Special issue on transient plasmas
NASA Astrophysics Data System (ADS)
Bailey, James; Hoarty, David; Mancini, Roberto; Yoneda, Hitoki
2015-11-01
This special issue of Journal of Physics B: Atomic, Molecular and Optical Physics is dedicated to the "spectroscopy of transient plasmas" covering plasma conditions produced by a range of pulsed laboratory sources including short and long pulse lasers, pulsed power devices, and free electron lasers (FELs). The full range of plasma spectroscopy up to high energy bremsstrahlung radiation, including line broadening analysis for application to data recorded with the ChemCam instrument on the Mars Science Laboratory rover Curiosity, is covered. This issue is timely as advances in optical lasers and x-ray FELs (XFEL) are enabling transient plasma to be probed at higher energies and shorter durations than ever before. New XFEL facilities being commissioned in Europe and Asia are adding to those operating in the US and Japan and the ELI high power laser project in Europe, due to open this year, will provide short pulse lasers of unprecedented power. This special issue represents a snapshot of the theoretical and experimental research in dense plasmas, electron kinetics, laser-induced breakdown spectroscopy of low temperature plasmas, inertial confinement fusion and non-equilibrium atomic physics using spectroscopy to diagnose plasmas produced by optical lasers, XFELs and pulsed-power machines.
EDITORIAL: Special issue on plasmas with liquids Special issue on plasmas with liquids
NASA Astrophysics Data System (ADS)
Leys, C.; Locke, B. R.; Tachibana, K.
2011-06-01
In recent years, plasmas generated in and with liquids have attracted considerable interest because of their great potential for applications in various fields such as industrial, environmental and biomedical technologies. Special sessions on plasmas with liquids have been arranged in many large-scale international conferences, but few special meetings devoted only to these topics have been held. Therefore, we organized the International Workshop on Plasmas with Liquids (IWPL) in March 2010 in Matsuyama, Ehime, Japan. Although it was a small workshop with about 90 participants from nine countries, 54 papers were presented within a period of three days. Taking advantage of this opportunity, we organized publication of a special issue on plasmas with liquids. Invited lecturers and selected presenters from the IWPL were invited to submit original peer-reviewed articles based on their presentations for this special issue. In order to expand the coverage of this topic, a call for papers was also announced broadly for non-participants of IWPL who also work in this field. In this special issue we have collected original papers related to the fundamental science of discharge phenomena in and with liquids, and to the resulting technological applications. Emphasis is placed on research into our understanding the physical, chemical and biological processes in discharges interacting with liquids. However, some papers with a focus on the potential applications of discharges in liquids are also included. The papers published in this special issue cover the frontiers of this new and growing field of plasma science and technology, and may encourage further advances in both fundamental research and application. We acknowledge the authors for their contributions.
Specialized minimal PDFs for optimized LHC calculations
NASA Astrophysics Data System (ADS)
Carrazza, Stefano; Forte, Stefano; Kassabov, Zahari; Rojo, Juan
2016-04-01
We present a methodology for the construction of parton distribution functions (PDFs) designed to provide an accurate representation of PDF uncertainties for specific processes or classes of processes with a minimal number of PDF error sets: specialized minimal PDF sets, or SM-PDFs. We construct these SM-PDFs in such a way that sets corresponding to different input processes can be combined without losing information, specifically as regards their correlations, and that they are robust upon smooth variations of the kinematic cuts. The proposed strategy never discards information, so that the SM-PDF sets can be enlarged by the addition of new processes, until the prior PDF set is eventually recovered for a large enough set of processes. We illustrate the method by producing SM-PDFs tailored to Higgs, top-quark pair, and electroweak gauge boson physics, and we determine that, when the PDF4LHC15 combined set is used as the prior, around 11, 4, and 11 Hessian eigenvectors, respectively, are enough to fully describe the corresponding processes.
Quantum states of confined hydrogen plasma species: Monte Carlo calculations
NASA Astrophysics Data System (ADS)
Micca Longo, G.; Longo, S.; Giordano, D.
2015-12-01
The diffusion Monte Carlo method with symmetry-based state selection is used to calculate the quantum energy states of \\text{H}2+ confined into potential barriers of atomic dimensions (a model for these ions in solids). Special solutions are employed, permitting one to obtain satisfactory results with rather simple native code. As a test case, {{}2}{{\\Pi}u} and {{}2}{{\\Pi}g} states of \\text{H}2+ ions under spherical confinement are considered. The results are interpreted using the correlation of \\text{H}2+ states to atomic orbitals of H atoms lying on the confining surface and perturbation calculations. The method is straightforwardly applied to cavities of any shape and different hydrogen plasma species (at least one-electron ones, including H) for future studies with real crystal symmetries.
Calculation of Electromagnetic Quasistatic Plasma Waves*
NASA Astrophysics Data System (ADS)
Cooley, J.; Antonsen, T. M., Jr.; Mori, W.
2001-10-01
Plasma based particle acceleration requires the generation of plasma wave wakes which maintain their coherence over long distances. For example in Laser Wake Field Acceleration (LWFA) schemes the laser pulse must propagate tens of centimeters, which coresponds to many Rayleigh lengths, and in Plasma Wake Field Acceleration (PWFA) the particle beam must be propagated many meters. These wakes, and their effect on the driver (Laser or particle beam) can be simulated efficiently in the quasistatic approximation [1]. In this approximation the driver does not evolve during the time a plasma electron spends in the driver. We discuss here various numerical algorithms for determining the full electromagnetic wake in this case. The problem is complicated in that the particle trajectories and wake fields must be determined iteratively when the wake becomes electromagnetic. The effect of different choices for the gauge will be presented. [1] "Kinetic Modeling of Intense, Short Laser Pulses Propagating in Tenuous Plasma", P. Mora and T. M. Antonsen Jr., Phys Plasma 4, 217 (1997) *Work supported by NSF and DOE
The calculation of thermophysical properties of nickel plasma
Apfelbaum, E. M.
2015-09-15
The thermophysical properties of Nickel plasma have been calculated for the temperatures 10–60 kK and densities less than 1 g/cm{sup 3}. These properties are the pressure, internal energy, heat capacity, and the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermal power). The thermodynamic values have been calculated by means of the chemical model, which also allows one to obtain the ionic composition of considered plasma. The composition has been used to calculate the electronic transport coefficients within the relaxation time approximation. The results of the present investigation have been compared with the calculations of other researchers and available data of measurements.
Special issue on the spectroscopy of transient plasmas
NASA Astrophysics Data System (ADS)
Bailey, James; Hoarty, David; Mancini, Roberto; Yoneda, Hitoki
2015-01-01
Experimental and theoretical papers are invited for a special issue of Journal of Physics B: Atomic, Molecular and Optical Physics on Spectroscopy of Transient Plasmas, covering plasma conditions produced by pulsed laboratory sources including for example, short and long pulse lasers; pulsed power devices; FELs; XFELs and ion beams. The full range of plasma spectroscopy from the optical range up to high energy bremsstrahlung radiation will be covered. The deadline for submitting to this special issue is 1 March 2015. (Expected web publication: autumn 2015). Late submissions will be considered for the journal, but may not be included in the special issue. All submitted articles will be fully refereed to the journal's usual high standards. Upon publication, the issue will be widely promoted to the atomic, molecular and optical physics community, ensuring that your work receives maximum visibility. Articles should be submitted at http://mc04.manuscriptcentral.com/jphysb-iop. Should you have any questions regarding the preparation of manuscripts or the suitability of your work for this Issue, please do not hesitate to contact the J. Phys. B: At. Mol. Opt. Editorial team (jphysb@iop.org). We look forward to hearing from you and hope that we can welcome you as a contributing author.
Calculation of fusion product angular correlation coefficients for fusion plasmas
Murphy, T.J.
1987-08-01
The angular correlation coefficients for fusion products are calculated in the cases of Maxwellian and beam-target plasmas. Measurement of these coefficients as a localized ion temperature or fast-ion diagnostic is discussed. 8 refs., 7 figs., 1 tab.
Representation of the Geosynchronous Plasma Environment in Spacecraft Charging Calculations
NASA Technical Reports Server (NTRS)
Davis, V. A.; Mandell, M. J.; Thomsen, M. F.
2006-01-01
Historically, our ability to predict and postdict spacecraft surface charging has been limited by the characterization of the plasma environment. One difficulty lies in the common practice of fitting the plasma data to a Maxwellian or Double Maxwellian distribution function, which may not represent the data well for charging purposes. We use electron and ion flux spectra measured by the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzer (MPA) to examine how the use of different spectral representations of the charged particle environment in computations of spacecraft potentials during magnetospheric substorms affects the accuracy of the results. We calculate the spacecraft potential using both the measured fluxes and several different fits to these fluxes. These measured fluxes have been corrected for the difference between the measured and calculated potential. The potential computed using the measured fluxes and the best available material properties of graphite carbon, with a secondary electron escape fraction of 81%, is within a factor of three of the measured potential for 87% of the data. Potentials calculated using a Kappa function fit to the incident electron flux distribution function and a Maxwellian function fit to the incident ion flux distribution function agree with measured potentials nearly as well as do potentials calculated using the measured fluxes. Alternative spectral representations gave less accurate estimates of potential. The use of all the components of the net flux, along with spacecraft specific average material properties, gives a better estimate of the spacecraft potential than the high energy flux alone.
Calculation and application of combined diffusion coefficients in thermal plasmas.
Murphy, Anthony B
2014-01-01
The combined diffusion coefficient method is widely used to treat the mixing and demixing of different plasma gases and vapours in thermal plasmas, such as welding arcs and plasma jets. It greatly simplifies the treatment of diffusion for many gas mixtures without sacrificing accuracy. Here, three subjects that are important in the implementation of the combined diffusion coefficient method are considered. First, it is shown that different expressions for the combined diffusion coefficients, arising from different definitions for the stoichiometric coefficients that assign the electrons to the two gases, are equivalent. Second, an approach is presented for calculating certain partial differential terms in the combined temperature and pressure diffusion coefficients that can cause difficulties. Finally, a method for applying the combined diffusion coefficients in computational models, which typically require diffusion to be expressed in terms of mass fraction gradients, is given. PMID:24603457
Calculation and application of combined diffusion coefficients in thermal plasmas
Murphy, Anthony B.
2014-01-01
The combined diffusion coefficient method is widely used to treat the mixing and demixing of different plasma gases and vapours in thermal plasmas, such as welding arcs and plasma jets. It greatly simplifies the treatment of diffusion for many gas mixtures without sacrificing accuracy. Here, three subjects that are important in the implementation of the combined diffusion coefficient method are considered. First, it is shown that different expressions for the combined diffusion coefficients, arising from different definitions for the stoichiometric coefficients that assign the electrons to the two gases, are equivalent. Second, an approach is presented for calculating certain partial differential terms in the combined temperature and pressure diffusion coefficients that can cause difficulties. Finally, a method for applying the combined diffusion coefficients in computational models, which typically require diffusion to be expressed in terms of mass fraction gradients, is given. PMID:24603457
Parametric calculations of plasma jets generated by microdischarges
NASA Astrophysics Data System (ADS)
Foletto, M.; Boeuf, J. P.; Pitchford, L. C.
2014-10-01
``Guided streamers'' or ``plasma jets'' can be generated in open air by applying rf or impulse voltages to a microdischarge through which there is a flow of helium. For flow conditions such that a helium column surrounded by air extends some distance (centimeters) past the exit of the microdischarge, a plasma jet can be initiated. Previous works have shown that this is essentially a streamer propagating in the easily-ionized helium column and impeded from branching by the surrounding air. For many applications, it is of interest to understand the parameters controlling the properties of the plasma jet. To this end, we present results from a series of parametric calculations using our previously published model to identify the influence of the microdischarge configuration on the generation, propagation, and properties of the plasma jet. We focus mainly on a geometry with hollow, concentric electrodes separated by a dielectric tube corresponding to the experiments of Douat et al., and we vary the dimensions and relative off-set of the electrodes, applying an impulse voltage or the experimental waveform to the inner electrode. For the same applied voltage waveform, parameters which influence the electric field and electron density in the plasma jet are the dielectric permittivity, the tube diameter, and the dielectric length. Support by the French National Research Agency project PAMPA.
Representation of the Geosynchronous Plasma Environment for Spacecraft Charging Calculations
NASA Technical Reports Server (NTRS)
Davis, V. A.; Mandell, M. J.; Thomsen, M. F.
2004-01-01
Historically, our ability to predict and postdict surface charging has suffered from both a lack of reliable secondary emission and backscattered electron yields and poor characterization of the plasma environment. One difficulty lies in the common practice of fitting the plasma data to a Maxwellian or Double Maxwellian distribution function, which may not represent the data well for charging purposes. For 13 years Los Alamos National Laboratory (LANL) has been accumulating measurements of electron and proton spectra from Magnetospheric Plasma Analyzer (MPA) instruments aboard a series of geosynchronous satellites. These data provide both a plasma characterization and the potential of the instrument ground. We use electron and ion flux spectra measured by the LANL MPA to examine how the use of different spectral representations of the charged particle environment in computations of spacecraft potentials during magnetospheric substorms affects the accuracy of the results. We calculate the spacecraft potential using both the measured fluxes and several different fits to these fluxes. These flux measurements and fits have been corrected for the difference between the measured and calculated potential. The potentials computed using the measured fluxes, the best available material properties of graphite carbon, and a secondary electron escape fraction of 81%, are within a factor of three of the measured potential for nearly all the data. Using a Kappa fit to the electron distribution function and a Maxwellian fit to the ion distribution function gives agreement similar to the calculations using the actual data. Alternative spectral representations, including Maxwellian and double Maxwellian for both species, lead to less satisfactory agreement between predicted and measured potentials.
Iterative Calculation of Plasma Density from a Cylindrical Probe Characteristic
NASA Astrophysics Data System (ADS)
Xu, Zhenfeng; Lu, Wenqi
2013-08-01
A novel method is proposed for treating cylindrical probe characteristics to obtain plasma density. The method consists of exponential extrapolation of the transitional part of the I-V curve to the floating potential for the ion saturation current, other than the existing theories which use the ion branch, and an iterative sheath thickness correction procedure for improved accuracy. The method was tested by treating Langmuir probe I-V characteristics obtained from inductively coupled Ar discharges at various pressures, and comparing the present results with those deduced by existing theories. It was shown that the plasma densities obtained by the present method are in good agreement with those calculated by the Allen-Boyd-Reynolds (ABR) theory, suggesting the effectiveness of the proposed method. Without need of manual setting and adjustment of fitting parameters, the method may be suitable for automatic and real time processing of probe characteristics.
Radio Frequency Field Calculations for Plasma Heating Simulations in VASIMR
NASA Astrophysics Data System (ADS)
Ilin, A. V.; Díaz, F. R. Chang; Squire, J. P.; Carter, M. D.
2002-01-01
(VASIMR)1 is plasma heating by ion-cyclotron RF heating (ICRF). Mathematical simulation helps to design an ICRF antenna, i.e. make maximal absorption of RF power into the plasma in the resonance area. Another goal of a particle simulation is design of a magnetic nozzle and optimize the performance of VASIMR2. field in the plasma, 2) ion density and velocity, 3) ion-cyclotron radio-frequency electromagnetic field. The assumptions of quasineutral and collisionless plasma are based on the range of operating VASIMR parameters. Carlo simulations for systems of million of particles in a reasonable time and without the need for a powerful supercomputer. The particle to grid weighting method is used for calculating the ion density, which is used for recalculation of the electric potential and RF field. dimensional problem to a weighted sum over two-dimensional solutions. Absorption is introduced in the cold plasma model by adding an imaginary collision frequency to the RF driven frequency, which is equivalent to adding an imaginary particle mass in the dielectric tensor elements. static and RF fields using the VASIMR code2. The VASIMR and EMIR codes are then iterated to estimate the ICRF effects on the plasma density. The iteration is performed by calculating the RF fields with the EMIR code, and using these fields to follow nonlinear ion trajectories with the VASIMR code on the gyro-frequency time scale. The ion trajectories are used to generate RF power absorption values and a density input for the next EMIR calculation. The codes are iterated until the density profile becomes reasonably stable, then the collisional absorption parameter in the EMIR code is adjusted and the iteration is continued until the power deposited by the RF system matches the power absorbed by the ion trajectories in a global sense. electric field. The solved algebraic system of equations is represented by ill-conditioned 18-diagonal matrix with complex elements. Since early development of the
General Linear Rf-Current Drive Calculation in Toroidal Plasma
NASA Astrophysics Data System (ADS)
Smirnov, A. P.; Harvey, R. W.; Prater, R.
2009-04-01
A new general linear calculation of RF current drive has been implemented in the GENRAY all-frequencies RF ray tracing code. This is referred to as the ADJ-QL package, and is based on the Karney, et al. [1] relativistic Green function calculator, ADJ, generalized to non-circular plasmas in toroidal geometry, and coupled with full, bounce-averaged momentum-space RF quasilinear flux [2] expressions calculated at each point along the RF ray trajectories. This approach includes momentum conservation, polarization effects and the influence of trapped electrons. It is assumed that the electron distribution function remains close to a relativistic Maxwellian function. Within the bounds of these assumptions, small banana width, toroidal geometry and low collisionality, the calculation is applicable for all-frequencies RF electron current drive including electron cyclotron, lower hybrid, fast waves and electron Bernstein waves. GENRAY ADJ-QL calculations of the relativistic momentum-conserving current drive have been applied in several cases: benchmarking of electron cyclotron current drive in ITER against other code results; and electron Bernstein and high harmonic fast wave current drive in NSTX. The impacts of momentum conservation on the current drive are also shown for these cases.
Errors in calculated oncotic pressure of dog plasma.
Gabel, J C; Scott, R L; Adair, T H; Drake, R E; Traber, D L
1980-12-01
Several equations to calculate plasma oncotic pressure (pi) from the total protein concentration (C) have been previously described. These equations were derived empirically from samples with a wide range of C obtained by diluting or concentrating normal plasma samples. To test these equations over a range of naturally occurring C, we measured C and pi of plasma samples from 40 dogs. C ranged from 5.3 to 8.7 g/dl and averaged 6.5 +/- 0.1 (mean +/- SE) and pi averaged 17.9 +/- 0.3 mmHg. The regression equation was pi = 78.14 + 1.67 C (r = 0.74). pi increased with C much less than predicted with the commonly used equations. The albumin-to-globulin concentration ratios (A/G), determined in 27 of the dogs, decreased with increasing C (A/G = 1.56-0.128 C, r = 0.62). The lower A/G at the higher C's could cause the lower than predicted increase in pi with C, because the equations were developed from data in which A/G was constant. PMID:7446756
Quantum-Chemical Calculation of Carbododecahedron Formation in Carbon Plasma.
Poklonski, Nikolai A; Ratkevich, Sergey V; Vyrko, Sergey A
2015-08-27
The ground state of the molecule consisting of 10 carbon atoms in C10(rg) "ring" conformation and the energy of its metastable C10(st) "star" conformation are reported. The reaction coordinate for the isomeric transition C10(st) → C10(rg) was calculated using density functional theory (DFT) with UB3LYP/6-31G(d,p). It was established that a 5-fold symmetry axis is conserved in this isomeric transition. The total energy of the ring isomer is by 10.33 eV (9.16 eV as zero-point energy corrected) lower than that of the star isomer. The energy barrier for the transition from the metastable star state to the ring state is 2.87 eV (3.57 eV as zero-point energy corrected). An analysis of possible chemical reactions in carbon plasma involving C10(st) and C10(rg) and leading to the formation of C20 fullerenes was performed. It was revealed that the presence of the C10(st) conformation in the reaction medium is a necessary condition for C20 fullerene formation. It was shown that the presence of hydrogen atoms in carbon plasma and UV radiation accelerate the C10(st) → C10(rg) transition and thus suppress the C20 fullerene formation. PMID:26267290
Preface to Special Topic: Plasmas for Medical Applications
Keidar, Michael; Robert, Eric
2015-12-15
Intense research effort over last few decades in low-temperature (or cold) atmospheric plasma application in bioengineering led to the foundation of a new scientific field, plasma medicine. Cold atmospheric plasmas (CAP) produce various chemically reactive species including reactive oxygen species (ROS) and reactive nitrogen species (RNS). It has been found that these reactive species play an important role in the interaction of CAP with prokaryotic and eukaryotic cells triggering various signaling pathways in cells.
Preface to Special Topic: Plasmas for Medical Applications
NASA Astrophysics Data System (ADS)
Keidar, Michael; Robert, Eric
2015-12-01
Intense research effort over last few decades in low-temperature (or cold) atmospheric plasma application in bioengineering led to the foundation of a new scientific field, plasma medicine. Cold atmospheric plasmas (CAP) produce various chemically reactive species including reactive oxygen species (ROS) and reactive nitrogen species (RNS). It has been found that these reactive species play an important role in the interaction of CAP with prokaryotic and eukaryotic cells triggering various signaling pathways in cells.
The Martian Plasma Environment: Model Calculations and Observations
NASA Astrophysics Data System (ADS)
Lichtenegger, H. I. M.; Dubinin, E.; Schwingenschuh, K.; Riedler, W.
Based on a modified version of the model of an induced martian magnetosphere developed by Luhmann (1990), the dynamics and spatial distribution of different planetary ion species is examined. Three main regions are identified: A cloud of ions travelling along cycloidal trajectories, a plasma mantle and a plasma sheet. The latter predominantly consists of oxygen ions of ionospheric origin with minor portions of light particles. Comparison of model results with Phobos-2 observations shows reasonable agreement.
NASA Astrophysics Data System (ADS)
de Jong, Maarten; Qi, Liang; Olmsted, David L.; van de Walle, Axel; Asta, Mark
2016-03-01
A method is described for calculating the energetics of planar defects in alloys based on the special-quasirandom-structure (SQS) approach. We examine the accuracy of the approach employing atomistic calculations based on a classical embedded-atom-method (EAM) interatomic potential for hexagonal close packed (hcp) alloys, for which benchmark results can be obtained by direct configurational averaging. The results of these calculations demonstrate that the SQS-based approach can be employed to derive the concentration dependence of the energies of twin boundaries, unstable stacking faults, and surfaces to within an accuracy of approximately 10%. The SQS considered in this study contain up to 72 atoms and hence are small enough to be considered in first-principles density-functional-theory (DFT) based calculations. The application of the SQS-based approach in direct DFT-based calculations is demonstrated in a study of the concentration dependence of interfacial energies for {11 2 ¯1 } twins in hcp Ti-Al alloys.
NASA Astrophysics Data System (ADS)
Howling, A. A.; Guittienne, Ph; Jacquier, R.; Furno, I.
2015-12-01
The coupling between an inductive source and the plasma determines the power transfer efficiency and the reflected impedance in the primary circuit. Usually, the plasma coupling is analysed by means of a transformer equivalent circuit, where the plasma inductance and resistance are estimated using a global plasma model. This paper shows that, for planar RF antennas, the mutual inductance between the plasma and the primary circuit can be calculated using partial inductances and the complex image method, where the plasma coupling is determined in terms of the plasma skin depth and the distance to the plasma. To introduce the basic concepts, the mutual inductance is calculated here for a linear conductor parallel to the plasma surface. In the accompanying paper part II Guittienne et al (2015 Plasma Sources Sci. Technol. 24 065015), impedance measurements on a RF resonant planar plasma source are modeled using an impedance matrix where the plasma-antenna mutual impedances are calculated using the complex image method presented here.
Iterative methods for plasma sheath calculations: Application to spherical probe
NASA Technical Reports Server (NTRS)
Parker, L. W.; Sullivan, E. C.
1973-01-01
The computer cost of a Poisson-Vlasov iteration procedure for the numerical solution of a steady-state collisionless plasma-sheath problem depends on: (1) the nature of the chosen iterative algorithm, (2) the position of the outer boundary of the grid, and (3) the nature of the boundary condition applied to simulate a condition at infinity (as in three-dimensional probe or satellite-wake problems). Two iterative algorithms, in conjunction with three types of boundary conditions, are analyzed theoretically and applied to the computation of current-voltage characteristics of a spherical electrostatic probe. The first algorithm was commonly used by physicists, and its computer costs depend primarily on the boundary conditions and are only slightly affected by the mesh interval. The second algorithm is not commonly used, and its costs depend primarily on the mesh interval and slightly on the boundary conditions.
Calculation of radiative properties of nonequilibrium hydrogen plasma
NASA Technical Reports Server (NTRS)
Park, C.
1979-01-01
A computer program called NEQRAP is described that calculates the radiative properties of nonequilibrium ionized hydrogen. From the given electron temperature, electron density, and atom density values (which do not necessarily satisfy the equilibrium relationship) and intensities of incident radiation, the non-Boltzmann populations of electronic states are computed by solving the equation of quasi-steady-state population distribution. Emission and absorption coefficients are determined as functions of wavelength by invoking the principle of detailed balance between the upper and lower states of each radiative transition. Radiative transport through the medium is computed assuming a one-dimensional uniform slab. The rate of ionic reaction is also computed. When used on a sample case, the program shows that there is a large difference between the calculated intensities of radiation emitted by a bulk of equilibrium and nonequilibrium hydrogen. The accuracy of the program is estimated to be better than 10%.
An Exact Calculation of Electron-Ion Energy Splitting in a Hot Plasma
Singleton, Robert L
2012-09-10
In this brief report, I summarize the rather involved recent work of Brown, Preston, and Singleton (BPS). In Refs. [2] and [3], BPS calculate the energy partition into ions and electrons as a charged particle traverses a non-equilibrium two-temperature plasma. These results are exact to leading and next-to-leading order in the plasma coupling g, and are therefore extremely accurate in a weakly coupled plasma. The new BPS calculations are compared with the more standard work of Fraley et al. [12]. The results differ substantially at higher temperature when T{sub I} {ne} T{sub e}.
Systematic methods for calculation of the dielectric properties of arbitrary plasmas
NASA Technical Reports Server (NTRS)
Robinson, P. A.
1990-01-01
In the novel approach presented for calculating the dispersion integrals needed for determining plasma dielectric properties, the dispersion integrals for an arbitrary distortion function with a continuous derivative are systematically expanded in terms of a set of orthogonal functions whose corresponding dispersion functions are already known. This general approach is, on the one hand, implemented for unmagnetized plasmas, and on the other generalized to treat relativistic and magnetized plasmas. The method allows the systematic and efficient calculation of dispersion integrals, for the cases of either real or complex arguments.
Temperature profile measurements and equilibrium calculations in a non-neutral plasma.
NASA Astrophysics Data System (ADS)
Hart, Grant W.; Peterson, Bryan G.
2004-11-01
In 1992 Eggleston, et.al.^1 developed a technique for measuring the radial temperature profile in a pure electron plasma by partially dumping the plasma onto a charge collector. They used a model which described the plasma as a flat-ended cylinder to determine the midplane potential of the plasma and ignored the plasma's contribution to the confining potential hill. These assumptions are fine if the plasma is long and the ring to which the confining potential is applied is also fairly long. For short plasmas and short confining rings, a more general calculation is needed. In this paper we present a variation on the standard equilibrium calculation that allows us to use dumped charge vs. confining potential data to calculate the temperature profile of a pure electron plasma. The fact that part of the Maxwellian velocity distribution has escaped forces a generalization of the form of the equilibrium condition from the usual e^-q φ/kT. Experimental data and results will be discussed. A simplified measurement similar to the simple r=0 velocity-tail measurement of Eggleston will also be discussed. ^1D.L.Eggleston, C.F. Driscoll, B.R. Beck, A.W. Hyatt and J.H. Malmberg, Phys. Fluids B 4, 3432 (1992).
A simplified approach to calculate atomic partition functions in plasmas
D'Ammando, Giuliano; Colonna, Gianpiero
2013-03-15
A simplified method to calculate the electronic partition functions and the corresponding thermodynamic properties of atomic species is presented and applied to C(I) up to C(VI) ions. The method consists in reducing the complex structure of an atom to three lumped levels. The ground level of the lumped model describes the ground term of the real atom, while the second lumped level represents the low lying states and the last one groups all the other atomic levels. It is also shown that for the purpose of thermodynamic function calculation, the energy and the statistical weight of the upper lumped level, describing high-lying excited atomic states, can be satisfactorily approximated by an analytic hydrogenlike formula. The results of the simplified method are in good agreement with those obtained by direct summation over a complete set (i.e., including all possible terms and configurations below a given cutoff energy) of atomic energy levels. The method can be generalized to include more lumped levels in order to improve the accuracy.
Programmable calculator software for computation of the plasma binding of ligands.
Conner, D P; Rocci, M L; Larijani, G E
1986-01-01
The computation of the extent of plasma binding of a ligand to plasma constituents using radiolabeled ligand and equilibrium dialysis is complex and tedious. A computer program for the HP-41C Handheld Computer Series (Hewlett-Packard) was developed to perform these calculations. The first segment of the program constructs a standard curve for quench correction of post-dialysis plasma and buffer samples, using either external standard ratio (ESR) or sample channels ratio (SCR) techniques. The remainder of the program uses the counts per minute, SCR or ESR, and post-dialysis volume of paired plasma and buffer samples generated from the dialysis procedure to compute the extent of binding after correction for background radiation, counting efficiency, and intradialytic shifts of fluid between plasma and buffer compartments during dialysis. This program greatly simplifies the analysis of equilibrium dialysis data and has been employed in the analysis of dexamethasone binding in normal and uremic sera. PMID:3754197
Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment
Bhattacharyya, S.; Saha, J. K.; Mukherjee, T. K.
2015-04-01
In this work, the controversy between the interpretations of recent measurements on dense aluminum plasma created with the Linac coherent light source (LCLS) x-ray free electron laser (FEL) and the Orion laser has been addressed. In both kinds of experiments, heliumlike and hydrogenlike spectral lines are used for plasma diagnostics. However, there exist no precise theoretical calculations for He-like ions within a dense plasma environment. The strong need for an accurate theoretical estimate for spectral properties of He-like ions in a strongly coupled plasma environment leads us to perform ab initio calculations in the framework of the Rayleigh-Ritz variation principle in Hylleraas coordinates where an ion-sphere potential is used. An approach to resolve the long-drawn problem of numerical instability for evaluating two-electron integrals with an extended basis inside a finite domain is presented here. The present values of electron densities corresponding to the disappearance of different spectral lines obtained within the framework of an ion-sphere potential show excellent agreement with Orion laser experiments in Al plasma and with recent theories. Moreover, this method is extended to predict the critical plasma densities at which the spectral lines of H-like and He-like carbon and argon ions disappear. Incidental degeneracy and level-crossing phenomena are being reported for two-electron ions embedded in strongly coupled plasma. Thermodynamic pressure experienced by the ions in their respective ground states inside the ion spheres is also reported.
A 3-D Theoretical Model for Calculating Plasma Effects in Germanium Detectors
NASA Astrophysics Data System (ADS)
Wei, Wenzhao; Liu, Jing; Mei, Dongming; Cubed Collaboration
2015-04-01
In the detection of WIMP-induced nuclear recoil with Ge detectors, the main background source is the electron recoil produced by natural radioactivity. The capability of discriminating nuclear recoil (n) from electron recoil (γ) is crucial to WIMP searches. Digital pulse shape analysis is an encouraging approach to the discrimination of nuclear recoil from electron recoil since nucleus is much heavier than electron and heavier particle generates ionization more densely along its path, which forms a plasma-like cloud of charge that shields the interior from the influence of the electric field. The time needed for total disintegration of this plasma region is called plasma time. The plasma time depends on the initial density and radius of the plasma-like cloud, diffusion constant for charge carriers, and the strength of electric field. In this work, we developed a 3-D theoretical model for calculating the plasma time in Ge detectors. Using this model, we calculated the plasma time for both nuclear recoils and electron recoils to study the possibility for Ge detectors to realize n/ γ discrimination and improve detector sensitivity in detecting low-mass WIMPs. This work is supported by NSF in part by the NSF PHY-0758120, DOE Grant DE-FG02-10ER46709, and the State of South Dakota.
Viscosity calculated in simulations of strongly coupled dusty plasmas with gas friction
Feng Yan; Goree, J.; Liu Bin
2011-05-15
A two-dimensional strongly coupled dusty plasma is modeled using Langevin and frictionless molecular dynamical simulations. The static viscosity {eta} and the wave-number-dependent viscosity {eta}(k) are calculated from the microscopic shear in the random motion of particles. A recently developed method of calculating the wave-number-dependent viscosity {eta}(k) is validated by comparing the results of {eta}(k) from the two simulations. It is also verified that the Green-Kubo relation can still yield an accurate measure of the static viscosity {eta} in the presence of a modest level of friction as in dusty plasma experiments.
Quantum-Mechanical Calculation of Ionization-Potential Lowering in Dense Plasmas
NASA Astrophysics Data System (ADS)
Son, Sang-Kil; Thiele, Robert; Jurek, Zoltan; Ziaja, Beata; Santra, Robin
2014-07-01
The charged environment within a dense plasma leads to the phenomenon of ionization-potential depression (IPD) for ions embedded in the plasma. Accurate predictions of the IPD effect are of crucial importance for modeling atomic processes occurring within dense plasmas. Several theoretical models have been developed to describe the IPD effect, with frequently discrepant predictions. Only recently, first experiments on IPD in Al plasma have been performed with an x-ray free-electron laser, where their results were found to be in disagreement with the widely used IPD model by Stewart and Pyatt. Another experiment on Al, at the Orion laser, showed disagreement with the model by Ecker and Kröll. This controversy shows a strong need for a rigorous and consistent theoretical approach to calculate the IPD effect. Here, we propose such an approach: a two-step Hartree-Fock-Slater model. With this parameter-free model, we can accurately and efficiently describe the experimental Al data and validate the accuracy of standard IPD models. Our model can be a useful tool for calculating atomic properties within dense plasmas with wide-ranging applications to studies on warm dense matter, shock experiments, planetary science, inertial confinement fusion, and nonequilibrium plasmas created with x-ray free-electron lasers.
Improved Frequency Fluctuation Model for Spectral Line Shape Calculations in Fusion Plasmas
NASA Astrophysics Data System (ADS)
Ferri, S.; Calisti, A.; Mossé, C.; Talin, B.; Lisitsa, V.
2010-10-01
A very fast method to calculate spectral line shapes emitted by plasmas accounting for charge particle dynamics and effects of an external magnetic field is proposed. This method relies on a new formulation of the Frequency Fluctuation Model (FFM), which yields to an expression of the dynamic line profile as a functional of the static distribution function of frequencies. This highly efficient formalism, not limited to hydrogen-like systems, allows to calculate pure Stark and Stark-Zeeman line shapes for a wide range of density, temperature and magnetic field values, which is of importance in plasma physics and astrophysics. Various applications of this method are presented for conditions related to fusion plasmas.
Preface to Special Topic: Advances in Radio Frequency Physics in Fusion Plasmas
Tuccillo, Angelo A.; Ceccuzzi, Silvio; Phillips, Cynthia K.
2014-06-15
It has long been recognized that auxiliary plasma heating will be required to achieve the high temperature, high density conditions within a magnetically confined plasma in which a fusion “burn” may be sustained by copious fusion reactions. Consequently, the application of radio and microwave frequency electromagnetic waves to magnetically confined plasma, commonly referred to as RF, has been a major part of the program almost since its inception in the 1950s. These RF waves provide heating, current drive, plasma profile control, and Magnetohydrodynamics (MHD) stabilization. Fusion experiments employ electromagnetic radiation in a wide range of frequencies, from tens of MHz to hundreds of GHz. The fusion devices containing the plasma are typically tori, axisymmetric or non, in which the equilibrium magnetic fields are composed of a strong toroidal magnetic field generated by external coils, and a poloidal field created, at least in the symmetric configurations, by currents flowing in the plasma. The waves are excited in the peripheral regions of the plasma, by specially designed launching structures, and subsequently propagate into the core regions, where resonant wave-plasma interactions produce localized heating or other modification of the local equilibrium profiles. Experimental studies coupled with the development of theoretical models and advanced simulation codes over the past 40+ years have led to an unprecedented understanding of the physics of RF heating and current drive in the core of magnetic fusion devices. Nevertheless, there are serious gaps in our knowledge base that continue to have a negative impact on the success of ongoing experiments and that must be resolved as the program progresses to the next generation devices and ultimately to “demo” and “fusion power plant.” A serious gap, at least in the ion cyclotron (IC) range of frequencies and partially in the lower hybrid frequency ranges, is the difficulty in coupling large amount of
Preface to Special Topic: Advances in Radio Frequency Physics in Fusion Plasmas
NASA Astrophysics Data System (ADS)
Tuccillo, Angelo A.; Phillips, Cynthia K.; Ceccuzzi, Silvio
2014-06-01
It has long been recognized that auxiliary plasma heating will be required to achieve the high temperature, high density conditions within a magnetically confined plasma in which a fusion "burn" may be sustained by copious fusion reactions. Consequently, the application of radio and microwave frequency electromagnetic waves to magnetically confined plasma, commonly referred to as RF, has been a major part of the program almost since its inception in the 1950s. These RF waves provide heating, current drive, plasma profile control, and Magnetohydrodynamics (MHD) stabilization. Fusion experiments employ electromagnetic radiation in a wide range of frequencies, from tens of MHz to hundreds of GHz. The fusion devices containing the plasma are typically tori, axisymmetric or non, in which the equilibrium magnetic fields are composed of a strong toroidal magnetic field generated by external coils, and a poloidal field created, at least in the symmetric configurations, by currents flowing in the plasma. The waves are excited in the peripheral regions of the plasma, by specially designed launching structures, and subsequently propagate into the core regions, where resonant wave-plasma interactions produce localized heating or other modification of the local equilibrium profiles. Experimental studies coupled with the development of theoretical models and advanced simulation codes over the past 40+ years have led to an unprecedented understanding of the physics of RF heating and current drive in the core of magnetic fusion devices. Nevertheless, there are serious gaps in our knowledge base that continue to have a negative impact on the success of ongoing experiments and that must be resolved as the program progresses to the next generation devices and ultimately to "demo" and "fusion power plant." A serious gap, at least in the ion cyclotron (IC) range of frequencies and partially in the lower hybrid frequency ranges, is the difficulty in coupling large amount of power to the
A calculational approach to electron impact excitation of ions in hot solar plasmas
NASA Technical Reports Server (NTRS)
Temkin, A.
1974-01-01
The cross section requirements are presented for studying UV and X-ray emission spectra associated with active and flare-produced plasmas in the sun's corona. The general approach to the calculation of the distorted wave approximation problem is also given.
NASA Astrophysics Data System (ADS)
Evstatiev, Evstati; Svidzinski, Vladimir; Spencer, Andy; Galkin, Sergei
2014-10-01
Full wave 3-D modeling of RF fields in hot magnetized nonuniform plasma requires calculation of nonlocal conductivity kernel describing the dielectric response of such plasma to the RF field. In many cases, the conductivity kernel is a localized function near the test point which significantly simplifies numerical solution of the full wave 3-D problem. Preliminary results of feasibility analysis of numerical calculation of the conductivity kernel in a 3-D hot nonuniform magnetized plasma in the electron cyclotron frequency range will be reported. This case is relevant to modeling of ECRH in ITER. The kernel is calculated by integrating the linearized Vlasov equation along the unperturbed particle's orbits. Particle's orbits in the nonuniform equilibrium magnetic field are calculated numerically by one of the Runge-Kutta methods. RF electric field is interpolated on a specified grid on which the conductivity kernel is discretized. The resulting integrals in the particle's initial velocity and time are then calculated numerically. Different optimization approaches of the integration are tested in this feasibility analysis. Work is supported by the U.S. DOE SBIR program.
Plasma induced sputtering yield and backscattering for ITER-relevant materials as calculated by TRIM
NASA Astrophysics Data System (ADS)
Kumar, P.; Ahmad, A.; Carrère, M.
2015-07-01
In this paper, we report an analytical model to estimate the variation of the yield (and hence the pressure) from sputtering, elastic collisions, and backscattering on a surface exposed to International Thermonuclear Experimental Reactor-relevant plasmas. To study the yield and the pressure exerted on the surfaces of carbon (C), silicon (Si) and tungsten (W) due to plasma exposure, the irradiation of H, Ar and Xe ions at normal incidence was considered. Transport and range of ions in matter simulations were done to calculate the backscattering/sputtering yields and the energies on the surfaces. The calculations are significant for the optimization of material facing the plasma in future fusion reactors where erosion and long term operation are key issues. The results show that yield increases with the increase of ion energy. The carbon surface is the least affected to exposure of the plasma. In the chosen ion energy range (0-1 keV), the simulations/calculations (for Ar ion incident on Si and W) are in good agreement with published experimental results.
Calculated non-linear magnetic field penetration of plasma opening switches
Mason, R.J.; Jones, M.E.; Wilson, D.C.; Bergman, C.; Thiem, K. ); Grossmann, J.M.; Ottinger, P.F. )
1990-06-15
We examine magnetic field penetration in the Plasma Opening Switch, exploring, in particular, advective field penetration arising in conjunction with radial density gradients across the cathode anode gap. Our calculations have been completed with the implicit multi-fluid, ANTHEM code. We show favored penetration along a radial density jump, unstable plain wave penetration for a 1/(y {minus} y{sub {alpha}+{epsilon}}) density dependence (with y measured from cathode to anode at Y{sub {alpha}}) in planar switches, and the penetration of finger-like magnetic field perturbations, when the fill plasmas bears initial sinusoidal disturbances on its generator interface. 7 refs., 4 figs.
Calculation of optical properties for hot plasmas using a screened hydrogenic model
NASA Astrophysics Data System (ADS)
Rubiano, J. G.; Rodríguez, R.; Florido, R.; Mendoza, M. A.; Gil, J. M.; Martel, P.; Mínguez, E.
2006-06-01
In work a hydrogenic versions of the code ATOM3R-OP is presented. This flexible code has been developed to obtain optical properties for plasmas in a wide range of densities and temperatures named and the Hydrogenic versions is intended to couple with hydrodynamic codes. The code is structured in three modules devoted to the calculation of the atomic magnitudes, the ionic abundances and the optical properties, respectively, which are briefly described. Finally, bound-bound opacities and emissivities of Carbon plasma computed with this model are compared with more sophisticated self-consistent codes.
A method for calculating plasma rotation velocity due to internal and external sources
Taguchi, M.
2011-10-15
A method for calculating the plasma rotation velocity caused by the effect of fluctuations due to instabilities and/or by externally imposed sources is presented for multiple ion species plasmas in a general toroidal magnetic field. The rotation velocity is shown to be obtained by solving generalized Spitzer equations, accompanied with the drift kinetic equations employing the pitch-angle-scattering and Krook collision terms. This method reduces to the moment equation approach in the conventional neoclassical transport theory when the source term can be approximated by a momentum source.
Calculation of sheath and wake structure about a pillbox-shaped spacecraft in a flowing plasma
NASA Technical Reports Server (NTRS)
Parker, L. W.
1977-01-01
A computer program was used for studies of the disturbed zones around bodies in flowing plasmas, particularly spacecraft and their associated sheaths and wakes. The program solved a coupled Poisson-Vlasov system of nonlinear partial differential integral equations to obtain distributions of electric potential and ion and electron density about a finite length cylinder in a plasma flow at arbitrary ion Mach numbers. The approach was applicable to a larger range of parameters than other available approaches. In sample calculations, bodies up to 100 Debye lengths in radius were treated, that is, larger than any previously treated realistically. Applications were made to in-situ satellite experiments.
Transport timescale calculations of sawteeth and helical structures in non-circular tokamak plasmas
NASA Astrophysics Data System (ADS)
Jardin, Stephen; Ferraro, Nate; Breslau, Josh; Chen, Jin
2012-10-01
We present results of using the implicit 3D MHD code M3D-C^1 [1,2] to perform 3D nonlinear magnetohydrodynamics calculations of the internal dynamics of a shaped cross-section tokamak plasma that span the timescales associated with ideal and resistive stability as well as parallel and perpendicular transport. We specify the transport coefficients and apply a ``current controller'' that adjusts the boundary loop-voltage to keep the total plasma current fixed. The 3D 2-fluid plasma model advances the magnetic field, velocities, electron and ion temperatures, and plasma density. We find that the plasma either reaches a stationary quasi-helical state in which the central safety factor is approximately unity, or it periodically undergoes either simple or compound sawtooth oscillations [3] with a period that approaches a constant value. By comparing a dee-shaped cross section with an elliptical shaped cross section, it is shown that the plasma shape has a large effect on determining the sawtooth behavior and the associated mode activity. Application to ITER shaped tokamak plasmas predict the magnitude of the 3D boundary deformation as a result of a stationary quasi-helical state forming in the interior. [4pt] [1] J. Breslau, N. Ferraro, S.C. Jardin, Physics of Plasmas 16 092503 (2009) [0pt] [2] S. C. Jardin, N. Ferraro, J. Breslau, J. Chen, Computational Science and Discovery 5 014002 (2012) [0pt] [3] X. von Goeler, W. Stodiek, and N. Sauthoff, Phys. Rev. Lett. 33, 1201 (1974)
Plasma turbulence calculations on the Intel iPSC/860 (rx) hypercube
Lynch, V.E. . Computing and Telecommunications Div.); Carreras, B.A.; Drake, J.B.; Leboeuf, J.N. ); Ruiter, J.R. )
1990-01-01
One approach to improving the real-time efficiency of plasma turbulence calculations is to use a parallel algorithm. A serial algorithm used for plasma turbulence calculations was modified to allocate a radial region in each node. In this way, convolutions at a fixed radius are performed in parallel, and communication is limited to boundary values for each radial region. For a semi-implicity numerical scheme (tridiagonal matrix solver), there is a factor of 3 improvement in efficiency with the Intel iPSC/860 machine using 64 processors over a single-processor Cray-II. For block-tridiagonal matrix cases (fully implicit code), a second parallelization takes place. The Fourier components are distributed in nodes. In each node, the block-tridiagonal matrix is inverted for each of allocated Fourier components. The algorithm for this second case has not yet been optimized. 10 refs., 4 figs.
ERIC Educational Resources Information Center
Luna, Pat
Designed for middle school students, this award winning, six-day teaching unit helped students learn about the concepts of specialization, interdependence, efficiency, and profit. At the onset of the lesson the students were already familiar with the concepts of scarcity, goods, services, profits, supply, demand, and opportunity costs. The unit's…
Calculation of a plasma HgDyI{sub 3} transport coefficients
Hajji, S.; HadjSalah, S.; Benhalima, A.; Charrada, K.; Zissis, G.
2015-05-15
This work is devoted to the calculation of the chemical composition and transport coefficients of HgDyI{sub 3} plasmas in thermal equilibrium. These calculations are performed for pressures equal to 2MP and for temperatures varying from 1000 to 10 000 K. The thermal and electrical conductivity as well as viscosity have been computed as a function of temperature at different atomic ratios. The computational method proposed by Devoto from the classical formalism described by Hirschfelder et al. [Molecular Theory of Gases and Liquids (John Wiley and Sons, New York, 1954)] is used.
Calculation and observation of thermal electrostatic noise in solar wind plasma
NASA Technical Reports Server (NTRS)
Kellogg, P. J.
1981-01-01
Calculations, both approximate algebraic and numerical, have been carried out for the noise due to electrostatic waves incident on a dipole antenna. The noise is calculated both for a thermal equilibrium plasma, and one having several components at different temperatures. The results are compared with measurements from the IMP-6 satellite. In various frequency ranges, the noise power is dominated by Langmuir oscillations, by electron acoustic waves and by ion acoustic waves. The measurements are consistent with all of these, although the ion waves are not definitely observed, due to interference from shot noise.
Multi-Center Electronic Structure Calculations for Plasma Equation of State
Wilson, B G; Johnson, D D; Alam, A
2010-12-14
We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.
NASA Astrophysics Data System (ADS)
Zhang, X. N.; Li, H. P.; Murphy, A. B.; Xia, W. D.
2015-06-01
Two main methods have been used to calculate the transport properties of two-temperature (2-T) plasmas in local chemical equilibrium: the method of Devoto (method B), in which coupling between electrons and heavy species is neglected, and the method of Rat et al (method C), in which coupling is included at the cost of a considerable increase in complexity. A new method (method A) has recently been developed, based on the modified Chapman-Enskog solution of the species Boltzmann equations. This method retains coupling between electrons and heavy species by including the electron-heavy-species collision term in the heavy-species Boltzmann equation. In this paper, the properties of 2-T argon plasmas calculated using the three methods are compared. The viscosity, electrical conductivity and translational thermal conductivity obtained using all three methods are very similar. method B does not allow a complete set of species diffusion coefficient to be obtained. It is shown that such a set can be calculated using method A without any significant loss of accuracy. Finally, it is important to note that, by using the physical fact that the mass of heavy particles is much larger than that of electrons (i.e. me << mh), the complexity of calculations using method A is not increased compared with method B; that is to say, the calculation procedure is much simpler than with method C.
Study of plasma equilibrium in toroidal fusion devices using mesh-free numerical calculation method
NASA Astrophysics Data System (ADS)
Rasouli, C.; Abbasi Davani, F.; Rokrok, B.
2016-08-01
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 has 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.
Calculated radiative power losses from mid- and high-Z impurities in Tokamak plasmas
NASA Astrophysics Data System (ADS)
Fournier, Kevin B.; May, M. J.; Pacella, D.; Gregory, B. C.; Rice, J. E.; Terry, J. L.; Finkenthal, M.; Goldstein, W. H.
1998-09-01
This paper summarizes recent calculations of the radiative cooling coefficient for molybdenum (Z=42), krypton (Z=36) and argon (Z=18). The radiative processes considered are collisional-radiative line emission, dielectronic recombination line emission, and radiative recombination and bremsstrahlung continuum emission. Collisional-radiative line emission dominates the power loss channels for a given impurity at all but the highest plasma electron temperatures. The atomic data for the line emission are computed ab initio with the HULLAC atomic physics suite of codes. Relativistic, ab initio atomic physics data are used to compute ionization and recombination rate coefficients; the resulting charge state distribution and recombination rates are used to estimate the radiative power from recombination processes. The calculations in the present work are benchmarked against absolute measurements of ion brightness profiles in the Frascati Tokamak Upgrade plasma. Integrated measurements from tokamak plasmas such as bolometry are then simulated. The atomic physics data used to predict the emissivity of individual ions is validated; the calculated cooling coefficients agree well with bolometric measurements.
NASA Astrophysics Data System (ADS)
Thomas, Johannes; Kostyukov, Igor Yu.; Pronold, Jari; Golovanov, Anton; Pukhov, Alexander
2016-05-01
We introduce a complete semi-analytical model for a cavitated electron wake driven by an electron beam in a radially inhomogeneous plasma. The electron response to the driver, dynamics of electrons in a thin sheath surrounding the cavity, as well as accelerating and focusing fields inside the cavity are calculated in the quasistatic approximation. Our theory holds for arbitrary radial density profiles and reduces to known models in the limit of a homogeneous plasma. A free-propagating blow-out in an evacuated channel experiences longitudinal squeezing, qualitatively the same as observed in particle-in-cell simulations for the laser pulse-driven case [Pukhov et al., Phys. Rev. Lett. 113, 245003 (2014)]. Our model also permits qualitative interpretation of the earlier observed cancellation of the focusing gradient in the cavity [Pukhov et al., Phys. Rev. Lett. 113, 245003 (2014)]. In this work, we show the underlying mechanism that causes the radial fields in the vacuum part of a channel to become defocussing.
Yamamoto, K.; Mizuno, Y.; Hibino, S.; Inuzuka, H.; Cao, Y.; Liu, Y.; Yazawa, K.
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{sup 4} particles, GRAPE-6 can perform the whole operation 1000 times faster than by using a Pentium 4 1.6 GHz processor.
Liu, Li; Xiao, Ping-ping
2016-02-01
Temperature is one of the most important parameters in studying of laser-induced plasma characteristics. To reduce the impact of continuous background on the calculation of temperatures using Boltzmann plots, the wavelet transform was used to decompose the spectrums, and the low-frequency signals represented the spectral baseline were deducted by using soft-threshold method. Selecting the appropriate wavelet decomposition level L and threshold coefficient a can increase the linear regression coefficient R2 of Boltzmann plots, and the calculation accuracy of plasma temperature was improved. The LIBS spectra of low alloy steel sample region from 417 to 445 nm were decomposed by using db4 wavelet, and then baseline subtraction and signal reconstruction were carried out, respectively. Twelve Fe atomic lines were chosen to establish Boltzmann plots, and the temperatures were calculated from the slope of the fitted lines in the plots. The value L and a were optimized according R², the results showed that the 8-layer db4 wavelet decomposition can gain the high R², while the value of a associated with the delay time td, e. g. , the optimum a corresponding to maximum values of R² is 0.3 when td ≤ 4.0 µs, and then decrease with the increasing of td, and reduced to 0 when td ≥ 6. 0 µs. The interference due to baseline on the spectral characteristic lines gradually reduced with the increasing of td, and therefore a decreased with td increase. After the baseline was deducted, the temperature calculated by Boltzmann plot decrease of about 2 000 to 3 000 K. The temperature gradually decreased with the increasing of the td, and the temperature fluctuation is reduced after baseline subtraction, these results are consistent with the physical process of plasma expansion. PMID:27209766
NASA Astrophysics Data System (ADS)
Walsh, Daniel K.; Dubin, Daniel H. E.
2015-11-01
This poster presents theory and numerical calculations of electrostatic Bernstein modes in an inhomogeneous cylindrical plasma column. These modes rely on FLR effects to propagate radially across the column until they are reflected when their frequency matches the local upper hybrid frequency, setting up an internal normal mode on the column, and also mode-coupling to the electrostatic surface cyclotron wave (which allows the normal mode to be excited and observed using external electrodes). Numerical results predicting the mode spectra, using a novel linear Vlasov code on a cylindrical grid, will be presented and compared to an analytic WKB theory. A previous version of the theory expanded the plasma response in powers of 1/B, approximating the local upper hybrid frequency, and consequently its frequency predictions are shifted with respect to the numerical results. A new version of the WKB theory uses the exact cold fluid plasma response and does a better job of reproducing the numerical frequency spectrum. The eventual goal is to compare the theory to recent experiments that have observed these waves in pure electron and pure ion plasmas. Supported by National Science Foundation Grant PHY-1414570.
Core Physics and Kinetics Calculations for the Fissioning Plasma Core Reactor
NASA Technical Reports Server (NTRS)
Butler, C.; Albright, D.
2007-01-01
Highly efficient, compact nuclear reactors would provide high specific impulse spacecraft propulsion. This analysis and numerical simulation effort has focused on the technical feasibility issues related to the nuclear design characteristics of a novel reactor design. The Fissioning Plasma Core Reactor (FPCR) is a shockwave-driven gaseous-core nuclear reactor, which uses Magneto Hydrodynamic effects to generate electric power to be used for propulsion. The nuclear design of the system depends on two major calculations: core physics calculations and kinetics calculations. Presently, core physics calculations have concentrated on the use of the MCNP4C code. However, initial results from other codes such as COMBINE/VENTURE and SCALE4a. are also shown. Several significant modifications were made to the ISR-developed QCALC1 kinetics analysis code. These modifications include testing the state of the core materials, an improvement to the calculation of the material properties of the core, the addition of an adiabatic core temperature model and improvement of the first order reactivity correction model. The accuracy of these modifications has been verified, and the accuracy of the point-core kinetics model used by the QCALC1 code has also been validated. Previously calculated kinetics results for the FPCR were described in the ISR report, "QCALC1: A code for FPCR Kinetics Model Feasibility Analysis" dated June 1, 2002.
Zheng, Kai; Li, Huan; Yang, Li-Jun; Gu, Xiao-Yan; Gao, Ying
2013-04-01
The plasma radiation of laser-double wire hybrid welding was collected by using fiber spectrometer, the coupling mechanism of arc with laser was studied through high-speed photography during welding process, and the temperature of hybrid plasma was calculated by using the method of Boltzmann plot. The results indicated that with laser hybrid, luminance was enhanced; radiation intensity became stronger; arc was attracted to the laser point; cross section contracted and arc was more stable. The laser power, welding current and arc-arc distance are important factors that have great influence on electron temperature. Increase in the laser power, amplification of welding current and reduction of arc-arc distance can all result in the rise of temperature. PMID:23841392
Special methods for aerodynamic-moment calculations from parachute FSI modeling
NASA Astrophysics Data System (ADS)
Takizawa, Kenji; Tezduyar, Tayfun E.; Boswell, Cody; Tsutsui, Yuki; Montel, Kenneth
2015-06-01
The space-time fluid-structure interaction (STFSI) methods for 3D parachute modeling are now at a level where they can bring reliable, practical analysis to some of the most complex parachute systems, such as spacecraft parachutes. The methods include the Deforming-Spatial-Domain/Stabilized ST method as the core computational technology, and a good number of special FSI methods targeting parachutes. Evaluating the stability characteristics of a parachute based on how the aerodynamic moment varies as a function of the angle of attack is one of the practical analyses that reliable parachute FSI modeling can deliver. We describe the special FSI methods we developed for this specific purpose and present the aerodynamic-moment data obtained from FSI modeling of NASA Orion spacecraft parachutes and Japan Aerospace Exploration Agency (JAXA) subscale parachutes.
NASA Astrophysics Data System (ADS)
Grach, Savely; Bareev, Denis; Gavrilenko, Vladimir; Sergeev, Evgeny
Damping rates of plasma waves with ω ˜ ωuh (ω is the plasma wave frequency, ωuh is the upper hybrid frequency) were calculated for frequencies close to and distant from the double resonance where ωuh ˜ nωce (ωce is the electron cyclotron frequency, n=4,5 are the gyroharmonic num-bers). The calculations were performed numerically on the base of full plasma wave dispersion relation not restricted by both the 'long wave limit' and 'short wave limit', i.e. a fulfillment of the inequalities |∆| |k |vTe and |∆| |k |vTe was not required. Here ∆ = ω - nωce , vTe = (Te /me )1/2 is the electron thermal velocity and k is the projection of the wave vector onto the magnetic field direction. It is shown that the plasma wave damping rates do not differ noticeably from ones calculated under the long wave and short wave limits. The results obtained are compared with the data of the relaxation of the stimulated electromagnetic emission (SEE) after the pump wave turn off, which demonstrate an essential decrease of the relaxation time near 4th electron gyroharmonic, so far as the SEE relaxation is attributed to the damping of plasma waves responsible for the SEE generation. The comparison allows to determine characteristics of plasma waves mostly contributing to the SEE generation, such as wave numbers and the angles between the wave vectors and geomagnetic field, and the altitude region of the SEE source. The dependence of the decay rate on ∆ can be applied also to interpretation of the SEE spectral shape at different pump frequencies near gyroharmonics. The work is supported by RFBR grants 10-02-00642, 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia".
Bar-Shalon, A.; Oreg, J. . Nuclear Research Center-Negev); Goldstein, W.H. )
1991-01-11
Recent improvements in the Super Transition Array (STA) method for calculating Bound-Bound (BB) and Bound-Free (BF) emission and absorption spectra for LTE plasma are described and illustrated. The method accounts for all possible BB and BF radiative transitions in the plasma. Full detailed first order quantum relativistic treatment is used for calculating transition energies and probabilities. The enormous number of configurations are divided into sets of superconfigurations comprised of a collection of energetically grouped configurations. The contribution of the transition array between two superconfigurations to a specific one-electron transition is then represented by a Gaussian whose moments are calculated accurately using a technique that bypasses the necessity of direct summation over all the levels involved. The calculation of these moments involves the populations of the configurations given by their statistical weights and the Boltzmann factor. For each configuration within the super configuration we use zeroeth order energies in the Boltzmann factor corrected by a super configuration averaged first order term. The structure of the spectrum is increasingly revealed by splitting each STA into a number of smaller STAs. When the spectrum converges it describes the detailed UTA' structure, where each configuration-to-configuration array is represented by a separate Gaussian with first order energy in the Boltzmann factor. Convergence is reached with only a few thousand STAs, at most, which makes the calculations practical. It should be pointed out that in this treatment the STA moments are obtained by summing over all level-to-level transitions, rather than configuration-to-configuration average transitions. 4 refs., 9 figs.
Collisional-radiative calculations of He line emission in low-temperature plasmas
Ballance, C. P.; Griffin, D. C.; Loch, S. D.; Boivin, R. F.; Pindzola, M. S.
2006-07-15
We present spectral modeling results for neutral helium. Our underlying atomic data contains radiative transition rates that are generated from atomic structure calculations and electron-impact excitation rates, that are determined from both the standard R-matrix method and the R-matrix with pseudostates (RMPS) method. In this paper, we focus on transitions of particular importance to diagnostic line ratios. For example, our calculated rate coefficient for the electron-impact transition 1s3s {sup 1}S{yields}1s3p {sup 1}P, which has a pronounced effect on the 728.1 nm diagnostic spectral line, is found to be in good agreement with previous experimental measurements. We also consider transitions from the 1s{sup 2} {sup 1}S ground and 1s2s {sup 3}S terms to terms of the n=4 shell. They are found to be affected significantly by coupling of the bound states to the target continuum (continuum coupling), which is included in our RMPS calculation, but not in our standard R-matrix calculation. We perform collisional-radiative calculations to determine spectral line intensity ratios for three ratios of particular interest, namely the 504.8 nm/471.3 nm, 492.2 nm/471.3 nm, and 492.2 nm/504.8 nm line ratios. Comparing our results determined from the RMPS excitation rates with those from the standard R-matrix excitation rates, we find that continuum coupling affects the rate coefficients significantly, leading to different values for all three line ratios. We also compare our modeling results with spectral measurements taken recently on the Auburn Helicon plasma device, finding that the ground and metastable populations are not in equilibrium, and that the experimental measurements are more consistent with the 1s2s {sup 3}S metastable term populations being short lived in the plasma.
MCDHF calculations and study of plasma parameters for Li-like ions
NASA Astrophysics Data System (ADS)
Khatri, Indu; Goyal, Arun; Aggarwal, Sunny; Singh, A. K.; Man Mohan
2016-06-01
Extensive configuration interaction calculations for several Li-like ions (Z=32, 36, 42, 46, 50, 54 and 56) are performed using the code GRASP2K based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Breit interaction and leading quantum electrodynamical (QED) effects are also included by applying active-space techniques to enlarge the configuration set. Results for fine-structure energy levels for 1s22p, 1s23s, 1s23p and 1s23d configurations with relative to ground states 1s22s are presented. The wavelengths, transition rates and oscillator strengths for the 1s22s 2S1/2-1s22p 1/2,3/2,0 2P, 1s22p 1/2,3/2,0,2P - -1s23s 2S1/2, 1s22p calculated results are in good agreement with previous theoretical results and compiled values of the National Institute for Standards and Technology (NIST). We have also provided the line intensity ratios and plasma parameters for optically thin plasma. Our calculated data may be useful for experimentalists in identifying the fine-structure levels, for plasma modeling, astrophysical research applications.
Hamiltonian guiding center drift orbit calculation for toroidal plasmas of arbitrary cross section
White, R.B.; Chance, M.S.
1984-02-01
A Hamiltonian guiding center drift orbit formalism is developed which permits the efficient calculation of particle trajectories in toroidal devices of arbitrary cross section with arbitrary plasma ..beta... The magnetic field is assumed to be a small perturbation from a zero order toroidal equilibrium field possessing either axial or helical symmetry. The equilibrium field can be modelled analytically or obtained numerically from equilibrium codes. A numerical code based on the formalism is used to study particle orbits in circular and bean-shaped tokamak configurations.
Numerical methods for the calculation of special functions of wave catastrophes
NASA Astrophysics Data System (ADS)
Ipatov, E. B.; Lukin, D. S.; Palkin, E. A.
1985-02-01
The paper investigates the properties of special functions which are used for the asymptotic description of the structure of wave fields near various types of focusings. These functions are realized in software packages for the BESM-6 computer using FORTRAN. The canonical equations and basic properties of these functions are examined along with the development of numerical algorithms for their computation. These functions may be applied in the study of various types of wave problems, including: (1) radio wave propagation in the ionosphere and ionospheric waveguide channels; (2) the fine structure of sound fields in an acoustic duct; and (3) the focusing of laser radiation reflected from a rough surface.
NASA Astrophysics Data System (ADS)
Anoshko, I. A.; Ermachenko, V. S.
2006-05-01
The velocity of a plasma jet in the nozzle exit section and the pressure in the discharge zone of a coaxial-electrode Hall accelerator have been calculated on the basis of the experimentally measured enthalpy, temperature, and electron concentration near the indicated section within the framework of a model of the magnetic hydrodynamics of a plasma flow.
Beta electron fluxes inside a magnetic plasma cavern: Calculation and comparison with experiment
NASA Astrophysics Data System (ADS)
Stupitskii, E. L.; Smirnov, E. V.; Kulikova, N. A.
2010-12-01
We study the possibility of electrostatic blanking of beta electrons in the expanding spherical blob of a radioactive plasma in a rarefied ionosphere. From numerical studies on the dynamics of beta electrons departing a cavern, we obtain the form of a function that determines the portion of departing electrons and calculate the flux density of beta electrons inside the cavern in relation to the Starfish Prime nuclear blast. We show that the flux density of electrons in geomagnetic flux tubes and inside the cavern depend on a correct allowance for the quantity of beta electrons returning to the cavern. On the basis of a physical analysis, we determine the approximate criterion for the return of electrons from a geomagnetic flux tube to the cavern. We compare calculation results in terms of the flux density of beta electrons inside the cavern with the recently published experimental results from operation Starfish Prime.
Kokkoris, George; Boudouvis, Andreas G.; Gogolides, Evangelos
2006-11-15
An integrated framework for the neutral flux calculation inside trenches and holes during plasma etching is described, and a comparison between the two types of structure in a number of applications is presented. First, a detailed and functional set of equations for the neutral and ion flux calculations inside long trenches and holes with cylindrical symmetry is explicitly formulated. This set is based on early works [T. S. Cale and G. B. Raupp, J. Vac. Sci. Technol. B 8, 1242 (1990); V. K. Singh et al., J. Vac. Sci. Technol. B 10, 1091 (1992)], and includes new equations for the case of holes with cylindrical symmetry. Second, a method for the solution of the respective numerical task, i.e., one or a set of linear or nonlinear integral equations, is described. This method includes a coupling algorithm with a surface chemistry model and resolves the singularity problem of the integral equations. Third, the fluxes inside trenches and holes are compared. The flux from reemission is the major portion of the local flux at the bottom of both types of structure. The framework is applied in SiO{sub 2} etching by fluorocarbon plasmas to predict the increased intensity of reactive ion etching lag in SiO{sub 2} holes compared to trenches. It is also applied in deep Si etching: By calculating the flux of F atoms at the bottom of very high aspect ratio (up to 150) Si trenches and holes during the gas chopping process, the aspect ratio at which the flux of F atoms is eliminated and etching practically stops is estimated.
NASA Astrophysics Data System (ADS)
Marchand, R.; Purschke, D.; Samson, J.
2013-03-01
Understanding the physics of interaction between satellites and the space environment is essential in planning and exploiting space missions. Several computer models have been developed over the years to study this interaction. In all cases, simulations are carried out in the reference frame of the spacecraft and effects such as charging, the formation of electrostatic sheaths and wakes are calculated for given conditions of the space environment. In this paper we present a program used to compute magnetic fields and a number of space plasma and space environment parameters relevant to Low Earth Orbits (LEO) spacecraft-plasma interaction modeling. Magnetic fields are obtained from the International Geophysical Reference Field (IGRF) and plasma parameters are obtained from the International Reference Ionosphere (IRI) model. All parameters are computed in the spacecraft frame of reference as a function of its six Keplerian elements. They are presented in a format that can be used directly in most spacecraft-plasma interaction models. Catalogue identifier: AENY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 270308 No. of bytes in distributed program, including test data, etc.: 2323222 Distribution format: tar.gz Programming language: FORTRAN 90. Computer: Non specific. Operating system: Non specific. RAM: 7.1 MB Classification: 19, 4.14. External routines: IRI, IGRF (included in the package). Nature of problem: Compute magnetic field components, direction of the sun, sun visibility factor and approximate plasma parameters in the reference frame of a Low Earth Orbit satellite. Solution method: Orbit integration, calls to IGRF and IRI libraries and transformation of coordinates from geocentric to spacecraft
Finite time calculations for hard parton production relevant to the quark-gluon plasma
NASA Astrophysics Data System (ADS)
Meiring, Ben; Horowitz, W. A.
2015-10-01
AdS/CFT computations have been used to describe the energy loss of QCD-like particles moving through a strongly coupled plasma, but little is understood regarding the initial conditions of these jets. We use the Schwinger-Keldysh finite-time formalism applied to an interacting scalar field theory to derive perturbative expressions detailing the system which exists during the initial stages of a high energy collision. In this paper we calculate <ϕ>(x) for a scalar Yukawa model, demonstrate the finiteness of the energy momentum tensor for λϕ4 to leading order, and derive an expression for the conditional expectation value of operators to aid in the description jet-like behaviour in interacting theories.
Neoclassical orbit calculations with a full-f code for tokamak edge plasmas
NASA Astrophysics Data System (ADS)
Rognlien, T. D.; Cohen, R. H.; Dorr, M.; Hittinger, J.; Xu, X. Q.; Collela, P.; Martin, D.
2008-11-01
Ion distribution function modifications are considered for the case of neoclassical orbit widths comparable to plasma radial-gradient scale-lengths. Implementation of proper boundary conditions at divertor plates in the continuum TEMPEST code, including the effect of drifts in determining the direction of total flow, enables such calculations in single-null divertor geometry, with and without an electrostatic potential. The resultant poloidal asymmetries in densities, temperatures, and flows are discussed. For long-time simulations, a slow numerical instability develops, even in simplified (circular) geometry with no endloss, which aids identification of the mixed treatment of parallel and radial convection terms as the cause. The new Edge Simulation Laboratory code, expected to be operational, has algorithmic refinements that should address the instability. We will present any available results from the new code on this problem as well as geodesic acoustic mode tests.
Sugama, H.; Nishimura, S.
2008-04-15
A detailed comparison is made between moment-equation methods presented by H. Sugama and S. Nishimura [Phys. Plasmas 9, 4637 (2002)] and by M. Taguchi [Phys. Fluids B 4, 3638 (1992)] for calculating neoclassical transport coefficients in general toroidal plasmas including nonsymmetric systems. It is shown that these methods can be derived from the drift kinetic equation with the same collision model used for correctly taking account of collisional momentum conservation. In both methods, the Laguerre polynomials of the energy variable are employed to expand the guiding-center distribution function and to obtain the moment equations, by which the radial neoclassical transport fluxes and the parallel flows are related to the thermodynamic forces. The methods are given here in the forms applicable for an arbitrary truncation number of the Laguerre-polynomial expansion so that their accuracies can be improved by increasing the truncation number. Differences between results from the two methods appear when the Laguerre-polynomial expansion is truncated up to a finite order because different weight functions are used in them to derive the moment equations. At each order of the truncation, the neoclassical transport coefficients obtained from the Sugama-Nishimura method show the Onsager symmetry and satisfy the ambipolar-diffusion condition intrinsically for symmetric systems. Also, numerical examples are given to show how the transport coefficients converge with the truncation number increased for the two methods.
Garcia-Lechuga, M.; Fuentes, L. M.; Grützmacher, K.; Pérez, C. Rosa, M. I. de la
2014-10-07
We report a detailed characterization of the spatial resolution provided by two-photon absorption spectroscopy suited for plasma diagnosis via the 1S-2S transition of atomic hydrogen for optogalvanic detection and laser induced fluorescence (LIF). A precise knowledge of the spatial resolution is crucial for a correct interpretation of measurements, if the plasma parameters to be analysed undergo strong spatial variations. The present study is based on a novel approach which provides a reliable and realistic determination of the spatial resolution. Measured irradiance distribution of laser beam waists in the overlap volume, provided by a high resolution UV camera, are employed to resolve coupled rate equations accounting for two-photon excitation, fluorescence decay and ionization. The resulting three-dimensional yield distributions reveal in detail the spatial resolution for optogalvanic and LIF detection and related saturation due to depletion. Two-photon absorption profiles broader than the Fourier transform-limited laser bandwidth are also incorporated in the calculations. The approach allows an accurate analysis of the spatial resolution present in recent and future measurements.
NASA Astrophysics Data System (ADS)
Bruggeman, Peter; Degrez, Gérard; Delplancke, Marie-Paule; Gleizes, Alain
2011-05-01
The 11th High-Tech Plasma Processes Conference (HTPP) was held in Brussels, Belgium, 27 June-2 July, 2010. HTPP started as a thermal plasma conference and gradually expanded to include low-temperature plasmas. The conference was founded by Jacques Amouroux and Pierre Fauchais, and aims to bring together different scientific communities to facilitate contacts between science, technology and industry, providing a platform for the exploration of elementary processes and applications in and by plasmas. The first HTPP was held in Odeillo, France, in 1990. Since then it has been held every other year in different European cities: Paris, Aachen, Athens, Strasbourg, Saint-Petersburg, Patras and Brussels. The 11th HTPP conference was attended by 125 participants from 19 countries. The program involved 14 invited talks, 34 contributed talks, 72 posters and a software demonstration and hands-on session for plasma modelling. The 12th HTPP conference will be held 24-28 June 2012, in Bologna, Italy. A larger part of the contributions to the 11th HTPP has been published in the Journal of Physics: Conference Series (JPCS) volume 275, 2011. All invited speakers and other contributors, as selected by the Steering, Scientific and Organizing Committee, were invited to submit a paper based on their contributions for this special issue which is peer reviewed by the journal. Both this special issue and the JPCS volume aim to bring the 11th HTPP to a wider audience. The publications are a nice example of the broad topic range of the conference. The JPCS volume contains papers covering fundamental aspects on radiative processes of thermal plasmas, modelling of thermal arcs and non-thermal RF plasma jets, plasma diagnostics including flow and heat flux measurements of thermal plasmas, radical density measurements and laser-induced breakdown spectroscopy. The applications-oriented contributions of the JPCS volume include plasma spraying, synthesis of (nano-sized) materials, surface
Plasma sources for spacecraft neutralization
NASA Technical Reports Server (NTRS)
Davis, V. A.; Katz, I.; Mandell, M. J.
1990-01-01
The principles of the operation of plasma sources for the neutralization of the surface of a spacecraft traveling in the presence of hot plasma are discussed with special attention given to the hollow-cathode-based plasma contactors. Techiques are developed that allow the calculation of the potentials and particle densities in the near environment of a hollow cathode plasma contactor in both the test tank and the LEO environment. The techniques and codes were validated by comparison of calculated and measured results.
NASA Astrophysics Data System (ADS)
Ghorbanzadeh, Atamalek; Pakmanesh, Nahid; Rastegari, Ali; Abdolghader, Pedram; Feizollah, Peyman; Siadati, Neda
2016-04-01
The performance of an atmospheric pressure pulsed carbon dioxide laser employing surface plasma preionization, produced on a specially patterned printed circuit board (PCB), is reported. The surface plasma is formed due to many tiny plasma channels produced in millimeter sized open circular gaps, made by lithography on one side of PCB. The preionizing plasma is mostly consisted of corona or glow stage and transition to spark one hardly occurs. This type of preionization allows a maximum of 220 J/l energy deposition into the main plasma, while up scaling is yet possible by more optimization of PCB and the pattern. The laser output energy of 1.2 J per pulse with overall efficiency of 7% has been obtained with gas mixture of He:CO2:N2=3:1:1. This type of surface plasma preionization is specifically appropriate for very large volumes and high pressures, where the conventional UV emitting preionizations like spark arrays or corona are not effective.
NASA Astrophysics Data System (ADS)
Han, D.; Wang, J.
2015-12-01
The moon-plasma interactions and the resulting surface charging have been subjects of extensive recent investigations. While many particle-in-cell (PIC) based simulation models have been developed, all existing PIC simulation models treat the surface of the Moon as a boundary condition to the plasma flow. In such models, the surface of the Moon is typically limited to simple geometry configurations, the surface floating potential is calculated from a simplified current balance condition, and the electric field inside the regolith layer cannot be resolved. This paper presents a new full particle PIC model to simulate local scale plasma flow and surface charging. A major feature of this new model is that the surface is treated as an "interface" between two mediums rather than a boundary, and the simulation domain includes not only the plasma but also the regolith layer and the bedrock underneath it. There are no limitations on the surface shape. An immersed-finite-element field solver is applied which calculates the regolith surface floating potential and the electric field inside the regolith layer directly from local charge deposition. The material property of the regolith layer is also explicitly included in simulation. This new model is capable of providing a self-consistent solution to the plasma flow field, lunar surface charging, the electric field inside the regolith layer and the bedrock for realistic surface terrain. This new model is applied to simulate lunar surface-plasma interactions and surface charging under various ambient plasma conditions. The focus is on the lunar terminator region, where the combined effects from the low sun elevation angle and the localized plasma wake generated by plasma flow over a rugged terrain can generate strongly differentially charged surfaces and complex dust dynamics. We discuss the effects of the regolith properties and regolith layer charging on the plasma flow field, dust levitation, and dust transport.
Calculation of the non-inductive current profile in high-performance NSTX plasmas
NASA Astrophysics Data System (ADS)
Gerhardt, S. P.; Fredrickson, E.; Gates, D.; Kaye, S.; Menard, J.; Bell, M. G.; Bell, R. E.; Le Blanc, B. P.; Kugel, H.; Sabbagh, S. A.; Yuh, H.
2011-03-01
The constituents of the current profile have been computed for a wide range of high-performance plasmas in NSTX (Ono et al 2000 Nucl. Fusion 40 557); these include cases designed to maximize the non-inductive fraction, pulse length, toroidal-β or stored energy. In the absence of low-frequency MHD activity, good agreement is found between the reconstructed current profile and that predicted by summing the independently calculated inductive, pressure-driven and neutral beam currents, without the need to invoke any anomalous beam ion diffusion. Exceptions occur, for instance, when there are toroidal Alfvén eigenmode avalanches or coupled m/n = 1/1 + 2/1 kink-tearing modes. In these cases, the addition of a spatially and temporally dependent fast-ion diffusivity can reduce the core beam current drive, restoring agreement between the reconstructed profile and the summed constituents, as well as bringing better agreement between the simulated and measured neutron emission rate. An upper bound on the fast-ion diffusivity of ~0.5-1 m2 s-1 is found in 'MHD-free' discharges, based on the neutron emission, the time rate of change in the neutron signal when a neutral beam is stepped and reconstructed on-axis current density.
Calculation of the Non-Inductive Current Profile in High-Performance NSTX Plasmas
Gerhardt, S P; Gates, D; Kaye, S; Menard, J; Bell, M G; Bell, R E; Le Blanc, B P; Kugel, H; Sabbagh, S A
2011-02-09
The constituents of the current profile have been computed for a wide range of high-performance plasmas in NSTX [M. Ono, et al., Nuclear Fusion 40, 557 (2000)]; these include cases designed to maximize the non-inductive fraction, pulse length, toroidal-β, or stored energy. In the absence of low-frequency MHD activity, good agreement is found between the reconstructed current profile and that predicted by summing the independently calculated inductive, pressure-driven, and neutral beam currents, without the need to invoke any anomalous beam ion diffusion. Exceptions occur, for instance, when there are toroidal Alfven eigenmode avalanches or coupled m/n=1/1+2/1 kink-tearing modes. In these cases, the addition of a spatially and temporally dependent fast ion diffusivity can reduce the core beam current drive, restoring agreement between the reconstructed profile and the summed constituents, as well as bringing better agreement between the simulated and measured neutron emission rate. An upper bound on the fast ion diffusivity of ~0.5-1 m2/sec is found in “MHD-free” discharges, based on the neutron emission, time rate of change of the neutron signal when a neutral beam is stepped, and reconstructed on-axis current density.
NASA Technical Reports Server (NTRS)
Stallcop, J. R.
1974-01-01
The theory for calculating the absorption of laser radiation by hydrogen is outlined for the temperatures and pressures of common laboratory plasmas. Nonhydrogenic corrections for determining the absorption by helium are also included. The coefficients for the absorption of He-Ne laser radiation at the wavelengths of 0.633, 1.15, and 3.39 microns in a H plasma is presented for temperatures in the range from 10,000 to 40,000 K and electron number densities in the range from 10 to the 15th power to 10 to the 18th power per cu cm. The total absorption of a H-He plasma calculated from this theory is compared with the measured absorption. The theoretical composition of the H-He absorption is analyzed with respect to the significant absorption processes, inverse bremsstrahlung, photoionization, resonance excitation, and photodetachment.
Wave Normal and Poynting Vector Calculations using the Cassini Radio and Plasma Wave Instrument
NASA Technical Reports Server (NTRS)
Hospodarsky, G. B.; Averkamp, T. F.; Kurth, W. S.; Gurnett, D. A.; Dougherty, M.; Inan, Umran; Wood, Troy
2001-01-01
Wave normal and Poynting vector measurements from the Cassini radio and plasma wave instrument (RPWS) are used to examine the propagation characteristics of various plasma waves during the Earth flyby on August 18, 1999. Using the five-channel waveform receiver (WFR), the wave normal vector is determined using the Means method for a lightning-induced whistler, equatorial chorus, and a series of low-frequency emissions observed while Cassini was in the magnetosheath. The Poynting vector for these emissions is also calculated from the five components measured by the WFR. The propagation characteristics of the lightning-induced whistler were found to be consistent with the whistler wave mode of propagation, with propagation antiparallel to the magnetic field (southward) at Cassini. The sferic associated with this whistler was observed by both Cassini and the Stanford VLF group at the Palmer Station in Antarctica. Analysis of the arrival direction of the sferic at the Palmer Station suggests that the lightning stroke is in the same sector as Cassini. Chorus was observed very close (within a few degrees) to the magnetic equator during the flyby. The chorus was found to propagate primarily away from the magnetic equator and was observed to change direction as Cassini crossed the magnetic equator. This suggests that the source region of the chorus is very near the magnetic equator. The low-frequency emission in the magnetosheath has many of the characteristics of lion roars. The average value of the angle between the wave normal vector and the local magnetic field was found to be 16 degrees, and the emissions ranged in frequency from 0. 19 to 0.75 f(sub ce), where f(sub ce) is the electron cyclotron frequency. The wave normal vectors of these waves were primarily in one direction for each individual burst (either parallel or antiparallel to the local field) but varied in direction throughout the magnetosheath. This suggests that the sources of the emissions are far from
Ralchenko, Yu.; Abdallah, J. Jr.; Colgan, J.; Fontes, C. J.; Foster, M.; Zhang, H. L.; Bar-Shalom, A.; Oreg, J.; Bauche, J.; Bauche-Arnoult, C.; Bowen, C.; Faussurier, G.; Chung, H.-K.; Hansen, S. B.; Lee, R. W.; Scott, H.; Gaufridy de Dortan, F. de; Poirier, M.; Golovkin, I.; Novikov, V.
2009-09-10
We present calculations of ionization balance and radiative power losses for tungsten in magnetic fusion plasmas. The simulations were performed within the framework of Non-Local Thermodynamic Equilibrium (NLTE) Code Comparison Workshops utilizing several independent collisional-radiative models. The calculations generally agree with each other; however, a clear disagreement with experimental ionization distributions at low temperatures 2 keV
Alis, Rafael; Sanchis-Gomar, Fabian; Lippi, Giuseppe; Roamgnoli, Marco
2016-06-01
The assessment of plasma volume loss (∆PV) induced by exercise can be estimated from changes in hematocrit (Htc) and hemoglobin (Hb), and it is essential when investigating the metabolic or biologic response to exercise of circulating biomarkers. We aimed to ascertain whether the estimation of ∆PV may differ when Hb and Htc are determined by automated hematological analyzer (AHA) versus manual methods. Twenty-five healthy male subjects performed a maximal running incremental exercise. Blood samples were taken before exercise, immediately after exercise, and after a 30-min recovery. Hb and Htc (Htc-AHA) were determined by an AHA. Htc was also determined by microcentrifugation (Htc-M). The ∆PV immediately after exercise and after recovery was calculated. The serum concentrations of several specimens were determined and corrected for ∆PV derived from Htc-AHA (∆PVAHA) and from Htc-M (∆PVM). Htc-M was found to be higher than Htc-AHA at all time points (p < 0.001). However, no differences were observed between ∆PVM and ∆PVAHA either post exercise (∆PVM -12.43% versus ∆PVAHA -12.41%, p = 0.929) or after recovery (∆PVM 1.47% versus ∆PVAHA 1.97%, p = 0.171). No significant differences were found between both ∆PV corrected concentrations of any biomarker (p ≥ 0.076). In conclusion, both AHA and the microcentrifuge may be reliably used to estimate ∆PV during exercise. PMID:25795010
NASA Astrophysics Data System (ADS)
Adineh, V. R.; Coufal, O.; Bartlova, M.
2015-10-01
This work reports theoretical calculations of electrical discharge machining (EDM) radiative properties for mixture systems of N2-C, N2-Cu and N2-W arc plasmas, in the temperature range of 3000-10 000 K, and at 1 and 10 bar pressures. Radiative properties are computed for various plasma sizes as well as vapour proportions. Calculations consider line overlapping with spectrum coverage from 30 to 10 000 nm. Doppler, Natural, Van-der-Waals, Resonance and Stark broadening are taken into account as the line broadening mechanisms. Besides, continuum calculations consider bound-free and free-free emissions along with molecular bands radiation for selected molecular systems. Results show that contamination vapours of EDM electrode have strong influence on the amount of EDM plasma radiation to the surrounding environment. However, comparison of impurities from workpiece with electrode one indicates that Fe vapour has stronger impact on modifying the EDM arc plasma radiative properties, compared to the C, Cu and W species studied in this research.
NASA Astrophysics Data System (ADS)
Tanaka, M.; Yamamoto, K.; Tashiro, S.; Nakata, K.; Yamamoto, E.; Yamazaki, K.; Suzuki, K.; Murphy, A. B.; Lowke, J. J.
2010-11-01
A gas tungsten arc (GTA) was modelled taking into account the contamination of the plasma by metal vapour from the molten anode. The whole region of GTA atmosphere including the tungsten cathode, the arc plasma and the anode was treated using a unified numerical model. A viscosity approximation was used to express the diffusion coefficient in terms of viscosity of the shielding gas and metal vapour. The transient two-dimensional distributions of temperature, velocity of plasma flow and iron vapour concentration were predicted, together with the molten pool as a function of time for a 150 A arc current at atmospheric pressure, both for helium and argon gases. It was shown that the thermal plasma in the GTA was influenced by iron vapour from the molten pool surface and that the concentration of iron vapour in the plasma was dependent on the temperature of the molten pool. GTA on high sulfur stainless steel was calculated to discuss the differences between a low sulfur and a high sulfur stainless steel anode. Helium was selected as the shielding gas because a helium GTA produces more metal vapour than an argon GTA. In the GTA on a high sulfur stainless steel anode, iron vapour and current path were constricted. Radiative emission density in the GTA on high sulfur stainless steel was also concentrated in the centre area of the arc plasma together with the iron vapour although the temperature distributions were almost the same as that in the case of a low sulfur stainless steel anode.
Cucuianu, M; Rus, H G; Cristea, A; Niculescu, F; Bedeleanu, D; Poruţiu, D; Roman, S
1985-04-30
When compared to age-matched normal weight normolipidemic control subjects, plasma factor XIII, plasma fibronectin and serum cholinesterase levels were found to be markedly decreased in patients with decompensated cirrhosis of the liver, not significantly changed in hyperlipoproteinemia type IIa (heterozygous subjects) and increased in hypertriglyceridemic subjects (type IIb and IV) as well as in hyperlipidemic nephrotic patients. A possible accelerated hepatic synthesis of certain plasma proteins including factor XIII and fibronectin in patients with the nephrotic syndrome as well as in endogenous hypertriglyceridemia is envisaged. It is also considered that mural thrombi, richer in factor XIII and fibronectin, would be more resistant to fibrinolysis and more readily attached to subendothelial structures. PMID:3922652
Special Features of the Structure of Copper-containing Products of Plasma Dynamic Synthesis
NASA Astrophysics Data System (ADS)
Ivashutenko, A. S.; Nazarenko, O. B.; Sivkov, A. A.; Saigash, A. S.; Stepanov, K. I.
2015-03-01
Results of investigation of the dispersed, phase, and chemical compositions of products of plasma dynamic synthesis in a high-speed pulsed jet of copper-containing electroerosive plasma flowing into a closed volume with the air atmosphere are presented. Products of synthesis are investigated by the methods of x-ray phase and thermal analyses, electron microscopy, and IR spectroscopy. The structure of the synthesized powder includes metal copper, Cu2O and CuO copper oxides, and hydrated copper hydroxide Cu(OH)2·N2O. Results of investigations of structural changes of the synthesized products during heating in vacuum and air are presented.
NASA Astrophysics Data System (ADS)
Shukurov, Anvar; Sokoloff, Dmitry; Schekochihin, Alexander
2015-08-01
This issue commemorates an outstanding scientist of the twentieth century, Yakov Borisovich Zeldovich, in connection with the centenary of his birth (8 March 1914), with a collection of reviews and research articles broadly related to large-scale random phenomena in astrophysical plasmas.
NASA Astrophysics Data System (ADS)
Coates, A. J.; Wellbrock, A.; Yamauchi, M.
2015-12-01
Within our solar system, the planets, moons, comets and asteroids all have plasma interactions. The interaction depends on the nature of the object, particularly the presence of an atmosphere and a magnetic field. Even the size of the object matters through the finite gyroradius effect and the scale height of cold ions of exospheric origin. It also depends on the upstream conditions, including position within the solar wind or the presence within a planetary magnetosphere. Soon after ESA's Rosetta reached comet Churyumov-Gerasimenko, NASA's Maven and ISRO's Mars Orbiter Mission (MOM) reached Mars, and ESA's Venus Express mission was completed, this issue explores our understanding of plasma interactions with comets, Mars, Venus, and moons in the solar system. We explore the processes which characterise the interactions, such as ion pickup and field draping, and their effects such as plasma escape. Papers are based on data from current and recent space missions, modelling and theory, as we explore our local part of the 'plasma universe'.
NASA Astrophysics Data System (ADS)
Vinko, Sam
2014-10-01
An accurate description of the ionization potential depression (IPD) 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 I present the first experimental investigation of the IPD as a function of ionic charge state in a range of dense Mg, Al and Si plasmas, using the Linac Coherent Light Source X-ray free-electron laser. The measurements show significantly larger IPDs than are predicted by the most commonly used models, such as that of Stewart-Pyatt, or the ion-sphere model of Zimmerman-More. Instead, plasma simulations using finite-temperature density functional theory with excited-state projector augmented-wave potentials show excellent agreement with the experimental results and explain the stronger-than-expected continuum lowering through the electronic structure of the valence states in these strong-coupling conditions, which retain much of their atomic characteristics close to the ion core regions. These results have a profound impact on the understanding and modelling of plasmas over a wide range of warm- and hot-dense matter conditions.
Patacchini, Leonardo; Hutchinson, Ian H.
2008-07-11
The ion drag force on a spherical dust particle immersed in a flowing plasma with an external electric field is self-consistently calculated using the particle-in-cell code SCEPTIC in the entire range of charge-exchange collisionality. Our results, not based on questionable approximations, extend prior analytic calculations valid only in a few limiting regimes. Particular attention is given to the force direction, shown never to be directed opposite to the flow except in the continuum limit, where other forces are of a much stronger magnitude.
NASA Astrophysics Data System (ADS)
Patacchini, Leonardo; Hutchinson, Ian H.
2008-07-01
The ion drag force on a spherical dust particle immersed in a flowing plasma with an external electric field is self-consistently calculated using the particle-in-cell code SCEPTIC in the entire range of charge-exchange collisionality. Our results, not based on questionable approximations, extend prior analytic calculations valid only in a few limiting regimes. Particular attention is given to the force direction, shown never to be directed opposite to the flow except in the continuum limit, where other forces are of a much stronger magnitude.
Ristanović, D; Ristanović, D; Malesević, J; Milutinović, B
1983-01-01
Plasma kinetics of bromsulphalein (BSP) after a single injection into the bloodstream of the rat with total obstruction of the common bile duct was examined. The concentrations of BSP were determined colorimetrically. A monoexponential plus a general first-degree function in time with four unknown parameters was fitted. Two programs were developed for the Texas Instruments 59 programmable calculator to estimate the values of all the parameters by an iteration procedure. The programs executed at about twice normal speed. PMID:6617168
Radiation cooling and gain calculation for C VI 182 A line in C/Se plasma
Nam, C.H.; Valeo, E.; Suckewer, S.; Feldman, U.
1986-04-01
A model is developed which is capable of describing the evolution of gain resulting from both rapid radiative and expansion cooling of a recombining, freely expanding plasma. It is demonstrated for the particular case of a carbon/selenium plasma that the cooling rate which leads to optimal gain can be achieved by adjusting the admixture of an efficiently radiating material (selenium) in the gain medium (carbon). Comparison is made to a recent observation of gain in a recent NRL/Rochester experiment with carbon/selenium plasma for the n = 3 ..-->.. 2 transition in C VI occurring at 182 A. The predicted maximum gain is approx.10 cm/sup -1/, as compared to observation of 2 to 3 cm/sup -1/.
Calculation of Moments from Measurements by the Los Alamos Magnetospheric Plasma Analyzer
M. F. Thomsen; E. Noveroske; J. E. Borovsky; D. J. McComas
1999-05-01
The various steps involved in computing the moments (density, velocity, and temperature) of the ion and electron distributions measured with the Los Alamos Magnetospheric Plasma Analyzer (MPA) are described. The assumptions, constants, and algorithms contained in the FORTRAN code are presented, as well as the output parameters produced by the code.
UAH mathematical model of the variable polarity plasma ARC welding system calculation
NASA Technical Reports Server (NTRS)
Hung, R. J.
1994-01-01
Significant advantages of Variable Polarity Plasma Arc (VPPA) welding process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. A mathematical model is presented to analyze the VPPA welding process. Results of the mathematical model were compared with the experimental observation accomplished by the GDI team.
Goncharov, P R; Ozaki, T; Sudo, S; Tamura, N; Tolstikhina, I Yu; Sergeev, V Yu
2008-10-01
Measurements of energy- and time-resolved neutral hydrogen and helium fluxes from an impurity pellet ablation cloud, referred to as pellet charge exchange or PCX experiments, can be used to study local fast ion energy distributions in fusion plasmas. The estimation of the local distribution function f(i)(E) of fast ions entering the cloud requires knowledge of both the fraction F(0)(E) of incident ions exiting the cloud as neutral atoms and the attenuation factor A(E,rho) describing the loss of fast atoms in the plasma. Determination of A(E,rho), in turn, requires the total stopping cross section sigma(loss) of neutral atoms in the plasma and the Jacobian reflecting the measurement geometry and the magnetic surface shape. The obtained functions F(0)(E) and A(E,rho) enter multiplicatively into the probability density for escaping neutral particle kinetic energy. A general calculation scheme has been developed and realized as a FORTRAN code, which is to be applied for the calculation of f(i)(E) from PCX experimental results obtained with low-Z impurity pellets. PMID:19044625
Zammit, Mark C.; Fursa, Dmitry V.; Bray, Igor
2010-11-15
Electron-hydrogen scattering in weakly coupled hot-dense plasmas has been investigated using the convergent-close-coupling method. The Yukawa-type Debye-Hueckel potential has been used to describe the plasma screening effects. The target structure, excitation dynamics, and ionization process change dramatically as the screening is increased. Excitation cross sections for the 1s{yields}2s,2p,3s,3p,3d and 2s{yields}2p,3s,3p,3d transitions and total and total ionization cross sections for the scattering from the 1s and 2s states are presented. Calculations cover the energy range from thresholds to high energies (250 eV) for various Debye lengths. We find that as the screening increases, the excitation and total cross sections decrease, while the total ionization cross sections increase.
Three-dimensional plasma particle-in-cell calculations of ion thruster backflow contamination
Roy, R.I.S.; Hastings, D.E.; Taylor, S.
1996-10-01
A fully three-dimensional hybrid plasma particle-in-cell model for multi-computer environments was developed to assess the spacecraft backflow contamination of an ion thruster. Results of plume backflow are presented for a 13-cm xenon ion thruster operating with a current level of 0.4 A on a model spacecraft. The computational domain was over 40 m{sup 3} in volume, and used over 35 million particles representing charge-exchange (CEX) xenon ions produced in the plume. Results obtained on a massively parallel 256-node Cray T3D clearly show the plasma density enhancement around the spacecraft due to the CEX ions. Three-dimensional results are compared with the results of a two-dimensional axisymmetric model to explore the three-dimensionality of the backstreaming flowfield. 15 refs., 14 figs., 1 tab.
Stenbøg, Poul; Busk, Troels; Larsen, Fin Stolze
2013-06-01
Severe liver injury result in development of hepatic encephalopathy (HE) and often also in brain edema that is a potentially fatal complication. HE and brain edema are correlated to the level and persistence of hyperammonemia and the presence of systemic inflammation. Treatment of HE and brain edema is based on restoring and keeping normal physiological variables including tonicity, blood gasses, lactate, temperature and vascular resistance by a wide variety of interventions. In addition liver support devices improve the stage of HE, cerebral metabolic rate for oxygen and glucose, and are used either as a bridge to liver transplantation or liver recovery in patients with fulminant hepatic failure and in patients with acute-on-chronic liver failure. This short review will mainly focus on the management and efficacy of doing plasma exchange on HE in patients with acute HE. PMID:23572273
Calculation of two-dimensional plasma sheath with application to radial dust oscillations
Sheridan, T.E.
2005-07-15
Dust particles are often confined radially in a plasma potential well above a cylindrical depression in an otherwise flat electrode. The structure of the two-dimensional, time-independent sheath is computed for this geometry using cold, collisionless ions and Boltzmann electrons. A depression with a radius of 16 Debye lengths and a depth of 2 Debye lengths is modeled for negative electrode biases from 6 to 32 times the electron temperature. The normalized radial oscillation frequency for a dust particle in the well is computed from the sheath potential structure. The model results agree qualitatively with the experimental measurements.
TMRBAR: a code to calculate plasma parameters for tandem-mirror reactors operating in the MARS mode
Campbell, R.B.
1983-08-30
The purpose of this report is to document the plasma power balance model currently used by LLNL to calculate steady state operating points for tandem mirror reactors. The code developed from this model, TMRBAR, has been used to predict the performance and define supplementary heating requirements for drivers used in the Mirror Advanced Reactor Study (MARS) and for the Fusion Power Demonstration (FPD) study. The equations solved included particle and energy balance for central cell and end cell species, quasineutrality at several cardinal points in the end cell region, as well as calculations of volumes, densities and average energies based on given constraints of beta profiles and fusion power output. Alpha particle ash is treated self-consistently, but no other impurity species is treated.
Generalized Lenard-Balescu calculations of electron-ion temperature relaxation in beryllium plasma.
Fu, Zhen-Guo; Wang, Zhigang; Li, Da-Fang; Kang, Wei; Zhang, Ping
2015-09-01
The problem of electron-ion temperature relaxation in beryllium plasma at various densities (0.185-18.5g/cm^{3}) and temperatures [(1.0-8)×10^{3} eV] is investigated by using the generalized Lenard-Balescu theory. We consider the correlation effects between electrons and ions via classical and quantum static local field corrections. The numerical results show that the electron-ion pair distribution function at the origin approaches the maximum when the electron-electron coupling parameter equals unity. The classical result of the Coulomb logarithm is in agreement with the quantum result in both the weak (Γ_{ee}<10^{-2}) and strong (Γ_{ee}>1) electron-electron coupling ranges, whereas it deviates from the quantum result at intermediate values of the coupling parameter (10^{-2}<Γ_{ee}<1). We find that with increasing density of Be, the Coulomb logarithm will decrease and the corresponding relaxation rate ν_{ie} will increase. In addition, a simple fitting law ν_{ie}/ν_{ie}^{(0)}=a(ρ_{Be}/ρ_{0})^{b} is determined, where ν_{ie}^{(0)} is the relaxation rate corresponding to the normal metal density of Be and ρ_{0}, a, and b are the fitting parameters related to the temperature and the degree of ionization 〈Z〉 of the system. Our results are expected to be useful for future inertial confinement fusion experiments involving Be plasma. PMID:26465571
NASA Astrophysics Data System (ADS)
Frolova, A. A.; Khishchenko, K. V.; Charakhch'yan, A. A.
2016-03-01
Integral formulas for the three-dimensional case that give the plasma heating rate per unit volume are obtained using the track method and by integrating the well-known Cauchy problem for the steady-state homogeneous kinetic equation in the Fokker-Planck approximation in the absence of diffusion of the distribution function in the velocity space and under the condition that the velocity of the produced particles is independent on the direction of their escape. It is shown that both integral formulas are equivalent and, in the case of space homogeneous coefficients, turn into the model of local plasma heating away from the domain boundary. In addition to the known direct track method, the inverse method based on the approximation of the integral formula is developed. It is shown that the accuracy of the direct method is significantly decreased in the vicinity of the symmetry axis for not very fine angular grids. In the inverse method, the accuracy is not lost. It is shown that the computational cost of the inverse method can be significantly reduced without the considerable reduction of the computation accuracy.
Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli
2014-03-15
The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model.
Benn, Peter
2016-06-01
Noninvasive prenatal screening (NIPS) for fetal chromosome defects has high sensitivity and specificity but is not fully diagnostic. In response to a desire to provide more information to individual women with positive NIPS results, 2 online calculators have been developed to calculate posttest risk (PTR). Use of these calculators is critically reviewed. There is a mathematically dictated requirement for a precise estimate for the specificity to provide an accurate PTR. This is illustrated by showing that a 0.1% decrease in the value for specificities for trisomies 21, 18, and 13 can reduce the PTR from 79-64% for trisomy 21, 39-27% for trisomy 18, and 21-13% for trisomy 13, respectively. Use of the calculators assumes that sensitivity and specificity are constant for all women receiving the test but there is evidence that discordancy between screening results and true fetal karyotype is more common for older women. Use of an appropriate value for the prior risk is also important and for rare disorders there is considerable uncertainty regarding prevalence. For example, commonly used rates for trisomy 13, monosomy-X, triploidy, and 22q11.2 deletion syndrome can vary by >4-fold and this can translate into large differences in PTR. When screening for rare disorders, it may not be possible to provide a reliable PTR if there is uncertainty over the false-positive rate and/or prevalence. These limitations, per se, do not negate the value of screening for rare conditions. However, counselors need to carefully weigh the validity of PTR before presenting them to patients. Additional epidemiologic and NIPS outcome data are needed. PMID:26772793
NASA Astrophysics Data System (ADS)
Guittienne, Ph; Jacquier, R.; Howling, A. A.; Furno, I.
2015-12-01
Measurements and analysis of a radio-frequency planar antenna are presented for applications in inductively-coupled plasma processing. The network of inductive and capacitive elements exhibits high currents under resonance which are efficient for plasma generation. Mode frequencies and impedances are accurately calculated by accounting for the mutual partial inductances using the impedance matrix. The effect of plasma inductive coupling on mode frequency shift and mode impedance is estimated using the complex image method, giving good agreement with experiment. It is proposed that the complex image method combined with the partial inductance concept (see the accompanying paper, Part I (Howling et al 2015 Plasma Sources Sci. Technol. 24 065014)) offers a general way to calculate the impedance characteristics of inductively-coupled plasma sources in planar geometry.
Convergence of Chapman-Enskog calculation of transport coefficients of magnetized argon plasma
Bruno, D.; Catalfamo, C.; Laricchiuta, A.; Giordano, D.; Capitelli, M.
2006-07-15
Convergence properties of the Chapman-Enskog method in the presence of a magnetic field for the calculation of the transport properties of nonequilibrium partially ionized argon have been studied emphasizing the role of the different collision integrals. In particular, the Ramsauer minimum of electron-argon cross sections affects the convergence of the Chapman-Enskog method at low temperature, while Coulomb collisions affect the results at higher temperatures. The presence of an applied magnetic field mitigates the slow convergence for the components affected by the field.
Equation of state of the one-component plasma derived from precision Monte Carlo calculations
Stringfellow, G.S. Institute of Geophysics and Planetary Physics Lawrence Livermore National Laboratory, Livermore, California 94550 ); DeWitt, H.E. ); Slattery, W.L. )
1990-01-15
Analytical fits to the one-component plasma (OCP) equation of state have been derived for internal energies that have reduced all {ital N}-dependent effects to within the statistical uncertainties introduced by the Monte Carlo computational process, which themselves are very small. Values of {ital N}{approx gt}500 adequately represent the thermodynamic limit. Using the fluid internal energies for only {ital N}=686, various analytical fits are generated, compared, and discussed. The thermal energy is accurately represented by a simple power-series fit with the leading term given by {Gamma}{sup 1/3}, but also requires a small correction to the bcc Madelung term that brings that coefficient down to nearly {minus}0.9, the value derived for hypernetted-chain theory. The fluid thermal energy data are reproduced to better than 0.2% over all {Gamma} by our fit(s). The solid phase requires {ital both} anharmonic terms to be included in the fit, implying that the previous justification for dropping the first anharmonic correction is unwarranted. The location of the fluid-solid phase transition utilizing these new fits yields {Gamma}{sub bcc}=178 and {Gamma}{sub fcc}=192.
Shurygin, R. V.
2012-02-15
A one-dimensional evolution equation for the angle-averaged poloidal momentum of the tokamak plasma is derived in the framework of reduced magnetohydrodynamics with allowance for density inhomogeneity and diamagnetic drift of ions. In addition to fluctuations of the E Multiplication-Sign B drift velocity, the resulting turbulent Reynolds stress tensor includes fluctuations of the ion density and ion pressure, as well as turbulent radial fluxes of particles and heat. It is demonstrated numerically by using a particular example that the poloidal velocity calculated using the refined one-dimensional evolution equation differs substantially from that provided by the simplified model. When passing to the new model, both the turbulent Reynolds force and the Stringer-Winsor force increase, which leads to an increase in the amplitude of the ion poloidal velocity. This, in turn, leads to a decrease in turbulent fluxes of particles and heat due to the effect of shear decorrelation.
Goldman, S. R.; Fernández, J. C.; Hoffman, N. M.; Kindel, J. M.; Langdon, A. Bruce
2004-01-01
The first quad of the NIF provides four nearly collinear f/20 laser beams, which can be treated as a single f/8 beam of maximum energy 16 kJ. We are designing experiments on halfraums in which the composite beam is focused in the plane of the (single) halfraum laser entry hole (LEH) with its symmetry axis collinear with the halfiaum symmetry axis. For most of the calculations, the halfraum diameter is 1.6mm, the LEH is 1.2mm, and axial length is 3.0mm. The incident laser power consists of an early foot followed by a final peak. Peak radiation temperatures for this relatively narrow hohlraum are greater than for wider hohlraums of the same length. Plasma conditions within the halfraum are calculated with Lasnex using azimuthally symmetric, (r,z) geometry, taking into account a polyimide membrane which contains the fill gas (CH{sub 2}) within the halfraum. Estimates for microstructure growth due to the volume crystalline structure within a beryllium slab mounted in the halfraum sidewall are obtained by a post-processor, which applies plasma conditions within the halfraum to an ablatively accelerated, two-dimensional beryllium slab. We present a detailed simulation of the hohlraum conditions resulting from a laser spot of diameter 500 {mu}m, with peak intensity at 3.5 x 10{sup 15} W/cm{sup 2}, a comparison with a simulation with the same power-time profile at an intensity about 1/4 as great, and a comparison with a simulation with more detailed attention to hydro coupling between the gold and gas-fill regions of the hohlraum. We are currently attempting to model the consequences of possible beam filamentation during the pulse.
Kaplan, D
2005-08-31
The purpose of this document is to provide a technically defensible list of distribution coefficients, or Kd values, for use in performance assessment (PA) and special analysis (SA) calculations on the SRS. Only Kd values for radionuclides that have new information related to them or that have recently been recognized as being important are discussed in this report. Some 150 Kd values are provided in this report for various waste-disposal or tank-closure environments: soil, corrosion in grout, oxidizing grout waste, gravel, clay, and reducing concrete environments. Documentation and justification for the selection of each Kd value is provided.
Lyons, B. C.; Jardin, S. C.; Ramos, J. J.
2012-08-15
A new code, the Neoclassical Ion-Electron Solver (NIES), has been written to solve for stationary, axisymmetric distribution functions (f) in the conventional banana regime for both ions and electrons using a set of drift-kinetic equations (DKEs) with linearized Fokker-Planck-Landau collision operators. Solvability conditions on the DKEs determine the relevant non-adiabatic pieces of f (called h). We work in a 4D phase space in which {psi} defines a flux surface, {theta} is the poloidal angle, v is the magnitude of the velocity referenced to the mean flow velocity, and {lambda} is the dimensionless magnetic moment parameter. We expand h in finite elements in both v and {lambda}. The Rosenbluth potentials, {Phi} and {Psi}, which define the integral part of the collision operator, are expanded in Legendre series in cos{chi}, where {chi} is the pitch angle, Fourier series in cos{theta}, and finite elements in v. At each {psi}, we solve a block tridiagonal system for h{sub i} (independent of f{sub e}), then solve another block tridiagonal system for h{sub e} (dependent on f{sub i}). We demonstrate that such a formulation can be accurately and efficiently solved. NIES is coupled to the MHD equilibrium code JSOLVER [J. DeLucia et al., J. Comput. Phys. 37, 183-204 (1980)] allowing us to work with realistic magnetic geometries. The bootstrap current is calculated as a simple moment of the distribution function. Results are benchmarked against the Sauter analytic formulas and can be used as a kinetic closure for an MHD code (e.g., M3D-C{sup 1}[S. C. Jardin et al., Comput. Sci. Discovery 5, 014002 (2012)]).
B.C. Lyons, S.C. Jardin, and J.J. Ramos
2012-06-28
A new code, the Neoclassical Ion-Electron Solver (NIES), has been written to solve for stationary, axisymmetric distribution functions (f ) in the conventional banana regime for both ions and elec trons using a set of drift-kinetic equations (DKEs) with linearized Fokker-Planck-Landau collision operators. Solvability conditions on the DKEs determine the relevant non-adiabatic pieces of f (called h ). We work in a 4D phase space in which Ψ defines a flux surface, θ is the poloidal angle, v is the total velocity referenced to the mean flow velocity, and λ is the dimensionless magnetic moment parameter. We expand h in finite elements in both v and λ . The Rosenbluth potentials, φ and ψ, which define the integral part of the collision operator, are expanded in Legendre series in cos χ , where χ is the pitch angle, Fourier series in cos θ , and finite elements in v . At each ψ , we solve a block tridiagonal system for hi (independent of fe ), then solve another block tridiagonal system for he (dependent on fi ). We demonstrate that such a formulation can be accurately and efficiently solved. NIES is coupled to the MHD equilibrium code JSOLVER [J. DeLucia, et al., J. Comput. Phys. 37 , pp 183-204 (1980).] allowing us to work with realistic magnetic geometries. The bootstrap current is calculated as a simple moment of the distribution function. Results are benchmarked against the Sauter analytic formulas and can be used as a kinetic closure for an MHD code (e.g., M3D-C1 [S.C. Jardin, et al ., Computational Science & Discovery, 4 (2012).]).
Valero, Francisco P. J.; Bush, Brett C.
1999-11-27
Modeled and measured surface insolations are compared with the purpose of evaluating the ability of a radiative transfer model to predict the amount of solar radiation reaching the surface under clear-sky conditions. Model uncertainties are estimated by performing sensitivity studies for variations in aerosol optical depth, aerosol optical properties, water vapor profiles, ozone content, solar irradiance at the top of the atmosphere, and surface albedo. In this fashion, a range of possible calculated values is determined and compared to observations. Experimental errors are evaluated by comparison with independent, simultaneous measurements performed using two World Radiation Reference instrument arrays that were operational for a limited period during SUCCESS. Assuming a mineral aerosol, it is found that there is agreement between calculated and measured fluxes, with differences approximately equal to and within one standard deviation. Such agreement improves further if a layer containing a small amount of carbonaceous aerosol is added. The presence of carbonaceous aerosols is likely because occasional biomass burning activities took place during SUCCESS in the area around the experimental site (the clouds and radiation test bed operated by the Department of Energy in Oklahoma). (c) 2000 American Geophysical Union.
Kluy, N.; Angioni, C.; Camenen, Y.; Peeters, A. G.
2009-12-15
The toroidal momentum transport in the presence of trapped electron mode microinstabilities in tokamak plasmas is studied by means of quasilinear gyrokinetic calculations. In particular, the role of the Coriolis drift in producing an inward convection of toroidal momentum is investigated. The Coriolis drift term has been implemented in the gyrokinetic code GS2 [W. Dorland et al., Phys. Rev. Lett. 85, 5579 (2000)] specifically for the completion of this work. A benchmark between the GS2 implementation of the Coriolis drift and the implementations included in two other gyrokinetic codes is presented. The numerical calculations show that in the presence of trapped electron modes, despite of a weaker symmetry breaking of the eigenfunctions with respect to the case of ion temperature gradient modes, a pinch of toroidal momentum is produced in most conditions. The toroidal momentum viscosity is also computed, and found to be small as compared with the electron heat conductivity, but significantly larger than the ion heat conductivity. In addition, interesting differences are found in the dependence of the toroidal momentum pinch as a function of collisionality between trapped electron modes and ion temperature gradient modes. The results identify also parameter domains in which the pinch is predicted to be small, which are also of interest for comparisons with the experiments.
ERIC Educational Resources Information Center
Middlesex County Vocational and Technical High Schools, New Brunswick, NJ.
A project studied a method to overcome possible embarrassment and "math anxiety" of secondary level students in remedial and special needs math classes and to sustain interest in drill practice while allowing for better utilization of the teacher's time. One Monroe Calculator "Classmate 88" programmed calculator was placed in each of five remedial…
NASA Astrophysics Data System (ADS)
Borodkina, I. E.; Komm, M.; Tsvetkov, I. V.
2015-08-01
Simple analytical formulas are derived for calculation of the electric field potential distribution in the magnetic pre-layer and the Debye layer near the plasma facing surfaces. It is shown that the calculated potential profiles are in good agreement with the dependences of the potential distribution on the magnetic field inclination obtained by solving the magnetic hydrodynamic (MHD) equations and modeling using the PIC code SPICE2. Dependences of the angular distribution of ions incident on the surface of plasma facing elements on the magnetic field inclination are obtained. Results of calculations demonstrate that the surface areas, on which the magnetic field is incident at sliding angles, are critical from the viewpoint of the increase of sputtering.
NASA Astrophysics Data System (ADS)
Habib, A. A. M.
2014-06-01
The mean probability of photon capture for the resonance lines emitted by a neutral fluorine atom is calculated assuming a Voigt line shape. The calculations allow a quantitative estimate of the self-absorption effect of spectral lines of neutral fluorine atoms occurring far below the ultraviolet (UV) spectral range. The calculations are made for the bound-bound resonance lines emitted at 95.48, 77.81, 95.85, 79.44 and 77.94 nm in the case of SF6-N2 thermal plasma mixture. The dependence of the mean probability of photon capture on the Doppler and collision (Stark, resonance and van der Waals) broadening mechanisms is considered. The same method is equally applied to free-bound transitions of the recombination continuum. The variation of the mean probability of photon capture with the temperature, the SF6 proportions and the size of the plasma are considered. The results obtained may be of practical importance in plasma modeling and plasma diagnostics. In view of its simplicity, the method may also be applied to laser-induced breakdown spectroscopy (LIBS) spectral analysis.
Barriga-Carrasco, Manuel D; Casas, David; Morales, Roberto
2016-03-01
The energy loss of argon ions in a target depends on their velocity and charge density. At the energies studied in this work, it depends mostly on the free and bound electrons in the target. Here the random-phase approximation is used for analyzing free electrons at any degeneracy. For the plasma-bound electrons, an interpolation between approximations for low and high energies is applied. The Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its equilibrium charge state Q(eq). This latter criterion implies that the equilibrium charge state depends slightly on the electron density and temperature of the plasma. On the other hand, the effective charge Q(eff) is obtained as the ratio between the energy loss of the argon ion and that of the proton for the same plasma conditions. This effective charge Q(eff) is larger than the equilibrium charge state Q(eq) due to the incorporation of the BK charge distribution. Though our charge-state estimations are not exactly the same as the experimental values, our energy loss agrees quite well with the experiments. It is noticed that the energy loss in plasmas is higher than that in the same cold target of about, ∼42-62.5% and increases with carbon plasma ionization. This confirms the well-known enhanced plasma stopping. It is also observed that only a small part of this energy loss enhancement is due to an increase of the argon charge state, namely only ∼2.2 and 5.1%, for the partially and the fully ionized plasma, respectively. The other contribution is connected with a better energy transfer to the free electrons at plasma state than to the bound electrons at solid state of about, ∼38.8-57.4%, where higher values correspond to a fully ionized carbon plasma. PMID:27078472
NASA Astrophysics Data System (ADS)
Barriga-Carrasco, Manuel D.; Casas, David; Morales, Roberto
2016-03-01
The energy loss of argon ions in a target depends on their velocity and charge density. At the energies studied in this work, it depends mostly on the free and bound electrons in the target. Here the random-phase approximation is used for analyzing free electrons at any degeneracy. For the plasma-bound electrons, an interpolation between approximations for low and high energies is applied. The Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its equilibrium charge state Qeq. This latter criterion implies that the equilibrium charge state depends slightly on the electron density and temperature of the plasma. On the other hand, the effective charge Qeff is obtained as the ratio between the energy loss of the argon ion and that of the proton for the same plasma conditions. This effective charge Qeff is larger than the equilibrium charge state Qeq due to the incorporation of the BK charge distribution. Though our charge-state estimations are not exactly the same as the experimental values, our energy loss agrees quite well with the experiments. It is noticed that the energy loss in plasmas is higher than that in the same cold target of about, ˜42 -62.5 % and increases with carbon plasma ionization. This confirms the well-known enhanced plasma stopping. It is also observed that only a small part of this energy loss enhancement is due to an increase of the argon charge state, namely only ˜2.2 and 5.1 % , for the partially and the fully ionized plasma, respectively. The other contribution is connected with a better energy transfer to the free electrons at plasma state than to the bound electrons at solid state of about, ˜38.8 -57.4 % , where higher values correspond to a fully ionized carbon plasma.
Florido, R.; Rodriguez, R.; Gil, J. M.; Rubiano, J. G.; Martel, P.; Minguez, E.; Sauvan, R.; Mancini, R.
2008-10-22
This work describes ABAKO/RAPCAL, a flexible computational package for the study of population kinetics and radiative properties of non-equilibrium plasmas in a wide range of physical conditions. The code was developed looking for an optimal compromise between accuracy and computational cost. ABAKO/RAPCAL assembles a set of simple analytical models which yield substantial savings of computer resources, but yet still providing good comparisons with more elaborated codes and experimental data. Here we present some results to show the ABAKO/RAPCAL capabilities to calculate the charge distribution and radiative properties of both low- and high-Z plasmas. Finally, an application for K-shell spectroscopic determination of the electron temperature and density of laser-produced plasmas is also shown.
Wang, Qingqing; Mesaros, Clementina; Blair, Ian A
2016-09-01
Estrogen measurements play an important role in the clinical evaluation of many endocrine disorders as well as in research on the role of hormones in human biology and disease. It remains an analytical challenge to quantify estrogens and their metabolites in specimens from special populations including older men, children, postmenopausal women and women receiving aromatase inhibitors. Historically, immunoassays have been used for measuring estrogens and their metabolites in biological samples for risk assessment. However, the lack of specificity and accuracy of immunoassay-based methods has caused significant problems when interpreting data generated from epidemiological studies and across different laboratories. Stable isotope dilution (SID) methodology coupled with liquid chromatography-selected reaction monitoring-mass spectrometry (LC-SRM/MS) is now accepted as the 'gold-standard' to quantify estrogens and their metabolites in serum and plasma due to improved specificity, high accuracy, and the ability to monitor multiple estrogens when compared with immunoassays. Ultra-high sensitivity can be obtained with pre-ionized derivatives when using triple quadruple mass spectrometers in the selected reaction monitoring (SRM) mode coupled with nanoflow LC. In this review, we have examined the special issues related to utilizing ultra-high sensitivity SID LC-SRM/MS-based methodology to accurately quantify estrogens and their metabolites in the serum and plasma from populations with low estrogen levels. The major issues that are discussed include: sample preparation for both unconjugated and conjugated estrogens, derivatization, chromatographic separation, matrix effects, and assay validation. PMID:26767303
NASA Astrophysics Data System (ADS)
Hey, J. D.
2015-09-01
On the basis of the original definition and analysis of the vector operator by Pauli (1926 Z. Phys. 36 336-63), and further developments by Flamand (1966 J. Math. Phys. 7 1924-31), and by Becker and Bleuler (1976 Z. Naturforsch. 31a 517-23), we consider the action of the operator on both spherical polar and parabolic basis state wave functions, both with and without direct use of Pauli’s identity (Valent 2003 Am. J. Phys. 71 171-75). Comparison of the results, with the aid of two earlier papers (Hey 2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641-64, Hey 2007 J. Phys. B: At. Mol. Opt. Phys. 40 4077-96), yields a convenient ladder technique in the form of a recurrence relation for calculating the transformation coefficients between the two sets of basis states, without explicit use of generalized hypergeometric functions. This result is therefore very useful for application to Stark effect and impact broadening calculations applied to high-n radio recombination lines from tenuous space plasmas. We also demonstrate the versatility of the Runge-Lenz-Pauli vector operator as a means of obtaining recurrence relations between expectation values of successive powers of quantum mechanical operators, by using it to provide, as an example, a derivation of the Kramers-Pasternack relation. It is suggested that this operator, whose potential use in Stark- and Zeeman-effect calculations for magnetically confined fusion edge plasmas (Rosato, Marandet and Stamm 2014 J. Phys. B: At. Mol. Opt. Phys. 47 105702) and tenuous space plasmas ( H II regions) has not been fully explored and exploited, may yet be found to yield a number of valuable results for applications to plasma diagnostic techniques based upon rate calculations of atomic processes.
Zock, J P; Rispens, P; Zijlstra, W G
1981-08-01
As a contribution to solving the problem of pH disequilibrium in arterial blood, the results of two modes of gas exchange in the lung have been calculated using an equilibrium state model of the blood. In both cases the HCO3-/Cl-exchange was assumed to occur after the gas exchange in the pulmonary capillaries. When the gas exchange was assumed to be dependent on intra-erythrocytic carbonic anhydrase, the plasma pH in the arterial blood increased. When plasma erythrocytes were assumed to equilibrate separately with the alveolar gas due to pressure of extra-erythrocytic carbonic anhydrase, plasma pH in the arterial blood decreased. In each case there was a slight increase in pCO2 after the blood had left the pulmonary capillaries. PMID:6793999
NASA Astrophysics Data System (ADS)
Vergunova, G. A.; Ivanov, E. M.; Rozanov, Vladislav B.
2003-02-01
The spectral radiative losses are investigated in a plasma under conditions typical of a plasma produced upon irradiation of solid targets by high-intensity (up to 1017 W cm-2 ultrashort (10-13-10-9 s) laser pulses. The comparison of the calculated X-ray spectra with the experimental data for aluminum and carbon plasmas shows their satisfactory agreement. These studies made it possible to test the methods in use and to conclude that it is necessary to introduce supplements into the collision — radiation model for calculating the optical characteristics of a nonequilibrium plasma of complex chemical composition.
NASA Astrophysics Data System (ADS)
Silin, I.; Toffoletto, F.; Wolf, R.; Sazykin, S. Y.
2013-12-01
We present a finite-volume MHD code for simulations of magnetospheric dynamics of the plasma sheet and the inner magnetosphere. The code uses staggered non-uniform Cartesian grids to preserve the divergence-free magnetic fields, along with various numerical approximations and flux limiters for the plasma variables. The code can be initialized with empirical magnetic field models, such as the Tsyganenko models along with pressure information from either the Tsyganenko-Mukai models, or observational data, such as DMSP pressure maps. Artificial "friction term" can be added to the momentum equation, which turns the MHD code into "magnetofriction" code which can be used to construct approximate equilibrium solutions. We demonstrate some applications for our code, in both the "magnetofriction" and MHD mode, including relaxation of the empirical models to equilibrium and the evolution of a plasma bubble in the near magnetotail. The latter MHD simulation results exhibit oscillations about their equilibrium position in agreement with recent observations.
NASA Technical Reports Server (NTRS)
Oya, H.
1971-01-01
The dispersion curves have been computed for a wide range of wavelengths from electromagnetic waves to electrostatic waves in a magnetoactive warm plasma with a Maxwellian velocity distribution function. The computation was carried out mainly for the perpendicular propagation mode. The upper hybrid resonance is the connection point of the electrostatic waves and the electromagnetic waves. The electrostatic waves not associated with the upper hybrid resonance are subjected to electron cyclotron damping when the wavelength becomes long. Oblique propagation is allowed for the electrostatic waves in a frequency range from the plasma frequency to the upper hybrid resonance frequency in the long-wavelength region where Landau damping can be neglected and where the electrostatic mode smoothly connects to the electromagnetic X-mode. In a slightly inhomogeneous plasma, the Bernstein-mode electrostatic wave can escape by being converted into the O-mode electromagnetic wave; two reflections take place during this escape process.
Whitley, Heather D.; Scullard, Christian R.; Benedict, Lorin X.; Castor, John I.; Randles, Amanda; Glosli, James N.; Richards, David F.; Desjarlais, Michael P.; Graziani, Frank R.
2014-08-31
Here, we present a discussion of kinetic theory treatments of linear electrical and thermal transport in hydrogen plasmas, for a regime of interest to inertial confinement fusion applications. In order to assess the accuracy of one of the more involved of these approaches, classical Lenard-Balescu theory, we perform classical molecular dynamics simulations of hydrogen plasmas using 2-body quantum statistical potentials and compute both electrical and thermal conductivity from out particle trajectories using the Kubo approach. Our classical Lenard-Balescu results employing the identical statistical potentials agree well with the simulations.
Whitley, Heather D.; Scullard, Christian R.; Benedict, Lorin X.; Castor, John I.; Randles, Amanda; Glosli, James N.; Richards, David F.; Desjarlais, Michael P.; Graziani, Frank R.
2015-12-04
Here, we present a discussion of kinetic theory treatments of linear electrical and thermal transport in hydrogen plasmas, for a regime of interest to inertial confinement fusion applications. In order to assess the accuracy of one of the more involved of these approaches, classical Lenard-Balescu theory, we perform classical molecular dynamics simulations of hydrogen plasmas using 2-body quantum statistical potentials and compute both electrical and thermal conductivity from out particle trajectories using the Kubo approach. Our classical Lenard-Balescu results employing the identical statistical potentials agree well with the simulations.
NASA Technical Reports Server (NTRS)
Bathke, C. G.
1976-01-01
Electron energy distribution functions were calculated in a U235 plasma at 1 atmosphere for various plasma temperatures and neutron fluxes. The distributions are assumed to be a summation of a high energy tail and a Maxwellian distribution. The sources of energetic electrons considered are the fission-fragment induced ionization of uranium and the electron induced ionization of uranium. The calculation of the high energy tail is reduced to an electron slowing down calculation, from the most energetic source to the energy where the electron is assumed to be incorporated into the Maxwellian distribution. The pertinent collisional processes are electron-electron scattering and electron induced ionization and excitation of uranium. Two distinct methods were employed in the calculation of the distributions. One method is based upon the assumption of continuous slowing and yields a distribution inversely proportional to the stopping power. An iteration scheme is utilized to include the secondary electron avalanche. In the other method, a governing equation is derived without assuming continuous electron slowing. This equation is solved by a Monte Carlo technique.
Berezhkovskiy, Leonid M
2016-08-01
An uncommon innovative consideration of the well-stirred linear physiologically based pharmacokinetic model and the drug plasma concentration-time profile, which is measured in routine intravenous bolus pharmacokinetic study, was applied for the calculation of the drug time course in human tissues. This cannot be obtained in the in vivo pharmacokinetic study. The physiological parameters of the organ such as organ tissue volume, organ blood flow rate, and its vascular volume were used in the calculation. The considered method was applied to calculate the time course of midazolam, alprazolam, quinidine, and diclofenac in human organs or tissues. The suggested method might be applied for the prediction of drug concentration-time profile in tissues and consequently the drug concentration level in the targeted tissue, as well as the possible undesirable toxic levels in other tissues. PMID:27290628
NASA Astrophysics Data System (ADS)
Amarante-Segundo, G.; Elfimov, A. G.; Galvão, R. M. O.; Ross, D. W.; Nascimento, I. C.
2001-01-01
The current and plasma flows driven by ponderomotive forces are calculated for tokamak plasmas, using a kinetic code in the Alfvén range of frequencies. The rf (radio frequency) ponderomotive force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation (electron Landau damping and transit time magnetic pumping). Finally, the rf force is balanced by the viscous force in the fluid momentum response to the rf fields in the plasma. The relative magnitudes of the different forces for kinetic and global Alfvén waves with low phase velocities are explicitly calculated. It is shown that, dissipating in electrons, Alfvén waves can drive ion flow via the gradient force, which is dominated in m=0-sideband harmonic resonance induced by toroidal mode coupling. Estimates of power requirements to drive substantial poloidal flow in the Tokamak Chauffage Alfvén wave heating experiment in Brazil (TCABR) [L. Ruchko, M. C. Andrade, R. M. O. Galvão, Nucl. Fusion 30, 503 (1996)] are made.
Hannachi, R.; Cressault, Y.; Teulet, Ph.; Gleizes, A.; Ben Lakhdar, Z.; Taieeb, G.
2007-09-19
The resonance escape factors for the lines emitted by a neutral magnesium atom MgI at 285.2127 nm (3 {sup 1}S-3 {sup 1}P) and of ionic magnesium MgII at 279.5528 nm (3 {sup 2}S-3 {sup 2}P) are calculated assuming a Voigt profile and in the case of MgCl{sub 2}-water plasma. The dependence of the escape factor on the optical thickness {tau}{sub 0} from the line center which itself depends on the two main spectral line shape broadening mechanisms (pressure and Doppler effects) are considered. The variation of the resonance escape factors with the temperature and the MgCl{sub 2} molar proportion are also investigated. This calculation is useful for the application of laser induced breakdown spectroscopy in the quantitative analysis of elemental composition.
NASA Astrophysics Data System (ADS)
Boumans, P. W. J. M.
About 600 prominent lines for inductively-coupled plasma-atomic emission spectrometry (ICP-AES) using an argon ICP were studied with the triple objective of (1) compiling a library of prominent lines for spectrographic general survey analysis in this laboratory, (2) comparing the detection limits and sensitivities of the lines with literature data, in particular those in the author's Line Coincidence Tables for ICP-AES [Pergamon Press, Oxford (1980)], and (3) providing a list of lines with "universal" sensitivities that can be generally used for semiquantitative analysis. A 50 MHz ICP operated under compromise conditions and spectrographic detection were used. The latter limited the wavelength region of the prominent lines covered to a range between 235 and 446 nm. For 598 lines listed in the Line Coincidence Tables (LCT) the paper presents the visually estimated detection limits and an assessment of band interferences in regions of ±0.05nm about the prominent lines. Similar data are presented for 88 computer predicted, supplementary prominent lines [Spectrochim. Acta 36B, 169 (1981)] for which the predictions came true. For the 383 prominent lines located between 252 and 446 nm densitometrically determined detection limits and sensitivities are given. The sensitivities were converted to a "universal scale", independent of the spectral characteristics of the optics and the detector. The results of the visual and densitometric determinations are compared mutually and with the data given in the LCT, which are primarily based on the experimental work of Winge et al. [Appt. Specirosc. 33, 206 (1979)]; consequently the present paper also assesses the extent to which data for prominent lines can be transferred from the one ICP to the other, if both are operated under compromise conditions. The conversion of sensitivities on the "universal scale" to a scale applicable to a particular apparatus using the corresponding spectral distributions of the background intensity is
Rudenko, V. V.
2010-12-15
The problem of laser deposition with allowance for thermal radiation transport inside and outside the laser torch is considered in a multigroup approximation. The energy fluxes of laser torch thermal radiation onto a target in the far and near zones are calculated as functions of time and the character of the exposure. It is shown that absorption of thermal fluxes in the substrate and target in the course of laser deposition results in their substantial heating. The possibility of diagnosing thermal radiation fluxes from the laser torch by using photodetectors is demonstrated.
NASA Astrophysics Data System (ADS)
Murakami, Tomoyuki; Okuno, Yoshihiro
2008-06-01
We describe quasi-three-dimensional numerical simulations of a high-performance nonequilibrium-plasma magnetohydrodynamic (MHD) electrical power generator using a slightly divergent configuration. The slightly divergent generator provides greater isentropic efficiency (IE) than a highly divergent generator when an identical enthalpy extraction ratio (EER) is obtained. The inherent feature of a small divergent geometry is clarified; MHD energy conversion is accompanied by less entropy production as well as less gas expansion. The orientation of the performance improvement on an IE-EER map is consistent with the theoretically predicted orientation, which is formulated using an algebraic method based on classical thermodynamic results for supersonic compressible fluid dynamics. The power-generating performance indicators, IE and EER, are clearly determined by modified magnetic flux density, that is, the square of magnetic flux density divided by total inflow pressure. A virtual operating condition for a practical closed-cycle MHD system is proposed considering the relationships between the applied magnetic flux density, the total inflow pressure and the total pressure gradient throughout the generator. This paper is the first part of a duology.
NASA Astrophysics Data System (ADS)
Valipa, Mayur S.; Aydil, Eray S.; Maroudas, Dimitrios
2004-11-01
We report a direct, statistically significant calculation of the surface reactivity of the SiH 3 radical on hydrogenated amorphous silicon (a-Si:H) using molecular-dynamics simulations of repeated impingement of SiH 3 radicals on growth surfaces of smooth a-Si:H films over the temperature range 475-800 K. SiH 3 can either incorporate into the film by adsorbing onto a surface Si dangling bond or inserting into Si-Si bonds (sticking), or abstract surface H through Eley-Rideal (ER) or Langmuir-Hinshelwood (LH) pathways to produce SiH 4 gas, or react with another surface SiH 3 to desorb as Si 2H 6 (recombination), or leave the film by reflection or desorption. The overall surface reaction probability, β, includes both radical sticking and recombination. In agreement with experimental measurements, β is almost constant over the temperature range studied, as are the probabilities for sticking and recombination, s and γ, respectively; the calculated mean value of β is 0.47 ± 0.03. Energetic analysis of the various surface reactions shows that radical adsorption, radical insertion, and ER abstraction are barrierless processes, which explains the measured temperature independence of β. LH abstraction is activated, but competes with disilane formation, yielding a temperature-independent γ. Also, LH abstraction leads to H elimination from a-Si:H during growth and can partly explain the experimentally measured temperature dependence of the H content in the a-Si:H film.
Ivanov, A. A. Martynov, A. A. Medvedev, S. Yu. Poshekhonov, Yu. Yu.
2015-03-15
In the MHD tokamak plasma theory, the plasma pressure is usually assumed to be isotropic. However, plasma heating by neutral beam injection and RF heating can lead to a strong anisotropy of plasma parameters and rotation of the plasma. The development of MHD equilibrium theory taking into account the plasma inertia and anisotropic pressure began a long time ago, but until now it has not been consistently applied in computational codes for engineering calculations of the plasma equilibrium and evolution in tokamak. This paper contains a detailed derivation of the axisymmetric plasma equilibrium equation in the most general form (with arbitrary rotation and anisotropic pressure) and description of the specialized version of the SPIDER code. The original method of calculation of the equilibrium with an anisotropic pressure and a prescribed rotational transform profile is proposed. Examples of calculations and discussion of the results are also presented.
NASA Astrophysics Data System (ADS)
Ivanov, A. A.; Martynov, A. A.; Medvedev, S. Yu.; Poshekhonov, Yu. Yu.
2015-03-01
In the MHD tokamak plasma theory, the plasma pressure is usually assumed to be isotropic. However, plasma heating by neutral beam injection and RF heating can lead to a strong anisotropy of plasma parameters and rotation of the plasma. The development of MHD equilibrium theory taking into account the plasma inertia and anisotropic pressure began a long time ago, but until now it has not been consistently applied in computational codes for engineering calculations of the plasma equilibrium and evolution in tokamak. This paper contains a detailed derivation of the axisymmetric plasma equilibrium equation in the most general form (with arbitrary rotation and anisotropic pressure) and description of the specialized version of the SPIDER code. The original method of calculation of the equilibrium with an anisotropic pressure and a prescribed rotational transform profile is proposed. Examples of calculations and discussion of the results are also presented.
NASA Technical Reports Server (NTRS)
Jones, Alun R.
1940-01-01
This report has been prepare in response to a request for information from an aircraft company. A typical example was selected for the presentation of an approximate method of calculation of the relative humidity required to prevent frosting on the inside of a plastic window in a pressure type cabin on a high speed airplane. The results of the study are reviewed.
Programmable calculator stress analysis
Van Gulick, L.A.
1983-01-01
Advanced programmable alphanumeric calculators are well suited for closed-form calculation of pressure-vessel stresses. They offer adequate computing power, portability, special programming features, and simple interactive execution procedures. Representative programs that demonstrate calculator capabilities are presented. Problems treated are stress and strength calculations in thick-walled pressure vessels and the computation of stresses near head/pressure-vessel junctures.
NASA Astrophysics Data System (ADS)
Pollmann, D.; Leis, F.; Tölg, G.; Tschöpel, P.; Broekaert, J. A. C.
1994-12-01
The use of inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace elements in Al 2O 3 powders is reported. Special interest is given to a preconcentration of the trace elements by on-line coupling of chromatography to ICP-MS. This is based on the complexation of Co, Cu, Cr, Fe, Ga, Mn, Ni, V and Zn with hexamethylene-dithiocarbamate (HMDC), their preconcentration on a C18 RP column by reversed phase liquid chromatography and their elution with CH 3OH-H 2O mixtures. A direct coupling of the HPLC system to the ICP-MS has been realized by high pressure pneumatic nebulization using desolvation. With the Chromatographie method developed, removal of the AI by at least 99% was achieved. For the trace elements V, Fe, Ni, Co, Cu and Ga, high and reproducible recoveries (ranging from 96-99%) were reached. The method developed has been shown to considerably enhance the power of detection as compared with direct procedures, namely down to 0.02-0.16 ( μg/g for V and Fe, respectively. The possibilities of the method are shown by the determinations of V, Mn, Fe, Ni, Co, Cu, Zn and Ga at the μg/g level in A1 2O 3 powders. The accuracy of the method at the 0.06 to 9.0 μg/g level for Co and Fe, respectively, is demonstrated by a comparison with results of independent methods from the literature.
ERIC Educational Resources Information Center
Clarke, Jacqueline
2001-01-01
Presents unique ways to create special rituals that recognize individual students' achievements and milestones. Ideas include throwing a send-off party for a student who is moving; holding monthly birthday luncheons; choosing an ambassador to accompany new students around school; and making a lost tooth container that students can use to safely…
Slater, C.O.
1992-01-01
The DRC2 code, which couples MASH or MASHX adjoint leakages with DORT 2-D discrete ordinates forward directional fluences, is described. The forward fluences are allowed to vary both axially and radially over the coupling surface, as opposed to the strictly axial variation allowed by the predecessor DRC code. Input instructions are presented along with descriptions and results from several sample problems. Results from the sample problems are used to compare DRC2 with DRC, DRC2 with DORT, and DRC2 with itself for the case of x-y dependence versus no x-y dependence of the forward fluence. The test problems demonstrate that for small systems DRC and DRC2 give essentially the same results. Some significant differences are noted for larger systems. Additionally, DRC2 results with no x-y dependence of the forward directional fluences are practically the same as those calculated by DRC.
Molecular dynamic study of pressure fluctuations spectrum in plasma
NASA Astrophysics Data System (ADS)
Bystryi, R. G.
2015-11-01
Pressure of plasma is calculated by using classical molecular dynamics method. The formula based on virial theorem was used. Spectrum pressure's fluctuations of singly ionized non-ideal plasma are studied. 1/f-like spectrum behavior is observed. In other words, flicker noise is observed in fluctuations of pressure equilibrium non-ideal plasma. Relations between the obtained result and pressure fluctuations within the Gibbs and Einstein approaches are discussed. Special attention is paid to features of calculating the pressure in strongly coupled systems.
Plasma simulation and fusion calculation
NASA Astrophysics Data System (ADS)
Buzbee, B. L.
Particle-in-cell (PIC) models are widely used in fusion studies associated with energy research and in certain fluid dynamical studies. Parallel computation is relevant to them because (1) PIC models are not amenable to a lot of vectorization - about 50% of the total computation is vectorized in the average model; (2) the volume of data processed by PIC models typically necessitates use of secondary storage with an attendant requirements for high-speed I/O; and (3) PIC models exist today whose implementation requires a computer 10 to 100 times faster than the Cray-1. Parallel formulation of PIC models for master/slave architectures and ring architectures is discussed. Because interprocessor communication is a decisive factor in the overall efficiency of a parallel system, division of these models into large granules that can be executed in parallel with relatively little need for communication is shown. Measurements of speedup obtained from experiments on the UNIVAC 1100/84 and the Denelcor HEP are also reported.
Plasma simulation and fusion calculation
Buzbee, B.L.
1983-01-01
Particle-in-cell (PIC) models are widely used in fusion studies associated with energy research. They are also used in certain fluid dynamical studies. Parallel computation is relevant to them because (1) PIC models are not amenable to a lot of vectorization - about 50% of the total computation can be vectorized in the average model; (2) the volume of data processed by PIC models typically necessitates use of secondary storage with an attendant requirements for high-speed I/O; and (3) PIC models exist today whose implementation requires a computer 10 to 100 times faster than the Cray-1. This paper discusses parallel formulation of PIC models for master/slave architectures and ring architectures. Because interprocessor communication can be a decisive factor in the overall efficiency of a parallel system, we show how to divide these models into large granules that can be executed in parallel with relatively little need for communication. We also report measurements of speedup obtained from experiments on the UNIVAC 1100/84 and the Denelcor HEP.
Bao, Junwei Lucas; Truhlar, Donald G
2016-04-21
The growth of anionic silicon hydride clusters is a critically important process in nanodusty plasmas. In the current study, we focus on the formation of homologs of silylene (Sin+1H2n+2(-), n = 3, 4) and silyl (SinH2n+1(-), n = 4, 5) anions via anion-neutral reaction pathways. Species like silyl or silylene anions and their related elementary reactions, which are involved in the formation of silicon hydride clusters, were not used in developing exchange-correlation (xc) density functionals (i.e., they were not included in the training set of semiempirical density functionals); therefore, we explored the accuracy of various widely used xc density functionals based on reaction energies and barrier heights. Among the 21 density functionals we tested, M06-2X has the best performance for a hybrid functional, and MN15-L has the best performance for a local functional. Thermal rate constants of the elementary reactions involved in the reaction mechanism are calculated using M06-2X and multistructural canonical variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT). The pressure dependence of unimolecular isomerization reactions is treated with system-specific quantum RRK theory (SS-QRRK) and the Lindemann-Hinshelwood mechanism. PMID:27009479
NASA Astrophysics Data System (ADS)
Brualla, L.; Mayorga, P. A.; Flühs, A.; Lallena, A. M.; Sempau, J.; Sauerwein, W.
2012-11-01
Retinoblastoma is the most common eye tumour in childhood. According to the available long-term data, the best outcome regarding tumour control and visual function has been reached by external beam radiotherapy. The benefits of the treatment are, however, jeopardized by a high incidence of radiation-induced secondary malignancies and the fact that irradiated bones grow asymmetrically. In order to better exploit the advantages of external beam radiotherapy, it is necessary to improve current techniques by reducing the irradiated volume and minimizing the dose to the facial bones. To this end, dose measurements and simulated data in a water phantom are essential. A Varian Clinac 2100 C/D operating at 6 MV is used in conjunction with a dedicated collimator for the retinoblastoma treatment. This collimator conforms a ‘D’-shaped off-axis field whose irradiated area can be either 5.2 or 3.1 cm2. Depth dose distributions and lateral profiles were experimentally measured. Experimental results were compared with Monte Carlo simulations’ run with the penelope code and with calculations performed with the analytical anisotropic algorithm implemented in the Eclipse treatment planning system using the gamma test. penelope simulations agree reasonably well with the experimental data with discrepancies in the dose profiles less than 3 mm of distance to agreement and 3% of dose. Discrepancies between the results found with the analytical anisotropic algorithm and the experimental data reach 3 mm and 6%. Although the discrepancies between the results obtained with the analytical anisotropic algorithm and the experimental data are notable, it is possible to consider this algorithm for routine treatment planning of retinoblastoma patients, provided the limitations of the algorithm are known and taken into account by the medical physicist and the clinician. Monte Carlo simulation is essential for knowing these limitations. Monte Carlo simulation is required for optimizing the
Skiff, Fred; Davidson, Ronald C.
2013-05-15
Each year, the annual meeting of the APS Division of Plasma Physics (DPP) brings together a broad representation of the many active subfields of plasma physics and enjoys an audience that is equally diverse. The meeting was well attended and largely went as planned despite the interventions of hurricane Sandy which caused the city of Providence to shut-down during the first day of the conference. The meeting began on Monday morning with a review of the physics of cosmic rays, 2012 being the 100th year since their discovery, which illustrated the central importance of plasma physics to astrophysical problems. Subsequent reviews covered the importance of tokamak plasma boundaries, progress towards ignition on the National Ignition Facility (NIF), and magnetized plasma turbulence. The Maxwell prize address, by Professor Liu Chen, covered the field of nonlinear Alfvén wave physics. Tutorial lectures were presented on the verification of gyrokinetics, new capabilities in laboratory astrophysics, magnetic flux compression, and tokamak plasma start-up.
NASA Astrophysics Data System (ADS)
Skiff, Fred; Davidson, Ronald C.
2013-05-01
Each year, the annual meeting of the APS Division of Plasma Physics (DPP) brings together a broad representation of the many active subfields of plasma physics and enjoys an audience that is equally diverse. The meeting was well attended and largely went as planned despite the interventions of hurricane Sandy which caused the city of Providence to shut-down during the first day of the conference. The meeting began on Monday morning with a review of the physics of cosmic rays, 2012 being the 100th year since their discovery, which illustrated the central importance of plasma physics to astrophysical problems. Subsequent reviews covered the importance of tokamak plasma boundaries, progress towards ignition on the National Ignition Facility (NIF), and magnetized plasma turbulence. The Maxwell prize address, by Professor Liu Chen, covered the field of nonlinear Alfvén wave physics. Tutorial lectures were presented on the verification of gyrokinetics, new capabilities in laboratory astrophysics, magnetic flux compression, and tokamak plasma start-up.
Relativistic Thomson Scatter from Factor Calculation
Energy Science and Technology Software Center (ESTSC)
2009-11-01
The purpose of this program is calculate the fully relativistic Thomson scatter from factor in unmagnetized plasmas. Such calculations are compared to experimental diagnoses of plasmas at such facilities as the Jupiter laser facility here a LLNL.
Liu, Chang; Dodin, Ilya Y.
2015-08-15
The nonlinear frequency shift is derived in a transparent asymptotic form for intense Langmuir waves in general collisionless plasma. The formula describes both fluid and kinetic effects simultaneously. The fluid nonlinearity is expressed, for the first time, through the plasma dielectric function, and the kinetic nonlinearity accounts for both smooth distributions and trapped-particle beams. Various known limiting scalings are reproduced as special cases. The calculation avoids differential equations and can be extended straightforwardly to other nonlinear plasma waves.
NASA Astrophysics Data System (ADS)
Sobel'man, Igor I.; Shevelko, A. P.; Yakushev, O. F.; Knight, L. V.; Turley, R. S.
2003-01-01
The results of investigation of a capillary discharge plasma, used as a source of intense VUV radiation and soft X-rays, are presented. The plasma was generated during the discharge of low-inductance condensers in a gas-filled ceramic capillary. Intense line radiation was observed in a broad spectral range (30-400 Å) in various gases (CO2, Ne, Ar, Kr, Xe). The absolute radiation yield for the xenon discharge was ~5 mJ (2π sr)-1 pulse-1 within a spectral band of width 9 Å at 135 Å. Such a radiation source can be used for various practical applications, such as EUV projection lithography, microscopy of biological objects in a 'water window', reflectometry, etc.
NASA Astrophysics Data System (ADS)
Livadiotis, George
2015-03-01
Empirical kappa distributions provide a straightforward replacement of the Maxwell distribution for systems out of thermal equilibrium such as space plasmas. Kappa distributions have become increasingly widespread across space physics with the number of relevant publications following, remarkably, an exponential growth rate. However, a breakthrough in the field came with the connection of kappa distributions with the framework of nonextensive statistical mechanics. This introductory paper clarifies fundamental physical concepts and provides mathematical formulations of the theory of kappa distributions, which are a consequence of the connection of kappa distributions with a solid statistical background. Among others, the paper presents the existence of a consistent definition of temperature in systems out of thermal equilibrium described by kappa distributions, the physical meaning of the kappa index, and the formulation of the kappa distribution of a Hamiltonian. In addition, the paper examines the most frequent values of kappa indices in space plasmas. Statistical analysis reveals trends between the characteristic values of density, temperature, and kappa index of space plasmas. Finally, understanding the kinetic interpretation of the temperature as the mean kinetic energy, and of the kappa index as the correlation of kinetic energies, helps to develop all the possible formulations of isotropic/anisotropic kappa distributions.
NASA Technical Reports Server (NTRS)
Alfven, H.
1986-01-01
Traditionally the views on the cosmic environent have been based on observations in the visual octave of the electromagnetic spectrum, during the last half-century supplemented by infrared and radio observations. Space research has opened the full spectrum. Of special importance are the X-ray-gamma-ray regions, in which a number of unexpected phenomena have been discovered. Radiations in these regions are likely to originate mainly from magnetised cosmic plasmas. Such a medium may also emit synchrotron radiation which is observable in the radio region. If a model of the universe is based on the plasma phenomena mentioned it is found that the plasma universe is drastically different from the traditional visual universe. Information about the plasma universe can also be obtained by extrapolation of laboratory experiments and magnetospheric in situ measurements of plasmas. This approach is possible because it is likely that the basic properties of plasmas are the same everywhere. In order to test the usefulness of the plasma universe model it is applied to cosmogony. Such an approach seems to be rather successful. For example, the complicated structure of the Saturnian C ring can be accounted for. It is possible to reconstruct certain phenomena 4 to 5 billions of years ago with an accuracy of better than 1%.
ERIC Educational Resources Information Center
Braswell, Ray, Ed.
This document contains the following papers on special needs instruction and technology: (1) "Hawaii Special Education Teacher Induction" (Kalena Oliva and Quinn Avery); (2) "The Impact of Group v Individual Use of Hypermedia-Based Instruction" (Lewis R. Johnson, Louis P. Semrau, and Gail E. Fitzgerald); (3) "Assistive Technology Meets…
Fang, Ferric C.
2014-01-01
As the body of scientific knowledge in a discipline increases, there is pressure for specialization. Fields spawn subfields that then become entities in themselves that promote further specialization. The process by which scientists join specialized groups has remarkable similarities to the guild system of the middle ages. The advantages of specialization of science include efficiency, the establishment of normative standards, and the potential for greater rigor in experimental research. However, specialization also carries risks of monopoly, monotony, and isolation. The current tendency to judge scientific work by the impact factor of the journal in which it is published may have roots in overspecialization, as scientists are less able to critically evaluate work outside their field than before. Scientists in particular define themselves through group identity and adopt practices that conform to the expectations and dynamics of such groups. As part of our continuing analysis of issues confronting contemporary science, we analyze the emergence and consequences of specialization in science, with a particular emphasis on microbiology, a field highly vulnerable to balkanization along microbial phylogenetic boundaries, and suggest that specialization carries significant costs. We propose measures to mitigate the detrimental effects of scientific specialism. PMID:24421049
ERIC Educational Resources Information Center
Ayoub, Ayoub B.
2006-01-01
In this article, the author takes up the special trinomial (1 + x + x[squared])[superscript n] and shows that the coefficients of its expansion are entries of a Pascal-like triangle. He also shows how to calculate these entries recursively and explicitly. This article could be used in the classroom for enrichment. (Contains 1 table.)
NASA Astrophysics Data System (ADS)
Tarasenko, Viktor F.; Yakovlenko, Sergei I.
2003-02-01
The use of electron beams for pumping dense gases made it possible to obtain lasing on atomic and molecular transitions in different spectral ranges and to develop high-power pulsed lasers. N.G. Basov and coworkers made a substantial contribution to the formation and advancement of this field. A brief review of the research on efficient elevated-pressure active media and high-power pulsed lasers utilising plasmas produced both by an electron beam and an electron-beam-controlled discharge is presented. These are excimer and exciplex lasers, lasers utilising atomic transitions in xenon and neon, an Ar —N2 mixture laser, a molecular nitrogen ion laser, and a high-pressure CO2 laser. Data obtained in the investigation of the radiation of rare-gas halide complexes are given.
Binary collision rates of relativistic thermal plasmas. I Theoretical framework
NASA Technical Reports Server (NTRS)
Dermer, C. D.
1985-01-01
Binary collision rates for arbitrary scattering cross sections are derived in the case of a beam of particles interacting with a Maxwell-Boltzmann (MB) plasma, or in the case of two MB plasmas interacting at generally different temperatures. The expressions are valid for all beam energies and plasma temperatures, from the nonrelativistic to the extreme relativistic limits. The calculated quantities include the reaction rate, the energy exchange rate, and the average rate of change of the squared transverse momentum component of a monoenergetic particle beam as a result of scatterings with particles of a MB plasma. Results are specialized to elastic scattering processes, two-temperature reaction rates, or the cold plasma limit, reproducing previous work.
ERIC Educational Resources Information Center
Lavendel, Giuliana
1977-01-01
Discusses problems involved in maintaining special scientific or engineering libraries, including budget problems, remote storage locations, rental computer retrieval systems, protecting trade secrets, and establishing a magnetic tape library. (MLH)
ERIC Educational Resources Information Center
Zimmer, Phil
1986-01-01
Specialized publications such as "Opera News,""Gourmet," and "Forbes" can bring an institution's story to targeted audiences. The experiences of Chautauqua Institution are described. Some of the benefits of marketing articles to these publications are discussed. (MLW)
Airborne antenna pattern calculations
NASA Technical Reports Server (NTRS)
Knerr, T. J.; Schaffner, P. R.; Mielke, R. R.; Gilreath, M. C.
1980-01-01
A procedure for numerically calculating radiation patterns of fuselage-mounted airborne antennas using the Volumetric Pattern Analysis Program is presented. Special attention is given to aircraft modeling. An actual case study involving a large commercial aircraft is included to illustrate the analysis procedure.
Hur, M.; Kang, K.D.; Hong, S.H.
1997-12-31
In this study, the plasma characteristics of a high power nontransferred plasma torch with hollow electrodes are investigated in the atmospheric condition by analyzing the distributions of plasma temperature, velocity and current density. Typical assumptions of steady state, axisymmetry, local thermodynamic equilibrium (LTE) and optically thin plasma are adopted in a two-dimensional magnetohydrodynamic (MHD) modeling of thermal plasma with a special treatment of arc spot positions. A control volume method and the modified SIMPLER algorithm are used for solving the governing equations numerically, i.e., conservation equations of mass, momentum, and energy along with the equations describing the {Kappa}-{var_epsilon} model for turbulence and the current continuity for arc discharge. The distributions of plasma temperature, velocity, and current density are calculated in various operation conditions such as gas species, gas flowrate, input current, and electrode geometry. The calculated results of plasma characteristics in various operations can be useful to determine the design parameters of the high power plasma torch of hollow electrode type for incinerating the hospital and municipal solid wastes.
Electrostatic ion thruster optics calculations
NASA Technical Reports Server (NTRS)
Whealton, John H.; Kirkman, David A.; Raridon, R. J.
1992-01-01
Calculations have been performed which encompass both a self-consistent ion source extraction plasma sheath and the primary ion optics including sheath and electrode-induced aberrations. Particular attention is given to the effects of beam space charge, accelerator geometry, and properties of the downstream plasma sheath on the position of the electrostatic potential saddle point near the extractor electrode. The electron blocking potential blocking is described as a function of electrode thickness and secondary plasma processes.
Sun, Yu; Liu, Yanan; Li, Rui; Xue, Gang; Ognier, Stéphanie
2016-07-01
This study investigated the degradation of a model organic compound, reactive blue (RB-19), in aqueous solution using a needle-plate non-thermal plasma (NTP) reactor, which was operated using three gas atmospheres (Ar, air, O2) at room temperature and atmospheric pressure. The relative discharge and degradation parameters, including the peak to peak applied voltage, power, ozone generation, pH, decolorization rates, energy density and the total organic carbon (TOC) reduction were analyzed to determine the various dye removal efficiencies. The decolorization rate for Ar, air and O2 were 59.9%, 49.6% and 89.8% respectively at the energy density of 100 kJ/L. The best TOC reduction was displayed by Ar with about 8.8% decrease, and 0% with O2 and air atmospheres. This phenomenon could be explained by the formation of OH• and O3 in the Ar and O2 atmospheres, which are responsible for increased mineralization and efficient decolorization. A one-dimension model was developed using software COMSOL to simulate the RB-19-ozone reaction and verify the experiments by comparing the simulated and experimental results. It was determined that ozone plays the most important role in the dye removal process, and the ozone contribution rate ranged from 0.67 to 0.82. PMID:27124311
ERIC Educational Resources Information Center
Wiant, Sarah K.; Lynch, Clifford; Nevins, Kate; Juergens, Bonnie
1998-01-01
Contains three special reports: developments in copyright law, 1997 (World Intellectual Property Organization (WIPO) legislation, Ashcroft Bill, No Electronic Theft Act, database protection, Conference on Fair Use (CONFU), judicial decisions, principles for licensing electronic resources, and Uniform Commercial Code Article 2B); Internet2 and the…
ERIC Educational Resources Information Center
Vander Weele, Maribeth
1992-01-01
Thomas Hehir, special education chief of Chicago Public Schools, is evangelist of integrating children with disabilities into regular classrooms. By completely reorganizing department viewed as political patronage dumping ground, Hehir has made remarkable progress in handling large number of children awaiting evaluation and placement in special…
NASA Astrophysics Data System (ADS)
Sartori, L.; Murdin, P.
2000-11-01
The special theory of relativity (SR), developed by ALBERT EINSTEIN in 1905, represents a revolutionary change in the human conception of the nature of space and time. According to SR, space and time are not absolute but must be viewed as components of a single entity, SPACE-TIME. This idea has numerous important implications, both conceptual and practical....
ERIC Educational Resources Information Center
Hammond, Carol; And Others
1992-01-01
Six articles discuss librarians as mediators in special circumstances. Highlights include the reference librarian and the information paraprofessional; effective reference mediation for nontraditional public library users, including mentally impaired patrons and illiterate adults; the academic librarian's role in the education process; and…
Kopittke, Peter M; Blamey, F Pax C; Wang, Peng; Menzies, Neal W
2011-07-01
Manganese (Mn) is an essential micronutrient for plant growth but is often toxic in acid or waterlogged soils. Using cowpea (Vigna unguiculata L. Walp.) grown with 0.05-1500 μM Mn in solution, two short-term (48 h) solution culture experiments examined if the effects of cations (Ca, Mg, Na, Al, or H) on Mn nutrition are related to the root cells' plasma membrane (PM) surface potential, ψ(0)(0). When grown in solutions containing levels of Mn that were toxic, both relative root elongation rate (RRER) and root tissue Mn concentration were more closely related to the activity of Mn(2+) at the outer surface of the PM, {Mn(2+)}(0)(0) (R(2)=0.812 and 0.871) than to its activity in the bulk solution, {Mn(2+)}(b) (R(2)=0.673 and 0.769). This was also evident at lower levels of Mn (0.05-10 μM) relevant to studies investigating Mn as an essential micronutrient (R(2)=0.791 versus 0.590). In addition, changes in the electrical driving force for ion transport across the PM influenced both RRER and the Mn concentration in roots. The {Mn(2+)}(b) causing a 50% reduction in root growth was found to be c. 500 to >1000 μM (depending upon solution composition), whilst the corresponding value was 3300 μM when related to {Mn(2+)}(0)(0). Although specific effects such as competition are not precluded, the data emphasize the importance of non-specific electrostatic effects in the Mn nutrition of cowpea seedlings over a 1×10(5)-fold range of Mn concentration in solution. PMID:21511910
ERIC Educational Resources Information Center
Weatherly, Julie J.
2000-01-01
School districts are on safer legal ground if they recommend appropriate educational services for each special-needs child, convene parents and school personnel for Individual Education Plan meetings, make placement decisions based on individualized, thorough evaluations; document alternative options; develop behavior-management programs, and use…
NASA Astrophysics Data System (ADS)
Woodhouse, Nicholas M. J.
This course on special relativity emphasizes the coordinate-free and tensorial approach to Einstein's theory. The author encourages the reader to look at problems from a four-dimensional point of view, so preparing them for further study in relativistic physics, gravitation and cosmology. The book will be especially appealing to students with a mathematical bent and those who like brevity and clarity of reasoning.
Piron, R.; Blenski, T.
2011-02-15
The numerical code VAAQP (variational average atom in quantum plasmas), which is based on a fully variational model of equilibrium dense plasmas, is applied to equation-of-state calculations for aluminum, iron, copper, and lead in the warm-dense-matter regime. VAAQP does not impose the neutrality of the Wigner-Seitz ion sphere; it provides the average-atom structure and the mean ionization self-consistently from the solution of the variational equations. The formula used for the electronic pressure is simple and does not require any numerical differentiation. In this paper, the virial theorem is derived in both nonrelativistic and relativistic versions of the model. This theorem allows one to express the electron pressure as a combination of the electron kinetic and interaction energies. It is shown that the model fulfills automatically the virial theorem in the case of local-density approximations to the exchange-correlation free-energy. Applications of the model to the equation-of-state and Hugoniot shock adiabat of aluminum, iron, copper, and lead in the warm-dense-matter regime are presented. Comparisons with other approaches, including the inferno model, and with available experimental data are given. This work allows one to understand the thermodynamic consistency issues in the existing average-atom models. Starting from the case of aluminum, a comparative study of the thermodynamic consistency of the models is proposed. A preliminary study of the validity domain of the inferno model is also included.
Piron, R; Blenski, T
2011-02-01
The numerical code VAAQP (variational average atom in quantum plasmas), which is based on a fully variational model of equilibrium dense plasmas, is applied to equation-of-state calculations for aluminum, iron, copper, and lead in the warm-dense-matter regime. VAAQP does not impose the neutrality of the Wigner-Seitz ion sphere; it provides the average-atom structure and the mean ionization self-consistently from the solution of the variational equations. The formula used for the electronic pressure is simple and does not require any numerical differentiation. In this paper, the virial theorem is derived in both nonrelativistic and relativistic versions of the model. This theorem allows one to express the electron pressure as a combination of the electron kinetic and interaction energies. It is shown that the model fulfills automatically the virial theorem in the case of local-density approximations to the exchange-correlation free-energy. Applications of the model to the equation-of-state and Hugoniot shock adiabat of aluminum, iron, copper, and lead in the warm-dense-matter regime are presented. Comparisons with other approaches, including the inferno model, and with available experimental data are given. This work allows one to understand the thermodynamic consistency issues in the existing average-atom models. Starting from the case of aluminum, a comparative study of the thermodynamic consistency of the models is proposed. A preliminary study of the validity domain of the inferno model is also included. PMID:21405914
Analysis of Power Model for Linear Plasma Device
NASA Astrophysics Data System (ADS)
Zhang, Weiwei; Deng, Baiquan; Zuo, Haoyi; Zheng, Xianjun; Cao, Xiaogang; Xue, Xiaoyan; Ou, Wei; Cao, Zhi; Gou, Fujun
2016-08-01
A single cathode linear plasma device has been designed and constructed to investigate the interactions between plasma and materials at the Sichuan University. In order to further investigate the Ohmic power of the device, the output heat load on the specimen and electric potential difference (between cathode and anode) have been tested under different discharge currents. This special power distribution in the radial direction of the plasma discharge channel has also been discussed and described by some improved integral equations in this paper; it can be further simplified as P ∝ α‑2 in one-parameter. Besides, we have measured the power loss of the channel under different discharge currents by the calorimetric method, calculated the effective power of the device and evaluated the performances of the plasma device through the power efficiency analysis. supported by International Thermonuclear Experimental Reactor (ITER) Program (No. 2013GB114003) and National Natural Science Foundation of China (Nos. 11275135 and 11475122)
Plasma heating power dissipation in low temperature hydrogen plasmas
Komppula, J. Tarvainen, O.
2015-10-15
A theoretical framework for power dissipation in low temperature plasmas in corona equilibrium is developed. The framework is based on fundamental conservation laws and reaction cross sections and is only weakly sensitive to plasma parameters, e.g., electron temperature and density. The theory is applied to low temperature atomic and molecular hydrogen laboratory plasmas for which the plasma heating power dissipation to photon emission, ionization, and chemical potential is calculated. The calculated photon emission is compared to recent experimental results.
High-performance simulations for atmospheric pressure plasma reactor
NASA Astrophysics Data System (ADS)
Chugunov, Svyatoslav
Plasma-assisted processing and deposition of materials is an important component of modern industrial applications, with plasma reactors sharing 30% to 40% of manufacturing steps in microelectronics production. Development of new flexible electronics increases demands for efficient high-throughput deposition methods and roll-to-roll processing of materials. The current work represents an attempt of practical design and numerical modeling of a plasma enhanced chemical vapor deposition system. The system utilizes plasma at standard pressure and temperature to activate a chemical precursor for protective coatings. A specially designed linear plasma head, that consists of two parallel plates with electrodes placed in the parallel arrangement, is used to resolve clogging issues of currently available commercial plasma heads, as well as to increase the flow-rate of the processed chemicals and to enhance the uniformity of the deposition. A test system is build and discussed in this work. In order to improve operating conditions of the setup and quality of the deposited material, we perform numerical modeling of the plasma system. The theoretical and numerical models presented in this work comprehensively describe plasma generation, recombination, and advection in a channel of arbitrary geometry. Number density of plasma species, their energy content, electric field, and rate parameters are accurately calculated and analyzed in this work. Some interesting engineering outcomes are discussed with a connection to the proposed setup. The numerical model is implemented with the help of high-performance parallel technique and evaluated at a cluster for parallel calculations. A typical performance increase, calculation speed-up, parallel fraction of the code and overall efficiency of the parallel implementation are discussed in details.
Calibration of the ISEE plasma composition experiment
NASA Technical Reports Server (NTRS)
Baugher, C. R.; Olsen, R. C.; Reasoner, D. L.
1986-01-01
The Plasma Composition experiment on the ISEE-1 satellite was designed to measure ions from 1 to 16 amu, at energies from near zero to 16 keV. The two nearly identical flight instruments were calibrated by means of preflight laboratory tests and in-flight data comparisons. This document presents most of the details of those efforts, with special emphasis on the low energy (0 to 100 eV) portion of the instrument response. The analysis of the instrument includes a ray-tracing calculation, which follows an ensemble of test particles through the detector.
Special issue on filamentation
NASA Astrophysics Data System (ADS)
Li, Ruxin; Milchberg, Howard; Mysyrowicz, André
2014-05-01
Journal of Physics B: Atomic, Molecular and Optical Physics is delighted to announce a forthcoming special issue on filamentation, to appear in the spring of 2015, and invites you to submit a paper. This special issue will attempt to give an overview of the present status of this field in order to create synergies and foster future developments. The issue is open to papers on the following issues: Theoretical advances on filamentation. Self-focusing and collapse. Filamentation in various media. Pulse self-compression and ultrafast processes in filaments. Molecular alignment and rotation. Filamentation tailoring. Interaction between filaments. Filament weather and pollution control. Filament induced condensation and precipitation. Terahertz science with filaments. Lasing in filaments. Filament induced molecular excitation and reaction. Electric discharge and plasma. Cross-disciplinary applications. Novel concepts related to these topics are particularly welcome. Please submit your article by 1 October 2014 (expected web publication: spring 2015) using our website http://mc04.manuscriptcentral.com/jphysb-iop. Submissions received after this date will be considered for the journal, but may not be included in the special issue. The issue will be edited by Ruxin Li, Howard Milchberg and André Mysyrowicz.
Albers, R.C.; Gubernatis, J.E.
1981-01-01
The efficiency of four different Brillouin-zone integration schemes including the uniform mesh, special point method, special directions method, and Holas method are compared for calculating moments of the harmonic phonon frequencies of the solid one-component plasma. Very accurate values for the moments are also presented. The Holas method for which weights and integration points can easily be generated has roughly the same efficiency as the special directions method, which is much superior to the uniform mesh and special point methods for this problem.
Characteristics of multiarc plasma devices
NASA Astrophysics Data System (ADS)
Klubnikin, V. S.; Smirnov, B. G.
1985-03-01
Multiarc plasma devices such as plasmatrons operate with lower arc currents than single-arc counterparts, which not contributes to a higher efficiency but also extends the life of electrodes. Typically, reduction of the arc current for producing an air plasma from 400 A to 100 A or further to 50 A lengthens the life of zirconium electrodes from 24 h to 400 h and 1600 h, respectively. The electric arcs can be connected in series or in parallel. A series connection features high arching stability but requires special mixing chambers for prevention of mutual arc shunting. A parallel connection eliminates this drawback but limits the arcing stability, the latter decreasing as the number of arcs in parallel increases. A third possibility is a multiarc device with separate voltage supplies and a single common control system. The performance of any multiarc plasma device is determined by its current-voltage characteristic. For determining the optimum operating mode, not only the dependence of the arc voltage on the arc current but also its dependence on the arc length, the channel diameter, the gas flow rate, and the gas pressure were evaluated. Calculations are based on semiempirical and dimensional analysis of experimental data from about 200 measurements over wide ranges of variable parameters for discharge in argon.
National Institute of Standards and Technology Data Gateway
SRD 166 MEMS Calculator (Web, free access) This MEMS Calculator determines the following thin film properties from data taken with an optical interferometer or comparable instrument: a) residual strain from fixed-fixed beams, b) strain gradient from cantilevers, c) step heights or thicknesses from step-height test structures, and d) in-plane lengths or deflections. Then, residual stress and stress gradient calculations can be made after an optical vibrometer or comparable instrument is used to obtain Young's modulus from resonating cantilevers or fixed-fixed beams. In addition, wafer bond strength is determined from micro-chevron test structures using a material test machine.
10 CFR 766.102 - Calculation methodology.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 10 Energy 4 2014-01-01 2014-01-01 false Calculation methodology. 766.102 Section 766.102 Energy DEPARTMENT OF ENERGY URANIUM ENRICHMENT DECONTAMINATION AND DECOMMISSIONING FUND; PROCEDURES FOR SPECIAL ASSESSMENT OF DOMESTIC UTILITIES Procedures for Special Assessment § 766.102 Calculation methodology....
10 CFR 766.102 - Calculation methodology.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 10 Energy 4 2012-01-01 2012-01-01 false Calculation methodology. 766.102 Section 766.102 Energy DEPARTMENT OF ENERGY URANIUM ENRICHMENT DECONTAMINATION AND DECOMMISSIONING FUND; PROCEDURES FOR SPECIAL ASSESSMENT OF DOMESTIC UTILITIES Procedures for Special Assessment § 766.102 Calculation methodology....
10 CFR 766.102 - Calculation methodology.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 10 Energy 4 2011-01-01 2011-01-01 false Calculation methodology. 766.102 Section 766.102 Energy DEPARTMENT OF ENERGY URANIUM ENRICHMENT DECONTAMINATION AND DECOMMISSIONING FUND; PROCEDURES FOR SPECIAL ASSESSMENT OF DOMESTIC UTILITIES Procedures for Special Assessment § 766.102 Calculation methodology....
10 CFR 766.102 - Calculation methodology.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 4 2013-01-01 2013-01-01 false Calculation methodology. 766.102 Section 766.102 Energy DEPARTMENT OF ENERGY URANIUM ENRICHMENT DECONTAMINATION AND DECOMMISSIONING FUND; PROCEDURES FOR SPECIAL ASSESSMENT OF DOMESTIC UTILITIES Procedures for Special Assessment § 766.102 Calculation methodology....
NASA Astrophysics Data System (ADS)
Wu, Yue; Cai, Yan; Sun, Dawei; Zhu, Junjie; Wu, Yixiong
2014-12-01
A novel lateral restraint method was proposed to suppress plasma plume of high power CO2 laser welding using a pair of copper blocks with cooling water. The plasma plume was observed with a high-speed camera, and its core zone and periphery zone were investigated based on the specific processing algorithm. With the specially designed shifting unit, the spectrum of plasma plume was scanned both in 1-D and 2-D mode. Based on the selected spectral lines, electron temperature and electron number density of plasma plume were calculated. The characteristics of plasma plume, as well as the restraint mechanism, were discussed both in 1-D and 2-D mode. Results showed that the cooling effect, blowing effect and the static pressure were enhanced by the lateral restraint, and the restraint effect of the near-wall low-temperature area limited the expansion of plasma plume greatly.
NASA Astrophysics Data System (ADS)
Volokitin, G. G.; Skripnikova, N. K.; Sinitsyn, V. A.; Volokitin, O. G.; Shekhovtsov, V. V.; Vaschenko, S. P.; Kuz'min, V. I.
2016-01-01
Plasma technology was developed to create protective-decorative coatings on the wood surfaces. Experimental investigation on applying the protective coating using the low-temperature plasma energy as well as studies of the distribution of temperature fields over the section of the treated workpiece have been carried out, and the calculated results have been compared with the experimental data.
What's so special about cholesterol?
Mouritsen, Ole G; Zuckermann, Martin J
2004-11-01
Cholesterol (or other higher sterols such as ergosterol and phytosterols) is universally present in large amounts (20-40 mol%) in eukaryotic plasma membranes, whereas it is universally absent in the membranes of prokaryotes. Cholesterol has a unique ability to increase lipid order in fluid membranes while maintaining fluidity and diffusion rates. Cholesterol imparts low permeability barriers to lipid membranes and provides for large mechanical coherence. A short topical review is given of these special properties of cholesterol in relation to the structure of membranes, with results drawn from a variety of theoretical and experimental studies. Particular focus is put on cholesterol's ability to promote a special membrane phase, the liquid-ordered phase, which is unique for cholesterol (and other higher sterols like ergosterol) and absent in membranes containing the cholesterol precursor lanosterol. Cholesterol's role in the formation of special membrane domains and so-called rafts is discussed. PMID:15726825
Arc plasma jets of a nontransferred plasma torch
Kang, K.D.; Hong, S.H.
1996-02-01
The dc plasma torches have been widely used as clean plasma sources for plasma processings such as plasma spraying and synthesis. The plasma flow of a nontransferred plasma torch used for thermal plasma processings is produced by the arc-gas interactions between a cathode tip and an anode nozzle and expands as a jet through the nozzle. In this work, numerically calculated images of the arc plasma characteristics are found over the entire plasma region, including both an arc-gas interacting region inside the torch and a jet expanding region outside the torch. A numerical model used assumes a local thermodynamic equilibrium (LTE) with near-electrode phenomena and compressible flow effects. The computational system is described by a two-dimensional (2-D) axisymmetric model which is solved for plasma temperature and velocity by a control volume approach with the modified SIMPLER algorithm in a real torch geometry.
How to Patch Active Plasma and Collisionless Sheath: Practical Guide
Kaganovich, Igor D.
2002-08-22
Most plasmas have a very thin sheath compared with the plasma dimension. This necessitates separate calculations of the plasma and sheath. The Bohm criterion provides the boundary condition for calculation of plasma profiles. To calculate sheath properties, a value of electric field at the plasma-sheath interface has to be specified in addition to the Bohm criterion. The value of the boundary electric field and robust procedure to approximately patch plasma and collisionless sheath with a very good accuracy are reported.
Neyrinck, Marleen M; Vrielink, Hans
2015-02-01
It's important to work smoothly with your apheresis equipment when you are an apheresis nurse. Attention should be paid to your donor/patient and the product you're collecting. It gives additional value to your work when you are able to calculate the efficiency of your procedures. You must be capable to obtain an optimal product without putting your donor/patient at risk. Not only the total blood volume (TBV) of the donor/patient plays an important role, but also specific blood values influence the apheresis procedure. Therefore, not all donors/patients should be addressed in the same way. Calculation of TBV, extracorporeal volume, and total plasma volume is needed. Many issues determine your procedure time. By knowing the collection efficiency (CE) of your apheresis machine, you can calculate the number of blood volumes to be processed to obtain specific results. You can calculate whether you need one procedure to obtain specific results or more. It's not always needed to process 3× the TBV. In this way, it can be avoided that the donor/patient is needless long connected to the apheresis device. By calculating the CE of each device, you can also compare the various devices for quality control reasons, but also nurses/operators. PMID:25041907
NASA Astrophysics Data System (ADS)
von Woedtke, Th.; Reuter, S.; Masur, K.; Weltmann, K.-D.
2013-09-01
Plasma medicine is an innovative and emerging field combining plasma physics, life science and clinical medicine. In a more general perspective, medical application of physical plasma can be subdivided into two principal approaches. (i) “Indirect” use of plasma-based or plasma-supplemented techniques to treat surfaces, materials or devices to realize specific qualities for subsequent special medical applications, and (ii) application of physical plasma on or in the human (or animal) body to realize therapeutic effects based on direct interaction of plasma with living tissue. The field of plasma applications for the treatment of medical materials or devices is intensively researched and partially well established for several years. However, plasma medicine in the sense of its actual definition as a new field of research focuses on the use of plasma technology in the treatment of living cells, tissues, and organs. Therefore, the aim of the new research field of plasma medicine is the exploitation of a much more differentiated interaction of specific plasma components with specific structural as well as functional elements or functionalities of living cells. This interaction can possibly lead either to stimulation or inhibition of cellular function and be finally used for therapeutic purposes. During recent years a broad spectrum of different plasma sources with various names dedicated for biomedical applications has been reported. So far, research activities were mainly focused on barrier discharges and plasma jets working at atmospheric pressure. Most efforts to realize plasma application directly on or in the human (or animal) body for medical purposes is concentrated on the broad field of dermatology including wound healing, but also includes cancer treatment, endoscopy, or dentistry. Despite the fact that the field of plasma medicine is very young and until now mostly in an empirical stage of development yet, there are first indicators of its enormous
The plasma environment of comets
Gombosi, T.I. )
1991-01-01
U.S. research activities in the area of cometary plasma physics during 1987-1990 are reviewed. Consideration is given to mass loading and its consequences in the upstream region, the cometary shock, the cometosheath, the diamagnetic cavity boundary and the inner shock, and the plasma tail. Special attention is given to models and observations that have modified the pre-encounter understanding of cometary plasma environments. 211 refs.
Energy Science and Technology Software Center (ESTSC)
2000-05-22
This software calculates a Wet Bulb Globe Temperature (WBGT) using standard measurements from a meteorological station. WBGT is used by Industrial Hygenists (IH) to determine heat stress potential to outdoor workers. Through the mid 1990''s, SRS technicians were dispatched several times daily to measure WBGT with a custom hand held instrument and results were dessiminated via telephone. Due to workforce reductions, the WSRC IH Department asked for the development of an automated method to simulatemore » the WBGT measurement using existing real time data from the Atmospheric Technologies Group''s meteorological monitoring network.« less
Hunter, Charles H.
2000-05-22
This software calculates a Wet Bulb Globe Temperature (WBGT) using standard measurements from a meteorological station. WBGT is used by Industrial Hygenists (IH) to determine heat stress potential to outdoor workers. Through the mid 1990''s, SRS technicians were dispatched several times daily to measure WBGT with a custom hand held instrument and results were dessiminated via telephone. Due to workforce reductions, the WSRC IH Department asked for the development of an automated method to simulate the WBGT measurement using existing real time data from the Atmospheric Technologies Group''s meteorological monitoring network.
Electric Calculators; Business Education: 7718.06.
ERIC Educational Resources Information Center
McShane, Jane
The course was developed to instruct students in the use of mechanical and/or electronic printing calculators, electronic display calculators, and rotary calculators to solve special business problems with occupational proficiency. Included in the document are a list of performance objectives, a course content outline, suggested learning…
10 CFR 766.102 - Calculation methodology.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Calculation methodology. 766.102 Section 766.102 Energy... ASSESSMENT OF DOMESTIC UTILITIES Procedures for Special Assessment § 766.102 Calculation methodology. (a) Calculation of Domestic Utilities' Annual Assessment Ratio to the Fund. Domestic utilities shall be...
46 CFR 172.225 - Calculations.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 7 2010-10-01 2010-10-01 false Calculations. 172.225 Section 172.225 Shipping COAST... BULK CARGOES Special Rules Pertaining to Great Lakes Dry Bulk Cargo Vessels § 172.225 Calculations. (a) Each vessel must be shown by design calculations to meet the survival conditions in § 172.245 in...
Decimals, Denominators, Demons, Calculators, and Connections
ERIC Educational Resources Information Center
Sparrow, Len; Swan, Paul
2005-01-01
The authors provide activities for overcoming some fraction misconceptions using calculators specially designed for learners in primary years. The writers advocate use of the calculator as a way to engage children in thinking about mathematics. By engaging with a calculator as part of mathematics learning, children are learning about and using the…
NASA Astrophysics Data System (ADS)
Cayzac, W.; Bagnoud, V.; Basko, M. M.; Blažević, A.; Frank, A.; Gericke, D. O.; Hallo, L.; Malka, G.; Ortner, A.; Tauschwitz, An.; Vorberger, J.; Roth, M.
2015-11-01
The energy loss of light ions in dense plasmas is investigated with special focus on low to medium projectile energies, i.e., at velocities where the maximum of the stopping power occurs. In this region, exceptionally large theoretical uncertainties remain and no conclusive experimental data are available. We perform simulations of beam-plasma configurations well suited for an experimental test of ion energy loss in highly ionized, laser-generated carbon plasmas. The plasma parameters are extracted from two-dimensional hydrodynamic simulations, and a Monte Carlo calculation of the charge-state distribution of the projectile ion beam determines the dynamics of the ion charge state over the whole plasma profile. We show that the discrepancies in the energy loss predicted by different theoretical models are as high as 20-30%, making these theories well distinguishable in suitable experiments.
Propagation of an atmospheric pressure plasma plume
Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.
2009-02-15
The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.
NASA Astrophysics Data System (ADS)
Sosedkin, A. P.; Lotov, K. V.
2016-09-01
LCODE is a freely distributed quasistatic 2D3V code for simulating plasma wakefield acceleration, mainly specialized at resource-efficient studies of long-term propagation of ultrarelativistic particle beams in plasmas. The beam is modeled with fully relativistic macro-particles in a simulation window copropagating with the light velocity; the plasma can be simulated with either kinetic or fluid model. Several techniques are used to obtain exceptional numerical stability and precision while maintaining high resource efficiency, enabling LCODE to simulate the evolution of long particle beams over long propagation distances even on a laptop. A recent upgrade enabled LCODE to perform the calculations in parallel. A pipeline of several LCODE processes communicating via MPI (Message-Passing Interface) is capable of executing multiple consecutive time steps of the simulation in a single pass. This approach can speed up the calculations by hundreds of times.
Wilde, B.H.; Fernandez, J.C.; Hsing, W.W.; Cobble, J.A.; Delamater, N.D.; Krauser, W.J.; Lindman, E.L.; Failor, B.H.
1995-07-01
Special Nova hohlraums have been designed to simulate the plasma conditions calculated for various NIF hohlraum point designs. These hohlraums attempt to maximize the laser pathlength for parametric instability measurements. A toroidal-shaped hohlraum with a diameter of 3200 microns and a length of 1600 microns allows a laser pathlength of about 2 mm. Filling the hohlraum with 1 atmosphere of neopentane gas gives an electron temperature of 3 keV and electron density near 0.1 of critical. Detailed LASNEX calculations for these hohlraums and comparisons to the NIF point design will be presented. Comparisons between data and calculations that characterize the plasma conditions (electron, radiation, and ion temperatures, electron density, etc) in these Nova hohlraums will also be shown.
Horton, W.; Hu, G.
1998-07-01
The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.
75 FR 66743 - Office of Special Education and Rehabilitative Services; List of Correspondence
Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-29
... Office of Special Education and Rehabilitative Services; List of Correspondence AGENCY: Department of... State Directors of Special Education Executive Director Bill East, reiterating that the calculation of State financial support for special education and related services for children with...
Slide Rule For Calculating Curing Schedules
NASA Technical Reports Server (NTRS)
Heater, Don
1995-01-01
Special-purpose slide rule devised for calculating schedules for storing and curing adhesives, sealants, and other materials characterized by known curing times and shelf lives. Prevents mistakes commonly made in determining storage and curing schedules.
ERIC Educational Resources Information Center
Paul, James; French, Peter; Cranston-Gingras, Ann
2001-01-01
Discussion of ethics in special education focuses on four challenges: (1) examination of special education's history within an ethical framework; (2) articulation of character morality as well as choice morality in special education ethical dilemmas; (3) examination of special education in a liberal democracy; and (4) development of an ethical…
ERIC Educational Resources Information Center
Kim, Byung Ha, Ed.; Yeo, Kwang Eung
The text on special education in Korea is divided into four major sections--a brief history of special education in Korea, the present status of special education in Korea, the special education plan of the Young Kwang Educational Foundation, and directory of schools and classes for the exceptional in Korea. Topics covered include the following:…
Foster, J.S. Jr.
1958-03-11
This patent describes apparatus for producing an electricity neutral ionized gas discharge, termed a plasma, substantially free from contamination with neutral gas particles. The plasma generator of the present invention comprises a plasma chamber wherein gas introduced into the chamber is ionized by a radiofrequency source. A magnetic field is used to focus the plasma in line with an exit. This magnetic field cooperates with a differential pressure created across the exit to draw a uniform and uncontaminated plasma from the plasma chamber.
Analysis of nuclear induced plasmas
NASA Technical Reports Server (NTRS)
Deese, J. E.; Hassan, H. A.
1976-01-01
A kinetic model is developed for a plasma generated by fission fragments, and the results are employed to study He plasma generated in a tube coated with fissionable material. Because both the heavy particles and electrons play important roles in creating the plasma, their effects are considered simultaneously. The calculations are carried out for a range of neutron fluxes and pressures. In general, the predictions of the theory are in good agreement with available intensity measurements. Moreover, the theory predicts the experimentally measured inversions. However, the calculated gain coefficients are such that lasing is not expected to take place in a helium plasma generated by fission fragments.
Wakes in Inertial Fusion Plasmas
NASA Astrophysics Data System (ADS)
Ellis, Ian Norman
Plasma wave wakes, which are the collective oscillatory response near the plasma frequency to the propagation of particles or electromagnetic waves through a plasma, play a critical role in many plasma processes. New results from backwards stimulated Raman scattering (BSRS), in which wakes with phase velocities much less than the speed of light are induced by the beating of counter-propagating light waves, and from electron beam stopping, in which the wakes are produced by the motion of relativistically propagating electrons through the dense plasma, are discussed. Both processes play important roles in Inertial Confinement Fusion (ICF). In BSRS, laser light is scattered backwards out of the plasma, decreasing the energy available to compress the ICF capsule and affecting the symmetry of where the laser energy hits the hohlraum wall in indirect drive ICF. The plasma wave wake can also generate superthermal electrons that can preheat the core and/or the ablator. Electron beam stopping plays a critical role in the Fast Ignition (FI) ICF concept, in which a beam of relativistic electrons is used to heat the target core to ignition temperatures after the compression stage. The beam stopping power determines the effectiveness of the heating process. This dissertation covers new discoveries on the importance of plasma wave wakes in both BSRS and electron beam stopping. In the SRS studies, 1D particle-in-cell (PIC) simulations using OSIRIS are performed, which model a short-duration (˜500/ω0 --1FWHM) counter-propagating scattered light seed pulse in the presence of a constant pump laser with an intensity far below the absolute instability threshold for plasma waves undergoing Landau damping. The seed undergoes linear convective Raman amplification and dominates over the amplification of fluctuations due to particle discreteness. The simulation results are in good agreement with results from a coupled-mode solver when special relativity and the effects of finite size PIC
EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets
NASA Astrophysics Data System (ADS)
Kong, M. G.; Ganguly, B. N.; Hicks, R. F.
2012-06-01
-mentioned early studies has witnessed a considerable and exciting growth in terms of new phenomena observed, new physics and chemistry uncovered, new plasma jet sources conceived, and new applications developed. Examples include the observations of plasma bullets on a nanosecond scale [16], the similarity of plasma bullets to streamers [17], arrays of plasma jets as metamaterials [18], and a rapid increase of applications in biomedicine [19]. However the considerable growth in the research of plasma jets has not been adequately supported, so far, by a sound fundamental underpinning, partly resulting from a somewhat underdevelopment of effective diagnostics and modelling tools. Recognizing the critical importance of basic science for future growth of low-temperature plasma jet technology, this special issue on plasma jets and bullets aims to address some of the most important fundamental questions. Many of the special issue papers continue the established line of investigation to characterize the formation of plasma bullets, using typically ultrafast imaging, electrical detection including electric field and plasma conductivity measurement, and optical emission spectrometry [20]-[26]. These offer strong experimental evidence for the well-known hypothesis that a plasma jet is a form of streamer, and that the ionization wave plays a critical role in their formation. The interaction of two parallel plasma jets [27] and manipulation of plasma jet characteristics [28, 29] are also reported using a similar combination of experimental techniques. Some of the common characteristics of plasma jets are summarized in a review paper in this special issue [30]. A somewhat different line of investigation is employed in a detailed experimental characterization of deterministic chaos in atmospheric plasma jets [31], one of the few non-bullet modes of plasma jets. Although chaos in ionized gases have been observed in other types of discharge plasmas, their applications have not so far been linked
Nuclear Material Variance Calculation
Energy Science and Technology Software Center (ESTSC)
1995-01-01
MAVARIC (Materials Accounting VARIance Calculations) is a custom spreadsheet that significantly reduces the effort required to make the variance and covariance calculations needed to determine the detection sensitivity of a materials accounting system and loss of special nuclear material (SNM). The user is required to enter information into one of four data tables depending on the type of term in the materials balance (MB) equation. The four data tables correspond to input transfers, output transfers,more » and two types of inventory terms, one for nondestructive assay (NDA) measurements and one for measurements made by chemical analysis. Each data entry must contain an identification number and a short description, as well as values for the SNM concentration, the bulk mass (or solution volume), the measurement error standard deviations, and the number of measurements during an accounting period. The user must also specify the type of error model (additive or multiplicative) associated with each measurement, and possible correlations between transfer terms. Predefined spreadsheet macros are used to perform the variance and covariance calculations for each term based on the corresponding set of entries. MAVARIC has been used for sensitivity studies of chemical separation facilities, fuel processing and fabrication facilities, and gas centrifuge and laser isotope enrichment facilities.« less
Quantitative diagnostics of reactive, multicomponent low-temperature plasmas
NASA Astrophysics Data System (ADS)
Schwarz-Selinger, Thomas
2013-09-01
The special emphasis in this work is put on the quantitative determination of the plasma composition of an inductively coupled low temperature plasma (ICP). Several standard plasma diagnostic techniques were applied. As a test case for a multi-component low-temperature plasma argon-hydrogen as well as argon-hydrogen-nitrogen mixed plasmas were investigated. For steady-state plasma operation the ion density and electron temperature were determined with a single tip Langmuir probe. A multi-grid miniature retarding-field analyzer was used to measure the mass integrated ion flux. An energy-dispersive mass spectrometer - a so-called plasma monitor (PM) - was applied to sample ions from the plasma to derive the ion composition. The degree of dissociation of hydrogen and the gas temperature were derived from optical emission spectroscopy. The gas temperature was estimated by the rotational distribution of the Q-branch lines of the hydrogen Fulcher- α diagonal band for the argon-hydrogen mixed plasmas and from the second positive system of N2 in argon-hydrogen-nitrogen mixed plasmas. The degree of dissociation of hydrogen was measured by actinometry. The influence of the substrate material of the counter electrode (stainless steel, copper, tungsten, Macor, and aluminium) on the atomic hydrogen concentration was investigated by OES. In addition, ionization-threshold mass spectrometry (ITMS) was used to determine the densities of atomic nitrogen (N) and atomic hydrogen (H and D). Pulsed plasma operation was applied to directly measure the loss rate of H, D and N in the afterglow from the temporal decay of the ITMS signal. From these data the wall loss probability of atomic hydrogen was determined. Furthermore, a zero-dimensional rate equation model was devised to explain the ion composition in these mixed plasmas with different admixture ratios. In addition to the experimental data on electron density, gas temperature, total pressure, atomic hydrogen density, and Ar, H2
NASA Astrophysics Data System (ADS)
Laroussi, M.; Kong, M. G.; Morfill, G.; Stolz, W.
2012-05-01
Foreword R. Satava and R. J. Barker; Part I. Introduction to Non-equilibrium Plasma, Cell Biology, and Contamination: 1. Introduction M. Laroussi; 2. Fundamentals of non-equilibrium plasmas M. Kushner and M. Kong; 3. Non-equilibrium plasma sources M. Laroussi and M. Kong; 4. Basic cell biology L. Greene and G. Shama; 5. Contamination G. Shama and B. Ahlfeld; Part II. Plasma Biology and Plasma Medicine: 6. Common healthcare challenges G. Isbary and W. Stolz; 7. Plasma decontamination of surfaces M. Kong and M. Laroussi; 8. Plasma decontamination of gases and liquids A. Fridman; 9. Plasma-cell interaction: prokaryotes M. Laroussi and M. Kong; 10. Plasma-cell interaction: eukaryotes G. Isbary, G. Morfill and W. Stolz; 11. Plasma based wound healing G. Isbary, G. Morfill and W. Stolz; 12. Plasma ablation, surgery, and dental applications K. Stalder, J. Woloszko, S. Kalghatgi, G. McCombs, M. Darby and M. Laroussi; Index.
Mississippi Special Olympics: Special Events Manual.
ERIC Educational Resources Information Center
Heinze, Toni; Cooper, Walter E.
Provided in the manual are organizational guidelines and suggested activities for a Special Evants segment of the Mississippi Special Olympics Program to encourage participation by low motor functioning, multihandicapped, mentally retarded persons. Information is provided concerning objectives, organizational set-up, guidelines, communication…
SPECIAL CLASSES FOR STUDENTS WITH SPECIAL NEEDS.
ERIC Educational Resources Information Center
DOWELL, G.L.
A SPECIAL 3-YEAR TRAINING PROGRAM IN FARM POWER AND MACHINERY WAS DEVELOPED TO PROVIDE FOR DIFFERENT LEVELS OF STUDENT ACHIEVEMENT AND TO HELP MEET THE NEED FOR SKILLED WORKERS IN THE MISSISSIPPI DELTA AREA. CHANGES IN THE LEARNING ENVIRONMENT OF STUDENTS TRANSFERRED FROM REGULAR VOCATIONAL AGRICULTURE CLASSES TO THE SPECIAL CLASSES PROVIDE A MORE…
Plasma generating apparatus for large area plasma processing
Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.
1991-07-16
A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.
Plasma generating apparatus for large area plasma processing
Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.
1991-01-01
A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.
... Alcohol Calorie Calculator Weekly Total 0 Calories Alcohol Calorie Calculator Find out the number of beer and ... Calories College Alcohol Policies Interactive Body Calculators Alcohol Calorie Calculator Alcohol Cost Calculator Alcohol BAC Calculator Alcohol ...
NASA Technical Reports Server (NTRS)
Harries, W. L.
1977-01-01
The possibility of creating a plasma from fission fragments was investigated, as well as the probability of utilizing the energy of these particles to create population inversion leading to laser action. Eventually, it is hoped that the same medium could be used for both fissioning and lasing, thus avoiding inefficiences in converting one form of energy to the other. A central problem in understanding a fission induced plasma is to obtain an accurate model of the electron behavior; some calculations are presented to this end. The calculations are simple, providing a compendium of processes for reference.
Cai Hongbo; Zhu Shaoping; Wu Sizhong; Chen Mo; Zhou Cangtao; He, X. T.; Yu Wei; Nagatomo, Hideo
2011-02-15
The efficient magnetic collimation of fast electron flow transporting in overdense plasmas is investigated with two-dimensional collisional particle-in-cell numerical simulations. It is found that the specially engineered targets exhibiting either high-resistivity-core-low-resistivity-cladding structure or low-density-core-high-density-cladding structure can collimate fast electrons. Two main mechanisms to generate collimating magnetic fields are found. In high-resistivity-core-low-resistivity-cladding structure targets, the magnetic field at the interfaces is generated by the gradients of the resistivity and fast electron current, while in low-density-core-high-density-cladding structure targets, the magnetic field is generated by the rapid changing of the flow velocity of the background electrons in transverse direction (perpendicular to the flow velocity) caused by the density jump. The dependences of the maximal magnetic field on the incident laser intensity and plasma density, which are studied by numerical simulations, are supported by our analytical calculations.
NASA Astrophysics Data System (ADS)
Polomarov, Oleg; Theodosiou, Constantine; Kaganovich, Igor
2003-10-01
A self-consistent system of equations for the kinetic description of non-local, non-uniform, nearly collisionless plasmas of low-pressure discharges is presented. The system consists of a non-local conductivity operator, and a kinetic equation for the electron distribution function (EEDF) averaged over fast electron bounce motions. A Fast Fourier Transform (FFT) method was applied to speed up the numerical simulations. The importance of accounting for the non-uniform plasma density profile in computing the current density profile and the EEDF is demonstrated. Effects of plasma non-uniformity on electron heating in rf electric field have also been studied. An enhancement of the electron heating due to the bounce resonance between the electron bounce motion and the rf electric field has been observed. Additional information on the subject is posted in http://www.pppl.gov/pub_report/2003/PPPL-3814-abs.html and in http://arxiv.org/abs/physics/0211009
Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators
Rittershofer, W.; Schroeder, C.B.; Esarey, E.; Gruner, F.J.; Leemans, W.P.
2010-05-17
Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal and transverse fields differ, and, hence, the required tapering differs. The length over which the tapered plasma density becomes singular is calculated. Linear plasma tapering as well as discontinuous plasma tapering, which moves beams to adjacent plasma wave buckets, are also considered. The energy gain of an accelerated electron in a tapered laser-plasma accelerator is calculated and the laser pulse length to optimize the energy gain is determined.
Laboratory photoionized plasma experiments at Z - Comparison with modeling
NASA Astrophysics Data System (ADS)
Mayes, D.; Lockard, T.; Durmaz, T.; Hall, I.; Mancini, R.; Bailey, J.; Rochau, G.; Loisel, G.; Heeter, R.; Liedahl, D.
2013-10-01
Photoionized plasmas are common in astrophysical environments, such as x-ray binaries and active galactic nuclei. We discuss an experimental and modeling effort to study the atomic kinetics in plasmas of this type via K-shell line absorption spectroscopy. Results from a first pass thru our 2nd-generation dataset are compared with results of several modeling codes attempting to simulate our experimental conditions. The experiment employs the intense x-ray flux emitted by the collapse of a z-pinch to produce and backlight a Neon photoionized plasma in a cm-scale gas cell at various distances from the z-pinch. The filling pressure is monitored in situ providing the plasma particle number density. High-resolution spectra from a TREX spectrometer are processed with a suite of specially designed IDL tools to produce transmission spectra, which show absorption in several ionization stages of Neon. Analysis independent of atomic kinetics calculations yields the charge state distribution and ion areal densities used to benchmark atomic kinetics codes. In addition, the electron temperature, extracted from a level population ratio, is used to test heating models. This work is sponsored in part by the National Nuclear Security Administration under the High Energy Density Laboratory Plasmas grant program through DOE Grant DE-FG52-09NA29551, and the Z Facility Fundamental Science Program of SNL.
NASA Astrophysics Data System (ADS)
Riemann, Karl-Ulrich
2012-10-01
In typical gas discharges a quasineutral plasma is shielded from a negativ absorbing wall by a thin positive sheath that is nearly planar and collision-free. The subdivision of ``plasma'' and ``sheath'' was introduced by Langmuir and is based on a small ratio of the electron Debye lenghth λD to the dominant competing characteristic plasma length l. Depending on the special conditions, l may represent, e.g., the plasma extension, the ionization length, the ion mean free path, the ion gyro radius, or a geometric length. Strictly speaking, this subdivion is possible only in the asymptotic limit λD/l->0. The asymptotic analysis results in singularities at the ``sheath edge'' closely related to the ``Bohm criterion.'' Due to these singularities a direct smooth matching of the separate plasma and sheath soltions is not possible. To obtain a consistent smooth transition, the singular sheath edge must be bridged by an additinal narrow ``intermediate'' model zone accounting both for plasma processes (e.g., collisions) and for the first build up of space charge. Due to this complexity and to different interpretations of the ``classical'' papers by Langmuir and Bohm, the asymptotic plasma-sheath concept and the definition of the sheath edge were questioned and resulted in controversies during the last two decades. We discuss attempts to re-define the sheath edge, to account for finite values of λD/l in the Bohm criterion, and demonstrate the consistent matching of plasma and sheath. The investigations of the plasma-sheath transition discussed so far are based on a simplified fluid analysis that cannot account for the essential inhomogeneity of the boundary layer and for the dominant role of slow ions in space charge formation. Therefore we give special emphasis to the kinetic theory of the plasma-sheath transition. Unfortunately this approach results in an additional mathematical difficulty caused by ions with zero velocity. We discuss attempts to avoid this singularity by
PREFACE: Special issue: CAMOP-MOLEC XVII Special issue: CAMOP-MOLEC XVII
NASA Astrophysics Data System (ADS)
Vasyutinskii, Oleg
2009-10-01
This special issue of CAMOP/Physica Scripta presents highlights from the scientific contributions presented at the European Conference on Dynamics of Molecular Systems (MOLEC XVII) held on 23-29 August 2008 at St Petersburg, Russia. This meeting was the seventeenth in a series of biannual meetings that started in 1976, when the first conference was held in Trento, Italy. Subsequent meetings were held at Brandbjerg Hojskole (Denmark), Oxford (UK), Nijmegen (The Netherlands), Jerusalem (Israel), Aussois (France), Assisi (Italy), Bernkastel-Kues (Germany), Prague (Czech Republic), Salamanca (Spain), Nyborg Strand (Denmark), Bristol (UK), Jerusalem (Israel), Istanbul (Turkey), Nunspeet (The Netherlands) and Trento (Italy). In 2008, the meeting was jointly organized by scientists from the Ioffe Institute, Russian Academy of Sciences, St Petersburg, Herzen State University, St Petersburg, Moscow State University, St Petersburg Polytechnical University, and St Petersburg State University. About 150 scientists from 21 countries visited Pushkin, a beautiful suburb of St Petersburg near the famous palace of Empress Catherine II, and discussed the state of the art and trends in the field, as well as new methods and applications, during 24 plenary lectures, 36 hot topic talks and two evening poster sessions. A special event was the presentation of the MOLEC XVII award to Professor Grabriel Balint-Kurti for his outstanding contributions to the theory of reaction dynamics and molecular photodissociation. Further information is available from the homepage of the meeting: http://www.ioffe.ru/MOLEC17/. This special issue covers different aspects of atomic and molecular interactions, with emphasis on both experimental and theoretical studies of the dynamics of elastic, inelastic and reactive encounters between atoms, molecules, ions, clusters and surfaces. More specifically, it includes molecular collisions in different environments; plasma, atmospheric, interstellar and combustion
Surface currents on ideal plasmas
Webster, Anthony J.
2010-11-15
The surface (or 'skin') current that can flow at a perturbed interface between plasma and vacuum is considered in the approximation where a surface marks a sharp transition from plasma to vacuum. A short magnetohydrodynamic calculation gives an exact and general expression for the component perpendicular to the average of the magnetic field either side of the surface, finding it proportional to the edge plasma pressure. A consequence is that for all plasmas with zero surface current at equilibrium, the surface current associated with any linear instability will flow parallel to the magnetic field. The surface current is calculated for a simple but realistic model of a cylindrical plasma, and found to depend on the type of instability, and consequently on the particular plasma equilibrium. This is illustrated for two well known cases.
ERIC Educational Resources Information Center
Abang, Theresa B.
1992-01-01
This article discusses the special education system in Nigeria, focusing on integration; training of special educators; medical, health, and welfare services for children with disabilities; recreational facilities; employment opportunities; national planning; and problems and successes. (JDD)
Algorithmically specialized parallel computers
Snyder, L.; Jamieson, L.H.; Gannon, D.B.; Siegel, H.J.
1985-01-01
This book is based on a workshop which dealt with array processors. Topics considered include algorithmic specialization using VLSI, innovative architectures, signal processing, speech recognition, image processing, specialized architectures for numerical computations, and general-purpose computers.
Codes with special correlation.
NASA Technical Reports Server (NTRS)
Baumert, L. D.
1964-01-01
Uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets uniform binary codes with special correlation including transorthogonality and simplex code, Hadamard matrices and difference sets
46 CFR 174.360 - Calculations.
Code of Federal Regulations, 2010 CFR
2010-10-01
..., as amended, chapter II-1, part B-1. 46 CFR Ch. I (10-1-10 Edition) Coast Guard, DHS ... 46 Shipping 7 2010-10-01 2010-10-01 false Calculations. 174.360 Section 174.360 Shipping COAST... SPECIFIC VESSEL TYPES Special Rules Pertaining to Dry Cargo Ships § 174.360 Calculations. Each ship...
Mentorship of Special Educators
ERIC Educational Resources Information Center
Madigan, Jennifer Booker; Schroth-Cavataio, Georganne
2012-01-01
The national shortage and exceptionally high attrition rate of special education teachers are impediments to serving students with special needs. Given that only 64 percent of special education teachers have access to a mentor compared with 86 percent of general education teachers, this book meets an essential need for attracting, retaining, and…
Special Effects Activity Guide.
ERIC Educational Resources Information Center
Boxer, Jennifer; Valenta, Carol
This guide accompanies "Special Effects," a 40-minute IMAX film and "Special Effects II", a multimedia, interactive traveling exhibit designed by the California Museum of Science and Industry. The exhibit focuses on the underlying scientific and technical processes of special effects from the earliest motion picture to state-of-the-art digital…
ERIC Educational Resources Information Center
Whitfield, Keith E.; Edwards, Christopher L.
2011-01-01
Mentorship is critical for career development. Members of special populations are at increased risk of information shortfalls and advice that is not framed with cultural sensitivity. Special knowledge and skills are needed to successfully mentor members of ethnic minority and other special populations. Midlevel and senior scientists need…
Assessing Special Educational Needs.
ERIC Educational Resources Information Center
Wolfendale, Sheila, Ed.
This essays in this book contain valuable and up-to-date information about current issues and developments in assessing special educational needs. The context of the book is the mainstream setting in the United Kingdom. The aim of these chapters is to consider special needs in inclusive education, consistent with British special needs legislation.…
Modelling the Plasma Jet in Multi-Arc Plasma Spraying
NASA Astrophysics Data System (ADS)
Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.
2016-08-01
Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.
Conductivity of a relativistic plasma
Braams, B.J.; Karney, C.F.F.
1989-03-01
The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.
Lysosomes and the plasma membrane
Andrews, Norma W.
2002-01-01
Studies of the cell invasion mechanism of the parasite Trypanosoma cruzi led to a series of novel findings, which revealed a previously unsuspected ability of conventional lysosomes to fuse with the plasma membrane. This regulated exocytic process, previously regarded mostly as a specialization of certain cell types, was recently shown to play an important role in the mechanism by which cells reseal their plasma membrane after injury. PMID:12147679
Special issue: diagnostics of atmospheric pressure microplasmas
NASA Astrophysics Data System (ADS)
Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide
2013-11-01
In recent decades, a strong revival of non-equilibrium atmospheric pressure plasma studies has developed in the form of microplasmas. Microplasmas have typical scales of 1 mm or less and offer a very exciting research direction in the field of plasma science and technology as the discharge physics can be considerably different due to high collisionality and the importance of plasma-surface interaction. These high-pressure small-scale plasmas have a diverse range of physical and chemical properties. This diversity coincides with various applications including light/UV sources [1], material processing [2], chemical analysis [3], material synthesis [4], electromagnetics [5], combustion [6] and even medicine [7]. At atmospheric pressure, large scale plasmas have the tendency to become unstable due to the high collision rates leading to enhanced heating and ionization compared to their low-pressure counterparts. As low-pressure plasmas typically operate in reactors with sizes of tens of centimetres, scaling up the pressure to atmospheric pressure the size of the plasma reduces to typical sizes below 1 mm. A natural approach of stabilizing atmospheric pressure plasmas is thus the use of microelectrode geometries. Traditionally microplasmas have been produced in confined geometries which allow one to stabilize dc excited discharges. This stabilization is intrinsically connected to the large surface-to-volume ratio which enhances heat transfer and losses of charged and excited species to the walls. Currently challenging boundaries are pushed by producing microcavity geometries with dimensions of the order of 1 µm [8]. The subject of this special issue, diagnostics of microplasmas, is motivated by the many challenges in microplasma diagnostics in view of the complex chemistry and strong spatial (and even temporal) gradients of species densities and plasma properties. Atmospheric pressure plasmas have a very long history dating back more than 100 years, with early work of
Io Plasma Torus: Nature of the Iogenic Plasma Source
NASA Astrophysics Data System (ADS)
Marconi, M. L.; Smyth, W. H.
1996-09-01
The primary source of plasma for Jupiter's magnetosphere is supplied internally by Io, the innermost Galilean satellite. The Iogenic plasma source is created by gases (e.g., Na, K, O, S, and SO_2) lost from Io as they undergo electron impact and charge exchange reactions in the plasma torus. This Iogenic plasma source provides mass, momentum, pick-up electrical conductivity, and energy to the plasma torus. The three-dimensional nature of the Iogenic plasma source is an important input quantity (1) in local studies to understand the plasma torus properties (density, composition, subcorotational motion, electric currents, and temperature) and the plasma torus near-Io MHD flow and atmosphere interactions, and (2) in more global studies to understand the spacetime structure of the outward transport dynamics of the plasma torus, such as in RCM-J (Rice Convection Model for Jupiter) calculations. To elucidate and quantify the nature of the Iogenic plasma source for such studies, we have undertaken simulations of it using the AER neutral cloud models. Calculations will be presented to illustrate the spacetime nature of the Iogenic plasma source and to estimate the net-mass, momentum and energy input rates to the plasma torus and the height-integrated electrical conductivity near Io and in Jupiter's ionosphere. These calculations show that the instantaneous Iogenic plasma source is highly peaked at Io's position in the plasma torus and that its rates vary significantly with Io System III longitude and also with Io phase angle because of the east-west electric field. For the lower-velocity escape of gases by incomplete collisional cascade processes (i.e., plasma torus ion sputtering), contributions to the instantaneous Iogenic plasma source are primarily confined to a broader (but still limited) spatial region in L-shell and System III longitude angle near Io. For the higher-velocity loss of gases by charge exchange, contributions to the Iogenic plasma source are more
Wakes in inhomogeneous plasmas.
Kompaneets, Roman; Ivlev, Alexei V; Nosenko, Vladimir; Morfill, Gregor E
2014-04-01
The Debye shielding of a charge immersed in a flowing plasma is an old classic problem. It has been given renewed attention in the last two decades in view of experiments with complex plasmas, where charged dust particles are often levitated in a region with strong ion flow. Efforts to describe the shielding of the dust particles in such conditions have been focused on the homogeneous plasma approximation, which ignores the substantial inhomogeneity of the levitation region. We address the role of the plasma inhomogeneity by rigorously calculating the point charge potential in the collisionless Bohm sheath. We demonstrate that the inhomogeneity can dramatically modify the wake, making it nonoscillatory and weaker. PMID:24827356
General very special relativity in Finsler cosmology
Kouretsis, A. P.; Stathakopoulos, M.; Stavrinos, P. C.
2009-05-15
General very special relativity (GVSR) is the curved space-time of very special relativity (VSR) proposed by Cohen and Glashow. The geometry of general very special relativity possesses a line element of Finsler geometry introduced by Bogoslovsky. We calculate the Einstein field equations and derive a modified Friedmann-Robertson-Walker cosmology for an osculating Riemannian space. The Friedmann equation of motion leads to an explanation of the cosmological acceleration in terms of an alternative non-Lorentz invariant theory. A first order approach for a primordial-spurionic vector field introduced into the metric gives back an estimation of the energy evolution and inflation.
Plasma stabilization experiment
NASA Astrophysics Data System (ADS)
Sziklas, E. A.; Fader, W. J.; Jong, R. A.; Stufflebeam, J. H.
1980-07-01
The plasma stabilization experiment is an effort to enhance stability in a mirror-confined plasma by trapping cold ions with rf fields applied near the mirror throats. Nagoya Type 3 antennas, coupled to a 60 kW rf power supply are mounted in the throats of the UTRC baseball magnet. An external washer gun provides a source of plasma for both streaming and confined plasma tests. Results show a strong stoppering effect on streaming plasmas and a marginal effect on confined plasmas. Theoretical calculations provide an explanation for the experimental observations. The field generates a ponderomotive force acting on the electrons. The resultant improvement in electron confinement changes the ambipolar potential and inhibits the flow of ions through the mirror throat. Criteria are derived for the validity of this trapping concept. The requisite field strengths are significantly lower than those required to trap ions directly. Scaling laws are developed for application of cold ion trapping to large mirror devices containing dense plasmas. The use of slow-wave antenna structures operated at frequencies above the lower hybrid frequency is recommended for these applications.
Mathematical and computational models of plasma flows
NASA Astrophysics Data System (ADS)
Brushlinsky, K. V.
Investigations of plasma flows are of interest, firstly, due to numerous applications, and secondly, because of their general principles, which form a special branch of physics: the plasma dynamics. Numerical simulation and computation, together with theoretic and experimental methods, play an important part in these investigations. Speaking on flows, a relatively dense plasma is mentioned, so its mathematical models appertain to the fluid mechanics, i.e., they are based on the magnetohydrodynamic description of plasma. Time dependent two dimensional models of plasma flows of two wide-spread types are considered: the flows across the magnetic field and those in the magnetic field plane.