progress brought the conclusions that for the development of the thermonuclear power plants an enormous interdisciplinary effort is needed in many fields of science covering not only plasma physics but also material research, superconductors, lasers, advanced diagnostic systems (e.g. spectroscopy, interferometry, scattering techniques, etc.) with huge amounts of data to be processed, cryogenics, measurement-control systems, automatics, robotics, nanotechnology, etc. Due to the sophistication of the problems with plasma control and plasma material interactions only such a combination of the research effort can give a positive output which can assure the energy needs of our civilization. In this paper the problems of thermonuclear technology are briefly outlined and it is shown why this domain can be a broad field for the experts dealing with electronics, optoelectronics, programming and numerical simulations, who at first glance can have nothing common with the plasma or nuclear physics.

A prospectus on kinetic heliophysics

NASA Astrophysics Data System (ADS)

Howes, Gregory G.

2017-05-01

Under the low density and high temperature conditions typical of heliospheric plasmas, the macroscopic evolution of the heliosphere is strongly affected by the kinetic plasma physics governing fundamental microphysical mechanisms. Kinetic turbulence, collisionless magnetic reconnection, particle acceleration, and kinetic instabilities are four poorly understood, grand-challenge problems that lie at the new frontier of kinetic heliophysics. The increasing availability of high cadence and high phase-space resolution measurements of particle velocity distributions by current and upcoming spacecraft missions and of massively parallel nonlinear kinetic simulations of weakly collisional heliospheric plasmas provides the opportunity to transform our understanding of these kinetic mechanisms through the full utilization of the information contained in the particle velocity distributions. Several major considerations for future investigations of kinetic heliophysics are examined. Turbulent dissipation followed by particle heating is highlighted as an inherently two-step process in weakly collisional plasmas, distinct from the more familiar case in fluid theory. Concerted efforts must be made to tackle the big-data challenge of visualizing the high-dimensional (3D-3V) phase space of kinetic plasma theory through physics-based reductions. Furthermore, the development of innovative analysis methods that utilize full velocity-space measurements, such as the field-particle correlation technique, will enable us to gain deeper insight into these four grand-challenge problems of kinetic heliophysics. A systems approach to tackle the multi-scale problem of heliophysics through a rigorous connection between the kinetic physics at microscales and the self-consistent evolution of the heliosphere at macroscales will propel the field of kinetic heliophysics into the future.

A prospectus on kinetic heliophysics

PubMed Central

2017-01-01

Under the low density and high temperature conditions typical of heliospheric plasmas, the macroscopic evolution of the heliosphere is strongly affected by the kinetic plasma physics governing fundamental microphysical mechanisms. Kinetic turbulence, collisionless magnetic reconnection, particle acceleration, and kinetic instabilities are four poorly understood, grand-challenge problems that lie at the new frontier of kinetic heliophysics. The increasing availability of high cadence and high phase-space resolution measurements of particle velocity distributions by current and upcoming spacecraft missions and of massively parallel nonlinear kinetic simulations of weakly collisional heliospheric plasmas provides the opportunity to transform our understanding of these kinetic mechanisms through the full utilization of the information contained in the particle velocity distributions. Several major considerations for future investigations of kinetic heliophysics are examined. Turbulent dissipation followed by particle heating is highlighted as an inherently two-step process in weakly collisional plasmas, distinct from the more familiar case in fluid theory. Concerted efforts must be made to tackle the big-data challenge of visualizing the high-dimensional (3D-3V) phase space of kinetic plasma theory through physics-based reductions. Furthermore, the development of innovative analysis methods that utilize full velocity-space measurements, such as the field-particle correlation technique, will enable us to gain deeper insight into these four grand-challenge problems of kinetic heliophysics. A systems approach to tackle the multi-scale problem of heliophysics through a rigorous connection between the kinetic physics at microscales and the self-consistent evolution of the heliosphere at macroscales will propel the field of kinetic heliophysics into the future. PMID:29104421

Simulating Coupling Complexity in Space Plasmas: First Results from a new code

NASA Astrophysics Data System (ADS)

Kryukov, I.; Zank, G. P.; Pogorelov, N. V.; Raeder, J.; Ciardo, G.; Florinski, V. A.; Heerikhuisen, J.; Li, G.; Petrini, F.; Shematovich, V. I.; Winske, D.; Shaikh, D.; Webb, G. M.; Yee, H. M.

2005-12-01

The development of codes that embrace 'coupling complexity' via the self-consistent incorporation of multiple physical scales and multiple physical processes in models has been identified by the NRC Decadal Survey in Solar and Space Physics as a crucial necessary development in simulation/modeling technology for the coming decade. The National Science Foundation, through its Information Technology Research (ITR) Program, is supporting our efforts to develop a new class of computational code for plasmas and neutral gases that integrates multiple scales and multiple physical processes and descriptions. We are developing a highly modular, parallelized, scalable code that incorporates multiple scales by synthesizing 3 simulation technologies: 1) Computational fluid dynamics (hydrodynamics or magneto-hydrodynamics-MHD) for the large-scale plasma; 2) direct Monte Carlo simulation of atoms/neutral gas, and 3) transport code solvers to model highly energetic particle distributions. We are constructing the code so that a fourth simulation technology, hybrid simulations for microscale structures and particle distributions, can be incorporated in future work, but for the present, this aspect will be addressed at a test-particle level. This synthesis we will provide a computational tool that will advance our understanding of the physics of neutral and charged gases enormously. Besides making major advances in basic plasma physics and neutral gas problems, this project will address 3 Grand Challenge space physics problems that reflect our research interests: 1) To develop a temporal global heliospheric model which includes the interaction of solar and interstellar plasma with neutral populations (hydrogen, helium, etc., and dust), test-particle kinetic pickup ion acceleration at the termination shock, anomalous cosmic ray production, interaction with galactic cosmic rays, while incorporating the time variability of the solar wind and the solar cycle. 2) To develop a coronal mass ejection and interplanetary shock propagation model for the inner and outer heliosphere, including, at a test-particle level, wave-particle interactions and particle acceleration at traveling shock waves and compression regions. 3) To develop an advanced Geospace General Circulation Model (GGCM) capable of realistically modeling space weather events, in particular the interaction with CMEs and geomagnetic storms. Furthermore, by implementing scalable run-time supports and sophisticated off- and on-line prediction algorithms, we anticipate important advances in the development of automatic and intelligent system software to optimize a wide variety of 'embedded' computations on parallel computers. Finally, public domain MHD and hydrodynamic codes had a transforming effect on space and astrophysics. We expect that our new generation, open source, public domain multi-scale code will have a similar transformational effect in a variety of disciplines, opening up new classes of problems to physicists and engineers alike.

[Historical changes in the list of plasma fractionation products placed on the WHO Model List of Essential Medicines].

PubMed

Sakagami, Yuichiro; Tsutani, Kiichiro

2014-01-01

The purpose of this study was to summarize the historical changes in the list of plasma fractionation products (PFP) placed on the Model List of Essential Medicines (EML) issued by the World Health Organization (WHO). PFP such as albumin, blood coagulation factors, and immunoglobulins are derived from blood collected from thousands of people. PFP have been listed since the first edition of the EML (1977). However, the PFP listed on the EML have changed dramatically because EML's selection process has changed from experience-based to evidence-based. For example, albumin, which had been listed since the 2nd edition (1979), was deleted in the 11th edition (2000) because of the uncertainty of its efficacy. Human immunoglobulin normal, which had been deleted from the 13th edition (2003), was relisted in the 15th edition (2007). Moreover, the WHO has issued several resolutions and guidelines regarding PFP production, quality, and safety in order to promote the establishment of blood programmes in every nation. The focus of WHO's EML selection process has changed over 30 years. In the 20th century, WHO mainly focused on PFP efficacy, quality, and safety problems. However, currently the focus is on the problem of PFP accessibility, especially in developing countries. Therefore, it would be important to know how to capitalize on established knowledge and production technology to increase the accessibility of PFP worldwide.

Development of an Implicit, Charge and Energy Conserving 2D Electromagnetic PIC Code on Advanced Architectures

NASA Astrophysics Data System (ADS)

Payne, Joshua; Taitano, William; Knoll, Dana; Liebs, Chris; Murthy, Karthik; Feltman, Nicolas; Wang, Yijie; McCarthy, Colleen; Cieren, Emanuel

2012-10-01

In order to solve problems such as the ion coalescence and slow MHD shocks fully kinetically we developed a fully implicit 2D energy and charge conserving electromagnetic PIC code, PlasmaApp2D. PlasmaApp2D differs from previous implicit PIC implementations in that it will utilize advanced architectures such as GPUs and shared memory CPU systems, with problems too large to fit into cache. PlasmaApp2D will be a hybrid CPU-GPU code developed primarily to run on the DARWIN cluster at LANL utilizing four 12-core AMD Opteron CPUs and two NVIDIA Tesla GPUs per node. MPI will be used for cross-node communication, OpenMP will be used for on-node parallelism, and CUDA will be used for the GPUs. Development progress and initial results will be presented.

[Use of adsorption methods for plasma component apheresis].

PubMed

Bang, B; Heegaard, N H

1991-11-25

Plasma-apheresis is a nonspecific and wasteful intervention requiring the use of potentially infectious and expensive replacement fluids. Selective removal of the unwanted plasma component circumvents most of the problems. For selective binding and removal of plasma components adsorption methods based on the principles of affinity chromatography have been useful. The ideal adsorption column still does not exist, but the number of clinical applications is increasing. The results vary, but the treatment has been used with success in hypercholesterolemia, and in patients with hemophilia with antifactor antibodies and patients with antibodies directed towards HLA-antigens awaiting renal transplantation. In conclusion selective plasma component-apheresis is an improvement in some diseases as compared to conventional plasma-apheresis. The technique is still being improved but large clinical trials examining the effects of plasma-component-apheresis have not yet been published.

The influence of the Hall term on the development of magnetized laser-produced plasma jets

NASA Astrophysics Data System (ADS)

Hamlin, N. D.; Seyler, C. E.; Khiar, B.

2018-04-01

We present 2D axisymmetric simulation results describing the influence of the Hall term on laser-produced plasma jets and their interaction with an applied magnetic field parallel to the laser axis. Bending of the poloidal B-field lines produces an MHD shock structure surrounding a conical cavity, and a jet is produced from the convergence of the shock envelope. Both the jet and the conical cavity underneath it are bound by fast MHD shocks. We compare the MHD results generated using the extended-MHD code Physics as an Extended-MHD Relaxation System with an Efficient Upwind Scheme (PERSEUS) with MHD results generated using GORGON and find reasonable agreement. We then present extended-MHD results generated using PERSEUS, which show that the Hall term has several effects on the plasma jet evolution. A hot low-density current-carrying layer of plasma develops just outside the plume, which results in a helical rather than a purely poloidal B-field, and reduces magnetic stresses, resulting in delayed flow convergence and jet formation. The flow is partially frozen into the helical field, resulting in azimuthal rotation of the jet. The Hall term also produces field-aligned current in strongly magnetized regions. In particular, we find the influence of Hall physics on this problem to be scale-dependent. This points to the importance of mitigating the Hall effect in a laboratory setup, by increasing the jet density and system dimensions, in order to avoid inaccurate extrapolation to astrophysical scales.

SHARP: A Spatially Higher-order, Relativistic Particle-in-cell Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shalaby, Mohamad; Broderick, Avery E.; Chang, Philip

Numerical heating in particle-in-cell (PIC) codes currently precludes the accurate simulation of cold, relativistic plasma over long periods, severely limiting their applications in astrophysical environments. We present a spatially higher-order accurate relativistic PIC algorithm in one spatial dimension, which conserves charge and momentum exactly. We utilize the smoothness implied by the usage of higher-order interpolation functions to achieve a spatially higher-order accurate algorithm (up to the fifth order). We validate our algorithm against several test problems—thermal stability of stationary plasma, stability of linear plasma waves, and two-stream instability in the relativistic and non-relativistic regimes. Comparing our simulations to exact solutionsmore » of the dispersion relations, we demonstrate that SHARP can quantitatively reproduce important kinetic features of the linear regime. Our simulations have a superior ability to control energy non-conservation and avoid numerical heating in comparison to common second-order schemes. We provide a natural definition for convergence of a general PIC algorithm: the complement of physical modes captured by the simulation, i.e., those that lie above the Poisson noise, must grow commensurately with the resolution. This implies that it is necessary to simultaneously increase the number of particles per cell and decrease the cell size. We demonstrate that traditional ways for testing for convergence fail, leading to plateauing of the energy error. This new PIC code enables us to faithfully study the long-term evolution of plasma problems that require absolute control of the energy and momentum conservation.« less

Evaluation of factors important in modeling plasma concentrations of tetracycline hydrochloride administered in water in swine.

PubMed

Mason, Sharon E; Almond, Glen W; Riviere, Jim E; Baynes, Ronald E

2012-10-01

To model the plasma tetracycline concentrations in swine (Sus scrofa domestica) treated with medication administered in water and determine the factors that contribute to the most accurate predictions of measured plasma drug concentrations. Plasma tetracycline concentrations measured in blood samples from 3 populations of swine. Data from previous studies provided plasma tetracycline concentrations that were measured in blood samples collected from 1 swine population at 0, 4, 8, 12, 24, 32, 48, 56, 72, 80, 96, and 104 hours and from 2 swine populations at 0, 12, 24, 48, and 72 hours hours during administration of tetracycline hydrochloride dissolved in water. A 1-compartment pharmacostatistical model was used to analyze 5 potential covariate schemes and determine factors most important in predicting the plasma concentrations of tetracycline in swine. 2 models most accurately predicted the tetracycline plasma concentrations in the 3 populations of swine. Factors of importance were body weight or age of pig, ambient temperature, concentration of tetracycline in water, and water use per unit of time. The factors found to be of importance, combined with knowledge of the individual pharmacokinetic and chemical properties of medications currently approved for administration in water, may be useful in more prudent administration of approved medications administered to swine. Factors found to be important in pharmacostatistical models may allow prediction of plasma concentrations of tetracycline or other commonly used medications administered in water. The ability to predict in vivo concentrations of medication in a population of food animals can be combined with bacterial minimum inhibitory concentrations to decrease the risk of developing antimicrobial resistance.

Numerical implementation of a cold-ion, Boltzmann-electron model for nonplanar plasma-surface interactions

NASA Astrophysics Data System (ADS)

Holgate, J. T.; Coppins, M.

2018-04-01

Plasma-surface interactions are ubiquitous in the field of plasma science and technology. Much of the physics of these interactions can be captured with a simple model comprising a cold ion fluid and electrons which satisfy the Boltzmann relation. However, this model permits analytical solutions in a very limited number of cases. This paper presents a versatile and robust numerical implementation of the model for arbitrary surface geometries in cartesian and axisymmetric cylindrical coordinates. Specific examples of surfaces with sinusoidal corrugations, trenches, and hemi-ellipsoidal protrusions verify this numerical implementation. The application of the code to problems involving plasma-liquid interactions, plasma etching, and electron emission from the surface is discussed.

Mass- and energy-analyses of ions from plasma by means of a miniature Thomson spectrometer.

PubMed

Sadowski, M J; Czaus, K; Malinowski, K; Skladnik-Sadowska, E; Zebrowski, J

2009-05-01

The paper presents an improved version of a miniature mass-spectrometer of the Thomson-type, which has been adopted for ion analysis near the dense plasma region inside a vacuum chamber. Problems connected with the separation of ions from plasma streams are considered. Input diaphragms and pumping systems, needed to ensure good vacuum inside the analyzing region, are described. The application of the miniature Thomson-type analyzer is illustrated by ion parabolas recorded in plasma-focus facility and rod plasma injector experiment. A quantitative analysis of the recorded ion parabolas is presented. Factors influencing accuracy of the ion analysis are discussed and methods of the spectrometer calibration are described.

Positive ion temperature effect on the plasma-wall transition

NASA Astrophysics Data System (ADS)

Morales Crespo, R.

2018-06-01

This paper analyses the plasma-wall interaction of a plasma in contact with a conducting planar surface when the positive-ion temperature is not negligible compared with the electron one. The electric potential from the plasma to the wall is obtained by the appropriate formulation of the model as an initial-value problem as well as some features useful for experimental applications, such as the positive current-to-voltage characteristics, the saturation current density, the floating potential or an estimation of the sheath thickness. Finally, it is analysed how all these quantities depend on the ionization degree and the positive-ion temperature.

On behavior peculiarity of electron plasma

NASA Astrophysics Data System (ADS)

Gordeeva, N. M.; Yushkanov, A. A.

2018-03-01

The analysis of the analytical solution of the problem of the behavior of electron plasma in the AC electric field is fulfilled. Debye mode describes shielding of the external electric field in the plasma. The analysis of the region of existence of Debye mode, depending on the plasma parameters has been realized. A non-trivial dependence of the region of existence of Debye mode on the degree of degeneracy of the electron gas are revealed. For the case of nearly degenerate electron gas Debye mode has several areas of existence, depending on the frequency of the electric field.

6.7 radio sky mapping from satellites at very low frequencies

NASA Technical Reports Server (NTRS)

Storey, L. R. O.

1991-01-01

Wave Distribution Function (WDF) analysis is a procedure for making sky maps of the sources of natural electromagnetic waves in space plasmas, given local measurements of some or all of the three magnetic and three electric field components. The work that still needs to be done on this subject includes solving basic methodological problems, translating the solution into efficient algorithms, and embodying the algorithms in computer software. One important scientific use of WDF analysis is to identify the mode of origin of plasmaspheric hiss. Some of the data from the Japanese satellite Akebono (EXOS D) are likely to be suitable for this purpose.

Radio sky mapping from satellites at very low frequencies

NASA Technical Reports Server (NTRS)

Storey, L. R. O.

1991-01-01

Wave Distribution Function (WDF) analysis is a procedure for making sky maps of the sources of natural electromagnetic waves in space plasmas, given local measurements of some or all of the three magnetic and three electric field components. The work that still needs to be done on this subject includes solving basic methodological problems, translating the solution into efficient algorithms, and embodying the algorithms in computer software. One important scientific use of WDF analysis is to identify the mode of origin of plasmaspheric hiss. Some of the data from the Japanese satellite Akebono (EXOS D) are likely to be suitable for this purpose.

Non-axisymmetric local magnetostatic equilibrium

DOE PAGES

Candy, Jefferey M.; Belli, Emily A.

2015-03-24

In this study, we outline an approach to the problem of local equilibrium in non-axisymmetric configurations that adheres closely to Miller's original method for axisymmetric plasmas. Importantly, this method is novel in that it allows not only specification of 3D shape, but also explicit specification of the shear in the 3D shape. A spectrally-accurate method for solution of the resulting nonlinear partial differential equations is also developed. We verify the correctness of the spectral method, in the axisymmetric limit, through comparisons with an independent numerical solution. Some analytic results for the two-dimensional case are given, and the connection to Boozermore » coordinates is clarified.« less

Cryoradiation sterilization—Contemporary state and outlook

NASA Astrophysics Data System (ADS)

Talrose, V. L.; Trofimov, V. I.

1995-02-01

The new approach of radiation sterilization — cryoradiosterilization with programmed freezing — was developed for pharmaceutical solutions. Both scientific and technical problems are solved, the results are discussed. Programmed freezing of vials with the drug's solutions provides the high stability of soluted components with biological activity at sterilizing irradiation without significant change of sterilization doses. Physical, chemical, biological and pharmacological properties of a lot of drug solutions for injection satisfy official requirements after cryoradiation sterilization treatment. This method seems to be especially important for the protein systems which could be infected by dangerous viruses (VIH, hepatitis B): blood plasma, diagnostic sera, protein preparations manufactured from donor's blood, etc.

Sacroiliac Joint Interventions.

PubMed

Soto Quijano, David A; Otero Loperena, Eduardo

2018-02-01

Sacroiliac joint (SIJ) pain is an important cause of lower back problems. Multiple SIJ injection techniques have been proposed over the years to help in the diagnosis and treatment of this condition. However, the SIJ innervation is complex and variable, and truly intra-articular injections are sometimes difficult to obtain. Different sacroiliac joint injections have shown to provide pain relief in patients suffering this ailment. Various techniques for intraarticular injections, sacral branch blocks and radiofrequency ablation, both fluoroscopy guided and ultrasound guided are discussed in this paper. Less common techniques like prolotherapy, platelet rich plasma injections and botulism toxin injections are also discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

Explicitly covariant dispersion relations and self-induced transparency

NASA Astrophysics Data System (ADS)

Mahajan, S. M.; Asenjo, Felipe A.

2017-02-01

Explicitly covariant dispersion relations for a variety of plasma waves in unmagnetized and magnetized plasmas are derived in a systematic manner from a fully covariant plasma formulation. One needs to invoke relatively little known invariant combinations constructed from the ambient electromagnetic fields and the wave vector to accomplish the program. The implication of this work applied to the self-induced transparency effect is discussed. Some problems arising from the inconsistent use of relativity are pointed out.

SXTF Description: AEDC and NASA Candidate Sites.

DTIC Science & Technology

1980-08-29

the PRS, this debris shield will have to withstand a rather severe plasma pulse and attendant shock fronts. The actual amount of material debris blown...multipurpose shield poses a particular problem in that the explosive nature of the plasma source will probably destroy at least portions of thedebris...source Plasma radiator Multiple bremsstrahlung source /kABSTRAC T iConftnue on roverse side It n- *ce4 aend Id’nttl’ I h’ block ns-nberl Modifications

Development of lithium and tungsten limiters for test on T-10 tokamak at high heat load condition

NASA Astrophysics Data System (ADS)

Lyublinski, I. E.; Vertkov, A. V.; Zharkov, M. Yu; Vershkov, V. A.; Mirnov, S. V.

2016-04-01

Application of a complex of powerful (up to 3 MW) ECR plasma heating in T-10 tokamak is pulled down with a problem of the strong plasma pollution at power input more than 2 MW. For the solution of these problems the new W and Li limiters is developed and prepared to implementation. As it is supposed, application of W as a plasma facing material will allow excluding carbon influx into vacuum chamber. An additional Li limiter arranged in a shadow of W one will be used as a Li source for plasma periphery cooling due to a reradiation on Li that will lead to decrease in power deposition on W limiters. Parameters and design of limiters are presented. Plasma facing surface of a limiter is made of capillary-porous system (CPS) with Li. Porous matrix of CPS (W felt) provides stability of liquid Li surface under MHD force effect and an opportunity of its constant renewal due to capillary forces. The necessary Li flux from a Li limiter surface is estimated for maintenance of normal operation mode of W limiters at ECRH power of 3 MW during 400 ms. It is shown, that upgrade of limiters in tokamak T-10 will allow providing of ECR plasma heating with power up to 3 MW at reasonable Li flux.

Effect of NTP Pretreatment on Thermal Resistance and Fouling Components of Oilfield Wastewater

NASA Astrophysics Data System (ADS)

Zhao, Jie; Li, Wenli; Zou, Longsheng; Fu, Honghun

2018-01-01

In order to prevent scaling in the process of oilfield wastewater evaporation, low temperature plasma is used for pretreatment of heavy oil wastewater. It reacts with the ions and radicals produced by the low-temperature plasma and then is send into the evaporator. The changes of various indexes of the distilled water and the distribution of fouling in the evaporation process of heavy oil wastewater after plasma pretreatment were studied. The results showed that the content and hardness of silica in wastewater were decreased after plasma pretreatment, which was more suitable for evaporation treatment. At the same time, the content of salt and oil in distilled water is reduced, and the quality is improved. In addition, when the steam concentration was 30∼40 times, the suspended solids in the concentrated solution of the wastewater increased significantly after the plasma treatment. Correspondingly, the fouling at the bottom of evaporator is greatly reduced. Comparing the various indexes of distilled water and the feed water index of gas injection boiler, it can be seen that the excessive oil content in distilled water is the biggest obstacle to the recovery of distilled water to boiler feed water. Low temperature plasma pretreatment can provide a quick and new way to solve the scaling problems and water quality problems in the recovery of distilled water from a large number of heavy oil wastewater.

Plasmoid formation in the elongated current sheet during transient CHI on HIST

NASA Astrophysics Data System (ADS)

Nagata, Masayoshi; Fujita, Akihiro; Matsui, Takahiro; Kikuchi, Yusuke; Fukumoto, Naoyuki; Kanki, Takashi

2016-10-01

The Transient-Coaxial Helicity Injection (T-CHI) is a promising candidate for the non-inductive plasma start-up on Spherical Torus (ST). The problem of the flux closure in the T-CHI is important and related to understand the physics of fast magnetic reconnection. The recent MHD simulation (F. Ebrahimi and R. Raman, Phys. Rev. Lett. 114, 205003 (2015)) on T-CHI for NSTX predicts the formation and breakup of an elongated Sweet-Parker (S-P) current sheet and a transient to plasmoid instability. According to this simulation, the reconnection rate based on the plasmoid instability is faster than that by S-P model and becomes nearly independent of the Lundquist number S. In this meeting, we will present that the formation of multiple X-points and plasmoids has been observed in T-CHI start-up plasmas on HIST. The stronger external guide (toroidal) magnetic field makes plasma less compressible, leading to slower reconnection time and longer current sheet. The experimental observation shows that 2/3 plasmoids are generated in the elongated current sheet with the narrow width comparable to the ion skin depth or the ion sound gyro-radius. The small plasmoids develop to a large-scale flux structure due to a current inward diffusion during the decay phase.

A novel hypothesis: The application of platelet-rich plasma can promote the clinical healing of white-white meniscal tears

PubMed Central

Wei, Li-Cheng; Gao, Shu-Guang; Xu, Mai; Jiang, Wei; Tian, Jian; Lei, Guang-Hua

2012-01-01

Summary The white-white tears (meniscus lesion completely in the avascular zone) are without blood supply and theoretically cannot heal. Basal research has demonstrated that menisci are unquestionably important in load bearing, load redistribution, shock absorption, joint lubrication and the stabilization of the knee joint. It has been proven that partial or all-meniscusectomy results in an accelerated degeneration of cartilage and an increased rate of early osteoarthritis. Knee surgeons must face the difficult decision of removing or, if possible, retaining the meniscus; if it is possible to retain the meniscus, surgeons must address the difficulties of meniscal healing. Some preliminary approaches have progressed to improve meniscal healing. However, the problem of promoting meniscal healing in the avascular area has not yet been resolved. The demanding nature of the approach as well as its low utility and efficacy has impeded the progress of these enhancement techniques. Platelet-rich plasma (PRP) is a platelet concentration derived from autologous blood. In recent years, PRP has been used widely in preclinical and clinical applications for bone regeneration and wound healing. Therefore, we hypothesize that the application of platelet-rich plasma for white-white meniscal tears will be a simple and novel technique of high utility in knee surgery. PMID:22847210

Dielectric response in Bloch’s hydrodynamic model of an electron-ion plasma

NASA Astrophysics Data System (ADS)

Ishikawa, K.; Felderhof, B. U.

The linear response of an electron-ion plasma to an applied oscillating electric field is studied within the framework of Bloch’s classical hydrodynamic model. The ions are assumed to be fixed in space and distributed according to a known probability distribution. The linearized equations of motion for electron density and flow velocity are studied with the aid of a multiple scattering analysis and cluster expansion. This allows systematic reduction of the many-ion problem to a composition of few-ion problems, and shows how the longitudinal dielectric response function can in principle be calculated.

Description and Operation of the Mark 1B Plasma Focus Radiation Facility,

DTIC Science & Technology

plasma focus facility (Mk 1B) at The Aerospace Corporation produces x-ray fluences that are applicable to most radiation testing problems (e.g., integrated circuits or transistors). Although the facility has only one beryllium window for exposing 1.6-cm-dia samples to doses of 25 to 45 krad (Si) per shot, three more windows could be added and the additional samples exposed simultaneously. The facility is experiencing switch problems and is presently averaging 50 shots per week--15 shots per day for 3 or 4 days. The results of a comprehensive switch analysis should

Applications of inductively coupled plasma mass spectrometry and laser ablation inductively coupled plasma mass spectrometry in materials science

NASA Astrophysics Data System (ADS)

Becker, Johanna Sabine

2002-12-01

Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) have been applied as the most important inorganic mass spectrometric techniques having multielemental capability for the characterization of solid samples in materials science. ICP-MS is used for the sensitive determination of trace and ultratrace elements in digested solutions of solid samples or of process chemicals (ultrapure water, acids and organic solutions) for the semiconductor industry with detection limits down to sub-picogram per liter levels. Whereas ICP-MS on solid samples (e.g. high-purity ceramics) sometimes requires time-consuming sample preparation for its application in materials science, and the risk of contamination is a serious drawback, a fast, direct determination of trace elements in solid materials without any sample preparation by LA-ICP-MS is possible. The detection limits for the direct analysis of solid samples by LA-ICP-MS have been determined for many elements down to the nanogram per gram range. A deterioration of detection limits was observed for elements where interferences with polyatomic ions occur. The inherent interference problem can often be solved by applying a double-focusing sector field mass spectrometer at higher mass resolution or by collision-induced reactions of polyatomic ions with a collision gas using an ICP-MS fitted with collision cell. The main problem of LA-ICP-MS is quantification if no suitable standard reference materials with a similar matrix composition are available. The calibration problem in LA-ICP-MS can be solved using on-line solution-based calibration, and different procedures, such as external calibration and standard addition, have been discussed with respect to their application in materials science. The application of isotope dilution in solution-based calibration for trace metal determination in small amounts of noble metals has been developed as a new calibration strategy. This review discusses new analytical developments and possible applications of ICP-MS and LA-ICP-MS for the quantitative determination of trace elements and in surface analysis for materials science.

Preliminary investigation on the use of low current pulsed power Z-pinch plasma devices for the study of early stage plasma instabilities

NASA Astrophysics Data System (ADS)

Kaselouris, E.; Dimitriou, V.; Fitilis, I.; Skoulakis, A.; Koundourakis, G.; Clark, E. L.; Chatzakis, J.; Bakarezos, Μ; Nikolos, I. K.; Papadogiannis, N. A.; Tatarakis, M.

2018-01-01

This article addresses key features for the implementation of low current pulsed power plasma devices for the study of matter dynamics from the solid to the plasma phase. The renewed interest in such low current plasma devices lies in the need to investigate methods for the mitigation of prompt seeding mechanisms for the generation of plasma instabilities. The low current when driven into thick wires (skin effect mode) allows for the simultaneous existence of all phases of matter from solid to plasma. Such studies are important for the concept of inertial confinement fusion where the mitigation of the instability seeding mechanisms arising from the very early moments within the target’s heating is of crucial importance. Similarly, in the magnetized liner inertial fusion concept it is an open question as to how much surface non-uniformity correlates with the magneto-Rayleigh-Taylor instability, which develops during the implosion. This study presents experimental and simulation results, which demonstrate that the use of low current pulsed power devices in conjunction with appropriate diagnostics can be important for studying seeding mechanisms for the imminent generation of plasma instabilities in future research.

Dissipative instability in a partially ionised prominence plasma slab

NASA Astrophysics Data System (ADS)

Ballai, I.; Pintér, B.; Oliver, R.; Alexandrou, M.

2017-07-01

Aims: We aim to investigate the nature of dissipative instability appearing in a prominence planar thread filled with partially ionised plasma in the incompressible limit. The importance of partial ionisation is investigated in terms of the ionisation factor and the wavelength of sausage and kink waves propagating in the slab. Methods: In order to highlight the role of partial ionisation, we have constructed models describing various situations we can meet in solar prominence fine structure. Matching the solutions for the transversal component of the velocity and total pressure at the interfaces between the prominence slab and surrounding plasmas, we derived a dispersion relation whose imaginary part describes the evolution of the instability. Results were obtained in the limit of weak dissipation. We have investigated the appearance of instabilities in prominence dark plumes using single and two-fluid approximations. Results: Using simple analytical methods, we show that dissipative instabilities appear for flow speeds that are less than the Kelvin-Helmholtz instability threshold. The onset of instability is determined by the equilibrium flow strength, the ionisation factor of the plasma, the wavelength of waves and the ion-neutral collisional rate. For a given wavelength and for ionisation degrees closer to a neutral gas, the propagating waves become unstable for a narrow band of flow speeds, meaning that neutrals have a stabilising effect. Our results show that the partially ionised plasma describing prominence dark plumes becomes unstable only in a two-fluid (charged particles-neutrals) model, that is for periods that are smaller than the ion-neutral collision time. Conclusions: The present study improves our understanding of the complexity of dynamical processes and stability of solar prominences and the role partial ionisation in destabilising the plasma. We showed the necessity of two-fluid approximation when discussing the nature of instabilities: waves in a single fluid approximation show a great deal of stability. Our results clearly show that the problem of partial ionisation introduces new aspects of plasma stability with consequences on the evolution of partially ionised plasmas and solar prominences, in particular.

Self-organized criticality and the dynamics of near-marginal turbulent transport in magnetically confined fusion plasmas

NASA Astrophysics Data System (ADS)

Sanchez, R.; Newman, D. E.

2015-12-01

The high plasma temperatures expected at reactor conditions in magnetic confinement fusion toroidal devices suggest that near-marginal operation could be a reality in future devices and reactors. By near-marginal it is meant that the plasma profiles might wander around the local critical thresholds for the onset of instabilities. Self-organized criticality (SOC) was suggested in the mid 1990s as a more proper paradigm to describe the dynamics of tokamak plasma transport in near-marginal conditions. It advocated that, near marginality, the evolution of mean profiles and fluctuations should be considered simultaneously, in contrast to the more common view of a large separation of scales existing between them. Otherwise, intrinsic features of near-marginal transport would be missed, that are of importance to understand the properties of energy confinement. In the intervening 20 years, the relevance of the idea of SOC for near-marginal transport in fusion plasmas has transitioned from an initial excessive hype to the much more realistic standing of today, which we will attempt to examine critically in this review paper. First, the main theoretical ideas behind SOC will be described. Secondly, how they might relate to the dynamics of near-marginal transport in real magnetically confined plasmas will be discussed. Next, we will review what has been learnt about SOC from various numerical studies and what it has meant for the way in which we do numerical simulation of fusion plasmas today. Then, we will discuss the experimental evidence available from the several experiments that have looked for SOC dynamics in fusion plasmas. Finally, we will conclude by identifying the various problems that still remain open to investigation in this area. Special attention will be given to the discussion of frequent misconceptions and ongoing controversies. The review also contains a description of ongoing efforts that seek effective transport models better suited than traditional equations to capture SOC dynamics. Most of these models, based on the use of fractional transport equations and related concepts, could prove useful both in reactor operation and experiment control and design.

Enhanced Erosion of Carbon Grains in a Hot Plasma

NASA Astrophysics Data System (ADS)

Bringa, E. M.; Johnson, R. E.; Salonen, E.; Nordlund, K. H.; Jurac, S.

2001-12-01

Grain creation and survival plays an important role in the overall mass balance, ionization state, and chemistry in the interstellar medium (ISM), in the early solar nebula and in the giant planet magnetospheres. Grain erosion by a high temperature plasma or in a shocked gas depends strongly on the values of the sputtering yield, Y. For instance, Draine [1] considered an energy dependence for Y extrapolated from high energy data and calculated a fractional erosion of less than 1% for a grain which encounters a shocked gas moving with a velocity vo < 90 km/s). Since carbon grains rapidly become hydrogenated in a space environment, we present new data based on accurate simulations for the sputtering of hydrogenated carbon surfaces [2]. The yield is larger at low velocities and is found to have a lower threshold for sputter erosion due to chemical sputtering effects. Here we present results of two sets of calculations. First we use the Draine model for erosion of a grain in a shock as in Jurac et al [3], but change the energy dependence of the sputtering yield based on our new simulation data. This leads to a grain destruction rate which is much larger than Draine's estimate. This worsens the problem of grain destruction in the ISM, which is already larger than currently accepted grain formation rates. Second we give the erosion rates vs. plasma temperature for such grains in a stationery plasma. These data can now be used for modeling grain erosion in the early solar system, in the solar wind or in a trapped plasma in a planetary magnetosphere. [1] B.T. Draine, Astrophys. Space Sci. 233, 111 (1995).\

Enrichment of low-molecular-weight proteins from biofluids for biomarker discovery.

PubMed

Chertov, Oleg; Simpson, John T; Biragyn, Arya; Conrads, Thomas P; Veenstra, Timothy D; Fisher, Robert J

2005-01-01

The dramatic progress in mass spectrometry-based methods of protein identification has triggered a new quest for disease-associated biomarkers. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and its variant surface-enhanced laser desorption/ionization mass spectrometry, provide effective means to explore the less studied information slice of the human serum proteome -- low-molecular-weight proteins and peptides. These low-molecular-weight proteins and peptides are promising for the detection of important biomarkers. Due to the significant experimental problems imposed by high-abundance and high-molecular-weight proteins, it is important to effectively remove these species prior to mass spectrometry analysis of the low-molecular-weight serum and plasma proteomes. In this review, the advantages afforded by recently introduced methods for prefractionation of serum, as they pertain to the detection and identification of biomarkers, will be discussed.

Antithrombin, an Important Inhibitor in Blood Clots.

PubMed

Zhu, Ying; Cong, Qing-Wei; Liu, Yue; Wan, Chun-Ling; Yu, Tao; He, Guang; He, Lin; Cai, Lei; Chou, Kuo-Chen

2016-01-01

Blood coagulation is healthy and lifesaving because it can stop bleeding. It can, however, be a troublemaker as well, causing serious medical problems including heart attack and stroke. Body has complex blood coagulation cascade to modulate the blood clots. In the environment of plasma, the blood coagulation cascade is regulated by antithrombin, which is deemed one of the most important serine protease inhibitors. It inhibits thrombin; it can inhibit factors IXa and Xa as well. Interestingly, its inhibitory ability will be significantly increased with the existence of heparin. In this minireview paper, we are to summarize the structural features of antithrombin, as well as its heparin binding modes and anti-coagulation mechanisms, in hopes that the discussion and analysis presented in this paper can stimulate new strategies to find more effective approaches or compounds to modulate the antithrombin.

Transient fields produced by a cylindrical electron beam flowing through a plasma

NASA Astrophysics Data System (ADS)

Firpo, Marie-Christine

2012-10-01

Fast ignition schemes (FIS) for inertial confinement fusion should involve in their final stage the interaction of an ignition beam composed of MeV electrons laser generated at the critical density surface with a dense plasma target. In this study, the out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire [1], is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented [2]. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions.[4pt] [1] J.S. Green et al., Surface heating of wire plasmas using laser-irradiated cone geometries, Nature Physics 3, 853--856 (2007).[0pt] [2] M.-C. Firpo, http://hal.archives-ouvertes.fr/hal-00695629, to be published (2012).

Quantifying the effect of non-Larmor motion of electrons on the pressure tensor

NASA Astrophysics Data System (ADS)

Che, H.; Schiff, C.; Le, G.; Dorelli, J. C.; Giles, B. L.; Moore, T. E.

2018-03-01

In space plasma, various effects of magnetic reconnection and turbulence cause the electron motion to significantly deviate from their Larmor orbits. Collectively these orbits affect the electron velocity distribution function and lead to the appearance of the "non-gyrotropic" elements in the pressure tensor. Quantification of this effect has important applications in space and laboratory plasma, one of which is tracing the electron diffusion region (EDR) of magnetic reconnection in space observations. Three different measures of agyrotropy of pressure tensor have previously been proposed, namely, A ∅ e , Dng, and Q. The multitude of contradictory measures has caused confusion within the community. We revisit the problem by considering the basic properties an agyrotropy measure should have. We show that A ∅ e , Dng, and Q are all defined based on the sum of the principle minors (i.e., the rotation invariant I2) of the pressure tensor. We discuss in detail the problems of I2-based measures and explain why they may produce ambiguous and biased results. We introduce a new measure AG constructed based on the determinant of the pressure tensor (i.e., the rotation invariant I3) which does not suffer from the problems of I2-based measures. We compare AG with other measures in 2- and 3-dimension particle-in-cell magnetic reconnection simulations and show that AG effectively trace the EDR of reconnection in both Harris and force-free current sheets. On the other hand, A ∅ e does not show prominent peaks in the EDR and part of the separatrix in the force-free reconnection simulations, demonstrating that A ∅ e does not measure all the non-gyrotropic effects in this case and is not suitable for studying magnetic reconnection in more general situations other than Harris sheet reconnection.

Study on monatomic fraction improvement with alumina layer on metal electrode in hydrogen plasma ion source.

PubMed

Jung, Bong-Ki; Chung, Kyoung-Jae; Dang, Jeong-Jeung; Hwang, Y S

2012-02-01

A high monatomic beam fraction is an important factor in a hydrogen ion source to increase the application efficiency. The monatomic fraction of hydrogen plasmas with different plasma electrode materials is measured in a helicon plasma ion source, and aluminum shows the highest value compared to that with the other metals such as copper and molybdenum. Formation of an aluminum oxide layer on the aluminum electrode is determined by XPS analysis, and the alumina layer is verified as the high monatomic fraction. Both experiments and numerical simulations conclude that a low surface recombination coefficient of the alumina layer on the plasma electrode is one of the most important parameters for increasing the monatomic fraction in hydrogen plasma ion sources.

Study on monatomic fraction improvement with alumina layer on metal electrode in hydrogen plasma ion sourcea)

NASA Astrophysics Data System (ADS)

Jung, Bong-Ki; Chung, Kyoung-Jae; Dang, Jeong-Jeung; Hwang, Y. S.

2012-02-01

A high monatomic beam fraction is an important factor in a hydrogen ion source to increase the application efficiency. The monatomic fraction of hydrogen plasmas with different plasma electrode materials is measured in a helicon plasma ion source, and aluminum shows the highest value compared to that with the other metals such as copper and molybdenum. Formation of an aluminum oxide layer on the aluminum electrode is determined by XPS analysis, and the alumina layer is verified as the high monatomic fraction. Both experiments and numerical simulations conclude that a low surface recombination coefficient of the alumina layer on the plasma electrode is one of the most important parameters for increasing the monatomic fraction in hydrogen plasma ion sources.

Revision of the criterion to avoid electron heating during laser aided plasma diagnostics (LAPD)

NASA Astrophysics Data System (ADS)

Carbone, E. A. D.; Palomares, J. M.; Hübner, S.; Iordanova, E.; van der Mullen, J. J. A. M.

2012-01-01

A criterion is given for the laser fluency (in J/m2) such that, when satisfied, disturbance of the plasma by the laser is avoided. This criterion accounts for laser heating of the electron gas intermediated by electron-ion (ei) and electron-atom (ea) interactions. The first heating mechanism is well known and was extensively dealt with in the past. The second is often overlooked but of importance for plasmas of low degree of ionization. It is especially important for cold atmospheric plasmas, plasmas that nowadays stand in the focus of attention. The new criterion, based on the concerted action of both ei and ea interactions is validated by Thomson scattering experiments performed on four different plasmas.

Computational modeling of joint U.S.-Russian experiments relevant to magnetic compression/magnetized target fusion (MAGO/MTF)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheehey, P.T.; Faehl, R.J.; Kirkpatrick, R.C.

1997-12-31

Magnetized Target Fusion (MTF) experiments, in which a preheated and magnetized target plasma is hydrodynamically compressed to fusion conditions, present some challenging computational modeling problems. Recently, joint experiments relevant to MTF (Russian acronym MAGO, for Magnitnoye Obzhatiye, or magnetic compression) have been performed by Los Alamos National Laboratory and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF). Modeling of target plasmas must accurately predict plasma densities, temperatures, fields, and lifetime; dense plasma interactions with wall materials must be characterized. Modeling of magnetically driven imploding solid liners, for compression of target plasmas, must address issues such as Rayleigh-Taylor instability growthmore » in the presence of material strength, and glide plane-liner interactions. Proposed experiments involving liner-on-plasma compressions to fusion conditions will require integrated target plasma and liner calculations. Detailed comparison of the modeling results with experiment will be presented.« less

La projection par plasma : une revue

NASA Astrophysics Data System (ADS)

Fauchais, P.; Grimaud, A.; Vardelle, A.; Vardelle, M.

The quality of a plasma sprayed coating depends on numerous parameters that start to be understood due to the recent progresses in modelling and measurement techniques for plasma jets, momentum, heat and mass transfers between plasma and particles, the way the particules splat and cool down upon impact on the substrate or the previously deposited layers. In this paper, first are recalled the used measurement techniques and their limitations both for plasma jets and particles in flight. Then are underlined the importance of the different phenomena envolved in the transfers between plasma and particles such as steep temperature and chemical species density gradients around the particles, heat propagation phenomenon especially for ceramic particles and the connected evaporation effect, rarefaction effect which occurs even at atmospheric pressure. The problems related to the size and injection velocity distributions which determine the trajectory distributions and the heat treatments undergone by the particles are treated. The study of plasma generation shows on one hand for d.c. arc plasma torches the drastic influence on the plasma jets lengths and diameters of the gas injection chamber design, the gas nature, the design of the arc chamber and nozzle, the surrounding atmosphere (especially air pumping which cools down very fast the plasma) and on the other hand for RF plasmas the importance of the particle injection design to avoid the coupling between the RF discharge and the carrier gas with the particles. All these points are illustrated with examples of coatings of alumina, zirconia carbide and nickel particles. The way the particles splat is then studied with the chemical reactions in flight, the fast quenching of the particles and the resulting cristalline structures, the coating adhesion and also the residual stesses and their control through that of the temperature gradients into the coatings during spraying. At last a few actual and potential applications are presented in the fields of aeronautics and mechanics. La qualité d'un dépôt projete par plasma dépend de nombreux paramètres que l'on commence à mieux appréhender du fait des progrès de la modélisation et de la métrologie tant des écoulements plasmas que des transferts plasma-particules ou que des conditions d'écrasement et de refroidissement des particules lors de leur impact sur le substrat ou les couches déjà déposées. Les techniques de mesure utilisdes et leurs limitations sont d'abord rappelées tant pour les jets de plasma que pour les particules en vol et l'importance des différents phénomènes intervenant dans les transferts plasma-particules est soulignée : gradients de température et de concentration d'espèces chimiques très élevés autour des particules, effets de propagation de la chaleur, notamment pour les particules céramiques, effet d'évaporation, effet de raréfaction sensible dès la pression atmosphérique. Les problèmes de distribution de taille et de vitesse d'injection des particules sont également abordés car ils conditionnent les distributions de trajectoires et donc le traitement des particules dans le jet de plasma. La génération du plasma montre d'une part 1'influence considérable de l'injection du gaz, de sa nature, du dessin de la chambre d'arc et de la tuyère ainsi que du pompage de l'air ambiant sur la longueur des jets de plasma d'arc et d'autre part les problèmes d'injection pour éviter le couplage avec la décharge dans les jets de plasmas R.E Tout ceci est illustré avec des exemples de dépôt d'alumine, de zircone, de cermet carbure et de nickel. L'écrasement des particules est ensuite abordé avec les problèmes de réactions chimiques, de trempe ultra-rapide et donc de structure cristalline des dépôts, d'adhdsion mais aussi de containtes résiduelles et de leur contrôle via les gradients de température dans les dépôts pendant le tir. Enfin quelques applications actuelles sont présentées notamment pour l'aéronautique et la mécanique.

Gravitational force and the cardiovascular system

NASA Technical Reports Server (NTRS)

Pendergast, D. R.; Olszowka, A. J.; Rokitka, M. A.; Farhi, L. E.

1991-01-01

Ground-based simulation studies have been conducted to clarify the problems of the cardiovascular adaptation to alterations in gravitational force. Simulated microgravity experiments resulted in increases in cardiac stretch, urine flow, and sodium excretion, which were accompanied by lower plasma renin, aldosterone, and ADH. There appears to be a decrease in plasma volume as well as in sympathetic tone after 2-3 days of 0 Gz. Complete adjustment to 0 Gz is found within 8 h without a decrease in plasma volume, when subjects are allowed to dehydrate mildly.

Research Progress in Plasma arc welding of Magnesium Alloys and Magnesium Matrix Composites

NASA Astrophysics Data System (ADS)

Hui, Li; Yang, Zou; Yongbo, Li; Lei, Jiao; Ruijun, Hou

2017-11-01

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

REVIEWS OF TOPICAL PROBLEMS: Particle kinetics in highly turbulent plasmas (renormalization and self-consistent field methods)

NASA Astrophysics Data System (ADS)

Bykov, Andrei M.; Toptygin, Igor'N.

1993-11-01

This review presents methods available for calculating transport coefficients for impurity particles in plasmas with strong long-wave MHD-type velocity and magnetic-field fluctuations, and random ensembles of strong shock fronts. The renormalization of the coefficients of the mean-field equation of turbulent dynamo theory is also considered. Particular attention is devoted to the renormalization method developed by the authors in which the renormalized transport coefficients are calculated from a nonlinear transcendental equation (or a set of such equations) and are expressed in the form of explicit functions of pair correlation tensors describing turbulence. Numerical calculations are reproduced for different turbulence spectra. Spatial transport in a magnetic field and particle acceleration by strong turbulence are investigated. The theory can be used in a wide range of practical problems in plasma physics, atmospheric physics, ocean physics, astrophysics, cosmic-ray physics, and so on.

PREFACE: Theory of Fusion Plasmas, 13th Joint Varenna-Lausanne International Workshop (2012)

NASA Astrophysics Data System (ADS)

Garbet, Xavier; Sauter, Olivier

2012-12-01

The 2012 joint Varenna-Lausanne international workshop on the theory of fusion plasmas has been very fruitful. A broad variety of topics were addressed, as usual covering turbulence, MHD, edge physic, RF wave heating and a taste of astrophysics. Moreover the scope of the meeting was extended this year to include the physics of materials and diagnostics for burning plasmas. This evolution reflects the complexity of problems at hand in fusion, in particular in the context of ITER construction. Long-standing problems without immediate consequences have sometimes become an urgent matter in that context. One may quote for instance the choice of plasma facing components or the design of control systems. Another characteristic of the meeting is the interplay between various domains of plasma physics. For instance MHD modes are now currently investigated with gyrokinetic codes, kinetic effects are more and more included in MHD stability analysis, and turbulence is now accounted for in wave propagation problems. This is the proof of cross-fertilization and it is certainly a healthy sign in our community. Finally introducing some novelty in the programme does not prevent us from respecting the traditions of the meeting. As usual a good deal of the presentations were dedicated to numerical simulations. Combining advanced numerical techniques with elaborated analytical theory is certainly a trademark of the Varenna-Lausanne conference, which was respected again this year. The quality and size of the scientific production is illustrated by the 26 papers which appear in the present volume of Journal of Physics: Conference Series, all refereed. We would also like to mention another set of 20 papers to be published in Plasma Physics and Controlled Fusion. We hope the readers will enjoy this special issue of JPCS and the one to come in PPCF. Xavier Garbet and Olivier Sauter October 26, 2012

The ZPIC educational code suite

NASA Astrophysics Data System (ADS)

Calado, R.; Pardal, M.; Ninhos, P.; Helm, A.; Mori, W. B.; Decyk, V. K.; Vieira, J.; Silva, L. O.; Fonseca, R. A.

2017-10-01

Particle-in-Cell (PIC) codes are used in almost all areas of plasma physics, such as fusion energy research, plasma accelerators, space physics, ion propulsion, and plasma processing, and many other areas. In this work, we present the ZPIC educational code suite, a new initiative to foster training in plasma physics using computer simulations. Leveraging on our expertise and experience from the development and use of the OSIRIS PIC code, we have developed a suite of 1D/2D fully relativistic electromagnetic PIC codes, as well as 1D electrostatic. These codes are self-contained and require only a standard laptop/desktop computer with a C compiler to be run. The output files are written in a new file format called ZDF that can be easily read using the supplied routines in a number of languages, such as Python, and IDL. The code suite also includes a number of example problems that can be used to illustrate several textbook and advanced plasma mechanisms, including instructions for parameter space exploration. We also invite contributions to this repository of test problems that will be made freely available to the community provided the input files comply with the format defined by the ZPIC team. The code suite is freely available and hosted on GitHub at https://github.com/zambzamb/zpic. Work partially supported by PICKSC.

Fields and Plasma Structures Around ``Shining'' Black Holes: Solitary Rings and Tri-dimensional Topologies

NASA Astrophysics Data System (ADS)

Coppi, B.

2012-03-01

Field and plasma configurations that can be the distinguishing feature of and surround ``shining'' black holes have been identified. Considering the observation of the Quasi Periodic Oscillations that can be associated with inhomogeneous rotating plasmas, tri-dimensional rotating configurations have been looked for and found under special conditions. One is that these configurations are radially localized, such as narrow plasma ring pairs. Another is that the rotation frequency is nearly constant over the rings. Only axisymmetric local configurations consisting of solitary plasma rings or periodic sequences of rings are found when the gradient of the rotation frequency is (locally) significant. Assuming that the plasma pressure is scalar the problem is reduced to the solution of two coupled non-linear differential equations. One, the ``Master Equation'' [1], relates the magnetic surface function to the plasma rotation frequency that is connected to the gravity field. The other, the Vertical Equilibrium Equation, relates the plasma pressure gradient to both the Lorentz force and to the plasma density profile through the gravitational force.[4pt] [1] B. Coppi, Phys. Plasmas 18, 032901 (2011).

Computational extended magneto-hydrodynamical study of shock structure generated by flows past an obstacle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xuan, E-mail: xzhao@cylance.com; Seyler, C. E., E-mail: ces7@cornell.edu

2015-07-15

The magnetized shock problem is studied in the context where supersonic plasma flows past a solid obstacle. This problem exhibits interesting and important phenomena such as a bow shock, magnetotail formation, reconnection, and plasmoid formation. This study is carried out using a discontinuous Galerkin method to solve an extended magneto-hydrodynamic model (XMHD). The main goals of this paper are to present a reasonably complete picture of the properties of this interaction using the MHD model and then to compare the results to the XMHD model. The inflow parameters, such as the magnetosonic Mach number M{sub f} and the ratio ofmore » thermal pressure to magnetic pressure β, can significantly affect the physical structures of the flow-obstacle interaction. The Hall effect can also significantly influence the results in the regime in which the ion inertial length is numerically resolved. Most of the results presented are for the two-dimensional case; however, two three-dimensional simulations are presented to make a connection to the important case in which the solar wind interacts with a solid body and to explore the possibility of performing scaled laboratory experiments.« less

A Critical Review on Clinical Application of Separation Techniques for Selective Recognition of Uracil and 5-Fluorouracil.

PubMed

Pandey, Khushaboo; Dubey, Rama Shankar; Prasad, Bhim Bali

2016-03-01

The most important objectives that are frequently found in bio-analytical chemistry involve applying tools to relevant medical/biological problems and refining these applications. Developing a reliable sample preparation step, for the medical and biological fields is another primary objective in analytical chemistry, in order to extract and isolate the analytes of interest from complex biological matrices. Since, main inborn errors of metabolism (IEM) diagnosable through uracil analysis and the therapeutic monitoring of toxic 5-fluoruracil (an important anti-cancerous drug) in dihydropyrimidine dehydrogenase deficient patients, require an ultra-sensitive, reproducible, selective, and accurate analytical techniques for their measurements. Therefore, keeping in view, the diagnostic value of uracil and 5-fluoruracil measurements, this article refines several analytical techniques involved in selective recognition and quantification of uracil and 5-fluoruracil from biological and pharmaceutical samples. The prospective study revealed that implementation of molecularly imprinted polymer as a solid-phase material for sample preparation and preconcentration of uracil and 5-fluoruracil had proven to be effective as it could obviates problems related to tedious separation techniques, owing to protein binding and drastic interferences, from the complex matrices in real samples such as blood plasma, serum samples.

A nonlocal fluid closure for antiparallel reconnection

NASA Astrophysics Data System (ADS)

Ng, J.; Hakim, A.; Bhattacharjee, A.

2016-12-01

The integration of kinetic effects in fluid models is an important problem in global simulations of the Earth's magnetosphere and space weather modelling. In particular, it has been shown that ion kinetics play an important role in the dynamics of large reconnecting systems, and that fluid models can account of some of these effects[1,2] . Here we introduce a new fluid model and closure for collisionless magnetic reconnection and more general applications. Taking moments of the kinetic equation, we evolve the full pressure tensor for electrons and ions, which includes the off diagonal terms necessary for reconnection. Kinetic effects are recovered by using a nonlocal heat flux closure, which approximates linear Landau damping in the fluid framework [3]. Using the island coalescence problem as a test, we show how the nonlocal ion closure improves on the typical collisional closures used for ten-moment models and circumvents the need for a colllisional free parameter. Finally, we extend the closure to study guide-field reconnection and discuss the implementation of a twenty-moment model.[1] A. Stanier et al. Phys Rev Lett (2015)[2] J. Ng et al. Phys Plasmas (2015)[3] G. Hammett et al. Phys Rev Lett (1990)

A tandem mirror hybrid plume plasma propulsion facility

NASA Technical Reports Server (NTRS)

Yang, T. F.; Krueger, W. A.; Peng, S.; Urbahn, J.; Chang-Diaz, F. R.

1988-01-01

This paper discusses a novel concept in electrodeless plasma propulsion, in which the materials problems are ameliorated by an electrodeless magnetic confinement scheme borrowed from the tandem mirror approach to controlled thermonuclear fusion. The concept also features a two-stage magnetic nozzle with an annular hypersonic coaxial gas injector near the throat. The nozzle produces hybrid plume by the coaxial injection of hypersonic neutral gas, and the gas layer thus formed protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The tandem mirror plasma propulsion facility is capable of delivering a variable I(sp). The results of numerical simulation of this concept are presented together with those from an experimental tandem-mirror plasma propulsion device.

The influence of surface properties of plasma-etched polydimethylsiloxane (PDMS) on cell growth and morphology.

PubMed

Pennisi, Cristian P; Zachar, Vladimir; Gurevich, Leonid; Patriciu, Andrei; Struijk, Johannes J

2010-01-01

Polydimethylsiloxane (PDMS) or silicone rubber is a widely used implant material. Approaches to promote tissue integration to PDMS are desirable to avoid clinical problems associated with sliding and friction between tissue and implant. Plasma-etching is a useful way to control cell behavior on PDMS without additional coatings. In this work, different plasma processing conditions were used to modify the surface properties of PDMS substrates. Surface nanotopography and wettability were measured to study their effect on in vitro growth and morphology of fibroblasts. While fluorinated plasma treatments produced nanorough hydrophobic and superhydrophobic surfaces that had negative or little influences on cellular behavior, water vapor/oxygen plasma produced smooth hydrophillic surfaces that enhanced cell growth.

Influence of external magnetic field on laser-induced gold nanoparticles fragmentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serkov, A. A.; The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology; Rakov, I. I.

Laser-assisted fragmentation is an efficient method of the nanoparticles size and morphology control. However, its exact mechanisms are still under consideration. One of the remaining problems is the plasma formation, inevitably occurring upon the high intensity laser irradiation. In this Letter, the role of the laser-induced plasma is studied via introduction of high-intensity external magnetic field (up to 7.5 T). Its presence is found to cause the plasma emission to start earlier regarding to a laser pulse, also increasing the plume luminosity. Under these conditions, the acceleration of nanoparticles fragmentation down to a few nanometers is observed. Laser-induced plasma interaction withmore » magnetic field and consequent energy transfer from plasma to nanoparticles are discussed.« less

Targeting biofilms with cold plasma: new approaches to a persistent problem

USDA-ARS?s Scientific Manuscript database

For the food industry, almost nothing presents as many problems for antimicrobial sanitation as the increased difficulties presented by biofilms. Biofilms are tightly-grouped masses of microorganisms, clustered together in complex communities to provide water-impermeable cellular protection. What ma...

Widespread confusion in the modeling of Europa's magnetospheric interaction: what the potential modeler should consider before getting started

NASA Astrophysics Data System (ADS)

Cassidy, T. A.

2016-12-01

Understanding Europa's interaction with Jupiter's magnetosphere is a critical part of the ocean sounding objective of the upcoming Clipper mission and interpretation of these observations will require modeling efforts that build upon studies done over the last four decades. Unfortunately, these studies are often confusing and contradictory. There is, as yet, no community consensus on the assumptions and parameters that go into such models. There is enough uncertainty in this problem that I cannot tell anyone, with certainty, what they should and should not do, but in this presentation I will outline what modelers should at least consider before starting. The most important consideration that is often missing in the literature is plasma flow diversion. Many papers assume that Europa's interaction is lunar-like; a completely absorbing barrier. Data and plasma models show that there is likely significant diversion, and such diversion could prevent the bulk of magnetospheric plasa particles from reaching the surface. On the other hand, some models likely overestimate the amount of diversion: we do know that a significant amount of plasma must reach the surface in order to produce the atmosphere via sputtering and radiolysis, but most plasma models usually treat the atmosphere as a fixed boundary condition. A second consideration is energy range of particles responsible for radiolysis and sputtering. The particles bombarding the surface range from thermal plasma (eV-keV) to non-thermal (keV-MeV), but to many modelers, it seems, these are indistinguishable despite drastic differences in how these populations interact with the moon. To illustrate this confusion, the attached figure shows the O2 source rate (O2 is likely the dominant atmospheric component) from published Europa atmosphere/plasma models. There is little agreement on either the source rate or the particle population responsible for its production. Finally, I will discuss how experiences with other planetary bodies can inform Europa science.

Turbulent Heating and Fluctuation Characteristics in Alfvenic Turbulence

NASA Astrophysics Data System (ADS)

Dorland, William

2005-10-01

Alfve'n waves are ubiquitous in natural and laboratory plasmas. In this talk, the main focus is on astrophysical plasmas that are turbulent, magnetized, hot and diffuse. The dynamically important characteristics of these plasmas are often well- described by magnetohydrodynamics [see e.g., Ref. 1]. However, much of what we actually observe is critically affected by how much of the turbulent energy is absorbed by (highly radiative) electrons [2], the amplitude of density fluctuations [3], and the spectral indices of turbulent, Alfve'nic cascades. These questions each have essentially kinetic aspects. In this talk, we present detailed simulations and analyses of of the cascade of shear Alfve'n waves, to and through scales comparable to the ion Larmor radius in the direction perpendicular to the magnetic field. We demonstrate analytically and numerically that the nonlinear gyrokinetic equations, originally developed for fusion applications, are perfectly suited to these astrophysical problems. We present extensive linear and nonlinear gyrokinetic simulation results from the GS2 code. We demonstrate accurate resolution of the damping of kinetic Alfve'n waves in plasmas with beta small, large and comparable to unity, for a wide range of electron-to-ion temperature ratios, in linear and nonlinear contexts. We have used the GS2 code to calculate the turbulent energy absorption, density fluctuation characteristics, and spectral indices for plasmas with parameters taken from hot accretion flows and from the interstellar plasma. These results will be compared with theoretical predictions [2] and to observations. Co-authors: S. C. Cowley (UCLA), G. W. Hammett (PPPL), E. Quataert and G. Howes (UC-Berkeley), and A. Scheckochihin (Cambridge) 1. S. Balbus and J. Hawley, Rev Mod Phys, Vol. 70, p. 1. 2. E. Quataert and A. Gruzinov, Ap J, Vol. 520, p. 248; E. Quataert, Ap J, Vol. 500, p. 978.3. Y. Lithwick and P. Goldreich, Ap J, Vol. 562, p. 279.4. P. Goldreich and Sridhar, Ap J, Vol. 438, p. 763; P. Goldreich and Sridhar, Ap J, Vol. 485, p. 680.

Maternal and fetal plasma zinc in pre-eclampsia.

PubMed

Bassiouni, B A; Foda, A I; Rafei, A A

1979-04-01

Zinc is important for fetal growth and is involved in several important enzyme systems. Maternal and umbilical plasma zinc concentrations were determined in 52 parturient women with mild and severe pre-eclampsia, and were compared with those obtained from 20 women in labor whose pregnancies had progressed normally. A decrease in maternal as well as umbilical plasma zinc concentrations was observed in pre-eclamptic women, and this decrease was statistically significant in severe pre-eclampsia. The causes of these changes in plasma zinc concentrations in pre-eclampsia were discussed, and the possible adverse effects of zinc deficiency on the mother and fetus were mentioned. Low plasma zinc concentrations in pre-eclampsia may be a sign of zinc deficiency, implying possible risks to the mother and her fetus. It is recommended that maintenance of adequate dietary zinc nutrition during pregnancy, and particularly in pre-eclampsia, is important.

Studies of Plasma Instabilities using Unstructured Discontinuous Galerkin Method with the Two-Fluid Plasma Model

NASA Astrophysics Data System (ADS)

Song, Yang; Srinivasan, Bhuvana

2017-10-01

The discontinuous Galerkin (DG) method has the advantage of resolving shocks and sharp gradients that occur in neutral fluids and plasmas. An unstructured DG code has been developed in this work to study plasma instabilities using the two-fluid plasma model. Unstructured meshes are known to produce small and randomized grid errors compared to traditional structured meshes. Computational tests for Rayleigh-Taylor instabilities in radially-converging flows are performed using the MHD model. Choice of grid geometry is not obvious for simulations of instabilities in these circular configurations. Comparisons of the effects for different grids are made. A 2D magnetic nozzle simulation using the two-fluid plasma model is also performed. A vacuum boundary condition technique is applied to accurately solve the Riemann problem on the edge of the plume.

Blood safety--a focus on plasma derivatives in Mainland China.

PubMed

Zhu, Y M

2007-01-01

Plasma derivative production in Mainland China can be encapsulated by two figures: 50 years of history and 5000 tons of annually processed source plasma. Demands for albumin, immunoglobulinin and main clotting factors can barely be met, despite a relatively low average usage among China's population of 1.3 billion. The tragedy of contamination among plasma donors in Henan province in the early 1990's has left shadows on the safety of the plasma derivative industry. However, during the last ten years the Chinese government has made great strides forward. The regulation of the entire operation has been strengthened, from law and standard setting and upholding to stricter licensing regulations for plasma centers and fractionators. Public concerns in blood safety are gradually being relieved, and confidence is returning. Nevertheless, the plasma donors and hemophilia patients infected a decade ago by infected blood or plasma products represent a set of severe social and medical problems that the government and society must still deal with.

Diagnostics for the plasma liner experiment.

PubMed

Lynn, A G; Merritt, E; Gilmore, M; Hsu, S C; Witherspoon, F D; Cassibry, J T

2010-10-01

The goal of the Plasma Liner Experiment (PLX) is to explore and demonstrate the feasibility of forming imploding spherical "plasma liners" via merging high Mach number plasma jets to reach peak liner pressures of ∼0.1 Mbar using ∼1.5 MJ of initial stored energy. Such a system would provide HED plasmas for a variety of fundamental HEDLP, laboratory astrophysics, and materials science studies, as well as a platform for experimental validation of rad-hydro and rad-MHD simulations. It could also prove attractive as a potential standoff driver for magnetoinertial fusion. Predicted parameters from jet formation to liner stagnation cover a large range of plasma density and temperature, varying from n(i)∼10(16) cm(-3), T(e)≈T(i)∼1 eV at the plasma gun mouth to n(i)>10(19) cm(-3), T(e)≈T(i)∼0.5 keV at stagnation. This presents a challenging problem for the plasma diagnostics suite which will be discussed.

The thermal X-ray flare plasma. [on sun

NASA Technical Reports Server (NTRS)

Moore, R.; Mckenzie, D. L.; Svestka, Z.; Widing, K. G.; Dere, K. P.; Antiochos, S. K.; Dodson-Prince, H. W.; Hiei, E.; Krall, K. R.; Krieger, A. S.

1980-01-01

Following a review of current observational and theoretical knowledge of the approximately 10 to the 7th K plasma emitting the thermal soft X-ray bursts accompanying every H alpha solar flare, the fundamental physical problem of the plasma, namely the formation and evolution of the observed X-ray arches, is examined. Extensive Skylab observations of the thermal X-ray plasmas in two large flares, a large subflare and several compact subflares are analyzed to determine plasma physical properties, deduce the dominant physical processes governing the plasma and compare large and small flare characteristics. Results indicate the density of the thermal X-ray plasma to be higher than previously thought (from 10 to the 10th to 10 to the 12th/cu cm for large to small flares), cooling to occur radiatively as much as conductively, heating to continue into the decay phase of large flares, and the mass of the thermal X-ray plasma to be supplied primarily through chromospheric evaporation. Implications of the results for the basic flare mechanism are indicated.

Final Technical Report: Magnetic Reconnection in High-Energy Laser-Produced Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Germaschewski, Kai; Fox, William; Bhattacharjee, Amitava

This report describes the final results from the DOE Grant DE-SC0007168, “Fast Magnetic Reconnection in HED Laser-Produced Plasmas.” The recent generation of laboratory high-energy-density physics facilities has opened significant physics opportunities for experimentally modeling astrophysical plasmas. The goal of this proposal is to use these new tools to study fundamental problems in plasma physics and plasma astrophysics. Fundamental topics in this area involve study of the generation, amplification, and fate of magnetic fields, which are observed to pervade the plasma universe and govern its evolution. This project combined experiments at DOE laser facilities with kinetic plasma simulation to study thesemore » processes. The primary original goal of the project was to study magnetic reconnection using a new experimental platform, colliding magnetized laser-produced plasmas. However through a series of fortuitous discoveries, the work broadened out to allow significant advancement on multiple topics in laboratory astrophysics, including magnetic reconnection, Weibel instability, and collisionless shocks.« less

Advances in continuum kinetic and gyrokinetic simulations of turbulence on open-field line geometries

NASA Astrophysics Data System (ADS)

Hakim, Ammar; Shi, Eric; Juno, James; Bernard, Tess; Hammett, Greg

2017-10-01

For weakly collisional (or collisionless) plasmas, kinetic effects are required to capture the physics of micro-turbulence. We have implemented solvers for kinetic and gyrokinetic equations in the computational plasma physics framework, Gkeyll. We use a version of discontinuous Galerkin scheme that conserves energy exactly. Plasma sheaths are modeled with novel boundary conditions. Positivity of distribution functions is maintained via a reconstruction method, allowing robust simulations that continue to conserve energy even with positivity limiters. We have performed a large number of benchmarks, verifying the accuracy and robustness of our code. We demonstrate the application of our algorithm to two classes of problems (a) Vlasov-Maxwell simulations of turbulence in a magnetized plasma, applicable to space plasmas; (b) Gyrokinetic simulations of turbulence in open-field-line geometries, applicable to laboratory plasmas. Supported by the Max-Planck/Princeton Center for Plasma Physics, the SciDAC Center for the Study of Plasma Microturbulence, and DOE Contract DE-AC02-09CH11466.

Compact Plasma Accelerator for Micropropulsion Applications

NASA Technical Reports Server (NTRS)

Foster, John E.

2001-01-01

There is a need for a low power, light-weight (compact), high specific impulse electric propulsion device to satisfy mission requirements for microsatellite (1 to 20 kg) class missions. Satisfying these requirements entails addressing the general problem of generating a sufficiently dense plasma within a relatively small volume and then accelerating it. In the work presented here, the feasibility of utilizing a magnetic cusp to generate a dense plasma over small length scales of order 1 mm is investigated. This approach could potentially mitigate scaling issues associated with conventional ion thruster plasma containment schemes. Plume and discharge characteristics were documented using a Faraday probe and a retarding potential analyzer.

REVIEWS OF TOPICAL PROBLEMS: lonization and quenching of excited atoms with the production of fast electrons

NASA Astrophysics Data System (ADS)

Kolokolov, N. B.; Blagoev, A. B.

1993-03-01

Studies of reactions involving excited atoms, which result in the release of electrons with energies exceeding the mean plasma electron energy, are reviewed. Particular attention is devoted to plasma electron spectroscopy (PES) which combines the advantages of studies of elementary plasma processes with those of traditional electron spectroscopy. Data obtained by investigating the following reactions are reported: chemoionization with the participation of two excited inert-gas atoms, Penning ionization of atoms and molecules by metastable helium atoms, and electron quenching of excited inert-gas atoms and mercury atoms. The effect of processes in which fast electrons are emitted on plasma properties is discussed.

The distribution of radio plasma in time and space.

PubMed

Blundell, Katherine M

2005-03-15

The influence of jet-ejected plasma has been an important theme of this meeting; I draw attention to the prevalence of jet-ejected plasma, in particular that which has not been properly accounted for in the past. There are three strands to this paper: important emission which is prominent only at the lowest radio frequencies; relic radio plasma which must exist if even the most basic aspects of radio source evolutionary models are correct; and evidence that some 'radio-quiet' quasars could be FR-I radio sources.

Review of heat transfer problems associated with magnetically-confined fusion reactor concepts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, M.A.; Werner, R.W.; Carlson, G.A.

1976-04-01

Conceptual design studies of possible fusion reactor configurations have revealed a host of interesting and sometimes extremely difficult heat transfer problems. The general requirements imposed on the coolant system for heat removal of the thermonuclear power from the reactor are discussed. In particular, the constraints imposed by the fusion plasma, neutronics, structure and magnetic field environment are described with emphasis on those aspects which are unusual or unique to fusion reactors. Then the particular heat transfer characteristics of various possible coolants including lithium, flibe, boiling alkali metals, and helium are discussed in the context of these general fusion reactor requirements.more » Some specific areas where further experimental and/or theoretical work is necessary are listed for each coolant along with references to the pertinent research already accomplished. Specialized heat transfer problems of the plasma injection and removal systems are also described. Finally, the challenging heat transfer problems associated with the superconducting magnets are reviewed, and once again some of the key unsolved heat transfer problems are enumerated.« less

Nonlinear gyrokinetics: a powerful tool for the description of microturbulence in magnetized plasmas

NASA Astrophysics Data System (ADS)

Krommes, John A.

2010-12-01

Gyrokinetics is the description of low-frequency dynamics in magnetized plasmas. In magnetic-confinement fusion, it provides the most fundamental basis for numerical simulations of microturbulence; there are astrophysical applications as well. In this tutorial, a sketch of the derivation of the novel dynamical system comprising the nonlinear gyrokinetic (GK) equation (GKE) and the coupled electrostatic GK Poisson equation will be given by using modern Lagrangian and Lie perturbation methods. No background in plasma physics is required in order to appreciate the logical development. The GKE describes the evolution of an ensemble of gyrocenters moving in a weakly inhomogeneous background magnetic field and in the presence of electromagnetic perturbations with wavelength of the order of the ion gyroradius. Gyrocenters move with effective drifts, which may be obtained by an averaging procedure that systematically, order by order, removes gyrophase dependence. To that end, the use of the Lagrangian differential one-form as well as the content and advantages of Lie perturbation theory will be explained. The electromagnetic fields follow via Maxwell's equations from the charge and current density of the particles. Particle and gyrocenter densities differ by an important polarization effect. That is calculated formally by a 'pull-back' (a concept from differential geometry) of the gyrocenter distribution to the laboratory coordinate system. A natural truncation then leads to the closed GK dynamical system. Important properties such as GK energy conservation and fluctuation noise will be mentioned briefly, as will the possibility (and difficulties) of deriving nonlinear gyrofluid equations suitable for rapid numerical solution—although it is probably best to directly simulate the GKE. By the end of the tutorial, students should appreciate the GKE as an extremely powerful tool and will be prepared for later lectures describing its applications to physical problems.

Creation of second order magnetic barrier inside chaos created by NTMs in the ASDEX UG

NASA Astrophysics Data System (ADS)

Ali, Halima; Punjabi, Alkesh

2012-10-01

Understanding and stabilization of neoclassical tearing modes (NTM) in tokamaks is an important problem. For low temperature plasmas, tearing modes are believed to be mainly driven by current density gradient. For collisionless plasmas, even when plasma is stable to classical tearing modes, helical reduction in bootstrap current in O-point of an island can destabilize NTMs when an initial island is seeded by other global MHD instabilities or when microturbulence triggers the transition from a linear to nonlinear instability. The onset of NTMs leads to the most serious beta limit in ASDEX UG tokamak [O. Gubner et al 2005 NF 39 1321]. The important NTMs in the ASDDEX UG are (m,n)=(3,2)+(4,3)+(1,1). Realistic parameterization of these NTMs and the safety factor in ASDEX UG are given in [O. Dumbrajs et al 2005 POP 12 1107004]. We use a symplectic map in magnetic coordinates for the ASDEX UG to integrate field lines in presence of the NTMs. We add a second order control term [H. Ali and A. Punjabi 2007 PPCF 49 1565] to this ASDEX UG field line Hamiltonian to create an invariant magnetic surface inside the chaos generated by the NTMs. The relative strength, robustness, and resilience of this barrier are studied to ascertain the most desirable noble barrier in the ASDEX UG with NTMs. We present preliminary results of this work, and discuss its implications with regard to magnetic transport barriers for increasing strength of magnetic perturbations. This work is supported by the grants DE-FG02-01ER54624 and DE-FG02-04ER54793.

Capabilities of Fully Parallelized MHD Stability Code MARS

NASA Astrophysics Data System (ADS)

Svidzinski, Vladimir; Galkin, Sergei; Kim, Jin-Soo; Liu, Yueqiang

2016-10-01

Results of full parallelization of the plasma stability code MARS will be reported. MARS calculates eigenmodes in 2D axisymmetric toroidal equilibria in MHD-kinetic plasma models. Parallel version of MARS, named PMARS, has been recently developed at FAR-TECH. Parallelized MARS is an efficient tool for simulation of MHD instabilities with low, intermediate and high toroidal mode numbers within both fluid and kinetic plasma models, implemented in MARS. Parallelization of the code included parallelization of the construction of the matrix for the eigenvalue problem and parallelization of the inverse vector iterations algorithm, implemented in MARS for the solution of the formulated eigenvalue problem. Construction of the matrix is parallelized by distributing the load among processors assigned to different magnetic surfaces. Parallelization of the solution of the eigenvalue problem is made by repeating steps of the MARS algorithm using parallel libraries and procedures. Parallelized MARS is capable of calculating eigenmodes with significantly increased spatial resolution: up to 5,000 adapted radial grid points with up to 500 poloidal harmonics. Such resolution is sufficient for simulation of kink, tearing and peeling-ballooning instabilities with physically relevant parameters. Work is supported by the U.S. DOE SBIR program.

Fully Parallel MHD Stability Analysis Tool

NASA Astrophysics Data System (ADS)

Svidzinski, Vladimir; Galkin, Sergei; Kim, Jin-Soo; Liu, Yueqiang

2015-11-01

Progress on full parallelization of the plasma stability code MARS will be reported. MARS calculates eigenmodes in 2D axisymmetric toroidal equilibria in MHD-kinetic plasma models. It is a powerful tool for studying MHD and MHD-kinetic instabilities and it is widely used by fusion community. Parallel version of MARS is intended for simulations on local parallel clusters. It will be an efficient tool for simulation of MHD instabilities with low, intermediate and high toroidal mode numbers within both fluid and kinetic plasma models, already implemented in MARS. Parallelization of the code includes parallelization of the construction of the matrix for the eigenvalue problem and parallelization of the inverse iterations algorithm, implemented in MARS for the solution of the formulated eigenvalue problem. Construction of the matrix is parallelized by distributing the load among processors assigned to different magnetic surfaces. Parallelization of the solution of the eigenvalue problem is made by repeating steps of the present MARS algorithm using parallel libraries and procedures. Results of MARS parallelization and of the development of a new fix boundary equilibrium code adapted for MARS input will be reported. Work is supported by the U.S. DOE SBIR program.

A Green's function method for local and non-local parallel transport in general magnetic fields

NASA Astrophysics Data System (ADS)

Del-Castillo-Negrete, Diego; Chacón, Luis

2009-11-01

The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion and astrophysics research. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), χ, and the perpendicular, χ, conductivities (χ/χ may exceed 10^10 in fusion plasmas); (ii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates; and (iii) Nonlocal parallel transport in the limit of small collisionality. Motivated by these issues, we present a Lagrangian Green's function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields. The numerical implementation employs a volume-preserving field-line integrator [Finn and Chac'on, Phys. Plasmas, 12 (2005)] for an accurate representation of the magnetic field lines regardless of the level of stochasticity. The general formalism and its algorithmic properties are discussed along with illustrative analytical and numerical examples. Problems of particular interest include: the departures from the Rochester--Rosenbluth diffusive scaling in the weak magnetic chaos regime, the interplay between non-locality and chaos, and the robustness of transport barriers in reverse shear configurations.

Development of a laboratory demonstration model active cleaning device

NASA Technical Reports Server (NTRS)

Shannon, R. L.; Gillette, R. B.

1975-01-01

A laboratory demonstration model of a device for removing contaminant films from optical surfaces in space was developed. The development of a plasma tube, which would produce the desired cleaning effects under high vacuum conditions, represented the major problem in the program. This plasma tube development is discussed, and the resulting laboratory demonstration-model device is described.

Hypercube technology

NASA Technical Reports Server (NTRS)

Parker, Jay W.; Cwik, Tom; Ferraro, Robert D.; Liewer, Paulett C.; Patterson, Jean E.

1991-01-01

The JPL designed MARKIII hypercube supercomputer has been in application service since June 1988 and has had successful application to a broad problem set including electromagnetic scattering, discrete event simulation, plasma transport, matrix algorithms, neural network simulation, image processing, and graphics. Currently, problems that are not homogeneous are being attempted, and, through this involvement with real world applications, the software is evolving to handle the heterogeneous class problems efficiently.

Divertor target shape optimization in realistic edge plasma geometry

NASA Astrophysics Data System (ADS)

Dekeyser, W.; Reiter, D.; Baelmans, M.

2014-07-01

Tokamak divertor design for next-step fusion reactors heavily relies on numerical simulations of the plasma edge. Currently, the design process is mainly done in a forward approach, where the designer is strongly guided by his experience and physical intuition in proposing divertor shapes, which are then thoroughly assessed by numerical computations. On the other hand, automated design methods based on optimization have proven very successful in the related field of aerodynamic design. By recasting design objectives and constraints into the framework of a mathematical optimization problem, efficient forward-adjoint based algorithms can be used to automatically compute the divertor shape which performs the best with respect to the selected edge plasma model and design criteria. In the past years, we have extended these methods to automated divertor target shape design, using somewhat simplified edge plasma models and geometries. In this paper, we build on and extend previous work to apply these shape optimization methods for the first time in more realistic, single null edge plasma and divertor geometry, as commonly used in current divertor design studies. In a case study with JET-like parameters, we show that the so-called one-shot method is very effective is solving divertor target design problems. Furthermore, by detailed shape sensitivity analysis we demonstrate that the development of the method already at the present state provides physically plausible trends, allowing to achieve a divertor design with an almost perfectly uniform power load for our particular choice of edge plasma model and design criteria.

Geotail MCA Plasma Wave Investigation Data Analysis

NASA Technical Reports Server (NTRS)

Anderson, Roger R.

1997-01-01

The primary goals of the International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program are identifying, studying, and understanding the source, movement, and dissipation of plasma mass, momentum, and energy between the Sun and the Earth. The GEOTAIL spacecraft was built by the Japanese Institute of Space and Astronautical Science and has provided extensive measurements of entry, storage, acceleration, and transport in the geomagnetic tail and throughout the Earth's outer magnetosphere. GEOTAIL was launched on July 24, 1992, and began its scientific mission with eighteen extensions into the deep-tail region with apogees ranging from around 60 R(sub e) to more than 208 R(sub e) in the period up to late 1994. Due to the nature of the GEOTAIL trajectory which kept the spacecraft passing into the deep tail, GEOTAIL also made 'magnetopause skimming passes' which allowed measurements in the outer magnetosphere, magnetopause, magnetosheath, bow shock, and upstream solar wind regions as well as in the lobe, magnetosheath, boundary layers, and central plasma sheet regions of the tail. In late 1994, after spending nearly 30 months primarily traversing the deep tail region, GEOTAIL began its near-Earth phase. Perigee was reduced to 10 R(sub e) and apogee first to 50 R(sub e) and finally to 30 R(sub e) in early 1995. This orbit provides many more opportunities for GEOTAIL to explore the upstream solar wind, bow shock, magnetosheath, magnetopause, and outer magnetosphere as well as the near-Earth tail regions. The WIND spacecraft was launched on November 1, 1994 and the POLAR spacecraft was launched on February 24, 1996. These successful launches have dramatically increased the opportunities for GEOTAIL and the GGS spacecraft to be used to conduct the global research for which the ISTP program was designed. The measurement and study of plasma waves have made and will continue to make important contributions to reaching the ISTP/GGS goals and solving the significant problems of sun-earth connections. Plasma waves are involved in the energization and de-energization of plasma and energetic particles via numerous wave-particle interaction processes. Plasma waves in many instances are the source for the heating or cooling of the particles. They can cause particle precipitation by scattering particles into the loss cone. They move particles across boundaries in mass and energy dependent ways. Identifying the waves and the instabilities which produce them are thus crucial for understanding the plasma processes. Wave-particle interaction processes are especially important at various boundaries between the different regions of geospace including the bow shock, magnetopause, and interfaces in the geomagnetic tail between the magnetosheath, lobe, plasmasheet, boundary layers, and neutral sheet. In addition to identifying the characteristics of the instabilities and generation mechanisms encountered, plasma wave measurement are used in conjunction with other fields and particle measurements to identify the region of space the spacecraft is in or the boundary that is being crosed.

Maxwell Prize Talk: Scaling Laws for the Dynamical Plasma Phenomena

NASA Astrophysics Data System (ADS)

Ryutov, Livermore, Ca 94550, Usa, D. D.

2017-10-01

The scaling and similarity technique is a powerful tool for developing and testing reduced models of complex phenomena, including plasma phenomena. The technique has been successfully used in identifying appropriate simplified models of transport in quasistationary plasmas. In this talk, the similarity and scaling arguments will be applied to highly dynamical systems, in which temporal evolution of the plasma leads to a significant change of plasma dimensions, shapes, densities, and other parameters with respect to initial state. The scaling and similarity techniques for dynamical plasma systems will be presented as a set of case studies of problems from various domains of the plasma physics, beginning with collisonless plasmas, through intermediate collisionalities, to highly collisional plasmas describable by the single-fluid MHD. Basic concepts of the similarity theory will be introduced along the way. Among the results discussed are: self-similarity of Langmuir turbulence driven by a hot electron cloud expanding into a cold background plasma; generation of particle beams in disrupting pinches; interference between collisionless and collisional phenomena in the shock physics; similarity for liner-imploded plasmas; MHD similarities with an emphasis on the effect of small-scale (turbulent) structures on global dynamics. Relations between astrophysical phenomena and scaled laboratory experiments will be discussed.

Nonlinear mixing of electromagnetic waves in plasmas.

PubMed

Stefan, V; Cohen, B I; Joshi, C

1989-01-27

Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves.

Tomographic diagnostics of nonthermal plasmas

NASA Astrophysics Data System (ADS)

Denisova, Natalia

2009-10-01

In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

Risk assessment of the application of a plasma jet in dermatology

NASA Astrophysics Data System (ADS)

Lademann, Juergen; Richter, Heike; Alborova, Alena; Humme, Daniel; Patzelt, Alexa; Kramer, Axel; Weltmann, Klaus-Dieter; Hartmann, Bernd; Ottomann, Christian; Fluhr, Joachim W.; Hinz, Peter; Hübner, Georg; Lademann, Olaf

2009-09-01

Regardless of the fact that several highly efficient antiseptics are commercially available, the antiseptic treatment of chronic wounds remains a problem. In the past, electrical plasma discharges have been frequently used in biometrical science for disinfection and sterilization of material surfaces. Plasma systems usually have a temperature of several hundred degrees. Recently, it was reported that ``cold'' plasma can be applied onto living tissue. In in vitro studies on cell culture, it could be demonstrated that this new plasma possesses excellent antiseptic properties. We perform a risk assessment concerning the in vivo application of a ``cold'' plasma jet on patients and volunteers. Two potential risk factors, UV radiation and temperature, are evaluated. We show that the UV radiation of the plasma in the used system is an order of magnitude lower than the minimal erythema dose, necessary to produce sunburn on the skin in vivo. Additionally, thermal damage of the tissue by the plasma can be excluded. The results of the risk assessment stimulate the in vivo application of the investigated plasma jet in the treatment of chronic wounds.

Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toi, K.; Ogawa, K.; Isobe, M.

2011-01-01

Comprehensive understanding of energetic-ion-driven global instabilities such as Alfven eigenmodes (AEs) and their impact on energetic ions and bulk plasma is crucially important for tokamak and stellarator/helical plasmas and in the future for deuterium-tritium (DT) burning plasma experiments. Various types of global modes and their associated enhanced energetic ion transport are commonly observed in toroidal plasmas. Toroidicity-induced AEs and ellipticity-induced AEs, whose gaps are generated through poloidal mode coupling, are observed in both tokamak and stellarator/helical plasmas. Global AEs and reversed shear AEs, where toroidal couplings are not as dominant were also observed in those plasmas. Helicity induced AEs thatmore » exist only in 3D plasmas are observed in the large helical device (LHD) and Wendelstein 7 Advanced Stellarator plasmas. In addition, the geodesic acoustic mode that comes from plasma compressibility is destabilized by energetic ions in both tokamak and LHD plasmas. Nonlinear interaction of these modes and their influence on the confinement of the bulk plasma as well as energetic ions are observed in both plasmas. In this paper, the similarities and differences in these instabilities and their consequences for tokamak and stellarator/helical plasmas are summarized through comparison with the data sets obtained in LHD. In particular, this paper focuses on the differences caused by the rotational transform profile and the 2D or 3D geometrical structure of the plasma equilibrium. Important issues left for future study are listed.« less

Understanding turbulence in compressing plasmas and its exploitation or prevention.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidovits, Seth

Unprecedented densities and temperatures are now achieved in compressions of plasma, by lasers and by pulsed power, in major experimental facilities. These compressions, carried out at the largest scale at the National Ignition Facility and at the Z Pulsed Power Facility, have important applications, including fusion, X-ray production, and materials research. Several experimental and simulation results suggest that the plasma in some of these compressions is turbulent. In fact, measurements suggest that in certain laboratory plasma compressions the turbulent energy is a dominant energy component. Similarly, turbulence is dominant in some compressing astrophysical plasmas, such as in molecular clouds. Turbulencemore » need not be dominant to be important; even small quantities could greatly influence experiments that are sensitive to mixing of non-fuel into fuel, such as compressions seeking fusion ignition. Despite its important role in major settings, bulk plasma turbulence under compression is insufficiently understood to answer or even to pose some of the most fundamental questions about it. This thesis both identifies and answers key questions in compressing turbulent motion, while providing a description of the behavior of three-dimensional, isotropic, compressions of homogeneous turbulence with a plasma viscosity. This description includes a simple, but successful, new model for the turbulent energy of plasma undergoing compression. The unique features of compressing turbulence with a plasma viscosity are shown, including the sensitivity of the turbulence to plasma ionization, and a sudden viscous dissipation'' effect which rapidly converts plasma turbulent energy into thermal energy. This thesis then examines turbulence in both laboratory compression experiments and molecular clouds. It importantly shows: the possibility of exploiting turbulence to make fusion or X-ray production more efficient; conditions under which hot-spot turbulence can be prevented; and a lower bound on the growth of turbulence in molecular clouds. This bound raises questions about the level of dissipation in existing molecular cloud models. Finally, the observations originally motivating the thesis, Z-pinch measurements suggesting dominant turbulent energy, are reexamined by self-consistently accounting for the impact of the turbulence on the spectroscopic analysis. This is found to strengthen the evidence that the multiple observations describe a highly turbulent plasma state.« less

Understanding Turbulence in Compressing Plasmas and Its Exploitation or Prevention

NASA Astrophysics Data System (ADS)

Davidovits, Seth

Unprecedented densities and temperatures are now achieved in compressions of plasma, by lasers and by pulsed power, in major experimental facilities. These compressions, carried out at the largest scale at the National Ignition Facility and at the Z Pulsed Power Facility, have important applications, including fusion, X-ray production, and materials research. Several experimental and simulation results suggest that the plasma in some of these compressions is turbulent. In fact, measurements suggest that in certain laboratory plasma compressions the turbulent energy is a dominant energy component. Similarly, turbulence is dominant in some compressing astrophysical plasmas, such as in molecular clouds. Turbulence need not be dominant to be important; even small quantities could greatly influence experiments that are sensitive to mixing of non-fuel into fuel, such as compressions seeking fusion ignition. Despite its important role in major settings, bulk plasma turbulence under compression is insufficiently understood to answer or even to pose some of the most fundamental questions about it. This thesis both identifies and answers key questions in compressing turbulent motion, while providing a description of the behavior of three-dimensional, isotropic, compressions of homogeneous turbulence with a plasma viscosity. This description includes a simple, but successful, new model for the turbulent energy of plasma undergoing compression. The unique features of compressing turbulence with a plasma viscosity are shown, including the sensitivity of the turbulence to plasma ionization, and a "sudden viscous dissipation'' effect which rapidly converts plasma turbulent energy into thermal energy. This thesis then examines turbulence in both laboratory compression experiments and molecular clouds. It importantly shows: the possibility of exploiting turbulence to make fusion or X-ray production more efficient; conditions under which hot-spot turbulence can be prevented; and a lower bound on the growth of turbulence in molecular clouds. This bound raises questions about the level of dissipation in existing molecular cloud models. Finally, the observations originally motivating the thesis, Z-pinch measurements suggesting dominant turbulent energy, are reexamined by self-consistently accounting for the impact of the turbulence on the spectroscopic analysis. This is found to strengthen the evidence that the multiple observations describe a highly turbulent plasma state.

Edge and divertor plasma: detachment, stability, and plasma-wall interactions

NASA Astrophysics Data System (ADS)

Krasheninnikov, S. I.; Kukushkin, A. S.; Lee, Wonjae; Phsenov, A. A.; Smirnov, R. D.; Smolyakov, A. I.; Stepanenko, A. A.; Zhang, Yanzeng

2017-10-01

The paper presents an overview of the results of studies on a wide range of the edge plasma related issues. The rollover of the plasma flux to the target during progressing detachment process is shown to be caused by the increase of the impurity radiation loss and volumetric plasma recombination, whereas the ion-neutral friction, although important for establishing the necessary edge plasma conditions, does not contribute per se to the rollover of the plasma flux to the target. The processes limiting the power loss by impurity radiation are discussed and a simple estimate of this limit is obtained. Different mechanisms of meso-scale thermal instabilities driven by impurity radiation and resulting in self-sustained oscillations in the edge plasma are identified. An impact of sheared magnetic field on the dynamics of the blobs and ELM filaments playing an important role in the edge and SOL plasma transport is discussed. Trapping of He, which is an intrinsic impurity for the fusion plasmas, in the plasma-facing tungsten material is considered. A newly developed model, accounting for the generation of additional He traps caused by He bubble growth, fits all the available experimental data on the layer of nano-bubbles observed in W under irradiation by low energy He plasma.

The Influence of the Hall Term on the Development of Magnetized Laser-Produced Plasma Jets

DOE PAGES

Hamlin, N.D.; Seyler, C. E.; Khiar, B.

2018-04-29

We present 2D axisymmetric simulation results describing the influence of the Hall term on laser-produced plasma jets and their interaction with an applied magnetic field parallel to the laser axis. Bending of the poloidal B-field lines produces an MHD shock structure surrounding a conical cavity, and a jet is produced from the convergence of the shock envelope. Both the jet and the conical cavity underneath it are bound by fast MHD shocks. We compare the MHD results generated using the extended-MHD code Physics as an Extended-MHD Relaxation System with an Efficient Upwind Scheme (PERSEUS) with MHD results generated using GORGONmore » and find reasonable agreement. We then present extended-MHD results generated using PERSEUS, which show that the Hall term has several effects on the plasma jet evolution. A hot low-density current-carrying layer of plasma develops just outside the plume, which results in a helical rather than a purely poloidal B-field, and reduces magnetic stresses, resulting in delayed flow convergence and jet formation. The flow is partially frozen into the helical field, resulting in azimuthal rotation of the jet. The Hall term also produces field-aligned current in strongly magnetized regions. In particular, we find the influence of Hall physics on this problem to be scale-dependent. In conclusion, this points to the importance of mitigating the Hall effect in a laboratory setup, by increasing the jet density and system dimensions, in order to avoid inaccurate extrapolation to astrophysical scales.« less

The Influence of the Hall Term on the Development of Magnetized Laser-Produced Plasma Jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamlin, N.D.; Seyler, C. E.; Khiar, B.

We present 2D axisymmetric simulation results describing the influence of the Hall term on laser-produced plasma jets and their interaction with an applied magnetic field parallel to the laser axis. Bending of the poloidal B-field lines produces an MHD shock structure surrounding a conical cavity, and a jet is produced from the convergence of the shock envelope. Both the jet and the conical cavity underneath it are bound by fast MHD shocks. We compare the MHD results generated using the extended-MHD code Physics as an Extended-MHD Relaxation System with an Efficient Upwind Scheme (PERSEUS) with MHD results generated using GORGONmore » and find reasonable agreement. We then present extended-MHD results generated using PERSEUS, which show that the Hall term has several effects on the plasma jet evolution. A hot low-density current-carrying layer of plasma develops just outside the plume, which results in a helical rather than a purely poloidal B-field, and reduces magnetic stresses, resulting in delayed flow convergence and jet formation. The flow is partially frozen into the helical field, resulting in azimuthal rotation of the jet. The Hall term also produces field-aligned current in strongly magnetized regions. In particular, we find the influence of Hall physics on this problem to be scale-dependent. In conclusion, this points to the importance of mitigating the Hall effect in a laboratory setup, by increasing the jet density and system dimensions, in order to avoid inaccurate extrapolation to astrophysical scales.« less

Integral methods of solving boundary-value problems of nonstationary heat conduction and their comparative analysis

NASA Astrophysics Data System (ADS)

Kot, V. A.

2017-11-01

The modern state of approximate integral methods used in applications, where the processes of heat conduction and heat and mass transfer are of first importance, is considered. Integral methods have found a wide utility in different fields of knowledge: problems of heat conduction with different heat-exchange conditions, simulation of thermal protection, Stefantype problems, microwave heating of a substance, problems on a boundary layer, simulation of a fluid flow in a channel, thermal explosion, laser and plasma treatment of materials, simulation of the formation and melting of ice, inverse heat problems, temperature and thermal definition of nanoparticles and nanoliquids, and others. Moreover, polynomial solutions are of interest because the determination of a temperature (concentration) field is an intermediate stage in the mathematical description of any other process. The following main methods were investigated on the basis of the error norms: the Tsoi and Postol’nik methods, the method of integral relations, the Gudman integral method of heat balance, the improved Volkov integral method, the matched integral method, the modified Hristov method, the Mayer integral method, the Kudinov method of additional boundary conditions, the Fedorov boundary method, the method of weighted temperature function, the integral method of boundary characteristics. It was established that the two last-mentioned methods are characterized by high convergence and frequently give solutions whose accuracy is not worse that the accuracy of numerical solutions.

[Primary hyperaldosteronism: problems of diagnostic approaches].

PubMed

Widimský, Jiří

2015-05-01

Primary hyperaldosteronism (PH) is common cause of endocrine/secondary hypertension with autonomous aldosterone overproduction by adrenal cortex. PH is typically characterized by hypertension, hypokalemia, high plasma aldosterone/renin ratio, high aldosterone, suppressed renin and nonsupressibilty of aldosterone during confirmatory tests. Diagnosis of PH can be difficult since hypokalemia is found only in 50 % of cases and measurement of the parameters of renin-angiotensin-aldosterone system can be influenced by several factors. Morphological dia-gnosis requires in majority of cases adrenal venous sampling. Early diagnostic and therapeutic measures are very important due to high prevalence of PH and potential cure. Patients with suspicion to PH should be investigated in experienced hypertensive centers due to relatively difficult laboratory and morphological diagnostic approaches.

Coordinated science with the Solar Orbiter, Solar Probe Plus, Interhelioprobe and SPORT missions

NASA Astrophysics Data System (ADS)

Maksimovic, Milan; Vourlidas, Angelos; Zimovets, Ivan; Velli, Marco; Zhukov, Andrei; Kuznetsov, Vladimir; Liu, Ying; Bale, Stuart; Ming, Xiong

The concurrent science operations of the ESA Solar Orbiter (SO), NASA Solar Probe Plus (SPP), Russian Interhelioprobe (IHP) and Chinese SPORT missions will offer a truly unique epoch in heliospheric science. While each mission will achieve its own important science objectives, taken together the four missions will be capable of doing the multi-point measurements required to address many problems in Heliophysics such as the coronal origin of the solar wind plasma and magnetic field or the way the Solar transients drive the heliospheric variability. In this presentation, we discuss the capabilities of the four missions and the Science synergy that will be realized by concurrent operations

Plasma membrane theory in nutrient uptake and rhizotoxicity

USDA-ARS?s Scientific Manuscript database

A clear understanding of plant-ion interactions is required to address problems of plant nutrition, toxicity, and the alleviation of toxicity. One or a combination of these problems limits productivity and persistence of pasture species (and other agronomic species) in vast regions of the world. F...

Atomic and molecular data for spacecraft re-entry plasmas

NASA Astrophysics Data System (ADS)

Celiberto, R.; Armenise, I.; Cacciatore, M.; Capitelli, M.; Esposito, F.; Gamallo, P.; Janev, R. K.; Laganà, A.; Laporta, V.; Laricchiuta, A.; Lombardi, A.; Rutigliano, M.; Sayós, R.; Tennyson, J.; Wadehra, J. M.

2016-06-01

The modeling of atmospheric gas, interacting with the space vehicles in re-entry conditions in planetary exploration missions, requires a large set of scattering data for all those elementary processes occurring in the system. A fundamental aspect of re-entry problems is represented by the strong non-equilibrium conditions met in the atmospheric plasma close to the surface of the thermal shield, where numerous interconnected relaxation processes determine the evolution of the gaseous system towards equilibrium conditions. A central role is played by the vibrational exchanges of energy, so that collisional processes involving vibrationally excited molecules assume a particular importance. In the present paper, theoretical calculations of complete sets of vibrationally state-resolved cross sections and rate coefficients are reviewed, focusing on the relevant classes of collisional processes: resonant and non-resonant electron-impact excitation of molecules, atom-diatom and molecule-molecule collisions as well as gas-surface interaction. In particular, collisional processes involving atomic and molecular species, relevant to Earth (N2, O2, NO), Mars (CO2, CO, N2) and Jupiter (H2, He) atmospheres are considered.

Dynamic mode decomposition for plasma diagnostics and validation.

PubMed

Taylor, Roy; Kutz, J Nathan; Morgan, Kyle; Nelson, Brian A

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Dynamic mode decomposition for plasma diagnostics and validation

NASA Astrophysics Data System (ADS)

Taylor, Roy; Kutz, J. Nathan; Morgan, Kyle; Nelson, Brian A.

2018-05-01

We demonstrate the application of the Dynamic Mode Decomposition (DMD) for the diagnostic analysis of the nonlinear dynamics of a magnetized plasma in resistive magnetohydrodynamics. The DMD method is an ideal spatio-temporal matrix decomposition that correlates spatial features of computational or experimental data while simultaneously associating the spatial activity with periodic temporal behavior. DMD can produce low-rank, reduced order surrogate models that can be used to reconstruct the state of the system with high fidelity. This allows for a reduction in the computational cost and, at the same time, accurate approximations of the problem, even if the data are sparsely sampled. We demonstrate the use of the method on both numerical and experimental data, showing that it is a successful mathematical architecture for characterizing the helicity injected torus with steady inductive (HIT-SI) magnetohydrodynamics. Importantly, the DMD produces interpretable, dominant mode structures, including a stationary mode consistent with our understanding of a HIT-SI spheromak accompanied by a pair of injector-driven modes. In combination, the 3-mode DMD model produces excellent dynamic reconstructions across the domain of analyzed data.

Effects of Kinetic Processes in Shaping Io's Global Plasma Environment: A 3D Hybrid Model

NASA Technical Reports Server (NTRS)

Lipatov, Alexander S.; Combi, Michael R.

2004-01-01

The global dynamics of the ionized and neutral components in the environment of Io plays an important role in the interaction of Jupiter's corotating magnetospheric plasma with Io. The stationary simulation of this problem was done in the MHD and the electrodynamics approaches. One of the main significant results from the simplified two-fluid model simulations was a production of the structure of the double-peak in the magnetic field signature of the I0 flyby that could not be explained by standard MHD models. In this paper, we develop a method of kinetic ion simulation. This method employs the fluid description for electrons and neutrals whereas for ions multilevel, drift-kinetic and particle, approaches are used. We also take into account charge-exchange and photoionization processes. Our model provides much more accurate description for ion dynamics and allows us to take into account the realistic anisotropic ion distribution that cannot be done in fluid simulations. The first results of such simulation of the dynamics of ions in the Io's environment are discussed in this paper.

Tritium retention in reduced-activation ferritic/martensitic steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hatano, Y.; Abe, S.; Matsuyama, M.

Reduced-activation ferritic/martensitic (RAFM) steels are structural material candidates for breeding blankets of future fusion reactors. Therefore, tritium (T) retention in RAFM steels is an important problem in assessing the T inventory of blankets. In this study, specimens of RAFM steels were subjected to irradiation of 20 MeV W ions to 0.54 displacements per atom (dpa), exposure to high flux D plasmas at 400 and 600 K and that to pulsed heat loads. The specimens thus prepared were exposed to DT gas at 473 K. Despite severe modification in the surface morphology, heat loads had negligible effects on T retention. Significantmore » increase in T retention at the surface and/or subsurface was observed after D plasma exposure. However, T trapped at the surface/subsurface layer was easily removed by maintaining the specimens in the air at about 300 K. Displacement damage led to increase in T retention in the bulk due to the trapping effects of defects, and T trapped was stable at 300 K. It was therefore concluded that displacement damages had the largest influence on T retention under the present conditions.« less

A spectral Poisson solver for kinetic plasma simulation

NASA Astrophysics Data System (ADS)

Szeremley, Daniel; Obberath, Jens; Brinkmann, Ralf

2011-10-01

Plasma resonance spectroscopy is a well established plasma diagnostic method, realized in several designs. One of these designs is the multipole resonance probe (MRP). In its idealized - geometrically simplified - version it consists of two dielectrically shielded, hemispherical electrodes to which an RF signal is applied. A numerical tool is under development which is capable of simulating the dynamics of the plasma surrounding the MRP in electrostatic approximation. In this contribution we concentrate on the specialized Poisson solver for that tool. The plasma is represented by an ensemble of point charges. By expanding both the charge density and the potential into spherical harmonics, a largely analytical solution of the Poisson problem can be employed. For a practical implementation, the expansion must be appropriately truncated. With this spectral solver we are able to efficiently solve the Poisson equation in a kinetic plasma simulation without the need of introducing a spatial discretization.

Simulations of the plasma dynamics in high-current ion diodes

NASA Astrophysics Data System (ADS)

Boine-Frankenheim, O.; Pointon, T. D.; Mehlhorn, T. A.

Our time-implicit fluid/Particle-In-Cell (PIC) code DYNAID [1]is applied to problems relevant for applied- B ion diode operation. We present simulations of the laser ion source, which will soon be employed on the SABRE accelerator at SNL, and of the dynamics of the anode source plasma in the applied electric and magnetic fields. DYNAID is still a test-bed for a higher-dimensional simulation code. Nevertheless, the code can already give new theoretical insight into the dynamics of plasmas in pulsed power devices.

The scaling of relativistic double-year widths - Poisson-Vlasov solutions and particle-in-cell simulations

NASA Technical Reports Server (NTRS)

Sulkanen, Martin E.; Borovsky, Joseph E.

1992-01-01

The study of relativistic plasma double layers is described through the solution of the one-dimensional, unmagnetized, steady-state Poisson-Vlasov equations and by means of one-dimensional, unmagnetized, particle-in-cell simulations. The thickness vs potential-drop scaling law is extended to relativistic potential drops and relativistic plasma temperatures. The transition in the scaling law for 'strong' double layers suggested by analytical two-beam models by Carlqvist (1982) is confirmed, and causality problems of standard double-layer simulation techniques applied to relativistic plasma systems are discussed.

Lattice Boltzmann method for weakly ionized isothermal plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Huayu; Ki, Hyungson

2007-12-15

In this paper, a lattice Boltzmann method (LBM) for weakly ionized isothermal plasmas is presented by introducing a rescaling scheme for the Boltzmann transport equation. Without using this rescaling, we found that the nondimensional relaxation time used in the LBM is too large and the LBM does not produce physically realistic results. The developed model was applied to the electrostatic wave problem and the diffusion process of singly ionized helium plasmas with a 1-3% degree of ionization under an electric field. The obtained results agree well with theoretical values.

Ring current dynamics and plasma sheet sources. [magnetic storms

NASA Technical Reports Server (NTRS)

Lyons, L. R.

1984-01-01

The source of the energized plasma that forms in geomagnetic storm ring currents, and ring current decay are discussed. The dominant loss processes for ring current ions are identified as charge exchange and resonant interactions with ion-cyclotron waves. Ring current ions are not dominated by protons. At L4 and energies below a few tens of keV, O+ is the most abundant ion, He+ is second, and protons are third. The plasma sheet contributes directly or indirectly to the ring current particle population. An important source of plasma sheet ions is earthward streaming ions on the outer boundary of the plasma sheet. Ion interactions with the current across the geomagnetic tail can account for the formation of this boundary layer. Electron interactions with the current sheet are possibly an important source of plasma sheet electrons.

a Case Study of Plasma Blob Associated with Plasma Bubble in Low Latitude Region in the Brazilian Sector Using All-Sky Images and DMSP Satellite

NASA Astrophysics Data System (ADS)

Tardelli, F. C.; Abalde, J. R.; Pimenta, A. A.; Kavutarapu, V.; Tardelli, A.

2016-12-01

Using optical techniques and satellite data a plasma blob case was observed on February 23, 2007, in São José dos Campos (SJC) (23.21°S, 45.86°O; dip. Lat. 17.6°S) in the Brazilian sector. This is the first observation of plasma blob in SJC region using data from optical techniques and satellite measurements. The plasma blob is the enhancements in plasma density by a factor of 2 or more above background plasma. Simultaneous all-sky images were used to map the spatial extent of plasma blob. DMSP satellite data were used to confirm the enhancements in plasma density in the ionosphere, which provides important parameters of the ionospheric behavior during the event. During the night of present study, the plasma blob was associated with a plasma bubble and the average zonal drift velocities are 61±6 m-s and 74±8 m-s, respectively. The average North/South and East/West extension of the blob were 591 km and 328 km, respectively. Furthermore, the average longitudinal drift velocity was 85±13 m-s. In this work plasma density is found to be enhanced by a factor of 2 compared to the background plasma. We report for the first time plasma blob in SJC at low latitude region associated with plasma bubble and present important features of their behavior.

Review of Plasma Techniques Used to Trap Antihydrogen

NASA Astrophysics Data System (ADS)

Fajans, Joel

2011-10-01

Recently, the ALPHA collaboration at CERN trapped antihydrogen atoms. To date, over three hundred antiatoms have been confined, some for as long as 1000s. This was the first time that antiatoms had ever been trapped. The ultimate goal of the ALPHA collaboration is to test CPT invariance by comparing the spectra of hydrogen and antihydrogen, and to measure the gravitational attraction between matter and antimatter. Such studies might resolve the baryogenesis problem: why is there very little antimatter in the Universe? The ALPHA experiment brought together techniques from many different fields of physics, but the crucial breakthroughs were in plasma physics. The essential problem is this: How does one combine two Malmberg-Penning trapped plasmas, one made from antiprotons, and the other positrons, which have opposite electrostatic potentials of nearly one volt, in such a manner that the antiprotons traverse the positrons with kinetic energies of less than 40 μeV, this latter being the depth of the superimposed neutral antihydrogen trap? The plasma techniques ALPHA developed to accomplish this include: Minimizing the effects of the neutral trap multipole fields on the positron and antiproton plasma confinement. Compressing antiprotons down to less than 0.5mm. Using autoresonance to inject antiprotons into the positrons with very little excess energy. Evaporative cooling of the electrons and antiprotons to record low temperatures. Development of charge, radial profile, temperature, and antiproton loss location diagnostics. Careful and lengthy manipulations to finesse the plasmas into the best states for optimal antihydrogen production and trapping. The plasma techniques necessary to trap antihydrogen will be reviewed in this talk. This work was supported by DOE and NSF, and is reported on behalf of the ALPHA collaboration.

Isomer and Fluorination Effects among Fluorine Substituted Hydrocarbon C3/C4 Molecules in Electron Impact Ionization

NASA Astrophysics Data System (ADS)

Patel, U. R.; Joshipura, K. N.

2015-05-01

Electron collision processes are very important in both man-made and natural plasmas, for determining the energy balances and transport properties of electrons. Electron -molecule scattering leading to ionization represents one of the most fundamental processes in collision physics. In the gas phase, the total efficiency of the process is described by the absolute total electron impact ionization cross section. Carbon based materials are some of the widely used materials for a divertor plate and magnetically confined fusion devices. In the ``ITER,'' it is very important for steady state operation to have an estimate of the lifetime of carbon plasma facing components. Apart from fusion plasma relevance, the present theoretical study is very important in modeling and controlling other electron assisted processes in many areas. Hydrocarbons play an important role for plasma diagnostics as impurities in the Tokamak fusion divertor, as seed gases for the production of radicals and ions in low temperature plasma processing. Fluorine substituted hydrocarbons (perfluorocarbons) are important as reactants in plasma assisted fabrication processes. In the present work, we have calculated total ionization cross sections Qion for C3/C4 Hydrocarbon isomers by electron impact, and comparisons are made mutually to observe isomer effect. Comparisons are also made by substituting H atom by F atom and revealing fluorination effect. The present calculations are quite significant owing to the lack of experimental data, with just an isolated previous theoretical work in some cases.

Research and Development of Large Area Color AC Plasma Displays

NASA Astrophysics Data System (ADS)

Shinoda, Tsutae

1998-10-01

Plasma display is essentially a gas discharge device using discharges in small cavities about 0. 1 m. The color plasma displays utilize the visible light from phosphors excited by the ultra-violet by discharge in contrast to monochrome plasma displays utilizing visible light directly from gas discharges. At the early stage of the color plasma display development, the degradation of the phosphors and unstable operating voltage prevented to realize a practical color plasma display. The introduction of the three-electrode surface-discharge technology opened the way to solve the problems. Two key technologies of a simple panel structure with a stripe rib and phosphor alignment and a full color image driving method with an address-and-display-period-separated sub-field method have realized practically available full color plasma displays. A full color plasma display has been firstly developed in 1992 with a 21-in.-diagonal PDP and then a 42-in.-diagonal PDP in 1995 Currently a 50-in.-diagonal color plasma display has been developed. The large area color plasma displays have already been put into the market and are creating new markets, such as a wall hanging TV and multimedia displays for advertisement, information, etc. This paper will show the history of the surface-discharge color plasma display technologies and current status of the color plasma display.

Microwave plasma source for neutral-beam injection systems

NASA Astrophysics Data System (ADS)

1981-08-01

The overall program is described and the technical and programmatic reasons for the decision to pursue both the RFI and ECH sources into the current hydrogen test stage is discussed. The general characteristics of plasma sources in the parameter regime of interest for neutral beam applications are considered. The operational characteristics, advantages and potential problems of RFI and ECH sources are discussed.

Automated divertor target design by adjoint shape sensitivity analysis and a one-shot method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dekeyser, W., E-mail: Wouter.Dekeyser@kuleuven.be; Reiter, D.; Baelmans, M.

As magnetic confinement fusion progresses towards the development of first reactor-scale devices, computational tokamak divertor design is a topic of high priority. Presently, edge plasma codes are used in a forward approach, where magnetic field and divertor geometry are manually adjusted to meet design requirements. Due to the complex edge plasma flows and large number of design variables, this method is computationally very demanding. On the other hand, efficient optimization-based design strategies have been developed in computational aerodynamics and fluid mechanics. Such an optimization approach to divertor target shape design is elaborated in the present paper. A general formulation ofmore » the design problems is given, and conditions characterizing the optimal designs are formulated. Using a continuous adjoint framework, design sensitivities can be computed at a cost of only two edge plasma simulations, independent of the number of design variables. Furthermore, by using a one-shot method the entire optimization problem can be solved at an equivalent cost of only a few forward simulations. The methodology is applied to target shape design for uniform power load, in simplified edge plasma geometry.« less

NASA's Technical Handbook for Avoiding On-Orbit ESD Anomalies Due to Internal Charging Effects

NASA Technical Reports Server (NTRS)

Whittlesey, Albert; Garrett, Henry B.

1996-01-01

This paper describes NASA-HDBK-4002, "Avoiding Problems Caused by Spacecraft On-Orbit Internal Charging Effects". The handbook includes a description of internal charging and why it is of concern to spacecraft designers. It also suggests how to determine when a project needs to consider internal spacecraft charging, it contains an electron penetration depth chart, rationale for a critical electron flux criterion, a worst-case geosynchronous electron plasma spectrum, general design guidelines, quantitative design guidelines, and a typical materials characteristics list. Appendices include a listing of some environment codes, electron transport codes, a discussion of geostationary electron plasma environments, a brief description of electron beam and other materials tests, and transient susceptibility tests. The handbook will be in the web page, hftp://standards.nasa.gov. A prior document, NASA TP2361 "Design Guidelines for Assessing and controlling Spacecraft Charging Effects", 1984, is in use to describe mitigation techniques for the effects of surface charging of satellites in space plasma environments. HDBK-4002 is meant to complement 2361 and together, the pair of documents describe both cause and mitigation designs for problems caused by energetic space plasmas.

Theory of interparticle correlations in dense, high-temperature plasmas. V - Electric and thermal conductivities

NASA Technical Reports Server (NTRS)

Ichimaru, S.; Tanaka, S.

1985-01-01

Ichimaru et al. (1985) have developed a general theory in which the interparticle correlations in dense, high-temperature multicomponent plasmas were formulated systematically over a wide range of plasma parameters. The present paper is concerned with an extension of this theory, taking into account the problems of the electronic transport in such high-density plasmas. It is shown that the resulting theory is capable of describing the transport coefficients accurately over a wide range of the density and temperature parameters. Attention is given to electric and thermal conductivities, generalized Coulomb logarithms, a comparison of the considered theory with other theories, and a comparison of the theory with experimental results.

Does Remuneration for Plasma Compromise Autonomy?

PubMed

White, Lucie

2015-12-01

In accordance with a recent statement released by the World Health Organization, the Canadian province of Ontario is moving to ban payment for plasma donation. This is partially based on contentions that remuneration for blood and blood products undermines autonomy and personal dignity. This paper is dedicated to evaluating this claim. I suggest that traditional autonomy-based arguments against commodification of human body parts and substances are less compelling in the context of plasma donation in Canada, but that there is another autonomy-based objection to paid plasma donation that has not received sufficient attention. Namely, the stigma that surrounds exchanging plasma for payment makes it difficult to make an autonomous decision to engage in this activity. I suggest that this problem can be overcome in one of two ways; by banning payment for plasma, or by reducing the stigma surrounding this practice. I provide an indication of how we might work to achieve the latter, contending that this possibility should be taken seriously, due to the difficulties in achieving a sufficient supply of plasma without remuneration.

Online plasma calculator

NASA Astrophysics Data System (ADS)

Wisniewski, H.; Gourdain, P.-A.

2017-10-01

APOLLO is an online, Linux based plasma calculator. Users can input variables that correspond to their specific plasma, such as ion and electron densities, temperatures, and external magnetic fields. The system is based on a webserver where a FastCGI protocol computes key plasma parameters including frequencies, lengths, velocities, and dimensionless numbers. FastCGI was chosen to overcome security problems caused by JAVA-based plugins. The FastCGI also speeds up calculations over PHP based systems. APOLLO is built upon the WT library, which turns any web browser into a versatile, fast graphic user interface. All values with units are expressed in SI units except temperature, which is in electron-volts. SI units were chosen over cgs units because of the gradual shift to using SI units within the plasma community. APOLLO is intended to be a fast calculator that also provides the user with the proper equations used to calculate the plasma parameters. This system is intended to be used by undergraduates taking plasma courses as well as graduate students and researchers who need a quick reference calculation.

The Effects of Ramadan Fasting on Body Composition, Blood Pressure, Glucose Metabolism, and Markers of Inflammation in NAFLD Patients: An Observational Trial.

PubMed

Aliasghari, Fereshteh; Izadi, Azimeh; Gargari, Bahram Pourghassem; Ebrahimi, Sara

2017-01-01

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease and is a serious global health problem. Regarding the increasing prevalence of NAFLD, finding various strategies to prevent and manage the disease is of great importance. The aim of this study was to determine the effects of caloric restriction during Ramadan fasting on anthropometric indices, fasting glucose, plasma insulin, insulin resistance, and inflammatory cytokines (C-reactive protein and interleukin 6) in patients with NAFLD. We conducted this study with 83 patients with NAFLD, 42 of whom decided to fast and 41 controls who decided not to fast for Ramadan, between June 18 and July 17, 2015. Anthropometric parameters were measured and a sample of venous blood was obtained for biochemical assays before and after Ramadan. There was a significant decrease in all anthropometric parameters as well as fasting glucose, plasma insulin, and insulin resistance. Relative to the nonfasting group, fasting significantly reduced circulating inflammatory, but changes in blood pressure after Ramadan were not significant. This study shows significant effects on parameters during Ramadan fasting such as anthropometric indices, fasting glucose, plasma insulin, and inflammatory cytokines in patients with NAFLD. The results of this study suggest that Ramadan fasting may be useful to improve NAFLD, so further studies are needed in this area.

Determination of Differential Emission Measure from Solar Extreme Ultraviolet Images

NASA Astrophysics Data System (ADS)

Su, Yang; Veronig, Astrid M.; Hannah, Iain G.; Cheung, Mark C. M.; Dennis, Brian R.; Holman, Gordon D.; Gan, Weiqun; Li, Youping

2018-03-01

The Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) has been providing high-cadence, high-resolution, full-disk UV-visible/extreme ultraviolet (EUV) images since 2010, with the best time coverage among all the solar missions. A number of codes have been developed to extract plasma differential emission measures (DEMs) from AIA images. Although widely used, they cannot effectively constrain the DEM at flaring temperatures with AIA data alone. This often results in much higher X-ray fluxes than observed. One way to solve the problem is by adding more constraint from other data sets (such as soft X-ray images and fluxes). However, the spatial information of plasma DEMs are lost in many cases. In this Letter, we present a different approach to constrain the DEMs. We tested the sparse inversion code and show that the default settings reproduce X-ray fluxes that could be too high. Based on the tests with both simulated and observed AIA data, we provided recommended settings of basis functions and tolerances. The new DEM solutions derived from AIA images alone are much more consistent with (thermal) X-ray observations, and provide valuable information by mapping the thermal plasma from ∼0.3 to ∼30 MK. Such improvement is a key step in understanding the nature of individual X-ray sources, and particularly important for studies of flare initiation.

New strategies of boar sperm cryopreservation: development of novel freezing and thawing methods with a focus on the roles of seminal plasma.

PubMed

Okazaki, Tetsuji; Shimada, Masayuki

2012-09-01

Cryopreservation of boar spermatozoa offers an effective means of long-term storage of important genetic material. Many researchers have investigated how to improve reproductive performance by artificial insemination (AI) using cryopreserved boar spermatozoa. Recently, we and other groups reported that high conception rates (70-80%) can be achieved by AI with frozen-thawed boar spermatozoa using a modified temperature program during freezing, or a novel cryopreservation extender to improve sperm quality (including sperm survivability, motility, membrane status and fertilization ability) after thawing, or a novel sperm infusion method, deep intra uterine insemination. However, these techniques have not yet been used for commercial pig production. The variation in sperm freezability among boars or among ejaculations in an identical boar is one of the main reasons for this problem. In our previous study, it was revealed that some components of seminal plasma have a negative effect on the freezability of boar sperm. One of these factors is bacteria-released endotoxin (lipopolysaccharide: LPS). LPS binds to Toll-like receptor-4 (TLR-4) expressed on the sperm surface, resulting in induction of apoptosis. On the other hand, seminal plasma suppresses cryo-capacitation induced by thawing stress. On the basis of these findings, we designed a novel protocol of AI using frozen-thawed boar sperm. © 2012 Japanese Society of Animal Science.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xian, Y. B.; Xu, H. T.; Lu, X. P., E-mail: luxinpei@hotmail.com

In this work, for better applications of atmospheric pressure plasma jets, the physics of plasma streamers in a glass tube with a part of it covered by a conductor is investigated. To better understand the propagation mechanism of plasma bullets in capillary tubes passing through a curved or narrow passage for some biomedical or material applications, the propagation of plasma streamers in a tube covered by a floating conductor is investigated. For a plasma streamer propagating in a tube covered by a conductor, the plasma streamer is suppressed and becomes shorter, and a secondary streamer is generated in the tubemore » at the downstream end of the conductor. The larger the area covered by the conductor, or the thinner the tube, the stronger the plasma streamer is inhibited. The electric potential of the conductor is measured to be as high as 6 kV. On the other hand, a higher voltage applied on the HV electrode, or a higher gas flow rate will make the secondary plasma streamer longer. It is found that the capacitor formed by the conductor outside the tube and the wall of the tube plays an important role in inhibiting the original plasma streamer and generating the secondary streamer. Moreover, the active species generated by the original plasma play important role in generating a secondary plasma streamer.« less

The Center for Multiscale Plasma Dynamics, Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gombosi, Tamas I.

The University of Michigan participated in the joint UCLA/Maryland fusion science center focused on plasma physics problems for which the traditional separation of the dynamics into microscale and macroscale processes breaks down. These processes involve large scale flows and magnetic fields tightly coupled to the small scale, kinetic dynamics of turbulence, particle acceleration and energy cascade. The interaction between these vastly disparate scales controls the evolution of the system. The enormous range of temporal and spatial scales associated with these problems renders direct simulation intractable even in computations that use the largest existing parallel computers. Our efforts focused on twomore » main problems: the development of Hall MHD solvers on solution adaptive grids and the development of solution adaptive grids using generalized coordinates so that the proper geometry of inertial confinement can be taken into account and efficient refinement strategies can be obtained.« less

Ponderomotive Forces in Cosmos

NASA Astrophysics Data System (ADS)

Lundin, R.; Guglielmi, A.

2006-12-01

This review is devoted to ponderomotive forces and their importance for the acceleration of charged particles by electromagnetic waves in space plasmas. Ponderomotive forces constitute time-averaged nonlinear forces acting on a media in the presence of oscillating electromagnetic fields. Ponderomotive forces represent a useful analytical tool to describe plasma acceleration. Oscillating electromagnetic fields are also related with dissipative processes, such as heating of particles. Dissipative processes are, however, left outside these discussions. The focus will be entirely on the (conservative) ponderomotive forces acting in space plasmas. The review consists of seven sections. In Section 1, we explain the rational for using the auxiliary ponderomotive forces instead of the fundamental Lorentz force for the study of particle motions in oscillating fields. In Section 2, we present the Abraham, Miller, Lundin-Hultqvist and Barlow ponderomotive forces, and the Bolotovsky-Serov ponderomotive drift. The hydrodynamic, quasi-hydrodynamic, and ‘`test-particle’' approaches are used for the study of ponderomotive wave-particle interaction. The problems of self-consistency and regularization are discussed in Section 3. The model of static balance of forces (Section 4) exemplifies the interplay between thermal, gravitational and ponderomotive forces, but it also introduces a set of useful definitions, dimensionless parameters, etc. We analyze the Alfvén and ion cyclotron waves in static limit with emphasis on the specific distinction between traveling and standing waves. Particular attention has been given to the impact of traveling Alfvén waves on the steady state anabatic wind that blows over the polar regions (Section~5). We demonstrate the existence of a wave-induced cold anabatic wind. We also show that, at a critical point, the ponderomotive acceleration of the wind is a factor of 3 greater than the thermal acceleration. Section 6 demonstrates various manifestations of ponderomotive forces in the Earth's magnetosphere, for instance the ionospheric plasma acceleration and outflow. The polar wind and the auroral density cavities are considered in relation to results from the Freja and Viking satellites. The high-altitude energization and escape of ions is discussed. The ponderomotive anharmonicity of standing Alfvén waves is analyzed from ground based ULF wave measurements. The complexity of the many challenging problems related with plasma processes near the magnetospheric boundaries is discussed in the light of recent Cluster observations. At the end of Section 6, we consider the application of ponderomotive forces to the diversity of phenomena on the Sun, in the interstellar environment, on newborn stars, pulsars and active galaxies. We emphasize the role of forcing of magnetized plasmas in general and ponderomotive forcing in particular, presenting some simple conceivable scenarios for massive outflow and jets from astrophysical objects.

Fundamental Processes in Partially Ionized Plasmas

DTIC Science & Technology

1988-08-01

thermal plasma chemistry , may significantly underestimate Lie importance of radiation losses. Also shown in Figure 4 are the earlier measurements of Emmons...in Thermal Plasma Chemistry ," 8th Int’l Symposium on Plasma Chemistry , Tokyo Japan, August 1987. 4. Kruger, Charles H., "Nonequilibrium Effects in...Annual Gaseous Electronics Conference, Minneapolis, MN, October 1988. 7. Kruger, C. H., "Nonequilibrium Effects in Thermal Plasma Chemistry ," Submitted

Diffraction of dust acoustic waves by a circular cylinder

NASA Astrophysics Data System (ADS)

Kim, S.-H.; Heinrich, J. R.; Merlino, R. L.

2008-09-01

The diffraction of dust acoustic (DA) waves around a long dielectric rod is observed using video imaging methods. The DA waves are spontaneously excited in a dusty plasma produced in a direct current glow discharge plasma. The rod acquires a negative charge that produces a coaxial dust void around it. The diameter of the void is the effective size of the "obstacle" encountered by the waves. The wavelength of the DA waves is approximately the size of the void. The observations are considered in relation to the classical problem of the diffraction of sound waves from a circular cylinder, a problem first analyzed by Lord Rayleigh [Theory of Sound, 2nd ed. (MacMillan, London, 1896)].

Fusion power for space propulsion.

NASA Technical Reports Server (NTRS)

Roth, R.; Rayle, W.; Reinmann, J.

1972-01-01

Principles of operation, interplanetary orbit-to-orbit mission capabilities, technical problems, and environmental safeguards are examined for thermonuclear fusion propulsion systems. Two systems examined include (1) a fusion-electric concept in which kinetic energy of charged particles from the plasma is converted into electric power (for accelerating the propellant in an electrostatic thrustor) by the van de Graaf generator principle and (2) the direct fusion rocket in which energetic plasma lost from the reactor has a suitable amount of added propellant to obtain the optimum exhaust velocity. The deuterium-tritium and the deuterium/helium-3 reactions are considered as suitable candidates, and attention is given to problems of cryogenic refrigeration systems, magnet shielding, and high-energy particle extraction and guidance.

Multi-Objective Scheduling for the Cluster II Constellation

NASA Technical Reports Server (NTRS)

Johnston, Mark D.; Giuliano, Mark

2011-01-01

This paper describes the application of the MUSE multiobjecctive scheduling framework to the Cluster II WBD scheduling domain. Cluster II is an ESA four-spacecraft constellation designed to study the plasma environment of the Earth and it's magnetosphere. One of the instruments on each of the four spacecraft is the Wide Band Data (WBD) plasma wave experiment. We have applied the MUSE evolutionary algorithm to the scheduling problem represented by this instrument, and the result has been adopted and utilized by the WBD schedulers for nearly a year. This paper describes the WBD scheduling problem, its representation in MUSE, and some of the visualization elements that provide insight into objective value tradeoffs.

Platelet-rich plasma: combinational treatment modalities for musculoskeletal conditions.

PubMed

Andia, Isabel; Abate, Michele

2018-04-01

Current research on common musculoskeletal problems, including osteoarticular conditions, tendinopathies, and muscle injuries, focuses on regenerative translational medicine. Platelet-rich plasma therapies have emerged as a potential approach to enhance tissue repair and regeneration. Platelet-rich plasma application aims to provide supraphysiological concentrations of platelets and optionally leukocytes at injured/pathological tissues mimicking the initial stages of healing. However, the efficacy of platelet-rich plasma is controversial in chronic diseases because patients' outcomes show partial improvements. Platelet-rich plasma can be customized to specific conditions by selecting the most appropriate formulation and timing for application or by combining platelet-rich plasma with synergistic or complementary treatments. To achieve this goal, researchers should identify and enhance the main mechanisms of healing. In this review, the interactions between platelet-rich plasma and healing mechanisms were addressed and research opportunities for customized treatment modalities were outlined. The development of combinational platelet-rich plasma treatments that can be used safely and effectively to manipulate healing mechanisms would be valuable and would provide insights into the processes involved in physiological healing and pathological failure.

Invention of the Annular Inductively Coupled Plasma as a Spectroscopic Source

NASA Astrophysics Data System (ADS)

Greenfield, Stanley

2000-05-01

This paper shows how experiments with electrical discharges from the 18th century onward led to their use as sources in atomic spectroscopy and how the invention of the annular inductively coupled plasma (ICP) some 30 years ago arose from the need to solve a problem that necessitated the use of a high-temperature source. The search for such a source followed a fairly logical pattern involving dc plasma jets and an ICP such as had been used by T. B. Reed for crystal growing. The ellipsoidal plasma used by Reed was not entirely suitable as a spectroscopic source, since the analytical sample either mixed with the plasma gases or passed around the plasma, resulting in matrix effects and a diminution in the emission. It is shown how suitable modification of the plasma torch with attention to gas flows made it possible to produce an annular or tunnel plasma through which the sample aerosol could be passed, resulting in an annular ICP with greatly improved spectroscopic properties. The further refinements to the source and ancillary equipment are also discussed.

Hybrid simulations of weakly collisional plasmas

NASA Astrophysics Data System (ADS)

Xia, Qian; Reville, Brian; Tzoufras, Michail

2016-10-01

Laser produced plasma experiments can be exploited to investigate phenomena of astrophysical relevance. The high densities and velocities that can be generated in the laboratory provide ideal conditions to investigate weakly collisional or collisionless plasma shock physics. In addition, the high temperatures permit magnetic and kinetic Reynolds numbers that are difficult to achieve in other plasma experiments, opening the possibility to study plasma dynamo. Many of these experiments are based on a classic plasma physics problem, namely the interpenetration of two plasma flows. To investigate this phenomenon, we are constructing a novel multi-dimensional hybrid numerical scheme, that solves the ion distribution kinetically via a Vlasov-Fokker-Planck equation, with electrons providing a charge neutralizing fluid. This allows us to follow the evolution on hydrodynamic timescales, while permitting inclusion ofcollisionlesseffects on small scales. It also could be used to study the increasing collisional effects due to the stiff gradient and weakly anisotropic velocity distribution. We present some preliminary validation tests for the code, demonstrating its ability to accurately model key processes that are relevant to laboratory and astrophysical plasmas.

Use of a "Super-child" Approach to Assess the Vitamin A Equivalence of Moringa oleifera Leaves, Develop a Compartmental Model for Vitamin A Kinetics, and Estimate Vitamin A Total Body Stores in Young Mexican Children.

PubMed

Lopez-Teros, Veronica; Ford, Jennifer Lynn; Green, Michael H; Tang, Guangwen; Grusak, Michael A; Quihui-Cota, Luis; Muzhingi, Tawanda; Paz-Cassini, Mariela; Astiazaran-Garcia, Humberto

2017-12-01

Background: Worldwide, an estimated 250 million children <5 y old are vitamin A (VA) deficient. In Mexico, despite ongoing efforts to reduce VA deficiency, it remains an important public health problem; thus, food-based interventions that increase the availability and consumption of provitamin A-rich foods should be considered. Objective: The objectives were to assess the VA equivalence of 2 H-labeled Moringa oleifera (MO) leaves and to estimate both total body stores (TBS) of VA and plasma retinol kinetics in young Mexican children. Methods: β-Carotene was intrinsically labeled by growing MO plants in a 2 H 2 O nutrient solution. Fifteen well-nourished children (17-35 mo old) consumed puréed MO leaves (1 mg β-carotene) and a reference dose of [ 13 C 10 ]retinyl acetate (1 mg) in oil. Blood (2 samples/child) was collected 10 times (2 or 3 children each time) over 35 d. The bioefficacy of MO leaves was calculated from areas under the composite "super-child" plasma isotope response curves, and MO VA equivalence was estimated through the use of these values; a compartmental model was developed to predict VA TBS and retinol kinetics through the use of composite plasma [ 13 C 10 ]retinol data. TBS were also estimated with isotope dilution. Results: The relative bioefficacy of β-carotene retinol activity equivalents from MO was 28%; VA equivalence was 3.3:1 by weight (0.56 μmol retinol:1 μmol β-carotene). Kinetics of plasma retinol indicate more rapid plasma appearance and turnover and more extensive recycling in these children than are observed in adults. Model-predicted mean TBS (823 μmol) was similar to values predicted using a retinol isotope dilution equation applied to data from 3 to 6 d after dosing (mean ± SD: 832 ± 176 μmol; n = 7). Conclusions: The super-child approach can be used to estimate population carotenoid bioefficacy and VA equivalence, VA status, and parameters of retinol metabolism from a composite data set. Our results provide initial estimates of retinol kinetics in well-nourished young children with adequate VA stores and demonstrate that MO leaves may be an important source of VA. © 2017 American Society for Nutrition.

Planetary rings as relics of plasma proto-rings rotating in the magnetic field of a central body

NASA Astrophysics Data System (ADS)

Rabinovich, B.

2007-08-01

A possibility is discussed in accordance to hypothesis by H. Alfven, that the rings of large planets are relics of some plasma proto-rings rotating in the magnetic fields of central bodies. A finite-dimensional mathematical model of the system is synthesized using the solution of the boundary-value problem by the Boubnov - Galerkin method. The dipole magnetic field of the central body is assumed to have a small eccentricity, and the dipole axis - to be inclined at a small angle to the central body's axis of rotation which coincides with the ring's rotation axis. The proto-ring is supposed to be thin and narrow and having the same rotating axis as the central body. A medium forming the ring is cold rarefied plasma with high electron density, so that electric conductivity of the medium tends to infinity, as well as the magnetic Reynolds number. The original mathematical model is reduced to a system of finite-difference equations whose asymptotic analytical solution is obtained. Emphasis is placed on the problems of stability of the ring's steady state rotation and quantization of the eigenvalues of nondimensional sector velocity of the ring with respect to the central body. The solutions corresponding to magneto-gravitational and to magneto-gyroscopic waves are considered It is demonstrated that some rings characterized by integral quantum numbers are stable and long-living, while the rings which are associated with half-integer quantum numbers () are unstable and short-living. As a result, an evolutionally rife rotating plasma ring turns out to be stratified into a large number of narrow elite rings separated by gaps whose position correspond to anti-rings. The regions of possible existence of elite rings in near-central body space are determined. The main result of eigenvalue spectrum's analysis is as follows. Quantum numbers determining elite eigenvalues of the sector velocity of a ring (normalized in a certain manner) coincide with the quantum numbers appearing in the solution of the Schr¨odingerequation for a hydrogen atom. Perturbations of the elite orbits corresponding to this numbers satisfy the de Brogli quantum-mechanical condition. The solution of the model boundary-value problem has been applied to planetary rings origin and evolution. The main result is a mechanism of stratification of the evolutionally mature plasma proto-ring into a large number of narrow elite rings separated by anti-rings (gaps), which were playing a role of for present-day planetary rings. Another result is the theoretical substantiation of the presence in the nearplanetary space of a region of existence and stability of plasma rings. The data, which had been obtained in the course of the Voyager, Galileo, and Cassini missions were used for verification of theoretical results concerning the planetary rings and Io plasma thorus. The theoretical dates turned out to be in accordance with experimental dates. References Alfven H. Cosmic Plasma. Dordrecht: Reidel, 1961. Rabinovich B.I. Dynamics of Plasma Ring Rotating in the Magnetic Field of Central Body: Magneto-GravitationalWaves // Cosmic Research, 2006. V. 44. No. 1. P. 43-51. Rabinovich B.I. Dynamics of Plasma Ring Rotating in the Magnetic Field of Central Body: Magneto-Gyroscopic Waves. Problems of Stability and Quantization // Cosmic Research, 2006. V. 44. No. 2. P. 146 - 161. Gore, Rick. Voyager 1 at Saturn. Riddles of the Rings // National Geographic, 1981. V. 160. No. 1. P. 3 - 31. Porco, Carolyn. Captain 's Log.: 2004, 184 // The Planetary Report, 2004. V. 24, No. 5. P. 2 - 18.

Heat flux viscosity in collisional magnetized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C., E-mail: cliu@pppl.gov; Fox, W.; Bhattacharjee, A.

2015-05-15

Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through themore » generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.« less

Optimal control of a coupled partial and ordinary differential equations system for the assimilation of polarimetry Stokes vector measurements in tokamak free-boundary equilibrium reconstruction with application to ITER

NASA Astrophysics Data System (ADS)

Faugeras, Blaise; Blum, Jacques; Heumann, Holger; Boulbe, Cédric

2017-08-01

The modelization of polarimetry Faraday rotation measurements commonly used in tokamak plasma equilibrium reconstruction codes is an approximation to the Stokes model. This approximation is not valid for the foreseen ITER scenarios where high current and electron density plasma regimes are expected. In this work a method enabling the consistent resolution of the inverse equilibrium reconstruction problem in the framework of non-linear free-boundary equilibrium coupled to the Stokes model equation for polarimetry is provided. Using optimal control theory we derive the optimality system for this inverse problem. A sequential quadratic programming (SQP) method is proposed for its numerical resolution. Numerical experiments with noisy synthetic measurements in the ITER tokamak configuration for two test cases, the second of which is an H-mode plasma, show that the method is efficient and that the accuracy of the identification of the unknown profile functions is improved compared to the use of classical Faraday measurements.

Design of a tokamak fusion reactor first wall armor against neutral beam impingement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, R.A.

1977-12-01

The maximum temperatures and thermal stresses are calculated for various first wall design proposals, using both analytical solutions and the TRUMP and SAP IV Computer Codes. Beam parameters, such as pulse time, cycle time, and beam power, are varied. It is found that uncooled plates should be adequate for near-term devices, while cooled protection will be necessary for fusion power reactors. Graphite and tungsten are selected for analysis because of their desirable characteristics. Graphite allows for higher heat fluxes compared to tungsten for similar pulse times. Anticipated erosion (due to surface effects) and plasma impurity fraction are estimated. Neutron irradiationmore » damage is also discussed. Neutron irradiation damage (rather than erosion, fatigue, or creep) is estimated to be the lifetime-limiting factor on the lifetime of the component in fusion power reactors. It is found that the use of tungsten in fusion power reactors, when directly exposed to the plasma, will cause serious plasma impurity problems; graphite should not present such an impurity problem.« less

Studies on the transmission of sub-THz waves in magnetized inhomogeneous plasma sheath

NASA Astrophysics Data System (ADS)

Yuan, Kai; Shen, Linfang; Yao, Ming; Deng, Xiaohua; Chen, Zhou; Hong, Lujun

2018-01-01

There have been many studies on the sub-terahertz (sub-THz) wave transmission in reentry plasma sheaths. However, only some of them have paid attention to the transmission of sub-THz waves in magnetized plasma sheaths. In this paper, the transmission of sub-THz waves in both unmagnetized and magnetized reentry plasma sheaths was investigated. The impacts of temporal evolution of the plasma sheath on the wave transmission were studied. The transmission of "atmospheric window" frequencies in a magnetized plasma sheath was discussed in detail. According to the study, the power transmission rates (Tp) for the left hand circular (LHC) and the right hand circular modes in the magnetized plasma sheath are obviously higher and lower than those in the unmagnetized plasma sheath, respectively. The Tp of LHC mode increases with both wave frequency and external magnetic field strength. Also, the Tp of LHC mode in both magnetized and unmagnetized plasma sheaths varies with time due to the temporal evolution of the plasma sheath. Moreover, the performance of sub-THz waves in magnetized plasma sheath hints at a new approach to the "blackout" problem. The new approach, which is in the capability of modern technology, is to utilize the communication system operating at 140 GHz with an onboard magnet installed near the antenna.

TOPICA/TORIC integration for self-consistent antenna and plasma analysis

NASA Astrophysics Data System (ADS)

Maggiora, Riccardo; Lancellotti, Vito; Milanesio, Daniele; Kyrytsya, Volodymyr; Vecchi, Giuseppe; Bonoli, Paul T.; Wright, John C.

2006-10-01

TOPICA [1] is a numerical suite conceived for prediction and analysis of plasma-facing antennas. It can handle real-life 3D antenna geometries (with housing, Faraday screen, etc.) as well as a realistic plasma model, including measured density and temperature profiles. TORIC [2] solves the finite Larmor radius wave equations in the ICRF regime in arbitrary axisymmetric toroidal plasmas. Due to the approach followed in developing TOPICA (i.e. the formal splitting of the problem in the vacuum region around the antenna and the plasma region inside the toroidal chamber), the code lends itself to handle toroidal plasmas, provided TORIC is run independently to yield the plasma surface admittance tensorsY (m,m',n). The latter enter directly into the integral equations solved by TOPICA, thus allowing a far more accurate plasma description that accounts for curvature effects. TOPICA outputs comprise, among others, the EM fields in front of the plasma: these can in turn be input to TORIC, in order to self-consistently determine the EM field propagation in the plasma. In this work, we report on the theory underlying the TOPICA/TORIC integration and the ongoing evolution of the two codes. [1] V. Lancellotti et al., Nucl. Fusion, 46 (2006) S476 [2] M. Brambilla, Plasma Phys. Contr. Fusion (1999) 41 1

Plasma Diagnostics: Use and Justification in an Industrial Environment

NASA Astrophysics Data System (ADS)

Loewenhardt, Peter

1998-10-01

The usefulness and importance of plasma diagnostics have played a major role in the development of plasma processing tools in the semiconductor industry. As can be seen through marketing materials from semiconductor equipment manufacturers, results from plasma diagnostic equipment can be a powerful tool in selling the technological leadership of tool design. Some diagnostics have long been used for simple process control such as optical emission for endpoint determination, but in recent years more sophisticated and involved diagnostic tools have been utilized in chamber and plasma source development and optimization. It is now common to find an assortment of tools at semiconductor equipment companies such as Langmuir probes, mass spectrometers, spatial optical emission probes, impedance, ion energy and ion flux probes. An outline of how the importance of plasma diagnostics has grown at an equipment manufacturer over the last decade will be given, with examples of significant and useful results obtained. Examples will include the development and optimization of an inductive plasma source, trends and hardware effects on ion energy distributions, mass spectrometry influences on process development and investigations of plasma-wall interactions. Plasma diagnostic focus, in-house development and proliferation in an environment where financial justification requirements are both strong and necessary will be discussed.

Conceptual study of an ICRH traveling-wave antenna system for low-coupling conditions as expected in DEMO

NASA Astrophysics Data System (ADS)

Ragona, R.; Messiaen, A.

2016-07-01

For the central heating of a fusion reactor ion cyclotron radio frequency heating (ICRH) is the first choice method as it is able to couple RF power to the ions without density limit. The drawback of this heating method is the problem of excitation of the magneto-sonic wave through the plasma boundary layer from the antenna located along the wall, without exceeding its voltage standoff. The amount of coupling depends on the antenna excitation and the surface admittance at the antenna output due to the plasma profile. The paper deals with the optimization of the antenna excitation by the use of sections of traveling-wave antennas (TWAs) distributed all along the reactor wall between the blanket modules. They are mounted and fed in resonant ring system(s). First, the physics of the coupling of a strap array is studied by simple models and the coupling code ANTITER II. Then, after the study of the basic properties of a TWA section, its feeding problem is solved by hybrids driving them in resonant ring circuit(s). The complete modeling is obtained from the matrices of the TWA sections connected to one of the feeding hybrid(s). The solution is iterated with the coupling code to determine the loading for a reference low-coupling ITER plasma profile. The resulting wave pattern up to the plasma bulk is derived. The proposed system is totally load resilient and allows us to obtain a very selective exciting wave spectrum. A discussion of some practical implementation problems is added.

The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

NASA Astrophysics Data System (ADS)

Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

2018-01-01

Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence seismology.

Numerical calculation of ion runaway distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Embréus, O.; Stahl, A.; Hirvijoki, E.

2015-05-15

Ions accelerated by electric fields (so-called runaway ions) in plasmas may explain observations in solar flares and fusion experiments; however, limitations of previous analytic work have prevented definite conclusions. In this work, we describe a numerical solver of the 2D non-relativistic linearized Fokker-Planck equation for ions. It solves the initial value problem in velocity space with a spectral-Eulerian discretization scheme, allowing arbitrary plasma composition and time-varying electric fields and background plasma parameters. The numerical ion distribution function is then used to consider the conditions for runaway ion acceleration in solar flares and tokamak plasmas. Typical time scales and electric fieldsmore » required for ion acceleration are determined for various plasma compositions, ion species, and temperatures, and the potential for excitation of toroidal Alfvén eigenmodes during tokamak disruptions is considered.« less

The Experimental Study of Novel Pseudospark Hollow Cathode Plasma Electron Gun

NASA Astrophysics Data System (ADS)

Gu, Xiaowei; Meng, Lin; Sun, Yiqin; Yu, Xinhua

2008-11-01

The high-power microwave devices with plasma-filled have unique properties. One of the major problems associated with plasma-filled microwave sources is that ions from the plasma drift toward the gun regions of the tube. This bombardment is particularly dangerous for the gun, where high-energy ion impacts can damage the cathode surface and degrade its electron emission capabilities. One of the techniques investigated to mitigate this issue is to replace the material cathode with plasma cathode. Now, we study the novel electron gun (E-gun) that can be suitable for high power microwave device applications, adopting two forms of discharge channel, 1: a single hole channel, the structure can produce a solid electron beam; 2: porous holes channel, the structure can generate multiple electronic injection which is similar to the annular electron beam.

Jupiter Data Analysis Program: Analysis of Voyager wideband plasma wave observations

NASA Technical Reports Server (NTRS)

Kurth, W. S.

1983-01-01

Voyager plasma wave wideband frames from the Jovian encounters are analyzed. The 511 frames which were analyzed were chosen on the basis of low-rate spectrum analyzer data from the plasma wave receiver. These frames were obtained in regions and during times of various types of plasma or radio wave activity as determined by the low-rate, low-resolution data and were processed in order to provide high resolution measurements of the plasma wave spectrum for use in the study of a number of outstanding problems. Chorus emissions at Jupiter were analyzed. The detailed temporal and spectral form of the very complex chorus emissions near L = 8 on the Voyager 1 inbound passage was compared to both terrestrial chorus emissions as well as to the theory which was developed to explain the terrestrial waves.

Solitary plasma rings and magnetic field generation involving gravity and differential rotation

NASA Astrophysics Data System (ADS)

Coppi, B.

2012-12-01

A new theoretical framework for describing how magnetic fields are generated and amplified is provided by finding magneto-gravitational modes that involve gravity, density gradients, and differential rotation in an essential way. Other factors, such as the presence of a high temperature particle population or of a temperature gradient, can contribute to their excitation. These modes identified by a linearized analysis are shown to be important for the evolution of plasma disks surrounding black holes toward different configurations. Since the nonlinear development of these modes can lead to radially localized regions with a relatively small differential rotation, new stationary structures have been identified, in the (fully) nonlinear limit, which are localized radially over regions with negligible gradients of the rotation frequency. These structures, characterized by solitary plasma rings, do not involve a pre-existing "seed" magnetic field, unlike other configurations found previously. The relevant magnetic energy density is comparable to the gravitationally confined plasma pressure. The "source" of these configurations is the combination of the gravitational force and of the plasma density gradient orthogonal to it that is an important factor in the theory of magneto-gravitational modes, another important factor being an anisotropy of the plasma pressure.

Dynamics of a plasma ring rotating in the magnetic field of a central body: Magneto-gravitational waves

NASA Astrophysics Data System (ADS)

Rabinovich, B. I.

2006-01-01

The model problem of the dynamics of a planar plasma ring rotating in the dipole magnetic field of a central body is considered. A finite-dimensional mathematical model of the system is synthesized by the Boubnov-Galerkin method. The class of solutions corresponding to magneto-gravitational waves associated with deformations of the ring boundaries is investigated.

Entropy production during hadronization of a quark-gluon plasma

NASA Astrophysics Data System (ADS)

Biró, Tamás S.; Schram, Zsolt; Jenkovszky, László

2018-02-01

We revisit some physical pictures for the hadronization of quark-gluon plasma, concentrating on the problem of entropy production during processes where the number of degrees of freedom is seemingly reduced due to color confinement. Based on observations on Regge trajectories we propose not having an infinite tower of hadronic resonances. We discuss possible entropy production mechanisms far from equilibrium in terms of stochastic dynamics.

On Coulomb collisions in the solar wind

NASA Astrophysics Data System (ADS)

Hellinger, P.; Travnicek, P. M.

2009-04-01

Collisional transport in anisotropic plasmas is investigated comparing theoretical predictions of the Fokker-Planck equation for bi-Maxwellian particle distribution functions (Kogan, 1961; Lehner, 1967) and results of the corresponding Langevin equation. References: Kogan, V. I., in Plasma Physics and the Problem of Controlled Thermonuclear Reactions, edited by M. A. Leontovich, Pergamon Press, New York, , vol. 1, 153, 1961. Lehner, G., Zeitschrift fur Physik, 206, 284, 1967.

Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

DTIC Science & Technology

2012-10-01

cut fruit surfaces contaminated with migrating microorganisms," Journal of Food Protection, vol. 71, pp. 1619-1625, Aug 2008. [31] H. L. Chen, et...foodborne and opportunistic nosocomial pathogens is a major problem in food industry, biomedical and hospital applications, respectively. The resistive...source is very efficient in decontaminating wide range of infection and contamination causing bacteria. The direct and indirect exposure of the RBP

Atmospheric pressure plasma jet for biomedical applications characterised by passive thermal probe

NASA Astrophysics Data System (ADS)

Mance, Diana; Wiese, Ruben; Kewitz, Thorben; Kersten, Holger

2018-05-01

Atmospheric pressure plasma jets (APPJs) are a promising tool in medicine with extensive possibilities of utilization. For a safe and therapeutically effective application of APPJs, it is necessary to know in detail the physical processes in plasma as well as possible hazards. In this paper, we focus on plasma thermal energy transferred to the substrate, i.e. to a passive thermal probe acting as substrate dummy. Specifically, we examined the dependence of transferred energy on the distance from the plasma source outlet, on the gas flow rate, and on the length of the visible plasma plume. The plasma plume is the plasma carried by the gas flow from the outlet of the source into the ambient air. The results show the distance between the plasma-generating device and the substrate to be the most important determinant of the transferred thermal energy, among the three examined variables. Most importantly for the end-user, the results also show this relation to be non-linear. To describe this relation, we chose a model based on a Boltzmann type of sigmoid function. Based on the results of our modelling and visual inspection of the plasma, we provide sort of a user guide for the adjustment of a suitable energy flux on the (bio) substrate.

Ultra-Sensitive Elemental Analysis Using Plasmas 3.For Understanding an Inductively Coupled Plasma Mass Spectrometer

NASA Astrophysics Data System (ADS)

Sakata, Kenichi

Aplasma-interface is considered the most mysterious part of an inductively coupled plasma mass spectrometer system in terms of understanding its operational mechanism. After a brief explanation of the basic structure of the inductively coupled plasma mass spectrometer and how it works, the plasma-interface is discussed in regard to its complex operation and approaches to investigating its behavior. In particular, the position and shape of the plasma boundary seem to be important to understand the instrument's sensitivity.

Studies of Particle Acceleration, Transport and Radiation in Impulsive Phase of Solar Flares

NASA Technical Reports Server (NTRS)

Petrosian, Vahe

2005-01-01

Solar activity and its most prominent aspect, the solar flares, have considerable influence on terrestrial and space weather. Solar flares also provide a suitable laboratory for the investigation of many plasma and high energy processes important in the magnetosphere of the Earth and many other space and astrophysical situations. Hence, progress in understanding of flares will have considerable scientific and societal impact. The primary goal of this grant is the understanding of two of the most important problems of solar flare physics, namely the determination of the energy release mechanism and how this energy accelerates particles. This is done through comparison of the observations with theoretical models, starting from observations and gradually proceeding to theoretically more complex situations as the lower foundations of our understanding are secured. It is generally agreed that the source of the flare energy is the annihilation of magnetic fields by the reconnection process. Exactly how this energy is released or how it is dissipated remains controversial. Moreover, the exact mechanism of the acceleration of the particles is still a matter of debate. Data from many spacecrafts and ground based instruments obtained over the past decades have given us some clues. Theoretical analyses of these data have led to the standard thick target model (STT) where most of the released energy goes into an (assumed) power law spectrum of accelerated particles, and where all the observed radiations are the consequence of the interaction of these particles with the flare plasma. However, some theoretical arguments, and more importantly some new observations, have led us to believe that the above picture is not complete. It appears that plasma turbulence plays a more prominent role than suspected previously, and that it is the most likely agent for accelerating particles. The model we have developed is based on production of a high level of plasma waves and turbulence in the reconnection region above a flare loop. This turbulence accelerates particles stochastically which radiate some of their energy in this region but carry most of their energy to the footpoints of the loop, where they lose all their energy and radiate bulk of the observed radiation as in the traditional thick target model. In the past we have worked on various aspects of this model. We have evaluated the interaction rates of the plasma waves with electrons and ions, developed theoretical frameworks for the acceleration, transport and radiative processes, and produced numerical codes for the investigation of these processes. The goal of this grant has been further development and testing of this new paradigm, with emphases on the relative acceleration of electrons and ions and on a comprehensive investigation of the turbulence generation, cascade, and damping processes. We review several pieces of important evidence that we have uncovered indicating the crucial roles of turbulence, in and we describe accomplishments during the past two years of this grant.

Via fill properties of organic BARCs in dual-damascene application

NASA Astrophysics Data System (ADS)

Huang, Runhui

2004-05-01

With the introduction of copper as the interconnect metal, the Dual Damascene (DD) process has been integrated into integrated circuit (IC) device fabrication. The DD process utilizes organic bottom anti-reflective coatings (BARCs) not only to eliminate the thin film interference effects but also to act as via fill materials. However, three serious processing problems are encountered with organic BARCs. One is the formation of voids, which are trapped gas bubbles (evaporating solvent, byproduct of the curing reaction and air) inside the vias. Another problem is non-uniform BARC layer thickness in different via pitch areas. The third problem is the formation of fences during plasma etch. Fences are formed from materials that are removed by plasma and subsequently deposited on the sidewall surrounding the via openings during the etching process. Voids can cause variations in BARC top thickness, optical properties, via fill percentage, and plasma etch rate. This study focuses on the factors that influence the formation of voids and addresses the ways to eliminate them by optimizing the compositions of formulations and the processing conditions. Effects of molecular weight of the polymer, nature of the crosslinker, additives, and bake temperature were examined. The molecular weight of the polymer is one of the important factors that needs to be controlled carefully. Polymers with high molecular weights tend to trap voids inside the vias. Low molecular weight polymers have low Tg and low viscosity, which enables good thermal flow so that the BARC can fill vias easily without voids. Several kinds of crosslinkers were investigated in this study. When used with the same polymer system, formulations with different crosslinkers show varying results that affect planar fill, sidewall coverage, and, in some cases, voids. Additives also can change via fill behavior dramatically, and choosing the right additive will improve the via fill property. Processing conditions such as bake temperature also greatly affect via fill. Depending on the polymer thermal property and crosslinking reaction, varying the bake temperature can change the via fill behavior of the BARC. By understanding the nature of the polymer, the crosslinking reaction, and the processing conditions, we are able to design BARCs with better flow property to provide planar topography without voids inside the vias.

Kinetic Modeling of Next-Generation High-Energy, High-Intensity Laser-Ion Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albright, Brian James; Yin, Lin; Stark, David James

One of the long-standing problems in the community is the question of how we can model “next-generation” laser-ion acceleration in a computationally tractable way. A new particle tracking capability in the LANL VPIC kinetic plasma modeling code has enabled us to solve this long-standing problem

Waves in space plasma dipole antenna subsystem

NASA Technical Reports Server (NTRS)

Thomson, Mark

1993-01-01

The Waves In Space Plasma (WISP) flight experiment requires a 50-meter-long deployable dipole antenna subsystem (DASS) to radiate radio frequencies from the STS Orbiter cargo bay. The transmissions are to excite outer ionospheric plasma between the dipole and a free-flying receiver (Spartan) for scientific purposes. This report describes the singular DASS design requirements and how the resulting design satisfies them. A jettison latch is described in some detail. The latch releases the antenna in case of any problems which might prevent the bay doors from closing for re-entry and landing of the Orbiter.

Comment on “Surface electromagnetic wave equations in a warm magnetized quantum plasma” [Phys. Plasmas 21, 072114 (2014)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moradi, Afshin, E-mail: a.moradi@kut.ac.ir

2016-07-15

In a recent article [C. Li et al., Phys. Plasmas 21, 072114 (2014)], Li et al. studied the propagation of surface waves on a magnetized quantum plasma half-space in the Voigt configuration (in this case, the magnetic field is parallel to the surface but is perpendicular to the direction of propagation). Here, we present a fresh look at the problem and obtain a new form of dispersion relation of surface waves of the system. We find that our new dispersion relation does not agree with the result obtained by Li et al.

3D model of filler melting with micro-beam plasma arc based on additive manufacturing technology

NASA Astrophysics Data System (ADS)

Chen, Weilin; Yang, Tao; Yang, Ruixin

2017-07-01

Additive manufacturing technology is a systematic process based on discrete-accumulation principle, which is derived by the dimension of parts. Aiming at the dimension mathematical model and slicing problems in additive manufacturing process, the constitutive relations between micro-beam plasma welding parameters and the dimension of part were investigated. The slicing algorithm and slicing were also studied based on the dimension characteristics. By using the direct slicing algorithm according to the geometric characteristics of model, a hollow thin-wall spherical part was fabricated by 3D additive manufacturing technology using micro-beam plasma.

Ion-acoustic double-layers in a magnetized plasma with nonthermal electrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rios, L. A.; Galvão, R. M. O.; Instituto de Física, Universidade de São Paulo, 05508-900 São Paulo

2013-11-15

In the present work we investigate the existence of obliquely propagating ion-acoustic double layers in magnetized two-electron plasmas. The fluid model is used to describe the ion dynamics, and the hot electron population is modeled via a κ distribution function, which has been proved to be appropriate for modeling non-Maxwellian plasmas. A quasineutral condition is assumed to investigate these nonlinear structures, which leads to the formation of double-layers propagating with slow ion-acoustic velocity. The problem is investigated numerically, and the influence of parameters such as nonthermality is discussed.

Waves in space plasma dipole antenna subsystem

NASA Astrophysics Data System (ADS)

Thomson, Mark

1993-05-01

The Waves In Space Plasma (WISP) flight experiment requires a 50-meter-long deployable dipole antenna subsystem (DASS) to radiate radio frequencies from the STS Orbiter cargo bay. The transmissions are to excite outer ionospheric plasma between the dipole and a free-flying receiver (Spartan) for scientific purposes. This report describes the singular DASS design requirements and how the resulting design satisfies them. A jettison latch is described in some detail. The latch releases the antenna in case of any problems which might prevent the bay doors from closing for re-entry and landing of the Orbiter.

Astrophysical fluid dynamics

NASA Astrophysics Data System (ADS)

Ogilvie, Gordon I.

2016-06-01

> These lecture notes and example problems are based on a course given at the University of Cambridge in Part III of the Mathematical Tripos. Fluid dynamics is involved in a very wide range of astrophysical phenomena, such as the formation and internal dynamics of stars and giant planets, the workings of jets and accretion discs around stars and black holes and the dynamics of the expanding Universe. Effects that can be important in astrophysical fluids include compressibility, self-gravitation and the dynamical influence of the magnetic field that is `frozen in' to a highly conducting plasma. The basic models introduced and applied in this course are Newtonian gas dynamics and magnetohydrodynamics (MHD) for an ideal compressible fluid. The mathematical structure of the governing equations and the associated conservation laws are explored in some detail because of their importance for both analytical and numerical methods of solution, as well as for physical interpretation. Linear and nonlinear waves, including shocks and other discontinuities, are discussed. The spherical blast wave resulting from a supernova, and involving a strong shock, is a classic problem that can be solved analytically. Steady solutions with spherical or axial symmetry reveal the physics of winds and jets from stars and discs. The linearized equations determine the oscillation modes of astrophysical bodies, as well as their stability and their response to tidal forcing.

Hydrodynamic study of plasma amplifiers for soft-x-ray lasers: a transition in hydrodynamic behavior for plasma columns with widths ranging from 20 μm to 2 mm.

PubMed

Oliva, Eduardo; Zeitoun, Philippe; Velarde, Pedro; Fajardo, Marta; Cassou, Kevin; Ros, David; Sebban, Stephan; Portillo, David; le Pape, Sebastien

2010-11-01

Plasma-based seeded soft-x-ray lasers have the potential to generate high energy and highly coherent short pulse beams. Due to their high density, plasmas created by the interaction of an intense laser with a solid target should store the highest amount of energy density among all plasma amplifiers. Our previous numerical work with a two-dimensional (2D) adaptive mesh refinement hydrodynamic code demonstrated that careful tailoring of plasma shapes leads to a dramatic enhancement of both soft-x-ray laser output energy and pumping efficiency. Benchmarking of our 2D hydrodynamic code in previous experiments demonstrated a high level of confidence, allowing us to perform a full study with the aim of the way for 10-100 μJ seeded soft-x-ray lasers. In this paper, we describe in detail the mechanisms that drive the hydrodynamics of plasma columns. We observed transitions between narrow plasmas, where very strong bidimensional flow prevents them from storing energy, to large plasmas that store a high amount of energy. Millimeter-sized plasmas are outstanding amplifiers, but they have the limitation of transverse lasing. In this paper, we provide a preliminary solution to this problem.

BOOK REVIEW: Principles of Plasma Spectroscopy

NASA Astrophysics Data System (ADS)

Osterheld, A. L.

1998-08-01

This book gives a comprehensive treatment of plasma spectroscopy, the quantitative study of line and continuous radiation from high temperature plasmas. This highly interdisciplinary field combines elements of atomic, plasma and statistical physics, and has wide application to simulations and diagnostics of laboratory and astrophysical plasmas. Plasma spectroscopy is naturally intertwined with magnetic and inertial fusion energy science. Radiative processes in plasmas are important in the design of fusion facilities, and can be used to diagnose and control conditions in fusion plasmas. In turn, fusion scientists and facilities have played a central role in developing plasma spectroscopy theory and applications. The book covers radiation from plasmas, spectral line broadening, atomic processes in plasmas and level kinetic models, radiative transfer and applications to spectroscopic plasma diagnostics. It is successful both as an introductory text and as a source book of theoretical and experimental research. The book presents a broad development of the theoretical foundations of these topics, and discusses the seminal papers and critical experiments. There is a strong emphasis on applications of plasma spectroscopy, primarily to plasma diagnostics and calculations of radiative cooling rates. Extensive references (current through the end of 1995) point readers to original material and detailed discussions of advanced topics. Of course, a single text cannot treat all aspects of plasma spectroscopy in depth. The strongest and most detailed section of the book is a long chapter on spectral line broadening. For me, the most significant omission is lack of a discussion of laser assisted transitions which can occur in plasmas produced by high intensity lasers. The book was intentionally written to be accessible to young researchers and graduate students. The level is roughly that of a graduate text. It assumes some familiarity with quantum mechanics and statistical thermodynamics, but develops most of the advanced concepts. Plasma spectroscopy is widely used by non-specialists, and the level and organization of the book are suited to use by researchers developing applications of plasma spectroscopic techniques. Finally, the specialist will profit from the comprehensive overview and excellent bibliography presented. The author is highly qualified to write a general book on the spectroscopy of plasmas. Professor Griem has worked in the field of plasma spectroscopy for more than four decades. He is the author of Plasma Spectroscopy (1964, McGraw-Hill), the first general, quantitative book on the subject of radiation from plasmas, as well as Spectral Line Broadening by Plasmas (1974, Academic Press). Both of these monographs were tremendously influential books. In addition to his long career at the University of Maryland, Professor Griem has worked extensively with numerous research groups in the United States of America and Europe. The depth and breadth of his experience is reflected in the book. The present book is largely new, rather than an update of the 1964 monograph. The two books have a similar organization, especially in the chapters introducing the classical and quantum theories of radiation. The later chapters of the two books diverge strongly as the present text incorporates a vast amount of modern material. The nomenclature and formalism have been updated, and I find this book more accessible than Professor Griem's earlier texts. The other significant changes are that the present book omits the problems at the end of the chapters, many of the tables of numerical results, and the chapters on plasma sources and detectors. While the tables of atomic and line shape results contained in the original book were extremely useful, they have been updated and extended in more recent works. I enthusiastically recommend this book to all scientists interested in the spectroscopy of hot plasmas. Early in his career, Professor Griem wrote the seminal book on plasma spectroscopy. It is gratifying that as a senior scientist he has written a comprehensive monograph incorporating the past three decades of development in the field he so strongly influenced. It is certain to become a coveted and classic book.

Observations of weak ionosphere disturbances on the Kharkov incoherent scatter radar

NASA Astrophysics Data System (ADS)

Cherniak, Iurii; Lysenko, Valery; Cherniak, Iurii

The ionosphere plasma characteristics are responding on variations of solar and magnetic activity, high-power processes in the Earth atmosphere and lithosphere. The research of an ionosphere structure and dynamics is important as for understanding physics of processes and radiophysical problems solution. The method of incoherent scatter (IS) of radiowaves allows determining experimentally as regular variations of electronic concentration Ne and concomitant ionosphere parameters, and their behaviour during natural and antropogeneous origin disturbances. The equipment and measurement technique, developed by authors, are allows obtaining reliable data about an ionosphere behaviour during various origin and intensity perturbations. Oservations results of main parameters IS signal and ionosphere plasma during weak magnetic storm, solar eclipse, ionosphere disturbances caused by start of the high-power rocket are presented. Experimentally obtained on the Kharkov IS radar altitude-temporary dependences of disturbed ionosphere plasma parameters during weak intensity magnetic storm 04-06 April 2006 (Kp = 5, Dst = -100 nTl) were adduced. During a main storm phase the positive perturbation was observed (Ne is increased in 1.3 times), April 5, at maximum Dst - negative perturbation (Ne is decreased in 1.6 times), April 6 - positive perturbation (the second positive storm phase - Ne was increased at 1.33 times). During negative ionosphere storm the height of a F2 layer maximum was increased on 30-40 km, ionic temperature in the day is increased on 150K, electronic temperature is increased on 600K. For date 29.03.2006, when take place partial Sun eclipse (disk shadow factor 73 During launch heavy class rocket "Proton-K" december 25, 2006 from Baikonur cosmodrome (distance up to a view point of 2500 km) the perturbations in close space were observed. By measurements results of ionosphere plasma cross-section two disturbed areas were registered. First was observed through 8 mines, and second - through 60 mines after start of the rocket. The altitude-temporary diagrams of ionosphere plasma cross-section distribution were adduced.

Space Plasma Shown to Make Satellite Solar Arrays Fail

NASA Technical Reports Server (NTRS)

Ferguson, Dale C.

1999-01-01

In 1997, scientists and engineers of the Photovoltaic and Space Environments Branch of the NASA Lewis Research Center, Maxwell Technologies, and Space Systems/Loral discovered a new failure mechanism for solar arrays on communications satellites in orbit. Sustained electrical arcs, initiated by the space plasma and powered by the solar arrays themselves, were found to have destroyed solar array substrates on some Space Systems/Loral satellites, leading to array failure. The mechanism was tested at Lewis, and mitigation strategies were developed to prevent such disastrous occurrences on-orbit in the future. Deep Space 1 is a solar-electric-powered space mission to a comet, launched on October 24, 1998. Early in 1998, scientists at Lewis and Ballistic Missile Defense Organization (BMDO) realized that some aspects of the Deep Space 1 solar arrays were nearly identical to those that had led to the failure of solar arrays on Space Systems/Loral satellites. They decided to modify the Deep Space 1 arrays to prevent catastrophic failure in space. The arrays were suitably modified and are now performing optimally in outer space. Finally, the Earth Observing System (EOS) AM1, scheduled for launch in mid-1999, is a NASA mission managed by the Goddard Space Flight Center. Realizing the importance of Lewis testing on the Loral arrays, EOS-AM1 management asked Lewis scientists to test their solar arrays to show that they would not fail in the same way. The first phase of plasma testing showed that sustained arcing would occur on the unmodified EOS-AM1 arrays, so the arrays were removed from the spacecraft and fixed. Now, Lewis scientists have finished plasma testing of the modified array configuration to ensure that EOS-AM1 will have no sustained arcing problems on-orbit.

Comparison of reconnection in magnetosphere and solar corona

NASA Astrophysics Data System (ADS)

Imada, Shinsuke; Hirai, Mariko; Isobe, Hiroaki; Oka, Mitsuo; Watanabe, Kyoko; Minoshima, Takashi

One of the most famous rapid energy conversion mechanisms in space is a magnetic reconnec-tion. The general concept of a magnetic reconnection is that the rapid energy conversion from magnetic field energy to thermal energy, kinetic energy or non-thermal particle energy. The understanding of rapid energy conversion rates from magnetic field energy to other energy is the fundamental and essential problem in the space physics. One of the important goals for studying magnetic reconnection is to answer what plasma condition/parameter controls the energy conversion rates. Earth's magnetotail has been paid much attention to discuss a mag-netic reconnection, because we can discuss magnetic reconnection characteristics in detail with direct in-situ observation. Recently, solar atmosphere has been focused as a space laboratory for magnetic reconnection because of its variety in plasma condition. So far considerable effort has been devoted toward understanding the energy conversion rates of magnetic reconnection, and various typical features associated with magnetic reconnection have been observed in the Earth's magnetotail and the solar corona. In this talk, we first introduce the variety of plasma condition/parameter in solar corona and Earth's magnetotail. Later, we discuss what plasma condition/parameter controls the energy conversion from magnetic field to especially non-thermal particle. To compare non-thermal electron and ion acceleration in magnetic reconnection, we used Hard X-ray (electron) /Neu-tron monitor (ion) for solar corona and Geotail in-situ measurement (electron and ion) for magnetoatil. We found both of electron and ion accelerations are roughly controlled by re-connection electric field (reconnection rate). However, some detail points are different in ion and electron acceleration. Further, we will discuss what is the major difference between solar corona and Earth's magnetotail for particle acceleration.

Polysilicon planarization and plug recess etching in a decoupled plasma source chamber using two endpoint techniques

NASA Astrophysics Data System (ADS)

Kaplita, George A.; Schmitz, Stefan; Ranade, Rajiv; Mathad, Gangadhara S.

1999-09-01

The planarization and recessing of polysilicon to form a plug are processes of increasing importance in silicon IC fabrication. While this technology has been developed and applied to DRAM technology using Trench Storage Capacitors, the need for such processes in other IC applications (i.e. polysilicon studs) has increased. Both planarization and recess processes usually have stringent requirements on etch rate, recess uniformity, and selectivity to underlying films. Additionally, both processes generally must be isotropic, yet must not expand any seams that might be present in the polysilicon fill. These processes should also be insensitive to changes in exposed silicon area (pattern factor) on the wafer. A SF6 plasma process in a polysilicon DPS (Decoupled Plasma Source) reactor has demonstrated the capability of achieving the above process requirements for both planarization and recess etch. The SF6 process in the decoupled plasma source reactor exhibited less sensitivity to pattern factor than in other types of reactors. Control of these planarization and recess processes requires two endpoint systems to work sequentially in the same recipe: one for monitoring the endpoint when blanket polysilicon (100% Si loading) is being planarized and one for monitoring the recess depth while the plug is being recessed (less than 10% Si loading). The planarization process employs an optical emission endpoint system (OES). An interferometric endpoint system (IEP), capable of monitoring lateral interference, is used for determining the recess depth. The ability of using either or both systems is required to make these plug processes manufacturable. Measuring the recess depth resulting from the recess process can be difficult, costly and time- consuming. An Atomic Force Microscope (AFM) can greatly alleviate these problems and can serve as a critical tool in the development of recess processes.

Spontaneous abortion is associated with elevated systemic C5a and reduced mRNA of complement inhibitory proteins in placenta

PubMed Central

Banadakoppa, M; Chauhan, M S; Havemann, D; Balakrishnan, M; Dominic, J S; Yallampalli, C

2014-01-01

Spontaneous abortion in early pregnancy due to unknown reasons is a common problem. The excess complement activation and consequent placental inflammation and anti-angiogenic milieu is emerging as an important associated factor in many pregnancy-related complications. In the present study we sought to examine the expression of complement inhibitory proteins at the feto–maternal interface and levels of complement split products in the circulation to understand their role in spontaneous abortion. Consenting pregnant women who either underwent elective abortion due to non-clinical reasons (n = 13) or suffered miscarriage (n = 14) were recruited for the study. Systemic levels of complement factors C3a and C5a were measured by enzyme-linked immunosorbent assay (ELISA). Plasma C5 and C3 protein levels were examined by Western blot. Expressions of complement regulatory proteins such as CD46 and CD55 in the decidua were investigated by quantitative polymerase chain reaction (PCR) and Western blot. The median of plasma C3a level was 82·83 ng/ml and 66·17 ng/ml in elective and spontaneous abortion patients, respectively. Medians of plasma C5a levels in elective and spontaneous abortion patients were 0·96 ng/ml and 1·14 ng/ml, respectively. Only plasma C5a levels but not C3a levels showed significant elevation in spontaneous abortion patients compared to elective abortion patients. Further, there was a threefold decrease in the mRNA expressions of complement inhibitory proteins CD46 and CD55 in the decidua obtained from spontaneous abortion patients compared to that of elective abortion patients. These data suggested that dysregulated complement cascade may be associated with spontaneous abortion. PMID:24802103

Quasineutral plasma expansion into infinite vacuum as a model for parallel ELM transport

NASA Astrophysics Data System (ADS)

Moulton, D.; Ghendrih, Ph; Fundamenski, W.; Manfredi, G.; Tskhakaya, D.

2013-08-01

An analytic solution for the expansion of a plasma into vacuum is assessed for its relevance to the parallel transport of edge localized mode (ELM) filaments along field lines. This solution solves the 1D1V Vlasov-Poisson equations for the adiabatic (instantaneous source), collisionless expansion of a Gaussian plasma bunch into an infinite space in the quasineutral limit. The quasineutral assumption is found to hold as long as λD0/σ0 ≲ 0.01 (where λD0 is the initial Debye length at peak density and σ0 is the parallel length of the Gaussian filament), a condition that is physically realistic. The inclusion of a boundary at x = L and consequent formation of a target sheath is found to have a negligible effect when L/σ0 ≳ 5, a condition that is physically plausible. Under the same condition, the target flux densities predicted by the analytic solution are well approximated by the ‘free-streaming’ equations used in previous experimental studies, strengthening the notion that these simple equations are physically reasonable. Importantly, the analytic solution predicts a zero heat flux density so that a fluid approach to the problem can be used equally well, at least when the source is instantaneous. It is found that, even for JET-like pedestal parameters, collisions can affect the expansion dynamics via electron temperature isotropization, although this is probably a secondary effect. Finally, the effect of a finite duration, τsrc, for the plasma source is investigated. As is found for an instantaneous source, when L/σ0 ≳ 5 the presence of a target sheath has a negligible effect, at least up to the explored range of τsrc = L/cs (where cs is the sound speed at the initial temperature).

Use of Atmospheric-Pressure Plasma Jet for Polymer Surface Modification: An Overview

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuettner, Lindsey A.

Atmospheric-pressure plasma jets (APPJs) are playing an increasingly important role in materials processing procedures. Plasma treatment is a useful tool to modify surface properties of materials, especially polymers. Plasma reacts with polymer surfaces in numerous ways thus the type of process gas and plasma conditions must be explored for chosen substrates and materials to maximize desired properties. This report discusses plasma treatments and looks further into atmospheric-pressure plasma jets and the effects of gases and plasma conditions. Following the short literature review, a general overview of the future work and research at Los Alamos National Laboratory (LANL) is discussed.

Plasma medicine—current state of research and medical application

NASA Astrophysics Data System (ADS)

Weltmann, K.-D.; von Woedtke, Th

2017-01-01

Plasma medicine means the direct application of cold atmospheric plasma (CAP) on or in the human body for therapeutic purposes. Further, the field interacts strongly with results gained for biological decontamination. Experimental research as well as first practical application is realized using two basic principles of CAP sources: dielectric barrier discharges (DBD) and atmospheric pressure plasma jets (APPJ). Originating from the fundamental insights that the biological effects of CAP are most probably caused by changes of the liquid environment of cells, and are dominated by reactive oxygen and nitrogen species (ROS, RNS), basic mechanisms of biological plasma activity are identified. It was demonstrated that there is no increased risk of cold plasma application and, above all, there are no indications for genotoxic effects. The most important biological effects of cold atmospheric pressure plasma were identified: (1) inactivation of a broad spectrum of microorganisms including multidrug resistant ones; (2) stimulation of cell proliferation and tissue regeneration with lower plasma treatment intensity (treatment time); (3) inactivation of cells by initialization of programmed cell death (apoptosis) with higher plasma treatment intensity (treatment time). In recent years, the main focus of clinical applications was in the field of wound healing and treatment of infective skin diseases. First CAP sources are CE-certified as medical devices now which is the main precondition to start the introduction of plasma medicine into clinical reality. Plasma application in dentistry and, above all, CAP use for cancer treatment are becoming more and more important research fields in plasma medicine. A further in-depth knowledge of control and adaptation of plasma parameters and plasma geometries is needed to obtain suitable and reliable plasma sources for the different therapeutic indications and to open up new fields of medical application.

Motivational differences between whole blood and plasma donors already exist before their first donation experience.

PubMed

Veldhuizen, Ingrid; van Dongen, Anne

2013-08-01

The demand for plasma products has increased rapidly. It is therefore important to understand donating behavior by plasma donors. This study investigates whether motivational differences between whole blood and plasma donors already exist at the beginning of a donor career. New donors (n = 4861) were invited to fill out a questionnaire before their first donation (response, 61%). The questionnaire assessed variables from the Theory of Planned Behavior (intention, self-efficacy, attitude, and norms), conscientiousness, and donation anxiety. Three years later it was determined who became whole blood or plasma donor. Multivariable linear regression analyses for intention were fitted separately for whole blood and plasma donors. A logistic regression analysis was executed to estimate the effect of intention at the beginning of a donor career on becoming a plasma donor. Plasma donors had a higher intention, self-efficacy, attitude, and conscientiousness and a lower anxiety than whole blood donors. In plasma and whole blood donors, both self-efficacy and cognitive attitude were positively related to intention but with different strength (plasma, β = 0.47 and β = 0.30; whole blood, β = 0.57 and β = 0.17). Having a high level of intention increased the odds of becoming a plasma donor (odds ratio, 1.33; 95% confidence interval, 1.12-1.59). Motivational differences already exist between future whole blood and plasma donors before their first donation. Although a feeling of self-efficacy is necessary for all new donors, more favorable cognitions are important for future plasma donors. Recruitment strategies for plasma donors should focus on attracting the more self-confident donors by highlighting the usefulness of plasma donation. © 2012 American Association of Blood Banks.

Plasma Discharge Process in a Pulsed Diaphragm Discharge System

NASA Astrophysics Data System (ADS)

Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

2014-12-01

As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

LC-QTOF-MS-based targeted metabolomics of arginine-creatine metabolic pathway-related compounds in plasma: application to identify potential biomarkers in pediatric chronic kidney disease.

PubMed

Benito, Sandra; Sánchez, Alicia; Unceta, Nora; Andrade, Fernando; Aldámiz-Echevarria, Luis; Goicolea, M Aránzazu; Barrio, Ramón J

2016-01-01

Chronic kidney disease (CKD) is a major epidemiologic problem which causes several disturbances in adults and in pediatrics. Despite being a worldwide public health problem, information available for CKD in the pediatric population is scarce. For that reason, an ion-pair reversed-phase liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) method has been developed and validated in order to analyze 16 amino acids, amino acid derivatives, and analogous compounds related to the arginine-creatine metabolic pathway that are suspicious of being increased or decreased in plasma from patients with CKD. The analytical method involved the addition of dithiothreitol, a reducing agent which reduces disulfide and thus giving total aminothiol concentration, as well as a simple precipitation of plasma proteins. Moreover, despite amino acids being usually derivatized to improve their retention time and to enhance their signal, for this method, an ion-pairing reagent was used, thus avoiding the need for derivatization. Subsequently, analysis of plasma from pediatric patients suffering from CKD and control pediatrics was carried out. As a result, glycine, citrulline, creatinine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) were significantly increased in patients with CKD, regardless of their creatinine level, whereas in addition to these compounds dimethylglycine was also increased when CKD patients had plasma creatinine concentrations above 12 μg mL(-1), thus all are suggested as potential biomarkers for renal impairment.

Development of hybrid computer plasma models for different pressure regimes

NASA Astrophysics Data System (ADS)

Hromadka, Jakub; Ibehej, Tomas; Hrach, Rudolf

2016-09-01

With increased performance of contemporary computers during last decades numerical simulations became a very powerful tool applicable also in plasma physics research. Plasma is generally an ensemble of mutually interacting particles that is out of the thermodynamic equilibrium and for this reason fluid computer plasma models give results with only limited accuracy. On the other hand, much more precise particle models are often limited only on 2D problems because of their huge demands on the computer resources. Our contribution is devoted to hybrid modelling techniques that combine advantages of both modelling techniques mentioned above, particularly to their so-called iterative version. The study is focused on mutual relations between fluid and particle models that are demonstrated on the calculations of sheath structures of low temperature argon plasma near a cylindrical Langmuir probe for medium and higher pressures. Results of a simple iterative hybrid plasma computer model are also given. The authors acknowledge the support of the Grant Agency of Charles University in Prague (project 220215).

High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena

NASA Astrophysics Data System (ADS)

Li, Zhaorui; Livescu, Daniel

2017-11-01

The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

Interaction of UV laser pulses with reactive dusty plasmas

NASA Astrophysics Data System (ADS)

van de Wetering, Ferdi; Beckers, Job; Nijdam, Sander; Oosterbeek, Wouter; Kovacevic, Eva; Berndt, Johannes

2016-09-01

This contribution deals with the effects of UV photons on the synthesis and transport of nanoparticles in reactive complex plasmas (capacitively coupled RF discharge). First measurements showed that the irradiation of a reactive acetylene-argon plasma with high-energy, ns UV laser pulses (355 nm, 75 mJ pulse energy, repetition frequency 10Hz) can have a large effect on the global discharge characteristics. One particular example concerns the formation of a dust void in the center of the discharge. At sufficiently high pulse energies, this formation of a dust free region - which occurs without laser irradiation-is totally suppressed. Moreover the experiments indicate that the laser pulses influence the early stages of the particle formation. Although the interaction between the laser and the plasma is not yet fully understood, it is remarkable that these localized nanosecond laser pulses can influence the plasma on a global scale. Besides new insights into fundamental problems, this phenomenon opens also new possibilities for the controlled manipulation of particle growth and particle transport in reactive plasmas.

Physical interpretation of Jeans instability in quantum plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akbari-Moghanjoughi, M.; International Centre for Advanced Studies in Physical Sciences and Institute for Theoretical Physics, Ruhr University Bochum, D-44780 Bochum

2014-08-15

In this paper, we use the quantum hydrodynamics and its hydrostatic limit to investigate the newly posed problem of Jeans instability in quantum plasmas from a different point of view in connection with the well-known Chandrasekhar mass-limit on highly collapsed degenerate stellar configurations. It is shown that the hydrodynamic stability of a spherically symmetric uniform quantum plasma with a given fixed mass is achieved by increase in its mass-density or decrease in the radius under the action of gravity. It is also remarked that for masses beyond the limiting Jeans-mass, the plasma becomes completely unstable and the gravitational collapse wouldmore » proceed forever. This limiting mass is found to depend strongly on the composition of the quantum plasma and the atomic-number of the constituent ions, where it is observed that heavier elements rather destabilize the quantum plasma hydrodynamically. It is also shown that the Chandrasekhar mass-limit for white dwarf stars can be directly obtained from the hydrostatic limit of our model.« less

A macroscopic plasma Lagrangian and its application to wave interactions and resonances

NASA Technical Reports Server (NTRS)

Peng, Y. K. M.

1974-01-01

The derivation of a macroscopic plasma Lagrangian is considered, along with its application to the description of nonlinear three-wave interaction in a homogeneous plasma and linear resonance oscillations in a inhomogeneous plasma. One approach to obtain the Lagrangian is via the inverse problem of the calculus of variations for arbitrary first and second order quasilinear partial differential systems. Necessary and sufficient conditions for the given equations to be Euler-Lagrange equations of a Lagrangian are obtained. These conditions are then used to determine the transformations that convert some classes of non-Euler-Lagrange equations to Euler-Lagrange equation form. The Lagrangians for a linear resistive transmission line and a linear warm collisional plasma are derived as examples. Using energy considerations, the correct macroscopic plasma Lagrangian is shown to differ from the velocity-integrated low Lagrangian by a macroscopic potential energy that equals twice the particle thermal kinetic energy plus the energy lost by heat conduction.

Computational study of nonlinear plasma waves. [plasma simulation model applied to electrostatic waves in collisionless plasma

NASA Technical Reports Server (NTRS)

Matsuda, Y.

1974-01-01

A low-noise plasma simulation model is developed and applied to a series of linear and nonlinear problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. It is demonstrated that use of the hybrid simulation model allows economical studies to be carried out in both the linear and nonlinear regimes with better quantitative results, for comparable computing time, than can be obtained by conventional particle simulation models, or direct solution of the Vlasov equation. The characteristics of the hybrid simulation model itself are first investigated, and it is shown to be capable of verifying the theoretical linear dispersion relation at wave energy levels as low as .000001 of the plasma thermal energy. Having established the validity of the hybrid simulation model, it is then used to study the nonlinear dynamics of monochromatic wave, sideband instability due to trapped particles, and satellite growth.

Plasma rotation by electric and magnetic fields in a discharge cylinder

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.; Hong, S. H.

1977-01-01

A theoretical model for an electric discharge consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field is developed to study the rotation of the discharge plasma in the crossed electric and magnetic fields. The associated boundary-value problem for the coupled partial differential equations which describe the electric potential and the plasma velocity fields is solved in closed form. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number and the Hall coefficient. As a result of Lorentz forces, the plasma rotates with speeds as high as 1 million cm/sec around its axis of symmetry at typical conditions. As an application, it is noted that rotating discharges of this type could be used to develop a high-density plasma-ultracentrifuge driven by j x B forces, in which the lighter (heavier) ion and atom components would be enriched in (off) the center of the discharge cylinder.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakharov, Leonic E.; Li, Xujing

This paper formulates the Tokamak Magneto-Hydrodynamics (TMHD), initially outlined by X. Li and L.E. Zakharov [Plasma Science and Technology, accepted, ID:2013-257 (2013)] for proper simulations of macroscopic plasma dynamics. The simplest set of magneto-hydrodynamics equations, sufficient for disruption modeling and extendable to more refined physics, is explained in detail. First, the TMHD introduces to 3-D simulations the Reference Magnetic Coordinates (RMC), which are aligned with the magnetic field in the best possible way. The numerical implementation of RMC is adaptive grids. Being consistent with the high anisotropy of the tokamak plasma, RMC allow simulations at realistic, very high plasma electricmore » conductivity. Second, the TMHD splits the equation of motion into an equilibrium equation and the plasma advancing equation. This resolves the 4 decade old problem of Courant limitations of the time step in existing, plasma inertia driven numerical codes. The splitting allows disruption simulations on a relatively slow time scale in comparison with the fast time of ideal MHD instabilities. A new, efficient numerical scheme is proposed for TMHD.« less

Molecular Diagnostics of Fusion and Laboratory Plasmas

NASA Astrophysics Data System (ADS)

Fantz, U.

2005-05-01

The presence of molecules in the cold scrape-off layer of fusion experiments and industrial plasmas requires an understanding of the molecular dynamics in these low temperature plasmas. Suitable diagnostic methods can provide an insight in molecular processes in the plasma volume as well as for plasma surface interactions. A very simple but powerful technique is the molecular emission spectroscopy. Spectra are obtained easily, whereas interpretation might be very complex and relies on the availability of atomic and molecular data. Examples are given for hydrogen plasmas and plasmas with hydrocarbons which both are of importance in industrial applications as well as in fusion experiments.

Problems Associated with Attaching Strain Gages to Titanium Alloy Ti-61-4V

NASA Technical Reports Server (NTRS)

Jenkins, J. M.; Lemcoe, M. M.

1977-01-01

Weldable strain gages have shown excellent high temperature characteristics for supersonic cruise aircraft application. The spotwelding attachment method, however, has resulted in serious reductions in the fatigue life of titanium alloy (Ti-6Al-4V) fatigue specimens. The reduction is so severe that the use of weldable strain gages on operational aircraft must be prohibited. The cause of the fatigue problem is thought to be a combination of the microstructure changes in the material caused by spotwelding and the presence of the flange of the stain gage. Brazing, plating, and plasma spraying were investigated as substitutes for spotwelding. The attachment of a flangeless gage by plasma spraying provided the most improvement in the fatigue life of the titanium.

Considerations in As analysis and speciation

USGS Publications Warehouse

Edwards, M.; Patel, S.; McNeil, L.; Chen, H.W.; Frey, M.; Eaton, A.D.; Antweiler, Ronald C.; Taylor, Howard E.

1998-01-01

This article summarizes recent experiences in arsenic (As) quantification, preservation, and speciation developed during AWWA Research Foundation (AWWARF) and Water Industry Technical Action Fund (WITAF) projects. The goal of this article is to alert analysts and decision-makers to potential problems in As analysis and speciation, because there appear to be several unresolved problems with routine analytical approaches. In true split drinking water samples As was quantified by three accepted analytical methods in three laboratories. The techniques used were graphite furnace atomic absorption spectrometry (GFAAS), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation inductively coupled plasma-emission spectrometry (HG-ICP-AES). Experimental findings are organized into sections on As analysis, particulate As in water supplies, and examination of As speciation methods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duarte, V. N.; Clemente, R. A.

The steady one-dimensional planar plasma sheath problem, originally considered by Tonks and Langmuir, is revisited. Assuming continuously generated free-falling ions and isothermal electrons and taking into account electron inertia, it is possible to describe the problem in terms of three coupled integro-differential equations that can be numerically integrated. The inclusion of electron inertia in the model allows us to obtain the value of the plasma floating potential as resulting from an electron density discontinuity at the walls, where the electrons attain sound velocity and the electric potential is continuous. Results from numerical computation are presented in terms of plots formore » densities, electric potential, and particles velocities. Comparison with results from literature, corresponding to electron Maxwell-Boltzmann distribution (neglecting electron inertia), is also shown.« less

A tutorial introduction to the statistical theory of turbulent plasmas, a half-century after Kadomtsev’s Plasma Turbulence and the resonance-broadening theory of Dupree and Weinstock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krommes, John A.

In honour of the 50th anniversary of the influential review/monograph on plasma turbulence by B. B. Kadomtsev as well as the seminal works of T. H. Dupree and J. Weinstock on resonance-broadening theory, an introductory tutorial is given about some highlights of the statistical–dynamical description of turbulent plasmas and fluids, including the ideas of nonlinear incoherent noise, coherent damping, and self-consistent dielectric response. The statistical closure problem is introduced. Incoherent noise and coherent damping are illustrated with a solvable model of passive advection. Self-consistency introduces turbulent polarization effects that are described by the dielectric functionmore » $${\\mathcal{D}}$$. Dupree’s method of using$${\\mathcal{D}}$$to estimate the saturation level of turbulence is described; then it is explained why a more complete theory that includes nonlinear noise is required. The general theory is best formulated in terms of Dyson equations for the covariance$C$$and an infinitesimal response function$$R$$, which subsumes$${\\mathcal{D}}$$. An important example is the direct-interaction approximation (DIA). It is shown how to use Novikov’s theorem to develop an$$\\boldsymbol{x}$$-space approach to the DIA that is complementary to the original$$\\boldsymbol{k}$$-space approach of Kraichnan. A dielectric function is defined for arbitrary quadratically nonlinear systems, including the Navier–Stokes equation, and an algorithm for determining the form of$${\\mathcal{D}}$$in the DIA is sketched. The independent insights of Kadomtsev and Kraichnan about the problem of the DIA with random Galilean invariance are described. The mixing-length formula for drift-wave saturation is discussed in the context of closures that include nonlinear noise (shielded by$${\\mathcal{D}}$$). The role of$$R$in the calculation of the symmetry-breaking (zonostrophic) instability of homogeneous turbulence to the generation of inhomogeneous mean flows is addressed. The second-order cumulant expansion and the stochastic structural stability theory are also discussed in that context. In conclusion, various historical research threads are mentioned and representative entry points to the literature are given. In addition, some outstanding conceptual issues are enumerated.« less

A tutorial introduction to the statistical theory of turbulent plasmas, a half-century after Kadomtsev’s Plasma Turbulence and the resonance-broadening theory of Dupree and Weinstock

DOE PAGES

Krommes, John A.

2015-09-21

In honour of the 50th anniversary of the influential review/monograph on plasma turbulence by B. B. Kadomtsev as well as the seminal works of T. H. Dupree and J. Weinstock on resonance-broadening theory, an introductory tutorial is given about some highlights of the statistical–dynamical description of turbulent plasmas and fluids, including the ideas of nonlinear incoherent noise, coherent damping, and self-consistent dielectric response. The statistical closure problem is introduced. Incoherent noise and coherent damping are illustrated with a solvable model of passive advection. Self-consistency introduces turbulent polarization effects that are described by the dielectric functionmore » $${\\mathcal{D}}$$. Dupree’s method of using$${\\mathcal{D}}$$to estimate the saturation level of turbulence is described; then it is explained why a more complete theory that includes nonlinear noise is required. The general theory is best formulated in terms of Dyson equations for the covariance$C$$and an infinitesimal response function$$R$$, which subsumes$${\\mathcal{D}}$$. An important example is the direct-interaction approximation (DIA). It is shown how to use Novikov’s theorem to develop an$$\\boldsymbol{x}$$-space approach to the DIA that is complementary to the original$$\\boldsymbol{k}$$-space approach of Kraichnan. A dielectric function is defined for arbitrary quadratically nonlinear systems, including the Navier–Stokes equation, and an algorithm for determining the form of$${\\mathcal{D}}$$in the DIA is sketched. The independent insights of Kadomtsev and Kraichnan about the problem of the DIA with random Galilean invariance are described. The mixing-length formula for drift-wave saturation is discussed in the context of closures that include nonlinear noise (shielded by$${\\mathcal{D}}$$). The role of$$R$in the calculation of the symmetry-breaking (zonostrophic) instability of homogeneous turbulence to the generation of inhomogeneous mean flows is addressed. The second-order cumulant expansion and the stochastic structural stability theory are also discussed in that context. In conclusion, various historical research threads are mentioned and representative entry points to the literature are given. In addition, some outstanding conceptual issues are enumerated.« less

A geometric theory of waves and its applications to plasma physics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruiz, Daniel

Waves play an essential role in many aspects of plasma dynamics. For example, they are indispensable in plasma manipulation and diagnostics. Although the physics of waves is well understood in the context of relatively simple problems, difficulties arise when studying waves that propagate in inhomogeneous or nonlinear media. This thesis presents a new systematic wave theory based on phase-space variational principles. In this dissertation, waves are treated as geometric objects of a variational theory rather than formal solutions of specific PDEs. This approach simplifies calculations, highlights the underlying wave symmetries, and leads to improved modeling of wave dynamics. Specifically, thismore » dissertation presents two important breakthroughs that were obtained in the general theory of waves. The first main contribution of the present dissertation is an extension of the theory of geometrical optics (GO) in order to include polarization effects. Even when diffraction is ignored, the GO ray equations are not entirely accurate. This occurs because GO treats wave rays as classical particles described by their position and momentum coordinates. However, vector waves have another degree of freedom, their polarization. As a result, wave rays can behave as particles with spin and show polarization dynamics, such as polarization precession and polarization-driven bending of ray trajectories. In this thesis, the theory of GO is reformulated as a first-principle Lagrangian wave theory that governs both mentioned polarization phenomena simultaneously. The theory was applied successfully to several systems of interest, such as relativistic spin-$1/2$ particles and radio-frequency waves propagating in magnetized plasmas. The second main contribution of this thesis is the development of a phase-space method to study basic properties of nonlinear wave--wave interactions. Specifically, a general theory is proposed that describes the ponderomotive refraction that a wave can experience when interacting with another wave. It is also shown that phase-space methods can be useful to study problems in the field of wave turbulence, such as the nonlinear interaction of high-frequency waves with large-scale structures. Overall, the results obtained can serve as a basis for future studies on more complex nonlinear wave--wave interactions, such as modulational instabilities in general wave ensembles or wave turbulence.« less

High energy from space

NASA Technical Reports Server (NTRS)

Margon, Bruce; Canizares, Claude; Catura, Richard C.; Clark, George W.; Fichtel, Carl E.; Friedman, Herbert; Giacconi, Riccardo; Grindlay, Jonathan E.; Helfand, David J.; Holt, Stephen S.

1991-01-01

The following subject areas are covered: (1) important scientific problems for high energy astrophysics (stellar activity, the interstellar medium in galaxies, supernovae and endpoints of stellar evolution, nucleosynthesis, relativistic plasmas and matter under extreme conditions, nature of gamma-bursts, identification of black holes, active nuclei, accretion physics, large-scale structures, intracluster medium, nature of dark matter, and the X- and gamma-ray background); (2) the existing experimental programs (Advanced X-Ray Astrophysics Facility (AXAF), Gamma Ray Observatory (GRO), X-Ray Timing Explorer (XTE), High Energy Transient Experiment (HETE), U.S. participation in foreign missions, and attached Shuttle and Space Station Freedom payloads); (3) major missions for the 1990's; (4) a new program of moderate missions; (5) new opportunities for small missions; (6) technology development issues; and (7) policy issues.

Measurements of the properties of solar wind plasma relevant to studies of its coronal sources

NASA Technical Reports Server (NTRS)

Neugebauer, M.

1982-01-01

Interplanetary measurements of the speeds, densities, abundances, and charge states of solar wind ions are diagnostic of conditions in the source region of the solar wind. The absolute values of the mass, momentum, and energy fluxes in the solar wind are not known to an accuracy of 20%. The principal limitations on the absolute accuracies of observations of solar wind protons and alpha particles arise from uncertain instrument calibrations, from the methods used to reduce the data, and from sampling biases. Sampling biases are very important in studies of alpha particles. Instrumental resolution and measurement ambiguities are additional major problems for the observation of ions heavier than helium. Progress in overcoming some of these measurement inadequacies is reviewed.

Design of a submillimeter laser Thomson scattering system for measurement of ion temperature in SUMMA

NASA Technical Reports Server (NTRS)

Praddaude, H. C.; Woskoboinikow, P.

1978-01-01

A thorough discussion of submillimeter laser Thomson scattering for the measurement of ion temperature in plasmas is presented. This technique is very promising and work is being actively pursued on the high power lasers and receivers necessary for its implementation. In this report we perform an overall system analysis of the Thomson scattering technique aimed to: (1) identify problem areas; (2) establish specifications for the main components of the apparatus; (3) study signal processing alternatives and identify the optimum signal handling procedure. Because of its importance for the successful implementation of this technique, we also review the work presently being carried out on the optically pumped submillimeter CH3F and D2O lasers.

[Classification of results of studying blood plasma with laser correlation spectroscopy based on semiotics of preclinical and clinical states].

PubMed

Ternovoĭ, K S; Kryzhanovskiĭ, G N; Musiĭchuk, Iu I; Noskin, L A; Klopov, N V; Noskin, V A; Starodub, N F

1998-01-01

The usage of laser correlation spectroscopy for verification of preclinical and clinical states is substantiated. Developed "semiotic" classifier for solving the problems of preclinical and clinical states is presented. The substantiation of biological algorithms as well as the mathematical support and software for the proposed classifier for the data of laser correlation spectroscopy of blood plasma are presented.

Waves and instabilities in plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, L.

1987-01-01

The contents of this book are: Plasma as a Dielectric Medium; Nyquist Technique; Absolute and Convective Instabilities; Landau Damping and Phase Mixing; Particle Trapping and Breakdown of Linear Theory; Solution of Viasov Equation via Guilding-Center Transformation; Kinetic Theory of Magnetohydrodynamic Waves; Geometric Optics; Wave-Kinetic Equation; Cutoff and Resonance; Resonant Absorption; Mode Conversion; Gyrokinetic Equation; Drift Waves; Quasi-Linear Theory; Ponderomotive Force; Parametric Instabilities; Problem Sets for Homework, Midterm and Final Examinations.

Millimeter wave generation by relativistic electron beams

NASA Astrophysics Data System (ADS)

Kuo, S. S.; Cheo, B. R.; Tiong, K. K.; Whang, M. H.

1985-11-01

The classical technique of transformation and characteristics is employed to analyze the problem of strong turbulence in unmagnetized plasmas. The effects of resonance broadening and perturbation expansion are treated simultaneously without time securities. The renormalization procedure is used in the transformed Vlasov equation to analyze the turbulence and to derive explicitly a diffusion equation. Analyses are extended to imhomogeneous plasma and the relationship between the transformation and ponderomotive force is obtained.

Physics of spinning gases and plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geyko, Vasily I.

Initially motivated by the problem of compression of spinning plasma in Z-pinch devices and related applications, the thesis explores a number of interesting smaller-scale problems related to physics of gas and plasma rotation. In particular, thermodynamics of ideal spinning gas is studied. It is found that rotation modifies the heat capacity of the gas and reduces the gas compressibility. It is also proposed that, by performing a series of measurement of external parameters of a spinning gas, one can infer the distribution of masses of gas constituents. It is also proposed how to use the rotation-dependent heat capacity for improvingmore » the thermodynamic efficiency of internal combustion engines. To that end, two possible engine embodiments are proposed and explored in detail. In addition, a transient piezothermal effect is discovered numerically and is given a theoretical explanation. The effect consists of the formation of a radial temperature gradient driven by gas heating or compression along the rotation axis. By elaborating on this idea, a theoretical explanation is proposed also for the operation of so-called vortex tubes, which so far have been lacking rigorous theory. Finally, adiabatic compression of spinning plasmas and ionized gases are considered, and the effect of the electrostatic interactions on the compressibility and heat capacity is predicted.« less

Photoplasma of optically excited metal vapors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezuglov, N.N.; Llyucharev, A.N.; Stacewicz, T.

1994-09-01

A wide range of questions associated with various aspects of photoplasma physics is considered. A comprehensive analysis of processes of optical excitation and de-excitation depending on optical characteristics of an absorbing gas medium is given. Analytical methods used for determining the excitation degree of photoresonance plasma in conditions of resonance radiation transfer are described. The accuracy of the Biberman approximation for effective lifetimes in population kinetics of resonance plasma states is analyzed for many experimental conditions. A detailed discussion of primary ionization mechanisms in photoplasma is given; the kinetics of ionization processes is discussed; and systematization of various types ofmore » photoresonance plasma is presented. Basis aspects of the LIBORS model, which is widely used for studying ionization kinetics of laser photoresonance plasma, and its limitations are considered. An ingenious method used to analytically solve a class of decay-type nonlinear problems, which arise for the capture equation in the case of noticeable saturation of a resonance transition by a short laser pulse, is described. A reliable quantitative description of fluorescence decay curve peculiarities that are associated with the bleaching of gases at resonance line frequencies can be obtained by this method. Some possible applications of photoplasma in problems of optics and spectroscopy are considered. 75 refs., 24 figs., 1 tab.« less

Concept for a beryllium divertor with in-situ plasma spray surface regeneration

NASA Astrophysics Data System (ADS)

Smith, M. F.; Watson, R. D.; McGrath, R. T.; Croessmann, C. D.; Whitley, J. B.; Causey, R. A.

1990-04-01

Two serious problems with the use of graphite tiles on the ITER divertor are the limited lifetime due to erosion and the difficulty of replacing broken tiles inside the machine. Beryllium is proposed as an alternative low-Z armor material because the plasma spray process can be used to make in-situ repairs of eroded or damaged surfaces. Recent advances in plasma spray technology have produced beryllium coatings of 98% density with a 95% deposition efficiency and strong adhesion to the substrate. With existing technology, the entire active region of the ITER divertor surface could be coated with 2 mm of beryllium in less than 15 h using four small plasma spray guns. Beryllium also has other potential advantages over graphite, e.g., efficient gettering of oxygen, ten times less tritium inventory, reduced problems of transient fueling from D/T exchange and release, no runaway erosion cascades from self-sputtering, better adhesion of redeposited material, as well as higher strength, ductility, and fracture toughness than graphite. A 2-D finite element stress analysis was performed on a 3 mm thick Be tile brazed to an OFHC soft-copper saddle block, which was brazed to a high-strength copper tube. Peak stresses remained 50% below the ultimate strength for both brazing and in-service thermal stresses.

Using Field-Particle Correlations to Diagnose the Collisionless Damping of Plasma Turbulence

NASA Astrophysics Data System (ADS)

Howes, Gregory; Klein, Kristropher

2016-10-01

Plasma turbulence occurs ubiquitously throughout the heliosphere, yet our understanding of how turbulence governs energy transport and plasma heating remains incomplete, constituting a grand challenge problem in heliophysics. In weakly collisional heliospheric plasmas, such as the solar corona and solar wind, damping of the turbulent fluctuations occurs due to collisionless interactions between the electromagnetic fields and the individual plasma particles. A particular challenge in diagnosing this energy transfer is that spacecraft measurements are typically limited to a single point in space. Here we present an innovative field-particle correlation technique that can be used with single-point measurements to estimate the energization of the plasma particles due to the damping of the electromagnetic fields, providing vital new information about this how energy transfer is distributed as a function of particle velocity. This technique has the promise to transform our ability to diagnose the kinetic plasma physical mechanisms responsible for not only the damping of turbulence, but also the energy conversion in both collisionless magnetic reconnection and particle acceleration. The work has been supported by NSF CAREER Award AGS-1054061, NSF AGS-1331355, and DOE DE-SC0014599.

Study of evaporating the irradiated graphite in equilibrium low-temperature plasma

NASA Astrophysics Data System (ADS)

Bespala, E. V.; Novoselov, I. Yu.; Pavlyuk, A. O.; Kotlyarevskiy, S. G.

2018-01-01

The paper describes a problem of accumulation of irradiated graphite due to operation of uranium-graphite nuclear reactors. The main noncarbon contaminants that contribute to the overall activity of graphite elements are iso-topes 137Cs, 60Co, 90Sr, 36Cl, and 3H. A method was developed for processing of irradiated graphite ensuring the volu-metric decontamination of samples. The calculation results are presented for equilibrium composition of plasma-chemical reactions in systems "irradiated graphite-argon" and "irradiated graphite-helium" for a wide range of tem-peratures. The paper describes a developed mathematical model for the process of purification of a porous graphite surface treated by equilibrium low-temperature plasma. The simulation results are presented for the rate of sublimation of radioactive contaminants as a function of plasma temperature and plasma flow velocity when different plasma-forming gases are used. The extraction coefficient for the contaminant 137Cs from the outer side of graphite pores was calculated. The calculations demonstrated the advantages of using a lighter plasma forming gas, i.e., helium.

PREFACE: VII Conference on Low Temperature Plasma in the Processes of Functional Coating Preparation

NASA Astrophysics Data System (ADS)

Nail, Kashapov

2016-01-01

The VII All-Russian (with international participation) Scientific Technical Conference "Low-temperature plasma during the deposition of functional coatings" took place from 4-7 November 2015 at the Academy of Sciences of the Republic of Tatarstan and the Kazan Federal University. The conference was attended by over 150 people from Russia and abroad. The participants proposed a wide range of issues affecting the theoretical and experimental aspects of the problems of the physics of low-temperature plasma. We heard the reports of experts from leading universities and research organizations in the field of plasma physics: Moscow State University, St. Petersburg State University, MEPhI, Tomsk Polytechnic University, Institute of High Current Electronics SB RAS, etc. A series of works were devoted to the study of thin films obtained by low-temperature plasma. This year, work dedicated to the related field of heat mass transfer in multiphase media and low-temperature plasma was also presented. Of special interest were reports on the exploration of gas discharges with liquid electrolytic electrodes and the study of dusty plasmas. Kashapov Nail, D.Sc., professor (Kazan Federal University)

Development of High-Resolution UV-VIS Diagnostics for Space Plasma Simulation

NASA Astrophysics Data System (ADS)

Taylor, Andrew; Batishchev, Oleg

2012-10-01

Non-invasive far-UV-VIS plasma emission allows remote diagnostics of plasma, which is particularly important for space application. Accurate vacuum tank space plasma simulations require monochromators with high spectral resolution (better than 0.01A) to capture important details of atomic and ionic lines, such as Ly-alpha, etc. We are building a new system based on the previous work [1], and will discuss the development of a spectrometry system that combines a single-pass vacuum far-UV-NIR spectrometer and a tunable Fabry-Perot etalon. [4pt] [1] O. Batishchev and J.L. Cambier, Experimental Study of the Mini-Helicon Thruster, Air Force Research Laboratory Report, AFRL-RZ-ED-TR-2009-0020, 2009.

Minimum Fisher regularization of image reconstruction for infrared imaging bolometer on HL-2A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, J. M.; Liu, Y.; Li, W.

2013-09-15

An infrared imaging bolometer diagnostic has been developed recently for the HL-2A tokamak to measure the temporal and spatial distribution of plasma radiation. The three-dimensional tomography, reduced to a two-dimensional problem by the assumption of plasma radiation toroidal symmetry, has been performed. A three-dimensional geometry matrix is calculated with the one-dimensional pencil beam approximation. The solid angles viewed by the detector elements are taken into account in defining the chord brightness. And the local plasma emission is obtained by inverting the measured brightness with the minimum Fisher regularization method. A typical HL-2A plasma radiation model was chosen to optimize amore » regularization parameter on the criterion of generalized cross validation. Finally, this method was applied to HL-2A experiments, demonstrating the plasma radiated power density distribution in limiter and divertor discharges.« less

Fundamental experiment of ion thruster using ECR discharge

NASA Astrophysics Data System (ADS)

Yasui, Toshiaki; Kitayama, Jiro; Tahara, Hirokazu; Onoe, Ken-Ichi; Yoshikawa, Takao

A microwave ion thruster has the potential to overcome a lifetime problem of electric propulsion by eliminating electrodes. Two types of microwave ion thruster have been investigated to examine the operational characteristics. The one is the thruster using cavity-resonance microwave discharge, and the other is the thruster using Electron Cyclotron Resonance (ECR) discharge. Cavity-resonance microwave discharge produced plasmas by strong electric field in the resonant cavity and sustained plasmas at argon mass flow rates above 10 sccm. However, ECR discharge was capable of sustaining plasmas at lower mass flow rate, because ECR discharge efficiently produced plasmas by resonance absorption. From these generated microwave plasmas, ions were electrostatically extracted by two multiaperture grids. In ECR discharge, the maximum ion beam current of 75 mA and the highest mass utilization efficiency of 18.7% were achieved at a total extraction voltage of 950 V.

A new mathematical approach for shock-wave solution in a dusty plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, G.C.; Dwivedi, C.B.; Talukdar, M.

1997-12-01

The problem of nonlinear Burger equation in a plasma contaminated with heavy dust grains has been revisited. As discussed earlier [C. B. Dwivedi and B. P. Pandey, Phys. Plasmas {bold 2}, 9 (1995)], the Burger equation originates due to dust charge fluctuation dynamics. A new alternate mathematical approach based on a simple traveling wave formalism has been applied to find out the solution of the derived Burger equation, and the method recovers the known shock-wave solution. This technique, although having its own limitation, predicts successfully the salient features of the weak shock-wave structure in a dusty plasma with dust chargemore » fluctuation dynamics. It is emphasized that this approach of the traveling wave formalism is being applied for the first time to solve the nonlinear wave equation in plasmas. {copyright} {ital 1997 American Institute of Physics.}« less

Particle-In-Cell simulations of high pressure plasmas using graphics processing units

NASA Astrophysics Data System (ADS)

Gebhardt, Markus; Atteln, Frank; Brinkmann, Ralf Peter; Mussenbrock, Thomas; Mertmann, Philipp; Awakowicz, Peter

2009-10-01

Particle-In-Cell (PIC) simulations are widely used to understand the fundamental phenomena in low-temperature plasmas. Particularly plasmas at very low gas pressures are studied using PIC methods. The inherent drawback of these methods is that they are very time consuming -- certain stability conditions has to be satisfied. This holds even more for the PIC simulation of high pressure plasmas due to the very high collision rates. The simulations take up to very much time to run on standard computers and require the help of computer clusters or super computers. Recent advances in the field of graphics processing units (GPUs) provides every personal computer with a highly parallel multi processor architecture for very little money. This architecture is freely programmable and can be used to implement a wide class of problems. In this paper we present the concepts of a fully parallel PIC simulation of high pressure plasmas using the benefits of GPU programming.

Preliminary tests of the electrostatic plasma accelerator

NASA Technical Reports Server (NTRS)

Aston, G.; Acker, T.

1990-01-01

This report describes the results of a program to verify an electrostatic plasma acceleration concept and to identify those parameters most important in optimizing an Electrostatic Plasma Accelerator (EPA) thruster based upon this thrust mechanism. Preliminary performance measurements of thrust, specific impulse and efficiency were obtained using a unique plasma exhaust momentum probe. Reliable EPA thruster operation was achieved using one power supply.

Fibronectin in cell adhesion and migration via N-glycosylation

PubMed Central

Hsiao, Cheng-Te; Cheng, Hung-Wei; Huang, Chi-Ming; Li, Hao-Ru; Ou, Meng-Hsin; Huang, Jie-Rong; Khoo, Kay-Hooi; Yu, Helen Wenshin; Chen, Yin-Quan; Wang, Yang-Kao; Chiou, Arthur; Kuo, Jean-Cheng

2017-01-01

Directed cell migration is an important step in effective wound healing and requires the dynamic control of the formation of cell-extracellular matrix interactions. Plasma fibronectin is an extracellular matrix glycoprotein present in blood plasma that plays crucial roles in modulating cellular adhesion and migration and thereby helping to mediate all steps of wound healing. In order to seek safe sources of plasma fibronectin for its practical use in wound dressing, we isolated fibronectin from human (homo) and porcine plasma and demonstrated that both have a similar ability as a suitable substrate for the stimulation of cell adhesion and for directing cell migration. In addition, we also defined the N-glycosylation sites and N-glycans present on homo and porcine plasma fibronectin. These N-glycosylation modifications of the plasma fibronectin synergistically support the integrin-mediated signals to bring about mediating cellular adhesion and directed cell migration. This study not only determines the important function of N-glycans in both homo and porcine plasma fibronectin-mediated cell adhesion and directed cell migration, but also reveals the potential applications of porcine plasma fibronectin if it was applied as a material for clinical wound healing and tissue repair. PMID:29050309

[Research in theoretical nuclear physics]. [Annual progress report, July 1992--June 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapusta, J.I.

1993-12-31

The main subject of research was the physics of matter at energy densities greater than 0.15 GeV/fm{sup 3}. Theory encompasses the relativistic many-body/quantum field theory aspects of QCD and the electroweak interactions at these high energy densities, both in and out of thermal equilibrium. Applications range from neutron stars/pulsars to QCD and electroweak phase transitions in the early universe, from baryon number violation in cosmology to the description of nucleus-nucleus collisions at CERN and at Brookhaven. Recent activity to understand the properties of matter at energy densities where the electroweak W and Z boson degrees of freedom are important ismore » reported. This problem has applications to cosmology and has the potential to explain the baryon asymmetry produced in the big bang at energies where the particle degrees of freedom will soon be experimentally, probed. This problem is interesting for nuclear physics because of the techniques used in many-body, physics of nuclei and the quark-gluon plasma may be extended to this new problem. The was also interested in problems related to multiparticle production. This includes work on production of particles in heavy-ion collisions, the small x part, of the nuclear and hadron wave function, and multiparticle production induced by instantons in weakly coupled theories. These problems have applications in the heavy ion program at RHIC and the deep inelastic scattering experiments at HERA.« less

Interaction between La(III) and proteins on the plasma membrane of horseradish

NASA Astrophysics Data System (ADS)

Yang, Guang-Mei; Chu, Yun-Xia; Lv, Xiao-Fen; Zhou, Qing; Huang, Xiao-Hua

2012-06-01

Lanthanum (La) is an important rare earth element in the ecological environment of plant. The proteins on the plasma membrane control the transport of molecules into and out of cell. It is very important to investigate the effect of La(III) on the proteins on the plasma membrane in the plant cell. In the present work, the interaction between La(III) and proteins on the plasma membrane of horseradish was investigated using optimization of the fluorescence microscopy and fluorescence spectroscopy. It is found that the fluorescence of the complex system of protoplasts and 1-aniline Kenai-8-sulfonic acid in horseradish treated with the low concentration of La(III) is increased compared with that of the control horseradish. The opposite effect is observed in horseradish treated with the high concentration of La(III). These results indicated that the low concentration of La(III) can interact with the proteins on the plasma membrane of horseradish, causing the improvement in the structure of proteins on the plasma membrane. The high concentration of La(III) can also interact with the proteins on the plasma membrane of horseradish, leading to the destruction of the structure of proteins on the plasma membrane. We demonstrate that the proteins on the plasma membrane are the targets of La(III) action on plant cell.

Formation of high heat resistant coatings by using gas tunnel type plasma spraying.

PubMed

Kobayashi, A; Ando, Y; Kurokawa, K

2012-06-01

Zirconia sprayed coatings are widely used as thermal barrier coatings (TBC) for high temperature protection of metallic structures. However, their use in diesel engine combustion chamber components has the long run durability problems, such as the spallation at the interface between the coating and substrate due to the interface oxidation. Although zirconia coatings have been used in many applications, the interface spallation problem is still waiting to be solved under the critical conditions such as high temperature and high corrosion environment. The gas tunnel type plasma spraying developed by the author can make high quality ceramic coatings such as Al2O3 and ZrO2 coating compared to other plasma spraying method. A high hardness ceramic coating such as Al2O3 coating by the gas tunnel type plasma spraying, were investigated in the previous study. The Vickers hardness of the zirconia (ZrO2) coating increased with decreasing spraying distance, and a higher Vickers hardness of about Hv = 1200 could be obtained at a shorter spraying distance of L = 30 mm. ZrO2 coating formed has a high hardness layer at the surface side, which shows the graded functionality of hardness. In this study, ZrO2 composite coatings (TBCs) with Al2O3 were deposited on SS304 substrates by gas tunnel type plasma spraying. The performance such as the mechanical properties, thermal behavior and high temperature oxidation resistance of the functionally graded TBCs was investigated and discussed. The resultant coating samples with different spraying powders and thickness are compared in their corrosion resistance with coating thickness as variables. Corrosion potential was measured and analyzed corresponding to the microstructure of the coatings. High Heat Resistant Coatings, Gas Tunnel Type Plasma Spraying, Hardness,

Development and validation of a new method to simultaneously quantify triazoles in plasma spotted on dry sample spot devices and analysed by HPLC-MS.

PubMed

Baietto, Lorena; D'Avolio, Antonio; Marra, Cristina; Simiele, Marco; Cusato, Jessica; Pace, Simone; Ariaudo, Alessandra; De Rosa, Francesco Giuseppe; Di Perri, Giovanni

2012-11-01

Therapeutic drug monitoring (TDM) of triazoles is widely used in clinical practice to optimize therapy. TDM is limited by technical problems and cost considerations, such as sample storage and dry-ice shipping. We aimed to develop and validate a new method to analyse itraconazole, posaconazole and voriconazole in plasma spotted on dry sample spot devices (DSSDs) and to quantify them by an HPLC system. Extraction from DSSDs was done using n-hexane/ethyl acetate and ammonia solution. Samples were analysed using HPLC with mass spectrometry (HPLC-MS). Accuracy and precision were assayed by inter- and intra-day validation. The stability of triazoles in plasma spotted on DSSDs was investigated at room temperature for 1 month. The method was compared with a validated standard HPLC method for quantification of triazoles in human plasma. Mean inter- and intra-day accuracy and precision were <15% for all compounds. Triazoles were stable for 2 weeks at room temperature. The method was linear (r(2) > 0.999) in the range 0.031-8 mg/L for itraconazole and posaconazole, and 0.058-15 mg/L for voriconazole. High sensitivity was observed; limits of detection were 0.008, 0.004 and 0.007 mg/L for itraconazole, posaconazole and voriconazole, respectively. A high degree of correlation (r(2) > 0.94) was obtained between the DSSD method and the standard method of analysis. The method that we developed and validated to quantify triazoles in human plasma spotted on DSSDs is accurate and precise. It overcomes problems related to plasma sample storage and shipment, allowing TDM to be performed in a cheaper and safer manner.

Self-similar expansion of adiabatic electronegative dusty plasma

NASA Astrophysics Data System (ADS)

Shahmansouri, M.; Bemooni, A.; Mamun, A. A.

2017-12-01

The self-similar expansion of an adiabatic electronegative dusty plasma (consisting of inertialess adiabatic electrons, inertialess adiabatic ions and inertial adiabatic negatively charged dust fluids) is theoretically investigated by employing the self-similar approach. It is found that the effects of the plasma adiabaticity (represented by the adiabatic index ) and dusty plasma parameters (determined by dust temperature and initial dust population) significantly modify the nature of the plasma expansion. The implications of our results are expected to play an important role in understanding the physics of the expansion of space and laboratory electronegative dusty plasmas.

Expansion of a multicomponent current-carrying plasma jet into vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasov, V. I.; Paperny, V. L., E-mail: paperny@math.isu.runnet.ru

An expression for the ion−ion coupling in a multicomponent plasma jet is derived for an arbitrary ratio between the thermal and relative velocities of the components. The obtained expression is used to solve the problem on the expansion of a current-carrying plasma microjet emitted from the cathode surface into vacuum. Two types of plasmas with two ion components are analyzed: (i) plasma in which the ion components of equal masses are in the charge states Z{sub 1}= +1 and Z{sub 2}= +2 and (ii) plasma with ions in equal charge states but with the mass ratio m{sub 1}/m{sub 2} =more » 2. It is shown that, for such plasmas, the difference between the velocities of the plasma components remains substantial (about 10% of the average jet velocity in case (i) and 15% in case (ii)) at distances of several centimeters from the emission center, where it can be measured experimentally, provided that its initial value at the emitting cathode surface exceeds a certain threshold. This effect is investigated as a function of the mass ratio and charge states of the ion components.« less

Synthesis of ultrafine Si3N4 powder in RF-RF plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Michitaka; Nishio, Hiroaki

1991-10-01

A newly designed plasma-CVD apparatus mounted with the RF-RF type plasma torch was introduced to synthesize ultrafine powders of silicon nitride (Si3N4). The RF-RF plasma system (the combination of a main (lower) and controlling (upper) RF plasma) improved the stability of simple RF plasma and solved the impurity problem of dc-RF hybrid plasma. The reaction of SiCl4 and NH3, which were radially injected into the tail flames of the upper and lower plasmas, respectively, yielded near-stoichiometric amorphous powders of Si3N4. The nitrogen content in the products largely depended on the flow rate of the quenching gas, a mixture of NH3more » (reactant) and H2. The oxygen content and metal impurities are 2-3 wt pct and less than 200 ppm, respectively. The powder particles had an average diameter of about 15 nm with a narrow size distribution, and showed extreme air sensitivity. Conspicuous crystallazation and particle growth occurred when heated at temperatures above 1400 C. These results suggested that the RF-RF system was a potential reactor for the synthesis of ultrafine powders with excellent sinterability at relatively low temperatures. 9 refs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandra, Mani; Gammie, Charles F.; Foucart, Francois, E-mail: manic@illinois.edu, E-mail: gammie@illinois.edu, E-mail: fvfoucart@lbl.gov

Hot, diffuse, relativistic plasmas such as sub-Eddington black-hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects such as heat conduction and viscosity can be important in a collisionless plasma and will potentially alter the dynamics and radiative properties of the flow from that in ideal fluid models; we refer to models that include these processes as Extended GRMHD. Here we describe a new conservative code, grim, that enables all of the above and additional physics to be efficiently incorporated. grim combines time evolution and primitive variablemore » inversion needed for conservative schemes into a single step using an algorithm that only requires the residuals of the governing equations as inputs. This algorithm enables the code to be physics agnostic as well as flexibility regarding time-stepping schemes. grim runs on CPUs, as well as on GPUs, using the same code. We formulate a performance model and use it to show that our implementation runs optimally on both architectures. grim correctly captures classical GRMHD test problems as well as a new suite of linear and nonlinear test problems with anisotropic conduction and viscosity in special and general relativity. As tests and example applications, we resolve the shock substructure due to the presence of dissipation, and report on relativistic versions of the magneto-thermal instability and heat flux driven buoyancy instability, which arise due to anisotropic heat conduction, and of the firehose instability, which occurs due to anisotropic pressure (i.e., viscosity). Finally, we show an example integration of an accretion flow around a Kerr black hole, using Extended GRMHD.« less

Direct trace-elemental analysis of urine samples by laser ablation-inductively coupled plasma mass spectrometry after sample deposition on clinical filter papers.

PubMed

Aramendía, Maite; Rello, Luis; Vanhaecke, Frank; Resano, Martín

2012-10-16

Collection of biological fluids on clinical filter papers shows important advantages from a logistic point of view, although analysis of these specimens is far from straightforward. Concerning urine analysis, and particularly when direct trace elemental analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) is aimed at, several problems arise, such as lack of sensitivity or different distribution of the analytes on the filter paper, rendering obtaining reliable quantitative results quite difficult. In this paper, a novel approach for urine collection is proposed, which circumvents many of these problems. This methodology consists on the use of precut filter paper discs where large amounts of sample can be retained upon a single deposition. This provides higher amounts of the target analytes and, thus, sufficient sensitivity, and allows addition of an adequate internal standard at the clinical lab prior to analysis, therefore making it suitable for a strategy based on unsupervised sample collection and ulterior analysis at referral centers. On the basis of this sampling methodology, an analytical method was developed for the direct determination of several elements in urine (Be, Bi, Cd, Co, Cu, Ni, Sb, Sn, Tl, Pb, and V) at the low μg L(-1) level by means of LA-ICPMS. The method developed provides good results in terms of accuracy and LODs (≤1 μg L(-1) for most of the analytes tested), with a precision in the range of 15%, fit-for-purpose for clinical control analysis.

Atomic Precision Plasma Processing - Modeling Investigations

NASA Astrophysics Data System (ADS)

Rauf, Shahid

2016-09-01

Sub-nanometer precision is increasingly being required of many critical plasma processes in the semiconductor industry. Some of these critical processes include atomic layer etch and plasma enhanced atomic layer deposition. Accurate control over ion energy and ion / radical composition is needed during plasma processing to meet the demanding atomic-precision requirements. While improvements in mainstream inductively and capacitively coupled plasmas can help achieve some of these goals, newer plasma technologies can expand the breadth of problems addressable by plasma processing. Computational modeling is used to examine issues relevant to atomic precision plasma processing in this paper. First, a molecular dynamics model is used to investigate atomic layer etch of Si and SiO2 in Cl2 and fluorocarbon plasmas. Both planar surfaces and nanoscale structures are considered. It is shown that accurate control of ion energy in the sub-50 eV range is necessary for atomic scale precision. In particular, if the ion energy is greater than 10 eV during plasma processing, several atomic layers get damaged near the surface. Low electron temperature (Te) plasmas are particularly attractive for atomic precision plasma processing due to their low plasma potential. One of the most attractive options in this regard is energetic-electron beam generated plasma, where Te <0.5 eV has been achieved in plasmas of molecular gases. These low Te plasmas are computationally examined in this paper using a hybrid fluid-kinetic model. It is shown that such plasmas not only allow for sub-5 eV ion energies, but also enable wider range of ion / radical composition. Coauthors: Jun-Chieh Wang, Jason Kenney, Ankur Agarwal, Leonid Dorf, and Ken Collins.