WorldWideScience

Sample records for nonneutral plasma column

  1. Finite-Length Diocotron Modes in a Non-neutral Plasma Column

    Science.gov (United States)

    Walsh, Daniel; Dubin, Daniel

    2017-10-01

    Diocotron modes are 2D distortions of a non-neutral plasma column that propagate azimuthally via E × B drifts. While the infinite-length theory of diocotron modes is well-understood for arbitrary azimuthal mode number l, the finite-length mode frequency is less developed (with some exceptions), and is naturally of relevance to experiments. In this poster, we present an approach to address finite length effects, such as temperature dependence of the mode frequency. We use a bounce-averaged solution to the Vlasov Equation, in which the Vlasov Equation is solved using action-angle variables of the unperturbed Hamiltonian. We write the distribution function as a Fourier series in the bounce-angle variable ψ, keeping only the bounce-averaged term. We demonstrate a numerical solution to this equation for a realistic plasma with a finite Debye Length, compare to the existing l = 1 theory, and discuss possible extensions of the existing theory to l ≠ 1 . Supported by NSF/DOE Partnership Grants PHY1414570 and DESC0002451.

  2. Modes in a nonneutral plasma column of finite length

    International Nuclear Information System (INIS)

    Rasband, S. Neil; Spencer, Ross L.

    2002-01-01

    A Galerkin, finite-element, nonuniform mesh computation of the mode equation for waves in a non-neutral plasma of finite length in a Cold-Fluid model gives an accurate calculation of the mode eigenfrequencies and eigenfunctions. We report on studies of the following: (1) finite-length Trivelpiece-Gould modes with flat-top and realistic density profiles, (2) finite-length diocotron modes with flat density profiles. We compare with the frequency equation of Fine and Driscoll [Phys Plasmas 5, 601 (1998)

  3. Transport of a nonneutral electron plasma due to electron collisions with neutral atoms

    International Nuclear Information System (INIS)

    Douglas, M.H.; O'Neil, T.M.

    1978-01-01

    Transport of a nonneutral electron plasma across a magnetic field is caused by electron scattering from ambient neutral atoms. A theoretical model of such transport is presented, assuming the plasma is quiescent and the scattering is elastic scattering from infinite mass scattering centers of constant momentum transfer cross section. This model is motivated by recent experiments. A reduced transport equation is obtained by expanding the Boltzmann equation for the electron distribution in inverse powers of the magnetic field. The equation together with Poisson's equation for the radial electric field, which must exist in a nonneutral column, determine the evolution of the system. When these two equations are properly scaled, they contain only a single parameter: the ratio of initial Debye length to initial column radius. For cases where this parameter is either large or small, analytical solutions, or at least partial solutions, are obtained. For intermediate values of the parameter, numerical solutions are obtained

  4. Bernstein modes in a non-neutral plasma column

    Science.gov (United States)

    Walsh, Daniel; Dubin, Daniel H. E.

    2018-05-01

    This paper presents theory and numerical calculations of electrostatic Bernstein modes in an inhomogeneous cylindrical plasma column. These modes rely on finite Larmor radius effects to propagate radially across the column until they are reflected when their frequency matches the upper hybrid frequency. This reflection sets up an internal normal mode on the column and also mode-couples 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, are presented and compared to an analytical Wentzel Kramers Brillouin (WKB) theory. A previous version of the theory [D. H. E. Dubin, Phys. Plasmas 20(4), 042120 (2013)] expanded the plasma response in powers of 1/B, approximating the local upper hybrid frequency, and consequently, its frequency predictions are spuriously shifted with respect to the numerical results presented here. A new version of the WKB theory avoids this approximation using the exact cold fluid plasma response and does a better job of reproducing the numerical frequency spectrum. The effect of multiple ion species on the mode spectrum is also considered, to make contact with experiments that observe cyclotron modes in a multi-species pure ion plasma [M. Affolter et al., Phys. Plasmas 22(5), 055701 (2015)].

  5. Toroidal magnetic confinement of non-neutral plasmas

    International Nuclear Information System (INIS)

    Yoshida, Zensho; Ogawa, Yuichi; Morikawa, Junji; Himura, Haruhiko; Kondo, Shigeo; Nakashima, Chihiro; Kakuno, Shuichi; Iqbal, Muhamad; Volponi, Francesco; Shibayama, Norihisa; Tahara, Shigeru

    1999-01-01

    A new method of toroidal non-neutral plasma trap has been developed with applying the chaos-induced radial transport of particles near a magnetic null point. A pure electron plasma is produced by injecting an electron beam. The poloidal gyroradius of an electron at the energy of 1 keV is of order 10 mm, which determines the length scale of the chaotic region. Amongst various applications of toroidal non-neutral plasmas, a possibility of producing very high-β plasma, which is suitable for advanced fusion, has been examined. The self-electric field of a non-neutral plasma can generate a strong shear flow. When the flow velocity is comparable to the Alfven speed (which is smaller than the ion sound speed, if β>1), a high-β equilibrium can be produced in which the plasma pressure is primarily balanced by the dynamic pressure of the flow. This configuration is described by a generalized Bernoulli law

  6. Galaxies and Saturn's rings: Gravitational analogues of nonneutral plasmas

    International Nuclear Information System (INIS)

    Mark, J.W.K.

    1985-01-01

    Orbit and collective dynamics in disk galaxies and in Saturn's rings are gravitational analogues of those occurring in nonneutral plasmas. The interesting problems for such ''gravitational plasmas'' are analogous to single-disk studies of transverse dynamics in particle beams. Of particular interest are various orbit-resonances with spiral density and bending waves in these disks which are analogous to electrostatic waves in nonneutral beam plasmas. The background physics, terminology and results of astrophysical investigations in these fields are surveyed in this paper. 53 refs., 19 figs., 1 tab

  7. 2D Diffusion of Rods in a Nonneutral Plasma with Finite E × B Shear.

    Science.gov (United States)

    Jin, D. Z.; Dubin, Daniel H. E.

    2000-10-01

    Cross-magnetic-field collisional diffusion of test particles is discussed for a nonneutral plasma column in the 2D regime, where the diffusion is due to the E × B drift of charged rods (bounce-averaged electrons) in the random Coulomb fields of other rods. If the overall flow has a finite E × B velocity shear, the diffusion can be orders of magnitude smaller than predicted by previous calculations,(J.B. Taylor and B. McNamara, Phys. Fluids 14), 1492 (1971); J.M. Dawson, H. Okuda and R.N. Carlile, Phys. Rev. Lett. 27, 491 (1971). which are shown to hold only for a nearly shear-free plasma. Particle-in-cell and molecular dynamics simulations of the diffusion match the theory, provided that the E × B rotation frequency is monotonically decreasing as a function of radius (negative shear, the usual case in a stable nonneutral plasma column). Interestingly, when the rotation frequency is monotonically increasing (positive shear), the transport is suppressed by another order of magnitude or more. This phenomenon is related to the nonlinear dynamics of prograde point vortices in a shear flow.(David A. Schecter and Daniel H.E. Dubin, Phys. Rev. Lett. 83), 2191 (1999).

  8. Experiments on Plasma Physics : Experience is the Mother of Wisdom 5.What We Expect with Nonneutral Plasmas

    Science.gov (United States)

    Kiwamoto, Yasuhito

    The present status of nonneutral plasma science is reviewed with a particular interest in the pursuit of a new frontier for plasma physicists engaged in basic researches. The author does not intend to be exhaustive nor well balanced in the description, but tries to discuss where we are positioned and what we might be able to do to fruitfully enjoy plasma physics and extend its field of activity. Leaving most of topics to the cited references, the author describes characteristic features of nonneutral plasmas appearing in distinct confinement properties, equilibria, transport, nonlinear evolution of Kelvin-Helmholtz instability, and fluid echo phenomena. These examples may convey the significance of nonneutral plasma science as one of newly-rising branches of plasma physics and as a potentially relevant channel through which plasma physics could explore new dimensions.

  9. Oblique non-neutral solitary Alfven modes in weakly nonlinear pair plasmas

    International Nuclear Information System (INIS)

    Verheest, Frank; Lakhina, G S

    2005-01-01

    The equal charge-to-mass ratio for both species in pair plasmas induces a decoupling of the linear eigenmodes between waves that are charge neutral or non-neutral, also at oblique propagation with respect to a static magnetic field. While the charge-neutral linear modes have been studied in greater detail, including their weakly and strongly nonlinear counterparts, the non-neutral mode has received less attention. Here the nonlinear evolution of a solitary non-neutral mode at oblique propagation is investigated in an electron-positron plasma. Employing the framework of reductive perturbation analysis, a modified Korteweg-de Vries equation (with cubic nonlinearity) for the lowest-order wave magnetic field is obtained. In the linear approximation, the non-neutral mode has its magnetic component orthogonal to the plane spanned by the directions of wave propagation and of the static magnetic field. The linear polarization is not maintained at higher orders. The results may be relevant to the microstructure in pulsar radiation or to the subpulses

  10. Recent Results of Helical Nonneutral Plasmas on Compact Helical System (CHS)

    International Nuclear Information System (INIS)

    Himura, H.; Yamamoto, Y.; Sanpei, A.; Masamune, S.; Wakabayashi, H.; Isobe, M.

    2006-01-01

    First of all, non-constant space potential φs and electron density ne on magnetic surfaces of helical nonneutral plasmas are verified experimentally. The difference in φs enlarges significantly at the outer region inside the closed magnetic surfaces, and the corresponding equipotential surfaces are inferred to shift upward vertically with respect to magnetic surfaces. Meanwhile, larger value of ne is clearly observed in the downward region (z < 0) of magnetic surfaces, which seems to be consistent with the φs measurement. These results are the first evidence which strongly suggests the equilibrium proposed for nonneutral plasmas confined in closed magnetic surfaces. Secondly, in order to investigate the mechanism of the multiple disruption of helical nonneutral plasmas observed in experiments, space and time evolutions of electron flux are measured carefully inside the magnetic surfaces, when the plasma disruption occurs. Surprisingly, a set of data show that the observed disruption is at first happened at ρ ∼ 0.8, where ρ is the normalized minor radius, and then, it seems to propagate inside magnetic surfaces

  11. Relaxation and self-organization of a nonneutral plasma

    International Nuclear Information System (INIS)

    Ramachandran, H.; Morales, G.J.; Decyk, V.K.

    1992-01-01

    The properties of nonneutral systems have been elucidated in several elegant experiments. As plasmas, these systems have the virtue of being confinable for long times, since conservation laws place strong bounds on particle loss. Detailed experiments have explored the quasistatic evolution of a well-confined configuration near equilibrium. The transient, non-equilibrium phase during which the plasma achieves its steady-state profile is difficult to probe experimentally. However, because of the short-time scales involved this is a regime well suited to particle simulation. This paper discusses the results of a particle-simulation code of a nonneutral plasma that is confined in a slab-equivalent of a Penning trap. The early collisionless relaxation is examined, and a time-dependent steady state is observed to result. In this state, the system achieves the shape of a football, composed of a fluid-like core and a kinetic halo. When this quasi-equilibrium is externally cooled, it is found to develop spatial rings reminiscent of liquid crystals. This crystalline structure is robust and 'melts' when it is heated. (author) 3 refs., 4 figs

  12. Study of Anti-Hydrogen and Plasma Physics 4.Observation of Antiproton Beams and Nonneutral Plasmas

    CERN Document Server

    Hori, Masaki; Fujiwara, Makoto; Kuroda, Naofumi

    2004-01-01

    Diagnostics of antiproton beams and nonneutral plasmas are described in this chapter. Parallel plate secondary electron emission detectors are used to non-destructively observe the beam position and intensity without loss. Plastic scintillation tracking detectors are useful in determining the position of annihilations of antiprotons in the trap. Three-dimensional imaging of antiprotons in a Penning trap is discussed. The unique capability of antimatter particle imaging has allowed the observation of the spatial distribution of particle loss in a trap. Radial loss is localized to small spots, strongly breaking the azimuthal symmetry expected for an ideal trap. By observing electrostatic eigen-modes of nonneutral plasmas trapped in the Multi-ring electrode trap, the non-destructive measurement of plasma parameters is performed.

  13. Overview of recent results from non-neutral plasmas in the CNT stellarator

    Science.gov (United States)

    Pedersen, T. Sunn; Boozer, A. H.; Brenner, P. W.; Durand de Gevigney, B.; Hahn, M. S.; Sarasola, X.; Senter, A.

    2009-11-01

    An overview of recent results from the Columbia Non-neutral Torus (CNT) will be given. CNT is a stellarator dedicated to studies of non-neutral and electron-positron plasmas [1]. CNT operates with a surplus of electrons -- most of the time with only a trace amount of ions (ni/ne Kremer et al., PRL 97, (2006) 095003 [3] P. W. Brenner et al., this poster session [4] Q. R. Marksteiner et al., PRL 100 (2008) 065002 [5] X. Sarasola Martin et al., this poster session [6] M. S. Hahn et al., Phys. Plasmas 16 (2009) 022105

  14. Compressional effects in nonneutral plasmas, a shallow water analogy and m=1 instability

    International Nuclear Information System (INIS)

    Finn, J.M.; Del-Castillo-Negrete, D.; Barnes, D.C.

    1999-01-01

    Diocotron instabilities form an important class of ExB shear flow instabilities which occur in nonneutral plasmas. The case of a single-species plasma confined in a cylindrical Penning trap, with an axisymmetric, hollow (nonmonotonic) density profile is studied. According to the standard linear theory, the m=1, k z =0 diocotron mode is always stable. On the other hand, experiments by Driscoll [Phys. Rev. Lett. 64, 645 (1990)] show a robust exponential growth of m=1 diocotron perturbations in hollow density profiles. The apparent contradiction between these experimental results and linear theory has been an outstanding problem in the theory of nonneutral plasmas. A new instability mechanism due to the radial variation of the equilibrium plasma length is proposed in this paper. This mechanism involves the compression of the plasma parallel to the magnetic field and implies the conservation of the line integrated density. The predicted growth rate, frequency, and mode structure are in reasonable agreement with the experiment. The effect of a linear perturbation of the plasma length is also shown to give instability with a comparable growth rate. The conservation of the line integrated density in the plasma is analogous to the conservation of the potential vorticity in the shallow water equations used in geophysical fluid dynamics. In particular, there is an analog of Rossby waves in nonneutral plasmas. copyright 1999 American Institute of Physics

  15. Toroidal confinement of non-neutral plasma - A new approach to high-beta equilibrium

    International Nuclear Information System (INIS)

    Yoshida, Z.; Ogawa, Y.; Morikawa, J.

    2001-01-01

    Departure from the quasi-neutral condition allows us to apply significant two-fluid effects that impart a new freedom to the design of high-performance fusion plasma. The self-electric field in a non-neutralized plasma induces a strong ExB-drift flow. A fast flow produces a large hydrodynamic pressure that can balance with the thermal pressure of the plasma. Basic concepts to produce a toroidal non-neutral plasma have been examined on the internal-conductor toroidal confinement device Proto-RT. A magnetic separatrix determines the boundary of the confinement region. Electrons describe chaotic orbits in the neighborhood of the magnetic null point on the separatrix. The chaos yields collisionless diffusion of electrons from the particle source (electron gun) towards the confinement region. Collisionless heating also occurs in the magnetic null region, which can be applied to produce a plasma. (author)

  16. First experimental result of toroidal confinement of non-neutral plasma on Proto-RT

    International Nuclear Information System (INIS)

    Himura, H.; Yoshida, Z.; Morikawa, J.

    1999-01-01

    Recently, an internal-ring device named Proto-RT (Prototype Ring Trap) was constructed at University of Tokyo, and experiments on the device have been just initiated. The goal of Proto-RT is to explore an innovative way which has a possibility to attain a plasma equilibrium with extremely high-β (β>1) in a toroidal geometry using non-neutral condition. At the first series of the experiments, pure electron plasma (n e ∼10 12 m -3 ) is successfully confined inside a separatrix. No disruption is so far observed. The confinement time of the electron plasma is the order of 1 sec. A shear effect of magnetic fields seems to result in longer confinement. The non-neutrality of Δn e ∼10 12 m -3 is already beyond the value required to produce an enough self-electric field E in plasma, causing a strong ExB flow thoroughly all over the plasma where the hydrodynamic pressure of the flow is predicted to balance with the thermal pressure of the plasma. (author)

  17. Period doubling of azimuthal oscillations on a non-neutral magnetized electron column

    International Nuclear Information System (INIS)

    Boswell, R.W.

    1985-01-01

    The low-frequency azimuthal oscillations on a non-neutral magnetized electron column of very low density are investigated. A perturbation analysis of the slow mode of the rigid rotator equilibrium is developed to illustrate the nature of large-amplitude fundamental-mode oscillations. The results of this theoretical analysis show two important characteristics: firstly, as the perturbation amplitude is increased the wave form ceases to be purely sinusoidal and shows period doubling. Secondly, above a certain threshold, all harmonics of the wave grow and the wave breaks. The results of the former are compared with a simple electron beam experiment and are found to be in good qualitative agreement. (author)

  18. The Columbia Non-neutral Torus

    International Nuclear Information System (INIS)

    Pedersen, Thomas Sunn

    2009-01-01

    Final report for the Columbia Non-neutral Torus. This details the results from the design, construction and initial operation of the Columbia Non-neutral Torus. During the duration of this grant, I designed, built, and operated the Columbia Nonneutral Torus, the world's lowest aspect ratio stellarator, and arguably, the world's simplest stellarator. This demonstrates the ease and robustness of the chosen stellarator design and allowed us to commence the investigation of the physics of non-neutral plasmas confined on magnetic surfaces. These plasmas are unique in many ways and had not previously been studied in a stellarator. Our first results showed that it is possible to confine and study a relatively cold pure electron plasma in a stellarator. We confirmed that the plasma is stable, and that the plasma is reasonably well confined in a stellarator configuration. These results were published in Physics of Plasmas (2006) and Physical Review Letters (2006). They enabled the existing program which is resolving the underlying transport processes in a classical stellarator with intense self-electric fields and enable the next phase of operation, electron-positron plasma physics. During the period of this grant, two students were trained in experimental plasma physics and both received their PhD degrees shortly after the grant terminated. One student is now employed in the financial services industry, the other is a postdoctoral associate at Los Alamos National Laboratory. The chief goals were to build and begin operation of the Columbia Non-neutral Torus. These goals were achieved in the third year of funding. The development of diagnostic methods and the confirmation of stable equilibria were also achieved during the grant period. In summary, the main scientific goals were all met. The main educational goals were also met, as the experiment became the training ground not only for the two aforementioned graduate students but also for a number of undergraduate students

  19. Magnetic cusp and electric nested- or single-well configurations for high density antihydrogen and fusion nonneutral plasma applications

    International Nuclear Information System (INIS)

    Ordonez, C. A.

    1999-01-01

    Malmberg-Penning traps have had limited uses for applications that require high density nonneutral plasma confinement. For such traps, the density is severely limited because a magnetic field is used to provide a radially inward force to balance both self-electric and centrifugal radially outward forces. A possible way to confine higher density nonneutral plasmas is to use a magnetic cusp configuration. An annular nonneutral plasma would be confined in the radial magnetic field of a magnetic cusp such that radial confinement is provided by an externally produced electric potential well while axial confinement is provided by the magnetic field. In addition, a radial electric potential profile having a nested-well configuration can be used to simultaneously confine two oppositely signed plasma species (e.g., positrons and antiprotons) that overlap. In the work reported, various aspects of using magnetic cusp configurations and electric nested-well configurations are considered. Plasma confinement with these configurations may be useful for obtaining fast antihydrogen recombination and trapping rates and for achieving practical fusion power production

  20. Magnetic Cusp and Electric Nested- or Single-Well Configurations for High Density Antihydrogen and Fusion Nonneutral Plasma Applications

    International Nuclear Information System (INIS)

    C.A. Ordonez

    1999-01-01

    Malmberg-Penning traps have had limited uses for applications that require high density nonneutral plasma confinement. For such traps, the density is severely limited because a magnetic field is used to provide a radially inward force to balance both self-electric and centrifugal radially outward forces. A possible way to confine higher density nonneutral plasmas is to use a magnetic cusp configuration. An annular nonneutral plasma would be confined in the radial magnetic field of a magnetic cusp such that radial confinement is provided by an externally produced electric potential well while axial confinement is provided by the magnetic field. In addition, a radial electric potential profile having a nested-well configuration can be used to simultaneously confine two oppositely signed plasma species (e.g., positrons and antiprotons) that overlap. In the work reported, various aspects of using magnetic cusp configurations and electric nested-well configurations are considered. Plasma confinement with these configurations may be useful for obtaining fast antihydrogen recombination and trapping rates and for achieving practical fusion power production

  1. Self-Similar Nonlinear Dynamical Solutions for One-Component Nonneutral Plasma in a Time-Dependent Linear Focusing Field

    International Nuclear Information System (INIS)

    Qin, Hong; Davidson, Ronald C.

    2011-01-01

    In a linear trap confining a one-component nonneutral plasma, the external focusing force is a linear function of the configuration coordinates and/or the velocity coordinates. Linear traps include the classical Paul trap and the Penning trap, as well as the newly proposed rotating-radio- frequency traps and the Mobius accelerator. This paper describes a class of self-similar nonlinear solutions of nonneutral plasma in general time-dependent linear focusing devices, with self-consistent electrostatic field. This class of nonlinear solutions includes many known solutions as special cases.

  2. Compression of a mixed antiproton and electron non-neutral plasma to high densities

    Science.gov (United States)

    Aghion, Stefano; Amsler, Claude; Bonomi, Germano; Brusa, Roberto S.; Caccia, Massimo; Caravita, Ruggero; Castelli, Fabrizio; Cerchiari, Giovanni; Comparat, Daniel; Consolati, Giovanni; Demetrio, Andrea; Di Noto, Lea; Doser, Michael; Evans, Craig; Fanì, Mattia; Ferragut, Rafael; Fesel, Julian; Fontana, Andrea; Gerber, Sebastian; Giammarchi, Marco; Gligorova, Angela; Guatieri, Francesco; Haider, Stefan; Hinterberger, Alexander; Holmestad, Helga; Kellerbauer, Alban; Khalidova, Olga; Krasnický, Daniel; Lagomarsino, Vittorio; Lansonneur, Pierre; Lebrun, Patrice; Malbrunot, Chloé; Mariazzi, Sebastiano; Marton, Johann; Matveev, Victor; Mazzotta, Zeudi; Müller, Simon R.; Nebbia, Giancarlo; Nedelec, Patrick; Oberthaler, Markus; Pacifico, Nicola; Pagano, Davide; Penasa, Luca; Petracek, Vojtech; Prelz, Francesco; Prevedelli, Marco; Rienaecker, Benjamin; Robert, Jacques; Røhne, Ole M.; Rotondi, Alberto; Sandaker, Heidi; Santoro, Romualdo; Smestad, Lillian; Sorrentino, Fiodor; Testera, Gemma; Tietje, Ingmari C.; Widmann, Eberhard; Yzombard, Pauline; Zimmer, Christian; Zmeskal, Johann; Zurlo, Nicola; Antonello, Massimiliano

    2018-04-01

    We describe a multi-step "rotating wall" compression of a mixed cold antiproton-electron non-neutral plasma in a 4.46 T Penning-Malmberg trap developed in the context of the AEḡIS experiment at CERN. Such traps are routinely used for the preparation of cold antiprotons suitable for antihydrogen production. A tenfold antiproton radius compression has been achieved, with a minimum antiproton radius of only 0.17 mm. We describe the experimental conditions necessary to perform such a compression: minimizing the tails of the electron density distribution is paramount to ensure that the antiproton density distribution follows that of the electrons. Such electron density tails are remnants of rotating wall compression and in many cases can remain unnoticed. We observe that the compression dynamics for a pure electron plasma behaves the same way as that of a mixed antiproton and electron plasma. Thanks to this optimized compression method and the high single shot antiproton catching efficiency, we observe for the first time cold and dense non-neutral antiproton plasmas with particle densities n ≥ 1013 m-3, which pave the way for an efficient pulsed antihydrogen production in AEḡIS.

  3. Confinement of nonneutral spheroidal plasmas in multi-ring electrode traps

    International Nuclear Information System (INIS)

    Mohri, Akihiro; Yuyama, Tetsumori; Michishita, Toshinori; Higaki, Hiroyuki; Tanaka, Hitoshi; Yamazawa, Yohei; Aoyagi, Masayuki

    1998-01-01

    A nonneutral spheroidal plasma can be settled in a rigid rotor equilibrium inside a closed conducting cell independently of induced image charges on the cell wall if the electrostatic potential distribution on the wall surface is set equal to the sum of the external hyperbolic potential (r 2 -2z 2 ) and the self-potential produced by the plasma. A confinement system equipped with a train of properly biased ring electrodes can approximately generate any axisymmetric potential, including the above field. Experiments on confinement of electron spheroids in such a system showed that the confinement time became the longest when the condition to diminish the image charge effects was satisfied. The observed frequency of the centre-of-mass harmonic oscillation of the plasma in this configuration was in good agreement with the estimated one. (author)

  4. Formation Process of Non-Neutral Plasmas by Multiple Electron Beams on BX-U

    Science.gov (United States)

    Sanpei, Akio; Himura, Haruhiko; Masamune, Sadao

    An imaging diagnostic system, which is composed of a handmade phosphor screen and a high-speed camera, has been applied to identify the dynamics of multiple electron beams on BX-U. The relaxation process of those toward a non-neutral plasma is experimentally identified. Also, the radial density profile of the plasma is measured as a function of time. Assuming that the plasma is a spheroidal shape, the value of electron density ne is in the range between 2.2 × 106 and 4.4 × 108 cm-3 on BX-U.

  5. Equilibrium state analysis of a nonneutral plasma under a uniform magnetic field

    International Nuclear Information System (INIS)

    Fernandez, J.E.; Molinari, V.G.; Sumini, M.A.

    1990-01-01

    By recourse to the Boltzmann H-theorem, the existence of a thermodynamic equilibrium state has been proved for a nonneutral plasma under an external magnetic field. The equation describing the density profile of ions or electrons has been found. The density equation has been numerically solved for a generic magnetic field and plasma frequency, giving a parametric limit for the confinement region. An appropriate change of variable allows to approximate the density equation whose analytical solution has been found. The approximated density closely fits the numerical solution of the original equation. (Author)

  6. Confinement of pure electron plasmas in the Columbia Non-neutral Torus

    International Nuclear Information System (INIS)

    Berkery, John W.; Pedersen, Thomas Sunn; Kremer, Jason P.; Marksteiner, Quinn R.; Lefrancois, Remi G.; Hahn, Michael S.; Brenner, Paul W.

    2007-01-01

    The Columbia Non-neutral Torus (CNT) [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois, Q. Marksteiner, N. Pomphrey, W. Reiersen, F. Dahlgreen, and X. Sarasola, Fusion Sci. Technol. 50, 372 (2006)] is a stellarator used to study non-neutral plasmas confined on magnetic surfaces. A detailed experimental study of confinement of pure electron plasmas in CNT is described here. Electrons are introduced into the magnetic surfaces by placing a biased thermionic emitter on the magnetic axis. As reported previously, the insulated rods holding this and other emitter filaments contribute to the radial transport by charging up negatively and creating ExB convective transport cells. A model for the rod-driven transport is presented and compared to the measured transport rates under a number of different conditions, finding good agreement. Neutrals also drive transport, and by varying the neutral pressure in the experiment, the effects of rod-driven and neutral-driven transport are separated. The neutral-driven electron loss rate scales linearly with neutral pressure. The neutral driven transport, presumably caused by electron-neutral collisions, is much greater than theoretical estimates for neoclassical diffusion in a classical stellarator with strong radial electric fields. In fact the confinement time is on the order of the electron-neutral collision time. Ion accumulation, electron attachment, and other effects are considered, but do not explain the observed transport rates

  7. Numerical calculation of axisymmetric non-neutral plasma equilibria

    International Nuclear Information System (INIS)

    Spencer, R.L.; Rasband, S.N.; Vanfleet, R.R.

    1993-01-01

    Efficient techniques for computing axisymmetric non-neutral plasma equilibria are described. These equilibria may be obtained either by requiring global thermal equilibrium, by specifying the midplane radial density profile, or by specifying the radial profile of ∫n dz. Both splines and finite-differences are used, and the accuracy of the two is compared by using a new characterization of the thermal equilibrium density profile which gives a simple formula for estimating the radial and axial gradient scale lengths of thermal equilibria. It is found that for global thermal equilibrium 1% accuracy is achieved with splines if the distance between neighboring splines is about two Debye lengths while finite differences require a grid spacing of about one-half Debye length to achieve the same accuracy

  8. Improved Temperature Diagnostic for Non-Neutral Plasmas with Single-Electron Resolution

    Science.gov (United States)

    Shanman, Sabrina; Evans, Lenny; Fajans, Joel; Hunter, Eric; Nelson, Cheyenne; Sierra, Carlos; Wurtele, Jonathan

    2016-10-01

    Plasma temperature diagnostics in a Penning-Malmberg trap are essential for reliably obtaining cold, non-neutral plasmas. We have developed a setup for detecting the initial electrons that escape from a trapped pure electron plasma as the confining electrode potential is slowly reduced. The setup minimizes external noise by using a silicon photomultiplier to capture light emitted from an MCP-amplified phosphor screen. To take advantage of this enhanced resolution, we have developed a new plasma temperature diagnostic analysis procedure which takes discrete electron arrival times as input. We have run extensive simulations comparing this new discrete algorithm to our existing exponential fitting algorithm. These simulations are used to explore the behavior of these two temperature diagnostic procedures at low N and at high electronic noise. This work was supported by the DOE DE-FG02-06ER54904, and the NSF 1500538-PHY.

  9. Numerical study on formation process of helical nonneutral plasmas using electron injection from outside magnetic surfaces

    International Nuclear Information System (INIS)

    Nakamura, Kazutaka; Himura, Haruhiko; Masamune, Sadao; Sanpei, Akio; Isobe, Mitsutaka

    2009-01-01

    In order to investigate the formation process of helical nonneutral plasmas, we calculate the orbits of electron injected in the stochastic magnetic field when the closed helical magnetic surfaces is correspond with the equipotential surfaces. Contrary to the experimental observation, there are no electrons inward penetrating. (author)

  10. Experimental observation of fluid echoes in a non-neutral plasma

    International Nuclear Information System (INIS)

    Yu, Jonathan H.; Driscoll, C. Fred

    2002-01-01

    Experimental observation of a nonlinear fluid echo is presented which demonstrates the reversible nature of spatial Landau damping, and that non-neutral plasmas behave as nearly ideal 2D fluids. These experiments are performed on UCSD's CamV Penning-Malmberg trap with magnetized electron plasmas. An initial m i =2 diocotron wave is excited, and the received wall signal damps away in about 5 wave periods. The density perturbation filaments are observed to wrap up as the wave is spatially Landau damped. An m t =4 'tickler' wave is then excited, and this wave also Landau damps. The echo consists of a spontaneous appearance of a third m e =2 wave after the responses to the first two waves have inviscidly damped away. The appearance time of the echo agrees with theory, and data suggests the echo is destroyed at least partly due to saturation

  11. The effect of externally applied oscillating electric fields on the l=1 and l=2 diocotron modes in non-neutral plasmas

    International Nuclear Information System (INIS)

    Spencer, R.L.

    1990-01-01

    A high-frequency oscillating electric field can change the properties of diocotron modes in non-neutral plasmas. The effect depends crucially on the azimuthal mode number, m, of the applied field. For m=0,±1 there is no effect, and for applied standing waves there is also no effect. But if the applied field has the form of a traveling wave with |m|≥2, the frequency of stable diocotron modes can be modified and for |m|≥3, the l=2 instability of hollow density profiles can be stabilized. The analytic results are verified with a nonlinear fluid simulation of an infinitely long non-neutral plasma

  12. Paul trap experiment to simulate intense nonneutral beam propagation through a periodic focusing field configuration

    CERN Document Server

    Davidson, R C; Majeski, R; Qin, H; Shvets, G

    2001-01-01

    This paper describes the design concept for a compact Paul trap experimental configuration that fully simulates the collective processes and nonlinear transverse dynamics of an intense charged particle beam that propagates over large distances through a periodic quadrupole magnetic field. To summarize, a long nonneutral plasma column (L>=r sub p) is confined axially by applied DC voltages V[circ]=const. on end cylinders at z=+-L, and transverse confinement is provided by segmented cylindrical electrodes (at radius r sub w) with applied oscillatory voltages +-V sub 0 (t) over 90 deg. segments. Because the transverse focusing force is similar in waveform to that produced by a discrete set of periodic quadrupole magnets in a frame moving with the beam, the Paul trap configuration offers the possibility of simulating intense beam propagation in a compact experimental facility. The nominal operating parameters in the experimental design are: barium ions (A=137); plasma column length 2L=2 m; wall radius r sub w =10...

  13. First observations of partially neutralized and quasineutral plasmas in the Columbia Non-neutral Torus

    Science.gov (United States)

    Sarasola, Xabier; Brenner, Paul; Hahn, Michael; Pedersen, Thomas

    2009-11-01

    The Columbia Non-neutral Torus (CNT) is the first stellarator devoted to the study of pure electron, partially neutralized and positron-electron plasmas. To date, CNT usually operates with electron rich plasmas (with negligible ion density) [1], but a stellarator can also confine plasmas of arbitrary degree of neutralization. In CNT the accumulation of ions alters the equilibrium of electron plasmas and a global instability has been observed when the ion fraction exceeds 10 %. A characterization of this instability is presented in [2], analyzing its parameter dependence and spatial structure (non- resonant with rational surfaces). A new set of experiments is currently underway studying plasmas of arbitrary degree of neutralization, ranging from pure electron to quasineutral plasmas. Basic observations show that the plasma potential decouples from emitter bias when we increase the degree of the neutralization of our plasmas. Partially neutralized plasmas are also characterized by multiple mode behavior with dominant modes between 20 and 200 kHz. When the plasma becomes quasineutral, it reverts to single mode behavior. The first results on partially neutralized plasmas confined on magnetic surfaces will be presented. [1] J. Kremer, PRL 97, (2006) 095003 [2] Q. Marksteiner, PRL 100 (2008) 065002

  14. Plasma Modes

    Science.gov (United States)

    Dubin, D. H. E.

    This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

  15. Laser surface wakefield in a plasma column

    International Nuclear Information System (INIS)

    Gorbunov, L.M.; Mora, P.; Ramazashvili, R.R.

    2003-01-01

    The structure of the wakefield in a plasma column, produced by a short intense laser pulse, propagating through a gas affected by tunneling ionization is investigated. It is shown that besides the usual plasma waves in the bulk part of the plasma column [see Andreev et al., Phys. Plasmas 9, 3999 (2002)], the laser pulse also generates electromagnetic surface waves propagating along the column boundary. The length of the surface wake wave substantially exceeds the length of the plasma wake wave and its electromagnetic field extends far outside the plasma column

  16. Parameter Dependence of Inward Diffusion on Injected Electrons in Helical Non-Neutral Plasmas

    International Nuclear Information System (INIS)

    Wakabayashi, H.; Himura, H.; Fukao, M.; Yoshida, Z.

    2003-01-01

    Experimental studies on an electron injection into a helical magnetic field and characteristics of non-neutral plasmas have been performed. It is found that the space potential φs has a weak dependence on the injection angle except for a narrow 'window' region in which φs significantly drops. A calculation shows that because of the electric field Eg of the electron gun (e-gun), the emitted electrons are launched quasi-parallel to the helical magnetic field B, regardless of α. This seems to agree with the observation. The 'window' seen in the data may be attributed to an current-driven instability which might result in the insufficient electron penetration or the degradation of electron confinement in the magnetic surface

  17. Toroidal equilibrium of a non-neutral plasma with toroidal current, inertia and pressure

    International Nuclear Information System (INIS)

    Bhattacharyya, S.N.; Avinash, K.

    1992-01-01

    Equilibrium of non-neutral clouds in a toroidal vessel with toroidal magnetic field is demonstrated in the presence of a toroidal current, finite mass and finite pressure. With a toroidal current, it is shown that in a large-aspect-ratio conducting torus the equilibrium is governed by competition between forces produced by image charges and image currents. When μ 0 ε 0 E r 2 >B θ 2 (whe re E r and B θ are the self electrostatic and self magnetic fields of the cloud), the confinement is electrostatic and plasma shifts inwards; when μ 0 ε 0 E r 2 θ 2 , the confinement is magnetic and plasma shifts outwards. For μ 0 ε 0 E r 2 = B θ 2 there is no equilibrium. With finite mass or finite pressure, it is shown, in a large-aspect-ratio approximation, that the fluid drift surfaces and equipotential surfaces are displaced with respect to each other. In both cases the fluid drift surfaces are shifted inwards from the equipotential surfaces. (author)

  18. Simulations of the instability of the m=1 self-shielding diocotron mode in finite-length nonneutral plasmas

    International Nuclear Information System (INIS)

    Mason, Grant W.; Spencer, Ross L.

    2002-01-01

    The 'self-shielding' m=1 diocotron mode in Malmberg-Penning traps has been known for over a decade to be unstable for finite length nonneutral plasmas with hollow density profiles. Early theoretical efforts were unsuccessful in accounting for the exponential growth and/or the magnitude of the growth rate. Recent theoretical work has sought to resolve the discrepancy either as a consequence of the shape of the plasma ends or as a kinetic effect resulting from a modified distribution function as a consequence of the protocol used to form the hollow profiles in experiments. We have investigated both of these finite length mechanisms in selected test cases using a three-dimensional particle-in-cell code that allows realistic treatment of shape and kinetic effects. We find that a persistent discrepancy of a factor of 2-3 remains between simulation and experimental values of the growth rate

  19. An investigation of transient pressures and plasma properties in a pinched plasma column. M.S. Thesis

    Science.gov (United States)

    Stover, E. K.; York, T. M.

    1971-01-01

    The transient pinched plasma column generated in a linear Z-pinch was studied experimentally and analytically. The plasma column was investigated experimentally with several plasma diagnostics; they were: a rapid response pressure transducer, a magnetic field probe, a voltage probe, and discharge luminosity. Axial pressure profiles on the discharge chamber axis were used to identify three characteristic regions of plasma column behavior: (1) strong axial pressure asymmetry noted early in plasma column lifetime, (2) followed by plasma heating in which there is a rapid rise in static pressure, and (3) a slight decrease static pressure before plasma column breakup. Plasma column lifetime was approximately 5 microseconds. The axial pressure asymmetry was attributed to nonsimultaneous pinching of the imploding current sheet along the discharge chamber axis. The rapid heating could be attributed in part to viscous effects introduced by radial gradients in the axial streaming velocity.

  20. An investigation of transient pressure and plasma properties in a pinched plasma column. M.S. Thesis

    Science.gov (United States)

    Stover, E. K.; York, T. M.

    1971-01-01

    The transient pinched plasma column generated in a linear Z-pinch was studied experimentally and analytically. The plasma column was investigated experimentally with the following plasma diagnostics: a special rapid response pressure transducer, a magnetic field probe, a voltage probe and discharge luminosity. Axial pressure profiles on the discharge chamber axis were used to identify three characteristic regions of plasma column behavior; they were in temporal sequence: strong axial pressure asymmetry noted early in plasma column lifetime followed by plasma heating in which there is a rapid rise in static pressure and a slight decrease static pressure before plasma column breakup. Plasma column lifetime was approximately 5 microseconds. The axial pressure asymmetry was attributed to nonsimultaneous pinching of the imploding current sheet along the discharge chamber axis. The rapid heating is attributed in part to viscous effects introduced by radial gradients in the axial streaming velocity. Turbulent heating arising from discharge current excitation of the ion acoustic wave instability is also considered a possible heating mechanism.

  1. Development of sausage-type instability in a Z-pinch plasma column

    International Nuclear Information System (INIS)

    Vikhrev, V.V.; Ivanov, V.V.; Rozanova, G.A.

    1993-01-01

    The development of sausage-type instabilities in an initially homogeneous Z-pinch plasma column has been investigated by means of numerical modelling. It is shown that in the presence of short-wave perturbations of a Z-pinch boundary and a rarefied plasma surrounding the pinch, cavities filled with a rarefied plasma and with a magnetic field are formed in the plasma column. As a result of this cavity growth, small columns of dense plasma form on the axis in the Z-pinch which have a temperature substantially higher than the average plasma temperature in the plasma column. When deuterium is present in the pinch, these dense high temperature bunches can become a source of intensive neutron radiation. (author). 24 refs, 7 figs

  2. Simulations of the instability of the m=1 self-shielding diocotron mode in finite-length non-neutral plasmas

    International Nuclear Information System (INIS)

    Mason, Grant W.; Spencer, Ross L.

    2002-01-01

    The 'self-shielding' m=1 diocotron mode in Malmberg-Penning traps has been known for over a decade to be unstable for finite length non-neutral plasmas with hollow density profiles. Early theoretical efforts were unsuccessful in accounting for the exponential growth and/or the magnitude of the growth rate. Recent theoretical work has sought to resolve the discrepancy either as a consequence of the shape of the plasma ends or as a kinetic effect resulting from a modified distribution function as a consequence of the protocol used to form the hollow profiles in experiments. Both of these finite length mechanisms have been investigated in selected test cases using a three-dimensional particle-in-cell code that allows realistic treatment of shape and kinetic effects. A persistent discrepancy of a factor of 2-3 remains between simulation and experimental values of the growth rate. Simulations reported here are more in agreement with theoretical predictions and fail to explain the discrepancy

  3. Exhaust properties of centre-column-limited plasmas on MAST

    International Nuclear Information System (INIS)

    Maddison, G.P.; Akers, R.J.; Brickley, C.; Gryaznevich, M.P.; Lott, F.C.; Patel, A.; Sykes, A.; Turner, A.; Valovic, M.

    2007-01-01

    The lowest aspect ratio possible in a spherical tokamak is defined by limiting the plasma on its centre column, which might therefore maximize many physics benefits of this fusion approach. A key issue for such discharges is whether loads exhausted onto the small surface area of the column remain acceptable. A first series of centre-column-limited pulses has been examined on MAST using fast infra-red thermography to infer incident power densities as neutral-beam heating was scanned from 0 to 2.5 MW. Simple mapping shows that efflux distributions on the column armour are governed mostly by magnetic geometry, which moreover spreads them advantageously over almost the whole vertical length. Hence steady peak power densities between sawteeth remained low, -2 , comparable with the target strike-point value in a reference diverted plasma at lower power. Plasma purity and normalized thermal energy confinement through the centre-column-limited (CCL) series were also similar to properties of MAST diverted cases. A major bonus of CCL geometry is a propensity for exhaust to penetrate through its inner scrape-off layer connecting to the column into an expanding outer plume, which forms a 'natural divertor'. Effectiveness of this process may even increase with plasma heating, owing to rising Shafranov shift and/or toroidal rotation. A larger CCL device could potentially offer a simpler, more economic next-step design

  4. a Theoretical Study of Coherent Structures in Nonneutral Plasma Columns

    Science.gov (United States)

    Lund, Steven M.

    A ubiquitous feature of experimental and computer simulation studies of magnetically confined pure electron plasmas in cylindrical confinement devices is the formation of nonaxisymmetric (partial/partial theta ne 0) rotating equilibria. In this dissertation, nonaxisymmetric rotating equilibria are investigated theoretically for strongly magnetized, low-density (omega_sp{pe} {2}/omega_sp{ce}{2 } guiding-center model in the cold-fluid limit (the continuity and Poisson equations) that treats the electrons as a massless fluid (m_{e} to 0) with E times B flow velocity V _{e} = -(c/B_0)nablaphi times {bf e}_{z}. Within this model, general rotating equilibria with electron density (n_{e} equiv n_{R}(r,theta-omega _{r}t) and electrostatic potential phi equiv phi_{R }(r,theta-omega_{r}t) have the property that the electron density is functionally related to the streamfunction psi _{R} = -ephi_{R} + omega_{r}(eB_0/2c)r^2 by n_{R} = n_{R }(psi_{R}). The streamfunction psi_{R} satisfies the nonlinear equilibrium equation nabla ^2psi_{R} = -4pi e^2n _{R}(psi_{R}) + 2omega_{r}eB_0/c with psi_{R} = omega _{r}(eB_0/2c)r_sp{w }{2} equiv psi_{w } = const. on the cylindrical wall at r = r_{w}. A general methodology for the solution of this equilibrium system is presented and several properties of rotating equilibria are analyzed. Following this analysis, two classes of nonaxisymmetric equilibria are investigated. These two classes of equilibria can have large amplitude (strongly nonaxisymmetric). First, a class of vortex-like rotating equilibria is analyzed that is characterized by a structured density profile that fills a confinement geometry with an inner conducting cylinder at radius r = r_{I} Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).

  5. Characteristics of an elongated plasma column produced by magnetically coupled hollow cathode plasma source

    Science.gov (United States)

    Bhuva, M. P.; Karkari, S. K.; Kumar, Sunil

    2018-03-01

    An elongated plasma column in the presence of an axial magnetic field has been formed using a cylindrical hollow cathode (HC) and a constricted anode (CA). The plasma characteristics of the central line have been found to vary with the magnetic field strength and the axial distance from the source. It is believed that the primary electrons constituting the discharge current are steered by the axial magnetic field to undertake ionizing collisions along the plasma column. The current carrying electrons from the HC reach the anode by cross-field diffusion towards the central line. The above observation has been substantiated using a phenomenological model which links the observed characteristics of the source with the plasma column. The experimental results are found to be in qualitative agreement with the model.

  6. A perspective on the contributions of Ronald C. Davidson to plasma physics

    Science.gov (United States)

    Wurtele, Jonathan S.

    2016-10-01

    Starting in the 1960s and continuing for half a century, Ronald C. Davidson made fundamental theoretical contributions to a wide range of areas of pure and applied plasma physics. Davidson was one of the founders of nonneutral plasma physics and a pioneer in developing and applying kinetic theory and nonlinear stability theorems to collective interaction processes and nonlinear dynamics of nonneutral plasmas and intense charged particle beams. His textbooks on nonneutral plasmas are the classic references for the field and educated generations of graduate students. Davidson was a strong advocate for applying the ideas of plasma theory to develop techniques that benefit other branches of science. For example, one of the major derivative fields enabled by nonneutral plasmas is the study of antimatter plasmas and the synthesis of antihydrogen. This talk will review a few highlights of Ronald Davidson's impact on plasma physics and related fields of science.

  7. Nonneutralized charge effects on tokamak edge magnetohydrodynamic stability

    International Nuclear Information System (INIS)

    Zheng, Linjin; Horton, W.; Miura, H.; Shi, T.H.; Wang, H.Q.

    2016-01-01

    Owing to the large ion orbits, excessive electrons can accumulate at tokamak edge. We find that the nonneutralized electrons at tokamak edge can contribute an electric compressive stress in the direction parallel to magnetic field by their mutual repulsive force. By extending the Chew–Goldburger–Low theory (Chew et al., 1956 [13]), it is shown that this newly recognized compressive stress can significantly change the plasma average magnetic well, so that a stabilization of magnetohydrodynamic modes in the pedestal can result. This linear stability regime helps to explain why in certain parameter regimes the tokamak high confinement can be rather quiet as observed experimentally.

  8. Plasma-column instabilities in a reversed-field pinch without a shell

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell.

  9. Plasma-column instabilities in a reversed-field pinch without a shell

    International Nuclear Information System (INIS)

    Schmid, P.G.

    1988-01-01

    Plasma column instabilities in a Reversed Field Pinch (RFP) without a shell were investigated in the Colorado Reversatron RFP. The Reversatron RFP (aspect ration R/a = 50 cm/8cm) is a toroidal plasma containment device consisting of a vacuum chamber, a thick conducting shell, modular shells, magnetic field producing coils and diagnostics to characterize the plasma. RFP discharges were set up in the Reversatron in three different experimental configurations: with a thick conducting shell, with a modular shell and with no shell. In two of the configurations, a shell enclosed the plasma column to provide some plasma stability. A vertical magnetic field provided equilibrium in experiments without a shell. Data from discharges without a shell indicated that the plasma duration was greatly reduced and the plasma resistance increased compared to the discharges with a thick shell. Plasma position probes indicated large plasma centriod displacements corresponding to a n = 1 and a n = 3 kink coincident with the peak of the plasma current and the start of a discharge termination phase. The modular shell lengthened the discharge duration and lowered the plasma resistance to values intermediate between the plasma with a thick shell and the plasma with no shell. The modular shell suppressed the large plasma column displacements observed in the RFP plasma without a shell

  10. CO2-laser--produced plasma columns in a solenoidal magnetic field

    International Nuclear Information System (INIS)

    Offenberger, A.A.; Cervenan, M.R.; Smy, P.R.

    1976-01-01

    A 1-GW CO 2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm-long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave travelling out of the solenoid back toward the focusing lens. Target burns give direct evidence for trapped laser beam propagation along the plasma column

  11. Efficient simulation and likelihood methods for non-neutral multi-allele models.

    Science.gov (United States)

    Joyce, Paul; Genz, Alan; Buzbas, Erkan Ozge

    2012-06-01

    Throughout the 1980s, Simon Tavaré made numerous significant contributions to population genetics theory. As genetic data, in particular DNA sequence, became more readily available, a need to connect population-genetic models to data became the central issue. The seminal work of Griffiths and Tavaré (1994a , 1994b , 1994c) was among the first to develop a likelihood method to estimate the population-genetic parameters using full DNA sequences. Now, we are in the genomics era where methods need to scale-up to handle massive data sets, and Tavaré has led the way to new approaches. However, performing statistical inference under non-neutral models has proved elusive. In tribute to Simon Tavaré, we present an article in spirit of his work that provides a computationally tractable method for simulating and analyzing data under a class of non-neutral population-genetic models. Computational methods for approximating likelihood functions and generating samples under a class of allele-frequency based non-neutral parent-independent mutation models were proposed by Donnelly, Nordborg, and Joyce (DNJ) (Donnelly et al., 2001). DNJ (2001) simulated samples of allele frequencies from non-neutral models using neutral models as auxiliary distribution in a rejection algorithm. However, patterns of allele frequencies produced by neutral models are dissimilar to patterns of allele frequencies produced by non-neutral models, making the rejection method inefficient. For example, in some cases the methods in DNJ (2001) require 10(9) rejections before a sample from the non-neutral model is accepted. Our method simulates samples directly from the distribution of non-neutral models, making simulation methods a practical tool to study the behavior of the likelihood and to perform inference on the strength of selection.

  12. Magneto-acoustic resonance in a non-uniform current carrying plasma column

    OpenAIRE

    Vaclavik, J.

    2017-01-01

    The forced radial magneto-acoustic oscillations in a plasma column with nonuniform mass density and temperature are investigated. It turns out that the oscillations have a resonant character similar to that of the magneto-acoustic oscillations in a uniform plasma column. The properties of the axial and azimuthal components of the oscillating magnetic field are discussed in detail

  13. Conditions for sustaining low-pressure plasma columns by travelling electromagnetic UHF waves

    International Nuclear Information System (INIS)

    Benova, E.; Zhelyazkov, I.

    1997-01-01

    The paper considers the conditions for sustaining low-pressure plasma columns by travelling electromagnetic waves in symmetric and dipolar modes, respectively. The treatment is fully electrodynamic. It is shown that the wave energy flux along the plasma column determines the conditions for sustaining the discharge. In particular as the plasma is sustained by a symmetric wave whose flux depends mainly on the radial distribution of the wave electric field whilst for a dipolar wave sustained plasma the flux is specified by the magnitude of the axial wave field component at the plasma-dielectric interface. (orig.)

  14. Electric field strength in a silicon surface barrier detector with the presence of a dielectric plasma column

    International Nuclear Information System (INIS)

    Kanno, Ikuo

    1994-01-01

    The dynamic change of the electric field strength in a silicon surface barrier detector (SSBD) is studied. With the presence of a dielectric plasma column in the depletion layer of the SSBD, the electric field strength inside/outside the plasma column is suppressed/enhanced. As the length and the dielectric constant of the plasma column become shorter and smaller, the suppression and enhancement of the electric field strength become less. The electric field strength recovers the initial state, when the plasma column disappears. When the electrons and holes are inside/outside the dielectric plasma column, they have less/more electric potential than the one they have when there is no plasma column. During the movement of the electron/hole outside the plasma column to the positive/negative electrode, the enhanced electric field strength becomes smaller. Electron and hole pairs, which are the parts of the dielectric plasma column, arrive at positive and negative electrodes, having insufficient electric potential to induce the unit charge. This paper shows that the presence of a dielectric plasma column explains the main part of the residual defect in a SSBD. ((orig.))

  15. Propagation and diffusion of a plasma column in a magnetic field

    International Nuclear Information System (INIS)

    Bottiglioni, F.; Coutant, J.; Gadda, E.; Prevot, F.

    1966-12-01

    A plasma column is created in a magnetic field by longitudinal diffusion from a low-pressure pulsed discharge in hydrogen. Depending on the discharge conditions, two regimes are obtained in which the gas pumping speed has a different effect upon the plasma density in the column. Calculations are presented which can explain this effect by a difference in the transverse diffusion coefficient. (authors) [fr

  16. Ready-made chromatography columns for extracellular vesicle isolation from plasma

    Directory of Open Access Journals (Sweden)

    Joanne Louise Welton

    2015-03-01

    Full Text Available Proteomic studies of circulating vesicles are hampered by difficulties in purifying vesicles from plasma and serum. Isolations are contaminated with high-abundance blood proteins that may mask genuine vesicular-associated proteins and/or simply provide misleading data. In this brief report, we explored the potential utility of a commercially available size exclusion chromatography column for rapid vesicle purification. We evaluated the performance of the column, with cancer cell line conditioned medium or healthy donor plasma, in terms of removing non-vesicular protein and enriching for vesicles exhibiting exosome characteristics. Serial fractions revealed a peak for typical exosomal proteins (CD9, CD81 etc. that preceded the peak for highly abundant proteins, including albumin, for either sample type, and harvesting only this peak would represent elimination of >95% of protein from the sample. The columns showed good reproducibility, and streamlining the workflow would allow the exosome-relevant material to be collected in less than 10 minutes. Surprisingly, however, subsequent post-column vesicle concentration steps whilst resulting in some protein loss also lead to low vesicle recoveries, with a net effect of reducing sample purity (assessed by the particle-to-protein ratio. The columns provide a convenient, reproducible and highly effective means of eliminating >95% of non-vesicular protein from biological fluid samples such as plasma.

  17. Nonlinear electrostatic ion-acoustic "oscilliton" waves driven by charge non-neutrality effects

    Directory of Open Access Journals (Sweden)

    J. Z. G. Ma

    2011-01-01

    Full Text Available Nonlinear "oscilliton" structures features a low-frequency (LF solitary envelope, the amplitude of which is modulated violently by superimposed high-frequency (HF oscillations. We have studied the charge non-neutrality effects on the excitation of electrostatic ion-acoustic (IA oscillitons. A two-fluid, warm plasma model is employed, and a set of nonlinear self-similar equations is solved in a cylindrical geometry. Under charge-neutrality conditions, three conventional IA structures (namely, sinusoidal, sawtooth, and spicky/bipolar are obtained. By contrast, under charge non-neutrality conditions, oscilliton structures are excited, where the LF envelope is in the sound-wave (SW mode, while the HF ingredients include the IA mode and the ion-Langmiur (IL mode. The amplitudes of the SW wave are violently modulated by the IA oscillations, whereas the upward sides of the IA amplitudes are modulated by the IL oscillations of smaller amplitudes, and the downward sides are modulated by hybrid IA/IL oscillations. The nonlinear oscillitons are found to be dependent not only upon the input parameters (e.g., the Mach number, the Debye length, and the initial temperature of particles, but on initial conditions as well.

  18. Collisional transport in nonneutral plasmas

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1999-01-01

    Classical transport theory grossly underestimates collisionally-driven cross-field transport for plasmas in the parameter regime of r c D , where r c ≡ v-bar/Ω c , λ D 2 ≡ T/4πe 2 n. In current experiments operating in this regime, cross-field test particle transport is observed to be a factor of 10 larger than the prediction of classical theory. Heat conduction is enhanced by up to 300 times over classical theory, and viscosity is up to 10 4 times larger. New guiding center theories of transport due to long-range collisions have been developed that agree with the measurements. Theory also predicts that emission and absorption of plasma waves may further enhance the thermal conduction and viscosity, providing a possible mechanism for anomalous thermal conductivity in the electron channel of fusion plasmas. (author)

  19. Determination of plasma column transverse section in the TBR-1 tokamak

    International Nuclear Information System (INIS)

    Conde, M.E.

    1986-01-01

    The temporal evolution of plasma column transverse section in the TBR-1 tokamak is determined. The experimental melhod is based on the simulation of toroidal current distribution in plasma by a set of toroidal filaments. The currents in these filaments are determined by minimization of square error between the magnetic field produced by filaments and the field measured into the tokamak vacuum vessel. For the measurement of magnetic field, twenty small magnetic coils were constructed and installated in the region protected by current limiters. The plasma column transverse cross section is determined by poloidal field produced by the currents in filaments. The multipole moments of plasma current distribution and the Λ Shafranov parameter were obtained. (M.C.K.) [pt

  20. Rotation of a magnesium plasma column in a background gas

    International Nuclear Information System (INIS)

    Bosco, E. Del; Dallaqua, R.S.

    1993-01-01

    Measurements of the angular velocity of a plasma column in a surrounding gas atmosphere are presented. The plasma is produced by a pulsed, high current arc discharge in the presence of an axial magnetic field. The angular velocity is measured using the cross correlation technique applied to the floating potential signals measured by two Langmuir probes. The main result is that when gas is added to the discharge the angular velocity is always lower than the case when there is no gas, this effect been more pronounced in the beginning of the discharge. For pressures higher than ∼ 2 x 10 -2 Pa there is a effect of the gas on the plasma column rotation and the angular velocity diminishes even at the end of discharge. (author)

  1. Measurement of electric field distribution along the plasma column in Microwave jet discharges at atmospheric pressure

    International Nuclear Information System (INIS)

    Razzak, M. Abdur; Takamura, Shuichi; Tsujikawa, Takayuki; Shibata, Hideto; Hatakeyama, Yuto

    2009-01-01

    A new technique for the direct measurement of electric field distribution along the plasma column in microwave jet discharges is developed and employed. The technique is based on a servomotor-controlled reciprocating antenna moving along the nozzle axis and plasma column. The measurement technique is applied to a rectangular waveguide-based 2.45 GHz argon and helium plasma jets generated by using the modified TIAGO nozzle at atmospheric pressure with a microwave power of less than 500 W. The measurement has been done with and without igniting the plasma jet in order to investigate the standing wave propagation along the nozzle axis and plasma column. It is observed that the electric field decay occurs slowly in space with plasma ignition than that of without plasma, which indicates the surface electromagnetic wave propagation along the plasma column in order to sustain the plasma jet. This study enables one to design, determine and optimize the size and structure of launcher nozzle, which plays an important role for the stable and efficient microwave plasma generators. (author)

  2. Study of scattering cross section of a plasma column using Green's function volume integral equation method

    Science.gov (United States)

    Soltanmoradi, Elmira; Shokri, Babak

    2017-05-01

    In this article, the electromagnetic wave scattering from plasma columns with inhomogeneous electron density distribution is studied by the Green's function volume integral equation method. Due to the ready production of such plasmas in the laboratories and their practical application in various technological fields, this study tries to find the effects of plasma parameters such as the electron density, radius, and pressure on the scattering cross-section of a plasma column. Moreover, the incident wave frequency influence of the scattering pattern is demonstrated. Furthermore, the scattering cross-section of a plasma column with an inhomogeneous collision frequency profile is calculated and the effect of this inhomogeneity is discussed first in this article. These results are especially used to determine the appropriate conditions for radar cross-section reduction purposes. It is shown that the radar cross-section of a plasma column reduces more for a larger collision frequency, for a relatively lower plasma frequency, and also for a smaller radius. Furthermore, it is found that the effect of the electron density on the scattering cross-section is more obvious in comparison with the effect of other plasma parameters. Also, the plasma column with homogenous collision frequency can be used as a better shielding in contrast to its inhomogeneous counterpart.

  3. Stability of Non-Neutral Plasma Cylinder Consisting of Magnetized Cold Electrons and of Small Density Fraction of Ions Born at Rest: Non-Local Analysis

    International Nuclear Information System (INIS)

    Yeliseyev, Y. N.

    2009-01-01

    The non-local stability problem of the plasma cylinder, filled with 'cold' magnetized rigidly rotating electrons, and a small density fraction of ions, is solved. The ions are supposed to be born at rest by ionization of background gas. The study is based on the kinetic description of ions. The equilibrium distribution function, taking into account the peculiarity of ions birth, is used. The radial electric field is caused by space charge of non-neutral plasma. The dispersion equation for plasma eigen frequencies is obtained analytically. It is valid within the total admissible range of values of electric and magnetic fields. Normalized eigen frequencies ω'/Ω i are calculated for the basic azimuth mode m = 1(ω' ω-mω i + , ω + = (-ω ci +Ω i )/2, Ω i (ω ci 2 -4eE r /m i r) 1/2 is called the 'modified' ion cyclotron (MIC) frequency), for the density fraction of ions of atomic nitrogen f N i /n e = 0,01 and are presented in graphic form versus parameter 2ω pe 2 /ω ce 2 . The spectra of oscillations ω'/Ω i consist of the family of electron Trivel-piece--Gould (TG) modes and of the families of MIC modes. The frequencies of MIC modes are located in a small vicinity of harmonics of the MIC frequency Ω i above and below the harmonic. The TG modes in non-neutral plasma fall in the region of MIC frequencies Ω i and interact strongly with MIC modes. The slow TG modes become unstable near the crossings with non-negative harmonics of MIC frequencies. The instabilities have a resonant character. The lowest radial TG mode has a maximum growth rate at crossing with a zero harmonic of Ω i ((Im ω'/Ω i ) max ≅0,074). The growth rates of MIC modes are much lower ((Im ω'/Ω i ) max pe 2 /ω ce 2 , corresponding to strong radial electric fields (ω ci 2 r /m i r|), in which the ions are unmagnetized. The oscillations of small amplitude are seen on some frequency dependencies of MIC modes. They are similar to oscillations on dispersion curves of electron waves in

  4. Effect of finite conductivity on the vertical stability of a tokamak plasma column with a noncircular cross section without conducting shell

    International Nuclear Information System (INIS)

    Sakurai, Keiichi; Okuda, Takayoshi; Tanaka, Yuji.

    1977-01-01

    The effect of finite conductivity on the stability of a tokamak plasma column with noncircular cross section without conducting shell was investigated by considering the current filaments model. The study is made for the plasma with rectangular cross section, and in this case, the position control of plasma column is a serious problem. The equation of motion of the plasma column is described for the vertical force applied to the column. The calculation of stability was made for the cases with cross sections of circular, rectangular and D type shapes. The plasma column was considered as an assembly of a lot of circular conductors, and this method can be applied to the plasma column with proper distribution of conductivity. As the results of calculation, it can be said that the electromotive force produced by the column moving in the magnetic field generates surface current on the plasma column, and in case of the finite conductivity of plasma, this current attenuates with time, and the distribution of the current soaks into the plasma column. Consequently, the recovery force acting on the plasma column is reduced, but contributes to the vertical stabilization for several hundreds μsec. (Kato, T.)

  5. Helicon wave coupling to a chiral-plasma column

    International Nuclear Information System (INIS)

    Torres-Silva, H.; Reggiani, N.; Sakanaka, P.H.

    1995-01-01

    Inductive helicon wave coupling to a chiro-plasma column is studied numerically. In our theoretical model, the RF current distribution of the chiro-plasma is taken into account using the constitutive relations of a chiral-plasma. Computational results based on the data of present-day helicon devices are show. In particular, we discuss the role of magnetic-field-aligned electron landau damping for the helicon wave absorption. In many a see, the numerical findings can be understood reasonably in terms of the wavenumber spectra of the helicon wave dispersion relation for slow and fast wave of a chiral-plasma. In general however, the full electromagnetic treatment is necessary in order to describe and to understand the inductive coupling in the helicon wave regime. (author). 9 refs., 1 fig

  6. Resistive mode in rotating plasma columns including the hall current

    International Nuclear Information System (INIS)

    Galvao, R.M.O.

    1983-01-01

    A new resistive mode is shown to exist in rotating plasma columns. The mode is localized in the neighbourhood of the radius where the angular velocity of the bulk plasma is equal to minus half the local angular velocity of the ions. This singular point is caused by the Hall term in the generalized Ohm law. The growth rate of the mode scales with eta sup(1/2), where eta is the plasma resistivity. (Author) [pt

  7. Stability of Non-Neutral Plasma Cylinder Consisting of Magnetized Cold Electrons and of Small Density Fraction of Ions Born at Rest: Non-Local Analysis

    Science.gov (United States)

    Yeliseyev, Y. N.

    2009-03-01

    The non-local stability problem of the plasma cylinder, filled with "cold" magnetized rigidly rotating electrons, and a small density fraction of ions, is solved. The ions are supposed to be born at rest by ionization of background gas. The study is based on the kinetic description of ions. The equilibrium distribution function, taking into account the peculiarity of ions birth, is used. The radial electric field is caused by space charge of non-neutral plasma. The dispersion equation for plasma eigen frequencies is obtained analytically. It is valid within the total admissible range of values of electric and magnetic fields. Normalized eigen frequencies ω'/Ωi are calculated for the basic azimuth mode m = 1 (ω' = ω-mωi+, ω+ = (-ωci+Ωi)/2, Ωi = (ωci2-4eEr/mir)1/2 is called the "modified" ion cyclotron (MIC) frequency), for the density fraction of ions of atomic nitrogen f = Ni/ne = 0,01 and are presented in graphic form versus parameter 2ωpe2/ωce2. The spectra of oscillations ω'/Ωi consist of the family of electron Trivel-piece—Gould (TG) modes and of the families of MIC modes. The frequencies of MIC modes are located in a small vicinity of harmonics of the MIC frequency Ωi above and below the harmonic. The TG modes in non-neutral plasma fall in the region of MIC frequencies Ωi and interact strongly with MIC modes. The slow TG modes become unstable near the crossings with non-negative harmonics of MIC frequencies. The instabilities have a resonant character. The lowest radial TG mode has a maximum growth rate at crossing with a zero harmonic of Ωi ((Im ω'/Ωi)max≈0,074). The growth rates of MIC modes are much lower ((Im ω'/Ωi)max≲0,002). Their instability has a threshold character. The instabilities of TG and MIC modes take place mainly at the values of parameter 2ωpe2/ωce2, corresponding to strong radial electric fields (ωci2≪|eEr/mir|), in which the ions are unmagnetized. The oscillations of small amplitude are seen on some frequency

  8. Multipole traps for non-neutral plasmas

    International Nuclear Information System (INIS)

    Tiouririne, T.N.; Turner, L.; Lau, A.W.C.

    1994-01-01

    A multipolar generalization of the Penning trap is presented. The case of l=1 is that of standard Penning trap. For the case of a quadrupolar magnetic field, analytic solutions are presented for cold, confined, one-species plasmas with spheroidal or spherical boundaries; for higher l values analytic solutions are given only for spherically bounded plasmas. By virtue of the sheared flow present for solutions with l>1, the classical Brillouin ratio (stored rest energy of particles/stored magnetic energy) of unity is exceeded and attains a global limit of 2 at infinitely high l

  9. REUSABILITY OF BOND ELUT CERTIFY COLUMNS FOR THE EXTRACTION OF DRUGS FROM PLASMA

    NARCIS (Netherlands)

    CHEN, XH; FRANKE, JP; WIJSBEEK, J; DEZEEUW, RA

    1993-01-01

    The reusability of Bond Elut Certify columns for the extraction of toxicologically relevant drugs from plasma has been evaluated. Pentobarbital, hexobarbital, mepivacaine, trimipramine and clonazepam were selected as test drugs to represent various classes of drugs. The columns were regenerated

  10. CFD Modeling of Non-Neutral Atmospheric Boundary Layer Conditions

    DEFF Research Database (Denmark)

    Koblitz, Tilman

    model results. A method is developed how to simulate the time-dependant non-neutral ABL flow over complex terrain: a precursor simulation is used to specify unsteady inlet boundary conditions on complex terrain domains. The advantage of the developed RANS model framework is its general applicability...... characteristics of neutral and non-neutral ABL flow. The developed ABL model significantly improves the predicted flow fields over both flat and complex terrain, when compared against neutral models and measurements....... cost than e.g. using large-eddy simulations. The developed ABL model is successfully validated using a range of different test cases with increasing complexity. Data from several large scale field campaigns, wind tunnel experiments, and previous numerical simulations is presented and compared against...

  11. Extreme degree of ionization in homogenous micro-capillary plasma columns heated by ultrafast current pulses.

    Science.gov (United States)

    Avaria, G; Grisham, M; Li, J; Tomasel, F G; Shlyaptsev, V N; Busquet, M; Woolston, M; Rocca, J J

    2015-03-06

    Homogeneous plasma columns with ionization levels typical of megaampere discharges are created by rapidly heating gas-filled 520-μm-diameter channels with nanosecond rise time current pulses of 40 kA. Current densities of up to 0.3  GA cm^{-2} greatly increase Joule heating with respect to conventional capillary discharge Z pinches, reaching unprecedented degrees of ionization for a high-Z plasma column heated by a current pulse of remarkably low amplitude. Dense xenon plasmas are ionized to Xe^{28+}, while xenon impurities in hydrogen discharges reach Xe^{30+}. The unique characteristics of these hot, ∼300:1 length-to-diameter aspect ratio plasmas allow the observation of unexpected spectroscopic phenomena. Axial spectra show the unusual dominance of the intercombination line over the resonance line of He-like Al by nearly an order of magnitude, caused by differences in opacities in the axial and radial directions. These plasma columns could enable the development of sub-10-nm x-ray lasers.

  12. Plasma Science Committee (PLSC) and the Panel on Opportunities in Plasma Science and Technology (OPST)

    International Nuclear Information System (INIS)

    1993-01-01

    The Plasma Science Committee (PLSC) of the National Research Council (NRC) is charged with monitoring the health of the field of plasma science in the United States and identifies and examines both broad and specific issues affecting the field. Regular meetings, teleconferences, briefings from agencies and the scientific community, the formation of study panels to prepare reports, and special symposia are among the mechanisms used by the PLSC to meet its charge. During July 1992, the PLSC sponsored a workshop on nonneutral plasmas in traps. Although no written report on the workshop results, was prepared for public distribution, a summary of highlights was provided to the OPST Subpanel on Nonneutral Plasmas. The PLSC also continued its follow-up briefings and discussions on the results of the results of the report Plasma Processing of materials. Scientific and Technological Opportunities. As a result of these activities, the Committee is now working with the NRC Committee on Atomic, Molecular, and Optical Sciences (CAMOS) to organize a symposium on database needs in plasma processing of materials

  13. Influence of a cylindrical column of rotating plasma on stability

    International Nuclear Information System (INIS)

    Rossato, L.C.

    1975-01-01

    The kink instability of a cylindrical column of rotating plasma, liable to a perturbation of the form f (r) exp [i(m -kz) + wt], under a condition kr<< m, was studied. It was concluded that as we increase the rotation, the interval of possible instabilities decreases. When the speed of rotation in the outlines of the plasma is equal to the speed of Alfven we will surely have stability. (author)

  14. Determination of the plasma column shape in the Tokamak Novillo cross section by magnetic probes

    International Nuclear Information System (INIS)

    Hernandez Omana, A.

    1993-01-01

    The determination of plasma cross section shape in Tokamaks is an important diagnostic method for equilibrium conditions analysis. In this work, it is obtained a time dependent variation of the plasma column cross section in Novillo Tokamak. The experimental method is based on using one magnetic probe, which is installed inside of the vacuum vessel in a 1 mm. wall thickness stainless steel tube, in the protected region of the limiter shadow. The plasma column cross section is determined measuring the poloidal magnetic field produced by the plasma current. This method, now running for determining the plasma column shape, requires the measurement of magnetic present field outside plasma column. The measurements are carried out from a set of small coils, which are located inside the vacuum chamber in the radial and poloidal direction, so we can measure magnetic field with no current attenuations produced by the penetration time of the stainless steel vacuum chamber. The magnetic probe detect a real time variation of magnetic flux passing through them. In order to obtain the magnetic field values, it is required that the electric signals coming from the magnetic probe be integrated, this operation is carried out by active circuits located between the probe signal and one oscilloscope. The integrated signals can be exhibited photographed on the oscilloscope display. (Author)

  15. On the balance of a linear plasma column confined in a transverse magnetic field

    International Nuclear Information System (INIS)

    Lehnert, B.

    1978-08-01

    The equilibrium features are investigated of a straight plasma column being confined in a purely transverse magnetic field, part of which is being generated by external conductors. Provided that stability can be secured at high beta values, the reduced transport of particles and heat in the axial direction should allow for large axial temperature gradients. It is then expected that temperatures even leading to ignition can be achieved in a pure plasma, at technically realistic column lengths. (author)

  16. HF heating of a plasma column at frequencies below the electron cyclotron frequency

    International Nuclear Information System (INIS)

    Datlov, J.; Kopecky, V.; Musil, J.; Zacek, F.; Novik, K.

    1978-02-01

    The dispersion of waves, excited by the helical structure in a plasma column and the heating of a tail of the electron distribution function is studied at frequencies below the electron plasma frequency and the electron cyclotron frequency. (author)

  17. Conditions for soft x-ray lasing action in a confined plasma column

    International Nuclear Information System (INIS)

    Suckewer, S.; Fishman, H.

    1979-09-01

    The idea of using a multi-Z (e.g., carbon, oxygen) thin plasma column as a medium for soft x-ray lasing action is presented. A plasma confined by a strong magnetic field is first heated by a CO 2 -laser, and then cools rapidly by radiation losses. This leads to a level population inversion of hydrogen-like carbon or oxygen ions. Two computational models are presented. One uses given electron temperature, T/sub e/(t), evolutions. The other uses T/sub e/(t) calculated from an energy balance equation ith CO 2 -laser beam power as a parameter. According to calculations, a total gain of G > 100 is expected for 3 → 2 and G > 10 for 4 → 2 transitions (lambda = 182 A and lambda = 135 A, respectively) for CVI ions using a CO 2 -laser beam with power approx. 5 x 10 10 W for plasma column heating

  18. Nonlinear scattering from a plasma column. I - Theory. II Special cases

    Science.gov (United States)

    Crawford, F. W.; Harker, K. J.

    1983-01-01

    The scattered signal excited by nonlinear mixing of two plane waves normally incident on an infinitely long column of plasma is investigated. A general solution is obtained for the polarization in which the electric field vectors of the waves are perpendicular to the column axis and the column is assumed to be radically inhomogeneous. This general theory is then applied to the special cases of the inhomogeneous column in the long-wavelength limit, and the homogeneous column both for the general case and in the long-wavelength limit. It is determined that dipole and quadrupole components should predominate in the polar radiation pattern for the long-wavelength case. The special case of second harmonic generation due to a single incident wave is analyzed in detail. Nonlinear scattering coefficients are computed, and the corresponding polar radiation patterns are determined. The findings of this study are employed to evaluate the feasibility of observing nonlinear scattering from meteor trails.

  19. Stability Limits and Properties of Dense Nonneutral Plasmas

    International Nuclear Information System (INIS)

    Pollock, R. E.

    2001-01-01

    Developed equipment consisted of a high magnetic field solenoid with supporting instrumentation for electron plasma confinement. The solenoid was designed and delivered in year 1. In year 2, it was mapped and the trap was created and commissioned. In parallel, an ongoing program of beam-plasma interaction studies was carried out with a lower field trap developed earlier. The trap was placed in the IUCF Coolor (an intermediate-energy electron-cooled storage ring) and the effects of the beam on the plasma were investigated, including energy and angular momentum transfer. Student projects carried out within the beam-plasma group also included development of a diagnostic with high spatial resolution, and preparation for extension of the beam-plasma interaction study to much lower beam energy. This became the principal group activity during the latter part of the project

  20. Dispersion characteristics of electromagnetic waves in dipolar (m=±1) modes travelling along a magnetized plasma column

    International Nuclear Information System (INIS)

    Benova, E.; Ghanashev, I.; Zhelyazkov, I.

    1992-01-01

    The modelling of isotropic plasma columns sustained by travelling electromagnetic waves in the dipolar mode (angular dependence exp imφ, m=±1) shows that the m=±1 modes have identical dispersion characteristics. In the presence of an external static magnetic field, however, the modes behave rather differently. This observation arose in studying the axial structures of magnetized plasma columns surrounded by vacuum and produced by travelling electromagnetic waves in the dipolar modes. We examine the propagation of electromagnetic waves along a homogeneous cold plasma column of radius R and electron number density n immersed in an axial constant magnetic field. (author) 3 refs., 3 figs

  1. Numerical investigation of three-dimensional single-species plasma equilibria on magnetic surfaces

    International Nuclear Information System (INIS)

    Lefrancois, Remi G.; Pedersen, Thomas Sunn; Boozer, Allen H.; Kremer, Jason P.

    2005-01-01

    Presented for the first time are numerical solutions to the three-dimensional nonlinear equilibrium equation for single-species plasmas confined on magnetic surfaces and surrounded by an equipotential boundary. The major-radial shift of such plasmas is found to be outward, qualitatively similar to the Shafranov shift of quasineutral plasmas confined on magnetic surfaces. However, this is the opposite of what occurs in the pure toroidal field equilibria of non-neutral plasmas (i.e., in the absence of magnetic surfaces). The effect of varying the number of Debye lengths in the plasma for the three-dimensional (3D) model is in agreement with previous 2D calculations: the potential varies significantly on magnetic surfaces for plasmas with few Debye lengths (a d ), and tends to be constant on surfaces when many Debye lengths are present (a > or approx. 10λ d ). For the case of a conducting boundary that does not conform to the outer magnetic surface, the plasma is shifted towards the conductor and the potential varies significantly on magnetic surfaces near the plasma edge. Debye shielding effects are clearly demonstrated when a nonuniform bias is applied to the boundary. Computed equilibrium profiles are presented for the Columbia Non-Neutral Torus [T. S. Pedersen, A. H. Boozer, J. P. Kermer, R. Lefrancois, F. Dahlgren, N. Pomphrey, W. Reiersen, and W. Dorland, Fusion Sci. Technol. 46, 200 (2004)], a stellarator designed to confine non-neutral plasmas

  2. Mode conversion and its utilization of degenerating surface wave modes on a plasma column

    International Nuclear Information System (INIS)

    Nonaka, S.; Akao, Y.

    1983-01-01

    Both mode conversion at degenerating points of dispersion relations for surface wave modes on a discharge plasma column and the methods for their detection and utilization are presented. Mode conversions at three degenerating points become observable by using a surface wave resonator when an azimuthal inhomogeneity of plasma is produced by a static magnetic field of about 1 G applied perpendicular to the column axis. Two of the three detected degenerating points can be utilized for an easy and exact determination of the electron density and its distribution in the discharge tube

  3. Non-Neutralizing Antibodies Directed against HIV and Their Functions

    Directory of Open Access Journals (Sweden)

    Luzia M. Mayr

    2017-11-01

    Full Text Available B cells produce a plethora of anti-HIV antibodies (Abs but only few of them exhibit neutralizing activity. This was long considered a profound limitation for the enforcement of humoral immune responses against HIV-1 infection, especially since these neutralizing Abs (nAbs are extremely difficult to induce. However, increasing evidence shows that additional non-neutralizing Abs play a significant role in decreasing the viral load, leading to partial and sometimes even total protection. Mechanisms suspected to participate in protection are numerous. They involve the Fc domain of Abs as well as their Fab part, and consequently the induced Ab isotype will be determinant for their functions, as well as the quantity and quality of the Fc-receptors (FcRs expressed on immune cells. Fc-mediated inhibitory functions, such as Ab-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, aggregation, and even immune activation have been proposed. However, as for nAbs, the non-neutralizing activities are limited to a subset of anti-HIV Abs. An improved in-depth characterization of the Abs displaying these functional responses is required for the development of new vaccination strategies, which aim to selectively trigger the B cells able to induce the right functional Ab combinations both at the right place and at the right time. This review summarizes our current knowledge on non-neutralizing functional inhibitory Abs and discusses the potential benefit of inducing them via vaccination. We also provide new insight into the roles of the FcγR-mediated Ab therapeutics in clinical trials for HIV diseases.

  4. QC operator’s nonneutral posture against musculoskeletal disorder’s (MSDs) risks

    Science.gov (United States)

    Kautsar, F.; Gustopo, D.; Achmadi, F.

    2018-04-01

    Musculoskeletal disorders refer to a gamut of inflammatory and degenerative disorders aggravated largely by the performance of work. It is the major cause of pain, disability, absenteeism and reduced productivity among workers worldwide. Although it is not fatal, MSDs have the potential to develop into serious injuries in the musculoskeletal system if ignored. QC operators work in nonneutral body posture. This cross-sectional study was condusted in order to investigate correlation between risk assessment results of QEC and body posture calculation of mannequin pro. Statistical analysis was condusted using SPSS version 16.0. Validity test, Reliability test and Regression analysis were conducted to compare the risk assessment output of applied method and nonneutral body posture simulation. All of QEC’s indicator classified as valid and reliable. The result of simple regression anlysis are back (0.3264.32), wrist/hand (4.86 >4.32) and neck (1.298 <4.32). Result of this study shows that there is an influence between nonneutral body posture of the QC operator during work with risk of musculoskeletal disorders. The potential risk of musculoskeletal disorders is in the shoulder/arm and wrist/hand of the QC operator, whereas the back and neck are not affected.

  5. Modulation of ionization in the plasma column of an optical discharge

    International Nuclear Information System (INIS)

    Nastoyashchii, A.F.

    1981-01-01

    Stability of the ionization in the plasma column of an optical discharge is discussed. It is shown that a plasma filament formed by a long laser spike under optical discharge conditions may break up into a chain of bright luminous layers oriented in the direction of propagation of a laser beam and characterized by a higher gas ionization (''optical striations''). A nonlinear formulation of the problem is used to find the depth of modulation of the gas ionization

  6. Influence of continuously-varing profile on the diocotron instability in a non neutral plasma column

    International Nuclear Information System (INIS)

    Asgary, H. R.; Maraghehechi, Behrooz; Rafii, Mahboobeh

    2003-01-01

    In this paper we investigate the theoretical method related to density profile effect on diocotron instability in nonrelativistic state in non neutral plasma column. At first we introduce non neutral plasma and diocotron instability then we extract instability equation and we will investigate plasma stability with special profile density

  7. Radioimmunoassay of glandular kallikrein in human plasma after partial purification by immunoaffinity column

    International Nuclear Information System (INIS)

    Nishimura, Kazutaka; Inoue, Yoshikazu; Kokubu, Tatsuo

    1987-01-01

    Glandular kallikrein in human plasma was partially purified by immunoaffinity column and was measured by a radioimmunoassay (RIA). Plasma was diluted with an equal volume of 10 mmol/l sodium phosphate buffer, pH 7.4, containing 0.9% NaCl (PBS) and was applied to an immunoaffinity column from which glandular kallikrein was eluted with 3 mol/l NaSCN (20 ml). The enzymic fraction was concentrated with an Amicon PM 10 filter and dialyzed against PBS. The final recovery of the enzyme was 51.6 ± 1.6%, determined by using [ 125 I]kallikrein. The usable range of the standard curve covered 2.5-100 ng/tube. The coefficient of variation within the series was 5.9%, and the coefficient of variation between the series was 7.6%. In healthy controls, the plasma content of glandular kallikrein was 1.36 ± 0.39 ng/ml. In patients with acute pancreatitis, the plasma concentration was 8.02 ± 6.15 ng/ml, significantly different from the control group. (Auth.)

  8. Hybrid 3D model for the interaction of plasma thruster plumes with nearby objects

    Science.gov (United States)

    Cichocki, Filippo; Domínguez-Vázquez, Adrián; Merino, Mario; Ahedo, Eduardo

    2017-12-01

    This paper presents a hybrid particle-in-cell (PIC) fluid approach to model the interaction of a plasma plume with a spacecraft and/or any nearby object. Ions and neutrals are modeled with a PIC approach, while electrons are treated as a fluid. After a first iteration of the code, the domain is split into quasineutral and non-neutral regions, based on non-neutrality criteria, such as the relative charge density and the Debye length-to-cell size ratio. At the material boundaries of the former quasineutral region, a dedicated algorithm ensures that the Bohm condition is met. In the latter non-neutral regions, the electron density and electric potential are obtained by solving the coupled electron momentum balance and Poisson equations. Boundary conditions for both the electric current and potential are finally obtained with a plasma sheath sub-code and an equivalent circuit model. The hybrid code is validated by applying it to a typical plasma plume-spacecraft interaction scenario, and the physics and capabilities of the model are finally discussed.

  9. Propagation and diffusion of a plasma column in a magnetic field; Propagation et diffusion d'une colonne de plasma dans un champ magnetique

    Energy Technology Data Exchange (ETDEWEB)

    Bottiglioni, F; Coutant, J; Gadda, E; Prevot, F [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1966-12-01

    A plasma column is created in a magnetic field by longitudinal diffusion from a low-pressure pulsed discharge in hydrogen. Depending on the discharge conditions, two regimes are obtained in which the gas pumping speed has a different effect upon the plasma density in the column. Calculations are presented which can explain this effect by a difference in the transverse diffusion coefficient. (authors) [French] On forme une colonne de plasma dans un champ magnetique par diffusion longitudinale a partir d'une decharge puisee dans l'hydrogene a basse pression. Selon les conditions de la decharge on observe deux regimes differents pour lesquels le pompage du gaz neutre a un effet different sur la densite resultante du plasma dans la colonne. On presente des calculs qui peuvent expliquer cet effet par une difference dans la diffusion transversale du plasma. (auteurs)

  10. Evolution of transverse instability in a hollow cylindrical weakly-ionized plasma column

    International Nuclear Information System (INIS)

    Kuedyan, H.M.

    1978-01-01

    Having observed formation of plasma striations in an Electron Cyclotron Resonance Heating (ECRH) device, we have studied the conditions under which the hollow cylindrical plasma columns would develop into striations. We first present the observed conditions of the hollow cylindrical plasma which would develop into plasma striations, the measured characteristics of the transverse oscillations and a simple small signal model for a transverse instability in a weakly-ionized hollow cylindrical plasma. This linearized model, which assumes flowing cold ion fluid (T/sub i/ approximately < 0.1 eV) in warm electron fluid (T/sub e/ approximately 1 eV) and background neutrals, reveals a transverse flute-type electrostatic instability whose characteristics are in qualitative and quantitative agreement with the measured values of the oscillations in our experiment

  11. Laser beam trapping and propagation in cylindrical plasma columns

    International Nuclear Information System (INIS)

    Feit, M.D.; Fleck, J.A. Jr.

    1976-01-01

    An analysis of the scheme to heat magnetically confined plasma columns to kilovolt temperatures with a laser beam requires consideration of two propagation problems. The first question to be answered is whether stable beam trapping is possible. Since the laser beam creates its own density profile by heating the plasma, the propagation of the beam becomes a nonlinear phenomenon, but not necessarily a stable one. In addition, the electron density at a given time depends on the preceding history of both the medium and the laser pulse. A self-consistent time dependent treatment of the beam propagation and the medium hydrodynamics is consequently required to predict the behavior of the laser beam. Such calculations have been carried out and indicate that propagation of a laser beam in an initially uniform plasma can form a stable filament which alternately focuses and defocuses. An additional question that is discussed is whether diffractive losses associated with long propagation paths are significant

  12. Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas

    2015-01-01

    A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized high-speed cameras. Whereas the data analysis for such systems has previously been performed in 2D (analyzing......, gives more realistic insight into the convection cooling process. Additionally, with the determination of the 3D slip velocity and the 3D length of the plasma column, we give more accurate estimates for the drag force, the electric field strength, the power per unit length, and the radius...

  13. Boundary asymptotics for a non-neutral electrochemistry model with small Debye length

    Science.gov (United States)

    Lee, Chiun-Chang; Ryham, Rolf J.

    2018-04-01

    This article addresses the boundary asymptotics of the electrostatic potential in non-neutral electrochemistry models with small Debye length in bounded domains. Under standard physical assumptions motivated by non-electroneutral phenomena in oxidation-reduction reactions, we show that the electrostatic potential asymptotically blows up at boundary points with respect to the bulk reference potential as the scaled Debye length tends to zero. The analysis gives a lower bound for the blow-up rate with respect to the model parameters. Moreover, the maximum potential difference over any compact subset of the physical domain vanishes exponentially in the zero-Debye-length limit. The results mathematically confirm the physical description that electrolyte solutions are electrically neutral in the bulk and are strongly electrically non-neutral near charged surfaces.

  14. Waves and instabilities in noneutral plasmas

    International Nuclear Information System (INIS)

    Davidson, R.C.

    1989-01-01

    This paper presents a survey of the equilibrium, stability and collective oscillation properties of magnetically-confined nonneutral plasmas. Emphasis is placed on summarizing several of the technical advances that have occurred in both theory and experiment since the early 1970's. 97 refs., 26 figs

  15. Soft x-ray laser gain measurements in a recombining plasma column

    International Nuclear Information System (INIS)

    Suckewer, S.; Skinner, C.H.; Milchberg, H.; Keane, C.; Voorhees, D.

    1985-03-01

    An enhancement of approx. 100 of stimulated emission over spontaneous emission of the CVI 182 A line (one-pass gain approx. = 6.5) was measured in a recombining, magnetically confined plasma column by two independent techniques using intensity calibrated XUV monochromators. Additional confirmation that the enhancement was due to stimulated emission has been obtained with a soft x-ray mirror

  16. Nonneutral plasma diagnostic commissioning for the ALPHA Antihydrogen experiment

    Science.gov (United States)

    Konewko, S.; Friesen, T.; Tharp, T. D.; Alpha Collaboration

    2017-10-01

    The ALPHA experiment at CERN creates antihydrogen by mixing antiproton and positron plasmas. Diagnostic measurements of the precursor plasmas are performed using a diagnostic suite, colloquially known as the ``stick.'' This stick has a variety of sensors and is able to move to various heights to align the desired diagnostic with the beamline. A cylindrical electrode, a faraday cup, an electron gun, and a microchannel-plate detector (MCP) are regularly used to control and diagnose plasmas in ALPHA. We have designed, built, and tested a new, upgraded stick which includes measurement capabilities in both beamline directions.

  17. Lack of protection following passive transfer of polyclonal highly functional low-dose non-neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Dugast

    Full Text Available Recent immune correlates analysis from the RV144 vaccine trial has renewed interest in the role of non-neutralizing antibodies in mediating protection from infection. While neutralizing antibodies have proven difficult to induce through vaccination, extra-neutralizing antibodies, such as those that mediate antibody-dependent cellular cytotoxicity (ADCC, are associated with long-term control of infection. However, while several non-neutralizing monoclonal antibodies have been tested for their protective efficacy in vivo, no studies to date have tested the protective activity of naturally produced polyclonal antibodies from individuals harboring potent ADCC activity. Because ADCC-inducing antibodies are highly enriched in elite controllers (EC, we passively transferred highly functional non-neutralizing polyclonal antibodies, purified from an EC, to assess the potential impact of polyclonal non-neutralizing antibodies on a stringent SHIV-SF162P3 challenge in rhesus monkeys. Passive transfer of a low-dose of ADCC inducing antibodies did not protect from infection following SHIV-SF162P3 challenge. Passively administered antibody titers and gp120-specific, but not gp41-specific, ADCC and antibody induced phagocytosis (ADCP were detected in the majority of the monkeys, but did not correlate with post infection viral control. Thus these data raise the possibility that gp120-specific ADCC activity alone may not be sufficient to control viremia post infection but that other specificities or Fc-effector profiles, alone or in combination, may have an impact on viral control and should be tested in future passive transfer experiments.

  18. Finite length thermal equilibria of a pure electron plasma column

    International Nuclear Information System (INIS)

    Prasad, S.A.; O'Neil, T.M.

    1979-01-01

    The electrons of a pure electron plasma may be in thermal equilibrium with each other and still be confined by static magnetic and electric fields. Since the electrons make a significant contribution to the electric field, only certain density profiles are consistent with Poisson's equation. The class of such distributions for a finite length cylindrical column is investigated. In the limit where the Debye length is small compared with the dimensions of the column, the density is essentially constant out to some surface of revolution and then falls off abruptly. The falloff in density is a universal function when measured along the local normal to the surface of revolution and scaled in terms of the Debye length. The solution for the shape of the surface of revolution is simplified by passage to the limit of zero Debye length

  19. NON-NEUTRALIZED ELECTRIC CURRENT PATTERNS IN SOLAR ACTIVE REGIONS: ORIGIN OF THE SHEAR-GENERATING LORENTZ FORCE

    International Nuclear Information System (INIS)

    Georgoulis, Manolis K.; Titov, Viacheslav S.; Mikić, Zoran

    2012-01-01

    Using solar vector magnetograms of the highest available spatial resolution and signal-to-noise ratio, we perform a detailed study of electric current patterns in two solar active regions (ARs): a flaring/eruptive and a flare-quiet one. We aim to determine whether ARs inject non-neutralized (net) electric currents in the solar atmosphere, responding to a debate initiated nearly two decades ago that remains inconclusive. We find that well-formed, intense magnetic polarity inversion lines (PILs) within ARs are the only photospheric magnetic structures that support significant net current. More intense PILs seem to imply stronger non-neutralized current patterns per polarity. This finding revises previous works that claim frequent injections of intense non-neutralized currents by most ARs appearing in the solar disk but also works that altogether rule out injection of non-neutralized currents. In agreement with previous studies, we also find that magnetically isolated ARs remain globally current-balanced. In addition, we confirm and quantify the preference of a given magnetic polarity to follow a given sense of electric currents, indicating a dominant sense of twist in ARs. This coherence effect is more pronounced in more compact ARs with stronger PILs and must be of sub-photospheric origin. Our results yield a natural explanation of the Lorentz force, invariably generating velocity and magnetic shear along strong PILs, thus setting a physical context for the observed pre-eruption evolution in solar ARs.

  20. Formation of electrostatic double-layers and electron-holes in a low pressure mercury plasma column

    International Nuclear Information System (INIS)

    Petraconi, G; Maciel, Homero S

    2003-01-01

    Experimental studies of the formation of electrostatic double layers (DLs) and electron-holes (e-holes) are reported. The measurements were performed in the positive column of a mercury arc discharge operating in the low-pressure range of (2.0-14.0) x 10 -2 Pa with current density in the range of (3.0-8.0) x 10 3 A m -2 . Stable and unstable modes of the discharge were identified as the current was gradually increased, keeping constant the vapour pressure. The discharge remains stable until a critical current from which a slight increase of the current leads to an unstable regime characterized by high discharge impedance and strong oscillations. This mode ceased after a DL was formed in the plasma column. To induce the DL formation and to transport it smoothly along the discharge column, a low intensity B-field (7-10) x 10 -3 T produced by a movable single coil was used. The B-field locally increases the electron current density and makes the DL form at the centre of the magnetic constriction where it remained at rest. Electrostatic potential structures compatible with ordinary DLs and multiple-layers could be formed in the plasma column by dealing with the combined effects of the operational parameters of the discharge. It is noticeable that a pure e-hole, which is a symmetric triple-layer having a bell shape potential profile, could easily be formed by means of this experimental technique. A partial kinetic description, based on the space charge structure derived from an experimental e-hole, is presented in order to infer the charged particle populations that could contribute to the space charge of the e-hole. Evidence is shown that strong e-hole formation might be driven by an ion beam, therefore it could not be formed in isolation since its formation requires a nearby ion accelerating potential structure. Probe measurements of the plasma properties, at various radial positions of the stable positive column, are also presented. In the stable mode, prior to

  1. Numerical Simulation of Dual-Channel Communication of Column Plasma Antenna Excited by a Surface Wave

    International Nuclear Information System (INIS)

    Duanmu Gang; Zhao Changming; Liang Chao; Xu Yuemin

    2014-01-01

    This paper focuses on the application of plasma as wireless antenna. In order to reveal the radiation characteristics of column plasma antenna, we chose the finite-difference time-domain (FDTD) numerical analysis method to simulate radiation impedance and efficiencies of each channel for a few sets of plasma densities and plasma collision frequencies. Simulation results demonstrate that a plasma antenna shares similar characteristics with a metallic antenna in radiation impedance and efficiency of each channel when an appropriate setting is adopted. Unlike a metallic antenna, a plasma antenna is capable of realizing such functions as dynamic reconfiguration, digital control and dual-channel communication. Thus it is possible to carry out dual-channel communication by plasma antenna, indicating a new path for modern intelligent communication. (plasma technology)

  2. Radio-frequency wave excitation and damping on a high β plasma column

    International Nuclear Information System (INIS)

    Meuth, H.

    1984-01-01

    Azimuthally symmetric (m = 0) radio-frequency (RF) waves for zero and for finite axial wave number k/sub z/ are investigated on the High BETA Q Machine, a two-meter, 20 cm-diameter, low-compression linear theta pinch (T greater than or equal to 200 eV, n approx. = 10 15 cm -3 ) fast rising (0.4 μs) compression field. The (k/sub z/ = 0) modes occur spontaneously following the implosion phase of the discharge. A novel 100-MW 1 to 1.3 MHz, short wavelength current drive excites the plasma column in the vicinity of the lowest fast magnetoacoustic mode at various filling pressures. This current drive is designed as an integral part of the compression coil, which is segmented with a 20-cm axial wavelength (k/sub z/ = 0.314 cm -1 ). The electron density oscillations along major and minor chords at various positions are measured by interferometry perpendicular to the pinch axis. The oscillatory radial magnetic field component between pinch wall and hot plasma edge is measured by probes. Phases, amplitudes and radial mode structure are studied for the free (k = 0) modes and the externally driven (k does not equal 0) modes for various filling pressures of deuterium. The energy deposition from the externally driven RF wave leads to a radial expansion of the plasma column, as observed by axial interferometry and by excluded flux measurements

  3. A column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry method to determine anandamide and 2-arachidonoylglycerol in plasma samples.

    Science.gov (United States)

    Marchioni, Camila; de Souza, Israel Donizeti; Grecco, Caroline Fernandes; Crippa, José Alexandre; Tumas, Vitor; Queiroz, Maria Eugênia Costa

    2017-05-01

    This study reports a fast, sensitive, and selective column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to determine the endocannabinoids (eCBs), anandamide (AEA), and 2-arachidonoylglycerol (2-AG) in plasma samples. This bidimensional system used a restricted access media column (RP-8 ADS, 25 mm × 4 mm × 25 μM) in the first dimension and a core-shell Kinetex C18 (100 mm × 2, 1.7 mm × 1 μM) column in the second dimension, followed by detection in a mass spectrometer triple quadrupole (multiple reactions monitoring mode) operating in the positive mode. RP-8 ADS was used for trace enrichment of eCBs (reverse phase partitioning) and macromolecular matrix size exclusion; the core-shell column was used for the chromatographic separation. The column switching UHPLC-MS/MS method presented a linear range spanning from 0.1 ng mL -1 (LOQ) to 6 ng mL -1 for AEA and from 0.04 ng mL -1 (LOQ) to 10 ng mL -1 for 2-AG. Excluding the LLOQ values, the precision assays provided coefficients of variation lower than 8% and accuracy with relative standard error values lower than 14%. Neither carryover nor matrix effects were detected. This high-throughput column switching method compared to conventional methods is time saving as it involves fewer steps, consumes less solvent, and presents lower LLOQ. The column switching UHPLC-MS/MS method was successfully applied to determine AEA and 2-AG in plasma samples obtained from Alzheimer's disease patients. Graphical abstract A column switching ultra high-performance liquid chromatography-tandem mass spectrometry method using RP-8 ADS column and core shell column to determine endocannabinoids in plasma samples.

  4. Plasma pressure in the discharge column of the Novillo Tokamak

    International Nuclear Information System (INIS)

    Gaytan G, E.

    1995-01-01

    The design and construction of an acquisition system for the measurement of the plasma pressure in the Novillo Tokamak is described in detail. The system includes a high voltage ramp generator, a hardware and a software interface with a personal computer. It is used to determine experimentally the variations of the pressure in the plasma column in the cleaning and main discharges. The measurement of the pressure is made with a Pirani sensor adapted to the acquisition hardware and synchronized with the discharge in the plasma. The software is made in object oriented programming as a graphic interface designed to be used easily. It controls the acquisition, records the data, displays in graphic form the results and save the measurements. The graphic interface is a building block that can be used in different acquisition tasks. The ramp generator can deliver a signal of 200 V peak to peak with a current of 200 m A and offset control. The acquisition time is 2.5 μ s for every measurement, 8192 measurements can be stored in the acquisition board for every discharge. (Author)

  5. Magnetic spires for the detection of the position of the plasma column in a Tokamak (linear approximation)

    International Nuclear Information System (INIS)

    Colunga S, S.

    1990-07-01

    In this report the simplified analysis of a method to detect the movement of the plasma column of a tokamak in the vertical direction and of the biggest radius is given. The peculiar case of the Tokamak Novillo of the Plasma Physics Laboratory of the ININ is studied. (Author)

  6. Streamlined Darwin simulation of nonneutral plasmas

    International Nuclear Information System (INIS)

    Hewett, D.W.; Boyd, J.K.

    1987-01-01

    Efficient, new algorithms that require less formal manipulation than previous implementations have been formulated for the numerical solution of the Darwin model. These new procedures reduce the effort required to achieve some of the advantages that the Darwin model offers. Because the Courant--Friedrichs--Lewy stability limit for radiation modes is eliminated, the Darwin model has the advantage of a substantially larger time-step. Further, without radiation modes, simulation results are less sensitive to enhanced particle fluctation noise. We discuss methods for calculating the magnetic field that avoid formal vector decomposition and offer a new procedure for finding the inductive electric field. This procedure avoids vector decomposition of plasma source terms and circumvents some source gradient issues that slow convergence. As a consequence, the numerical effort required for each of the field time-steps is reduced, and more importantly, the need to specify several nonintuitive boundary conditions is eliminated. copyright 1987 Academic Press, Inc

  7. Self-organization observed in either fusion or strongly coupled plasmas

    International Nuclear Information System (INIS)

    Himura, Haruhiko; Sanpei, Akio

    2011-01-01

    If self-organization happens in the fusion plasma, the plasma alters its shape by weakening the confining magnetic field. The self-organized plasma is stable and robust, so its configuration is conserved even during transport in asymmetric magnetic fields. The self-organization of the plasma is driven by an electrostatic potential. Examples of the plasma that has such strong potential are non-neutral plasmas of pure ions or electrons and dusty plasmas. In the present paper, characteristic phenomena of strongly coupled plasmas such as particle aggregation and formation of the ordered structure are discussed. (T.I.)

  8. Modelling of a plasma column sustained by a travelling circularly polarized electromagnetic wave (m=1 mode) in the presence of a constant axial magnetic field

    International Nuclear Information System (INIS)

    Benova, E.; Staikov, P.; Zhelyazkov, I.

    1992-01-01

    A set of equations modelling a low-pressure plasma column sustained by a travelling electromagnetic wave in the dipolar mode in the presence of a constant external magnetic field is presented. It is shown that, from a practical point of view, only the m = 1 mode (the right-hand-polarized wave) can sustain plasma columns in a wide region of gas-discharge conditions: plasma radius R, wave frequency ω, magnetic field B 0 and low pressures, irrespective of the nature of the gas. The main result of this study is that the magnetic field makes it possible to sustain a plasma column for values of σ smaller than σ cr = 0.3726, below which, in the absence of a magnetic field, the dipolar wave cannot produce a plasma. Moreover, at a fixed wave power, the magnetic field - in contrast with the case of plasma columns sustained by azimuthally symmetric waves - increases the plasma density and its axial gradient. The limit of an infinite external magnetic field (Ω → ∞) is also considered. A three-dimensional wave structure is obtained, and it indicates that the wave can be a generalized surface mode, a pure surface or a pseudosurface one. (author)

  9. Cylindrical stationary striations in surface wave produced plasma columns of argon

    Science.gov (United States)

    Kumar, Rajneesh; Kulkarni, Sanjay V.; Bora, Dhiraj

    2007-12-01

    Striations are a good example of manifestation of a glow discharge. In the present investigation, stationary striations in the surface wave produced plasma column are formed. Physical parameters (length, number, etc.) of such striations can be controlled by operating parameters. With the help of bifurcation theory, experimental results are explained by considering two-step ionization in the surface wave discharge mechanism in argon gas. It is also observed that the bifurcation parameter is a function of input power, working pressure, and tube radius.

  10. Plasma column development in the CO2 laser-heated solenoid

    International Nuclear Information System (INIS)

    Tighe, W.; Offenberger, A.A.; Capjack, C.E.

    1987-01-01

    Axial and radial plasma dynamics in the CO 2 laser-heated solenoid have been studied experimentally and numerically. The axial behavior is found to be well described by a self-regulated bleaching wave model. The radial expansion is found to be strongly dependent on the focusing ratio of the input laser beam. With a fast focus ( f/5), the early radial expansion rate is twice that found with a slower focusing arrangement ( f/15). The faster focusing ratio also results in a significantly wider plasma column. On the other hand, no significant dependence of f/number on the axial propagation was found. A finite ionization time and the rapid formation of a density minimum on axis are observed and verify earlier experimental results. Detailed comparisons are made with a 2-D magnetohydrodynamic (MHD) and laser propagation code. The axial and radial plasma behavior and, in particular, the dependence of the radial behavior on the focal ratio of the laser are reasonably well supported by the simulation results. Computational results are also in good agreement with experimental measurements of temperature and density using stimulated scattering (Brillouin, Raman) and interferometry diagnostic techniques

  11. A SINGLE-COLUMN PROCEDURE ON BOND ELUT CERTIFY FOR SYSTEMATIC TOXICOLOGICAL ANALYSIS OF DRUGS IN PLASMA AND URINE

    NARCIS (Netherlands)

    CHEN, XH; WIJSBEEK, J; FRANKE, JP; DEZEEUW, RA

    A single-column solid-phase extraction procedure was developed for the screening of acidic, neutral, and basic drugs from plasma. The recoveries of all 25 tested drugs exceeded 82%. After the plasma had been diluted with phosphate buffer (pH 6.0), the drugs were extracted using a single Bond Elut

  12. Ideal MHD equilibrium of a weakly toroidal plasma column with elongated cross-section

    International Nuclear Information System (INIS)

    Heesch, E.J.M. van; Schuurman, W.

    1980-07-01

    Solutions are obtained of the ideal MHD equations describing the equilibrium of a weakly toroidal plasma with an elliptic cross-section surrounded by a force-free magnetic field with constant ratio between current density and magnetic field strength. The force-free field parameter causes the stagnation points to recede along the major axis of the ellipse. Above a certain value of the force-free field parameter, stagnation points do not exist, so that the compression ratio of the plasma column is no longer limited. The analysis was carried out to first order in the force-free field parameter as well as to second order for an estimate of the error

  13. Plasma column displacement measurements by modified Rogowski sine-coil and Biot-Savart/magnetic flux equation solution on IR-T1 tokamak

    International Nuclear Information System (INIS)

    Razavi, M.; Mollai, M.; Khorshid, P.; Nedzelskiy, I.; Ghoranneviss, M.

    2010-01-01

    The modified Rogowski sine-coil (MRSC) has been designed and implemented for the plasma column horizontal displacement measurements on small IR-T1 tokamak. MRSC operation has been examined on test assembly and tokamak. Obtained results show high sensitivity to the plasma column horizontal displacement and negligible sensitivity to the vertical displacement; linearity in wide, ±0.1 m, range of the displacements; and excellent, 1.5%, agreement with the results of numerical solution of Biot-Savart and magnetic flux equations.

  14. Centrifugal Separation and Equilibration Dynamics in an Electron-Antiproton Plasma

    International Nuclear Information System (INIS)

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Bertsche, W.; Butler, E.; Charlton, M.; Deller, A.; Eriksson, S.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der; Cesar, C. L.; Friesen, T.

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  15. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    CERN Document Server

    Andresen, G B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Deller, A; Eriksson, S; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Gutierrez, A; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  16. Equilibrium and dynamics of uniform density ellipsoidal non-neutral plasmas

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1993-01-01

    When a single-species plasma is confined in a harmonic Penning trap at cryogenic temperature, the thermal equilibrium is approximately a uniform density spheroid (ellipsoid of revolution). Normal modes corresponding to quadrupole excitations of this plasma have recently been measured. In this paper, nonlinear equations of motion are derived for these quadrupole oscillations. For large amplitudes, the oscillations deform a spheroidal plasma into a triaxial ellipsoid with time-dependent shape and orientation. The integrals of the motion are found and the cylindrically symmetric finite-amplitude oscillations of a spheroid are studied. An analysis of all possible ellipsoidal equilibria is also carried out. New equilibria are discovered which correspond to finite-amplitude versions of the noncylindrically symmetric linear quadrupole oscillations. The equilibria are shown to fall into two classes in which the ellipsoids are either tilted or aligned with respect to the magnetic field. Some of these equilibria have densities well above the Brillouin limit

  17. The influence of an external magnetic axial field on the autocompression of a plasma column

    International Nuclear Information System (INIS)

    Zoler, D.

    1979-01-01

    The results of theoretical research on the autocompression of a plasma column under the influence of its own azimuthal field, in the presence of an external magnetic axial field are presented in this paper. Focussed plasma installations are important both for the fundamental researches which can be undertaken on great density and high temperature plasma and for their possible applications since they can be used as sources of neutrons, Roentgen radiations and to obtain heavy ions. The important parameters of plasma have been studied comparatively in the presence or absence of the external magnetic axial field by means of a method of numerical simulation of phenomena from focussed plasma in a complex MHD system taking into account the dissipative and transport phenomena. The numerical data used in chapter 5 are in agreement with the parameters of the experimental installation produced at IFTAR-Bucharest, which have been indicated to us by the members of the focussed plasma staff. (author)

  18. Research briefing on contemporary problems in plasma science

    International Nuclear Information System (INIS)

    1991-01-01

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

  19. Differential coulometric oxidation following post column-switching high pressure liquid chromatography for fluorescence measurement of unmetabolized folic acid in human plasma.

    Science.gov (United States)

    Bailey, Steven W; Ayling, June E

    2013-11-08

    Although many countries have fortified their grain supplies with folic acid (FA) to decrease the incidence of neural tube defects, others have not due to concerns that this synthetic folate might have some adverse effects. Persistent unmetabolized FA has been found even in plasma from fasted subjects. To facilitate measurement of low levels of folic acid in human plasma, post-column coulometric oxidative cleavage was used to convert poorly fluorescent FA into a highly fluorescent compound determined to be 6-formyl-pterin. To minimize sample work-up and maximize recovery, column-switching HPLC transferred a window of eluate containing the FA from the first column (C8) onto a second column (phenyl-hexyl). The pH of two mobile phases were adjusted to be above and then below a pK of the FA α-carboxyl group, thus promoting separation from compounds coeluting from the C8-column. This permitted sample preparation using only a simple high recovery protein precipitation. Definitive identification of FA in human plasma was accomplished by duplicate injections of sample with the electrochemical voltage set above and below its half-potential. The LOD (S/N=3) was 0.10 nM. The intra- and inter-assay CV's were 2.3% and 5%, respectively. Comparison of these results with those obtained by HPLC/MS/MS with stable isotope internal standard showed a slope of 1.00 ± 0.019. This simple, sensitive, and repeatable assay facilitates a more thorough investigation of the response of various human populations to folic acid intake. Post-column differential coulometric electrochemistry can expand the variety of compounds amenable to fluorescence detection. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Space-charge waves in magnetized and collisional quantum plasma columns confined in carbon nanotubes

    International Nuclear Information System (INIS)

    Bagheri, Mehran; Abdikian, Alireza

    2014-01-01

    We study the dispersion relation of electrostatic waves propagating in a column of quantum magnetized collisional plasma embraced completely by a metallic single-walled carbon nanotubes. The analysis is based on the quantum linearized hydrodynamic formalism of collective excitations within the quasi-static approximation. It is shown when the electronic de Broglie's wavelength of the plasma is comparable in the order of magnitude to the radius of the nanotube, the quantum effects are quite meaningful and our model anticipates one acoustical and two optical space-charge waves which are positioned into three propagating bands. With increasing the nanotube radius, the features of the acoustical branch remain unchanged, yet two distinct optical branches are degenerated and the classical behavior is recovered. This study might provide a platform to create new finite transverse cross section quantum magnetized plasmas and to devise nanometer dusty plasmas based on the metallic carbon nanotubes in the absence of either a drift or a thermal electronic velocity and their existence could be experimentally examined

  1. Relativistic electron beam - plasma interaction with intense self-fields

    International Nuclear Information System (INIS)

    Davidson, R.C.

    1984-01-01

    The major interest in the equilibrium, stability and radiation properties of relativistic electron beams and in beam-plasma interactions originates from several diverse research areas. It is well known that a many-body collection of charged particles in which there is not overall charge neutrality and/or current neutrality can be characterized by intense self-electric fields and/or self-magnetic fields. Moreover, the intense equilibrium self-fields associated with the lack of charge neutrality and/or current neutrality can have a large effect on particle trajectories and on detailed equilibrium and stability behavior. The main emphasis in Sections 9.1.2-9.1.5 of this chapter is placed on investigations of the important influence of self-fields on the equilibrium and stability properties of magnetically confined electron beam-plasma systems. Atomic processes and discrete particle interactions (binary collisions) are omitted from the analysis, and collective processes are assumed to dominate on the time and length scales of interest. Moreover, both macroscopic (Section 9.1.2) and kinetic (Sections 9.1.3-9.1.5) theoretical models are developed and used to investigate equilibrium and stability properties in straight cylindrical geometry. Several of the classical waves and instabilities characteristic of nonneutral plasmas and beam-plasma systems are analyzed in Sections 9.1.2-9.1.5, including stable surface oscillation on a nonneutral electron beam, the ion resonance instability, the diocotron instability, two-stream instabilities between beam electrons and plasma electrons and between beam electrons and plasma ions, the filamentation instability, the modified two-stream instability, etc

  2. Using numerical simulations to extract parameters of toroidal electron plasmas from experimental data

    DEFF Research Database (Denmark)

    Ha, B. N.; Stoneking,, M. R.; Marler, Joan

    2009-01-01

    Measurements of the image charge induced on electrodes provide the primary means of diagnosing plasmas in the Lawrence Non-neutral Torus II (LNT II) [Phys. Rev. Lett. 100, 155001 (2008)]. Therefore, it is necessary to develop techniques that determine characteristics of the electron plasma from......, as in the cylindrical case. In the toroidal case, additional information about the m=1 motion of the plasma can be obtained by analysis of the image charge signal amplitude and shape. Finally, results from the numerical simulations are compared to experimental data from the LNT II and plasma characteristics...

  3. Drift resonance in high density non-neutral plasmas

    International Nuclear Information System (INIS)

    Kaup, D.J.

    2006-01-01

    Theoretical studies of the operation of crossed-field electron vacuum devices such as magnetrons and crossed-field amplifiers (CFA) have usually centered on their initial growth, taking this as an indication of their operating modes. In such an analysis one solves the equations for the density profile, the operating frequency, the growth rate, and other features of these devices. What one really obtains then are only the conditions for the device to turn on. The dominant interaction in this stage is a Rayleigh-type instability which initiates a quasilinear diffusion process whereby the electron density profile redistributes itself into a profile which will be in equilibrium with the ponderomotive-like forces produced by the growing rf fields. Eventually the rf fields will saturate and an operating device will settle into a stationary operating regime. This stage of a device's operation is called the ''saturation stage.'' This latter stage involves a different set of physical interactions from the initiation stage. No longer is there a growth rate; rather the rf amplitudes have saturated and as a result, the ponderomotive-like forces have also vanished along with the quasilinear diffusion. In this saturation stage, we find that new rf modes appear. In fact, there are a total of five rf modes, two of which are the usual slow modes of the initiation stage, and three of which have fast oscillations in the vertical direction. One fast mode corresponds to a drift plasma oscillation while the other two fast modes are drift cyclotron modes. In this paper, we will describe how the drift plasma oscillation interacts and couples with the slow rf modes at the diocotron resonance

  4. Period doubling on a non-neutral magnetized electron beam

    International Nuclear Information System (INIS)

    Boswell, R.W.

    1984-01-01

    Low frequency oscillations on a non-neutral magnetized electron beam of very low density are investigated. A perturbation analysis of the slow mode of the rigid rotator equilibrium is developed to illustrate the nature of large amplitude fundamental mode oscillations. The results of this theoretical analysis show two important characteristics: firstly, as the perturbation amplitude is increasedthe waveform ceases to be purely sinusoidal and shows period doubling. Secondly, above a certain threshold, all harmonics of the wave grow and the wave breaks. The results of the former are compared with a simple electron beam experiment and are found to be in good qualitative agreement

  5. Theory of electrostatic fluid modes in a cold spheroidal non-neutral plasma

    International Nuclear Information System (INIS)

    Dubin, D.H.E.

    1991-01-01

    The normal modes of a magnetized spheroidally shaped pure ion plasma have recently been measured. Here the theory of these modes is presented. Although one might expect that a numerical solution is required (because the plasma dielectric is anisotropic and the plasma is inhomogeneous), the problem is actually separable in an unusual coordinate system. The result is a simple electrostatic fluid dispersion relation for modes in a cloud of any spheroidal shape

  6. Fractionation separation of human plasma proteins using HPLC with a homemade iron porphyrin based monolithic column.

    Science.gov (United States)

    Zhang, Doudou; Zhao, Yu; Lan, Dandan; Pang, Xiaomin; Bai, Ligai; Liu, Haiyan; Yan, Hongyuan

    2017-11-15

    In this work a polymer monolithic column was fabricated within the confines of a stainless steel column (50×4.6mm i.d.) via radical polymerization by using iron porphyrin and butyl methacrylate as co-monomers, ethylene glycol dimethacrylate as crosslinking agent, ethylene glycol, isopropyl alcohol and N, N-dimethylformamide as tri-porogens, benzoyl peroxide and N,N-dimethylaniline as initiators. The resulting monolithic column was characterized by elemental analysis, scanning electron microscopy, nitrogen adsorption BET surface area, and mercury intrusion porosimetry, respectively. Results showed that the homemade monolith occupied relatively uniform pore structure, low back pressure, and enhanced selectivity for proteins in complex bio-samples. The present work described a simple and efficient method for "fractionation separation" of human plasma proteins, and it is a promising separation method for complex bio-samples in proteomic research. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Gyrokinetic-water-bag modeling of low-frequency instabilities in a laboratory magnetized plasma column

    Science.gov (United States)

    Gravier, E.; Klein, R.; Morel, P.; Besse, N.; Bertrand, P.

    2008-12-01

    A new model is presented, named collisional-gyro-water-bag (CGWB), which describes the collisional drift waves and ion-temperature-gradient (ITG) instabilities in a plasma column. This model is based on the kinetic gyro-water-bag approach recently developed [P. Morel et al., Phys. Plasmas 14, 112109 (2007)] to investigate ion-temperature-gradient modes. In CGWB electron-neutral collisions have been introduced and are now taken into account. The model has been validated by comparing CGWB linear analysis with other models previously proposed and experimental results as well. Kinetic effects on collisional drift waves are investigated, resulting in a less effective growth rate, and the transition from collisional drift waves to ITG instability depending on the ion temperature gradient is studied.

  8. Coherent structures and turbulence evolution in magnetized non-neutral plasmas

    Science.gov (United States)

    Romé, M.; Chen, S.; Maero, G.

    2018-01-01

    The evolution of turbulence of a magnetized pure electron plasma confined in a Penning-Malmberg trap is investigated by means of a two-dimensional particle-in-cell numerical code. The transverse plasma dynamics is studied both in the case of free evolution and under the influence of non-axisymmetric, multipolar radio-frequency drives applied on the circular conducting boundary. In the latter case the radio-frequency fields are chosen in the frequency range of the low-order azimuthal (diocotron) modes of the plasma in order to investigate their effect on the insurgence of azimuthal instabilities and the formation and evolution of coherent structures, possibly preventing the relaxation to a fully-developed turbulent state. Different initial density distributions (rings and spirals) are considered, so that evolutions characterized by different levels of turbulence and intermittency are obtained. The time evolution of integral and spectral quantities of interest are computed using a multiresolution analysis based on a wavelet decomposition of density maps. Qualitative features of turbulent relaxation are found to be similar in conditions of both free and forced evolution, but the analysis allows one to highlight fine details of the flow beyond the self-similarity turbulence properties, so that the influence of the initial conditions and the effect of the external forcing can be distinguished. In particular, the presence of small inhomogeneities in the initial density configuration turns out to lead to quite different final states, especially in the presence of competing unstable diocotron modes characterized by similar growth rates.

  9. Prospects for the creation of positron-electron plasmas in a non-neutral stellarator

    International Nuclear Information System (INIS)

    Pedersen, T Sunn; Boozer, A H; Dorland, W; Kremer, J P; Schmitt, R

    2003-01-01

    The prospects of creating positron-electron plasmas confined in a stellarator are discussed. A pure electron plasma would be created before the positrons are introduced, to facilitate efficient injection and a long confinement time of the positrons. Gyrokinetic simulations are presented suggesting that a positron-electron plasma may be stable to low-frequency microturbulence if operated well below the Brillouin limit, and transport may be neoclassical. If this is the case, significant positron-electron plasma densities can be reached with positron sources that exist today

  10. The King model for electrons in a finite-size ultracold plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vrinceanu, D; Collins, L A [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Balaraman, G S [School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2008-10-24

    A self-consistent model for a finite-size non-neutral ultracold plasma is obtained by extending a conventional model of globular star clusters. This model describes the dynamics of electrons at quasi-equilibrium trapped within the potential created by a cloud of stationary ions. A random sample of electron positions and velocities can be generated with the statistical properties defined by this model.

  11. Introduction to plasma physics and controlled fusion

    CERN Document Server

    Chen, Francis F

    2016-01-01

    The third edition of this classic text presents a complete introduction to plasma physics and controlled fusion, written by one of the pioneering scientists in this expanding field.  It offers both a simple and intuitive discussion of the basic concepts of the subject matter and an insight into the challenging problems of current research. This outstanding text offers students a painless introduction to this important field; for teachers, a large collection of problems; and for researchers, a concise review of the fundamentals as well as original treatments of a number of topics never before explained so clearly.  In a wholly lucid manner the second edition covered charged-particle motions, plasmas as fluids, kinetic theory, and nonlinear effects.  For the third edition, two new chapters have been added to incorporate discussion of more recent advances in the field.  The new chapter 9 on Special Plasmas covers non-neutral plasmas, pure electron plasmas, solid and ultra-cold plasmas, pair-ion plasmas, d...

  12. Density gradient instabilities in a neutron inhomogeneous guiding-centre plasma

    International Nuclear Information System (INIS)

    Shoucri, M.M.; Gagne, R.R.J.

    1977-01-01

    The guiding-centre equations for a plasma of cold ions and thermal electrons admit neutral and non-neutral inhomogeneous equilibrium solutions, and the linear stability of these solutions has been recently investigated numerically by Shoucri and Knorr (1975). With arbitrary density profiles, numerical techniques appear to be the only practical way to study the linear stability of the inhomogeneous equilibrium solutions for the guiding centre plasma. However, analytical methods can be applied to some simple types of density profiles. The purpose of the present note is to present some analytical results on the linear instabilities of an inhomogeneous neutral guiding centre plasma. (U.K.)

  13. Flute instability growth on a magnetized plasma column

    International Nuclear Information System (INIS)

    Rose, D. V.; Genoni, T. C.; Welch, D. R.; Mehlhorn, T. A.; Porter, J. L.; Ditmire, T.

    2006-01-01

    The growth of the flute-type instability for a field-aligned plasma column immersed in a uniform magnetic field is studied. Particle-in-cell simulations are compared with a semi-analytic dispersion analysis of the drift cyclotron instability in cylindrical geometry with a Gaussian density profile in the radial direction. For the parameters considered here, the dispersion analysis gives a local maximum for the peak growth rates as a function of R/r i , where R is the Gaussian characteristic radius and r i is the ion gyroradius. The electrostatic and electromagnetic particle-in-cell simulation results give azimuthal and radial mode numbers that are in reasonable agreement with the dispersion analysis. The electrostatic simulations give linear growth rates that are in good agreement with the dispersion analysis results, while the electromagnetic simulations yield growth rate trends that are similar to the dispersion analysis but that are not in quantitative agreement. These differences are ascribed to higher initial field fluctuation levels in the electromagnetic field solver. Overall, the simulations allow the examination of both the linear and nonlinear evolution of the instability in this physical system up to and beyond the point of wave energy saturation

  14. Modes in a non-neutral plasma of finite length, m=0,1

    International Nuclear Information System (INIS)

    Rasband, S. Neil; Spencer, Ross L.

    2003-01-01

    For realistic, cold equilibria of finite length representing a pure electron plasma confined in a cylindrical Malmberg-Penning trap, the mode spectrum for Trivelpiece-Gould, m=0, and for diocotron, m=1, modes is calculated numerically. A novel method involving finite elements is used to successfully compute eigenfrequencies and eigenfunctions for plasma equilibria shaped like pancakes, cigars, long cylinders, and all things in between. Mostly sharp-boundary density configurations are considered but also included in this study are diffuse density profiles including ones with peaks off axis leading to instabilities. In all cases the focus has been on elucidating the role of finite length in determining mode frequencies and shapes. For m=0 accurate eigenfrequencies are tabulated and their dependence on mode number and aspect ratio is computed. For m=1 it is found that the eigenfrequencies are 2% to 3% higher than given by the Fine-Driscoll formula [Phys. Plasmas 5, 601 (1998)]. The 'new modes' of Hilsabeck and O'Neil [Phys. Plasmas 8, 407 (2001)] are identified as Dubin modes. For hollow profiles finite length in cold-fluid can account for up to ∼70% of the theoretical instability growth rate

  15. Plasma state. The universe's fire

    International Nuclear Information System (INIS)

    Lehner, Th.

    2004-01-01

    The plasma is the fourth state of matter, obtained at a very high temperature by the separation of the electrons from their nuclei. Plasma represents 99% of the visible mass of our present day universe and was the unique state of matter at its very beginning. Plasmas are present in the core of stars and in the interstellar environment. More closer to us, they are responsible of spectacular phenomena, like aurora borealis, lightning, comet queues etc.. This book makes a review of the different types of plasmas (electromagnetic, Earth's plasmas, spatial plasmas, solar plasmas, astrophysical plasmas). One chapter presents the thermonuclear fusion as future energy source. Another one treats of the chaos and turbulence inside plasmas. Some applications of plasmas are reviewed: MHD and ionic propulsion systems, MHD energy conversion and MHD generators, thermo-ionic converters, solid-state plasmas, particle accelerators, coherent radiation sources, 'Zeta' machines, X-ray lasers, isotopic separation, non-neutral plasmas and charged beams, free-electrons lasers, electrons and positrons plasmas, industrial applications (etching and cleaning, manufacturing of solar cells, flat screens, industrial reactors, waste treatment, cold plasma-assisted sterilization, effluents decontamination etc.). A last chapter makes an overview of the modern research in plasma physics. (J.S.)

  16. Estimate of electrical potential difference between plasmas with different degrees of ionization

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-12

    The electrical potential difference has been estimated across the mixing region of two plasmas with different degrees of ionization. The estimation has been carried out in two different contexts of a charge neutral mixing region and a charge non-neutral sheath. Ion energy gained due to the potential difference has also been estimated. In both analyses, ion energy gain is proportional to the degree of ionization, and a fairly large ionization appears to be needed for overcoming the potential energy barrier of strongly coupled plasmas.

  17. Compact electron beam focusing column

    Science.gov (United States)

    Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

    2001-12-01

    A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

  18. Positive-column plasma studied by fast-flow glow discharge mass spectrometry: Could it be a 'Rydberg gas?'

    International Nuclear Information System (INIS)

    Mason, Rod S.; Miller, Pat D.; Mortimer, Ifor; Mitchell, David J.; Dash, Neil A.

    2003-01-01

    Ions created from the fast-flowing positive column plasma of a glow discharge were monitored using a high voltage magnetic sector mass spectrometer. Since the field gradient and sheath potentials created by the plasma inside the source opposed cation transfer, it is inferred that the ions detected were the field-ionized Rydberg species. This is supported by the mass spectral changes which occurred when a negative bias was applied to the sampling aperture and by the contrasting behavior when attached to a quadrupole analyzer. Reaction with H 2 (titrated into the flowing plasma) quenched not only the ionization of discharge gas Rydberg atoms but also the passage of electric current through the plasma, without significant changes to the field and sheath potentials. Few 'free' ions were present and the lifetimes of the Rydberg atoms detected were much longer than seen in lower pressure experiments, indicating additional stabilization in the plasma environment. The observations support the model of the flowing plasma, given previously [R. S. Mason, P. D. Miller, and I. P. Mortimer, Phys. Rev. E 55, 7462 (1997)] as mainly a neutral Rydberg atom gas, rather than a conventional ion-electron plasma

  19. [Online enrichment ability of restricted-access column coupled with high performance liquid chromatography by column switching technique for benazepril hydrochloride].

    Science.gov (United States)

    Zhang, Xiaohui; Wang, Rong; Xie, Hua; Yin, Qiang; Li, Xiaoyun; Jia, Zhengping; Wu, Xiaoyu; Zhang, Juanhong; Li, Wenbin

    2013-05-01

    The online enrichment ability of the restricted-access media (RAM) column coupled with high performance liquid chromatography by column switching technique for benazepril hydrochloride in plasma was studied. The RAM-HPLC system consisted of an RAM column as enrichment column and a C18 column as analytical column coupled via the column switching technique. The effects of the injection volume on the peak area and the systematic pressure were studied. When the injection volume was less than 100 microL, the peak area increased with the increase of the injection volume. However, when the injection volume was more than 80 microL, the pressure of whole system increased obviously. In order to protect the whole system, 80 microL was chosen as the maximum injection volume. The peak areas of ordinary injection and the large volume injection showed a good linear relationship. The enrichment ability of RAM-HPLC system was satisfactory. The system was successfully used for the separation and detection of the trace benazepril hydrochloride in rat plasma after its administration. The sensitivity of HPLC can be improved by RAM pre-enrichment. It is a simple and economic measurement method.

  20. Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters.

    Science.gov (United States)

    Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

    2016-01-21

    This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

  1. Computer simulation of the formation of Langmuir solitons and holes in a cylindrical magnetized plasma column

    International Nuclear Information System (INIS)

    Turikov, V.A.

    1978-06-01

    Nonlinear plasma oscillations in a cylindrical plasma resulting from a short localized external excitation are examined by means of a particle-in-cell simulation scheme. Computer calculations are performed for describing the experimental results obtained in a single-ended Q-machine plasma in a cylindrical waveguide. It is assumed that there is a strong magnetic field in the direction of the column axis. When the amplitude of the excitation potential is close to the kinetic energy of electrons having a phase velocity of the electron plasma wave, the formation is observed of solitons and holes in phase space. After formation, the solitons and holes move with constant velocities. The velocities of solitons are close to the wave-phase velocity, while holes move with smaller velocities. When the external potential amplitude is increased, there is a tendency that the number of holes grows. The potential amplitude of the self-consistent field in the soliton region damps in time with increasing soliton width. The potential profile of the hole does not change after its formation. (Auth.)

  2. Improved tumor imaging with radiolabeled monoclonal antibodies by plasma clearance with anti-antibody column

    International Nuclear Information System (INIS)

    Lear, J.L.; Kasliwal, R.; Feyerabend, A.; Bunn, P.; Dienhart, D.G.; Johnson, T.K.; Glenn, S.D.; Maddock, S.W.

    1990-01-01

    This paper reports on imaging of tumors with use of radiolabeled monoclonal antibodies (MoAs) that often hindered by high levels of background activity. The ability to lower blood pool MoA activity at a selected time after injection offers a potential method to reduce background while preserving tumor uptake. Toward this goal, the authors investigated the process of clearing MoA from patients' plasma with use of an anti-antibody column. One patient with breast cancer and four with lung cancer were given intravenous injection of 5 mCi of indium-111 KC4 (Coulter Immunology) and imaged at 20, 24, 48, and 72 hours with use of a whole-body canner coupled to a computer. Plasma clearance was performed between the 20- and 24-hour images with use of a COBEIA system. Images were inspected visually and analyzed by region-of-interest quantification

  3. Aspartic acid incorporated monolithic columns for affinity glycoprotein purification.

    Science.gov (United States)

    Armutcu, Canan; Bereli, Nilay; Bayram, Engin; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

    2014-02-01

    Novel aspartic acid incorporated monolithic columns were prepared to efficiently affinity purify immunoglobulin G (IgG) from human plasma. The monolithic columns were synthesised in a stainless steel HPLC column (20 cm × 5 mm id) by in situ bulk polymerisation of N-methacryloyl-L-aspartic acid (MAAsp), a polymerisable derivative of L-aspartic acid, and 2-hydroxyethyl methacrylate (HEMA). Monolithic columns [poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid) (PHEMAsp)] were characterised by swelling studies, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The monolithic columns were used for IgG adsorption/desorption from aqueous solutions and human plasma. The IgG adsorption depended on the buffer type, and the maximum IgG adsorption from aqueous solution in phosphate buffer was 0.085 mg/g at pH 6.0. The monolithic columns allowed for one-step IgG purification with a negligible capacity decrease after ten adsorption-desorption cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Industrial Structure, Menu Costs and the Non-Neutrality of Money

    DEFF Research Database (Denmark)

    Dixon, Huw David; Hansen, Claus Thustrup

    by perfect competition. The mixed industrial structure implies that there is a misallocation of the input (labour) between sectors. Following a 5% monetary expansion, the menu costs required for price rigidity in the monopolistic sector can be 50 times smaller than in the symmetric case, while the ratio......New Keynesian literature assumes symmetric industrial structure when analysing explanations of monetary non-neutrality. We analyse the impact of modifying this assumption by allowing for a mixed industrial structure; some industries are characterized by monopolistic competition, and others...... of welfare gain to private loss can be as large as 200 times the corresponding symmetric case. This implies that in real world economies, menu costs may be even more significant than previously thought...

  5. Magnetic spires for the detection of the position of the plasma column in a Tokamak (linear approximation); Espiras magneticas para la deteccion de la posicion de la columna de plasma en un Tokamak (aproximacion lineal)

    Energy Technology Data Exchange (ETDEWEB)

    Colunga S, S

    1990-07-15

    In this report the simplified analysis of a method to detect the movement of the plasma column of a tokamak in the vertical direction and of the biggest radius is given. The peculiar case of the Tokamak Novillo of the Plasma Physics Laboratory of the ININ is studied. (Author)

  6. Fundamental Processes in Plasmas. Final report

    International Nuclear Information System (INIS)

    O'Neil, Thomas M.; Driscoll, C. Fred

    2009-01-01

    This research focuses on fundamental processes in plasmas, and emphasizes problems for which precise experimental tests of theory can be obtained. Experiments are performed on non-neutral plasmas, utilizing three electron traps and one ion trap with a broad range of operating regimes and diagnostics. Theory is focused on fundamental plasma and fluid processes underlying collisional transport and fluid turbulence, using both analytic techniques and medium-scale numerical simulations. The simplicity of these systems allows a depth of understanding and a precision of comparison between theory and experiment which is rarely possible for neutral plasmas in complex geometry. The recent work has focused on three areas in basic plasma physics. First, experiments and theory have probed fundamental characteristics of plasma waves: from the low-amplitude thermal regime, to inviscid damping and fluid echoes, to cold fluid waves in cryogenic ion plasmas. Second, the wide-ranging effects of dissipative separatrices have been studied experimentally and theoretically, finding novel wave damping and coupling effects and important plasma transport effects. Finally, correlated systems have been investigated experimentally and theoretically: UCSD experients have now measured the Salpeter correlation enhancement, and theory work has characterized the 'guiding center atoms of antihydrogen created at CERN

  7. Neutral and Non-Neutral Evolution of Duplicated Genes with Gene Conversion

    Directory of Open Access Journals (Sweden)

    Jeffrey A. Fawcett

    2011-02-01

    Full Text Available Gene conversion is one of the major mutational mechanisms involved in the DNA sequence evolution of duplicated genes. It contributes to create unique patters of DNA polymorphism within species and divergence between species. A typical pattern is so-called concerted evolution, in which the divergence between duplicates is maintained low for a long time because of frequent exchanges of DNA fragments. In addition, gene conversion affects the DNA evolution of duplicates in various ways especially when selection operates. Here, we review theoretical models to understand the evolution of duplicates in both neutral and non-neutral cases. We also explain how these theories contribute to interpreting real polymorphism and divergence data by using some intriguing examples.

  8. A canonical perturbation method for computing the guiding-center motion in magnetized axisymmetric plasma columns

    International Nuclear Information System (INIS)

    Gratreau, P.

    1987-01-01

    The motion of charged particles in a magnetized plasma column, such as that of a magnetic mirror trap or a tokamak, is determined in the framework of the canonical perturbation theory through a method of variation of constants which preserves the energy conservation and the symmetry invariance. The choice of a frame of coordinates close to that of the magnetic coordinates allows a relatively precise determination of the guiding-center motion with a low-ordered approximation in the adiabatic parameter. A Hamiltonian formulation of the motion equations is obtained

  9. Experimental Confirmation of Stable, Small-Debye-Length, Pure-Electron-Plasma Equilibria in a Stellarator

    International Nuclear Information System (INIS)

    Kremer, J. P.; Pedersen, T. Sunn; Lefrancois, R. G.; Marksteiner, Q.

    2006-01-01

    The creation of the first small-Debye length, low temperature pure electron plasmas in a stellarator is reported. A confinement time of 20 ms has been measured. The long confinement time implies the existence of macroscopically stable equilibria and that the single particle orbits are well confined despite the lack of quasisymmetry in the device, the Columbia non-neutral torus. This confirms the beneficial confinement effects of strong electric fields and the resulting rapid ExB rotation of the electrons. The particle confinement time is presently limited by the presence of bulk insulating materials in the plasma, rather than any intrinsic plasma transport processes. A nearly flat temperature profile is seen in the inner part of the plasma

  10. Experimental confirmation of stable, small-debye-length, pure-electron-plasma equilibria in a stellarator.

    Science.gov (United States)

    Kremer, J P; Pedersen, T Sunn; Lefrancois, R G; Marksteiner, Q

    2006-09-01

    The creation of the first small-Debye length, low temperature pure electron plasmas in a stellarator is reported. A confinement time of 20 ms has been measured. The long confinement time implies the existence of macroscopically stable equilibria and that the single particle orbits are well confined despite the lack of quasisymmetry in the device, the Columbia non-neutral torus. This confirms the beneficial confinement effects of strong electric fields and the resulting rapid E x B rotation of the electrons. The particle confinement time is presently limited by the presence of bulk insulating materials in the plasma, rather than any intrinsic plasma transport processes. A nearly flat temperature profile is seen in the inner part of the plasma.

  11. Space-time evolution of the power absorbed by creating and heating a hydrogen plasma column by a pulsed laser beam

    International Nuclear Information System (INIS)

    Pincosy, Philip; Dufresne, Daniel; Bournot, Philippe; Caressa, J.-P.; Autric, Michel

    1976-01-01

    Space-time measurements of light intensity are presented for the analysis of the processes involved in the creation and heating of an under-dense hydrogen plasma column by a pulsed CO 2 laser beam. The laser beam trapping due to the rapid development of a radial electron density gradient is specifically demonstrated. Time measurements of the changes in the laser power longitudinally transmitted through the plasma give evidence for a significant absorption of the incident power during the first 150 nanoseconds of the interaction [fr

  12. Excitation of THz hybrid modes in an elliptical dielectric rod waveguide with a cold collisionless unmagnetized plasma column by an annular electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Rahmani, Z., E-mail: z.rahmani@kashanu.ac.ir; Safari, S. [Department of Laser and Photonics, Faculty of Physics, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Heidari-Semiromi, E. [Department of Condense Matter, Faculty of Physics, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of)

    2016-06-15

    The dispersion relation of electromagnetic waves propagating in an elliptical plasma waveguide with a cold collisionless unmagnetized plasma column and a dielectric rod is studied analytically. The frequency spectrum of the hybrid waves and the growth rate for excitation of the waves by a thin annular relativistic elliptical electron beam (TAREEB) is obtained. The effects of relative permittivity constant of dielectric rod, geometrical dimensions, plasma frequency, accelerating voltage, and current density of TAREEB on the growth rate and frequency spectra of the waveguide will be investigated.

  13. Plasma diagnostic development and UHV testing for the ALPHA collaboration at Marquette University

    Science.gov (United States)

    Tharp, T. D.; Alpha Collaboration

    2017-10-01

    At Marquette, we are developing the next generation of nonneutral plasma diagnostics for the ALPHA experiment at CERN. ALPHA is building a new vertical experiment to test the gravitational interaction of antihydrogen with Earth. This expansion requires significant changes to the design of our plasma diagnostic suites: the next generation of tools must be able to measure plasmas from two directions, and must be capable of operating in a horizontal position. The diagnostic suite includes measurements of plasma density, shape, and temperature. The hardware used includes a MicroChannel Plate (MCP), a Faraday Cup, and an electron gun. In addition, we are building a vacuum chamber to test the viability of 3-d printed components for UHV compatibility, with target pressures of 10-10 mbar.

  14. En route to matter-antimatter pair plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stenson, Eve V.; Hergenhahn, Uwe; Paschkowski, Norbert; Saitoh, Haruhiko; Stanja, Juliane [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Niemann, Holger; Sunn Pedersen, Thomas [Max Planck Institute for Plasma Physics, Greifswald and Garching (Germany); Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Schweikhard, Lutz [Ernst Moritz Arndt University of Greifswald, Greifswald (Germany); Hugenschmidt, Christoph [Technische Universitaet Muenchen, Garching (Germany); Danielson, James R.; Surko, Clifford M. [University of California, San Diego, La Jolla (United States)

    2015-05-01

    The APEX and PAX projects have as their overarching goal the laboratory creation and confinement of the world's first positron-electron pair plasma. Plasmas of this type have been the subject of hundreds of theoretical investigations and are also believed to play a role in various astrophysical environments. In order to achieve this goal in an experimentally accessible volume (e.g., 10 liters), a record number (≥ 10{sup 10}) of cold (∝ 1 eV) positrons are to be accumulated and combined with a corresponding population of electrons. Notable requirements include a high-intensity positron beam (such as NEPOMUC), a suitable magnetic confinement device for the pair plasma (such as a levitated dipole), high-efficiency tools for bridging the two (i.e., means by which the positrons can be efficiently cooled, trapped, and injected across flux surfaces), and diagnostics not only for the pair plasma, but also for the positron beam and for intermediary non-neutral plasmas. This talk will summarize the project as a whole and recent work by the APEX/PAX team on its various elements.

  15. Electron waves and resonances in bounded plasmas

    CERN Document Server

    Vandenplas, Paul E

    1968-01-01

    General theoretical methods and experimental techniques ; the uniform plasma slab-condenser system ; the hollow cylindrical plasma ; scattering of a plane electromagnetic wave by a plasma column in steady magnetic fields (cold plasma approximation) ; hot non-uniform plasma column ; metallic and dielectric resonance probes, plasma-dielectric coated antenna, general considerations.

  16. Confinement time exceeding one second for a toroidal electron plasma.

    Science.gov (United States)

    Marler, J P; Stoneking, M R

    2008-04-18

    Nearly steady-state electron plasmas are trapped in a toroidal magnetic field for the first time. We report the first results from a new toroidal electron plasma experiment, the Lawrence Non-neutral Torus II, in which electron densities on the order of 10(7) cm(-3) are trapped in a 270-degree toroidal arc (670 G toroidal magnetic field) by application of trapping potentials to segments of a conducting shell. The total charge inferred from measurements of the frequency of the m=1 diocotron mode is observed to decay on a 3 s time scale, a time scale that approaches the predicted limit due to magnetic pumping transport. Three seconds represents approximately equal to 10(5) periods of the lowest frequency plasma mode, indicating that nearly steady-state conditions are achieved.

  17. Radiation pattern of open ended waveguide in air core surrounded by annular plasma column

    International Nuclear Information System (INIS)

    Sharma, D.R.; Verma, J.S.

    1977-01-01

    Radiation pattern of open ended waveguide excited in circular symmetric mode (TM 01 ) in an air core having central conductor and surrounded by an annular plasma column is studied. The field distribution at the open end of the waveguide is considered to be equivalent to the vector sum of magnetic current rings of various radii, ranging from the outer radius of the inner conductor to the inner radius of the outer conductor of the waveguide at the open end. The radiation field is obtained as a vector sum of field components due to individual rings of current. Such a configuration gives rise to multiple narrow radiation beams away from the critical angle. (author)

  18. Influence of a transverse magnetic field on arc root movements in a dc plasma torch: Diamagnetic effect of arc column

    International Nuclear Information System (INIS)

    Kim, Keun Su

    2009-01-01

    The effect of a transverse magnetic field on the anodic arc root movement inside a dc plasma torch has been investigated. The arc voltage fluctuation, which represents the degree of the arc instability, was reduced to 28.6% of the original value and the high frequency components in the voltage signal also decreased in their magnitudes. The inherent arc instability in a dc thermal plasma torch seems to be suppressed by a diamagnetic effect of the arc column. Furthermore, the measured voltage wave forms indicated that the arc root attachment mode would be controllable by a transverse magnetic field

  19. High-throughput liquid chromatography for drug analysis in biological fluids: investigation of extraction column life.

    Science.gov (United States)

    Zeng, Wei; Fisher, Alison L; Musson, Donald G; Wang, Amy Qiu

    2004-07-05

    A novel method was developed and assessed to extend the lifetime of extraction columns of high-throughput liquid chromatography (HTLC) for bioanalysis of human plasma samples. In this method, a 15% acetic acid solution and 90% THF were respectively used as mobile phases to clean up the proteins in human plasma samples and residual lipids from the extraction and analytical columns. The 15% acetic acid solution weakens the interactions between proteins and the stationary phase of the extraction column and increases the protein solubility in the mobile phase. The 90% THF mobile phase prevents the accumulation of lipids and thus reduces the potential damage on the columns. Using this novel method, the extraction column lifetime has been extended to about 2000 direct plasma injections, and this is the first time that high concentration acetic acid and THF are used in HTLC for on-line cleanup and extraction column lifetime extension.

  20. Simultaneous determination of F-beta-alanine and beta-alanine in plasma and urine with dual-column reversed-phase high-performance liquid chromatography

    NARCIS (Netherlands)

    van Kuilenburg, A. B.; Stroomer, A. E.; Peters, G. J.; van Gennip, A. H.

    2001-01-01

    F-beta-Alanine and beta-alanine were detected in plasma and urine samples with fluorescence detection of orthophthaldialdehyde derivatives of F-beta-alanine and beta-alanine after separation with dual-column reversed-phase HPLC. The detection limits of F-beta-alanine and beta-alanine in the HPLC

  1. Micro-column plasma emission liquid chromatograph. [Patent application

    Science.gov (United States)

    Gay, D.D.

    1982-08-12

    In a direct current plasma emission spectrometer for use in combination with a microcolumn liquid chromatograph, an improved plasma source unit is claimed. The plasma source unit includes a quartz capillary tube having an inlet means, outlet off gas means and a pair of spaced electrodes defining a plasma region in the tube. The inlet means is connected to and adapted to receive eluant of the liquid chromatograph along with a stream of plasma-forming gas. There is an opening through the wall of the capillary tube penetrating into the plasma region. A soft glass capillary light pipe is disposed at the opening, is connected to the spectrometer, and is adapted to transmit light passing from the plasma region to the spectrometer. There is also a source of electromotive force connected to the electrodes sufficient to initiate and sustain a plasma in the plasma region of the tube.

  2. Investigation of the helicon discharge plasma parameters in a hybrid RF plasma system

    International Nuclear Information System (INIS)

    Aleksandrov, A. F.; Petrov, A. K.; Vavilin, K. V.; Kralkina, E. A.; Neklyudova, P. A.; Nikonov, A. M.; Pavlov, V. B.; Ayrapetov, A. A.; Odinokov, V. V.; Sologub, V. A.; Pavlov, G. Ya.

    2016-01-01

    Results of an experimental study of the helicon discharge plasma parameters in a prototype of a hybrid RF plasma system equipped with a solenoidal antenna are described. It is shown that an increase in the external magnetic field leads to the formation of a plasma column and a shift of the maximum ion current along the discharge axis toward the bottom flange of the system. The shape of the plasma column can be controlled via varying the configuration of the magnetic field.

  3. Investigation of the helicon discharge plasma parameters in a hybrid RF plasma system

    Energy Technology Data Exchange (ETDEWEB)

    Aleksandrov, A. F.; Petrov, A. K., E-mail: alpetrov57@gmail.com; Vavilin, K. V.; Kralkina, E. A.; Neklyudova, P. A.; Nikonov, A. M.; Pavlov, V. B. [Moscow State University, Faculty of Physics (Russian Federation); Ayrapetov, A. A.; Odinokov, V. V.; Sologub, V. A.; Pavlov, G. Ya. [Research Institute of Precision Engineering (Russian Federation)

    2016-03-15

    Results of an experimental study of the helicon discharge plasma parameters in a prototype of a hybrid RF plasma system equipped with a solenoidal antenna are described. It is shown that an increase in the external magnetic field leads to the formation of a plasma column and a shift of the maximum ion current along the discharge axis toward the bottom flange of the system. The shape of the plasma column can be controlled via varying the configuration of the magnetic field.

  4. Chiral high-performance liquid chromatographic analysis of fluoxetine and norfluoxetine in rabbit plasma, urine, and vitreous humor using an acetylated beta-cyclodextrin column.

    Science.gov (United States)

    Yee, L; Wong, S H; Skrinska, V A

    2000-10-01

    Fluoxetine (Prozac) is a potent selective serotonin reuptake inhibitor used for the treatment of major depression. Both fluoxetine (F) and its demethylated metabolite, norfluoxetine (NF), are racemic. S-Fluoxetine (SF) and S-norfluoxetine (SNF) are more potent inhibitors of serotonin reuptake than R-fluoxetine (RF) and R-norfluoxetine (RNF). Quantitation of individual enantiomers may provide a greater understanding of pharmacokinetic properties. The objective of this study was to perform a limited chiral selectivity study using rabbit plasma, urine, and vitreous humor analyzed by a solid-phase extraction protocol and a newly developed chiral analysis with an acetylated beta-cyclodextrin (CD) column. Liquid chromatographic parameters for CD were as follows: a mobile phase composition of methanol/0.3% triethylamine buffer, pH 5.6, (30:70), a flow rate of 1 mL/min, detection at 214 nm, and a temperature of 40 degrees C. Elution order was SNF, SF, RNF, and RF with capacity factors of 6, 7, 8, and 9, respectively. The corresponding resolution factors were as follows: R1,2 = 0.8, R2,3 = 1.2, and R3,4 = 0.9. The conditions for solid-phase extraction were optimized for Varian Bond Elut Certify columns. Following sample application, the column was rinsed with water, acetic acid, and then with methanol. Drug enantiomers were eluted with methylene chloride, isopropanol, and ammonium hydroxide (78:20:2). After extract evaporation, the extract residue was reconstituted for high-performance liquid chromatographic analysis. To investigate chiral pharmacology, a biodistribution study was performed by administering 2 mg/kg of F to five rabbits. Blood, urine, and vitreous specimens were collected. Plasma samples collected 45 min postinjection showed nearly equal concentrations of RF and SE After 24 h, the only metabolite detected in plasma was RNF. Drugs were not detectable in vitreous humor. Urine concentrations of SNF, SF, RNF, and RF were 51, 76, 34, and 8 microg/L, respectively

  5. Cooperativity between CD8+ T cells, non-neutralizing antibodies, and alveolar macrophages is important for heterosubtypic influenza virus immunity.

    Directory of Open Access Journals (Sweden)

    Brian J Laidlaw

    2013-03-01

    Full Text Available Seasonal epidemics of influenza virus result in ∼36,000 deaths annually in the United States. Current vaccines against influenza virus elicit an antibody response specific for the envelope glycoproteins. However, high mutation rates result in the emergence of new viral serotypes, which elude neutralization by preexisting antibodies. T lymphocytes have been reported to be capable of mediating heterosubtypic protection through recognition of internal, more conserved, influenza virus proteins. Here, we demonstrate using a recombinant influenza virus expressing the LCMV GP33-41 epitope that influenza virus-specific CD8+ T cells and virus-specific non-neutralizing antibodies each are relatively ineffective at conferring heterosubtypic protective immunity alone. However, when combined virus-specific CD8 T cells and non-neutralizing antibodies cooperatively elicit robust protective immunity. This synergistic improvement in protective immunity is dependent, at least in part, on alveolar macrophages and/or other lung phagocytes. Overall, our studies suggest that an influenza vaccine capable of eliciting both CD8+ T cells and antibodies specific for highly conserved influenza proteins may be able to provide heterosubtypic protection in humans, and act as the basis for a potential "universal" vaccine.

  6. Dynamic shear stabilization of hydromagnetic instabilities in low-beta plasma column by a frequency near the ion cyclotron frequency

    International Nuclear Information System (INIS)

    Minami, Kazuo; Sato, Kazunori.

    1978-09-01

    The dynamic shear stabilization of the hydromagnetic instability in low-beta plasmas by an axial RF current whose frequency is not much smaller than the ion cyclotron frequency ωsub(ci) is analyzed in some detail. We adopt the simple model of a uniform plasma column with infinite conductivity. Attention is limited to the case of the m = 1 kink mode with long wave lengths. The Mathieu equation, in which the effect of the ion cyclotron motion is taken into account, is derived. It is shown that the dynamic shear stabilization is still effective, even if the frequency of the applied RF current is of the order of ωsub(ci), which is considerably higher than the frequencies believed to be available in the previous analyses. (author)

  7. [Simultaneous determination of tryptophan and its metabolites in plasma by high performance liquid chromatography with on-column derivatization].

    Science.gov (United States)

    Feng, Chengya; Gao, Jieying; Zhen, Qianna; Fan, Zimian; Zhu, Mingsong; Yang, Xiangchun; Ding, Min

    2013-06-01

    A high performance liquid chromatography-ultraviolet/fluorescence detection (HPLC-UV/FLD) with on-column derivatization was established to simultaneously determine tryptophan (Trp), kynurenine (Kyn), 5-hydroxyindole acetic acid (5-Hiaa) and kynurenic acid (Kyna). A Hypersil C-18 column (250 mm x 4.0 mm, 5 microm) was used for the analysis at 30 degrees C. The separation was carried out with the mobile phase consisting of 250 mmol/L zinc acetate (pH 5.5) and acetonitrile (95: 5, v/v) at a flow rate of 0.8 mL/min using 3-nitrotyrosine as internal standard (IS). The excitation (Ex) and emission (Em) wavelengths were set at 278 nm (lambda(ex))/343 nm (lambda(em)) for 5-Hiaa and 244 nm (lambda(ex))/400 nm (lambda(em)) for Kyna, while the wavelengths of ultraviolet detection were set at 360 nm for Kyn and IS, 302 nm for Trp. The recoveries were in the range of 91.62% to 114.17%. The linearities were from 2.50 micromol/L to 320.00 micromol/L for Trp, 0.32 micromol/L to 15.36 micromol/L for Kyn, 3.27 nmol/L to 104.60 nmol/L for 5-Hiaa, and 14.00 nmol/L to 464.80 nmol/L for Kyna. The detection limits were 0.078 micromol/L, 0.056 micromol/L, 0.690 nmol/L and 1.290 nmol/L for Trp, Kyn, 5-Hiaa, and Kyna, respectively. Thirty plasma samples of normal pregnant women and 28 plasma samples of healthy controls were tested, and the results exhibited that the concentrations of Trp, Kyn and Kyna in the plasma of the normal pregnant women were significantly different from those of the control group (all P < 0.01). The method is simple and sensitive with good reproducibility, and it is suitable for clinical measurements.

  8. Vacuum-arc plasma centrifuge applied to stable isotope separation

    International Nuclear Information System (INIS)

    Del Bosco, E.

    1989-09-01

    This work describes the results of a vacuum-arc plasma centrifuge experiment. A plasma centrifuge is an apparatus where a plasma column is produced due to the interaction of an electric current with an externally applied magnetic field, sup(→)J x sup(→)B. Among the applications of a rotating plasma, this work deals particularly with its utilization in an isotope enrichment device. The main characteristics of the plasma produced in this experiment are presented, with special attention to the plasma column rotation and the isotope enrichment. The analysis of the results is performed using a fluid model for a completely ionized rigid body rotating plasma column in steady state equilibrium. The main results are: a) rotation frequency of the plasma column in the range 2 x 10 sup(4) to 3 x 10 sup(5) rad/s; b) enrichment of 10 to 30% for the magnesium isotopes, and of 290 to 490% for the carbon 13 isotope; c) rigid body rotation of the plasma column only for radii smaller than the characteristic radius of the plasma column. re; d) linear dependence of the rotation frequency upon the magnetic field strength only for r < re; e) existence of an optimum value of the magnetic field for maximum enrichment; and f) dependence of the rotation frequency upon the inverse of the atomic mass. (author)

  9. Direct-injection HPLC method of measuring micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column.

    Science.gov (United States)

    Uranishi, Hiroaki; Nakamura, Mitsuhiro; Nakamura, Hiroki; Ikeda, Yukari; Otsuka, Mayuko; Kato, Zenichiro; Tsuchiya, Teruo

    2011-04-15

    A direct-injection HPLC-based method has been developed for determining amounts of micafungin in human plasma using a novel hydrophobic/hydrophilic hybrid ODS column. The method is easy to perform and requires only 10 μL of a filtered plasma sample. The chromatographic separations were carried out with a gradient mode. The fluorescence detection wavelengths of excitation and emission were set at 273 nm and 464 nm, respectively. Retention times for micafungin and IS were 22.4 and 23.7 min, respectively. Micafungin and FR195743 (IS) peaks were completely separated with little tailing, and no interference was observed. The calibration curve of micafungin showed good linearity in the range of 0.5-20.0 μg/mL (r(2)=1.00). The intra-day accuracy ranged from -4.5 to 5.3%. The inter-day accuracy ranged from -9.8 to 1.5%. The precisions were less than 10%. This method is useful for the determination of micafungin in human plasma. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Parametric analysis of a magnetized cylindrical plasma

    International Nuclear Information System (INIS)

    Ahedo, Eduardo

    2009-01-01

    The relevant macroscopic model, the spatial structure, and the parametric regimes of a low-pressure plasma confined by a cylinder and an axial magnetic field is discussed for the small-Debye length limit, making use of asymptotic techniques. The plasma response is fully characterized by three-dimensionless parameters, related to the electron gyroradius, and the electron and ion collision mean-free-paths. There are the unmagnetized regime, the main magnetized regime, and, for a low electron-collisionality plasma, an intermediate-magnetization regime. In the magnetized regimes, electron azimuthal inertia is shown to be a dominant phenomenon in part of the quasineutral plasma region and to set up before ion radial inertia. In the main magnetized regime, the plasma structure consists of a bulk diffusive region, a thin layer governed by electron inertia, a thinner sublayer controlled by ion inertia, and the non-neutral Debye sheath. The solution of the main inertial layer yields that the electron azimuthal energy near the wall is larger than the electron thermal energy, making electron resistivity effects non-negligible. The electron Boltzmann relation is satisfied only in the very vicinity of the Debye sheath edge. Ion collisionality effects are irrelevant in the magnetized regime. Simple scaling laws for plasma production and particle and energy fluxes to the wall are derived.

  11. Divergence at neutral and non-neutral loci in Drosophila buzzatii populations and their hybrids

    DEFF Research Database (Denmark)

    Andersen, Ditte Holm; Pertoldi, Cino; Loeschcke, Volker

    2008-01-01

    The impact of intraspecific hybridisation on fitness and morphological traits depends on the history of natural selection and genetic drift, which may have led to differently coadapted gene-complexes in the parental populations. The divergence at neutral and non-neutral loci between populations can...... populations of Drosophila buzzatii, one between populations from Argentina and the Canary Islands (separated for 200 years), and the other between populations from Argentina and Australia (separated for 80 years). We observed the highest divergence at neutral loci between the Argentinean and Canary Island...

  12. Observation of transverse and longitudinal modes in non-neutral electron clouds confined in a magnetic mirror

    International Nuclear Information System (INIS)

    Eckhouse, S.; Fisher, A.; Rostoker, N.

    1979-01-01

    Electrostatic modes on non-neutral electron clouds confined in a magnetic mirror field have been investigated. The cloud contains 2 x 10 11 electrons at an average kinetic energy of 0.3 MeV for a magnetic field with a peak intensity of 9 kG at the midplane. It was found that the cloud is moving azimuthally as well as longitudinally. The azimuthal motion has an m=1 spatial nature. The longitudinal modes have a more complicated nature, but their frequency equals that of the azimuthal mode

  13. The central column structure in SPHEX

    International Nuclear Information System (INIS)

    Duck, R.C.; French, P.A.; Browning, P.K.; Cunningham, G.; Gee, S.J.; al-Karkhy, A.; Martin, R.; Rusbridge, M.G.

    1994-01-01

    SPHEX is a gun injected spheromak in which a magnetised Marshall gun generates and maintains an approximately axisymmetric toroidal plasma within a topologically spherical flux conserving vessel. The central column has been defined as a region of high mean floating potential, f > up to ∼ 150 V, aligned with the geometric axis of the device. It has been suggested that this region corresponds to the open magnetic flux which is connected directly to the central electrode of the gun and links the toroidal annulus (in which f > ∼ 0 V). Poynting vector measurements have shown that the power required to drive toroidal current in the annulus is transmitted out of the column by the coherent 20 kHz mode which pervades the plasma. Measurements of the MHD dynamo in the column indicate an 'antidynamo' electric field due to correlated fluctuations in v and B at the 20 kHz mode frequency which is consistent with the time-averaged Ohm's Law. On shorting the gun electrodes, the density in the column region decays rapidly leaving a 'hole' of radius R c ∼ 7 cm. This agrees with the estimated dimension of the open flux from mean internal B measurements and axisymmetric force-free equilibrium modelling, but is considerably smaller than the radius of ∼ 13 cm inferred from the time-averaged potential. In standard operating conditions the gun delivers a current of I G ∼ 60 kA at V G ∼ 500 V for ∼ 1 ms, driving a toroidal current of I t ∼ 60 kA. Ultimately we wish to understand the mechanism which drives toroidal current in the annulus; the central column is of interest because of the crucial role it plays in this process. (author) 8 refs., 6 figs

  14. Nonneutralizing antibodies against factor VIII and risk of inhibitor development in severe hemophilia A.

    Science.gov (United States)

    Cannavò, Antonino; Valsecchi, Carla; Garagiola, Isabella; Palla, Roberta; Mannucci, Pier Mannuccio; Rosendaal, Frits R; Peyvandi, Flora

    2017-03-09

    The development of anti-factor VIII (FVIII) neutralizing antibodies (inhibitors) is the major complication in hemophilia A. Nonneutralizing antibodies (NNAs) have been detected in hemophilia patients and also in unaffected individuals. The aim of this study was to assess the prevalence of NNAs and to evaluate whether their presence is associated with the development of inhibitors in a cohort of previously untreated or minimally treated patients with hemophilia A; plasma samples of 237 patients with severe hemophilia A enrolled in the SIPPET trial were collected before any exposure to FVIII concentrates and analyzed for the presence of anti-FVIII NNAs. Patients were observed for the development of neutralizing antibodies. NNAs were found in 18 (7.6%) of 237 patients at screening, and there was a clear age gradient. Of those with NNAs, 7 patients subsequently developed an inhibitor for a cumulative incidence of 45.4% (95% confidence interval [CI], 19.5% to 71.3%); among the 219 patients without NNAs, 64 (29%) developed an inhibitor (cumulative incidence, 34.0%; 95% CI, 27.1%-40.9%). In Cox regression analyses, patients with NNAs at screening had an 83% higher incidence of inhibitor development than patients without NNAs (hazard ratio [HR], 1.83; 95% CI, 0.84-3.99). For high-titer inhibitors, the incidence rate had an almost threefold increase (HR, 2.74; 95% CI, 1.23-6.12). These associations did not materially change after adjustment. The presence of anti-FVIII NNAs in patients with severe hemophilia A who were not previously exposed to FVIII concentrates is associated with an increased incidence of inhibitors. © 2017 by The American Society of Hematology.

  15. A periodic plasma waveguide accelerator

    International Nuclear Information System (INIS)

    Cole, F.T.

    1985-01-01

    The increasing cost of synchrotrons and storage rings has given new interest in the search for new methods of acceleration. The primary goal of this search is very large accelerating fields, because the cost of an accelerator to reach TeV energies is dominated by costs that scale with length. Very large electric fields are possible in plasmas and in lasers and many geometries are being studied that make use of plasmas, lasers, or combinations of them. In a plasma accelerator, the plasma can have several different functions. It may act as a medium for the propagation of accelerating electric-field waves. In addition, these waves may also act as a source of the energy needed to accelerate particles. Accelerators using various waves in plasmas have been built and studied in many laboratories. The device proposed here is an attempt to separate the two functions of providing a medium and providing an energy source. A relatively low-energy electron beam is used as a non-neutral plasma only to make a slow-wave medium for the propagation of an externally generated wave. The wave is a TM electromagnetic wave and the device may be thought of as a conventional electron linear accelerator with the evacuated volume and metallic envelope replaced by the electron beam. A separate second beam, which may be electrons or heavier particles, is accelerated. The application in mind here is a single-pass collider

  16. Time correlation between plasma behaviour and soft x-ray emission in a plasma focus

    International Nuclear Information System (INIS)

    Hirano, Katsumi; Tagaya, Yutaka; Shimoda, Katsuji; Okabe, Yushiro; Yamamoto, Toshikazu

    1986-01-01

    Soft X-rays emitted from a plasma focus are investigated experimentally. In contrast to single-pulsive burst of neutron, hard X-rays, ion- and electron beams, the soft X-rays are observed from the collapse phase to the decay phase of the plasma column, and have typically three successive peaks in its signal. Each peak corresponds to the maximum compression, the disruption and the decay phase of plasma column. It is revealed that the first and the second peaks are radiated by plasma itself, whereas the third peak is caused by emission from the inner electrode face. (author)

  17. Plasma focus breeder

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1981-09-01

    Instead of using linear accelerators, it is possible to breed fissile fuels with the help of high current plasma focus device. A mechanism of accelerating proton beam in plasma focus device to high energy would be a change of inductance in plasma column because of rapid growth of plasma instability. A possible scheme of plasma focus breeder is also proposed. (author)

  18. Kinetics of plasma membrane electron transport in a pulmonary endothelial cell-column.

    Science.gov (United States)

    Olson, L E; Merker, M P; Bongard, R D; Brantmeier, B M; Audi, S H; Linehan, J H; Dawson, C A

    1998-01-01

    Thiazine dyes such as toluidine blue O (TBO) are reduced at the luminal endothelial surface. The purpose of this study was to determine the rate of this reaction in endothelial cells in culture. A multiple indicator dilution method was used to measure the reaction kinetics during transient passage of a TBO-containing bolus through a chromatographic column filled with bovine pulmonary arterial endothelial cells grown on microcarrier beads (cell-column). A bolus containing TBO and an inert extracellular reference indicator (FITC-Dextran) was injected upstream of the cell-column, and the indicator concentrations were measured downstream using on-line photodetection. The effects of column flow rate, PO2, and TBO concentration were studied. The fraction of TBO reduced upon passage through the cell-column decreased with increasing flow indicating that the reaction rate rather than TBO delivery controlled TBO reduction. The fraction of TBO reduced did not change with PO2 or dose in the ranges studied. TBO reduction was about 10 times that for steady state TBO sequestration by these cells which, along with the lack of a PO2 effect indicates that the rapid rate of reduction is not the rate-limiting step in steady state sequestration.

  19. Wave propagation in plasma-filled wave-guide

    International Nuclear Information System (INIS)

    Leprince, Philippe

    1966-01-01

    This research thesis reports the study of wave propagation along a plasma column without external magnetic field. The author first present and comment various theoretical results, and dispersion curves plotted for the main modes (particularly, the bipolar mode). He tries to define fundamental magnitudes which characterise a plasma-filled wave-guide. He reports the comparison of some experimental results with the previous theoretical results. Based on the study of the bipolar mode, the author develops a method of measurement of plasma column density. In the last part, the author reports the study of the resonance of a plasma-containing cavity. Several resonances are highlighted and new dispersion curves are plotted by using a varying length cavity. He also addresses the coupling of plasma modes with guide modes, and thus indicates the shape of Brillouin diagrams for a plasma-filled wave-guide. Moreover, some phenomena highlighted during plasma column density measurements by using the cavity method could then be explained [fr

  20. Study of the plasma column in hollow-electrode arc; Etude de la colonne de plasma dans un arc a electrodes creuses

    Energy Technology Data Exchange (ETDEWEB)

    Cano, R; Mattioli, M; Zanfagna, B [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

    1966-07-01

    A steady state hollow electrodes arc has been built. The density of the plasma column obtained varies between 1.5 10{sup 13} cm{sup -3} and 8.10{sup 14} cm{sup -3} when the argon feed rate is varied from 0.2 and 30 l/h S.T.P. and the corresponding values of the electron temperature vary from at least 15 eV to 1 eV. Three diagnostic methods have been utilized: electrostatic probes, far-infrared emission (wavelength between 10 and 0.1 mm) and microwave techniques utilizing either the transmitted or the reflected wave. The results obtained are described in detail and compared. Limits of utilization of the different techniques are given. (authors) [French] On decrit les mesures effectuees sur une decharge a electrodes creuses fonctionnant en regime continu. Pour un debit d'argon variable entre 0,2 et 30 l/h N.T.P. la colonne de plasma obtenue a une densite qui peut varier entre 1,5.10{sup 13} cm{sup -3} et 8.10{sup 14} cm{sup -3} et une temperature electronique comprise entre au moins 15 eV et 1 eV (les densites plus elevees correspondent aux temperatures plus faibles). Trois methodes de diagnostic ont ete utilisees: sondes electrostatiques, emission dans l'infrarouge lointain (longueurs d'onde comprise entre 10 mm et 0,1 mm) et mesures en hyperfrequences avec ({lambda} = 2, 4, 3 et 8,6 mm en utilisant l'onde reflechie ou transmise par le plasma. Les resultats obtenus sont decrits en detail et compares entre eux. Des limites d'utilisation des differentes techniques sont donnees. (auteurs)

  1. Electrostatic storage ring with focusing provided by the space charge of an electron plasma

    International Nuclear Information System (INIS)

    Pacheco, J. L.; Ordonez, C. A.; Weathers, D. L.

    2013-01-01

    Electrostatic storage rings are used for a variety of atomic physics studies. An advantage of electrostatic storage rings is that heavy ions can be confined. An electrostatic storage ring that employs the space charge of an electron plasma for focusing is described. An additional advantage of the present concept is that slow ions, or even a stationary ion plasma, can be confined. The concept employs an artificially structured boundary, which is defined at present as one that produces a spatially periodic static field such that the spatial period and range of the field are much smaller than the dimensions of a plasma or charged-particle beam that is confined by the field. An artificially structured boundary is used to confine a non-neutral electron plasma along the storage ring. The electron plasma would be effectively unmagnetized, except near an outer boundary where the confining electromagnetic field would reside. The electron plasma produces a radially inward electric field, which focuses the ion beam. Self-consistently computed radial beam profiles are reported.

  2. Determination of the total concentration of highly protein-bound drugs in plasma by on-line dialysis and column liquid chromatography: application to non-steroidal anti-inflammatory drugs.

    NARCIS (Netherlands)

    Herraez-Hernandez, R.; van de Merbel, N.C.; Brinkman, U.A.T.

    1995-01-01

    The potential of on-line dialysis as a sample preparation procedure for compounds highly bound to plasma proteins is evaluated, using non-steroidal anti-inflammatory drugs as model compounds and column liquid chromatography as the separation technique. Different strategies to reduce the degree of

  3. Determination of the total concentration of highly protein-bound drugs in plasma by on-line dialysis and column liquid chromatography : application to non-steroidal anti-inflammatory drugs

    NARCIS (Netherlands)

    Herráez-Hernández, R; van de Merbel, N C; Brinkman, U A

    1995-01-01

    The potential of on-line dialysis as a sample preparation procedure for compounds highly bound to plasma proteins is evaluated, using non-steroidal anti-inflammatory drugs as model compounds and column liquid chromatography as the separation technique. Different strategies to reduce the degree of

  4. Algebraic motion of vertically displacing plasmas

    Science.gov (United States)

    Pfefferlé, D.; Bhattacharjee, A.

    2018-02-01

    The vertical motion of a tokamak plasma is analytically modelled during its non-linear phase by a free-moving current-carrying rod inductively coupled to a set of fixed conducting wires or a cylindrical conducting shell. The solutions capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the surrounding vacuum vessel. The plasma shape and profiles are assumed not to vary during the vertical drifting phase such that the plasma column behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented to come in contact with the wall due to steep effective potential barriers created by the induced Eddy currents. Resistivity in the wall allows the equilibrium point to drift towards the vessel on the slow timescale of flux penetration. The initial exponential motion of the plasma, understood as a resistive vertical instability, is succeeded by a non-linear "sinking" behaviour shown to be algebraic and decelerating. The acceleration of the plasma column often observed in experiments is thus concluded to originate from an early sharing of toroidal current between the core, the halo plasma, and the wall or from the thermal quench dynamics precipitating loss of plasma current.

  5. PRICE RIGIDITY AND MONETARY NON-NEUTRALITY IN DEVELOPING COUNTRIES: EVIDENCE FROM NIGERIA

    Directory of Open Access Journals (Sweden)

    Nathaniel E. Urama

    2013-04-01

    Full Text Available In an attempt to find out the degree of monetary non-neutrality in Nigeria we started from finding out the size of price rigidity in the country. Computation with Ball and Romer method showed that price rigidity is optimal decision for firms in Nigeria only when the menu cost is well above 2.28% of the firm’s revenue which is on the high side, showing the likelihood of weak price rigidity in the country. Confirming this, the IRFs of the SVAR shows that the response of inflation to nominal shock has only one period lag. These combined results led to a small though persistent response of output to the nominal shock. The result of the study therefore points towards large nominal and small real effect of monetary policy in Nigeria and conclude that monetary policy will be a better option for contractionary plan but not for an expansionary plan.

  6. End shape effects on the mθ=1 diocotron instability in hollow electron columns

    International Nuclear Information System (INIS)

    Kabantsev, A. A.; Driscoll, C. F.

    1999-01-01

    Magnetically confined hollow columns of electrons exhibit a robust exponential m θ =1 diocotron instability, whereas standard 2-D fluid theory predicts at most algebraic growth. This discrepancy suggests that experimental subtleties such as finite axial length of the plasma column must be considered. Here, we present a systematic analysis of our experiments to determine the detailed influence of the plasma end curvature on the observed diocotron instability. Observed dependencies of unstable mode frequency, growth rate and spatial eigenfunction as a function of the plasma end curvature are in quantitative (factor-of-two) agreement with recent quasi-2D extension of the fluid theory

  7. Toward sub-Kelvin resistive cooling and non destructive detection of trapped non-neutral electron plasma

    Science.gov (United States)

    Di Domizio, S.; Krasnický, D.; Lagomarsino, V.; Testera, G.; Vaccarone, R.; Zavatarelli, S.

    2015-01-01

    A resonant circuit tuned to a particular frequency of the motion of charged particles stored in a Penning trap and connected to a low noise amplifier allows, at the same time, cooling and non destructive detection of the particles. Its use is widely diffused when single or few particles are stored near the centre of a hyperbolic Penning trap. We present a consistent model that predicts the shape of the induced signal when the tuned circuit is used to detect and cool the axial motion of a cold non neutral plasma stored in an open-ended cylindrical Penning trap. The model correctly accounts for the not negligible axial plasma size. We show that the power spectrum of the signal measured across the tuned circuit provides information about the particle number and insights about the plasma temperature. We report on the design of a HEMT-based cryogenic amplifier working at 14.4 MHz and 4.2 K and the results of the noise measurements. We have measured a drain current noise in the range from 6 to 17 pA/√Hz, which corresponds to an increase of the tuned circuit equivalent temperature of at maximum 0.35 K. The cryogenic amplifier has a very low power consumption from few tens to few hundreds of μW corresponding to a drain current in the range 100-800 μ A. An additional contribution due to the gate noise has been identified when the drain current is below 300 μA above that value an upper limit of the increase of the equivalent tuned circuit temperature due to this contribution of 0.02 K has been obtained. These features make the tuned circuit connected to this amplifier a promising device for detecting and cooling the axial motion of an electron plasma when the Penning trap is mounted inside a dilution refrigerator.

  8. Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures

    International Nuclear Information System (INIS)

    Cremaschini, Claudio; Stuchlík, Zdeněk

    2014-01-01

    The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed

  9. Transition from gas to plasma kinetic equilibria in gravitating axisymmetric structures

    Energy Technology Data Exchange (ETDEWEB)

    Cremaschini, Claudio; Stuchlík, Zdeněk [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezručovo nám.13, CZ-74601 Opava (Czech Republic)

    2014-04-15

    The problem of the transition from gas to plasma in gravitating axisymmetric structures is addressed under the assumption of having initial and final states realized by kinetic Maxwellian-like equilibria. In astrophysics, the theory applies to accretion-disc scenarios around compact objects. A formulation based on non-relativistic kinetic theory for collisionless systems is adopted. Equilibrium solutions for the kinetic distribution functions describing the initial neutral matter and the resulting plasma state are constructed in terms of single-particle invariants and expressed by generalized Maxwellian distributions. The final plasma configuration is related to the initial gas distribution by the introduction of appropriate functional constraints. Qualitative aspects of the solution are investigated and physical properties of the system are pointed out. In particular, the admitted functional dependences of the fluid fields carried by the corresponding equilibrium distributions are determined. Then, the plasma is proved to violate the condition of quasi-neutrality, implying a net charge separation between ions and electrons. This result is shown to be independent of the precise realization of the plasma distribution function, while a physical mechanism able to support a non-neutral equilibrium state is proposed.

  10. Development of a 130-mA, 75-kV high voltage column for high-intensity dc proton injectors

    International Nuclear Information System (INIS)

    Sherman, J.; Arvin, A.; Hansborough, L.; Hodgkins, D.; Meyer, E.; Schneider, J.D.; Stevens, R.R. Jr.; Zaugg, T.

    1997-01-01

    A reliable high-voltage (HV) column has been developed for dc proton injectors with applications to high-intensity cw linacs. The HV column is coupled with a microwave-driven plasma generator to produce a 75-keV, 110-mA dc proton beam. Typical proton fraction from this source is 85--90%, requiring the HV column and accelerating electrodes to operate with a 130-mA hydrogen-ion beam current. A glow-discharge, which was caused by the ion source axial magnetic field, was initially observed in the HV column. This problem was solved by scaling the electron production processes, the magnetic field, and the HV column pressure into a favorable regime. A subsequent 168 hour reliability run on the 75-keV injector showed that the ion source (plasma generator and HV column) has >98% beam availability

  11. Algebraic motion of vertically displacing plasmas

    Science.gov (United States)

    Bhattacharjee, Amitava; Pfefferle, David; Hirvijoki, Eero

    2017-10-01

    The vertical displacement of tokamak plasmas is modelled during the non-linear phase by a free-moving current-carrying rod coupled to a set of fixed conducting wires and a cylindrical conducting shell. The models capture the leading term in a Taylor expansion of the Green's function for the interaction between the plasma column and the vacuum vessel. The plasma is assumed not to vary during the VDE such that it behaves as a rigid body. In the limit of perfectly conducting structures, the plasma is prevented from coming in contact with the wall due to steep effective potential barriers by the eddy currents, and will hence oscillate at Alfvénic frequencies about a given force-free position. In addition to damping oscillations, resistivity allows for the column to drift towards the vessel on slow flux penetration timescales. The initial exponential motion of the plasma, i.e. the resistive vertical instability, is succeeded by a non-linear sinking behaviour, that is shown analytically to be algebraic and decelerative. The acceleration of the plasma column often observed in experiments is thus conjectured to originate from an early sharing of toroidal current between the core, the halo plasma and the wall or from the thermal quench dynamics precipitating loss of plasma current

  12. Paul Trap Simulator Experiment (PTSX) to simulate intense beam propagation through a periodic focusing quadrupole field

    International Nuclear Information System (INIS)

    Davidson, Ronald C.; Efthimion, Philip C.; Gilson, Erik; Majeski, Richard; Qin, Hong

    2002-01-01

    The Paul Trap Simulator Experiment (PTSX) is under construction at the Princeton Plasma Physics Laboratory to simulate intense beam propagation through a periodic quadrupole magnetic field. In the Paul trap configuration, a long nonneutral plasma column is confined axially by dc voltages on end cylinders at z=+L and z=-L, and transverse confinement is provided by segmented cylindrical electrodes with applied oscillatory voltages ±V 0 (t) over 90 deg. segments. Because the transverse focusing force is similar in waveform to that produced by a discrete set of periodic quadrupole magnets in a frame moving with the beam, the Paul trap configuration offers the possibility of simulating intense beam propagation in a compact laboratory facility. The experimental layout is described, together with the planned experiments to study beam mismatch, envelope instabilities, halo particle production, and collective wave excitations

  13. Paul Trap Simulator Experiment (PTSX) to simulate intense beam propagation through a periodic focusing quadrupole field

    Science.gov (United States)

    Davidson, Ronald C.; Efthimion, Philip C.; Gilson, Erik; Majeski, Richard; Qin, Hong

    2002-01-01

    The Paul Trap Simulator Experiment (PTSX) is under construction at the Princeton Plasma Physics Laboratory to simulate intense beam propagation through a periodic quadrupole magnetic field. In the Paul trap configuration, a long nonneutral plasma column is confined axially by dc voltages on end cylinders at z=+L and z=-L, and transverse confinement is provided by segmented cylindrical electrodes with applied oscillatory voltages ±V0(t) over 90° segments. Because the transverse focusing force is similar in waveform to that produced by a discrete set of periodic quadrupole magnets in a frame moving with the beam, the Paul trap configuration offers the possibility of simulating intense beam propagation in a compact laboratory facility. The experimental layout is described, together with the planned experiments to study beam mismatch, envelope instabilities, halo particle production, and collective wave excitations.

  14. Dusty plasma phase in a steady state plasma device

    International Nuclear Information System (INIS)

    Liang Xiaoping; Zheng Jian; Ma Jinxiu; Liu Wangdong; Zhuang Ge; Xie Jinlin; Wang Congrong; Yu Changxuan

    2000-01-01

    A DC discharge dusty plasma device used for study of waves in dusty plasma is introduced. A dusty plasma column is produced with about 30 cm in length and about 8.4 cm in diameter. The electron saturation current of Langmuir probe is obviously decreasing while the dust grains are present in the plasma. The negative charge on dust grains is directly proportional to the rotation rate of the dispenser. And the dust grains carry up to 40% of the negative charges in the whole plasma

  15. Plasminogen activator inhibitor-1 removal using dextran sulphate columns. Evidence of PAI-1 homeostasis.

    LENUS (Irish Health Repository)

    Maher, Vincent M G

    2009-08-01

    Patients with high plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels are prone to develop thrombosis. Lowering PAI-1 levels may offer a therapeutic option and help to better understand PAI-1 metabolism. We examined the effect on plasma PAI-1 levels of LDL-apheresis using dextran sulphate (DS) columns in 12 patients (9 male, 3 female, 49 +\\/- 10 years) with heterozygous familial hypercholesterolaemia and coronary artery disease. One plasma volume equivalent (2.3-4.0 l) was treated during each procedure (at flow rates of 23 +\\/- 2 ml\\/min). Lipids and PAI-1 antigen levels were measured in plasma before and immediately after 19 aphereses (once in 7 patients, twice in 3 patients and three times in 2 patients) and also at 3 and 7 days post apheresis in five of these patients and in the column eluates from 8 of these patients. DS-apheresis reduced plasma cholesterol (50 +\\/- 8%), triglyceride (45 +\\/- 27%), apolipoprotein B (59 +\\/- 10%) and PAI-1 antigen levels from 10.2 +\\/- 5.2 to 6.0 +\\/- 3.1 ng\\/ml (P = 0.005). The PAI-I changes were independent of circadian variation. PAI-I bound to the DS-columns (3.51 +\\/- 1.03 ng\\/ml filtered plasma) and the percent of filtered PAI-1 that was bound correlated inversely (r = -0.81, P < 0.02) with basal PAI-1 levels indicating a high affinity saturable binding process. In four patients, plasma PAI-1 levels post-apheresis were higher than expected based on the amount of PAI-removed by the DS columns. The difference between the expected and actual PAI-1 level post apheresis, reflecting PAI-1 secretion or extracellular redistribution, correlated inversely with basal PAI-1 levels (r = -0.83, P = 0.01). PAI-1 levels returned to baseline pre-apheresis values 7 days post apheresis. PAI-1 antigen may be removed from plasma without adverse effect, resulting temporarily in its extracellular redistribution and restoration to baseline levels over one week. PAI-1 redistribution particularly when baseline pre

  16. FACTORES PARA LA NO NEUTRALIDAD DE LA EVALUACIÓN DE LA CALIDAD DE LA EDUCACIÓN SUPERIOR (FACTORS FOR NON-NEUTRALITY OF THE EVALUATION OF THE HIGHER EDUCATION QUALITY

    Directory of Open Access Journals (Sweden)

    Vizcarra Herles Nina Eleonor

    2011-08-01

    Full Text Available Resumen:En el presente ensayo, los autores con base en la revisión de fuentes bibliográficas, abordan el tema de la no neutralidad de la evaluación de la calidad de la educación superior, se identifican factores de la no neutralidad en la evaluación y en la calidad relacionados con: el referente (modelo de referencia utilizado para la evaluación, las dimensiones explicativo-relacionales de la calidad y las demandas de calidad formuladas por actores sociales; estos factores expresan el propósito del evaluador, componente ideológico que determina la no neutralidad de la evaluación de la calidad. Se infiere que para los sistemas nacionales de evaluación la definición y la mejora de la calidad de la educación superior compromete la participación multisectorial.Abstract: In this essay, the authors based on a review of literature sources, address the issue of non-neutrality of the evaluation of the quality of higher education, identify factors of non-neutrality in the evaluation and quality related to: the reference model used for evaluation, the explanatory-relational dimensions of quality and quality demands made by social actors; these factors express the purpose of evaluator, ideological component that determines the non-neutrality of quality assessment. It is inferred that for the national assessment systems; the definition and the improving of the quality of higher education undertake multi-stakeholder participation.

  17. Plasma target output from a magnetically augmented, gas-injected, washer-stack plasma gun

    International Nuclear Information System (INIS)

    Osher, J.E.

    1982-01-01

    This article describes a new washer-stack gun design developed for the application of plasma target production for the startup of neutral-beam trapping in a fusion research magnetic confinement system. The gun is a Mo anode type that is D 2 injected and has an auxiliary pulsed magnet for control of plasma-flux mapping. One of the principal features of 2--10-ms duration pulses for gun operation in a suitable magnetic field is the formation of an arc column along magnetic field lines from the gun's central cathode electrode to the vacuum chamber walls (at common anode potential). The primary power output from a 5.0-cm-i.d. gun is typically carried along this arc column by a stream of approximately 2000 A of 50--250-eV electrons. This primary stream of relatively low-density energetic electrons efficiently ionizes the injected gas, forming a quasi-dc source of denser secondary plasma of approx.10 13 /cm 3 at a few eV, which is able to flow or diffuse away along a somewhat larger column of magnetic field lines. In plasma-target production tests on a test stand, a gun operated at a D 2 gas flow of 22 Torr ls -1 yielded 250 A of equivalent plasma flow

  18. Column-to-column packing variation of disposable pre-packed columns for protein chromatography.

    Science.gov (United States)

    Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois

    2017-12-08

    In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  19. Thermal equilibrium of pure electron plasmas across a central region of magnetic surfaces

    Science.gov (United States)

    Hahn, Michael; Pedersen, Thomas Sunn

    2009-06-01

    Measurements of the equilibria of plasmas created by emission from a biased filament located off the magnetic axis in the Columbia Non-neutral Torus (CNT) [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois et al., Fusion Sci. Technol. 50, 372 (2006)] show that such plasmas have equilibrium properties consistent with the inner surfaces being in a state of cross-surface thermal equilibrium. Numerical solutions to the equilibrium equation were used to fit the experimental data and demonstrate consistency with cross-surface thermal equilibrium. Previous experiments in CNT showed that constant temperatures across magnetic surfaces are characteristic of CNT plasmas, implying thermal confinement times much less than particle confinement times. These results show that when emitting off axis there is a volume of inner surfaces where diffusion into that region is balanced by outward transport, producing a Boltzmann distribution of electrons. When combined with the low thermal energy confinement time this is a cross-surface thermal equilibrium.

  20. Thermal equilibrium of pure electron plasmas across a central region of magnetic surfaces

    International Nuclear Information System (INIS)

    Hahn, Michael; Pedersen, Thomas Sunn

    2009-01-01

    Measurements of the equilibria of plasmas created by emission from a biased filament located off the magnetic axis in the Columbia Non-neutral Torus (CNT) [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois et al., Fusion Sci. Technol. 50, 372 (2006)] show that such plasmas have equilibrium properties consistent with the inner surfaces being in a state of cross-surface thermal equilibrium. Numerical solutions to the equilibrium equation were used to fit the experimental data and demonstrate consistency with cross-surface thermal equilibrium. Previous experiments in CNT showed that constant temperatures across magnetic surfaces are characteristic of CNT plasmas, implying thermal confinement times much less than particle confinement times. These results show that when emitting off axis there is a volume of inner surfaces where diffusion into that region is balanced by outward transport, producing a Boltzmann distribution of electrons. When combined with the low thermal energy confinement time this is a cross-surface thermal equilibrium.

  1. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    Science.gov (United States)

    Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

    2011-10-01

    In the cold-fluid dispersion relation ω =ωp/[1+(k⊥/kz)2]1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k⊥/kz. As a result, for any frequency ω plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz /dr=±(ωp2/ω2-1)1/2. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  2. Kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field based on the nonlinear Vlasov-Maxwell equations

    International Nuclear Information System (INIS)

    Davidson, R.C.; Chen, C.

    1997-08-01

    A kinetic description of intense nonneutral beam propagation through a periodic solenoidal focusing field B sol (rvec x) is developed. The analysis is carried out for a thin beam with characteristic beam radius r b much-lt S, and directed axial momentum γ b mβ b c (in the z-direction) large compared with the transverse momentum and axial momentum spread of the beam particles. Making use of the nonlinear Vlasov-Maxwell equations for general distribution function f b (rvec x,rvec p,t) and self-consistent electrostatic field consistent with the thin-beam approximation, the kinetic model is used to investigate detailed beam equilibrium properties for a variety of distribution functions. Examples are presented both for the case of a uniform solenoidal focusing field B z (z) = B 0 = const. and for the case of a periodic solenoidal focusing field B z (z + S) = B z (z). The nonlinear Vlasov-Maxwell equations are simplified in the thin-beam approximation, and an alternative Hamiltonian formulation is developed that is particularly well-suited to intense beam propagation in periodic focusing systems. Based on the present analysis, the Vlasov-Maxwell description of intense nonneutral beam propagation through a periodic solenoidal focusing field rvec B sol (rvec x) is found to be remarkably tractable and rich in physics content. The Vlasov-Maxwell formalism developed here can be extended in a straightforward manner to investigate detailed stability behavior for perturbations about specific choices of beam equilibria

  3. A unified Monte Carlo interpretation of particle simulations and applications to nonneutral plasmas

    International Nuclear Information System (INIS)

    Aydemir, A.Y.

    1993-09-01

    Using a ''Monte Carlo interpretation'' a particle simulations, a general description of low-noise techniques is developed in terms well-known Monte Carlo variance reduction methods. Some of these techniques then are applied to linear and nonlinear studies of pure electron plasmas in cylindrical geometry, with emphasis on the generation and nonlinear evolution of electron vortices. Long-lived l = 1 and l and l = 2 vortices, and others produced by unstable diocotron modes in hollow profiles, are studies. It is shown that low-noise techniques make it possible to follow the linear evolution and saturation of even the very weakly unstable resonant diocotron modes

  4. Determination of lansoprazole enantiomers in dog plasma by column-switching liquid chromatography with tandem mass spectrometry and its application to a preclinical pharmacokinetic study.

    Science.gov (United States)

    Wang, Hao; Sun, Yantong; Meng, Xiangjun; Yang, Bo; Wang, Jian; Yang, Yan; Gu, Jingkai

    2015-09-01

    Lansoprazole, a selective proton pump inhibitor, has a chiral benzimidazole sulfoxide structure and is used for the treatment of gastric acid hypersecretory related diseases. To investigate its stereoselective pharmacokinetics, a column-switching liquid chromatography with tandem mass spectrometry method was developed for the determination of lansoprazole enantiomers in dog plasma using (+)-pantoprazole as an internal standard. After a simple protein precipitation procedure with acetonitrile, matrix components left behind after sample preparation were further eliminated from the sample by reversed-phase chromatography on a C18 column. The fluent was fed to a chiral column for the separation of lansoprazole enantiomers. Baseline separation of lansoprazole enantiomers was achieved on a Chiralcel OZ-RH column using acetonitrile/0.1% formic acid in water (35:65, v/v) as the mobile phase at 40°C. The linearity of the calibration curves ranged from 3 to 800 ng/mL for each enantiomer. Intra- and inter-day precisions ranged from 2.1 to 7.3% with an accuracy of ±1.7% for (+)-lansoprazole, and from 1.6 to 6.9% with an accuracy of ±3.5% for (-)-lansoprazole, respectively. The validated method was successfully applied for the stereoselective pharmacokinetic study of lansoprazole in beagle dog after intravenous infusion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Theoretical models of non-Maxwellian equilibria for one-dimensional collisionless plasmas

    Science.gov (United States)

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

    2016-12-01

    It is ideal to use exact equilibrium solutions of the steady state Vlasov-Maxwell system to intialise collsionless simulations. However, exact equilibrium distribution functions (DFs) for a given macroscopic configuration are typically unknown, and it is common to resort to using `flow-shifted' Maxwellian DFs in their stead. These DFs may be consistent with a macrosopic system with the target number density and current density, but could well have inaccurate higher order moments. We present recent theoretical work on the `inverse problem in Vlasov-Maxwell equilibria', namely calculating an exact solution of the Vlasov equation for a specific given magnetic field. In particular, we focus on one-dimensional geometries in Cartesian (current sheets) coordinates.1. From 1D fields to Vlasov equilibria: Theory and application of Hermite Polynomials: (O. Allanson, T. Neukirch, S. Troscheit and F. Wilson, Journal of Plasma Physics, 82, 905820306 (2016) [28 pages, Open Access] )2. An exact collisionless equilibrium for the Force-Free Harris Sheet with low plasma beta: (O. Allanson, T. Neukirch, F. Wilson and S. Troscheit, Physics of Plasmas, 22, 102116 (2015) [11 pages, Open Access])3. Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field (O. Allanson, F. Wilson and T. Neukirch, (2016)) (accepted, Physics of Plasmas)

  6. Experimental studies of stable confined electron clouds using Gabor lenses

    CERN Document Server

    Meusel, O.; Glaeser, B.; Schulte, K.

    2013-04-22

    Based on the idea of D. Gabor [1] space charge lenses are under investigation to be a powerful focussing device for intense ion beams. A stable confined electron column is used to provide strong radially symmetric electrostatic focussing, e.g. for positively charged ion beams. The advantages of Gabor lenses are a mass independent focussing strength, space charge compensation of the ion beam and reduced magnetic or electric fields compared to conventional focussing devices. Collective phenomena of the electron cloud result in aberrations and emittance growth of the ion beam. The knowledge of the behaviour of the electron cloud prevents a decrease of the beam brilliance. Numerical models developed to describe the electron confinement and dynamics within a Gabor lens help to understand the interaction of the ion beam with the electron column and show the causes of non-neutral plasma instabilities. The diagnosis of the electron cloud properties helps to evaluate the numerical models and to investigate the influen...

  7. Creation of a confined plasma column and diagnostic arrangement for X-ray laser development

    International Nuclear Information System (INIS)

    Voorhees, D.; Keane, C.; Milchberg, H.; Semet, A.; Skinner, C.; Suckewer, S.

    1983-01-01

    We present the experimental arrangement for our soft X-ray laser development program. We describe the various components of the apparatus. These consist of a CO 2 laser, focusing components, solenoidal magnet, targets, pulsed gas mechanisms, diagnostics and data acquisition systems. The experiment utilizes a CO 2 laser with an output energy up to 1 KJ to create a plasma column confined in a solenoidal magnetic field (B less than or equal to 100 KG). Two alternative methods are used to focus the laser energy into the vacuum chamber of the experiment. The first uses a system of two flat mirrors to reflect the 25 cm annular beam to a NaCl lens. The beam then passes through a NaCl window forming the entrance to the vacuum system. A second method consists of a two chamber vacuum system enclosing two flat mirrors and a third spherical mirror. The incident beam passes into the vacuum through one NaCl window eliminating the losses encountered at the NaCl lens of the previously described system. In each case the focused beam interacts with either a solid target, a gas target, or a combination of the two. With gas targets we have used orifices to create a pressure gradient near the point of laser interaction. For some experiments gas is introduced into the system via a fast solenoid valve or piezoactuated puff valve. A calibrated piezoelectronic transducer is utilized to characterize the gas pressure as a function of time and position along the magnetvacuum chamber axis. The resultant pressure profiles enable us to synchronize the firing of the gas valve, magnet and laser to achieve optimum densities in the plasma

  8. Stereoselective determination of unchanged and glucuroconjugated eliprodil, a new anti-ischaemic drug, in human plasma and urine by precolumn derivatization and column-switching high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Malavasi, B; Ripamonti, M; Rouchouse, A; Ascalone, V

    1996-04-05

    An HPLC method was developed and validated for the determination in human plasma and urine of the enantiomers of eliprodil, (+/-)-alpha-(4-chlorophenyl)-4[(4-fluorophenyl) methyl]piperidine-1-ethanol hydrochloride, a new anti-ischaemic agent administered as a racemate. Both enantiomers are present in human plasma in unchanged and glucuroconjugated form, whereas only the glucuroconjugated form is excreted into urine; as a consequence, such metabolites in human plasma and urine should be submitted to enzymatic deconjugation with beta-glucuronidase (Escherichia coli) before being extracted. The general method involves a liquid-liquid extraction of eliprodil and internal standard from alkalinized plasma or urine with n-hexane, evaporation of the organic phase and derivatization with (S)-(+)-naphthylethyl isocyanate to give carbamate diastereoisomeric derivatives of (S)-(+)- and (R)-(-)-eliprodil and internal standard; after evaporation of the derivatizing mixture and dissolution of the residue in a small volume of phosphate buffer-acetonitrile (60:40, v/v), an aliquot is injected into a column-switching HPLC system. The derivatized sample extract is purified on a precolumn filled with C8-bonded silica material, which is flushed with acetonitrile-water, then diastereoisomers of eliprodil and the internal standard are automatically transferred by the mobile phase to the analytical column. The analytical column is a C8 type, specially deactivated for basic compounds, the mobile phase is 0.025 M phosphate buffer (pH 2.6)-methanol-acetonitrile (42:2:56) at a flow-rate of 1.2 ml min-1 and fluorimetric detector operating at lambda ex = 275 nm and lambda em = 336 nm is used. The retention times, under these conditions, are about 16 and 17 min for (S)-(+)- and (R)-(-)-eliprodil diastereoisomers, respectively, and about 19 min for the first-eluted diastereoisomer of the internal standard. During the analysis time, the precolumn, reset in a different path from that of the

  9. The Current-Driven, Ion-Acoustic Instability in a Collisionless Plasma

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1979-01-01

    The current-driven, ion-acoustic instability was investigated by means of an experiment performed in a collisionless plasma produced in a single-ended Q-machine. Reflections at the ends of the plasma column gave rise to a standing wave. Parameters of the instability were investigated, and it was ......, and it was demonstrated that the fluctuations in the plasma column behave as a classical Van der Pol oscillator. Accurate measurements of the growth rate of the instability can be performed by making explicit use of the particular properties of such a system.......The current-driven, ion-acoustic instability was investigated by means of an experiment performed in a collisionless plasma produced in a single-ended Q-machine. Reflections at the ends of the plasma column gave rise to a standing wave. Parameters of the instability were investigated...

  10. The influence of the nitrogen admixture on the evolution of a deuterium pinch column

    Energy Technology Data Exchange (ETDEWEB)

    Kubes, P.; Cikhardtova, B.; Cikhardt, J.; Klir, D.; Kravarik, J.; Rezac, K.; Kortanek, J. [Czech Technical University, 166-27 Prague (Czech Republic); Paduch, M.; Zielinska, E. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); Sadowski, M. J. [Institute of Plasma Physics and Laser Microfusion, 01-497 Warsaw (Poland); National Centre for Nuclear Research, 05-400 Otwock-Świerk (Poland); Tomaszewski, K. [ACS Ltd., 01-497 Warsaw (Poland)

    2016-08-15

    The application of a mixture of nitrogen and deuterium for the gas-puffing along the anode axis in deuterium plasma-focus discharges, as carried out at megaampere-level currents, enabled observations of the filamentary structure, and the decrease in the transformation velocity of the plasma column to be performed. It made possible to investigate the instability evolution during the production of hard X-rays and fast neutrons in more detail. The constriction of a plasma column transforms itself during the final phase of the compression into one or more small dense plasmoid-like structures which are separated by narrow necks. During the next phase, these structures start to decay by an expansion, in which a part of the plasma volume maintains its compactness. This evolution is explained by an increase and later decrease in the internal poloidal current component by reconnections of the associated magnetic lines, which are responsible for the acceleration of electron and ion beams.

  11. Control of plasma column horizontal position in TBR-1

    International Nuclear Information System (INIS)

    Tuszel, A.G.; Rincoski, C.R.M.

    1990-01-01

    The TBR-1 is a small tokamak built at the Physics Institute of the University of Sao Paulo. It was originally designed with a simple vertical field power supply made of one fast capacitor bank for vertical current build-up and one slow capacitor bank for flat-top phase, without any control but the adjustable initial voltages of the capacitors. With such an elementary system, the plasma cannot be held in the center of the vacuum vessel for the whole duration of the plasma. This led to a suboptimal performance with easy disruptions. A control system was designed to hold the plasma centered in the radial coordinate. (Author)

  12. Remote operation of the vertical plasma stabilization @ the GOLEM tokamak for the plasma physics education

    Energy Technology Data Exchange (ETDEWEB)

    Svoboda, V., E-mail: svoboda@fjfi.cvut.cz [Faculty of Nuclear Sciences and Physical Engineering CTU Prague, CZ-115 19 (Czech Republic); Kocman, J.; Grover, O. [Faculty of Nuclear Sciences and Physical Engineering CTU Prague, CZ-115 19 (Czech Republic); Krbec, J.; Stöckel, J. [Faculty of Nuclear Sciences and Physical Engineering CTU Prague, CZ-115 19 (Czech Republic); Institute of Plasma Physics AS CR, CZ-182 21 Prague (Czech Republic)

    2015-10-15

    Graphical abstract: * Understandable remote operation of a vertical plasma position control system in the tokamak GOLEM for educational purposes.* Two combinable modes of real-time plasma position control: position based feedback and a pre-defined waveform.* More than 20% plasma life prolongation with plasma position control in feedback mode. - Highlights: • Understandable remote operation of a vertical plasma position control system in the tokamak GOLEM for educational purposes. • Two combinable modes of real-time plasma position control: position based feedback and a pre-defined waveform. • More than 20% plasma life prolongation with plasma position control in feedback mode. - Abstract: The GOLEM tokamak at the Czech Technical University has been established as an educational tokamak device for domestic and foreign students. Remote participation in the scope of several laboratory practices, plasma physics schools and workshops has been successfully performed from abroad. A new enhancement allowing understandable remote control of vertical plasma position in two modes (i) predefined and (ii) feedback control is presented. It allows to drive the current in the stabilization coils in any time-dependent scenario, which can include as a parameter the actual plasma position measured by magnetic diagnostics. Arbitrary movement of the plasma column in a vertical direction, stabilization of the plasma column in the center of the tokamak vessel as well as prolongation/shortening of plasma life according to the remotely defined request are demonstrated.

  13. Three Dimensional Double Layers in Magnetized Plasmas

    DEFF Research Database (Denmark)

    Jovanovic, D.; Lynov, Jens-Peter; Michelsen, Poul

    1982-01-01

    Experimental results are presented which demonstrate the formation of fully three dimensional double layers in a magnetized plasma. The measurements are performed in a magnetized stationary plasma column with radius 1.5 cm. Double layers are produced by introducing an electron beam with radius 0.......4 cm along the magnetic field from one end of the column. The voltage drop across the double layer is found to be determined by the energy of the incoming electron beam. In general we find that the width of the double layer along the external magnetic field is determined by plasma density and beam...

  14. Mechanized Sephadex LH-20 multiple column chromatography as a prerequisite for automated multi-steroid radioimmunoassays

    International Nuclear Information System (INIS)

    Sippell, W.G.; Bidlingmaier, F.; Knorr, D.

    1978-01-01

    To establish a procedure for the simultaneous determination of all major corticosteroid hormones and their immediate biological precursors in the same plasma sample, two different mechanized methods for the simultaneous isolation of aldosterone (A), corticosterone (B), 11-deoxycorticosterone (DOC), progesterone (P), 17-hydroxyprogesterone (17-OHP), 11-deoxycortisol (S), cortisol (F) and cortisone (E) from the methylene chloride extracts of 0.1 to 2.0ml plasma samples have been developed. In method I, steroids are separated with methylene chloride:methanol=98:2 as solvent system on 60-cm Sephadex LH-20 columns, up to eight of which are eluted in parallel using a multi-channel peristaltic pump and individual flow-rate control (40ml/h) by capillary valves and micro-flowmeters. Method II, on the other hand, utilizes the same solvent system on ten 75-cm LH-20 columns which are eluted in reversed flow simultaneously by a ten-channel, double-piston pump that precisely maintains an elution flow rate of 40ml/h in every column. In both methods, eluate fractions of each of the isolated steroids are automatically pooled and collected from all parallel columns by one programmable linear fraction collector. As a result of the high reproducibility of the elution patterns, both between different parallel columns and between 30 to 40 consecutive elutions, mean recoveries of tritiated steroids including extraction are 60 to 84% after a single separation and still over 50% after an additional separation on 40-cm LH-20 columns, with coefficients of variation below 15% (method II). Thus, the eight steroids can be completely isolated from each of ten plasma extracts within 3 to 4 hours, yielding 80 samples readily prepared for subsequent quantitation by radioimmunoassay. (author)

  15. Rapid determination of telmisartan in human plasma by HPLC using a monolithic column with fluorescence detection and its application to a bioequivalence study.

    Science.gov (United States)

    Zhang, He; Jiang, Yunyun; Wen, Jun; Zhou, Tingting; Fan, Guorong; Wu, Yutian

    2009-11-01

    A rapid HPLC method using a monolithic column with fluorescence detection has been developed for determination of telmisartan in human plasma. Sample preparation was done by protein precipitation with acetonitrile and naproxen was used as IS. The compounds were detected by fluorescence detection, using an excitation wavelength of 300 nm and emission wavelength of 385 nm. Calibration curves of telmisartan were linear in the range of 1-200 ng/mL. The assay was high throughput, sensitive and precise, and it was successfully applied to a bioequivalence study of two formulations of telmisartan.

  16. Cold plasmas

    International Nuclear Information System (INIS)

    Franz, G.

    1990-01-01

    This textbook discusses the following topics: Phenomenological description of a direct current glow discharge; the plasma (temperature distribution and measurement, potential variation, electron energy distribution function, charge neutralization, wall potentials, plasma oscillations); Production of charge carriers (ions, electrons, ionization in the cathode zone, negative glowing zone, Faraday dark space, positive column, anode zone, hollow cathode discharges); RF-discharges (charge carrier production, RF-Shields, scattering mechanisms); Sputtering (ion-surface interaction, kinetics, sputtering yield and energy distribution, systems and conditions, film formation and stresses, contamination, bias techniques, multicomponent film deposition, cohesion, magnetrons, triode systems, plasma enhanced chemical vapor deposition); Dry etching (sputter etching, reactive etching, topography, process control, quantitative investigations); Etching mechanisms (etching of Si and SiO 2 with CF 4 , of III/V-compound-semiconductors, combination of isotrope and anisotrope etching methods, surface cleaning); ion beam systems (applications, etching); Dyclotron-resonance-systems (electron cyclotron resonance systems, whistler-sources and 'resonant inductive plasma etching'); Appendix (electron energy distribution functions, Bohm's transition zone, plasma oscillations, scattering cross sections and mean free path, metastable states, Child-Langmuir-Schottky equation, loss mechanisms, charge carrier distribution in the positive column, breakdown at high frequencies, motion in a magnetic field, skin depth of an electric field for a HF-discharge, whistler waves, dispersion relations for plane wave propagation). (orig.) With 138 figs

  17. Effect of mobilities and electric field on the stability of magnetized positive column

    International Nuclear Information System (INIS)

    Dogra, V.K.; Uberoi, M.S.

    1983-01-01

    The effect of ratio of the mobilities of electrons and ions and non-dimensional electric field, on the stability of magnetized positive column for all unstable modes is studied in a self-consistent formulation for the perturbations of plasma density and electric potential. The minimum non-dimensional electric field at which magnetized positive column becomes unstable for different ratios of the mobilities of electrons and ions is also investigated. (author)

  18. Hydrodynamic optical-field-ionized plasma channels

    Science.gov (United States)

    Shalloo, R. J.; Arran, C.; Corner, L.; Holloway, J.; Jonnerby, J.; Walczak, R.; Milchberg, H. M.; Hooker, S. M.

    2018-05-01

    We present experiments and numerical simulations which demonstrate that fully ionized, low-density plasma channels could be formed by hydrodynamic expansion of plasma columns produced by optical field ionization. Simulations of the hydrodynamic expansion of plasma columns formed in hydrogen by an axicon lens show the generation of 200 mm long plasma channels with axial densities of order ne(0 ) =1 ×1017cm-3 and lowest-order modes of spot size WM≈40 μ m . These simulations show that the laser energy required to generate the channels is modest: of order 1 mJ per centimeter of channel. The simulations are confirmed by experiments with a spherical lens which show the formation of short plasma channels with 1.5 ×1017cm-3≲ne(0 ) ≲1 ×1018cm-3 and 61 μ m ≳WM≳33 μ m . Low-density plasma channels of this type would appear to be well suited as multi-GeV laser-plasma accelerator stages capable of long-term operation at high pulse repetition rates.

  19. Isotopic enrichment in a plasma centrifuge

    International Nuclear Information System (INIS)

    Del Bosco, E.; Dallaqua, R.S.; Ludwig, G.O.; Bittencourt, J.A.

    1986-05-01

    A rotating fully ionized plasma column was produced in a vacuum-arc centrifuge. The apparatus is described and new results for the rotational velocity and isotope enrichment of carbon and metal plasmas are shown. The ion rotation velocity is derived from electrostatic probes measurents and from the azimuthal displacement of the material deposited behind of a narrow slit. The isotope enrichment is measured with a modified quadrupole mass spectrometer, which determines, in situ, the relative abundance of the isotopes at the end of the plasm column at various radil positions. (Author) [pt

  20. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    International Nuclear Information System (INIS)

    Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

    2011-01-01

    In the cold-fluid dispersion relation ω=ω p /[1+(k perpendicular /k z ) 2 ] 1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k perpendicular /k z . As a result, for any frequency ω p , there are infinitely many degenerate waves, all having the same value of k perpendicular /k z . On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz/dr=±(ω p 2 /ω 2 -1) 1/2 . Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  1. Behaviour of laser-produced plasma in a uniform magnetic field

    International Nuclear Information System (INIS)

    Okada, Shigefumi; Sato, Kohnosuke; Sekiguchi, Tadashi.

    1979-11-01

    A column of a laser-produced plasma is successfully made in a uniform magnetic field. The radius of the column increases and then decreases (bouncing motion). On the surface of this plasma column, where the steep density gradient exists with the scale length shorter than the ion Larmor radius, an azimuthal modulation appears in the plasma luminosity. This is indicative of the flute-like instability with the azimuthal wave number; k sub(perpendicular) -- 4 x 10 3 B sup(0.8) (in the MKSA system of units). The dispersion equation based on the linearized Vlasov equation with the local approximation is derived and the occurrence of the lower-hybrid-drift instability is predicted. A fairly good agreement between the theory and experiments is seen. (author)

  2. Ion accumulation in an electron plasma confined on magnetic surfaces

    International Nuclear Information System (INIS)

    Berkery, John W.; Marksteiner, Quinn R.; Pedersen, Thomas Sunn; Kremer, Jason P.

    2007-01-01

    Accumulation of ions can alter and may destabilize the equilibrium of an electron plasma confined on magnetic surfaces. An analysis of ion sources and ion content in the Columbia Non-neutral Torus (CNT) [T.S. Pedersen, J.P. Kremer, R.G. Lefrancois, Q. Marksteiner, N. Pomphrey, W. Reiersen, F. Dahlgreen, and X. Sarasola, Fusion Sci. Technol. 50, 372 (2006)] is presented. In CNT ions are created preferentially at locations of high electron temperature, near the outer magnetic surfaces. A volumetric integral of n e ν iz gives an ion creation rate of 2.8x10 11 ions/s. This rate of accumulation would cause neutralization of a plasma with 10 11 electrons in about half a second. This is not observed experimentally, however, because currently in CNT ions are lost through recombination on insulated rods. From a steady-state balance between the calculated ion creation and loss rates, the equilibrium ion density in a 2x10 -8 Torr neutral pressure, 7.5x10 11 m -3 electron density plasma in CNT is calculated to be n i =6.2x10 9 m -3 , or 0.8%. The ion density is experimentally measured through the measurement of the ion saturation current on a large area probe to be about 6.0x10 9 m -3 for these plasmas, which is in good agreement with the predicted value

  3. SEMIAUTOMATED SOLID-PHASE EXTRACTION PROCEDURE FOR DRUG SCREENING IN BIOLOGICAL-FLUIDS USING THE ASPEC SYSTEM IN COMBINATION WITH CLEAN SCREEN DAU COLUMNS

    NARCIS (Netherlands)

    CHEN, XH; FRANKE, JP; ENSING, K; WIJSBEEK, J; DEZEEUW, RA

    1993-01-01

    The use of a semi-automated solid-phase extraction system (ASPEC) for the screening of drugs in plasma and urine on a single mixed-mode column (Clean Screen DAU) is described. The processes of column preconditioning, sample application, column wash, pH adjustment and elution of the drugs were

  4. Modeling Stone Columns.

    Science.gov (United States)

    Castro, Jorge

    2017-07-11

    This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.

  5. Post column derivatisation analyses review. Is post-column derivatisation incompatible with modern HPLC columns?

    Science.gov (United States)

    Jones, Andrew; Pravadali-Cekic, Sercan; Dennis, Gary R; Shalliker, R Andrew

    2015-08-19

    Post Column derivatisation (PCD) coupled with high performance liquid chromatography or ultra-high performance liquid chromatography is a powerful tool in the modern analytical laboratory, or at least it should be. One drawback with PCD techniques is the extra post-column dead volume due to reaction coils used to enable adequate reaction time and the mixing of reagents which causes peak broadening, hence a loss of separation power. This loss of efficiency is counter-productive to modern HPLC technologies, -such as UHPLC. We reviewed 87 PCD methods published from 2009 to 2014. We restricted our review to methods published between 2009 and 2014, because we were interested in the uptake of PCD methods in UHPLC environments. Our review focused on a range of system parameters including: column dimensions, stationary phase and particle size, as well as the geometry of the reaction loop. The most commonly used column in the methods investigated was not in fact a modern UHPLC version with sub-2-micron, (or even sub-3-micron) particles, but rather, work-house columns, such as, 250 × 4.6 mm i.d. columns packed with 5 μm C18 particles. Reaction loops were varied, even within the same type of analysis, but the majority of methods employed loop systems with volumes greater than 500 μL. A second part of this review illustrated briefly the effect of dead volume on column performance. The experiment evaluated the change in resolution and separation efficiency of some weak to moderately retained solutes on a 250 × 4.6 mm i.d. column packed with 5 μm particles. The data showed that reaction loops beyond 100 μL resulted in a very serious loss of performance. Our study concluded that practitioners of PCD methods largely avoid the use of UHPLC-type column formats, so yes, very much, PCD is incompatible with the modern HPLC column. Copyright © 2015. Published by Elsevier B.V.

  6. High sensitivity and selectivity in quantitative analysis of drugs in biological samples using 4-column multidimensional micro-UHPLC-MS enabling enhanced sample loading capacity.

    Science.gov (United States)

    de Vries, Ronald; Vereyken, Liesbeth; François, Isabelle; Dillen, Lieve; Vreeken, Rob J; Cuyckens, Filip

    2017-10-09

    Sensitivity is often a critical parameter in quantitative bioanalyses in drug development. For liquid-chromatography-based methods, sensitivity can be improved by reducing the column diameter, but practical sensitivity gains are limited by the reduced sample loading capacity on small internal diameter (I.D.) columns. We developed a set-up that has overcome these limitations in sample loading capacity. The set-up uses 4 columns with gradually decreasing column diameters along the flow-path (2.1 → 1 → 0.5 → 0.15 mm). Samples are pre-concentrated on-line on a 2.1 mm I.D. trapping column and back flushed to a 1 mm I.D. UHPLC analytical column and separated. The peak(s) of interest are transferred using heartcutting to a second trapping column (0.5 mm I.D.), which is back-flushed to a 0.15 mm I.D. micro-UHPLC analytical column for orthogonal separation. The proof of concept of the set-up was demonstrated by the simultaneous analysis of midazolam and 1'-hydroxy midazolam in plasma by injection of 80 μL of protein precipitated plasma. The 4-column funnel set-up proved to be robust and resulted in a 10-50 times better sensitivity compared to a trap-elute approach and 250-500 fold better compared to direct micro-UHPLC analysis. A lower limit of quantification of 100 fg/mL in plasma was obtained for both probe compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. On the Self-Focusing of Whistler Waves in a Radial Inhomogeneous Plasma

    DEFF Research Database (Denmark)

    Balmashnov, A. A.

    1980-01-01

    The process of whistler wave self-focusing is experimentally investigated. It was found that a whistler wave propagating along the plasma column with a density crest excites a longitudinal wave of the same frequency propagating across the external magnetic field. The amplitude modulation of the l......The process of whistler wave self-focusing is experimentally investigated. It was found that a whistler wave propagating along the plasma column with a density crest excites a longitudinal wave of the same frequency propagating across the external magnetic field. The amplitude modulation...... of the latter wave is accompanied by a density modification, which leads to trapping of the whistler wave in a density trough in the center of the plasma column....

  8. Broadly-Reactive Neutralizing and Non-neutralizing Antibodies Directed against the H7 Influenza Virus Hemagglutinin Reveal Divergent Mechanisms of Protection.

    Directory of Open Access Journals (Sweden)

    Gene S Tan

    2016-04-01

    Full Text Available In the early spring of 2013, Chinese health authorities reported several cases of H7N9 influenza virus infections in humans. Since then the virus has established itself at the human-animal interface in Eastern China and continues to cause several hundred infections annually. In order to characterize the antibody response to the H7N9 virus we generated several mouse monoclonal antibodies against the hemagglutinin of the A/Shanghai/1/13 (H7N9 virus. Of particular note are two monoclonal antibodies, 1B2 and 1H5, that show broad reactivity to divergent H7 hemagglutinins. Monoclonal antibody 1B2 binds to viruses of the Eurasian and North American H7 lineages and monoclonal antibody 1H5 reacts broadly to virus isolates of the Eurasian lineage. Interestingly, 1B2 shows broad hemagglutination inhibiting and neutralizing activity, while 1H5 fails to inhibit hemagglutination and demonstrates no neutralizing activity in vitro. However, both monoclonal antibodies were highly protective in an in vivo passive transfer challenge model in mice, even at low doses. Experiments using mutant antibodies that lack the ability for Fc/Fc-receptor and Fc/complement interactions suggest that the protection provided by mAb 1H5 is, at least in part, mediated by the Fc-fragment of the mAb. These findings highlight that a protective response to a pathogen may not only be due to neutralizing antibodies, but can also be the result of highly efficacious non-neutralizing antibodies not readily detected by classical in vitro neutralization or hemagglutination inhibition assays. This is of interest because H7 influenza virus vaccines induce only low hemagglutination inhibiting antibody titers while eliciting robust antibody titers as measured by ELISA. Our data suggest that these binding but non-neutralizing antibodies contribute to protection in vivo.

  9. An electrodynamical model for the ion behaviour in the final plasma focus stages

    International Nuclear Information System (INIS)

    Zambreanu, V.; Doloc, C.M.

    1992-01-01

    Plasma focus devices (PFDs) are strong sources of fusion neutrons but the problem of which interactions are responsible for the fusion reactions is still open since neither of the proposed theoretical models has been confirmed experimentally. A model for the trajectories of the deuteron ions in a configuration of selfconsistent electromagnetic fields is proposed starting from an empirical plasma model which describes the plasma focus collapse and column phases. The proposed model is only electrodynamical under the assumption of a uniform current density and an infinite length of the plasma column, not taking into account the fluid characteristics of the plasma. (author)

  10. On the spatial behavior of background plasma in different background pressure in CPS device

    International Nuclear Information System (INIS)

    Samantaray, Subrata; Paikaray, Rita; Sahoo, Gourishankar; Das, Parthasarathi; Ghosh, Joydeep; Sanyasi, Amulya Kumar

    2015-01-01

    Blob formation and transport is a major concern for investigators as it greatly reduces the efficiency of the devices. Initial results from CPS device confirm the role of fast neutrals inside the bulk plasma in the process of blob formation and transport. 2-D simulation of curvature and velocity shear instability in plasma structures suggest that in the presence of background plasma, secondary instability do not grow non-linearly to a high level and stabilizes the flow. Adiabaticity effect also creates a radial barrier for interchange modes. In the absence of background plasma the blob fragments even at the modest level of viscosity. The fast neutrals outside bulk plasma supposed to stabilize the system. The background plasma set up is aimed at creating fast neutrals outside main plasma column, hence; the background plasma set up is done in CPS device. The spatial behavior of plasma column in between electrodes is different for different base pressure in CPS device. The spatial variation of electron temperature of plasma column between electrodes is presented in this communication. Electron temperature is measured from emission spectroscopy data. The maximum electron temperature (line averaged) is ∼ 1.5 eV. (author)

  11. Electromagnetic Wave Transmittance Control using Anisotropic Plasma Lattice

    Science.gov (United States)

    Matlis, Eric; Corke, Thomas; Hoffman, Anthony

    2017-11-01

    Experiments of transmission through a lattice array of plasma columns have shown an absorption band close to the plasma frequency at 14 GHz. The beam was oriented at a 35° incident angle to the planar plasma cell. These experiments were designed to determine if the observed absorption was the result of the isotropic plasma medium or that of an anisotropic metamaterial. Transmission of the microwave energy was not consistent with an isotropic material in which absorption would monotonically increase below the plasma frequency. The experimental results are supported by an anisotropic model which was developed for the plasma permittivity using an effective medium approximation. The plasma columns were modeled as uniform rods with permittivity described by a Drude model while the components of the permittivity tensor was calculated using the Maxwell-Garnett effective medium theory. Electron densities of n = 4 x1012 cm-3 were assumed which is consistent with prior experimental measurements. This model confirms the existence of non-zero imaginary wave vector k in a narrow region centered about 14 GHz.

  12. The role of plasma proteins in formation of obstructive protamine complexes

    International Nuclear Information System (INIS)

    De Paulis, R.; Mohammad, S.F.; Chiariello, L.; Morea, M.; Olsen, D.B.

    1991-01-01

    Formation of complexes between heparin and protamine (in saline), or heparin, plasma proteins, and protamine (in plasma) was assessed by measurements of light transmission through different test solutions. To examine the formation of these complexes, 125I-labeled protamine was used. Addition of 125I-protamine to plasma or blood resulted in the sedimentation of 125I-protamine in the form of insoluble complexes. This complex formation was not affected by the presence of heparin, suggesting that protamine-plasma protein interaction may be primarily responsible for precipitation of 125I-protamine. To assess the capability of these complexes to obstruct the pulmonary circulation, an in vitro experimental model was developed. Citrated serum, plasma, blood, or saline were allowed to flow through a glass bead column with the help of a peristaltic pump. A pressure transducer positioned before the column allowed pressure measurements at a constant flow rate during the experiment. Mixing of protamine with plasma or blood prior to their passage through the glass bead column resulted in a significant increase in pressure suggesting that the column was being clogged with insoluble complexes. The increase in pressure occurred both in the presence and absence of heparin in plasma or blood. Under identical experimental conditions, the increase in pressure was insignificant when protamine was added to saline or serum regardless of whether heparin was present or absent. This was further confirmed by the use of 125I-protamine. These observations suggest that protamine forms insoluble complexes with certain plasma proteins. Based on these observations, it is hypothesized that following intravenous administration, protamine immediately forms complexes in circulating blood

  13. Assembly for connecting the column ends of two capillary columns

    International Nuclear Information System (INIS)

    Kolb, B.; Auer, M.; Pospisil, P.

    1984-01-01

    In gas chromatography, the column ends of two capillary columns are inserted into a straight capillary from both sides forming annular gaps. The capillary is located in a tee out of which the capillary columns are sealingly guided, and to which carrier gas is supplied by means of a flushing flow conduit. A ''straight-forward operation'' having capillary columns connected in series and a ''flush-back operation'' are possible. The dead volume between the capillary columns can be kept small

  14. Undamped electrostatic plasma waves

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, F.; Perrone, D.; Veltri, P. [Dipartimento di Fisica and CNISM, Universita della Calabria, 87036 Rende (CS) (Italy); Califano, F.; Pegoraro, F. [Dipartimento di Fisica and CNISM, Universita di Pisa, 56127 Pisa (Italy); Morrison, P. J. [Institute for Fusion Studies and Department of Physics, University of Texas at Austin, Austin, Texas 78712-1060 (United States); O' Neil, T. M. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

    2012-09-15

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

  15. Undamped electrostatic plasma waves

    International Nuclear Information System (INIS)

    Valentini, F.; Perrone, D.; Veltri, P.; Califano, F.; Pegoraro, F.; Morrison, P. J.; O'Neil, T. M.

    2012-01-01

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,ω R ) plane (ω R being the real part of the wave frequency and k the wavenumber), away from the well-known “thumb curve” for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

  16. Simulation and Experimental Study of Arc Column Expansion After Ignition in Low-Voltage Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    MA Qiang; RONG Mingzhe; WU Yi; XU Tiejun; SUN Zhiqiang

    2008-01-01

    The dynamicprocess of arc pressure and corresponding arc column expansion, which is the main feature after arc ignition and has a significant effect on the breaking behaviour of low -voltage circuit breakers, is studied. By constructing a three dimensional mathematical model of air arc plasma and adopting the Control Volume Method, the parameters of arc plasma including temperature and pressure axe obtained. The variations of pressure field and temperature field with time are simulated. The result indicates that there are six stages for the process of arc column expansion according to the variation of pressure in arc chamber. In the first stage, the maximal pressure locates in the region close to cathode, and in the second stage the maximal pressure shifts to the region close to the anode. In the third stage, the pressure difference between the middle of arc column and the ambient gas is very large, so the arc column begins to expand apparently. In the fourth stage, the pressure wave propagates towards both ends and the maximal pressure appears at the two ends when the pressure wave reaches both sidewalls. In the fifth stage, the pressure wave is reflected and collides in the middle of the arc chamber. In the last stage, the propagation and reflection of pressure wave will repeat several times until a steady burning state is reached. In addition, the experimental results of arc column expansion, corresponding to the arc pressure variation, are presented to verify the simulation results.

  17. Intergrain Coupling in Dusty-Plasma Coulomb Crystals

    International Nuclear Information System (INIS)

    Mohideen, U.; Smith, M.A.; Rahman, H.U.; Rosenberg, M.; Mendis, D.A.

    1998-01-01

    We have studied the lattice structure of dusty-plasma Coulomb crystals formed in rectangular conductive grooves as a function of plasma temperature and density. The crystal appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. A simple phenomenological model wherein the intergrain spacing results from an attractive electric-field-induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal. copyright 1998 The American Physical Society

  18. D.C.-arc plasma generator for nonequilibrium plasmachemical processes

    International Nuclear Information System (INIS)

    Kvaltin, J.

    1990-06-01

    The analysis is made of the conditions for generation of nonequilibrium plasma in a plasmachemical reactor, and the design is described of a d.c. arc plasma generator based on the integral criterion. Results of measuring potentials on the plasma column of this generator are presented. (author)

  19. Determination of alpidem, an imidazopyridine anxiolytic, and its metabolites by column-switching high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Flaminio, L; Ripamonti, M; Ascalone, V

    1994-05-13

    Alpidem, 6-chloro-2-(4-chlorophenyl)-N,N-dipropylimidazo[1,2-a]pyridine- 3-acetamide, is an anxiolytic imidazopyridine that undergoes a first-pass elimination after oral administration to humans; it is actively metabolized and three circulating metabolites have been identified in plasma due to N-dealkylation, oxidation or a combination of both processes. For the determination of the unchanged drug and its metabolites in human plasma, a column-switching HPLC method was developed. The method, based on solid-phase extraction (performed on-line), involves the automatic injection of plasma samples (200 microliters) on to a precolumn filled with C18 material, clean-up of the sample with water in order to remove protein and salts and transfer of the analytes to the analytical column (after valve switching) by means of the mobile phase. All the processes were performed in the presence of an internal standard, a compound chemically related to alpidem. During the analytical chromatography, the precolumn was flushed with different solvents and after regeneration with water, it was ready for further injections. The analytical column was a C8 type and the mobile phase was acetonitrile-methanol-phosphate buffer solution (45:15:45, v/v/v) at a flow-rate of 1.5 ml min-1. The column was connected to a fluorimetric detector operating at excitation and emission wavelengths of 255 and 423 nm, respectively. The limits of quantitation of alpidem and three metabolites were 2.5 and 1.5 ng ml-1, respectively, in human plasma.

  20. Saturation regime of the collisionless drift instability in a hydrogen plasma column

    International Nuclear Information System (INIS)

    Boissier, R.

    1982-09-01

    The saturation regime of the collisionless drift instability is observed in a steady state hydrogen column. The steady state parameters are observed to relax around the average values. A quasilinear model is proposed to describe the dynamics of wave growth and density gradient decay

  1. Diffusion Processes in the Positive Column in a longitudinal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, B [Royal Institute of Technology, Stockholm (Sweden)

    1958-07-01

    The purpose of the present investigation is to study diffusion across a magnetic field in a configuration which is free from short-circuiting effects such as those described by Simon. It provides the possibility of deciding whether collision or 'drain' diffusion is operative. For the purpose a long cylindrical plasma column with a homogeneous magnetic field along the axis has been chosen. The theoretical treatment is given. On the basis of the collision diffusion theory Tonks, Rokhlin, Cummings and Tonks and Fataliev have pointed out that a longitudinal magnetic field will reduce the losses of particles to the walls. Consequently, when the magnetic field is present, a lower electron temperature and a smaller potential drop along the plasma column should be required to sustain a certain ion density. The present experiment forms an extension of that of Bickerton and von Engel into a range where the Schottky theory is applicable in the absence of a magnetic field and where the applied magnetic field is still made strong enough to influence the electron temperature.

  2. Evolution of Excited Convective Cells in Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans; Juul Rasmussen, Jens; Sugai, H.

    1984-01-01

    Convective cells are excited externally in a fully ionized magnetized plasma and their space-time evolution is investigated by two-dimensional potential measurements. A positive cell is excited externally by control of the end losses in the 'scrape off' layer of a plasma column produced by surface...

  3. A variational principle for the plasma centrifuge

    International Nuclear Information System (INIS)

    Ludwig, G.O.

    1986-09-01

    A variational principle is derived which describes the stationary state of the plasma column in a plasma centrifuge. Starting with the fluid equations in a rotating frame the theory is developed using the method of irreversible thermodynamics. This formulation easily leads to an expression for the density distribution of the l-species at sedimentation equilibrium, taking into account the effect of the electric and magnetic forces. Assuming stationary boundary conditions and rigid rotation nonequilibrium states the condition for thermodynamic stability integrated over the volume of the system reduces, under certain restrictions, to the principle of minimum entropy production in the stationary state. This principle yields a variational problem which is equivalent to the original problem posed by the stationary fluid equations. The variational method is useful in achieving approximate solutions that give the electric potential and current distributions in the rotating plasma column consistent with an assumed plasma density profile. (Author) [pt

  4. Application of optimal control theory to laser heating of a plasma in a solenoidal magnetic field

    International Nuclear Information System (INIS)

    Neal, R.D.

    1975-01-01

    Laser heating of a plasma column confined by a solenoidal magnetic field is studied via modern optimal control techniques. A two-temperature, constant pressure model is used for the plasma so that the temperature and density are functions of time and location along the plasma column. They are assumed to be uniform in the radial direction so that refraction of the laser beam does not occur. The laser intensity used as input to the column at one end is taken as the control variable and plasma losses are neglected. The localized behavior of the plasma heating dynamics is first studied and conventional optimal control theory applied. The distributed parameter optimal control problem is next considered with minimum time to reach a specified final ion temperature criterion as the objective. Since the laser intensity can only be directly controlled at the input end of the plasma column, a boundary control situation results. The problem is unique in that the control is the boundary value of one of the state variables. The necessary conditions are developed and the problem solved numerically for typical plasma parameters. The problem of maximizing the space-time integral of neutron production rate in the plasma is considered for a constant distributed control problem where the laser intensity is assumed fixed at maximum and the external magnetic field is taken as a control variable

  5. Isotope separation by rotating plasmas

    International Nuclear Information System (INIS)

    Nicoli, C.

    1982-02-01

    A steady-state model of a fully ionized plasma column in a concentric cylindrical electrodes structures is proposed to study the plasma separation properties of its singly ionized ionic species, composed of two isotopes of the element. In this model (a one-fluid model) rotation is imparted to the plasma column through the J (vector) x B (vector) interaction. Radial pressure balance is mainly between the radial component of the J (vector) x B (vector) force and the pressure gradient plus centrifugal force and the azimutal component of the J (vector) x B (vector) force is balanced purely by viscous force. A pressure tensor 31 describes the viscoys effect and the heat balance provides an equation for temperature. A uranium gas with is two main isotopes (U 235 and U 238 ) was used for the ionic component of the plasma. The computing code to solve the resulting, system of equations in tems of density, temperature, and velocity as functions of the radial independent variable was set up to yield solutions satisfying null velocity conditions on both boundaries (inner and outer electrodes). (M.A.F.) [pt

  6. Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.

    Science.gov (United States)

    Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J

    2015-05-22

    Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Vortex formation during rf heating of plasma

    International Nuclear Information System (INIS)

    Motley, R.W.

    1980-05-01

    Experiments on a test plasma show that the linear theory of waveguide coupling to slow plasma waves begins to break down if the rf power flux exceeds approx. 30 W/cm 2 . Probe measurements reveal that within 30 μs an undulation appears in the surface plasma near the mouth of the twin waveguide. This surface readjustment is part of a vortex, or off-center convective cell, driven by asymmetric rf heating of the plasma column

  8. JCE Feature Columns

    Science.gov (United States)

    Holmes, Jon L.

    1999-05-01

    The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

  9. A restricted access material for rapid analysis of [11C]-labeled radiopharmaceuticals and their metabolites in plasma

    International Nuclear Information System (INIS)

    Gillings, Nic

    2009-01-01

    Introduction: Analysis of the radioactive components in plasma taken during positron emission tomography (PET) measurements is often vital for the correct quantification of the PET data. The described high-performance liquid chromatography (HPLC) method has been developed to provide a fast, sensitive and robust method for the measurement of plasma samples from PET studies using [ 11 C]-labeled radiopharmaceuticals. Methods: Unadulterated plasma samples were analyzed directly, following a simple filtration, by the use of a small extraction column, containing a restricted access material, combined with a monolithic analysis column in a column-switching HPLC system. Results: Up to 4 ml of plasma was analyzed by this method within 4.5-7 min in a fully automated process. Because of the rapid analysis, a large number of samples could be analyzed during a 90-min PET scan. The extraction column could be used for analysis of up to 500 ml of plasma before replacement was required. Conclusions: The described method is fast and robust and the large sample volumes allow for accurate determination of the radioactive components in plasma even at 90 min after injection of a [ 11 C]-labeled radiopharmaceutical.

  10. Measurement of toroidal plasma current in RF heated helical plasmas

    International Nuclear Information System (INIS)

    Besshou, Sakae

    1993-01-01

    This report describes the measurement of toroidal plasma current by a semiflexible Rogowski coil in a helical vacuum chamber. A Rogowski coil measures the toroidal plasma current with a resolution of 0.1 kA, frequency range of up to 1 kHz and sensitivity of 6.5 x 10 -9 V · s/A. We measured the spontaneous toroidal plasma current (from -1.2 to +1.2 kA) under electron cyclotron resonance heating at 0.94 T toroidal field in the Heliotron-E device. We found that the measured direction of toroidal plasma current changes its sign as in the predicted behavior of a neoclassical diffusion-driven bootstrap current, depending on the horizontal position of the plasma column. We explain the observed plasma currents in terms of the compound phenomenon of an ohmic current and a neoclassical diffusion-driven current. The magnitude of the neoclassical current component is smaller than the value predicted by a collisionless neoclassical theory. (author)

  11. Quantitative X-ray spectroscopy of sodium Z-pinch plasmas for Na/ne photopumping

    International Nuclear Information System (INIS)

    Burkhalter, P.G.; Mehlman, G.; Apruzese, J.P.; Newman, D.A.; Scherrer, V.E.; Young, F.C.; Stephanakis, S.J.; Hinshelwood, D.D.

    1990-01-01

    Spectra of sodium K-shell x-ray emission were measured for implosions of sodium-bearing plasmas produced on the Naval Research Laboratory Gamble II pulsed-power generator. Sodium fluoride from a capillary discharge provided the initial plasma for these fast Z-pinch implosions. Spatially-resolved images, corresponding to sodium K-shell x-rays from a 3 to 4 cm long plasma column, were recorded with a curved-crystal spectrograph. Non-uniform emission was observed along this column. The diameter of the plasma along the column (1-5 mm) was determined from time-integrated pinhole-camera images, and the duration of the x-ray emission (15-23 ns FWHM) was measured with a vacuum x-ray diode. Absolute emissivities were determined for X-rays from the n=2-1 and n=3-1 transitions in Na X and Na XI. Emissivities calculated using a collisional-radiative equilibrium model were fitted to these measurements to determine plasma temperatures of 230 to 550 eV and electron densities of 0.2 to 4.0 x 10 20 cm -3 at several locations along the plasma column. The slope of the recombination continuum was also used to determine temperatures of 200 to 300 eV and 200 to 400 eV for Na X and Na XI ions, respectively. Absolute intensity measurements of the n=2-1 line emissions from Na X and Na XI, averaged over the entire plasma length, indicated shot-to-shot variations of more than a factor of two in these implosions. (author)

  12. Evaluation of radioimmunological methods for assay of plasma and urinary aldosterone

    International Nuclear Information System (INIS)

    Pakarinen, A.; Koskinen, L.; Adlercreutz, H.

    1976-01-01

    Two radioimmunological methods for assay of plasma and urinary aldosterone were carefully evaluated. In the plasma method a radioimmunoassay is preceded by chromatography on a Sephadex LH-20 column. The method for urine includes a preextraction, hydrolysis of the acid-labile conjugates of aldosterone, and a radioimmunoassay. Both methods fulfill the criteria of reliability and are suitable for both routine and demanding research assays. The plasma method, using columns of double length is also applicable to analysis of aldosterone on plasma of newborn children, and pregnant females and in cord plasma. The concentration of plasma aldosterone in healthy subjects on an ad lib salt diet was 162 π+ 93 (S.D.) pmol/l in the supine position and 312 π+ 217 (S.D.) pmol/l upright. The urinary excretion of aldosterone in healthy subjects was 28.3 π+ 16.7 (S.D.) nmol/24 h. (Auth.)

  13. Orienting Block Copolymer Thin Films via Entropy and Surface Plasma Treatment

    Science.gov (United States)

    Ho, Rong-Ming; Lu, Kai-Yuan; Lo, Ting-Ya; Dehghan, Ashkan; Shi, An-Chang; Prokopios, Georgopanos; Avgeropoulos, Apostolos

    Controlling the orientation of nanostructured thin films of block copolymers (BCPs) is essential for next generation lithography. In the thin-film state, how to achieve the perpendicular orientation of the nanostructured microdomains remains challenging due to the interfacial effects from the air and also the substrate, especially for the blocks with silicon containing segments which usually have different surface energies, favoring parallel microdomain orientation. Here, we show that entropic effect can be used to control the orientation of BCP thin films. Specifically, we used the architecture of star-block copolymers consisting of polystyrene (PS) and poly(dimethylsiloxane) (PDMS) blocks to regulate the entropic contribution to the self-assembled nanostructures. Moreover, we aim to achieve the formation of perpendicular orientation from the air surface via surface plasma treatment to neutralize the interfacial energy difference. By combining the architecture effect (entropy effect) on BCP self-assembly and the surface plasma treatment (enthalpy effect), well-defined perpendicular PDMS microdomains in the PS-b-PDMS thin film can be formed from the bottom of non-neutral substrate and the top of the thin film surface, giving great potential for lithographic applications.

  14. Plasma flow measurements in the Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) and comparison with B2.5-Eirene modeling

    Science.gov (United States)

    Kafle, N.; Owen, L. W.; Caneses, J. F.; Biewer, T. M.; Caughman, J. B. O.; Donovan, D. C.; Goulding, R. H.; Rapp, J.

    2018-05-01

    The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) at Oak Ridge National Laboratory is a linear plasma device that combines a helicon plasma source with additional microwave and radio frequency heating to deliver high plasma heat and particle fluxes to a target. Double Langmuir probes and Thomson scattering are being used to measure local electron temperature and density at various radial and axial locations. A recently constructed Mach-double probe provides the added capability of simultaneously measuring electron temperatures ( T e), electron densities ( n e), and Mach numbers (M). With this diagnostic, it is possible to infer the plasma flow, particle flux, and heat flux at different locations along the plasma column in Proto-MPEX. Preliminary results show Mach numbers of 0.5 (towards the dump plate) and 1.0 (towards the target plate) downstream from the helicon source, and a stagnation point (no flow) near the source for the case where the peak magnetic field was 1.3 T. Measurements of particle flow and ne and Te profiles are discussed. The extensive coverage provided by these diagnostics permits data-constrained B2.5-Eirene modeling of the entire plasma column, and comparison with results of modeling in the high-density helicon plasmas will be presented.

  15. Computer simulation of plasma behavior in open-ended linear theta machines. Scientific report 81-5

    International Nuclear Information System (INIS)

    Stover, E.K.

    1981-04-01

    Zero-dimensional and one-dimensional fluid plasma computer models have been developed to study the behavior of linear theta pinch plasmas. Computer simulation results generated from these codes are compared with data obtained from two theta pinch experiments so that significant machine plasma behavior can be identified. The experiments examined are a collisional experiment, T/sub i/ approx. 50 eV, n/sub e/ approx. 10 17 cm -3 , where the plasma mean-free-path was significantly less than the plasma column length, and a hot ion species experiment, T/sub i/ approx. 3 keV, n/sub e/ approx. 10 16 cm -3 , where the ion mean-free-path was on the order of the plasma column length

  16. [Purification of arsenic-binding proteins in hamster plasma after oral administration of arsenite].

    Science.gov (United States)

    Wang, Wenwen; Zhang, Min; Li, Chunhui; Qin, Yingjie; Hua, Naranmandura

    2013-01-01

    To purify the arsenic-binding proteins (As-BP) in hamster plasma after a single oral administration of arsenite (iAs(III)). Arsenite was given to hamsters in a single dose. Three types of HPLC columns, size exclusion, gel filtration and anion exchange columns, combined with an inductively coupled argon plasma mass spectrometer (ICP MS) were used to purify the As-BP in hamster plasma. SDS-PAGE was used to confirm the arsenic-binding proteins at each purification step. The three-step purification process successfully separated As-BP from other proteins (ie, arsenic unbound proteins) in hamster plasma. The molecular mass of purified As-BP in plasma was approximately 40-50 kD on SDS-PAGE. The three-step purification method is a simple and fast approach to purify the As-BP in plasma samples.

  17. Preparation of Affinity Column Based on Zr4+ Ion for Phosphoproteins Isolation

    International Nuclear Information System (INIS)

    Lee, Seon Mi; Bae, In Ae; Park, Jung Hyen; Kim, Tae Dong; Choi, Seong Ho

    2009-01-01

    This paper has described about preparation of Zr 4+ affinity column based on the poly(styreneco- glycidyl methacrylate) prepared by emulsion polymerization of styrene and glycidyl methacrylate in order to isolate phosphopeptide. The Zr 4+ ions were introduced after the phophonation of an epoxy group on polymeric microspheres. The successful preparation of Zr 4+ -immobilized polymeric microsphere stationary phase was confirmed through Fourier transform infrared spectra, optical microscopy, scanning electron microscopy, X-ray photoelectron spectra and inductively coupled plasma-atomic emission spectrometer. The separation efficiency for Zr 4+ affinity column prepared by slurry packing was tested to phosphonated casein and dephosphonated casein. The resolution time (min) of the phosphonated casein was higher than that of dephosphated casein for Zr 4+ affinity polymeric microsphere by liquid chromatography. This Zr 4+ affinity column can be used for isolation of phosphonated casein from casein using liquid chromatography

  18. Investigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, M., E-mail: yajima.miyuki@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan); Ohno, N. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kajita, S. [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); De Temmerman, G. [ITER Organization, Route de Vinon sur Verdon, CS 90 046-13067 St Paul Lez Durance Cedex (France); Bystrov, K.; Bardin, S.; Morgan, T.W. [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Partner in the Trilateral Euregio Cluster, 5612 AJ Eindhoven (Netherlands); Masuzaki, S. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan)

    2016-11-15

    Arcing on fiber-formed nanostructured tungsten samples during ELM-like pulses was investigated using the superimposition of high power pulsed plasma on a steady state plasma with hydrogen gas in the linear plasma device Pilot-PSI. The ignition of arcing was observed when the floating potential of the samples was less than −75 V with sufficient heat flux. The surface observation showed that the arc spots were not in the center, but in the peripheral area of the plasma column. Considering the plasma potential profile in the Pilot-PSI, the arcing occurred at the position where the heat flux and the sheath potential drop are sufficiently large.

  19. Microwave power coupling in a surface wave excited plasma

    Directory of Open Access Journals (Sweden)

    Satyananda Kar

    2015-01-01

    Full Text Available In recent decades, different types of plasma sources have been used for various types of plasma processing, such as, etching and thin film deposition. The critical parameter for effective plasma processing is high plasma density. One type of high density plasma source is Microwave sheath-Voltage combination Plasma (MVP. In the present investigation, a better design of MVP source is reported, in which over-dense plasma is generated for low input microwave powers. The results indicate that the length of plasma column increases significantly with increase in input microwave power.

  20. Column Liquid Chromatography.

    Science.gov (United States)

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  1. A review on ion–ion plasmas created in weakly magnetized electronegative plasmas

    International Nuclear Information System (INIS)

    Aanesland, A; Bredin, J; Chabert, P

    2014-01-01

    Ion–Ion plasmas are electronegative plasmas where the electron density is several orders of magnitude lower than the negative ion density. These plasmas have been scarcely observed and investigated since the 1960s and are formed as a transient state of pulsed plasmas or in separate regions in magnetized plasmas. In this review we focus on the latter case of continuous formation of ion–ion plasmas created at the periphery of magnetized plasma columns or downstream localized magnetic barriers. We bring together and review experimental results already published elsewhere and complement them with new results to illustrate the physics important in ion–ion plasma formation and highlight in particular unanswered questions. We show that with a good design the density in the ion–ion region is dropping only by a factor of 2–3 from the initial plasma density. These plasmas can therefore be well suited for various ion source applications when both fluxes or beams of positive and negative ions are desired, and when electrons can cause harmful effects. (paper)

  2. Self-consistent modeling of radio-frequency plasma generation in stellarators

    Energy Technology Data Exchange (ETDEWEB)

    Moiseenko, V. E., E-mail: moiseenk@ipp.kharkov.ua; Stadnik, Yu. S., E-mail: stadnikys@kipt.kharkov.ua [National Academy of Sciences of Ukraine, National Science Center Kharkov Institute of Physics and Technology (Ukraine); Lysoivan, A. I., E-mail: a.lyssoivan@fz-juelich.de [Royal Military Academy, EURATOM-Belgian State Association, Laboratory for Plasma Physics (Belgium); Korovin, V. B. [National Academy of Sciences of Ukraine, National Science Center Kharkov Institute of Physics and Technology (Ukraine)

    2013-11-15

    A self-consistent model of radio-frequency (RF) plasma generation in stellarators in the ion cyclotron frequency range is described. The model includes equations for the particle and energy balance and boundary conditions for Maxwell’s equations. The equation of charged particle balance takes into account the influx of particles due to ionization and their loss via diffusion and convection. The equation of electron energy balance takes into account the RF heating power source, as well as energy losses due to the excitation and electron-impact ionization of gas atoms, energy exchange via Coulomb collisions, and plasma heat conduction. The deposited RF power is calculated by solving the boundary problem for Maxwell’s equations. When describing the dissipation of the energy of the RF field, collisional absorption and Landau damping are taken into account. At each time step, Maxwell’s equations are solved for the current profiles of the plasma density and plasma temperature. The calculations are performed for a cylindrical plasma. The plasma is assumed to be axisymmetric and homogeneous along the plasma column. The system of balance equations is solved using the Crank-Nicholson scheme. Maxwell’s equations are solved in a one-dimensional approximation by using the Fourier transformation along the azimuthal and longitudinal coordinates. Results of simulations of RF plasma generation in the Uragan-2M stellarator by using a frame antenna operating at frequencies lower than the ion cyclotron frequency are presented. The calculations show that the slow wave generated by the antenna is efficiently absorbed at the periphery of the plasma column, due to which only a small fraction of the input power reaches the confinement region. As a result, the temperature on the axis of the plasma column remains low, whereas at the periphery it is substantially higher. This leads to strong absorption of the RF field at the periphery via the Landau mechanism.

  3. Catastrophe in plasma focus evolution

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1984-07-01

    A theory of generating strong electric field in a dense plasma column in plasma focus is established by applying the formula for the electron thermal conductivity in destroyed magnetic surfaces like those in tokamaks. The origin of the electric field may be from abrupt rise of plasma resistivity when the irregularity of magnetic field is weak. However, the electric field can be from the inductive origin in case the irregularity attains a certain level. Both origin should be mixed up depending on the magnitude of the irregularity. (author)

  4. Erosion and migration of tungsten employed at the central column heat shield of ASDEX Upgrade

    International Nuclear Information System (INIS)

    Krieger, K.; Gong, X.; Balden, M.; Hildebrandt, D.; Maier, H.; Rohde, V.; Roth, J.; Schneider, W.

    2002-01-01

    In ASDEX Upgrade, tungsten was employed as plasma facing material at the central column heat shield in the plasma main chamber. The campaign averaged tungsten erosion flux was determined by measuring the difference of the W-layer thickness before and after the experimental campaign using ion beam analysis methods. The observed lateral variation and the total amount of eroded tungsten are attributed to erosion by impact of ions from the scrape-off layer plasma. Migration and redeposition of eroded tungsten were investigated by quantitative analysis of deposited tungsten on collector probes and wall samples. The obtained results, as well as the spectroscopically observed low tungsten plasma penetration probability, indicate that a major fraction of the eroded tungsten migrates predominantly through direct transport channels in the outer plasma scrape-off layer without entering the confined plasma

  5. A Parallel Boltzmann Simulation for Multi-grid Inertial Electrostatic Confinement Fusion

    Data.gov (United States)

    National Aeronautics and Space Administration — Inertial electrostatic confinement (IEC) is a means of confining a non-neutral, non-Maxwellian plasma with an electric field, with the goal of creating fusion...

  6. Plasma-Column Equilibrium in Tokamak-5; L'Equilibre d'une Colonne de Plasma dans l'Installation Tokamak-5; Issledovanie ravnovesiya plazmennogo shnura na ustanovke Tokamak-5; El Equilibrio de una Columna de Plasma en la Instalacion 'Tokamak-5'

    Energy Technology Data Exchange (ETDEWEB)

    Muhovatov, V. S. [Institut Atomnoj Ehnergii, Im. I.V. Kurchatova, Moskva, SSSR (Russian Federation)

    1966-04-15

    This paper, which is a continuation of work done by Grigorovich and Mukhovatov, is devoted to an investigation of the conditions of equilibrium of the plasma column in Tokamak-5. This equipment has the following parameters: large radius of the copper casing R = 62. 5 cm, small radius b = 25 cm, small radius of the liner = 20 cm, radius of the opening in the diaphragm = 15 cm (the centre of the opening in the diaphragm and the centre of the cross-section of the casing coincide), intensity of the longitudinal magnetic field B{sub 0} = 6 to 12 kOe and current in the plasma J = 15 to 20 kA, The tests were carried out at an initial hydrogen pressure of (1.8 to 5.0) x 10{sup -4} Torr. Between the casing and the liner were placed conductors, used to set up within the chamber a transverse magnetic field B{sub z} varying synchronously with the discharge current. Grigorovich and Mukhovatov had demonstrated qualitative agreement of experimental results with the hypothesis that the column is maintained in equilibrium by the copper casing, and had shown that the average electrical conductivity of the plasma over the cross-section of the column reaches its maximum if by means of the transverse field B{sub z} the column is arranged concentrically with the opening in the diaphragm. The present paper shows that in most discharge regimes there is good quantitative agreement between the experimental data and the theory of column equilibrium within the conducting casing. However, in a number of discharge regimes (with low initial gas pressures and high values of displacement {Delta}{sub B} = b{sup 2}B{sub z}c/2J directed towards the inner wall of the torus) there is a certain discrepancy between theory and experiment. An attempt was made to assess to what extent the process of cutting off drift current by the conducting diaphragm contributes to maintaining equilibrium of the column in Tokamak. For this purpose the diaphragm was cut into six segments isolated from each other. During a

  7. Plasma Channel Lenses and Plasma Tornadoes for Optical Beam Focusing and Transport

    Science.gov (United States)

    Hubbard, R. F.; Kaganovich, D.; Johnson, L. A.; Gordon, D. F.; Penano, J. R.; Hafizi, B.; Helle, M. H.; Mamonau, A. A.

    2017-10-01

    Shaped plasmas offer the possibility of manipulating laser pulses at intensities far above the damage limits for conventional optics. An example is the plasma channel, which is a cylindrical plasma column with an on-axis density minimum. Long plasma channels have been widely used to guide intense laser pulses, particularly in laser wakefield accelerators. A new concept, the ``plasma tornado'', offers the possibility of creating long plasma channels with no nearby structures and at densities lower than can be achieved by capillary discharges. A short plasma channel can focus a laser pulse in much the same manner as a conventional lens or off-axis parabola. When placed in front of the focal point of an intense laser pulse, a plasma channel lens (PCL) can reduce the effective f-number of conventional focusing optics. When placed beyond the focal point, it can act as a collimator. We will present experimental and modeling results for a new plasma tornado design, review experimental methods for generating short PCLs, and discuss potential applications. Supported by the Naval Research Laboratory Base Program.

  8. Gabor lens focusing of a negative ion beam

    International Nuclear Information System (INIS)

    Palkovic, J.A.; Mills, F.E.; Schmidt, C.; Young, D.E.

    1989-05-01

    Gabor or plasma lenses have previously been used to focus intense beams of positive ions at energies from 10 keV to 5 MeV. It is the large electrostatic field of the non-neutral plasma in the Gabor lens which is responsible for the focusing. Focusing an ion beam with a given sign of charge in a Gabor lens requires a non-neutral plasma with the opposite sign of charge as the beam. A Gabor lens constructed at Fermilab has been used to focus a 30 keV proton beam with good optical quality. We discuss studies of the action of a Gabor lens on a beam of negative ions. A Gabor lens has been considered for matching an H/sup /minus// beam into an RFQ in the redesign of the low energy section of the Fermilab linac. 9 refs., 3 figs., 1 tab

  9. Fabrication of a novel hemin-based monolithic column and its application in separation of protein from complex bio-matrix.

    Science.gov (United States)

    Jiang, Xiaoya; Zhang, Doudou; Li, Xueying; Wang, Xixi; Bai, Ligai; Liu, Haiyan; Yan, Hongyuan

    2017-05-10

    A novel polymer-based monolithic column was prepared via redox initiation system within the confines of a stainless steel column with 4.6mm i.d. In the processes, hemin and lauryl methacrylate were used as co-monomers; ethylene dimethacrylate as crosslinking agent; n-butyl alcohol, ethanediol, and N, N-dimethylformamide as tri-porogens; benzoyl peroxide and N, N-dimethyl aniline as redox initiation system. The resulting polymer-based monolithic columns were characterized by scanning electron microscopy, nitrogen adsorption-desorption instrument, and mercury intrusion porosimeter, respectively. The results illustrated that the improved monolith had relative uniform porous structure, good permeability, and low back pressure. Aromatic compounds were used to test the chromatographic behavior of the monolith, resulting in highest column efficiency of 19 880 plates per meter with reversed-phase mechanism. Furthermore, the homemade monolith was used as the stationary phase of high performance liquid chromatography to separate proteins from complex bio-matrix, including human plasma, egg white, and snailase. The results showed that the monolithic column occupied good separation ability with these complex bio-samples. Excellent specific character of the homemade hemin-based monolith was that it could simultaneously remove high-abundance proteins (including human serum albumin, immunoglobulin G, and human fibrinogen) from human plasma and separate other proteins to different fractions. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Computer simulation of plasma behavior in open-ended linear theta machines. Scientific report 81-5

    Energy Technology Data Exchange (ETDEWEB)

    Stover, E. K.

    1981-04-01

    Zero-dimensional and one-dimensional fluid plasma computer models have been developed to study the behavior of linear theta pinch plasmas. Computer simulation results generated from these codes are compared with data obtained from two theta pinch experiments so that significant machine plasma behavior can be identified. The experiments examined are a collisional experiment, T/sub i/ approx. 50 eV, n/sub e/ approx. 10/sup 17/ cm/sup -3/, where the plasma mean-free-path was significantly less than the plasma column length, and a hot ion species experiment, T/sub i/ approx. 3 keV, n/sub e/ approx. 10/sup 16/ cm/sup -3/, where the ion mean-free-path was on the order of the plasma column length.

  11. Internal modes in high-temperature plasmas

    International Nuclear Information System (INIS)

    Crew, G.B.

    1983-02-01

    The linear stability of current-carrying toroidal plamsas is examined to determine the possibility of exciting global internal modes. The ideal magnetohydrodynamic (MHD) theory provides a useful framework for the analysis of these modes, which involve a kinking of the central portion of the plasma column. Non-ideal effects can also be important, and these are treated for high-temperature regimes where the plasma is collisionless

  12. Quasi-periodic oscillations from post-shock accretion column of polars

    Science.gov (United States)

    Bera, Prasanta; Bhattacharya, Dipankar

    2018-02-01

    A set of strongly magnetized accreting white dwarfs (polars) shows quasi-periodic oscillations (QPOs) with frequency about a Hz in their optical luminosity. These Hz-frequency QPOs are thought to be generated by intensity variations of the emitted radiation originating at the post-shock accretion column. Thermal instability in the post-shock region, triggered by efficient cooling process at the base, is believed to be the primary reason behind the temporal variability. Here, we study the structure and the dynamical properties of the post-shock accretion column including the effects of bremsstrahlung and cyclotron radiation. We find that the presence of significant cyclotron emission in optical band reduces the overall variability of the post-shock region. In the case of a larger post-shock region above the stellar surface, the effects of stratification due to stellar gravity become important. An accretion column, influenced by the strong gravity, has a smaller variability as the strength of the thermal instability at the base of the column is reduced. On the other hand, the cool, dense plasma, accumulated just above the stellar surface, may enhance the post-shock variability due to the propagation of magnetic perturbations. These characteristics of the post-shock region are consistent with the observed properties of V834 Cen and in general with cataclysmic variable sources that exhibit QPO frequency of about a Hz.

  13. Turbulent transport in low-beta plasmas

    DEFF Research Database (Denmark)

    Nielsen, A.H.; Pécseli, H.L.; Juul Rasmussen, J.

    1996-01-01

    Low-frequency electrostatic fluctuations are studied experimentally in a low-P plasma, with particular attention to their importance for the anomalous plasma transport across magnetic field lines. The presence of large coherent structures in a turbulent background at the edge of the plasma column...... is demonstrated by a statistical analysis. The importance of these structures for the turbulent transport is investigated. The study is extended by a multichannel conditional analysis to illustrate detailed properties and parameter dependences of the turbulent transport. (C) 1996 American Institute of Physics....

  14. Mechanized sephadex LH-20 multiple column chromatography as a prerequisite to automated multi-steroid radioimmunoassays

    International Nuclear Information System (INIS)

    Sippell, W.G.; Bidlingmaier, F.; Knorr, D.

    1977-01-01

    In order to establish a procedure for the simultaneous determination of all major corticosteroid hormones and their immediate biological precursors in the same plasma sample, two different mechanized methods for the simultaneous isolation of aldosterone (A), corticosterone (B), 11-deoxycorticosterone (DOC), progesterone (P), 17-hydroxyprogesterone (17-OHP), 11-deoxycorticol (S), cortisol (F), and cortisone (E) from the methylene chloride extracts of 0.1 to 2.0 ml plasma samples have been developed. In both methods, eluate fractions of each of the isolated steroids are automatically pooled and collected from all parallel columns by one programmable linear fraction collector. Due to the high reproducibility of the elution patterns both between different parallel columns and between 30 to 40 consecutive elutions, mean recoveries of tritiated steroids including extraction are 60 to 84% after a single elution and still over 50% after an additional chromatography on 40cm LH-20 colums, with coefficients of variation below 15%. Thus, the eight steroids can be completely isolated from each of ten plasma extracts within 3 to 4 hours, yielding 80 samples readily prepared for subsequent quantitation by radioimmunoassay. (orig./AJ) [de

  15. Essential Characteristics of Plasma Antennas Filled with He-Ar Penning Gases

    International Nuclear Information System (INIS)

    Sun Naifeng; Li Wenzhong; Wang Shiqing; Li Jian; Ci Jiaxiang

    2012-01-01

    Based on the essential theory of Penning gases, the discharge characteristics of He-Ar Penning gases in insulating tubes were analyzed qualitatively. The relation between the effective length of an antenna column filled with He-Ar Penning gases and the applied radio frequency (RF) power was investigated both theoretically and experimentally. The distribution of the plasma density along the antenna column in different conditions was studied. The receiving characteristics of local frequency modulated (FM) electromagnetic waves by the plasma antenna filled with He-Ar Penning gases were compared with those by an aluminum antenna with the same dimensions. Results show that it is feasible to take plasma antennas filled with He-Ar Penning gases as receiving antennas.

  16. FPGA based Fuzzy Logic Controller for plasma position control in ADITYA Tokamak

    International Nuclear Information System (INIS)

    Suratia, Pooja; Patel, Jigneshkumar; Rajpal, Rachana; Kotia, Sorum; Govindarajan, J.

    2012-01-01

    Highlights: ► Evaluation and comparison of the working performance of FLC is done with that of PID Controller. ► FLC is designed using MATLAB Fuzzy Logic Toolbox, and validated on ADITYA RZIP model. ► FLC was implemented on a FPGA. The close-loop testing is done by interfacing FPGA to MATLAB/Simulink. ► Developed FLC controller is able to maintain the plasma column within required range of ±0.05 m and was found to give robust control against various disturbances and faster and smoother response compared to PID Controller. - Abstract: Tokamaks are the most promising devices for obtaining nuclear fusion energy from high-temperature, ionized gas termed as Plasma. The successful operation of tokamak depends on its ability to confine plasma at the geometric center of vacuum vessel with sufficient stability. The quality of plasma discharge in ADITYA Tokamak is strongly related to the radial position of the plasma column in the vacuum vessel. If the plasma column approaches too near to the wall of vacuum vessel, it leads to minor or complete disruption of plasma. Hence the control of plasma position throughout the entire plasma discharge duration is a fundamental requirement. This paper describes Fuzzy Logic Controller (FLC) which is designed for radial plasma position control. This controller is tested and evaluated on the ADITYA RZIP control model. The performance of this FLC was compared with that of Proportional–Integral–Derivative (PID) Controller and the response was found to be faster and smoother. FLC was implemented on a Field Programmable Gate Array (FPGA) chip with the use of a Very High-Speed Integrated-Circuits Hardware Description-Language (VHDL).

  17. Pattern formation and filamentation in low temperature, magnetized plasmas - a numerical approach

    Science.gov (United States)

    Menati, Mohamad; Konopka, Uwe; Thomas, Edward

    2017-10-01

    In low-temperature discharges under the influence of high magnetic field, pattern and filament formation in the plasma has been reported by different groups. The phenomena present themselves as bright plasma columns (filaments) oriented parallel to the magnetic field lines at high magnetic field regime. The plasma structure can filament into different shapes from single columns to spiral and bright rings when viewed from the top. In spite of the extensive experimental observations, the observed effects lack a detailed theoretical and numerical description. In an attempt to numerically explain the plasma filamentation, we present a simplified model for the plasma discharge and power deposition into the plasma. Based on the model, 2-D and 3-D codes are being developed that solve Poisson's equation along with the fluid equations to obtain a self-consistent description of the plasma. The model and preliminary results applied to the specific plasma conditions will be presented. This work was supported by the US Dept. of Energy and NSF, DE-SC0016330, PHY-1613087.

  18. Preparation of Affinity Column Based on Zr{sup 4+} Ion for Phosphoproteins Isolation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seon Mi; Bae, In Ae; Park, Jung Hyen; Kim, Tae Dong; Choi, Seong Ho [Hannam University, Daejeon (Korea, Republic of)

    2009-06-15

    This paper has described about preparation of Zr{sup 4+} affinity column based on the poly(styreneco- glycidyl methacrylate) prepared by emulsion polymerization of styrene and glycidyl methacrylate in order to isolate phosphopeptide. The Zr{sup 4+} ions were introduced after the phophonation of an epoxy group on polymeric microspheres. The successful preparation of Zr{sup 4+}-immobilized polymeric microsphere stationary phase was confirmed through Fourier transform infrared spectra, optical microscopy, scanning electron microscopy, X-ray photoelectron spectra and inductively coupled plasma-atomic emission spectrometer. The separation efficiency for Zr{sup 4+} affinity column prepared by slurry packing was tested to phosphonated casein and dephosphonated casein. The resolution time (min) of the phosphonated casein was higher than that of dephosphated casein for Zr{sup 4+} affinity polymeric microsphere by liquid chromatography. This Zr{sup 4+} affinity column can be used for isolation of phosphonated casein from casein using liquid chromatography.

  19. Numerical study on xenon positive column discharges of mercury-free lamp

    International Nuclear Information System (INIS)

    Ouyang, Jiting; He, Feng; Miao, Jinsong; Wang, Jianqi; Hu, Wenbo

    2007-01-01

    In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells

  20. Experiments on screw-pinch plasmas with elongated cross section

    International Nuclear Information System (INIS)

    Lassing, H.W.

    1989-01-01

    In this thesis experiments are described carried out with SPICA II, a toroidal screw-pinch plasma device. this device is the last one in a series of plasma machines of the toroidal screw-pinch differing from its predecessor in its race-track shaped section. In devices of the type toroidal screw-pinch stable confinement is possible of plasmas with larger β values than in a tokamak discharge. In a pinch the plasma is screwed up, during the formation, in such a way that in a relatively small volume a plasma is formated with a high pressure. During the screwing up the plasma is heated by shock heating as well as adiabatic compression. With the modified snowplow model the density and temperature after the formation can be calculated, starting from the initial conditions. When all ions arrive into the plasma column, the density in the column is determined by the volume compression. First purpose of the experiments was to find a stable discharge. Subsequently discharges have been made with a high as possible β in order to investigate at which maximum β it is possible to confine screw-pinch plasmas stably. When these had been found, the nature and importance could be investigated of the processes following which the screw-pinch plasma looses its energy. (author), 75 res.; 95 figs.; 8 tabs

  1. Medium fidelity modelling of loads in wind farms under non-neutral ABL stability conditions – a full-scale validation study

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Larsen, Torben J.; Chougule, A.

    2017-01-01

    The aim of the present paper is to demonstrate the capability of medium fidelity modelling of wind turbine component fatigue loading, when the wind turbines are subjected to wake affected non-stationary flow fields under non-neutral atmospheric stability conditions. To accomplish this we combine......) in description of both large- and small scale atmospheric boundary layer turbulence is facilitated by a generalization of the classical Mann spectral tensor, which consistently includes buoyancy effects. With non-stationary wind turbine inflow fields modelled as described above, fatigue loads are obtained using...... the state-of-the art aeroelastic model HAWC2. The Lillgrund offshore wind farm (WF) constitute an interesting case study for wind farm model validation, because the WT interspacing is small, which in turn means that wake effects are significant. A huge data set, comprising 5 years of blade and tower load...

  2. Theory of a wall sheath in a gas-discharge plasma

    International Nuclear Information System (INIS)

    Dvinin, S.A.; Dovzhenko, V.A.; Kuzovnikov, A.A.

    1999-01-01

    An integro-differential equation is proposed that generalizes the plasma-sheath (Langmuir-Tonks) equation to include charge exchange between ions and neutrals in a discharge plasma and makes it possible to correctly analyze how the discharge evolves from the regime of collisionless ion motion to the diffusive regime in pure gases with allowance for the space charge in the sheath at the plasma boundary. The integro-differential equation is solved numerically, and the ionization rate is calculated as a function of the ratio between the ion mean free path and the characteristic discharge dimension. The ion energy distribution function in the positive column of a discharge plasma is computed. The parameter range in which the positive column can exist is examined, and the limits of applicability of different discharge models are analyzed depending on the relations between the ion mean free path, Debye length, and discharge dimension

  3. Inter-grain coupling and grain charge in dusty plasma Coulomb crystals

    International Nuclear Information System (INIS)

    Smith, M. A.; Goodrich, J.; Mohideen, U.; Rahman, H. U.; Rosenberg, M.; Mendis, D. A.

    1998-01-01

    We have studied the lattice structure and grain charge of dusty plasma Coulomb crystals formed in rectangular conductive grooves as a function of plasma temperature and density. The crystal appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. A simple phenomenological model wherein the inter-grain spacing results from an attractive electric field induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal

  4. Control of plasma layer in a fusion reactor correlated to DC motor control using PSO-ANFIS

    International Nuclear Information System (INIS)

    Mahapatra, Sakuntala; Daniel, Raju; Dey, Deep Narayan

    2013-01-01

    Plasma position and shape control is very crucial for the overall performance of the fusion reactor such as Tokamak. The quality of the discharge in the Saskatchewan TORus-Modified (STOR-M) tokamak is strongly related to the position of the plasma column within the discharge vessel. If the plasma column approaches too near the wall, then either minor or complete disruption occurs. Consequently it is necessary to be able to control dynamically the position of the plasma column throughout the entire discharge. Now a day's most fusion reactor employs the traditional PID controller for the confinement of plasma layer. Fuzzy logic is used for the control of Plasma layer. In this paper we have used the hybrid of PSO-ANFIS technique to control the speed of a DC motor. We have used two input parameters like speed, torque and output is firing angle. In our work first order Sugeno fuzzy model is taken with three rules and the parameters of Gaussian membership function is controlled by the PSO technique. PSO-ANFIS speed controller obtains better dynamic behavior and superior performance of the DC motor speed control. Similar approach can be correlated to the control of plasma layer. For the plasma control two inputs can be taken as plasma position ΔH and the plasma current and the single output, the control decision u(t). (author)

  5. Collaborative Research: Experimental and Theoretical Study of the Plasma Physics of Antihydrogen Generation and Trapping

    Energy Technology Data Exchange (ETDEWEB)

    Robicheaux, Francis

    2013-03-29

    Ever since Dirac predicted the existence of antimatter in 1928, it has excited our collective imagination. Seventy-four years later, two collaborations at CERN, ATHENA and ATRAP, created the first slow antihydrogen. This was a stunning achievement, but the most important antimatter experiments require trapped, not just slow, antihydrogen. The velocity, magnetic moment, and internal energy and state of the antihydrogen depend strongly on how it is formed. To trap antihydrogen, physicists face two broad challenges: (1) Understanding the behavior of the positron and antiprotons plasmas from which the antihydrogen is synthesized; and (2) Understanding the atomic processes by which positrons and antiprotons recombine. Recombination lies on the boundary between atomic and plasma physics, and cannot be studied properly without employing tools from both fields. The proposed collaborative research campaign will address both of these challenges. The collaboration members have unique experience in the relevant fields of experimental and theoretical non-neutral plasma physics, numerical modeling, nonlinear dynamics and atomic physics. This expertise is not found elsewhere amongst antihydrogen researchers. The collaboration members have strong ties already, and seek to formalize them with this proposal. Three of the four PIs are members of the ALPHA collaboration, an international collaboration formed by most of the principal members of the ATHENA collaboration.

  6. Wireless communication capability of a reconfigurable plasma antenna

    International Nuclear Information System (INIS)

    Kumar, Rajneesh; Bora, Dhiraj

    2011-01-01

    A 30 cm long plasma column is excited by a surface wave, which acts as a plasma antenna. Using plasma properties (pattern formation/striations in plasmas) single plasma antenna can be transformed into array, helical, and spiral plasma antenna. Experiments are carried out to study the power patterns, directivity, and half power beam width of such different plasma antennas. Moreover, field properties of plasma and copper antenna are studied. Further, wireless communication and jamming capability of plasma antenna are tested. Findings of this study suggest that directivity and communication range can be increased by converting single plasma antenna in to array/helical/spiral plasma antenna. Field frequencies of plasma antenna determine the communication and jamming of radio frequency waves. Therefore, this study invokes applications of pattern formation or striations of plasmas in plasma antenna technology.

  7. Negative edge plasma currents in the SINP tokamak

    Indian Academy of Sciences (India)

    RAE is the maximum runaway energy emitted during a burst period of tdur. HXR. There being no plasma control feedback system in the SINP tokamak, the dynamics of the plasma equilibrium is time-dependent and the column shift is now made by the discharge dynamics itself. We measured DRAE for the two discharges ...

  8. Plasma production for the 50 MeV plasma lens experiment at LBL

    International Nuclear Information System (INIS)

    Leemans, W.; van der Geer, B.; de Loos, M.; Conde, M.; Govil, R.; Chattopadhyay, S.

    1994-06-01

    The Center for Beam Physics at LBL has constructed a Beam Test Facility (BTF) housing a 50 MeV electron beam transport line, which uses the linac injector from the Advanced Light Source, and a terawatt Ti:Al 2 O 3 laser system. The linac operates at 50 MeV and generates 15 ps long electron bunches containing a charge of up to 2 nC. The measured unnormalized beam emittance is 0.33 mm-mrad. These parameters allow for a comprehensive study of focusing of relativistic electron beams with plasma columns, in both the overdense and underdense regime (adiabatic and tapered lenses). A study of adiabatic and/or tapered lenses requires careful control of plasma density and scale lengths of the plasma. We present experimental results on the production of plasmas through resonant two-photon ionization, with parameters relevant to an upcoming plasma lens experiment

  9. Column-Oriented Database Systems (Tutorial)

    NARCIS (Netherlands)

    D. Abadi; P.A. Boncz (Peter); S. Harizopoulos

    2009-01-01

    textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as

  10. Ignition phase and steady-state structures of a non-thermal air plasma

    CERN Document Server

    Lu Xin Pei

    2003-01-01

    An AC-driven, non-thermal, atmospheric pressure air plasma is generated within the gap separating a disc-shaped metal electrode and a water electrode. The ignition phase and the steady-state are studied by a high-speed CCD camera. It is found that the plasma always initiates at the surface of the water electrode. The plasma exhibits different structures depending on the polarity of the water electrode: when the water electrode plays the role of cathode, a relatively wide but visibly dim plasma column is generated. At the maximum driving voltage, the gas temperature is between 800 and 900 K, and the peak current is 67 mA; when the water electrode is anode, the plasma column narrows but increases its light emission. The gas temperature in this case is measured to be in the 1400-1500 K range, and the peak current is 81 mA.

  11. Family of columns isospectral to gravity-loaded columns with tip force: A discrete approach

    Science.gov (United States)

    Ramachandran, Nirmal; Ganguli, Ranjan

    2018-06-01

    A discrete model is introduced to analyze transverse vibration of straight, clamped-free (CF) columns of variable cross-sectional geometry under the influence of gravity and a constant axial force at the tip. The discrete model is used to determine critical combinations of loading parameters - a gravity parameter and a tip force parameter - that cause onset of dynamic instability in the CF column. A methodology, based on matrix-factorization, is described to transform the discrete model into a family of models corresponding to weightless and unloaded clamped-free (WUCF) columns, each with a transverse vibration spectrum isospectral to the original model. Characteristics of models in this isospectral family are dependent on three transformation parameters. A procedure is discussed to convert the isospectral discrete model description into geometric description of realistic columns i.e. from the discrete model, we construct isospectral WUCF columns with rectangular cross-sections varying in width and depth. As part of numerical studies to demonstrate efficacy of techniques presented, frequency parameters of a uniform column and three types of tapered CF columns under different combinations of loading parameters are obtained from the discrete model. Critical combinations of these parameters for a typical tapered column are derived. These results match with published results. Example CF columns, under arbitrarily-chosen combinations of loading parameters are considered and for each combination, isospectral WUCF columns are constructed. Role of transformation parameters in determining characteristics of isospectral columns is discussed and optimum values are deduced. Natural frequencies of these WUCF columns computed using Finite Element Method (FEM) match well with those of the given gravity-loaded CF column with tip force, hence confirming isospectrality.

  12. MiniCNT - A Tabletop Stellarator

    Science.gov (United States)

    Dugan, Chris; Pedersen, Thomas; Berkery, John

    2006-10-01

    MiniCNT is a scaled down version of the Columbia Non-Neutral Torus, a stellarator built to study confinement of non-neutral plasmas on magnetic surfaces. MiniCNT is a glass vacuum chamber capable of holding pressures six orders of magnitude below atmospheric pressure. Unlike CNT, in which plasmas are invisible, MiniCNT allows some collisions with neutrals, causing it to glow. Using two twelve-volt car batteries to power four magnetic coils, MiniCNT generates a 0.02 Tesla magnetic field. While CNT, being larger, is obviously more accurate, there are multiple benefits in MiniCNT. First, it is more flexible and can be adjusted to fit many scenarios easily. The car batteries can be switched for other power sources, the coils can be realigned, and the chamber can be pumped to various pressures of various gases. Also, it is visually accessible; while CNT has glass viewing ports and its plasma is dark, MiniCNT is made of glass and its plasma glows, allowing visualization of the magnetic surfaces.

  13. Distillation Column Flooding Predictor

    Energy Technology Data Exchange (ETDEWEB)

    George E. Dzyacky

    2010-11-23

    The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillation columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid

  14. Investigation of stability and x-ray spectrum in gas-puff z-pinch plasmas diriven by inductive energy storage pulsed power generator with a plasma opening switch

    International Nuclear Information System (INIS)

    Murayama, K.; Fukudome, I.; Teramoto, Y.; Katsuki, S.; Akiyama, H.

    2002-01-01

    Gas-puff z-pinch plasmas are driven by an inductive voltage adder - inductive energy storage pulsed power generator ''ASO-X''. ASO-X has the performance of the maximum output voltage and current are 180 kV and 400 kA respectively and can provide a fast rise time current with operating POS. The stability of the plasma column, spectrum radiated from z-pinch plasmas and the spatial distribution of hot spots are investigated in the case with and without operating POS. By driving ASO-X with operating POS the kink instability is restrained and the stability of plasma column is improved about three times in regard to the average dispersion. Furthermore the duration of soft x-ray radiation is increased and the spatial distribution of hot spots is 50% improved with regard to kurtosis of the intensity profile of pinhole photographs compared to those without operating POS. (author)

  15. Annular pulse column development studies

    International Nuclear Information System (INIS)

    Benedict, G.E.

    1980-01-01

    The capacity of critically safe cylindrical pulse columns limits the size of nuclear fuel solvent extraction plants because of the limited cross-sectional area of plutonium, U-235, or U-233 processing columns. Thus, there is a need to increase the cross-sectional area of these columns. This can be accomplished through the use of a column having an annular cross section. The preliminary testing of a pilot-plant-scale annular column has been completed and is reported herein. The column is made from 152.4-mm (6-in.) glass pipe sections with an 89-mm (3.5-in.) o.d. internal tube, giving an annular width of 32-mm (1.25-in.). Louver plates are used to swirl the column contents to prevent channeling of the phases. The data from this testing indicate that this approach can successfully provide larger-cross-section critically safe pulse columns. While the capacity is only 70% of that of a cylindrical column of similar cross section, the efficiency is almost identical to that of a cylindrical column. No evidence was seen of any non-uniform pulsing action from one side of the column to the other

  16. Analysis of cytokine profile and growth factors in platelet-rich plasma obtained by open systems and commercial columns.

    Science.gov (United States)

    Pochini, Alberto de Castro; Antonioli, Eliane; Bucci, Daniella Zanetti; Sardinha, Luiz Roberto; Andreoli, Carlos Vicente; Ferretti, Mario; Ejnisman, Benno; Goldberg, Anna Carla; Cohen, Moisés

    2016-01-01

    To evaluate growth factors and cytokines in samples of platelet-rich plasma obtained by three different centrifugation methods. Peripheral blood of six individuals with no hematological diseases, aged 18 to 68 years, was drawn to obtain platelet-rich plasma, using the open method and commercial columns by Medtronic and Biomet. The products obtained with the different types of centrifugation were submitted to laboratory analysis, including pro-inflammatory cytokines and chemokines by flow cytometry assays, the concentration of fibroblast growth factors-2 (FGF-2) and transforming growth factor-beta1 (TGF-β1). The diverse separation methods generated systematically different profiles regarding number of platelets and leukocytes. The Medtronic system yielded a product with the highest concentration of platelets, and the open method, with the lowest concentration of platelets. The results of cytokine analysis showed that the different types of centrifugation yielded products with high concentrations of interleukin 8, interleukin 1β. The open system resulted in a product with high levels of interleukin 6. Other cytokines and chemokines measured were similar between systems. The product obtained with the open method showed higher levels of TGF-β1 in relation to other systems and low FGF-2 levels. The formed elements, growth factors and cytokines in samples of platelet-rich plasma varied according to the centrifugation technique used. Avaliar fatores de crescimento e citocinas em amostras de plasma rico em plaquetas obtidas por três diferentes métodos de centrifugação. Foi coletado sangue periférico de seis indivíduos, sem doença hematológica, com idades entre 18 e 68 anos, para obtenção de plasma rico em plaquetas, utilizando o método aberto e sistemas comerciais das empresas Medtronic e Biomet. Os produtos obtidos com os diferentes tipos de centrifugação foram submetidos às análises laboratoriais, incluindo citocinas próinflamatórias e quimiocinas

  17. Numerical Simulation of Plasma Antenna with FDTD Method

    International Nuclear Information System (INIS)

    Chao, Liang; Yue-Min, Xu; Zhi-Jiang, Wang

    2008-01-01

    We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconBgurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design

  18. Numerical simulation of plasma antenna with FDTD method

    International Nuclear Information System (INIS)

    Liang Chao; Xu Yuemin; Wang Zhijiang

    2008-01-01

    We adopt cylindrical-coordinate FDTD algorithm to simulate and analyse a 0.4-m-long column configuration plasma antenna. FDTD method is useful for solving electromagnetic problems, especially when wave characteristics and plasma properties are self-consistently related to each other. Focus on the frequency from 75 MHz to 400 MHz, the input impedance and radiation efficiency of plasma antennas are computed. Numerical results show that, different from copper antenna, the characteristics of plasma antenna vary simultaneously with plasma frequency and collision frequency. The property can be used to construct dynamically reconfigurable antenna. The investigation is meaningful and instructional for the optimization of plasma antenna design. (authors)

  19. Column-Oriented Database Systems (Tutorial)

    OpenAIRE

    Abadi, D.; Boncz, Peter; Harizopoulos, S.

    2009-01-01

    textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as opposed to traditional database systems that store entire records (rows) one after the other. Reading a subset of a table’s columns becomes faster, at the potential expense of excessive disk-head s...

  20. Very low pressure plasma sprayed yttria-stabilized zirconia coating using a low-energy plasma gun

    International Nuclear Information System (INIS)

    Zhu, Lin; Zhang, Nannan; Bolot, Rodolphe; Planche, Marie-Pierre; Liao, Hanlin; Coddet, Christian

    2011-01-01

    In the present study, a more economical low-energy plasma source was used to perform a very low pressure plasma-spray (VLPPS) process. The plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Moreover, yttria-stabilized zirconia coating (YSZ) was elaborated by a F100 low-power plasma gun under working pressure of 1 mbar, and the substrate specimens were partially shadowed by a baffle-plate during plasma spraying for obtaining different coating microstructures. Based on the SEM observation, a column-like grain coating was deposited by pure vapor deposition at the shadowed region, whereas, in the unshadowed region, the coating exhibited a binary microstructure which was formed by a mixed deposition of melted particles and evaporated particles. The mechanical properties of the coating were also well under investigation. (orig.)

  1. Study of plasma discharge evolution and edge turbulence with fast visible imaging in the Aditya tokamak

    International Nuclear Information System (INIS)

    Banerjee, Santanu; Manchanda, R.; Chowdhuri, M.B.

    2015-01-01

    Study of discharge evolution through the different phases of a tokamak plasma shot viz., the discharge initiation, current ramp-up, current flat-top and discharge termination, is essential to address many inherent issues of the operation of a Tokamak. Fast visible imaging of the tokamak plasma can provide valuable insight in this regard. Further, edge turbulence is considered to be one of the quintessential areas of tokamak research as the edge plasma is at the immediate vicinity of the plasma core and plays vital role in the core plasma confinement. The edge plasma also bridges the core and the scrape off layer (SOL) of the tokamak and hence has a bearing on the particle and heat flux escaping the plasma column. Two fast visible imaging systems are installed on the Aditya tokamak. One of the system is for imaging the plasma evolution with a wide angle lens covering a major portion of the vacuum vessel. The imaging fiber bundle along with the objective lens is installed inside a radial re-entrant viewport, specially designed for the purpose. Another system is intended for tangential imaging of the plasma column. Formation of the plasma column and its evolution are studied with the fast visible imaging in Aditya. Features of the ECRH and LHCD operations on Aditya will be discussed. 3D filaments can, be seen at the plasma edge all along the discharge and they get amplified in intensity at the plasma termination phase. Statistical analysis of these filaments, which are essentially plasma blobs will be presented. (author)

  2. Inertial electro-magnetostatic plasma neutron sources

    International Nuclear Information System (INIS)

    Barnes, D.C.; Nebel, R.A.; Schauer, M.M.; Pickrel, M.M.

    1997-01-01

    Two types of systems are being studied experimentally as D-T plasma neutron sources. In both concepts, spherical convergence of either electrons or ions or both is used to produce a dense central focus within which D-T fusion reactions produce 14 MeV neutrons. One concept uses nonneutral plasma confinement principles in a Penning type trap. In this approach, combined electrostatic and magnetic fields provide a vacuum potential well within which electrons are confined and focused. A small (6 mm radius) spherical machine has demonstrated a focus of 30 microm radius, with a central density of up to 35 times the Brillouin density limit of a static trap. The resulting electron plasma of up to several 10 13 cm -3 provides a multi-kV electrostatic well for confining thermonuclear ions as a neutron source. The second concept (Inertial Electrostatic Confinement, or IEC) uses a high-transparence grid to form a global well for acceleration and confinement of ions. Such a system has demonstrated steady neutron output of 2 x 10 10 s -1 . The present experiment will scale this to >10 11 s -1 . Advanced designs based on each concept have been developed recently. In these proposed approaches, a uniform-density electron sphere forms an electrostatic well for ions. Ions so trapped may be focused by spherical convergence to produce a dense core. An alternative approach produces large amplitude spherical oscillations of a confined ion cloud by a small, resonant modulation of the background electrons. In both the advanced Penning trap approach and the advanced IEC approach, the electrons are magnetically insulated from a large (up to 100 kV) applied electrostatic field. The physics of these devices is discussed, experimental design details are given, present observations are analyzed theoretically, and the performance of future advanced systems are predicted

  3. Nuclear reactor control column

    International Nuclear Information System (INIS)

    Bachovchin, D.M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest crosssectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor

  4. Improvements in solvent extraction columns

    International Nuclear Information System (INIS)

    Aughwane, K.R.

    1987-01-01

    Solvent extraction columns are used in the reprocessing of irradiated nuclear fuel. For an effective reprocessing operation a solvent extraction column is required which is capable of distributing the feed over most of the column. The patent describes improvements in solvent extractions columns which allows the feed to be distributed over an increased length of column than was previously possible. (U.K.)

  5. RFP plasma experiment at INPE

    International Nuclear Information System (INIS)

    Ueda, M.; Aso, Y.

    1988-01-01

    Plasma experiments in CECI, a small Reversed Field Pinch (RFP) apparatus, are described. Preliminary measurements in this device shown the production of a plasma with peak current of 1.3kA and discharge duration of nearly 80μs, when a toroidal DC field of 100G was used. A loop voltage of 40V was measured and a maximum electron temperature of 3eV was estimated for these discharges. Experimental points in the F-θ diagram for CECI indicate that its plasma is approaching the RFP configuration when the discharge is optimize. The probe data also show that the plasma column expands outward. Numerical results indicate that leakage fields have to be reduced below 5G to form appropriate magnetic surfaces. (author) [pt

  6. Plasma L-ergothioneine measurement by high-performance liquid chromatography and capillary electrophoresis after a pre-column derivatization with 5-iodoacetamidofluorescein (5-IAF) and fluorescence detection.

    Science.gov (United States)

    Sotgia, Salvatore; Pisanu, Elisabetta; Pintus, Gianfranco; Erre, Gian Luca; Pinna, Gerard Aime; Deiana, Luca; Carru, Ciriaco; Zinellu, Angelo

    2013-01-01

    Two sensitive and reproducible capillary electrophoresis and high-performance liquid chromatography-fluorescence procedures were established for quantitative determination of L-egothioneine in plasma. After derivatization of L-ergothioneine with 5-iodoacetamidofluorescein, the separation was carried out by HPLC on an ODS-2 C-18 sperisorb column by using a linear gradient elution and by HPCE on an uncoated fused silica capillary, 50 µm id, and 60 cm length. The methods were validated and found to be linear in the range of 0.3 to 10 µmol/l. The limit of quantification was 0.27 µmol/l for HPCE and 0.15 µmol/l for HPLC. The variations for intra- and inter-assay precision were around 6 RSD%, and the mean recovery accuracy close to 100% (96.11%).

  7. Ion pulse propagation through a previously unfilled electrostatic aperture lens accelerating column

    International Nuclear Information System (INIS)

    Rutkowski, H.L.; Eylon, S.; Keeney, D.S.; Chen, Y.J.; Hewett, D.W.; Barnard, J.

    1993-01-01

    Heavy Ion Fusion experiments require very high current beams with excellent beam quality during a short pulse. Scaled experiments planned at LBL require very short pulses (μsec) compared to what one expects in an HIF driver (20-30 μs). A 1MV acceleration column composed of aperture lenses has been constructed at LBL in order to study the propagation effects on such ion pulses. The column is initially empty of space charge but with the full acceleration potential applied. A short current pulse is then injected into the column with a planar diode open-quotes current valve.close quotes Effects on the pulse propagation due to rise time, pulse duration, and beam size have been studied. Experiments on transported beam current and emittance have been conducted using a carbon arc plasma source (2 double-prime and .5 double-prime diameter) and a 1 double-prime diameter alumino-silicate potassium ion source. Computer simulations using a 2.5D time dependent code are compared with the experimental data

  8. Spatial and Time Dynamics of Non-Linear Vortices in Plasma Lens for High-Current Ion Beam Focusing

    Science.gov (United States)

    Goncharov, Alexei A.; Maslov, Vasyl I.; Onishchenko, Ivan N.; Tretyakov, Vitalij N.

    2002-11-01

    It is known from numerical simulation (see, for example, [1]) and from experiments (see, for example, [2]), that an electron density bunches as discrete vortices are long - living structures in vacuum. However, in laboratory experiments [2] it has been shown that the vortices are changed faster, when they are submersed in electrons, distributed around them. The charged plasma lens intended for a focussing of high-current ion beams, has the same crossed configuration of a radial electrical and longitudinal magnetic field [3], as only electron plasma. In this lens the vortical turbulence is excited [3]. The vortex - bunch and vortex - hole are rotated in the inverse directions in system of their rest. The instability development in initially homogeneous plasma causes that the vortices are excited by pairs. Namely, if the vortex - bunch of electrons is generated, near the vortex - hole of electrons is also generated. It is shown, that in nonuniform plasma the vortices behave is various in time. Namely, the vortex - bunch goes to area of larger electron density, and the vortex - hole goes to area of smaller electron density. The speed of the vortex - hole is less than speed of the vortex - bunch. It is shown, that the electron vortices, generated in the plasma lens, can result in to formation of spiral distribution of electron density. The physical mechanism of coalescence of electron vortices - bunches is proposed. 1.Driscoll C.F. et al. Plasma Phys. Contr. Fus. Res. 3 (1989) 507. 2.Kiwamoto Y. et al. Non-neutral plasma physics. Princeton. 1999. P. 99-105. 3.Goncharov A. et al. Plasma Phys. Rep. 20 (1994) 499.

  9. High-beta plasma effects in a low-pressure helicon plasma

    International Nuclear Information System (INIS)

    Corr, C. S.; Boswell, R. W.

    2007-01-01

    In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900 W and a magnetic field of 30 G a narrow column of bright blue light (due to Ar II radiation) is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber; however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field (B z ) and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is ∼2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed

  10. ( Anogeissus leiocarpus ) timber columns

    African Journals Online (AJOL)

    A procedure for designing axially loaded Ayin (Anogeissus leiocarpus) wood column or strut has been investigated. Instead of the usual categorization of columns into short, intermediate and slender according to the value of slenderness ratio, a continuous column formula representing the three categories was derived.

  11. Binding of HIV-1 gp41-directed neutralizing and non-neutralizing fragment antibody binding domain (Fab and single chain variable fragment (ScFv antibodies to the ectodomain of gp41 in the pre-hairpin and six-helix bundle conformations.

    Directory of Open Access Journals (Sweden)

    John M Louis

    Full Text Available We previously reported a series of antibodies, in fragment antigen binding domain (Fab formats, selected from a human non-immune phage library, directed against the internal trimeric coiled-coil of the N-heptad repeat (N-HR of HIV-1 gp41. Broadly neutralizing antibodies from that series bind to both the fully exposed N-HR trimer, representing the pre-hairpin intermediate state of gp41, and to partially-exposed N-HR helices within the context of the gp41 six-helix bundle. While the affinities of the Fabs for pre-hairpin intermediate mimetics vary by only 2 to 20-fold between neutralizing and non-neutralizing antibodies, differences in inhibition of viral entry exceed three orders of magnitude. Here we compare the binding of neutralizing (8066 and non-neutralizing (8062 antibodies, differing in only four positions within the CDR-H2 binding loop, in Fab and single chain variable fragment (ScFv formats, to several pre-hairpin intermediate and six-helix bundle constructs of gp41. Residues 56 and 58 of the mini-antibodies are shown to be crucial for neutralization activity. There is a large differential (≥ 150-fold in binding affinity between neutralizing and non-neutralizing antibodies to the six-helix bundle of gp41 and binding to the six-helix bundle does not involve displacement of the outer C-terminal helices of the bundle. The binding stoichiometry is one six-helix bundle to one Fab or three ScFvs. We postulate that neutralization by the 8066 antibody is achieved by binding to a continuum of states along the fusion pathway from the pre-hairpin intermediate all the way to the formation of the six-helix bundle, but prior to irreversible fusion between viral and cellular membranes.

  12. Investigation of stability and x-ray spectrum in gas-puff z-pinch plasmas diriven by inductive energy storage pulsed power generator with a plasma opening switch

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, K.; Fukudome, I. [Yatsushiro National College of Technology, Dept. of Mechanical and Electrical Engineering, Yatsushiro, Kumamoto (Japan); Teramoto, Y.; Katsuki, S.; Akiyama, H. [Kumamoto Univ., Dept. of Electrical and Computer Engineering, Kumamoto (Japan)

    2002-06-01

    Gas-puff z-pinch plasmas are driven by an inductive voltage adder - inductive energy storage pulsed power generator ''ASO-X''. ASO-X has the performance of the maximum output voltage and current are 180 kV and 400 kA respectively and can provide a fast rise time current with operating POS. The stability of the plasma column, spectrum radiated from z-pinch plasmas and the spatial distribution of hot spots are investigated in the case with and without operating POS. By driving ASO-X with operating POS the kink instability is restrained and the stability of plasma column is improved about three times in regard to the average dispersion. Furthermore the duration of soft x-ray radiation is increased and the spatial distribution of hot spots is 50% improved with regard to kurtosis of the intensity profile of pinhole photographs compared to those without operating POS. (author)

  13. LIQUID-LIQUID EXTRACTION COLUMNS

    Science.gov (United States)

    Thornton, J.D.

    1957-12-31

    This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.

  14. Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with off-line column preconcentration using 2,6-diacetylpyridine functionalized Amberlite XAD-4

    Energy Technology Data Exchange (ETDEWEB)

    Karadas, Cennet [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Kara, Derya, E-mail: dkara@balikesir.edu.tr [Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir (Turkey); Fisher, Andrew [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom)

    2011-03-18

    An off-line column preconcentration technique using a micro-column of 2,6 diacetylpyridine functionalized Amberlite XAD-4 with inductively coupled plasma mass spectrometry (ICP-MS) as a means of detection has been developed. The aim of the method was to determine rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. Sample solutions (2-10 mL) were passed through the column which was then washed with ultra-pure water to remove residual matrix. The adsorbed cations on the resin were eluted by using 2 mL of 0.1 mol L{sup -1} HNO{sub 3} containing 10 ng mL{sup -1} indium as an internal standard. The eluent was analyzed for the metal concentrations using ICP-MS. Sample pH as well as the sample and eluent flow rates were optimized. The sorption capacity of resin was determined by the batch process, by equilibrating 0.05 g of the resin with solutions of 50 mL of 25 mg L{sup -1} of individual metal ions for 4 h at pH 6.0 at 26 deg. C. The sorption capacities for the resin were found to range between 47.3 {mu}mol g{sup -1} (for Lu) and 136.7 {mu}mol g{sup -1} (for Gd). Limits of detection (3{sigma}), without any preconcentration, ranged from 2 ng L{sup -1} to 10.3 ng L{sup -1} (for Tm and Lu respectively). The proposed method was applied to the determination of REEs in seawater and tap water samples.

  15. Enantioselective determination of 3-n-butylphthalide (NBP) in human plasma by liquid chromatography on a teicoplanin-based chiral column coupled with tandem mass spectrometry.

    Science.gov (United States)

    Diao, Xingxing; Ma, Zhiyu; Lei, Peng; Zhong, Dafang; Zhang, Yifan; Chen, Xiaoyan

    2013-11-15

    A novel and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine the exposure of 3-n-butylphthalide (NBP) enantiomers in human plasma. The NBP enantiomers were extracted from human plasma using methyl tert-butyl ether. The baseline separation of R-(+)-NBP and S-(-)-NBP was achieved within 11.0min using a teicoplanin-based Astec Chirobiotic T column (250mm×4.6mm i.d., 5μm) under isocratic conditions at a flow rate of 0.6mL/min. The selection of the chiral stationary phase and the effect of the mobile phase composition on the resolution of the enantiomers were discussed. The selectivity, linearity, precision, accuracy, matrix effect, recovery, and stability were evaluated under optimized conditions. The LC-MS/MS method using 200μL of human plasma was linear over the concentration range of 5.00-400ng/mL for each enantiomer. The lower limit of quantification (LLOQ) for both enantiomers was 5.00ng/mL. The intra- and inter-assay precision values of the replicated quality control samples were within 8.0% for each enantiomer. The mean accuracy values for the quality control samples were within ±6.1% of the nominal values for R-(+)-NBP and S-(-)-NBP. No chiral inversion was observed during sample storage, preparation, and analysis. The method proved suitable for enantioselective pharmacokinetic studies of NBP after an oral administration of a therapeutic dose of racemic NBP. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Scalability of pre-packed preparative chromatography columns with different diameters and lengths taking into account extra column effects.

    Science.gov (United States)

    Schweiger, Susanne; Jungbauer, Alois

    2018-02-16

    Small pre-packed columns are commonly used to estimate the optimum run parameters for pilot and production scale. The question arises if the experiments obtained with these columns are scalable, because there are substantial changes in extra column volume when going from a very small scale to a benchtop column. In this study we demonstrate the scalability of pre-packed disposable and non-disposable columns of volumes in the range of 0.2-20 ml packed with various media using superficial velocities in the range of 30-500 cm/h. We found that the relative contribution of extra column band broadening to total band broadening was not only high for columns with small diameters, but also for columns with a larger volume due to their wider diameter. The extra column band broadening can be more than 50% for columns with volumes larger than 10 ml. An increase in column diameter leads to high additional extra column band broadening in the filter, frits, and adapters of the columns. We found a linear relationship between intra column band broadening and column length, which increased stepwise with increases in column diameter. This effect was also corroborated by CFD simulation. The intra column band broadening was the same for columns packed with different media. An empirical engineering equation and the data gained from the extra column effects allowed us to predict the intra, extra, and total column band broadening just from column length, diameter, and flow rate. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  17. The effect of plasma density profile on the backscatter of microwaves from a plasma-covered plane conductor

    International Nuclear Information System (INIS)

    Destler, W.W.; Singh, A.; Rodgers, J.

    1993-01-01

    In order to gain further insight into the mechanism of anomalous absorption of microwaves in a pulsed plasma column, the latter was studied using single and double Langmuir probes. Graphs of plasma potential recorded by floating Langmuir probes as a function of time were obtained for a range of pressure of the background gas and at different distances from the plasma-covered plane-conducting plate. From this data, two main components of the plasma have been identified. The first appears earlier, exhibits greater fluctuations and is shorter in duration than the second component. The presence of these two plasma components is consistent with earlier observations obtained from transverse transmission measurements of microwaves through the plasma. Variations in the envelopes of these two components as experimental conditions are changed will be presented. Microwave backscatter measurements under varying conditions of plasma-density profile and ambient gas pressure will also be presented

  18. Characterization of RNA from Exosomes and Other Extracellular Vesicles Isolated by a Novel Spin Column-Based Method

    Science.gov (United States)

    Enderle, Daniel; Spiel, Alexandra; Coticchia, Christine M.; Berghoff, Emily; Mueller, Romy; Schlumpberger, Martin; Sprenger-Haussels, Markus; Shaffer, Jonathan M.; Lader, Eric; Skog, Johan; Noerholm, Mikkel

    2015-01-01

    Exosomes and other extracellular vesicles (commonly referred to as EVs) have generated a lot of attention for their potential applications in both diagnostics and therapeutics. The contents of these vesicles are the subject of intense research, and the relatively recent discovery of RNA inside EVs has raised interest in the biological function of these RNAs as well as their potential as biomarkers for cancer and other diseases. Traditional ultracentrifugation-based protocols to isolate EVs are labor-intensive and subject to significant variability. Various attempts to develop methods with robust, reproducible performance have not yet been completely successful. Here, we report the development and characterization of a spin column-based method for the isolation of total RNA from EVs in serum and plasma. This method isolates highly pure RNA of equal or higher quantity compared to ultracentrifugation, with high specificity for vesicular over non-vesicular RNA. The spin columns have a capacity to handle up to 4 mL sample volume, enabling detection of low-abundance transcripts in serum and plasma. We conclude that the method is an improvement over traditional methods in providing a faster, more standardized way to achieve reliable high quality RNA preparations from EVs in biofluids such as serum and plasma. The first kit utilizing this new method has recently been made available by Qiagen as “exoRNeasy Serum/Plasma Maxi Kit”. PMID:26317354

  19. Magnetic diagnostic plasma position in the TCA/BR tokamak

    International Nuclear Information System (INIS)

    Galvao, R.M.O.; Kuznetsov, Yu.K.; Nascimento, I.C.

    1996-01-01

    The cross-section of the plasma column is TCA/BR has a nearly circular plasma shape. This allows implementation of simplified methods of magnetic diagnostics. Although these methods were in may tokamaks and are well described, their accuracies are not clearly defined because the very simplified theoretical model of plasma equilibrium on which they are based differs from the real conditions in tokamaks like TCA/BR. In this paper we present the methods of plasma position diagnostics in TCA/BR from external magnetic measurements with an error analysis. (author). 4 refs., 3 figs

  20. Chaos control and taming of turbulence in plasma devices

    DEFF Research Database (Denmark)

    Klinger, T.; Schröder, C.; Block, D.

    2001-01-01

    Chaos and turbulence are often considered as troublesome features of plasma devices. In the general framework of nonlinear dynamical systems, a number of strategies have been developed to achieve active control over complex temporal or spatio-temporal behavior. Many of these techniques apply...... to plasma instabilities. In the present paper we discuss recent progress in chaos control and taming of turbulence in three different plasma "model" experiments: (1) Chaotic oscillations in simple plasma diodes, (2) ionization wave turbulence in the positive column of glow discharges, and (3) drift wave...

  1. Two-dimensional positive column structure with dust cloud: Experiment and nonlocal kinetic simulation

    Science.gov (United States)

    Zobnin, A. V.; Usachev, A. D.; Petrov, O. F.; Fortov, V. E.; Thoma, M. H.; Fink, M. A.

    2018-03-01

    The influence of a dust cloud on the structure of the positive column of a direct current gas discharge in a cylindrical glass tube under milligravity conditions has been studied both experimentally and numerically. The discharge was produced in neon at 60 Pa in a glass tube with a diameter of 30 mm at a discharge current 1 mA. Spherical monodisperse melamine formaldehyde dust particles with a diameter of 6.86 μm were injected into the positive column and formed there a uniform dust cloud with a maximum diameter of 14.4 mm. The shape of the cloud and the dust particle number density were measured. The cloud was stationary in the radial direction and slowly drifted in the axial direction. It was found that in the presence of the dust cloud, the intensity of the neon spectral line with a wavelength by 585.25 nm emitted by the discharge plasma increased by 2.3 times and 2 striations appeared on the anode side of the cloud. A numerical simulation of the discharge was performed using the 2D (quasi-3D) nonlocal self-consistent kinetic model of a longitudinally inhomogeneous axially symmetric positive column [Zobnin et al., Phys. Plasmas 21, 113503 (2014)], which was supplemented by a program module performing a self-consistent calculation of dust particle charges, the plasma recombination rate on dust particles, and ion scattering on dust particles. A new approach to the calculation of particle charges and the screening radius in dense dust clouds is proposed. The results of the simulation are presented, compared with experimental data and discussed. It is demonstrated that for the best agreement between simulated and experimental data, it is necessary to take into account the reflection of electrons from the dust particle surface in order to correctly describe the recombination rate in the cloud, its radial stability, and the dust particle charges.

  2. Formation of thermal eddies during rf heating of plasma

    International Nuclear Information System (INIS)

    Motley, R.W.; Hooke, W.M.; Anania, G.

    1979-07-01

    Moderate power (approx.1 kW) excitation of lower hybrid waves in a linear plasma column is found to increase the reflectivity of the phased waveguide exciter and to change the vertical position of the resonance cone. Probing of the plasma near the mouth of the waveguide reveals that the increased reflection results from an undulation in the plasma surface. We present evidence that this surface distortion is driven by thermal eddies associated with asymmetrical electron heating

  3. Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes

    Energy Technology Data Exchange (ETDEWEB)

    Wittig, Georg; Karger, Oliver S.; Knetsch, Alexander [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Xi, Yunfeng; Deng, Aihua; Rosenzweig, James B. [Particle Beam Physics Laboratory, UCLA, Los Angeles, CA 90095 (United States); Bruhwiler, David L. [RadiaSoft LLC, Boulder, CO 80304 (United States); RadiaBeam Technologies LLC (United States); Smith, Jonathan [Tech-X UK Ltd, Daresbury, Cheshire WA4 4FS (United Kingdom); Sheng, Zheng-Ming; Jaroszynski, Dino A.; Manahan, Grace G. [Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Hidding, Bernhard [Institute of Experimental Physics, University of Hamburg, 22761 Hamburg (Germany); Physics Department, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2016-09-01

    We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical “plasma torch” distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement.

  4. Complexes of neutralizing and non-neutralizing affinity matured Fabs with a mimetic of the internal trimeric coiled-coil of HIV-1 gp41.

    Directory of Open Access Journals (Sweden)

    Elena Gustchina

    Full Text Available A series of mini-antibodies (monovalent and bivalent Fabs targeting the conserved internal trimeric coiled-coil of the N-heptad repeat (N-HR of HIV-1 gp41 has been previously constructed and reported. Crystal structures of two closely related monovalent Fabs, one (Fab 8066 broadly neutralizing across a wide panel of HIV-1 subtype B and C viruses, and the other (Fab 8062 non-neutralizing, representing the extremes of this series, were previously solved as complexes with 5-Helix, a gp41 pre-hairpin intermediate mimetic. Binding of these Fabs to covalently stabilized chimeric trimers of N-peptides of HIV-1 gp41 (named (CCIZN363 or 3-H has now been investigated using X-ray crystallography, cryo-electron microscopy, and a variety of biophysical methods. Crystal structures of the complexes between 3-H and Fab 8066 and Fab 8062 were determined at 2.8 and 3.0 Å resolution, respectively. Although the structures of the complexes with the neutralizing Fab 8066 and its non-neutralizing counterpart Fab 8062 were generally similar, small differences between them could be correlated with the biological properties of these antibodies. The conformations of the corresponding CDRs of each antibody in the complexes with 3-H and 5-Helix are very similar. The adaptation to a different target upon complex formation is predominantly achieved by changes in the structure of the trimer of N-HR helices, as well as by adjustment of the orientation of the Fab molecule relative to the N-HR in the complex, via rigid-body movement. The structural data presented here indicate that binding of three Fabs 8062 with high affinity requires more significant changes in the structure of the N-HR trimer compared to binding of Fab 8066. A comparative analysis of the structures of Fabs complexed to different gp41 intermediate mimetics allows further evaluation of biological relevance for generation of neutralizing antibodies, as well as provides novel structural insights into immunogen

  5. On-line Automated Sample Preparation-Capillary Gas Chromatography for the Analysis of Plasma Samples.

    NARCIS (Netherlands)

    Louter, A.J.H.; van der Wagt, R.A.C.A.; Brinkman, U.A.T.

    1995-01-01

    An automated sample preparation module, (the automated sample preparation with extraction columns, ASPEC), was interfaced with a capillary gas chromatograph (GC) by means of an on-column interface. The system was optimised for the determination of the antidepressant trazodone in plasma. The clean-up

  6. Simulation models for computational plasma physics: Concluding report

    International Nuclear Information System (INIS)

    Hewett, D.W.

    1994-01-01

    In this project, the authors enhanced their ability to numerically simulate bounded plasmas that are dominated by low-frequency electric and magnetic fields. They moved towards this goal in several ways; they are now in a position to play significant roles in the modeling of low-frequency electromagnetic plasmas in several new industrial applications. They have significantly increased their facility with the computational methods invented to solve the low frequency limit of Maxwell's equations (DiPeso, Hewett, accepted, J. Comp. Phys., 1993). This low frequency model is called the Streamlined Darwin Field model (SDF, Hewett, Larson, and Doss, J. Comp. Phys., 1992) has now been implemented in a fully non-neutral SDF code BEAGLE (Larson, Ph.D. dissertation, 1993) and has further extended to the quasi-neutral limit (DiPeso, Hewett, Comp. Phys. Comm., 1993). In addition, they have resurrected the quasi-neutral, zero-electron-inertia model (ZMR) and began the task of incorporating internal boundary conditions into this model that have the flexibility of those in GYMNOS, a magnetostatic code now used in ion source work (Hewett, Chen, ICF Quarterly Report, July--September, 1993). Finally, near the end of this project, they invented a new type of banded matrix solver that can be implemented on a massively parallel computer -- thus opening the door for the use of all their ADI schemes on these new computer architecture's (Mattor, Williams, Hewett, submitted to Parallel Computing, 1993)

  7. Analysis of plasma behavior and electro-magnetic interaction between plasma and device

    International Nuclear Information System (INIS)

    Kobayashi, Tomofumi

    1980-01-01

    A simulation program for the analysis of plasma behavior and the electromagnetic interaction between plasma and device has been developed. The program consists of a part for the analysis of plasma behavior (plasma system) and a part for the analysis of the electro-magnetic interaction between plasma and devices (circuit system). The parameters which connect the plasma system and the circuit system are the electric resistance of plasma, the internal inductance, and the plasma current. For the plasma system, the simultaneous equations which describe the density distribution of plasma particles, the temperature distribution of electrons and ions, and the space-time variation of current density distribution were derived. The one-dimensional plasma column in γ-direction was considered. The electric resistance and the internal inductance can be deduced. The circuit components are a current transformer, a vertical field coil, a quadrupole field coil, a vacuum chamber and others. An equation which describes plasma position and the shape of cross section is introduced. The plasma position can be known by solving the Mukhavatov's formula of equilibrium. By using this program, the build-up process of plasma current in JT-60 was analysed. It was found that the expansion of plasma sub radius and the control of current distribution by gas injection are the effective methods to obtain high temperature and high density plasma. The eddy current induced in a vacuum vessel shields 40 percent of magnetic field made in the plasma region by a vertical field coil. (Kato, T.)

  8. Optimization and simulation of tandem column supercritical fluid chromatography separations using column back pressure as a unique parameter.

    Science.gov (United States)

    Wang, Chunlei; Tymiak, Adrienne A; Zhang, Yingru

    2014-04-15

    Tandem column supercritical fluid chromatography (SFC) has demonstrated to be a useful technique to resolve complex mixtures by serially coupling two columns of different selectivity. The overall selectivity of a tandem column separation is the retention time weighted average of selectivity from each coupled column. Currently, the method development merely relies on extensive screenings and is often a hit-or-miss process. No attention is paid to independently adjust retention and selectivity contributions from individual columns. In this study, we show how tandem column SFC selectivity can be optimized by changing relative dimensions (length or inner diameter) of the coupled columns. Moreover, we apply column back pressure as a unique parameter for SFC optimization. Continuous tuning of tandem column SFC selectivity is illustrated through column back pressure adjustments of the upstream column, for the first time. In addition, we show how and why changing coupling order of the columns can produce dramatically different separations. Using the empirical mathematical equation derived in our previous study, we also demonstrate a simulation of tandem column separations based on a single retention time measurement on each column. The simulation compares well with experimental results and correctly predicts column order and back pressure effects on the separations. Finally, considerations on instrument and column hardware requirements are discussed.

  9. Time-dependent simulation of plasma and electrodes in high-intensity discharge lamps with different electrode shapes

    CERN Document Server

    Flesch, P

    2003-01-01

    The subject of this paper is the modelling of d.c. and a.c. high-intensity Hg-discharge lamps with differently shaped electrodes. Different arc attachments on the electrodes are studied and insight for the development of new electrodes is gained. The model includes the entire discharge plasma (plasma column, hot plasma spots in front of electrodes, near-electrode non-LTE-plasma) as well as anode and cathode. No subdivision of the discharge space into different regions is necessary (like space charge layer, ionization zone, plasma column). This is achieved by using a differential equation for a non-LTE electrical conductivity which is applicable for local thermal equilibrium (LTE-)regions as well as for non-LTE plasma regions close to the electrodes in a high pressure plasma. Modelling results for a 0.6 MPa mercury discharge considering six different electrode shapes (anode and cathode) are presented and compared with experimental results. The electrodes have different diameters and different electrode tips, s...

  10. Power supplies for plasma column control in COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Havlíček, Josef; Hauptmann, R.; Peroutka, Oldřich; Tadros, Momtaz; Hron, Martin; Janky, Filip; Vondráček, Petr; Cahyna, Pavel; Mikulín, Ondřej; Šesták, David; Junek, Pavel; Pánek, Radomír

    2013-01-01

    Roč. 88, 9-10 (2013), s. 1640-1645 ISSN 0920-3796. [Symposium on Fusion Technology (SOFT-27)/27./. Liège, 24.09.2012-28.09.2012] R&D Projects: GA ČR GAP205/11/2470; GA MŠk 7G10072; GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : tokamak * Power supplies * Feedback control * Vertical displacement * Vertical kicks Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.149, year: 2013 http://www.sciencedirect.com/science/article/pii/S0920379613001543#

  11. Characterization of a Low Intensity Plasma Jet

    International Nuclear Information System (INIS)

    Urruchi, W. I.; Maciel, H.S.; Petraconi, G.; Otani, C.

    1999-01-01

    A source of streaming plasma having charged particles energies in the range of tens of electron volts has been built and characterized. The source is based on a dc glow discharge in a cylindrical tube which is connected to a vacuum chamber through a small orifice. A streaming plasma of conical shape emerging from the orifice is formed when the discharge is run between the cathode located inside the tube and the anode located in the vacuum chamber. The strong constriction of the discharge leads to the formation of a plasma sac, in the orifice region, between the positive column and the plasma beam. Properties of these plasmas were investigated using a movable Langmuir probe and an electrostatic energy analyzer. A mechanism based on the formation of double-layers (DL) between the ''plasma sac'' and the adjacent plasmas is proposed to explain the acceleration of the plasma jet charged particles. (author)

  12. Actinides analysis in emergency situation by on-line coupling between a calix[6]arene-based chromatography column and an Inductively Coupled Plasma-Mass Spectrometer

    International Nuclear Information System (INIS)

    Baghdadi, Sarah

    2015-01-01

    In the event of a nuclear crisis, involving actinides (U, Pu, Am) it is important to have fast analysis methods available in order to identify people that could be contaminated. Usually, they are performed in urine or faeces. Even though, analytical methods used with alpha detection are reliable they are lengthy and tedious to set up. This work consisted in developing an on-line coupling method between a calix[6]arene-based chromatography column and an inductively coupled plasma mass spectrometer (ICP-MS). To do so, a speciation study of actinides in mineralised urine was developed to understand the chemical equilibria happening during the actinides extraction. A protocol was elaborated to extract simultaneously all three actinides at pH = 5, then co-elute them with 0.25 mol.L -1 H 3 PO 4 . Recovery was 56 %, 74 % and 85 % for U, Pu and Am respectively. The column was then coupled to the ICP-MS. A parameter study helped defining mineralisation duration, extraction and elution flow-rates. It was then possible to propose an on-line coupling system allowing reaching detection limits lower than 0.5 mBq.L-1 for 238 U and 243 Am and lower than 5 mBq.L -1 for 239 Pu and 241 Am, for analysis duration lower than 6 hours. These analytical performances show the interest of this technique for a use in a nuclear crisis situation. (author)

  13. Validation of ISTTOK Plasma Position Controller

    International Nuclear Information System (INIS)

    Valcarcel, D. F.; Carvalho, I. S.; Carvalho, B. B.; Fernandes, H.; Silva, C.; Duarte, P.; Duarte, A.; Carvalho, P. J.; Pereira, T.

    2008-01-01

    Active control of plasma position on the ISTTOK tokamak is of extreme importance due to the inherent instability caused by an unfavourable curvature of the external equilibrium magnetic field. The consequences of this instability can be suppressed by applying a dynamic equilibrium field. A digital real-time plasma position control system for ISTTOK has been developed to perform this task. This system uses magnetic measurements to determine the plasma position and feeds the control signal to power supplies that generate the equilibrium fields. After commissioning, the results obtained have shown some discrepancies between the magnetic plasma position reconstruction and several other diagnostics, such as tomography. This discrepancy at some extent is due to the effect of the external magnetic fields on the poloidal magnetic measurements. This work presents a study that addresses this issue. In a future work it will lead to the development of a corrected plasma position algorithm, aiming at obtaining improved performance of plasma discharges and controlled plasma column displacements

  14. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    Science.gov (United States)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  15. Small Column Ion Exchange

    International Nuclear Information System (INIS)

    Huff, Thomas

    2010-01-01

    Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.

  16. Characterization of a microwave generated plasma

    International Nuclear Information System (INIS)

    Root, D.J.; Mahoney, L.; Asmussen, J.

    1986-01-01

    Recent experiments have demonstrated a microwave ion beam source without and with static magnetic fields in inert gases and in oxygen gases. This plasma generation configuration also has uses in the areas of plasma processing such as plasma etching, plasma assisted thin flim deposition and plasma assisted oxide growth. These ion beam and plasma processing applications have provided motivation to investigate microwave discharge properties, such as electron density, electron temperature, gas temperature, degree of ionization, etc., of the microwave generated plasma over a wide range of experimental operating conditions. This paper presents the results of experimental measurements which attempt to characterize the experimental microwave discharge in the absence of a static magnetic field. Measurements from a double probe, which is located in the plasma in a zero microwave field region, are presented in argon, xenon and oxygen gases. Variations of plasma density and electron temperature versus absorbed microwave power, gas pressure (0.2 m Torr to 200 m Torr) and discharge diffusion length are presented and compared to dc positive column discharge theory

  17. Mass transfer model liquid phase catalytic exchange column simulation applicable to any column composition profile

    Energy Technology Data Exchange (ETDEWEB)

    Busigin, A. [NITEK USA Inc., Ocala, FL (United States)

    2015-03-15

    Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.

  18. Beam deviation method as a diagnostic tool for the plasma focus

    International Nuclear Information System (INIS)

    Schmidt, H.; Rueckle, B.

    1978-01-01

    The application of an optical method for density measurements in cylindrical plasmas is described. The angular deviation of a probing light beam sent through the plasma is proportional to the maximum of the density in the plasma column. The deviation does not depend on the plasma dimensions, however, it is influenced to a certain degree by the density profile. The method is successfully applied to the investigation of a dense plasma focus with a time resolution of 2 ns and a spatial resolution (in axial direction) of 2 mm. (orig.) [de

  19. Current drive by asymmetrical heating in a toroidal plasma

    International Nuclear Information System (INIS)

    Gahl, J.M.

    1986-01-01

    This report describes the first experimental observation of current generation by asymmetrical heating of ions. A unidirectional fast Alfven wave launched by a slow-wave antenna inside the Texas Tech Tokamak, asymmetrically heated the ions. Measurements of the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column confirmed the current generation indirectly. Current generation, obtained in a one-species, hydrogen plasma, is a phenomenon which had not been predicted previously. Calculations of the dispersion relation for the fast Alfven wave near the fundamental cyclotron resonance in a one-species, hydrogen plasma, using warm plasma theory, support the experimental results

  20. Anomalous conductivity and electron heating in a plasma unstable to the two-stream instability

    International Nuclear Information System (INIS)

    Clark, W.H.M.; Hamberger, S.M.

    1979-01-01

    An experiment to excite the electron-ion two-stream instability in a cylindrical Q-machine plasma column is described. The mechanism for establishing a large pulsed electron drift velocity in the plasma by applying a potential difference between the end electrodes is discussed. The pulsed current-voltage characteristic of the plasma column and the temporal evolution of the electron density, drift velocity and thermal velocity are measured. In contrast with the behaviour of some computer simulations of the two-stream instability, the plasma exhibits a constant conductivity and the electron thermal velocity increases to values far in excess of the drift velocity. The electrical dissipation is consistent with the increase of the electron thermal energy, both indicating an anomalous conductivity of the same order as an empirical scaling found in earlier experiments on a toroidal discharge. (author)

  1. Drift wave turbulence in low-β plasmas

    DEFF Research Database (Denmark)

    Mikkelsen, Torben; Larsen, Søren Ejling; Pécseli, Hans

    1983-01-01

    Experimental investigations of strong turbulence associated with the radial density gradient of a rotating magnetized plasma column are reported. The experiment is designed to make Taylor's hypothesis effective, in order to allow a simple interpretation of measured frequency spectra in terms of w...... spectrum is demonstrated. Some aspects of the relative diffusion of a test-cloud of charged particles released in the turbulent field are discussed.......Experimental investigations of strong turbulence associated with the radial density gradient of a rotating magnetized plasma column are reported. The experiment is designed to make Taylor's hypothesis effective, in order to allow a simple interpretation of measured frequency spectra in terms...... of wavenumber spectra. The spectral index of the turbulent potential fluctuations is determined and the variation of the spectral intensity is investigated for varying magnetic fields. The results compare favourably with theoretical predictions. The importance of distinguishing subranges in the turbulent...

  2. A restricted access material for rapid analysis of [(11)C]-labeled radiopharmaceuticals and their metabolites in plasma

    DEFF Research Database (Denmark)

    Gillings, N.

    2009-01-01

    , combined with a monolithic analysis column in a column-switching HPLC system. RESULTS: Up to 4 ml of plasma was analyzed by this method within 4.5-7 min in a fully automated process. Because of the rapid analysis, a large number of samples could be analyzed during a 90-min PET scan. The extraction column...

  3. Conceptual design of plasma position control of SST-1 tokamak using vertical field coil

    International Nuclear Information System (INIS)

    Gulati, Hitesh Kumar; Patel, Kiritkumar B.; Dhongde, Jasraj

    2015-01-01

    SST-1 (Steady State Superconducting Tokamak) is a plasma confinement device in Institute for Plasma Research (IPR) India. SST-1 has been commissioned successfully and has been carrying out plasma experiments since the beginning of 2014 achieved a maximum plasma current of 75 kA at a central field of 1.5 T and the plasma duration ∼ 500 ms. SST-1 looks forward to carrying out elongated plasma experiments and stretching plasma pulses beyond 1s. Based on the solution of Grad-Shafranov equation the shift of plasma column center from geometrical centre of vacuum chamber is measured using various magnetic probes and flux loops installed in the machine. The closed feedback loop uses plasma current (Ip), Delta R as feedback signal and manipulate the vertical field current (Ivf). The discharge starts with feed forward loop using initially provided reference then the active feedback starts after discharge by few msec once plasma column is completely formed. The feedback loop time is of the order of 10 msec. The primary objective is to acquire plasma position control related signals, compute plasma position and generate position correction signal for VF coil power supply, communicate correction to VF coil power supply and modify VF power supply output in a deterministic time span. In this we present the methodology used for plasma horizontal displacement control using vertical field and discuss the preliminary results. (author)

  4. Numerical simulation of the ion beam generated in the diode with anode plasma column

    International Nuclear Information System (INIS)

    Vrba, P.; Sunka, P.

    1991-02-01

    The ion beam generation in a high current diode with anode plasma slab was studied. The ions were extracted from the anode plasma by the strong electric field of a deep potential well (virtual cathode), arising after the propagation of relativistic electrons through the anode plasma slab. The movement of this potential well with the front part of the ion beam leads to collective ion acceleration up to the 10 MeV energy range. (author). 7 figs., 5 refs

  5. Solid-phase extraction and HPLC assay of nicotine and cotinine in plasma and brain.

    Science.gov (United States)

    Dawson, Ralph; Messina, S M; Stokes, C; Salyani, S; Alcalay, N; De Fiebre, N C; De Fiebre, C M

    2002-01-01

    The aim of this study was to develop a simple and reliable assay for nicotine (NIC) and its major metabolite, cotinine (COT), in plasma and brain. A method was developed that uses an extraction method compatible with reverse-phase high-performance liquid chromatography (HPLC) separation and ultraviolet (UV) detection. Sequential solid-phase extraction on silica columns followed by extraction using octadecyl (C18) columns resulted in mean percent recovery (n = 5) of 51 +/- 5, 64 +/- 10, and 52 +/- 10% for NIC, COT, and phenylimidazole (PI), respectively, in spiked 1-mL serum samples. Recovery (mean +/- SEM) of the internal standard (PI) from spiked samples of nicotine-injected rats averaged 64.1 +/- 1.5% (n = 138) from plasma, and 20.7+/-0.8% (n = 128) from brain. The limits of detection of NIC in plasma samples were approximately 8 ng per mL, and of COT, 13.6 ng per mL. Further optimization of our extraction method, using slower flow rates and solid-phase extraction on silica columns, followed by C18 column extraction, yielded somewhat better recoveries (38 +/-3%) for 1-mL brain homogenates. Interassay precision (coefficient of variation) was determined on the basis of daily calibrations for 2 months and was found to be 7%, 9%, and 9% for NIC, COT, and PI, respectively, whereas intra-assay variability was 3.9% for both NIC and COT. Limited studies were performed on analytical columns for comparison of retention, resolution, asymmetry, and column capacity. We concluded that a simple two-step solid-phase extraction method, coupled with HPLC separation and UV detection, can be used routinely to measure NIC and COT in biological fluids and tissues.

  6. FOREWORD: 23rd National Symposium on Plasma Science & Technology (PLASMA-2008)

    Science.gov (United States)

    Das, A. K.

    2010-01-01

    The Twentieth Century has been a defining period for Plasma Science and Technology. The state of ionized matter, so named by Irving Langmuir in the early part of twentieth century, has now evolved in to a multidisciplinary area with scientists and engineers from various specializations working together to exploit the unique properties of the plasma medium. There have been great improvements in the basic understanding of plasmas as a many body system bound by complex collective Coulomb interactions of charges, atoms, molecules, free radicals and photons. Simultaneously, many advanced plasma based technologies are increasingly being implemented for industrial and societal use. The emergence of the multination collaborative project International Thermonuclear Experimental Reactor (ITER) project has provided the much needed boost to the researchers working on thermonuclear fusion plasmas. In addition, the other plasma applications like MHD converters, hydrogen generation, advanced materials (synthesis, processing and surface modification), environment (waste beneficiation, air and water pollution management), nanotechnology (synthesis, deposition and etching), light production, heating etc are actively being pursued in governmental and industrial sectors. For India, plasma science and technology has traditionally remained an important area of research. It was nearly a century earlier that the Saha ionization relation pioneered the way to interpret experimental data from a vast range of near equilibrium plasmas. Today, Indian research contributions and technology demonstration capabilities encompass thermonuclear fusion devices, nonlinear plasma phenomena, plasma accelerators, beam plasma interactions, dusty and nonneutral plasmas, industrial plasmas and plasma processing of materials, nano synthesis and structuring, astrophysical and space plasmas etc. India's participation in the ITER programme is now reflected in increased interest in the research and development

  7. Equivalent effect of neutral gas pressure and transverse magnetic field in low-pressure glow discharge plasma

    International Nuclear Information System (INIS)

    Toma, M.; Rusu, Ioana; Pohoata, V.; Mihaila, I.

    2001-01-01

    In the paper it is emphasized the equivalent effect of the neutral gas pressure and the action of a transverse magnetic field (TMF), respectively, on a striated positive plasma column. Experimental and theoretical results prove that the distance between striations has the same variation under the influence of both neutral gas pressure and the action of TMF. The pressure modification as well as the action of a TMF can induce ionization instability in the plasma column which explains the standing striation appearance. (authors)

  8. An experimental study of the ion energy balance of a magnetized plasma

    International Nuclear Information System (INIS)

    Pots, B.F.M.; Hooff, P. van; Schram, D.C.; Sijde, B. van der

    1981-01-01

    A report is given on an experimental study of the ion energy balance of the magnetized and current-driven plasma f a hollow cathode discharge. The balance appears to be classical. At the axis of the plasma column the electron-ion Coulomb interaction is in equilibrium with the ion-neutral interaction. No significant influence on the energy balance by the spontaneously appearing plasma turbulence is formed. (author)

  9. Calculus of the amplification and absorption coefficients of the electromagnetic waves in a cylindrical over dense plasma

    International Nuclear Information System (INIS)

    Arzate P, N.

    1994-01-01

    Based on the fundamental theory of cylindrical waveguides and resonant cavities, the main characteristic parameters of the microwave plasma source reported in [1] are calculated. The absorption coefficient of an electromagnetic wave which is excited in H 11 mode in a cylindrical waveguide that contains a cold, inhomogeneous and magnetized plasma column is determined by using the perturbative method describe in [2]. In similar way, due to the presence of the plasma column, the shifts of the resonant frequency and of the inverse of the quality of a cylindrical resonant cavity where a TE 111 mode is oscilating are obtained. Finally, based on the linear theory, an analysis of the penetration of electromagnetic fields in a semi-bounded plasma and a plasma layer is done. The reflexion, transmission and absorption coefficients of H waves for the cases of an isotropic homogeneous and weak inhomogeneous plasma are calculated. (Author)

  10. Two generalizations of column-convex polygons

    International Nuclear Information System (INIS)

    Feretic, Svjetlan; Guttmann, Anthony J

    2009-01-01

    Column-convex polygons were first counted by area several decades ago, and the result was found to be a simple, rational, generating function. In this work we generalize that result. Let a p-column polyomino be a polyomino whose columns can have 1, 2, ..., p connected components. Then column-convex polygons are equivalent to 1-convex polyominoes. The area generating function of even the simplest generalization, namely 2-column polyominoes, is unlikely to be solvable. We therefore define two classes of polyominoes which interpolate between column-convex polygons and 2-column polyominoes. We derive the area generating functions of those two classes, using extensions of existing algorithms. The growth constants of both classes are greater than the growth constant of column-convex polyominoes. Rather tight lower bounds on the growth constants complement a comprehensive asymptotic analysis.

  11. Optical emission spectra of a copper plasma produced by a metal vapour vacuum arc plasma source

    International Nuclear Information System (INIS)

    Yotsombat, B.; Poolcharuansin, P.; Vilaithong, T.; Davydov, S.; Brown, I.G.

    2001-01-01

    Optical emission spectroscopy in the range 200-800 nm was applied for investigation of the copper plasma produced by a metal vapour vacuum arc plasma source. The experiments were conducted for the cases when the plasma was guided by straight and Ω-shaped curved solenoids as well as without solenoids, and also for different vacuum conditions. It was found that, besides singly- and doubly-charged ions, a relatively high concentration of excited neutral copper atoms was present in the plasma. The relative fraction of excited atoms was much higher in the region close to the cathode surface than in the plasma column inside the solenoid. The concentration of excited neutral, singly- and doubly-ionized atoms increased proportionally when the arc current was increased to 400 A. Some weak lines were attributed to more highly ionized copper species and impurities in the cathode material. (author)

  12. Simulations of diocotron instability using a special-purpose computer, MDGRAPE-2

    International Nuclear Information System (INIS)

    Yatsuyanagi, Yuichi; Kiwamoto, Yasuhito; Ebisuzaki, Toshikazu; Hatori, Tadatsugu; Kato, Tomokazu

    2003-01-01

    The diocotron instability in a low-density non-neutral electron plasma is examined via numerical simulations. For the simulations, a current-vortex filament model and a special-purpose computer, MDGRAPE-2 are used. In the previous work, a simulation method based on the current-vortex filament model, which is called 'current-vortex method', is developed. It is assumed that electric current and vorticity have discontinuous filamentary distributions, and both point electric current and point vortex are confined in a filament, which is called 'current-vortex filament'. In this paper, the current-vortex method with no electric current is applied to simulations of the non-neutral electron plasma. This is equivalent to the traditional point-vortex method. MDGRAPE-2 was originally designed for molecular dynamics simulations. It accelerates calculations of the Coulomb interactions, the van der Waals interactions and so on. It can also be used to accelerate calculations of the Biot-Savart integral. The diocotron modes reproduced by the simulations agree with the result predicted by linear theory. This indicates that the current-vortex method is applicable to problems of the non-neutral plasma. The linear growth rates of the diocotron instability in the simulations also agree with the theoretical ones. This implies that MDGRAPE-2 gives the sufficiently accurate results for the calculations of the current-vortex method. A mechanism of merging of electron clumps is demonstrated by the simulations. It is concluded that the electric field induced by the conducting wall makes the nonlinear stage unstable and causes the clumps to merge

  13. Trapping of positrons in a Penning Malmberg trap in the view of accumulating them with the use of a pulsed beam

    International Nuclear Information System (INIS)

    Dupre, P.

    2011-09-01

    The weak equivalence principle, a fundament of Einstein general relativity, states that gravitational mass and inertial mass are equal whatever the body. This equivalence principle has never been directly tested with antimatter. The GBAR (Gravitational Behaviour of Antimatter at Rest) experiment intends to test it by measuring the acceleration of ultra cold anti-hydrogens in free fall. The production of such anti-atoms requires a pulse of about 10 10 positrons in a few tens of nanoseconds. This thesis focuses on the development of a new accumulation technique of positrons in a Penning-Malmberg trap in order to create this pulse. This new method is an improvement of the accumulation technique of Oshima et al.. This technique requires a non-neutral electron plasma to cool down positrons in the trap in order to confine them. A continuous beam delivers positrons and the trapping efficiency is about 0.4%. The new method needs a positron pulsed beam and the method efficiency is estimated at 80%. A part of this thesis was performed at Riken (Tokyo) on the trap of Oshima et al. to study the behavior of non-neutral plasmas in this type of trap and the first accumulation method. A theoretical model was developed to simulate the positron trapping efficiency. The description and the systematic study of the new accumulation technique with a pulsed positron beam are presented. They includes notably the optimization through simulation of the electromagnetic configuration of the trap and of the parameters of the used non-neutral plasmas. (author)

  14. Positron Source from Betatron X-rays Emitted in a Plasma Wiggler

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.K.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA; Barnes, C.D.; Decker, F.J.; Hogan, M.J.; Iverson, R.H.; Krejcik, P.; O' Connell, C.L.; Siemann, R.; Walz, D.R.; /SLAC; Deng, S.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2006-04-21

    In the E-167 plasma wakefield accelerator (PWFA) experiments in the Final Focus Test Beam (FFTB) at the Stanford Linear Accelerator Center (SLAC), an ultra-short, 28.5 GeV electron beam field ionizes a neutral column of Lithium vapor. In the underdense regime, all plasma electrons are expelled creating an ion column. The beam electrons undergo multiple betatron oscillations leading to a large flux of broadband synchrotron radiation. With a plasma density of 3 x 10{sup 17}cm{sup -3}, the effective focusing gradient is near 9 MT/m with critical photon energies exceeding 50 MeV for on-axis radiation. A positron source is the initial application being explored for these X-rays, as photo-production of positrons eliminates many of the thermal stress and shock wave issues associated with traditional Bremsstrahlung sources. Photo-production of positrons has been well-studied; however, the brightness of plasma X-ray sources provides certain advantages. In this paper, we present results of the simulated radiation spectra for the E-167 experiments, and compute the expected positron yield.

  15. Assay of fluconazole by high-performance liquid chromatography with a mixed-phase column.

    OpenAIRE

    Wallace, J E; Harris, S C; Gallegos, J; Foulds, G; Chen, T J; Rinaldi, M G

    1992-01-01

    A mixed-phase liquid chromatographic column was used to assay fluconazole in plasma, serum, and cerebrospinal fluid. The assay was linear from 0.2 to 20 micrograms/ml, with an average coefficient of variation of less than 5%. The partitioning of the drug between serum and cerebrospinal fluid was determined for 34 patients. The method was demonstrated to be suitable for both pharmacokinetic studies and monitoring of patients receiving treatment with this antifungal agent.

  16. Capillary column switching restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry system for simultaneous and direct analysis of drugs in biofluids.

    Science.gov (United States)

    Santos-Neto, Alvaro J; Markides, Karin E; Sjöberg, Per J R; Bergquist, Jonas; Lancas, Fernando M

    2007-08-15

    Capillary online restricted-access media-liquid chromatography-electrospray ionization-tandem mass spectrometry (RAM-LC-ESI-MS/MS) for direct analysis of drugs and metabolites spiked in biological fluids was developed. Using a column switching setup it was possible to perform effective sample preparation and analysis of raw biological fluids (plasma and urine) without matrix effects in the electrospray mass spectrometric detection step. The peak focusing efficiency of the extraction column was more effective in backflush compared to foreflush mode. The system was able to concentrate diminished samples of polar drugs and their metabolites reaching quantifiable results as low as 1 ng/mL utilizing a sample volume of only 333 nL of biofluids. New column hardware was developed to circumvent clogging problems experienced with plasma injections. The glass fiber filter frit, which is commonly used, was replaced with a short piece of 20 microm i.d. fused silica capillary. The extraction columns were able to handle up to 60 injections and showed a high loading capacity, making the saturation of the MS detector the limiting factor on the linear dynamic range. The simultaneous separation and detection of 10 drugs and metabolites was obtained in 8 min of analysis, including the online sample preparation and enrichment step.

  17. SPQR II: A beam-plasma interaction experiment

    International Nuclear Information System (INIS)

    Bimbot, R.; Della-Negra, S.; Gardes, D.

    1986-01-01

    SPQR II is an interaction experiment designed to probe energy -and charge-exchange of C/sup n/ + ions at 2 MeV/a.m.u., flowing through a fully ionized plasma column of hydrogen with nl-script = 10 19 e-cm -2 at T = 5 eV

  18. Kinetic theory of the positive column of a low-pressure discharge in a transverse magnetic field

    International Nuclear Information System (INIS)

    Londer, Ya. I.; Ul’yanov, K. N.

    2011-01-01

    The influence of a transverse magnetic field on the characteristics of the positive column of a planar low-pressure discharge is studied theoretically. The motion of magnetized electrons is described in the framework of a continuous-medium model, while the ion motion in the ambipolar electric field is described by means of a kinetic equation. Using mathematical transformations, the problem is reduced to a secondorder ordinary differential equation, from which the spatial distribution of the potential is found in an analytic form. The spatial distributions of the plasma density, mean plasma velocity, and electric potential are calculated, the ion velocity distribution function at the plasma boundary is found, and the electron energy as a function of the magnetic field is determined. It is shown that, as the magnetic field rises, the electron energy increases, the distributions of the plasma density and mean plasma velocity become asymmetric, the maximum of the plasma density is displaced in the direction of the Ampère force, and the ion flux in this direction becomes substantially larger than the counter-directed ion flux.

  19. Development of spent salt treatment technology by zeolite column system. Performance evaluation of zeolite column

    International Nuclear Information System (INIS)

    Miura, Hidenori; Uozumi, Koichi

    2009-01-01

    At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)

  20. The design of central column protection tiles for the TCV tokamak

    International Nuclear Information System (INIS)

    Pitts, R.A.; Chavan, R.; Moret, J.M.

    1999-01-01

    The large variety of plasma shapes produced in the TCV tokamak places unique demands on the plasma facing surfaces. In particular, the central column graphite armour tiles are solicited during the creation of all TCV plasmas and function as power handling surfaces for both limited and diverted discharges. The higher power flux densities accompanying the addition of electron cyclotron heating systems have necessitated a new, optimized, design for these tiles. The optimization process and the subsequent new tile design are described. A basic 'two point' model of the scrape-off layer plasma in conjunction with TCV equilibrium reconstructions and a simplified representation of the local magnetic field line geometry are used to impose simulated power flux densities onto a parametric toroidal tile contour. The thermo-mechanical response of the tile is then investigated via full 3-D finite element simulations accounting for the non-linear temperature dependence of the graphite thermal diffusivity and radiation from the tile surface. The final design choice is a compromise between the requirements for adequate power handling for a range of magnetic configurations, the need to protect against tile edge misalignment in the presence of grazing field line angles of incidence and the space restrictions imposed by vacuum vessel design. (author)

  1. Ground penetrating radar using a microwave radiated from laser-induced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, H; Tanaka, K A [Graduate School of Engineering and Institute of Laser Engineering, Suita, Osaka University (Japan); Yamaura, M; Shimada, Y; Fujita, M [Institute for Laser Technology, Suita, Osaka (Japan)], E-mail: nakajima-h@ile.osaka-u.ac.jp

    2008-05-01

    A plasma column radiates a microwave to surroundings when generated with laser irradiation. Using such a microwave, we are able to survey underground objects and architectures from a remote place. In this paper, the microwave radiated from a plasma column induced by an intense laser ({approx} 10{sup 9} W/cm{sup 2}) were measured. Additionally, a proof test of this method was performed by searching an underground aluminum disk (26 cm in diameter, 1 cm in depth, and 1 m apart from a receiving antenna). As the result, the characteristics of the radiated microwave were clarified, and strong echoes corresponding to the edges of an aluminum disk were found. Based on these results, the feasibility of a ground penetrating radar was verified.

  2. Current limitation and formation of plasma double layers in a non-uniform magnetic field

    International Nuclear Information System (INIS)

    Plamondon, R.; Teichmann, J.; Torven, S.

    1986-07-01

    Formation of strong double layers has been observed experimentally in a magnetised plasma column maintained by a plasma source. The magnetic field is approximately axially homogenous except in a region at the anode where the electric current flows into a magnetic mirror. The double layer has a stationary position only in the region of non-uniform magnetic field or at the aperture separating the source and the plasma column. It is characterized by a negative differential resistance in the current-voltage characteristic of the device. The parameter space,where the double layer exists, has been studied as well as the corresponding potential profiles and fluctuation spectra. The electric current and the axial electric field are oppositely directed between the plasma source and a potential minimum which is formed in the region of inhomogeneous magnetic field. Electron reflection by the resulting potential barrier is found to be an important current limitation mechanism. (authors)

  3. Performance evaluation of a rectifier column using gamma column scanning

    Directory of Open Access Journals (Sweden)

    Aquino Denis D.

    2017-12-01

    Full Text Available Rectifier columns are considered to be a critical component in petroleum refineries and petrochemical processing installations as they are able to affect the overall performance of these facilities. It is deemed necessary to monitor the operational conditions of such vessels to optimize processes and prevent anomalies which could pose undesired consequences on product quality that might lead to huge financial losses. A rectifier column was subjected to gamma scanning using a 10-mCi Co-60 source and a 2-inch-long detector in tandem. Several scans were performed to gather information on the operating conditions of the column under different sets of operating parameters. The scan profiles revealed unexpected decreases in the radiation intensity at vapour levels between trays 2 and 3, and between trays 4 and 5. Flooding also occurred during several scans which could be attributed to parametric settings.

  4. Electrostatic modes as a diagnostic in Penning-trap experiments

    International Nuclear Information System (INIS)

    Weimer, C.S.; Bollinger, J.J.; Moore, F.L.; Wineland, D.J.

    1994-01-01

    A subset of the electrostatic modes of a cold cloud of electrons, a non-neutral electron plasma, trapped in a Penning trap has been observed and identified using a recent theoretical model. The detection of these modes is accomplished using electronic techniques which could apply to any ion species. The modes are observed in the low-density, low-rotation limit of the cloud where the cloud approaches a two-dimensional charged disk. We observe both axially symmetric and asymmetric drumhead modes. The shape, rotation frequency, and density of the cloud are found in a real-time nondestructive manner by measuring the frequency of these modes. In addition, it is found that radio-frequency sideband cooling compresses the cloud, increasing its density. The ability to measure and control the density of a trapped ion cloud might be useful for experiments on low-temperature ion--neutral-atom collisions, recombination rates, and studies of the confinement properties of non-neutral plasmas

  5. Single column and two-column H-D-T distillation experiments at TSTA

    International Nuclear Information System (INIS)

    Yamanishi, T.; Yoshida, H.; Hirata, S.; Naito, T.; Naruse, Y.; Sherman, R.H.; Bartlit, J.R.; Anderson, J.L.

    1988-01-01

    Cryogenic distillation experiments were peformed at TSTA with H-D-T system by using a single column and a two-column cascade. In the single column experiment, fundamental engineering data such as the liquid holdup and the HETP were measured under a variety of operational condtions. The liquid holdup in the packed section was about 10 /approximately/ 15% of its superficial volume. The HETP values were from 4 to 6 cm, and increased slightly with the vapor velocity. The reflux ratio had no effect on the HETP. For the wo-colunn experiemnt, dynamic behavior of the cascade was observed. 8 refs., 7 figs., 2 tabs

  6. ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION

    International Nuclear Information System (INIS)

    Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

    2012-01-01

    We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 10 21 cm –2 , which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 10 22 cm –2 at z = 0. Using observations of the column density distribution, we argue that the H I-H 2 transition does not cause the turnover at N H I ≈ 10 21 cm –2 but can plausibly explain the turnover at N H I ∼> 10 22 cm –2 . We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ∼ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

  7. Grain dynamics and inter-grain coupling in dusty plasma Coulomb crystals

    International Nuclear Information System (INIS)

    Rahman, H.U.; Mohideen, U.; Smith, M.A.; Rosenberg, M.; Mendis, D.A.

    2001-01-01

    We review our results on the lattice structure and the lattice dynamics of dusty plasma Coulomb crystals formed in rectangular conductive grooves. The basic structure appears to be made of mutually repulsive columns of grains confined by the walls of the groove. The columns are oriented along the direction of the electrode sheath electric field. Inter-grain coupling as a function of plasma temperature and density were investigated by measurement of these parameters. A simple phenomenological model wherein the inter-grain spacing along the column results from an attractive electric field induced dipole-dipole force balanced by a repulsive monopole Coulomb force is consistent with observed features of the Coulomb crystal. In addition, here we present some preliminary measurements of the vibration and rotation dynamics of the individual grains in the Coulomb crystal. The thermal energy of the dust grain thus calculated is much less than the inter-grain Coulomb potential energy as required for the formation of stable structures. Also the observed rotational frequency is consistent with the assumption of thermal equilibrium between the dust grains and the neutral gas. (orig.)

  8. Adiabatic packed column supercritical fluid chromatography using a dual-zone still-air column heater.

    Science.gov (United States)

    Helmueller, Shawn C; Poe, Donald P; Kaczmarski, Krzysztof

    2018-02-02

    An approach to conducting SFC separations under pseudo-adiabatic condition utilizing a dual-zone column heater is described. The heater allows for efficient separations at low pressures above the critical temperature by imposing a temperature profile along the column wall that closely matches that for isenthalpic expansion of the fluid inside the column. As a result, the efficiency loss associated with the formation of radial temperature gradients in this difficult region can be largely avoided in packed analytical scale columns. For elution of n-octadecylbenzene at 60 °C with 5% methanol modifier and a flow rate of 3 mL/min, a 250 × 4.6-mm column packed with 5-micron Kinetex C18 particles began to lose efficiency (8% decrease in the number of theoretical plates) at outlet pressures below 142 bar in a traditional forced air oven. The corresponding outlet pressure for onset of excess efficiency loss was decreased to 121 bar when the column was operated in a commercial HPLC column heater, and to 104 bar in the new dual-zone heater operated in adiabatic mode, with corresponding increases in the retention factor for n-octadecylbenzene from 2.9 to 6.8 and 14, respectively. This approach allows for increased retention and efficient separations of otherwise weakly retained analytes. Applications are described for rapid SFC separation of an alkylbenzene mixture using a pressure ramp, and isobaric separation of a cannabinoid mixture. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Influence of pressure on the properties of chromatographic columns. II. The column hold-up volume.

    Science.gov (United States)

    Gritti, Fabrice; Martin, Michel; Guiochon, Georges

    2005-04-08

    The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C18-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C18 (10% carbon) and the Symmetry-C18 (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C18-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.

  10. Properties and structure of a plasma non-neutral shock

    International Nuclear Information System (INIS)

    Hu Yemin; Hu Xiwei

    2004-01-01

    The shock is described by the Navier-Stokes equations of the electron and ion fluids, and coupled with Poisson's equation for the self-induced electric field. Profiles of the flow and electric variables in the weak or moderate shock front with or without current for different Debye lengths are presented. Comparison of profiles of flow and electric variables in the front for different heat flow modes is given

  11. Strict calculation of electron energy distribution functions in inhomogeneous plasmas

    International Nuclear Information System (INIS)

    Winkler, R.

    1996-01-01

    It is objective of the paper to report on strict calculations of the velocity or energy distribution function function and related macroscopic properties of the electrons from appropriate electron kinetic equations under various plasma conditions and to contribute to a better understanding of the electron behaviour in inhomogeneous plasma regions. In particular, the spatial relaxation of plasma electrons acted upon by uniform electric fields, the response of plasma electrons on spatial disturbances of the electric field, the electron kinetics under the impact of space charge field confinement in the dc column plasma and the electron velocity distribution is stronger field as occurring in the electrode regions of a dc glow discharge is considered. (author)

  12. Plasma metabolism of apolipoprotein A-IV in humans

    International Nuclear Information System (INIS)

    Ghiselli, G.; Krishnan, S.; Beigel, Y.; Gotto, A.M. Jr.

    1986-01-01

    As assessed by molecular sieve chromatography and quantitation by a specific radioimmunoassay, apoA-IV is associated in plasma with the triglyceride-rich lipoproteins, to a high density lipoprotein (HDL) subfraction of smaller size than HDL3, and to the plasma lipoprotein-free fraction (LFF). In this study, the turnover of apoA-IV associated to the triglyceride-rich lipoproteins, HDL and LFF was investigated in vivo in normal volunteers. Human apoA-IV isolated from the thoracic duct lymph chylomicrons was radioiodinated and incubated with plasma withdrawn from normal volunteers after a fatty meal. Radioiodinated apoA-IV-labeled triglyceride-rich lipoproteins, HDL, and LFF were then isolated by chromatography on an AcA 34 column. Shortly after the injection of the radioiodinated apoA-IV-labeled triglyceride-rich lipoproteins, most of the radioactivity could be recovered in the HDL and LFF column fractions. On the other hand, when radioiodinated apoA-IV-labeled HDL or LFF were injected, the radioactivity remained with the originally injected fractions at all times. The residence time in plasma of 125 I-labeled apoA-IV, when injected in association with HDL or LFF, was 1.61 and 0.55 days, respectively. When 125 I-labeled apoA-IV was injected as a free protein, the radioactivity distributed rapidly among the three plasma pools in proportion to their mass. The overall fractional catabolic rate of apoA-IV in plasma was measured in the three normal subjects and averaged 1.56 pools per day. The mean degradation rate of apoA-IV was 8.69 mg/kg X day

  13. New features of current-driven low-frequency instabilities in a Q-machine plasma

    International Nuclear Information System (INIS)

    Dimitriu, Dan-Gheorghe; Ignatescu, Valerian; Lozneanu, Erzilia; Sanduloviciu, Mircea; Ionita, Codrina; Schrittwieser, Roman Wolfgang

    2001-01-01

    Among the instabilities in a low-density magnetized plasma column, the electrostatic ion-cyclotron instability (EICI) and the potential relaxation instability (PRI) are the best known and most thoroughly investigated. Both instabilities are excited by drawing an electron current parallel to the magnetic field towards a circular collector (CO), which is inserted into the plasma column perpendicular to the axis. For the PRI, the radius of CO must be considerably larger than the ion gyroradius so that the ion trajectories can be approximated as one-dimensional. For the EICI, the radius of CO must be considerably smaller than that of the plasma column, but also larger than one ion gyroradius. A transition from the PRI into the EICI was reported earlier. A certain range of CO radii was found where both instabilities could be excited simultaneously. We report on a strong modulation of the EICI by the PRI, obtained for gradually increasing the CO bias, with the EICI appearing at first, and later the PRI. The EICI frequency was about four times larger than that of the PRI. The modulation not only affects the amplitude but also the frequency of the EICI. This leads to the formation of sidebands in the spectrum around f EICI with a frequency difference equal to ± f PRI . In addition, we find that the EICI frequency depends not only on the magnetic field strength but also on the CO current. Our data also show a strong non-linear dependence of the PRI frequency on the magnetic field strength. To explain these features, we propose a new phenomenological model, which is able to clarify the role of complex space charge configurations for low frequency instabilities in a low-density magnetized plasma column. (authors)

  14. Characteristics of the self-excited ionization waves in a magnetized positive column

    International Nuclear Information System (INIS)

    Maruyama, Takeo; Yamamura, Yasuhiro; Takano, Saburo; Miura, Kosuke; Imazu, Shingo.

    1979-01-01

    In the past, metastable atoms were not considered in the investigations of ionization waves generated in a positive column weakly ionized. However, metastable atoms seem to be important for the generation of ionization waves, and there are many unknown factors. In this paper, the fundamental equations and dispersion relation are explained under the assumption of axi-symmetrical positive column plasma placed in a uniform magnetic field, and the direct ionization frequency and excitation frequency, cumulative ionization coefficient, electron density and metastable atom density, the energy loss factor for electrons, the dependence of plasma quantities on magnetic field and dispersion characteristics are calculated. Experiments have been conducted using Ne gas in a discharge tube of 80 cm long and 1 cm radius with heated oxide cathode. Magnetic field was obtained with a solenoid coil of 75 cm long, 9 cm I.D. and 27 cm O.D. The axially uniform magnetic field was in the range of 35 to 40 cm. As the results, the following points have become clear. (1) The number of waves, angular frequency and phase velocity of ionization waves decrease with the increase of magnetic field. (2) By the consideration of the presence of metastable atoms, the theoretical values were improved pretty well and agreed with the experimental values qualitatively and quantitatively. (3) Longitudinal magnetic field has the effect of suppressing the growth of ionization waves because of the reduction of time and spatial growth rates with the increase of magnetic field. (Wakatsuki, Y.)

  15. Plasma instability of a vacuum arc centrifuge

    International Nuclear Information System (INIS)

    Hole, M.J.; Dallaqua, R.S.; Simpson, S.W.; Del Bosco, E.

    2002-01-01

    Ever since conception of the vacuum arc centrifuge in 1980, periodic fluctuations in the ion saturation current and floating potential have been observed in Langmuir probe measurements in the rotation region of a vacuum arc centrifuge. In this work we develop a linearized theoretical model to describe a range of instabilities in the vacuum arc centrifuge plasma column, and then test the validity of the description through comparison with experiment. We conclude that the observed instability is a 'universal' instability, driven by the density gradient, in a plasma with finite conductivity

  16. Mode suppression of a two-dimensional potential relaxation instability in a weakly magnetized discharge plasma

    Science.gov (United States)

    Gyergyek, T.; Čerček, M.; Jelić, N.; Stanojević, M.

    1993-05-01

    A potential relaxation instability (PRI) is modulated by an external signal using an additional grid to modulate the radial plasma potential profile in a magnetized plasma column in a linear magnetized discharge plasma device. It is observed that the electrode current oscillations follow the van der Pol equation with an external forcing term, and the linear growth rate of the instability is measured.

  17. Influence of DC arc jets on flow fields analyzed by an integrated numerical model for a DC-RF hybrid plasma

    International Nuclear Information System (INIS)

    Seo, Jun Ho; Park, Jin Myung; Hong, Sang Hee

    2008-01-01

    The influence of DC arc jets on the flow fields in a hybrid plasma torch is numerically analyzed by an integrated direct current-radio frequency (DC-RF) plasma model based on magneto-hydrodynamic formulations. The calculated results reveal that the increase in DC arc gas flow rate raises the axial flow velocity along the central column of the DC-RF hybrid plasma together with the enhanced backflow streams in the peripheral wall region. The temperature profiles on the torch exit plane are little affected due to the reheating process of the central column by the combined RF plasma. Accordingly, the exit enthalpy emitted from the DC-RF hybrid torch can be concentrated to the central column of the plasma and controlled by adjusting the DC arc gas flow rate. The swirl in the sheath gas flow turns out to have the opposite effect on the DC arc gas flow rate. The swirling motion of the sheath gas can reduce the back flows near the induction tube wall as well as the axial velocities in the central column of the plasma. Accordingly, the swirl in the sheath gas flow can be used for the functional operation of the DC-RF hybrid plasma along with the DC arc gas flow rate to suppress the back flows at the wall region and to reduce the excessive interactions between the DC arc jet and the ambient RF plasmas. The effects of DC input current on the flow fields of hybrid plasma are similar to those of the DC arc gas flow rate, but the axial velocities for the higher current relatively quickly decay along the centerline. This is in contrast to the increase in the axial velocity remaining in proportion to the increase in the DC arc gas flow rate all the way up to the exit of the DC-RF hybrid plasma. Accordingly, the present integrated numerical analysis suggests that the hybrid plasma field profiles and the entrainment of ambient air from the torch exit are controllable by adjusting the DC arc gas flow rate, the DC input current and swirl in the sheath gas flow taking advantage of

  18. Admittance Scanning for Whole Column Detection.

    Science.gov (United States)

    Stamos, Brian N; Dasgupta, Purnendu K; Ohira, Shin-Ichi

    2017-07-05

    Whole column detection (WCD) is as old as chromatography itself. WCD requires an ability to interrogate column contents from the outside. Other than the obvious case of optical detection through a transparent column, admittance (often termed contactless conductance) measurements can also sense changes in the column contents (especially ionic content) from the outside without galvanic contact with the solution. We propose here electromechanically scanned admittance imaging and apply this to open tubular (OT) chromatography. The detector scans across the column; the length resolution depends on the scanning velocity and the data acquisition frequency, ultimately limited by the physical step resolution (40 μm in the present setup). Precision equal to this step resolution was observed for locating an interface between two immiscible liquids inside a 21 μm capillary. Mechanically, the maximum scanning speed was 100 mm/s, but at 1 kHz sampling rate and a time constant of 25 ms, the highest practical scan speed (no peak distortion) was 28 mm/s. At scanning speeds of 0, 4, and 28 mm/s, the S/N for 180 pL (zone length of 1.9 mm in a 11 μm i.d. column) of 500 μM KCl injected into water was 6450, 3850, and 1500, respectively. To facilitate constant and reproducible contact with the column regardless of minor variations in outer diameter, a double quadrupole electrode system was developed. Columns of significant length (>1 m) can be readily scanned. We demonstrate its applicability with both OT and commercial packed columns and explore uniformity of retention along a column, increasing S/N by stopped-flow repeat scans, etc. as unique applications.

  19. Current density distribution during disruptions and sawteeth in a simple model of plasma current in a tokamak

    International Nuclear Information System (INIS)

    Stefanovskii, A. M.

    2011-01-01

    The processes that are likely to accompany discharge disruptions and sawteeth in a tokamak are considered in a simple plasma current model. The redistribution of the current density in plasma is supposed to be primarily governed by the onset of the MHD-instability-driven turbulent plasma mixing in a finite region of the current column. For different disruption conditions, the variation in the total plasma current (the appearance of a characteristic spike) is also calculated. It is found that the numerical shape and amplitude of the total current spikes during disruptions approximately coincide with those measured in some tokamak experiments. Under the assumptions adopted in the model, the physical mechanism for the formation of the spikes is determined. The mechanism is attributed to the diffusion of the negative current density at the column edge into the zero-conductivity region. The numerical current density distributions in the plasma during the sawteeth differ from the literature data.

  20. The effects of carbide column to swelling potential and Atterberg limit on expansive soil with column to soil drainage

    Science.gov (United States)

    Muamar Rifa'i, Alfian; Setiawan, Bambang; Djarwanti, Noegroho

    2017-12-01

    The expansive soil is soil that has a potential for swelling-shrinking due to changes in water content. Such behavior can exert enough force on building above to cause damage. The use of columns filled with additives such as Calcium Carbide is done to reduce the negative impact of expansive soil behavior. This study aims to determine the effect of carbide columns on expansive soil. Observations were made on swelling and spreading of carbides in the soil. 7 Carbide columns with 5 cm diameter and 20 cm height were installed into the soil with an inter-column spacing of 8.75 cm. Wetting is done through a pipe at the center of the carbide column for 20 days. Observations were conducted on expansive soil without carbide columns and expansive soil with carbide columns. The results showed that the addition of carbide column could reduce the percentage of swelling by 4.42%. Wetting through the center of the carbide column can help spread the carbide into the soil. The use of carbide columns can also decrease the rate of soil expansivity. After the addition of carbide column, the plasticity index value decreased from 71.76% to 4.3% and the shrinkage index decreased from 95.72% to 9.2%.

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

    Science.gov (United States)

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

    2016-09-01

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

  2. Behavior of a plasma in a high-density gas-embedded Z-pinch configuration

    International Nuclear Information System (INIS)

    Shlachter, J.S.

    1982-05-01

    The theoretical analysis of a high density Z-pinch (HDZP) begins with an examination of the steady state energy balance between ohmic heating and bremsstrahlung radiation losses for a plasma column in pressure equilibrium. The model is then expanded to include the time-varying internal energy and results in a quasi-equilibrium prescription for the load current through a constant radius plasma channel. This set of current waveforms is useful in the design of experimental systems. The behavior of a plasma for physically realizable conditions is first examined by allowing adiabatic changes in the column radius. A more complete model is then developed by incorporating inertial effects into the momentum equation, and the resultant global MHD computational model is compared with more sophisticated, and costly, one- and two-dimensional computer simulations. These comparisons demonstrate the advantages of the global MHD description over previously developed zero-dimensional models

  3. Thermal process of an air column

    International Nuclear Information System (INIS)

    Lee, F.T.

    1994-01-01

    Thermal process of a hot air column is discussed based on laws of thermodynamics. The kinetic motion of the air mass in the column can be used as a power generator. Alternatively, the column can also function as a exhaust/cooler

  4. EDITORIAL: 80 Years of Plasma 80 Years of Plasma

    Science.gov (United States)

    Franklin, R. N.; Braithwaite, N. St J.

    2009-02-01

    Irving Langmuir proposed the term 'plasma' in a paper in 1928 (Proc. Natl Acad. Sci. USA 14 627-637) to describe a 'region containing balanced charges of ions and electrons'. There does not appear to be any record of the thinking behind this proposal, so it is difficult to be definitive. One idea is that since the Greek word 'plasma' was used to describe a mouldable fluid, 'neon' lighting, with its almost limitless ability to provide colourful shapes, provided the inspiration. Another relates to the prior medical use in relation to blood with its variety of different 'corpuscles' and that the essential description of the positive column required one to recognize at least the role of the separate species of electrons, ions and gas atoms. Tonks, when questioned thirty years later, was inclined to the latter idea, but it is unlikely that we shall ever know for certain. (See postscript added December 2008.) Forty years ago most of the interest in terrestrial plasmas was centred on fusion and the prospect of thus solving the world's energy problems; the quest continues. However, since then a whole new industry has developed. It emerged in the 1970s as an imaginative way to remove the photoresist layers used in patterning semiconductor wafers. Slowly but steadily, plasma-based 'dry' processes began to displace the traditional wet chemistry processes of cleaning, etching and depositing by which the first generation of integrated circuits had been made. Plasma technology offered higher yields while accommodating the complexity of ever-shrinking feature size, driving the microelectronic revolution for almost four decades. Langmuir certainly ushered in an exciting branch of physics when he introduced the term plasma. We have included as Appendix I a condensed CV for Irving Langmuir to show, amongst other things, the early influences on his subsequent life. An interlude in Paris gave him a taste of the wider world of Europe. His subsequent schooling in the United States led

  5. On plasma-neutral gas interaction

    International Nuclear Information System (INIS)

    Venkataramani, N.; Mattoo, S.K.

    1980-01-01

    The importance of plasma-neutral gas interaction layer has been emphasized by pointing out its application to a wide variety of physical phenomena. The interaction of a magnetised plasma stream penetrating a neutral gas cloud is discussed in the light of Alfven's critical velocity and Varma's threshold velocity on the ionising interaction. Interaction of a moving magnetised plasma with a stationary neutral gas has been studied and described. The device comprises of a plasma gun and an interaction region where neutral gas cloud is injected. The interaction region is provided with a transverse magnetic field of upto 1000 G. Several diagnostics deployed at the interaction region to make measurements on the macroscopic parameters of plasma and neutral gas are described. The parameters of discharge circuits are measured with high current and voltage probes. An interaction between a magnetised plasma stream and a neutral gas cloud is demonstrated. It is shown that this interaction does not have Varma's threshold on their relative velocity. The Alfven's critical velocity phenomenon is shown to depend on the integrated column neutral gas density that a plasma stream encounters while penetrating through it and not on the neutral gas density in the range of 10 17 -10 21 m -3 . (auth.)

  6. Solvent extraction columns

    International Nuclear Information System (INIS)

    Middleton, P.; Smith, J.R.

    1979-01-01

    In pulsed columns for use in solvent extraction processes, e.g. the reprocessing of nuclear fuel, the horizontal perforated plates inside the column are separated by interplate spacers manufactured from metallic neutron absorbing material. The spacer may be in the form of a spiral or concentric circles separated by radial limbs, or may be of egg-box construction. Suitable neutron absorbing materials include stainless steel containing boron or gadolinium, hafnium metal or alloys of hafnium. (UK)

  7. Progress toward magnetic confinement of a positron-electron plasma: nearly 100% positron injection efficiency into a dipole trap

    Science.gov (United States)

    Stoneking, Matthew

    2017-10-01

    The hydrogen atom provides the simplest system and in some cases the most precise one for comparing theory and experiment in atomics physics. The field of plasma physics lacks an experimental counterpart, but there are efforts underway to produce a magnetically confined positron-electron plasma that promises to represent the simplest plasma system. The mass symmetry of positron-electron plasma makes it particularly tractable from a theoretical standpoint and many theory papers have been published predicting modified wave and stability properties in these systems. Our approach is to utilize techniques from the non-neutral plasma community to trap and accumulate electrons and positrons prior to mixing in a magnetic trap with good confinement properties. Ultimately we aim to use a levitated superconducting dipole configuration fueled by positrons from a reactor-based positron source and buffer-gas trap. To date we have conducted experiments to characterize and optimize the positron beam and test strategies for injecting positrons into the field of a supported permanent magnet by use of ExB drifts and tailored static and dynamic potentials applied to boundary electrodes and to the magnet itself. Nearly 100% injection efficiency has been achieved under certain conditions and some fraction of the injected positrons are confined for as long as 400 ms. These results are promising for the next step in the project which is to use an inductively energized high Tc superconducting coil to produce the dipole field, initially in a supported configuration, but ultimately levitated using feedback stabilization. Work performed with the support of the German Research Foundation (DFG), JSPS KAKENHI, NIFS Collaboration Research Program, and the UCSD Foundation.

  8. Improved method for Hf separation from silicate rocks for isotopic analysis using Ln-spec resin column

    International Nuclear Information System (INIS)

    Shinjo, Ryuichi; Ginoza, Yuko; Meshesha, Daniel

    2010-01-01

    An improved chemical separation method for Hf isotope ratio measurement using both the thermal ionization mass spectrometer (TIMS) and the multiple collector-inductively coupled plasma-mass spectrometer (MC-ICP-MS) is presented in this paper. In the first column (2.5-ml Eichrom Ln-spec resin), Hf cut was collected with 2M HCl-0.2M HF after washing the major elements, HREE, Ti, Nb, and Zr. For further Hf purification, the second column (1-ml Ln-spec resin) chemistry was conducted in a manner similar to that of the first column. The first column is designed for treatment with a 0.5-g silicate rock sample for TIMS analysis. Thus, because the Hf amount required for MC-ICP-MS analysis is much lesser than that required for TIMS analysis, the column chemistry for MC-ICP-MS analysis can be scaled down, depending on the amount of digested sample. Although there is a need to improve the TIMS technique, the TIMS Hf data obtained for geological reference rocks and Ethiopian flood basalts after the application of the proposed separation methods are consistent, within analytical error, with the previously reported data obtained using the MC-ICP-MS. The advantages of the proposed method include a reduction in the amount of reagents used (hence, a consequent reduction in the blank contribution), reduction in the time required, and a simplified preparation requiring a fewer number of acids. (author)

  9. Post-disruptive plasma loss in the Princeton Beta Experiment (PBX)

    International Nuclear Information System (INIS)

    Jardin, S.C.; DeLucia, J.; Okabayashi, M.; Pomphrey, N.; Reusch, M.; Kaye, S.; Takahashi, H.

    1986-07-01

    The free-boundary, axisymmetric tokamak simulation code TSC is used to model the transport time scale evolution and positional stability of PBX. A disruptive thermal quench will cause the plasma column to move inward in major radius. It is shown that the plasma can then lose axisymmetric stability, causing it to displace exponentially off the midplane, terminating the discharge. We verify the accuracy of the code by modeling several controlled experiments shots in PBX

  10. Plasma heating in multiple-resonance excitation of a plasma in a mirror machine

    Energy Technology Data Exchange (ETDEWEB)

    Bender, A; Siambis, J G [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

    1976-06-01

    By applying 1 kW of microwave power at 2.45 GHz and 1 kW of r.f. power in the frequency range of 4-25 MHz at one end of a mirror machine, where neutral hydrogen gas is injected in a pulsed mode, a plasma density of 2 x 10/sup 11/cm/sup -3/ with an electron temperature of 60 eV and ion temperature of 40 eV is generated. The ion heating mechanism, is, principally, collisional thermalization of the applied r.f. power, via coupling to and excitation of the low frequency resonances of the plasma column, in agreement with the theoretical prediction for the case of high total effective collision frequency for momentum transfer for the electrons.

  11. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  12. Possibility of internal transport barrier formation and electric field bifurcation in LHD plasma

    International Nuclear Information System (INIS)

    Sanuki, H.; Itoh, K.; Yokoyama, M.; Fujisawa, A.; Ida, K.; Toda, S.; Itoh, S.-I.; Yagi, M.; Fukuyama, A.

    1999-05-01

    Theoretical analysis of the electric field bifurcation is made for the LHD plasma. For given shapes of plasma profiles, a region of bifurcation is obtained in a space of the plasma parameters. In this region of plasma parameters, the electric field domain interface is predicted to appear in the plasma column. The reduction of turbulent transport is expected to occur in the vicinity of the interface, inducing a internal transport barrier. Within this simple model, the plasma with internal barriers is predicted to be realized for the parameters of T e (0) ∼ 2 keV and n(0) ≅ 10 18 m -3 . (author)

  13. Performance of RC columns with partial length corrosion

    International Nuclear Information System (INIS)

    Wang Xiaohui; Liang Fayun

    2008-01-01

    Experimental and analytical studies on the load capacity of reinforced concrete (RC) columns with partial length corrosion are presented, where only a fraction of the column length was corroded. Twelve simply supported columns were eccentrically loaded. The primary variables were partial length corrosion in tensile or compressive zone and the corrosion level within this length. The failure of the corroded column occurs in the partial length, mainly developed from or located nearby or merged with the longitudinal corrosion cracks. For RC column with large eccentricity, load capacity of the column is mainly influenced by the partial length corrosion in tensile zone; while for RC column with small eccentricity, load capacity of the column greatly decreases due to the partial length corrosion in compressive zone. The destruction of the longitudinally mechanical integrality of the column in the partial length leads to this great reduction of the load capacity of the RC column

  14. Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

    International Nuclear Information System (INIS)

    Palomares, J.M.; Iordanova, E.; Veldhuizen, E.M. van; Baede, L.; Gamero, A.; Sola, A.; Mullen, J.J.A.M. van der

    2010-01-01

    The axial profiles of the electron density n e and electron temperature T e of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10 18 e 19 m -3 and 1.1 e e and T e down to 8% and 3%, respectively. It is found that n e decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T e does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

  15. A stochastic view on column efficiency.

    Science.gov (United States)

    Gritti, Fabrice

    2018-03-09

    A stochastic model of transcolumn eddy dispersion along packed beds was derived. It was based on the calculation of the mean travel time of a single analyte molecule from one radial position to another. The exchange mechanism between two radial positions was governed by the transverse dispersion of the analyte across the column. The radial velocity distribution was obtained by flow simulations in a focused-ion-beam scanning electron microscopy (FIB-SEM) based 3D reconstruction from a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 particles. Accordingly, the packed bed was divided into three coaxial and uniform zones: (1) a 1.4 particle diameter wide, ordered, and loose packing at the column wall (velocity u w ), (2) an intermediate 130 μm wide, random, and dense packing (velocity u i ), and (3) the bulk packing in the center of the column (velocity u c ). First, the validity of this proposed stochastic model was tested by adjusting the predicted to the observed reduced van Deemter plots of a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 fully porous particles (FPPs). An excellent agreement was found for u i  = 0.93u c , a result fully consistent with the FIB-SEM observation (u i  = 0.95u c ). Next, the model was used to measure u i  = 0.94u c for 2.1 mm × 100 mm column packed with 1.6 μm Cortecs-C 18 superficially porous particles (SPPs). The relative velocity bias across columns packed with SPPs is then barely smaller than that observed in columns packed with FPPs (+6% versus + 7%). u w =1.8u i is measured for a 75 μm × 1 m capillary column packed with 2 μm BEH-C 18 particles. Despite this large wall-to-center velocity bias (+80%), the presence of the thin and ordered wall packing layer has no negative impact on the kinetic performance of capillary columns. Finally, the stochastic model of long-range eddy dispersion explains why analytical (2.1-4.6 mm i.d.) and capillary (columns can all be

  16. Purification of a large molecular weight transglutaminase substrate from liver plasma membranes

    International Nuclear Information System (INIS)

    Slife, C.W.; Morris, G.S.; Tyrrell, D.J.

    1986-01-01

    Transglutaminases are enzymes which catalyze the covalent crosslinking of proteins by forming epsilon(γ-glutamyl)lysine isopeptide linkages. In earlier studies, the authors reported that a large molecular weight protein aggregate in rat liver plasma membranes served as a substrate for a plasma membrane-associated transglutaminase. The enzyme specifically incorporated a lysine analog, [ 3 H]putrescine, into a protein complex which remained at the top of an acrylamide gel upon electrophoresis in SDS and reducing agents. The complex has now been isolated by extracting the plasma membranes with detergent (octylglucoside) resuspending the detergent insoluble residues in 6 M guanidine HCl and chromatographing the residue on a 4% agarose column in 6 M guanidine HCl. Most of the radioactivity is found in the void volume fractions from the column. SDS polyacrylamide gel electrophoresis shows that these fractions contain mostly proteins that do not enter the acrylamide gel. Since this purification procedure is essentially the same as that used to isolate a rat hepatocyte adhesion factor from rat liver plasma membranes it is possible that the large molecular weight transglutaminase substrate and the adhesion factor are contained in the same protein aggregate

  17. SPQR II: A beam-plasma interaction experiment

    Science.gov (United States)

    Bimbot, R.; Della-Negra, S.; Gardès, D.; Rivet, M. F.; Fleurier, C.; Dumax, B.; Hoffman, D. H. H.; Weyrich, K.; Deutsch, C.; Maynard, G.

    1986-01-01

    SPQR II is an interaction experiment designed to probe energy -and charge-exchange of Cn+ ions at 2 MeV/a.m.u., flowing through a fully ionized plasma column of hydrogen with nℓ=1019 e-cm-2 at T=5 eV. One expects a factor of two enhanced stopping over the cold gas case.

  18. Exponential frequency spectrum and Lorentzian pulses in magnetized plasmas

    International Nuclear Information System (INIS)

    Pace, D. C.; Shi, M.; Maggs, J. E.; Morales, G. J.; Carter, T. A.

    2008-01-01

    Two different experiments involving pressure gradients across the confinement magnetic field in a large plasma column are found to exhibit a broadband turbulence that displays an exponential frequency spectrum for frequencies below the ion cyclotron frequency. The exponential feature has been traced to the presence of solitary pulses having a Lorentzian temporal signature. These pulses arise from nonlinear interactions of drift-Alfven waves driven by the pressure gradients. In both experiments the width of the pulses is narrowly distributed resulting in exponential spectra with a single characteristic time scale. The temporal width of the pulses is measured to be a fraction of a period of the drift-Alfven waves. The experiments are performed in the Large Plasma Device (LAPD-U) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] operated by the Basic Plasma Science Facility at the University of California, Los Angeles. One experiment involves a controlled, pure electron temperature gradient associated with a microscopic (6 mm gradient length) hot electron temperature filament created by the injection a small electron beam embedded in the center of a large, cold magnetized plasma. The other experiment is a macroscopic (3.5 cm gradient length) limiter-edge experiment in which a density gradient is established by inserting a metallic plate at the edge of the nominal plasma column of the LAPD-U. The temperature filament experiment permits a detailed study of the transition from coherent to turbulent behavior and the concomitant change from classical to anomalous transport. In the limiter experiment the turbulence sampled is always fully developed. The similarity of the results in the two experiments strongly suggests a universal feature of pressure-gradient driven turbulence in magnetized plasmas that results in nondiffusive cross-field transport. This may explain previous observations in helical confinement devices, research tokamaks, and arc plasmas.

  19. 29 CFR 1926.755 - Column anchorage.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Column anchorage. 1926.755 Section 1926.755 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.755 Column anchorage. (a) General requirements for erection stability. (1) All columns shall be anchored by a minimum of 4 anchor...

  20. Adsorption columns for use in radioimmunoassays

    International Nuclear Information System (INIS)

    1976-01-01

    Adsorption columns are provided which can be utilized in radioimmunoassay systems such as those involving the separation of antibody-antigen complexes from free antigens. The preparation of the columns includes the treatment of retaining substrate material to render it hydrophilic, preparation and degassing of the separation material and loading the column

  1. Modeling of noble gas injection into tokamak plasmas

    International Nuclear Information System (INIS)

    Morozov, D.Kh.; Yurchenko, E.I.; Lukash, V.E.; Baronova, E.O.; Rozhansky, V.A.; Senichenkov, I.Yu.; Veselova, I.Yu.; Schneider, R.

    2005-01-01

    Noble gas injection for mitigation of the disruption in DIII-D is simulated. The simulation of the first two stages is performed: of the neutral gas jet penetration through the background plasmas, and of the thermal quench. In order to simulate the first stage the 1.5-dimensional numerical code LLP with improved radiation model for noble gas is used. It is demonstrated that the jet remains mainly neutral and thus is able to penetrate to the central region of the tokamak in accordance with experimental observations. Plasma cooling at this stage is provided by the energy exchange with the jet. The radiation is relatively small, and the plasma thermal energy is spent mainly on the jet expansion. The magnetic surfaces in contact with the jet are cooled significantly. The cooling front propagates towards the plasma center. The simulations of the plasma column dynamics in the presence of moving jet is performed by means of the free boundary transport modeling DINA code. It has been shown that the cooling front is accompanied by strongly localized 'shark fin-like' perturbation in toroidal current density profile. After few milliseconds the jet (together with the current perturbation) achieves the region where safety factor is slightly higher than unity and a new type of the non-local kink mode develops. The unstable kink perturbation is non-resonant for any magnetic surface, both inside the plasma column, and in the vacuum space. The mode disturbs mainly the core region. The growth time of the 'shark fin-like' mode is higher than the Alfven time by a factor of 100 for DIII-D parameters. Hence, the simulation describes the DIII-D experimental results, at least, qualitatively. (author)

  2. Forecast of TEXT plasma disruptions using soft X-rays as input signal in a neural network

    International Nuclear Information System (INIS)

    Vannucci, A.; Oliveira, K.A.; Tajima, T.; Tajima, Y.J.

    2001-01-01

    A feed-forward neural network is used to forecast major and minor disruptions in TEXT tokamak discharges. Using the experimental data of soft X-ray signals as input data, the neural net is trained with one disruptive plasma discharge, while a different disruptive discharge is used for validation. After proper training, the net works with the same set of weights, it is then used to forecast disruptions in two other different plasma discharges. It is observed that the neural net is capable of predicting the onset of a disruption up to 3.12 ms in advance. From what we observe in the predictive behavior of our network, speculations are made whether the disruption triggering mechanism is associated with an increase in the m=2 magnetic island, that disturbs the central part of the plasma column afterwards, or the initial perturbation has first occurred in the central part of the plasma column and then the m=2 MHD mode is destabilized. (author)

  3. The plasma membrane proteome of germinating barley embryos

    DEFF Research Database (Denmark)

    Hynek, Radovan; Svensson, Birte; Jensen, O.N.

    2009-01-01

    Cereal seed germination involves a complex coordination between different seed tissues. Plasma membranes must play crucial roles in coordination and execution of germination; however, very little is known about seed plasma membrane proteomes due to limited tissue amounts combined...... with amphiphilicity and low abundance of membrane proteins. A fraction enriched in plasma membranes was prepared from embryos dissected from 18 h germinated barley seeds using aqueous two-phase partitioning. Reversed-phase chromatography on C-4 resin performed in micro-spin columns with stepwise elution by 2-propanol...... was used to reduce soluble protein contamination and enrich for hydrophobic proteins. Sixty-one proteins in 14 SDS-PAGE bands were identified by LC-MS/MS and database searches. The identifications provide new insight into the plasma membrane functions in seed germination....

  4. A complex probe for tokamak plasma edge conditions

    International Nuclear Information System (INIS)

    Castro, R.M. de; Silva, R.P. da; Heller, M.V.A.P.; Caldas, I.L.; Nascimento, I.C.; Degasperi, F.T.

    1995-01-01

    The study of the physical processes that occur in the plasma edge of tokamak machines has recently grown due to the evidence that these processes influence those that occur in the center of the plasma column. Experimental studies show the existence of a strong level of fluctuations in the plasma edge. The results of these studies indicate that these fluctuations enhance particle and energy transport and degrade the confinement. In order to investigate these processes in the plasma edge of the TBR-1 Tokamak, a Langmuir probe array, a triple and a set of magnetic probes have been designed and constructed. With this set probes the mean and fluctuation values of the magnetic field were detected and correlated with the fluctuating parameters obtained with the electrostatic probes. (author). 7 refs., 5 figs

  5. DYNAMIC SPECTRAL MAPPING OF INTERSTELLAR PLASMA LENSES

    Energy Technology Data Exchange (ETDEWEB)

    Tuntsov, Artem V.; Walker, Mark A. [Manly Astrophysics, 3/22 Cliff Street, Manly 2095 (Australia); Koopmans, Leon V. E. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, NL-9700 AV Groningen (Netherlands); Bannister, Keith W.; Stevens, Jamie; Johnston, Simon [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia); Reynolds, Cormac; Bignall, Hayley E., E-mail: Artem.Tuntsov@manlyastrophysics.org, E-mail: Mark.Walker@manlyastrophysics.org, E-mail: koopmans@astro.rug.nl [International Centre for Radio Astronomy Research—Curtin University, Perth (Australia)

    2016-02-01

    Compact radio sources sometimes exhibit intervals of large, rapid changes in their flux density, due to lensing by interstellar plasma crossing the line of sight. A novel survey program has made it possible to discover these “Extreme Scattering Events” (ESEs) in real time, resulting in a high-quality dynamic spectrum of an ESE observed in PKS 1939–315. Here we present a method for determining the column-density profile of a plasma lens, given only the dynamic radio spectrum of the lensed source, under the assumption that the lens is either axisymmetric or totally anisotropic. Our technique relies on the known, strong frequency dependence of the plasma refractive index in order to determine how points in the dynamic spectrum map to positions on the lens. We apply our method to high-frequency (4.2–10.8 GHz) data from the Australia Telescope Compact Array of the PKS 1939–315 ESE. The derived electron column-density profiles are very similar for the two geometries we consider, and both yield a good visual match to the data. However, the fit residuals are substantially above the noise level, and deficiencies are evident when we compare the predictions of our model to lower-frequency (1.6–3.1 GHz) data on the same ESE, thus motivating future development of more sophisticated inversion techniques.

  6. NMFS Water Column Sonar Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water column sonar data are an important component of fishery independent surveys, habitat studies and other research. NMFS water column sonar data are archived here.

  7. Joule Heating of Plasma in the Toroidal Tokamak-3 Device; Chauffage du Plasma par Effet Joule, dans l'Installation Torique; Dzhoulev nagrev plazmy na toroidal'noj ustanovke Tokamak-3; Calentamiento de un Plasma por Efeto Joule en la Instalacion Toroidal Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Arcimovich, L. A.; Afrosimov, V. V.; Gladkovskij, I. P.; Mirnov, S. V.; Petrov, M. P.; Strelkov, V. S. [Institut Atomnoj Ehnergii, Im. I.V. Kurchatova, Moskva, SSSR (Russian Federation)

    1966-04-15

    In Tokamak-3, a hydrogen plasma is formed and heated by an annular electric current of 40 to 60 kA. The time of current flow is 20 to 30 ms. The bulk of the experiments were performed with a 25-kOe stabilizing longitudinal magnetic field. The transverse component of the stray magnetic field was compensated for by using special correcting loops. In the course of the discharge there was no appreciable displacement of the centre of the column from the equatorial plane of the torus, and we observed a plasma-column drift ''to the outside'' (increase of the large radius of the loop). This motion can be caused by a change in the radius of the current column, by plasma heating or by the damping of the Foucault currents in the conducting vessel. We succeeded in obtaining a macroscopically stable plasma column in Tokamak-3 under these conditions, but the plasma temperature was lower than should be expected for the case with no anomalous energy losses. The interaction processes between the plasma column and the diaphragm must lead to large energy losses. We succeeded in attenuating this interaction by applying a diaphragm of special shape and by using the property of the column to shift to the outside in the course of the process. The problem of the investigations was to determine various plasma parameters under these conditions, including electron and ion temperatures. To determine the electron temperature from the change of plasma resistance, it is necessary to know the column-radius changes with time, as well as the electric characteristics of the column. By using a computer to solve a set of equations, including the electrical engineering and the equilibrium equations, we can determine the time-dependence of changes in plasma temperature and density and also in the radius and displacement of the plasma, column, making use of experimentally measured time dependencies of plasma current, voltage and magnetic probe and radio interferometer signals. The computed temperature

  8. Investigating the Effect of Column Geometry on Separation Efficiency using 3D Printed Liquid Chromatographic Columns Containing Polymer Monolithic Phases.

    Science.gov (United States)

    Gupta, Vipul; Beirne, Stephen; Nesterenko, Pavel N; Paull, Brett

    2018-01-16

    Effect of column geometry on the liquid chromatographic separations using 3D printed liquid chromatographic columns with in-column polymerized monoliths has been studied. Three different liquid chromatographic columns were designed and 3D printed in titanium as 2D serpentine, 3D spiral, and 3D serpentine columns, of equal length and i.d. Successful in-column thermal polymerization of mechanically stable poly(BuMA-co-EDMA) monoliths was achieved within each design without any significant structural differences between phases. Van Deemter plots indicated higher efficiencies for the 3D serpentine chromatographic columns with higher aspect ratio turns at higher linear velocities and smaller analysis times as compared to their counterpart columns with lower aspect ratio turns. Computational fluid dynamic simulations of a basic monolithic structure indicated 44%, 90%, 100%, and 118% higher flow through narrow channels in the curved monolithic configuration as compared to the straight monolithic configuration at linear velocities of 1, 2.5, 5, and 10 mm s -1 , respectively. Isocratic RPLC separations with the 3D serpentine column resulted in an average 23% and 245% (8 solutes) increase in the number of theoretical plates as compared to the 3D spiral and 2D serpentine columns, respectively. Gradient RPLC separations with the 3D serpentine column resulted in an average 15% and 82% (8 solutes) increase in the peak capacity as compared to the 3D spiral and 2D serpentine columns, respectively. Use of the 3D serpentine column at a higher flow rate, as compared to the 3D spiral column, provided a 58% reduction in the analysis time and 74% increase in the peak capacity for the isocratic separations of the small molecules and the gradient separations of proteins, respectively.

  9. Evaluation of Packed Distillation Columns I - Atmospheric Pressure

    National Research Council Canada - National Science Library

    Reynolds, Thaine

    1951-01-01

    .... Four column-packing combinations of the glass columns and four column-packing combinations of the steel columns were investigated at atmospheric pressure using a test mixture of methylcyclohexane...

  10. Center column design of the PLT

    International Nuclear Information System (INIS)

    Citrolo, J.; Frankenberg, J.

    1975-01-01

    The center column of the PLT machine is a secondary support member for the toroidal field coils. Its purpose is to decrease the bending moment at the nose of the coils. The center column design was to have been a stainless steel casting with the toroidal field coils grouped around the casting at installation, trapping it in place. However, the castings developed cracks during fabrication and were unsuitable for use. Installation of the coils proceeded without the center column. It then became necessary to redesign a center column which would be capable of installation with the toroidal field coils in place. The final design consists of three A-286 forgings. This paper discusses the final center column design and the influence that new knowledge, obtained during the power tests, had on the new design

  11. Nonlinear wavenumber of an electron plasma wave

    International Nuclear Information System (INIS)

    Vidmar, P.J.; Malmberg, J.H.; Starke, T.P.

    1976-01-01

    The wavenumber of a large-amplitude electron plasma wave propagating on a collisionless plasma column is measured. The wavenumber is shifted from that of a small-amplitude wave of the same frequency. This nonlinear wavenumber shift, deltak/subr/, depends on position, frequency, and initial wave amplitude, Phi. The observed spatial oscillations of deltak/subr/ agree qualitatively with recent theories. Experimentally deltak/subr/proportionalk/subi/S (Phi) rootPhi where k/subi/ is the linear Landau damping coefficient, S (Phi) equivalentk/subi/(Phi)/k/subi/, and k/subi/(Phi) is the initial damping coefficient which depends on Phi

  12. A theoretical study of hot plasma spheroids in the presence of low-frequency electromagnetic waves

    Science.gov (United States)

    Ahmadizadeh, Y.; Jazi, B.; Barjesteh, S.

    2016-07-01

    While taking into account thermal motion of electrons, scattering of electromagnetic waves with low frequency from hot plasma spheroids is investigated. In this theoretical research, ions are heavy to respond to electromagnetic fluctuations. The solution of scalar wave equation in spheroidal coordinates for electric potential inside the plasma spheroids are obtained. The variations of resonance frequencies vs. Debye length are studied and consistency between the obtained results in this paper and the results for the well-known plasma objects such as plasma column and spherical plasma have been proved.

  13. Damping Measurements of Plasma Modes

    Science.gov (United States)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.

    2010-11-01

    For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.

  14. Distortion of plasma due to installation of an orifice in helium discharge positive column

    International Nuclear Information System (INIS)

    Moslehi- Fard, M.; Bidadi, H.; Khorram, S.; Sobhanian, S.; Muradov, A.H.; Jallali, H.; Shirin Pour, M.

    2003-01-01

    Complicated potential structure formed at a constriction of positive column of a DC discharge with heated cathode in He at low discharge currents is investigated. According to the potential structure, electrons and ions are accelerated by the electric field and their energy distribution functions acquire multi humped shapes. Additional maximums on distribution function quickly disappear due to collisions and radial losses. The nature of current passing through the potential structure is cleared up on the base of measured distributions. Attempt was made to calculate potential drop in DL tacking into account electron energy distribution variations

  15. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2017-09-01

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  16. Interplay between intrinsic plasma rotation and magnetic island evolution in disruptive discharges

    Energy Technology Data Exchange (ETDEWEB)

    Ronchi, G.; Severo, J. H. F. [Universidade de São Paulo, Instituto de Física (Brazil); Salzedas, F. [Universidade do Porto, Faculdade de Engenharia (Portugal); Galvão, R. M. O., E-mail: rgalvao@if.usp.br; Sanada, E. K. [Universidade de São Paulo, Instituto de Física (Brazil)

    2016-05-15

    The behavior of the intrinsic toroidal rotation of the plasma column during the growth and eventual saturation of m/n = 2/1 magnetic islands, triggered by programmed density rise, has been carefully investigated in disruptive discharges in TCABR. The results show that, as the island starts to grow and rotate at a speed larger than that of the plasma column, the angular frequency of the intrinsic toroidal rotation increases and that of the island decreases, following the expectation of synchronization. As the island saturates at a large size, just before a major disruption, the angular speed of the intrinsic rotation decreases quite rapidly, even though the island keeps still rotating at a reduced speed. This decrease of the toroidal rotation is quite reproducible and can be considered as an indicative of disruption.

  17. Characterization of thermal plasmas by laser light scattering

    International Nuclear Information System (INIS)

    Snyder, S.C.; Lassahn, G.D.; Reynolds, L.D.; Fincke, J.R.

    1993-01-01

    Characterization of an atmospheric pressure free-burning arc discharge and a plasma jet by lineshape analysis of scattered laser light is described. Unlike emission spectroscopy, this technique provides direct measurement of plasma gas temperature, electron temperature and electron density without the assumption of local thermodynamic equilibrium (LTE). Plasma gas velocity can also be determined from the Doppler shift of the scattered laser light. Radial gas temperature, electron temperature and electron density profiles are presented for an atmospheric pressure argon free-burning arc discharge. These results show a significant departure from LTE in the arc column, contradicting results obtained from emission spectroscopy. Radial gas temperature and gas velocity profiles in the exit plane of a subsonic atmospheric pressure argon plasma jet are also presented. In this case, the results show the plasma jet is close to LTE in the center, but not in the fringes. The velocity profile is parabolic

  18. Column-oriented database management systems

    OpenAIRE

    Možina, David

    2013-01-01

    In the following thesis I will present column-oriented database. Among other things, I will answer on a question why there is a need for a column-oriented database. In recent years there have been a lot of attention regarding a column-oriented database, even if the existence of a columnar database management systems dates back in the early seventies of the last century. I will compare both systems for a database management – a colum-oriented database system and a row-oriented database system ...

  19. Experimental observation of current generation by asymmetrical heating of ions in a tokamak plasma

    International Nuclear Information System (INIS)

    Gahl, J.; Ishihara, O.; Wong, K.L.; Kristiansen, M.; Hagler, M.

    1986-01-01

    The first experimental observation of current generation by asymmetrical heating of ions is reported. Ions were asymmetrically heated by a unidirectional fast Alfven wave launched by a slow wave antenna inside a tokamak. Current generation was detected by measuring the asymmetry of the toroidal plasma current with probes at the top and bottom of the toroidal plasma column

  20. Analysis of 26-hydroxycholesterol in plasma by high performance liquid chromatography

    International Nuclear Information System (INIS)

    Kou, I.L.; Holmes, R.P.

    1986-01-01

    A method utilizing HPLC has been developed for the analysis of 26-hydroxycholesterol in plasma. The method involves initially saponifying samples for estimation of the total sterol or extracting samples with acetonitrile to estimate the free sterol. This is followed by a C-18 Sep Pak fractionation of the extracts, further purification on a Nova Pak C-18 HPLC column, and finally by quantitation on a silicic acid HPLC column by measuring the absorbance at 210 nm. Losses of sterol during this multi-step procedure were determined by estimating the recovery of 3 H-26-hydroxycholesterol added to samples before extraction or saponification. The reproducibility of the method was evaluated by repetitive analysis of one plasma sample. The coefficient of variation was 6.8% for six analyses. In agreement with the mass spectrometric determinations of Javitt et al. The authors observed total plasma levels in the range of 140-260 ng/ml in young adult humans, rats, and rabbits. In the plasma of older human patients undergoing coronary by-pass surgery levels ranged from 335-950 ng/ml, suggesting that an increase in the level of 26-hydroxycholesterol is either age-related or related to the development of acute atherosclerosis

  1. Radiotracer Imaging of Sediment Columns

    Science.gov (United States)

    Moses, W. W.; O'Neil, J. P.; Boutchko, R.; Nico, P. S.; Druhan, J. L.; Vandehey, N. T.

    2010-12-01

    Nuclear medical PET and SPECT cameras routinely image radioactivity concentration of gamma ray emitting isotopes (PET - 511 keV; SPECT - 75-300 keV). We have used nuclear medical imaging technology to study contaminant transport in sediment columns. Specifically, we use Tc-99m (T1/2 = 6 h, Eγ = 140 keV) and a SPECT camera to image the bacteria mediated reduction of pertechnetate, [Tc(VII)O4]- + Fe(II) → Tc(IV)O2 + Fe(III). A 45 mL bolus of Tc-99m (32 mCi) labeled sodium pertechnetate was infused into a column (35cm x 10cm Ø) containing uranium-contaminated subsurface sediment from the Rifle, CO site. A flow rate of 1.25 ml/min of artificial groundwater was maintained in the column. Using a GE Millennium VG camera, we imaged the column for 12 hours, acquiring 44 frames. As the microbes in the sediment were inactive, we expected most of the iron to be Fe(III). The images were consistent with this hypothesis, and the Tc-99m pertechnetate acted like a conservative tracer. Virtually no binding of the Tc-99m was observed, and while the bolus of activity propagated fairly uniformly through the column, some inhomogeneity attributed to sediment packing was observed. We expect that after augmentation by acetate, the bacteria will metabolically reduce Fe(III) to Fe(II), leading to significant Tc-99m binding. Imaging sediment columns using nuclear medicine techniques has many attractive features. Trace quantities of the radiolabeled compounds are used (micro- to nano- molar) and the half-lives of many of these tracers are short (Image of Tc-99m distribution in a column containing Rifle sediment at four times.

  2. Thermally stable dexsil-400 glass capillary columns

    International Nuclear Information System (INIS)

    Maskarinec, M.P.; Olerich, G.

    1980-01-01

    The factors affecting efficiency, thermal stability, and reproducibility of Dexsil-400 glass capillary columns for gas chromatography in general, and for polycyclic aromatic hydrocarbons (PAHs) in particular were investigated. Columns were drawn from Kimble KG-6 (soda-lime) glass or Kimox (borosilicate) glass. All silylation was carried out at 200 0 C. Columns were coated according to the static method. Freshly prepared, degassed solutions of Dexsil-400 in pentane or methylene chloride were used. Thermal stability of the Dexsil 400 columns with respect to gas chromatography/mass spectrometry (GC/MS) were tested. Column-to-column variability is a function of each step in the fabrication of the columns. The degree of etching, extent of silylation, and stationary phase film thickness must be carefully controlled. The variability in two Dexsil-400 capillary column prepared by etching, silylation with solution of hexa methyl disilazone (HMDS), and static coating is shown and also indicates the excellent selectivity of Dexsil-400 for the separation of alkylated aromatic compounds. The wide temperature range of Dexsil-400 and the high efficiency of the capillary columns also allow the analysis of complex mixtures with minimal prefractionation. Direct injection of a coal liquefaction product is given. Analysis by GC/MS indicated the presence of parent PAHs, alkylated PAHs, nitrogen and sulfur heterocycles, and their alkylated derivatives. 4 figures

  3. The application of micro-column solid phase extraction techniques for the determination of rare earth elements in actinide containing matrices

    International Nuclear Information System (INIS)

    Carney, K.P.; Cummings, D.G.

    1995-01-01

    The design and characterization of an argon segmented-solid phase extraction system is described. A 200 ul volume micro-column has been constructed for the preconcentration of rare earth elements (REEs) from salt matrices containing uranium. An inductively coupled plasma atomic emission spectrometer has been utilized for simultaneous detection of Sr, Y and the REEs (namely Ce, Eu, La, Nd, Pr, Sm) at levels ranging from 5- to 2000 ppm in LiCl/KCl samples containing U. Preconcentration factors of 100 fold have been demonstrated. The precision, linear dynamic range and column performance of the system will be presented. (author). 5 refs., 5 figs., 3 tabs

  4. Determination of the plasma position for its real-time control in the COMPASS tokamak

    International Nuclear Information System (INIS)

    Janky, F.; Havlicek, J.; Valcarcel, D.; Hron, M.; Horacek, J.; Kudlacek, O.; Panek, R.; Carvalho, B.B.

    2011-01-01

    An efficient horizontal and vertical stabilization of the plasma column position are essential for a reliable tokamak operation. Plasma position is generally determined by plasma current, plasma pressure and external vertical and horizontal magnetic fields. Such fields are generated by poloidal field coils and proper algorithm for the current control have to by applied, namely, in case of fast feedback loops. This paper presents a real-time plasma position reconstruction algorithms developed for the COMPASS tokamak. Further, its implementation in the MARTe (Multithreaded Application Real-Time executor) is described and the first results from test of the algorithm for real-time control of horizontal plasma positions are presented.

  5. Determination of the plasma position for its real-time control in the COMPASS tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Janky, F., E-mail: jankyf@ipp.cas.cz [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague (Czech Republic); Havlicek, J. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague (Czech Republic); Valcarcel, D. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, P1049-001 Lisboa (Portugal); Hron, M.; Horacek, J. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Kudlacek, O. [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Technicka 2, 166 27 Prague (Czech Republic); Panek, R. [Institute of Plasma Physics, AS CR, v.v.i., Association EURATOM/IPP.CR, Za Slovankou 3, 182 00 Prague (Czech Republic); Carvalho, B.B. [Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, P1049-001 Lisboa (Portugal)

    2011-10-15

    An efficient horizontal and vertical stabilization of the plasma column position are essential for a reliable tokamak operation. Plasma position is generally determined by plasma current, plasma pressure and external vertical and horizontal magnetic fields. Such fields are generated by poloidal field coils and proper algorithm for the current control have to by applied, namely, in case of fast feedback loops. This paper presents a real-time plasma position reconstruction algorithms developed for the COMPASS tokamak. Further, its implementation in the MARTe (Multithreaded Application Real-Time executor) is described and the first results from test of the algorithm for real-time control of horizontal plasma positions are presented.

  6. [Determination of acyclovir in mouse plasma and tissues by reversed-phase high performance liquid chromatography].

    Science.gov (United States)

    Xu, Y; Zhou, S W; Tang, J L; Huang, L Q

    2001-11-01

    The aim of this study was to establish an high performance liquid chromatographic method for determining acyclovir (ACV) concentration in mouse plasma and tissues. A solution of 0.25 mL 60 g/L perchloric acid and 0.25 mL acetonitrile was added into 0.2 mL plasma or 0.2 g tissues to precipitate proteins. Following centrifugation, the supernatant obtained was injected into a reversed-phase column. Operating conditions were Hypersil ODS column(250 mm x 4.6 mm i.d., 5 microns), methanol-water-acetic acid(1:99:0.5, volume ratio) solution as mobile phase at a flow rate of 1.5 mL/min, UV detection at 252 nm. The detection limit of ACV concentration in plasma was 20 micrograms/L and that in tissues was 50 ng/g. The standard curves for ACV were linear in plasma and homogenate of tissues (r > 0.99). The precision of the method was good and the recoveries of ACV were higher than 97.5%. So this method is rapid, accurate and convenient for determination of ACV concentrations in plasma and tissues.

  7. Linear theory of plasma Čerenkov masers

    Science.gov (United States)

    Birau, M.

    1996-11-01

    A different theoretical model of Čerenkov instability in the linear amplification regime of plasma Čerenkov masers is developed. The model assumes a cold relativistic annular electron beam propagating through a column of cold dense plasma, the two bodies being immersed in an infinite magnetic guiding field inside a perfect cylindrical waveguide. In order to simplify the calculations, a radial rectangular distribution of plasma and beam density is assumed and only azimuthal symmetric modes are under investigation. The model's difference consists of taking into account the whole plasma and beam electromagnetic structures in the interpretation of the Čerenkov instability. This model leads to alternative results such as the possibility of emission at several frequencies. In addition, the electric field is calculated taking into account its radial phase dependence, so that a map of the field in the interaction region can be presented.

  8. Pinch modes in the SPEED2 plasma focus

    International Nuclear Information System (INIS)

    Kies, W.; Decker, G.; Berntien, U.; Glushkov, D.A.; Sidelnikov, Yu.V.; Koshelev, K.N.; Simanovskij, D.M.; Bobashev, S.V.

    2001-01-01

    Deuterium discharges in the SPEED2 plasma focus (80 kJ, 200 kV, 2 MA, 400 ns) have been found unexpectedly stable within the operational regime as a neutron source. Only at higher filling pressures (above 6 mbar) sometimes m=0 instabilities appeared in the pinch column, especially in discharges of lower efficiency (moderate dynamics and neutron yield). Enhancing the electromagnetic radiation by doping these discharges with heavy gases (e.g. neon, argon) distinctly two pinch modes are produced, the micropinch mode (MPM) or the stable column mode (SCM), with a transition regime where the initial SCM is followed by the MPM. Micropinches are local radiative collapses initiated by m=0 instabilities of low-energy-density pinch plasmas. These instabilities and the successive micropinches can be suppressed by kinetic deuterons produced during dynamical compression of high-energy-density deuterium plasma sheaths. Depending on the relaxation of this fast deuteron component the pinch column can be stabilized for several tens of nanoseconds. While the short-lived (appr.1 ns) micropinches erratically appear as point-like successive flashes along the pinch axis with temperatures about 1 keV and about solid density the reproducible SCM, optimized with respect to the compression ratio, forms a powerful linear radiation source of temperatures and densities similar to the MPM. The SCM needs powerful (fast) drivers in order to use the kinetic ion stabilization, but not necessarily MA currents as available from the SPEED2 driver. This opens the possibility to establish the SCM also in compact experiments like SPEED3 (8 kJ, 80 kV, 0.8 MA, 300 ns) or even SPEED4 (2 kJ, 40 kV 250 kA, 300 ns). (author)

  9. Safety barriers and lighting columns.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1972-01-01

    Problems arising from the sitting of lighting columns on the central reserve are reviewed, and remedial measures such as break-away lighting supports and installation of safety fences on the central reserve on both sides of the lighting columns are examined.

  10. Buffalo plasma fibronectin: a physico-chemical study.

    Science.gov (United States)

    Ahmed, N; Chandra, R; Raj, H G

    2001-12-01

    Plasma fibronectin (FN) of buffalo (Babulis babulis) was purified to apparent homogeneity, using gelatin-Sepharose and heparin-Sepharose affinity columns. It was found to have two subunits of molecular mass 246 kDa and 228 kDa, on SDS-gel. Its immunological cross-reactivity with anti-human plasma FN was confirmed by Western blotting. The amino acid composition was found to be similar to that of human and bovine plasma FNs. Buffalo plasma FN contained 2.23% neutral hexoses and 1.18% sialic acids. No titrable sulfhydryl group could be detected in the absence of denaturant. Reaction with DTNB indicated 3.4 sulfhydryl groups in the molecule, whereas BDC-OH titration gave a value of 3.8 -SH groups in buffalo plasma FN. Stoke's radius, intrinsic viscosity, diffusion coefficient and frictional ratio indicated that buffalo plasma FN did not have a compact globular conformation at physiological pH and ionic strength. Molecular dimensions (average length, 120 nm; molar mass to length ratio, 3950 nm(-1) and mean diameter, 2.4 nm) as revealed by rotary shadowing electron microscopy further supported the extended conformation of buffalo plasma FN. These results show that buffalo plasma FN has similar properties as that of human plasma FN.

  11. Temperature-assisted On-column Solute Focusing: A General Method to Reduce Pre-column Dispersion in Capillary High Performance Liquid Chromatography

    Science.gov (United States)

    Groskreutz, Stephen R.; Weber, Stephen G.

    2014-01-01

    Solvent-based on-column focusing is a powerful and well known approach for reducingthe impact of pre-column dispersion in liquid chromatography. Here we describe an orthogonal temperature-based approach to focusing called temperature-assisted on-column solute focusing (TASF). TASF is founded on the same principles as the more commonly used solvent-based method wherein transient conditions are created thatlead to high solute retention at the column inlet. Combining the low thermal mass of capillary columns and the temperature dependence of solute retentionTASF is used effectivelyto compress injection bands at the head of the column through the transient reduction in column temperature to 5 °C for a defined 7 mm segment of a 6 cm long 150 μm I.D. column. Following the 30 second focusing time, the column temperature is increased rapidly to the separation temperature of 60 °C releasing the focused band of analytes. We developed a model tosimulate TASF separations based on solute retention enthalpies, focusing temperature, focusing time, and column parameters. This model guides the systematic study of the influence of sample injection volume on column performance.All samples have solvent compositions matching the mobile phase. Over the 45 to 1050 nL injection volume range evaluated, TASF reducesthe peak width for all soluteswith k’ greater than or equal to 2.5, relative to controls. Peak widths resulting from injection volumes up to 1.3 times the column fluid volume with TASF are less than 5% larger than peak widths from a 45 nL injection without TASF (0.07 times the column liquid volume). The TASF approach reduced concentration detection limits by a factor of 12.5 relative to a small volume injection for low concentration samples. TASF is orthogonal to the solvent focusing method. Thus, it canbe used where on-column focusing is required, but where implementation of solvent-based focusing is difficult. PMID:24973805

  12. Influence of dust particles on the neon spectral line intensities at the uniform positive column of dc discharge at the space apparatus “Plasma Kristall-4”

    Science.gov (United States)

    Usachev, A. D.; Zobnin, A. V.; Shonenkov, A. V.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Pustyl'nik, M. Y.; Fink, M. A.; Thoma, M. A.; Thomas, H. M.; Padalka, G. I.

    2018-01-01

    Influence of the elongated dust cloud on the intensities of different neon spectral lines in visible and near ir spectral ranges in the uniform positive column has been experimentally investigated using the Russian-European space apparatus “Plasma Kristall-4” (SA PK-4) on board of the International Space Station (ISS). The investigation was performed in the low pressure (0.5 mbar) direct current (dc, 1 mA) gas discharge in neon. Microgravity allowed us to perform experiments with a large dust cloud in the steady-state regime. To avoid the dust cloud drift in the dc electric field a switching dc polarity discharge mode has been applied. During the experiment a dust cloud of 9 mm in diameter in the discharge tube of 30 mm in diameter with the length of about 100 mm has been observed in the steady-state regime. In this regard, the intensities of neon spectral lines corresponding to 3p → 3s electronic transitions have increased by a factor of 1.4 times, while the intensities of neon spectral lines corresponding to 3d → 3p electronic transitions have increased by a factor of 1.6 times. The observed phenomenon is explained on the basis of the Schottky approach by a self-consistent rising dc electric field in the dusty plasma cloud resulting in an increase of the electron temperature.

  13. Identification and control of plasma vertical position using neural network in Damavand tokamak

    International Nuclear Information System (INIS)

    Rasouli, H.; Rasouli, C.; Koohi, A.

    2013-01-01

    In this work, a nonlinear model is introduced to determine the vertical position of the plasma column in Damavand tokamak. Using this model as a simulator, a nonlinear neural network controller has been designed. In the first stage, the electronic drive and sensory circuits of Damavand tokamak are modified. These circuits can control the vertical position of the plasma column inside the vacuum vessel. Since the vertical position of plasma is an unstable parameter, a direct closed loop system identification algorithm is performed. In the second stage, a nonlinear model is identified for plasma vertical position, based on the multilayer perceptron (MLP) neural network (NN) structure. Estimation of simulator parameters has been performed by back-propagation error algorithm using Levenberg–Marquardt gradient descent optimization technique. The model is verified through simulation of the whole closed loop system using both simulator and actual plant in similar conditions. As the final stage, a MLP neural network controller is designed for simulator model. In the last step, online training is performed to tune the controller parameters. Simulation results justify using of the NN controller for the actual plant.

  14. Identification and control of plasma vertical position using neural network in Damavand tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Rasouli, H. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Advanced Process Automation and Control (APAC) Research Group, Faculty of Electrical Engineering, K.N. Toosi University of Technology, P.O. Box 16315-1355, Tehran (Iran, Islamic Republic of); Rasouli, C.; Koohi, A. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of)

    2013-02-15

    In this work, a nonlinear model is introduced to determine the vertical position of the plasma column in Damavand tokamak. Using this model as a simulator, a nonlinear neural network controller has been designed. In the first stage, the electronic drive and sensory circuits of Damavand tokamak are modified. These circuits can control the vertical position of the plasma column inside the vacuum vessel. Since the vertical position of plasma is an unstable parameter, a direct closed loop system identification algorithm is performed. In the second stage, a nonlinear model is identified for plasma vertical position, based on the multilayer perceptron (MLP) neural network (NN) structure. Estimation of simulator parameters has been performed by back-propagation error algorithm using Levenberg-Marquardt gradient descent optimization technique. The model is verified through simulation of the whole closed loop system using both simulator and actual plant in similar conditions. As the final stage, a MLP neural network controller is designed for simulator model. In the last step, online training is performed to tune the controller parameters. Simulation results justify using of the NN controller for the actual plant.

  15. Heat Transfer Analysis for a Fixed CST Column

    International Nuclear Information System (INIS)

    Lee, S.Y.

    2004-01-01

    In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for several alternate column sizes, heat loads of the packed column, engineered cooling systems, and various ambient conditions at the exterior wall of the column have been performed under the reference conditions of the CST-salt solution to assess the impact of those parameters on the peak temperatures of the packed column for a given transient time. The results indicate that a water-coolant pipe at the center of the CST column filled with salt solution is the most effective one among the potential design parameters related to the thermal energy dissipation of decay heat load. It is noted that the cooling mechanism at the wall boundary of the column has significant

  16. NON-LINEAR ANALYSIS OF AN EXPERIMENTAL JOINT OF COLUMN AND BEAMS OF ARMED CONCRETE-STEEL COLUMN FOR FRAME

    Directory of Open Access Journals (Sweden)

    Nelson López

    2017-12-01

    Full Text Available In this research, the nonlinear behavior of a real-scale experimental joint (node is studied, consisting of three reinforced concrete elements, one column and two beams joined to a structural steel column at the upper level. In the numerical analysis the model of the union was analyzed in the inelastic range, this model was elaborated with the finite element program based on fibers, SeismoStruct to analyze as a function of time, the traction and compression efforts in the confined area and not confined area of the concrete column and in the longitudinal reinforcement steel, as well as verification of the design of the base plate that joins the two columns. The results showed that tensile stresses in the unconfined zone surpassed the concrete breaking point, with cracking occurring just below the lower edge of the beams; in the confined area the traction efforts were much lower, with cracks occurring later than in the non-confined area. The concrete column-steel column joint behaved as a rigid node, so the elastic design was consistent with the calculation methodology of base plates for steel columns.

  17. Microscale depletion of high abundance proteins in human biofluids using IgY14 immunoaffinity resin: analysis of human plasma and cerebrospinal fluid.

    Science.gov (United States)

    Hyung, Seok-Won; Piehowski, Paul D; Moore, Ronald J; Orton, Daniel J; Schepmoes, Athena A; Clauss, Therese R; Chu, Rosalie K; Fillmore, Thomas L; Brewer, Heather; Liu, Tao; Zhao, Rui; Smith, Richard D

    2014-11-01

    Removal of highly abundant proteins in plasma is often carried out using immunoaffinity depletion to extend the dynamic range of measurements to lower abundance species. While commercial depletion columns are available for this purpose, they generally are not applicable to limited sample quantities (depletion media can be prohibitive for larger-scale studies. Modern LC-MS instrumentation provides the sensitivity necessary to scale-down depletion methods with minimal sacrifice to proteome coverage, which makes smaller volume depletion columns desirable for maximizing sample recovery when samples are limited, as well as for reducing the expense of large-scale studies. We characterized the performance of a 346 μL column volume microscale depletion system, using four different flow rates to determine the most effective depletion conditions for ∼6-μL injections of human plasma proteins and then evaluated depletion reproducibility at the optimum flow rate condition. Depletion of plasma using a commercial 10-mL depletion column served as the control. Results showed depletion efficiency of the microscale column increased as flow rate decreased, and that our microdepletion was reproducible. In an initial application, a 600-μL sample of human cerebrospinal fluid (CSF) pooled from multiple sclerosis patients was depleted and then analyzed using reversed phase liquid chromatography-mass spectrometry to demonstrate the utility of the system for this important biofluid where sample quantities are more commonly limited.

  18. Elongated dust clouds in a uniform DC positive column of low pressure gas discharge

    International Nuclear Information System (INIS)

    Usachev, A D; Zobnin, A V; Petrov, O F; Fortov, V E; Thoma, M H; Pustylnik, M Y; Fink, M A; Morfill, G E

    2016-01-01

    Experimental investigations of the formation of elongated dust clouds and their influence on the plasma glow intensity of the uniform direct current (DC) positive column (PC) have been performed under microgravity conditions. For the axial stabilization of the dust cloud position a polarity switching DC gas discharge with a switching frequency of 250 Hz was used. During the experiment, a spontaneous division of one elongated dust cloud into two smaller steady state dust clouds has been observed. Quantitative data on the dust cloud shape, size and dust number density distribution were obtained. Axial and radial distributions of plasma emission within the 585.2 nm and 703.2 nm neon spectral lines were measured over the whole discharge volume. It has been found that both spectral line intensities at the dust cloud region grew 1.7 times with respect to the undisturbed positive column region; in this the 585.2 nm line intensity increased by 10% compared to the 703.2 nm line intensity. For a semi-quantitative explanation of the observed phenomena the Schottky approach based on the equation of diffusion was used. The model reasonably explains the observed glow enhancement as an increasing of the ionization rate in the discharge with dust cloud, which compensates ion-electron recombination on the dust grain surfaces. In this, the ionization rate increases due to the growing of the DC axial electric field, and the glow grows directly proportional to the electric field. It is shown that the fundamental condition of the radial stability of the dusty plasma cloud is equal to the ionization and recombination rates within the cloud volume that is possible only when the electron density is constant and the radial electric field is absent within the dust cloud. (paper)

  19. Fabrication of a micrometer Ni–Cu alloy column coupled with a Cu micro-column for thermal measurement

    International Nuclear Information System (INIS)

    Lin, J C; Chang, T K; Yang, J H; Jeng, J H; Lee, D L; Jiang, S B

    2009-01-01

    Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni–Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision

  20. Behavior of reinforced concrete columns strenghtened by partial jacketing

    Directory of Open Access Journals (Sweden)

    D. B. FERREIRA

    Full Text Available This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column e PR (reference column. The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.

  1. Development and validation of a high-performance liquid chromatography method for determination of lisinopril in human plasma by magnetic solid-phase extraction and pre-column derivatization.

    Science.gov (United States)

    Rastkari, Noushin; Ahmadkhaniha, Reza

    2018-03-01

    A sensitive, reliable and simple HPLC method was developed for the determination of lisinopril in human plasma. The method consists of extraction and clean-up steps based on magnetic solid-phase extraction and pre-column derivatization with a fluorescent reagent. The mobile phase consisted of a mixture of methanol-sodium dihydrogen phosphate (pH 3.0; 0.005 m; 75:25, v/v). The flow rate was set at 0.7 mL/min. Fluorescence detection was performed at 470nm excitation and 530nm emission wavelengths. Total chromatography run time was 5 min. The average extraction recovery of lisinopril and fluvoxamine (internal standard) was ≥82.8%. The limits of detection and quantification were determined as 1 and 3 ng/mL respectively. The method exhibited a linear calibration line over the concentration range of 3-1000 ng/mL with coefficient of determination (r 2 ) of ≥0.98. The within-run and between-run precisions were satisfactory with values of CV of 1.8-12.8% (accuracy from 99.2 to 94.7%) and 2.4-13.7% (accuracy from 99.5 to 92.2%), respectively. These developments led to considerable improvement in method sensitivity and reliability. The method was validated according to the US Food and Drug Administration guidelines. Therefore, it can be considered as a suitable method for determination of lisinopril in plasma samples. Copyright © 2017 John Wiley & Sons, Ltd.

  2. Recent advances in column switching sample preparation in bioanalysis.

    Science.gov (United States)

    Kataoka, Hiroyuki; Saito, Keita

    2012-04-01

    Column switching techniques, using two or more stationary phase columns, are useful for trace enrichment and online automated sample preparation. Target fractions from the first column are transferred online to a second column with different properties for further separation. Column switching techniques can be used to determine the analytes in a complex matrix by direct sample injection or by simple sample treatment. Online column switching sample preparation is usually performed in combination with HPLC or capillary electrophoresis. SPE or turbulent flow chromatography using a cartridge column and in-tube solid-phase microextraction using a capillary column have been developed for convenient column switching sample preparation. Furthermore, various micro-/nano-sample preparation devices using new polymer-coating materials have been developed to improve extraction efficiency. This review describes current developments and future trends in novel column switching sample preparation in bioanalysis, focusing on innovative column switching techniques using new extraction devices and materials.

  3. The determination of pentobarbital and other barbiturates in blood plasma by gas—liquid chromatography with on-column and pre-column butylation

    NARCIS (Netherlands)

    Hulshoff, A.; Houwen, O.A.G.J. van der; Barends, D.M.; Kostenbauder, H.B.

    1979-01-01

    Two g.l.c. methods for the determination of pentobarbital and other barbiturates are reported. In the first method the plasma samples are extracted with toluene; the toluene layer is back-extracted with a small volume of a tetrabutylammonium hydroxide solution of which an aliquot is injected into

  4. Chromatographic properties PLOT multicapillary columns.

    Science.gov (United States)

    Nikolaeva, O A; Patrushev, Y V; Sidelnikov, V N

    2017-03-10

    Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD). These MCCs have the efficiency of 4000-10000 theoretical plates per meter (TP/m) and at a column length of 25-30cm can separate within 10-20s multicomponent mixtures of substances belonging to different classes of chemical compounds. The sample amount not overloading the column is 0.03-1μg and depends on the features of a porous layer. Examples of separations on some of the studied columns are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Advection of long lived density blobs in the turbulent state of a simple magnetized torus plasma

    International Nuclear Information System (INIS)

    Barni, R; Riccardi, C

    2009-01-01

    The turbulent regime of a simple magnetized toroidal plasma column has been studied in the plasma device Thorello. The detection and the study of the spatio-temporal evolution of structures have been performed by means of conditional sampling techniques as well as other statistical tools. As a result the evidence of plasma blob formation and expulsion from the edge of the main plasma column has been obtained. The relation between structure phenomenology and statistical characteristics of the turbulent regime has been investigated. The motion of the density structures in the edge region of our device does not look ballistic but rather driven by the overall potential profile established in the turbulent state. Potential fluctuations are strongly anti-correlated with density structures, located in the same position and somewhat more extended. They provide a shallow potential well with a flat bottom and quite sharp edges surrounding and co-moving with the blobs. Blob lifetime exceeds the residence time associated with the overall E x B drift field. Then such persistent structures provide a means for a net convection of the charged particles to the limiter, across the magnetic field and beyond the edge region of the plasma.

  6. Routine plasma analysis for 2-[18F]fluorotyrosine by SAX-cartridges

    International Nuclear Information System (INIS)

    Kling, P.; Coenen, H.H.; Stoecklin, G.

    1990-01-01

    There is a great necessity for simple, reliable, and fast methods of plasma analysis. While HPLC is generally the most effective method, it is rather time consuming and expensive in a routine setting with numerous plasma samples. The authors have developed a new method for determination of the amino acid analogue 2-[ 18 F]fluorotyrosine using SAX columns (Adsorbex R SAX, 400 mg, Merck). The results obtained agree within 5% with those determined by reverse phase HPLC

  7. Guiding of laser pulses in plasma waveguides created by linearly-polarized femtosecond laser pulses

    OpenAIRE

    Lemos, N.; Cardoso, L.; Geada, J.; Figueira, G.; Albert, F.; Dias, J. M.

    2018-01-01

    We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a wav...

  8. Post-column mobile phase adjustment: a strategy to eliminate the contradiction between liquid chromatography and mass spectrometry in the determination of flavonoids in rat plasma.

    Science.gov (United States)

    Zheng, Shirui; Ma, Zhiyuan; Han, Haixia; Ye, Jianfeng; Wang, Ruwei; Cai, Sheng; Zhou, Hui; Yu, Lushan; Zeng, Su; Jiang, Huidi

    2014-07-01

    Flavonoids are a group of important naturally occurring polyphenolic compounds with a wide range of biological effects. In this study, a sensitive liquid chromatography tandem mass spectrometry method was developed to simultaneously determine multiple active flavonoids, including quercetin (Que), kaempferol (Kae), apigenin (Api), isorhamnetin (Iso), luteolin (Lut), and naringenin (Nar), in rat plasma. To achieve a satisfied peak shape and LC separation, formic acid with the concentration between 0.05 and 0.2%, or in some case 5%, was generally used to acidify the LC mobile phase in reported studies. Here we found that even 0.05% formic acid could lead to strong mass signal suppression, and the absence of formic acid could reverse the signal suppression but cause serious peak tailing. There is an irreconcilable contradiction between liquid chromatography (LC) and mass spectrometry (MS). In order to simultaneously satisfy LC and MS, LC mobile phase with 0.00075% formic acid and post column mobile phase adjustment with 0.0677% ammonium solution in isopropanol were applied. Compared with the conventional method with mobile phase containing 0.05% formic acid, the mass signal response of Que, Kae, Api, Iso, Lut, Nar, and Oka increased 26.2, 18.6, 13.6, 23.5, 17.5, 15.6 and 15.4 fold, respectively. In addition, the post column mobile phase addition exhibited the better peak shape for the reduction of analytes longitudinal diffusion. The method has been fully validated according to FDA guidelines within the linear range between 0.328 ng mL⁻¹ and 168 ng mL⁻¹, and successfully applied to a pilot pharmacokinetic study of rats after administering 5.43 g kg⁻¹ Pollen of Brassica campestris. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. PRTR ion exchange vault column sampling

    International Nuclear Information System (INIS)

    Cornwell, B.C.

    1995-01-01

    This report documents ion exchange column sampling and Non Destructive Assay (NDA) results from activities in 1994, for the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. The objective was to obtain sufficient information to prepare disposal documentation for the ion exchange columns found in the PRTR Ion exchange vault. This activity also allowed for the monitoring of the liquid level in the lower vault. The sampling activity contained five separate activities: (1) Sampling an ion exchange column and analyzing the ion exchange media for purpose of waste disposal; (2) Gamma and neutron NDA testing on ion exchange columns located in the upper vault; (3) Lower vault liquid level measurement; (4) Radiological survey of the upper vault; and (5) Secure the vault pending waste disposal

  10. HPLC Method for Determination of Rifaximin in Human Plasma ...

    African Journals Online (AJOL)

    The present study was aimed at developing a simple, sensitive, and specific liquid chromatography–tandem mass spectrometry method for the quantification of rifaximin in human plasma using rifaximin D6 as internal standard. Chromatographic separation was performed on Zorbax SB C18, 4.6 x 75 mm, 3.5 μm column with ...

  11. Observation of refraction and convergence of ion acoustic waves in a plasma with a temperature gradient

    International Nuclear Information System (INIS)

    Nishida, Y.; Hirose, A.

    1977-01-01

    The refraction and convergence of ion acoustic waves are experimentally investigated in a magnetized plasma with an electron temperature gradient. When ion acoustic waves are launched parallel to the field lines the waves converge toward the interior of the plasma column where the electron temperature is lower, in good agreement with theoretical prediction. Wave interference is also observed. (author)

  12. Tokamak plasma boundary layer model

    International Nuclear Information System (INIS)

    Volkov, T.F.; Kirillov, V.D.

    1983-01-01

    A model has been developed for the limiter layer and for the boundary region of the plasma column in a tokamak to facilitate analytic calculations of the thickness of the limiter layers, the profiles and boundary values of the temperature and the density under various conditions, and the difference between the electron and ion temperatures. This model can also be used to analyze the recycling of neutrals, the energy and particle losses to the wall and the limiter, and other characteristics

  13. Field Applications of Gamma Column Scanning Technology

    International Nuclear Information System (INIS)

    Aquino, Denis D.; Mallilin, Janice P.; Nuñez, Ivy Angelica A.; Bulos, Adelina DM.

    2015-01-01

    The Isotope Techniques Section (ITS) under the Nuclear Service Division (NSD) of the Philippine Nuclear Research Institute (PNRI) conducts services, research and development on radioisotope and sealed source application in the industry. This aims to benefit the manufacturing industries such as petroleum, petrochemical, chemical, energy, waste, column treatment plant, etc. through on line inspection and troubleshooting of a process vessel, column or pipe that could optimize the process operation and increase production efficiency. One of the most common sealed source techniques for industrial applications is the gamma column scanning technology. Gamma column scanning technology is an established technique for inspection, analysis and diagnosis of industrial columns for process optimization, solving operational malfunctions and management of resources. It is a convenient non-intrusive, cost effective and cost-efficient technique to examine inner details of an industrial process vessel such as a distillation column while it is in operation. The Philippine Nuclear Research Institute (PNRI) recognize the importance and benefits of this technology and has implemented activities to make gamma column scanning locally available to benefit the Philippine industries. Continuous effort for capacity building is being pursued thru the implementation of in-house and on-the-job training abroad and upgrading of equipment. (author)

  14. Pulsed, atmospheric pressure plasma source for emission spectrometry

    Science.gov (United States)

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2004-05-11

    A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

  15. Three-Dimensional Simulation of Plasma Deformation During Contact Opening in a Circuit Breaker, Including the Analysis of Kink Instability and Sausage Instability

    International Nuclear Information System (INIS)

    Abbasi, Vahid; Gholami, Ahmad; Niayesh, Kaveh

    2012-01-01

    A three-dimensional (3-D) transient model has been developed to investigate plasma deformation driven by a magnetic field and its influence on arc stability in a circuit breaker. The 3-D distribution of electric current density is obtained from a current continuity equation along with the generalized Ohm's law; while the magnetic field induced by the current flowing through the arc column is calculated by the magnetic vector potential equation. When gas interacts with an arc column, fundamental factors, such as Ampere's law, Ohm's law, the turbulence model, transport equations of mass, momentum and energy of plasma flow, have to be coupled for analyzing the phenomenon. The coupled interactions between arc and plasma flow are described in the framework of time-dependent magnetohydrodynamic (MHD) equations in conjunction with a K-ε turbulence model. Simulations have been focused on sausage and kink instabilities in plasma (these phenomena are related to pinch effects and electromagnetic fields). The 3-D simulation reveals the relation between plasma deformation and instability phenomena, which affect arc stability during circuit breaker operation. Plasma deformation is the consequence of coupled interactions between the electromagnetic force and plasma flow described in simulations. (plasma technology)

  16. Thomson scattering on argon surfatron plasmas at intermediate pressures: Axial profiles of the electron temperature and electron density

    Energy Technology Data Exchange (ETDEWEB)

    Palomares, J.M., E-mail: f02palij@gmail.co [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Iordanova, E.; Veldhuizen, E.M. van; Baede, L. [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Gamero, A.; Sola, A. [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain); Mullen, J.J.A.M. van der, E-mail: j.j.a.m.v.d.Mullen@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)

    2010-03-15

    The axial profiles of the electron density n{sub e} and electron temperature T{sub e} of argon surfatron plasmas in the pressure range of 6-20 mbar and microwave power between 32 and 82 W have been determined using Thomson Scattering of laser irradiation at 532 nm. For the electron density and temperature we found values in the ranges 5 x 10{sup 18} < n{sub e} < 8 x 10{sup 19} m{sup -3} and 1.1 < T{sub e} < 2.0 eV. Due to several improvements of the setup we could reduce the errors of n{sub e} and T{sub e} down to 8% and 3%, respectively. It is found that n{sub e} decreases in the direction of the wave propagation with a slope that is nearly constant. The slope depends on the pressure but not on the power. Just as predicted by theories we see that increasing the power leads to longer plasma columns. However, the plasmas are shorter than what is predicted by theories based on the assumption that for the plasma-wave interaction electron-atom collisions are of minor importance (the so-called collisionless regime). The plasma vanishes long before the critical value of the electron density is reached. In contrast to what is predicted by the positive column model it is found that T{sub e} does not stay constant along the column, but monotonically increases with the distance from the microwave launcher. Increases of more than 50% over 30 cm were found.

  17. MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, I. A., E-mail: Ivanov@inp.nsk.su; Arzhannikov, A. V.; Burmasov, V. S.; Popov, S. S.; Postupaev, V. V.; Sklyarov, V. F.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Burdakov, A. V.; Sorokina, N. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation); Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Mekler, K. I.; Rovenskikh, A. F.; Trunev, Yu. A. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Kurkuchekov, V. V.; Kuznetsov, S. A. [Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Polosatkin, S. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation)

    2015-12-15

    There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70–110 keV for the electron energy, 1–10 MW for the beam power and 30–300 μs for its duration. The spectrum was measured in 75–230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.

  18. Distinct Iron-binding Ligands in the Upper Water Column at Station ALOHA

    Science.gov (United States)

    Bundy, R.; Boiteau, R.; Repeta, D.

    2016-02-01

    The distribution and chemical properties of iron-binding organic ligands at station ALOHA were examined using a combination of solid phase extraction (SPE) followed by high pressure liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS). HPLC-ICPMS ligand measurements were complemented by competitive ligand exchange adsorptive cathodic stripping voltammetry (CLE-ACSV) analysis using salicylaldoxime as the added ligand. By HPLC-ICPMS, we find enhanced concentrations of distinct naturally-occurring polar iron-binding ligands present at the surface and in the chlorophyll maximum. Lower concentrations were found in the subsurface, where a suite of non-polar ligands was detected. Siderophores were present at the deepest depths sampled at station ALOHA, down to 400m. Incubation studies provided evidence for the production of iron-binding ligands associated with nutrient amended phytoplankton growth in surface waters, and as a result of microbial particle remineralization in the subsurface water column. Ligands classes identified via SPE were then compared to CLE-ACSV ligand measurements, as well as the conditional stability constants measured from model polar and non-polar siderophores, yielding insight to the sources of iron-binding ligands throughout the water column at station ALOHA.

  19. Streaming instabilities of a non-neutral plasma with turning points

    International Nuclear Information System (INIS)

    Turner, L.; Finn, J.M.

    1995-01-01

    Streaming instabilities of a reflexing beam in a slab model of a beam Penning trap or an inertial electrostatic confinement device are studied. Particles may have turning points that may be between the walls. Linear theory is developed for the case in which the self-field cancels the external potential. If the electric field perturbation is odd about the center, these two-stream modes couple the slow waves on the two beams. Even modes consist of two classes: a class of two-stream modes and another class of complex-frequency modes, coupling the slow and fast waves on the same beam. The latter are unstable over a larger range than the two-stream modes. Thermal spread is stabilizing only when the thermal and streaming velocities are comparable. Numerical results for the general class of equilibria show both two-stream-like modes and oscillating modes

  20. Quantification of low molecular weight selenium metabolites in human plasma after treatment with selenite in pharmacological doses by LC-ICP-MS

    DEFF Research Database (Denmark)

    Flouda, Konstantina; Dersch, Julie Maria; Gabel-Jensen, Charlotte

    2016-01-01

    The paper presents an analytical method for quantification of low molecular weight (LMW) selenium compounds in human plasma based on liquid chromatography inductively coupled plasma mass spectrometry (LC-ICP-MS) and post column isotope dilution-based quantification. Prior to analysis, samples were...

  1. Measurement of gravitational acceleration of antimatter

    International Nuclear Information System (INIS)

    Rouhani, S.

    1989-12-01

    The minute yet effective impact of gravitational potential in the central region of a long tube magnetic container of non-neutral plasmas can be utilized for the measurement of the gravitational acceleration of antimatter particles. The slight change in distribution of plasma particles along the gravitational field affects the internal electric field of the plasma, which in turn affects the frequency of the magnetron motion of its particles. Thus, a rather straightforward relation is established between the gravitational acceleration of the particles and their magnetron frequencies, which is measurable directly, determining the value of the gravitational acceleration. (author). 7 refs, 3 figs

  2. Picobubble enhanced column flotation of fine coal

    Energy Technology Data Exchange (ETDEWEB)

    Tao, D.; Yu, S.; Parekh, B.K. [University of Kentucky, Lexington, KY (United States). Mining Engineering

    2006-07-01

    The purpose is to study the effectiveness of picobubbles in the column flotation of -28 mesh fine coal particles. A flotation column with a picobubble generator was developed and tested for enhancing the recovery of ultrafine coal particles. The picobubble generator was designed using the hydrodynamic cavitation principle. A metallurgical and a steam coal were tested in the apparatus. The results show that the use of picobubbles in a 2in. flotation column increased the recovery of fine coal by 10 to 30%. The recovery rate varied with feed rate, collector dosage, and other column conditions. 40 refs., 8 figs., 2 tabs.

  3. A rapid and validated HPLC method to quantify sphingosine 1-phosphate in human plasma using solid-phase extraction followed by derivatization with fluorescence detection

    NARCIS (Netherlands)

    Butter, Jan J.; Koopmans, Richard P.; Michel, Martin C.

    2005-01-01

    We describe the development and validation of analytical methodology for the determination of sphingosine 1-phosphate (S1P) in plasma. It uses solid-phase extraction (SPE) followed by an automated reversed-phase gradient HPLC column-switching system with a pre-column derivatization with

  4. Pinches and micropinches in the SPEED 2 plasma focus

    Energy Technology Data Exchange (ETDEWEB)

    Roewekamp, P; Decker, G; Kies, W; Lucas, B; Schmitz, F; Ziethen, G [Heinrich-Heine-Univ., Duesseldorf (Germany). Institut fuer Experimentalphysik; Simanovskij, D M; Bobashev, S V [Russian Academy of Sciences, St. Petersburg (Russian Federation). A.F. Ioffe Physico-Technical Inst.

    1997-12-31

    The discharges in the SPEED 2 Plasma Focus as well as other pinch plasmas generated in a plasma focus configuration exhibit two different modes. The micropinch mode is experimentally investigated in detail and well theoretically modelled. Therefore its characteristics e.g. temperature, density, life time and energy output are well known. Nevertheless the micropinches appear very erratic in space and time and their optimization and application is rather difficult. In contrast to this the column mode is not equally well understood yet. Its remarkable features are the unexpectedly high stability (also if the critical current for radiative collapse is exceeded) and its reproducibility, which are important for applications in soft x-ray microscopy or lithography. (J.U.). 6 figs., 9 refs.

  5. Experimental Study of RailPAc Plasma Actuator for High-Authority Aerodynamic Flow Control in One Atmosphere

    Science.gov (United States)

    Gray, Miles; Choi, Young-Joon; Raja, Laxminarayan; Sirohi, Jayant

    2014-10-01

    Dielectric barrier discharge (DBD) actuators, a type of electrohydrodynamic (EHD) plasma actuator, have generated considerable interest in recent years. However, theoretical performance limitations hinder their application for high speed flows. Magnetohydrodynamic (MHD) plasma actuators with higher control authority circumvent these limitations, offering an excellent alternative. The rail plasma actuator (RailPAc) is an MHD actuator which uses Lorentz force to impart momentum to the surrounding air. RailPAc functions by generating a fast propagating arc column between two rail electrodes that accelerate the arc through J × B forces in a self-induced B-field. The arc column drags the surrounding air to induce aerodynamic flow motion. Our study of the RailPAc will include a description of the transient arc discharge structure through high-speed imaging and a description of the arc composition and temperature through time-resolved emission spectroscopy. Time-resolved force measurements quantify momentum transfer from the arc to the surrounding air and provides a direct measure of the actuator control authority.

  6. Harmonic surface wave propagation in plasma

    International Nuclear Information System (INIS)

    Shivarova, A.; Stoychev, T.

    1980-01-01

    Second order harmonic surface waves generated by one fundamental high-frequency surface wave are investigated experimentally in gas discharge plasma. Two types of harmonic waves of equal frequency, associated with the linear dispersion relation and the synchronism conditions relatively propagate. The experimental conditions and the different space damping rates of the waves ensure the existence of different spatial regions (consecutively arranged along the plasma column) of a dominant propagation of each one of these two waves. Experimental data are obtained both for the wavenumbers and the space damping rates by relatively precise methods for wave investigations such as the methods of time-space diagrams and of phase shift measurements. The results are explained by the theoretical model for nonlinear mixing of dispersive waves. (author)

  7. Exploring the effect of mesopore size reduction on the column performance of silica-based open tubular capillary columns.

    Science.gov (United States)

    Hara, Takeshi; Futagami, Shunta; De Malsche, Wim; Baron, Gino V; Desmet, Gert

    2018-06-01

    We report on a modification in the hydrothermal treatment process of monolithic silica layers used in porous-layered open tubular (PLOT) columns. Lowering the temperature from the customary 95 °C to 80 °C, the size of the mesopores reduced by approximately about 35% from 12-13.5 nm to 7.5-9 nm, while the specific pore volume essentially remains unaltered. This led to an increase of the specific surface area (SA) of about 40%, quasi-independent of the porous layer thickness. The increased surface area provided a corresponding increase in retention, somewhat more (48%) than expected based on the increase in SA for the thin layer columns, and somewhat less than expected (34%) for the thick layer columns. The recipes were applied in 5 μm i.d.-capillaries with a length of 60 cm. Efficiencies under retained conditions amounted up to N = 137,000 for the PLOT column with a layer thickness (d f ) of 300 nm and to N = 109,000 for the PLOT column with d f  = 550 nm. Working under conditions of similar retention, the narrow pore/high SA columns produced with the new 80 °C recipe generated the same number of theoretical plates as the wide pore size/low SA columns produced with the 95 °C recipe. This shows the 80 °C-hydrothermal treatment process allows for an increase in the phase ratio of the PLOT columns without affecting their intrinsic mass transfer properties and separation kinetics. This is further corroborated by the fact that the plate height curves generated with the new and former recipe can both be well-fitted with the Golay-Aris equation without having to change the intra-layer diffusion coefficient. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Plasma focus neutron anisotropy measurements and influence of a deuteron beam obstacle

    Energy Technology Data Exchange (ETDEWEB)

    Talebitaher, A. [Physics Department, University of Regina, Saskatchewan, Canada S4S 0A2 (Canada); Springham, S.V., E-mail: stuart.springham@nie.edu.sg [Natural Sciences and Science Education, National Institute of Education, 637616 (Singapore); Rawat, R.S.; Lee, P. [Natural Sciences and Science Education, National Institute of Education, 637616 (Singapore)

    2017-03-11

    The deuterium-deuterium (DD) fusion neutron yield and anisotropy were measured on a shot-to-shot basis for the NX2 plasma focus (PF) device using two beryllium fast-neutron activation detectors at 0° and 90° to the PF axis. Measurements were performed for deuterium gas pressures in the range 6–16 mbar, and positive correlations between neutron yield and anisotropy were observed at all pressures. Subsequently, at one deuterium gas pressure (13 mbar), the contribution to the fusion yield produced by the forwardly-directed D{sup +} ion beam, emitted from the plasma pinch, was investigated by using a circular Pyrex plate to obstruct the beam and suppress its fusion contribution. Neutron measurements were performed with the obstacle positioned at two distances from the anode tip, and also without the obstacle. It was found that ~ 80% of the neutron yield originates in the plasma pinch column and just above that. In addition, proton pinhole imaging was performed from the 0° and 90° directions to the pinch. The obtained proton images are consistent with the conclusion that DD fusion is concentrated (~ 80%) in the pinch column region.

  9. Absorption of high-frequency electromagnetic energy in a high-temperature plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeyev, R S; Shafranov, V D

    1958-07-01

    In this paper an analysis of the cyclotron and Cherenkov mechanisms is given. These are two fundamental mechanisms for noncollisional absorption of electromagnetic radiation by plasma in a magnetic field. The expressions for the dielectric permeability tensor, for plasma with a nonisotropic temperature distribution in a magnetic field, are obtained by integrating the kinetic equation with Lagrangian particle co-ordinates in a form suitable to allow a comprehensive physical interpretation of the absorption mechanisms. The oscillations of a plasma column stabilized by a longitudinal field have been analyzed. For uniform plasma, the frequency spectrum has been obtained together with the direction of electromagnetic wave propagation when both the cyclotron and Cherenkov absorption mechanisms take place. The influence of nonlinear effects on the electromagnetic wave absorption and the part which cyclotron and Cherenkov absorption play in plasma heating have also been investigated.

  10. Dynamic stability of self-similar solutions for a plasma pinch

    International Nuclear Information System (INIS)

    Ma, Sifeng.

    1988-01-01

    Linear Magnetohydrodynamic (MHD) stability theory is applied to a class of self-similar solutions which describe implosion, expansion and oscillation of an infinitely conducting plasma column. The equations of perturbation are derived in the Lagrangian coordinate system. Numerical procedures via the finite-element method are formulated, and general aspects of dynamic stability are discussed, The dynamic stability of the column when it is oscillatory is studied in detail using the Floquet theory, and the characteristic exponent is calculated numerically. A-pinch configuration is examined. It is found that self-similar oscillations in general destabilize the continua in the MHD spectrum, and parametric instability results

  11. Response of steel box columns in fire conditions

    Directory of Open Access Journals (Sweden)

    Mahmood Yahyai

    2017-05-01

    Full Text Available Effect of elevated temperatures on the mechanical properties of steel, brings the importance of investigating the effect of fire on the steel structures anxiously. Columns, as the main load-carrying part of a structure, can be highly vulnerable to the fire. In this study, the behavior of steel gravity columns with box cross section exposed to fire has been investigated. These kinds of columns are widely used in common steel structures design in Iran. In current study, the behavior of such columns in fire conditions is investigated through the finite element method. To perform this, the finite element model of a steel column which has been previously tested under fire condition, was prepared. Experimental loading and boundary conditions were considered in the model and was analyzed. Results were validated by experimental data and various specimens of gravity box columns were designed according to the Iran’s steel buildings code, and modeled and analyzed using Abaqus software. The effect of width to thickness ratio of column plates, the load ratio and slenderness on the ultimate strength of the column was investigated, and the endurance time was estimated under ISO 834 standard fire curve. The results revealed that an increase in width to thickness ratio and load ratio leads to reduction of endurance time and the effect of width to thickness ratio on the ultimate strength of the column decreases with temperature increase.

  12. Ductility of reinforced concrete columns confined with stapled strips

    International Nuclear Information System (INIS)

    Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.

    2015-01-01

    Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)

  13. Retrofit of distillation columns in biodiesel production plants

    International Nuclear Information System (INIS)

    Nguyen, Nghi; Demirel, Yasar

    2010-01-01

    Column grand composite curves and the exergy loss profiles produced by the Column-Targeting Tool of the Aspen Plus simulator are used to assess the performance of the existing distillation columns, and reduce the costs of operation by appropriate retrofits in a biodiesel production plant. Effectiveness of the retrofits is assessed by means of thermodynamics and economic improvements. We have considered a biodiesel plant utilizing three distillation columns to purify biodiesel (fatty acid methyl ester) and byproduct glycerol as well as reduce the waste. The assessments of the base case simulation have indicated the need for modifications for the distillation columns. For column T202, the retrofits consisting of a feed preheating and reflux ratio modification have reduced the total exergy loss by 47%, while T301 and T302 columns exergy losses decreased by 61% and 52%, respectively. After the retrofits, the overall exergy loss for the three columns has decreased from 7491.86 kW to 3627.97 kW. The retrofits required a fixed capital cost of approximately $239,900 and saved approximately $1,900,000/year worth of electricity. The retrofits have reduced the consumption of energy considerably, and leaded to a more environmentally friendly operation for the biodiesel plant considered.

  14. Interpretation of the lime column penetration test

    International Nuclear Information System (INIS)

    Liyanapathirana, D S; Kelly, R B

    2010-01-01

    Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.

  15. Behaviour of FRP confined concrete in square columns

    OpenAIRE

    Diego Villalón, Ana de; Arteaga Iriarte, Ángel; Fernandez Gomez, Jaime Antonio; Perera Velamazán, Ricardo; Cisneros, Daniel

    2015-01-01

    A significant amount of research has been conducted on FRP-confined circular columns, but much less is known about rectangular/square columns in which the effectiveness of confinement is much reduced. This paper presents the results of experimental investigations on low strength square concrete columns confined with FRP. Axial compression tests were performed on ten intermediate size columns. The tests results indicate that FRP composites can significantly improve the bearing capacity and duc...

  16. Numerical Simulations of Settlement of Jet Grouting Columns

    Directory of Open Access Journals (Sweden)

    Juzwa Anna

    2016-03-01

    Full Text Available The paper presents the comparison of results of numerical analyses of interaction between group of jet grouting columns and subsoil. The analyses were conducted for single column and groups of three, seven and nine columns. The simulations are based on experimental research in real scale which were carried out by authors. The final goal for the research is an estimation of an influence of interaction between columns working in a group.

  17. Strengthening of Steel Columns under Load: Torsional-Flexural Buckling

    Directory of Open Access Journals (Sweden)

    Martin Vild

    2016-01-01

    Full Text Available The paper presents experimental and numerical research into the strengthening of steel columns under load using welded plates. So far, the experimental research in this field has been limited mostly to flexural buckling of columns and the preload had low effect on the column load resistance. This paper focuses on the local buckling and torsional-flexural buckling of columns. Three sets of three columns each were tested. Two sets corresponding to the base section (D and strengthened section (E were tested without preloading and were used for comparison. Columns from set (F were first preloaded to the load corresponding to the half of the load resistance of the base section (D. Then the columns were strengthened and after they cooled, they were loaded to failure. The columns strengthened under load (F had similar average resistance as the columns welded without preloading (E, meaning the preload affects even members susceptible to local buckling and torsional-flexural buckling only slightly. This is the same behaviour as of the tested columns from previous research into flexural buckling. The study includes results gained from finite element models of the problem created in ANSYS software. The results obtained from the experiments and numerical simulations were compared.

  18. Study on two phase flow characteristics in annular pulsed extraction column with different ratio of annular width to column diameter

    International Nuclear Information System (INIS)

    Qin Wei; Dai Youyuan; Wang Jiading

    1994-01-01

    Annular pulsed extraction column can successfully provide large throughput and can be made critically safe for fuel reprocessing. This investigation is to study the two phase flow characteristics in annular pulsed extraction column with four different annular width. 30% TBP (in kerosene)-water is used (water as continuous phase). Results show that modified Pratt correlation is valid under the experimental operation conditions for the annular pulsed extraction column. The characteristic velocity U K decreased with the increase of energy input and increased with the increase of the ratio of annular width to column diameter. Flooding velocity correlation is suggested. The deviation of the calculated values from the experimental data is within +20% for four annular width in a pulsed extraction column

  19. Collapse of tall granular columns in fluid

    Science.gov (United States)

    Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves

    2017-06-01

    Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.

  20. Winter School on Physics with Trapped Charged Particles - Abstracts and slides

    International Nuclear Information System (INIS)

    Pedersen, T.S.; Thompson, R.C.; Madsen, N.; Champenois, C.; Anderegg, F.; Fajans, J.; Knoop, M.; Scott Hangst, J.; Hilico, L.; Ulmer, S.; Blaum, K.; Drewsen, M.; Roos, C.; Schmidt, P.

    2016-01-01

    This winter school covered various topics of the physics of trapped charged particles. Lectures covered basic trap physics and recent developments in Penning traps, Paul traps..., collective behavior and non-neutral plasmas, as well as applications for fundamental physics, laser cooling, precision spectroscopy and quantum information. This document gathers a booklet of abstracts and the available slides of the presentations

  1. Potential distribution of a nonuniformly charged ellipsoid

    International Nuclear Information System (INIS)

    Kiwamoto, Y.; Aoki, J.; Soga, Y.

    2004-01-01

    A convenient formula is obtained for fast calculation of the three-dimensional potential distribution associated with a spatially varying charge-density distribution by reconstructing it as a superposed set of nested spheroidal shells. It is useful for experimental analyses of near-equilibrium states of non-neutral plasmas and for quick evaluation of the gravity field associated with stellar mass distributions

  2. CUB DI (Deionization) column control system

    International Nuclear Information System (INIS)

    Seino, K.C.

    1999-01-01

    For the old MR (Main Ring), deionization was done with two columns in CUB, using an ion exchange process. Typically 65 GPM of LCW flew through a column, and the resistivity was raised from 3 Mohm-cm to over 12 Mohm-cm. After a few weeks, columns lost their effectiveness and had to be regenerated in a process involving backwashing and adding hydrochloric acid and sodium hydroxide. For normal MR operations, LCW returned from the ring and passed through the two columns in parallel for deionization, although the system could have been operated satisfactorily with only one in use. A 3000 gallon reservoir (the Spheres) provided a reserve of LCW for allowing water leaks and expansions in the MR. During the MI (Main Injector) construction period, the third DI column was added to satisfy requirements for the MI. When the third column was added, the old regeneration controller was replaced with a new controller based on an Allen-Bradley PLC (i.e., SLC-5/04). The PLC is widely used and well documented, and therefore it may allow us to modify the regeneration programs in the future. In addition to the above regeneration controller, the old control panels (which were used to manipulate pumps and valves to supply LCW in Normal mode and to do Int. Recir. (Internal Recirculation) and Makeup) were replaced with a new control system based on Sixtrak Gateway and I/O modules. For simplicity, the new regeneration controller is called as the US Filter system, and the new control system is called as the Fermilab system in this writing

  3. Chiral separation of (d- and (l-enantiomers of doxylamine succinate in rat plasma

    Directory of Open Access Journals (Sweden)

    Tadiboyina Sirisha

    2015-12-01

    Full Text Available A selective chiral ultra fast liquid chromatography (UFLC-DAD method was developed and validated to separate and quantify the (d- and (l-enantiomers of doxylamine in rat plasma. After extraction of the plasma samples with acetonitrile, the separation of doxylamine succinate enantiomers and internal standard (I.S., diphenhydramine hydrochloride was achieved on a cellulose Tris (4-chloro,3-methylphenylcarbamate column with a mobile phase of 20 mM ammonium bicarbonate buffer–acetonitrile (65:35 v/v with 0.15% diethylamine in the buffer at a flow rate of 1.0 mL/min. The diode array (DAD detection wavelength was set at 220 nm. The peaks obtained were identified as (d and (l by injecting the pure (d form into the liquid chromatography and comparing the chromatograms. The effect of column oven temperature on the retention of doxylamine and mobile phase variables which have an effect on the enantiomers separation like ionic strength, type and concentration of organic modifier was studied. Linear calibration curves were obtained over the range of 100–1400 ng/mL in plasma for both enantiomers (R2 > 0.995. The mean extraction recoveries were 94.5–104.7% of rat plasma. The mean relative standard deviation (RSD% of accuracy and intra-day and inter-day precision for both enantiomers were ⩽10%. The method can be further applied to determine the pharmacokinetics of (d- and (l-enantiomers in rat plasma.

  4. 2 D gel based analysis of biological variability of the human plasma proteome

    DEFF Research Database (Denmark)

    Rentsch, Maria Louise; Jessen, Flemming

    individuals and within an individual changes will also happen over time (e.g. after meal intake). Thus, the aim of the present study was to examine the inter-individual variability of plasma protein levels in humans after meal intake. Five subjects consumed three single meals in a randomised order separated...... by one-week interval. Blood samples were drawn before the meal intake and five times during 24 hours for proteome analysis. Plasma was fractionated by use of IgY-12 spin column depleting the 12 highly abundant proteins and further processed for two-dimensional gel electrophoresis. The plasma proteome...

  5. Study of opening switch characteristics of a plasma focus

    International Nuclear Information System (INIS)

    Rhee, M.J.; Schneider, R.F.

    1985-01-01

    It is shown that a current charged transmission line and an opening switch can be used as an inductive energy storage system to produce a high power pulse. A plasma focus device, in which a transmission line is inserted in series with the capacitor bank and a coaxial gun, is considered as an inductive energy storage system. The m = 0 instability in the plasma focus is utilized as an opening switch and the disrupted plasma column is considered as bipolar diode. The system is described preferably by the transmission line theory rather than the lumped circuit theory. The relationship between the output voltage and the current drop is given by V = ΔIZ, where Z is the characteristic impedance of the transmission line. The current drop ΔI depends on the mismatched load impedance of the plasma diode which is governed by nature of the m = 0 instability

  6. NOx retention in scrubbing column

    International Nuclear Information System (INIS)

    Nakazone, A.K.; Costa, R.E.; Lobao, A.S.T.; Matsuda, H.T.; Araujo, B.F.

    1988-07-01

    During the UO 2 dissolution in nitric acid, some different species of NO x are released. The off gas can either be refluxed to the dissolver or be released and retained on special columns. The final composition of the solution is the main parameter to take in account. A process for nitrous gases retention using scubber columns containing H 2 O or diluted HNO 3 is presented. Chemiluminescence measurement was employed to NO x evalution before and after scrubbing. Gas flow, temperature, residence time are the main parameters considered in this paper. For the dissolution of 100g UO 2 in 8M nitric acid, a 6NL/h O 2 flow was the best condition for the NO/NO 2 oxidation with maximum adsorption in the scrubber columns. (author) [pt

  7. Separation of substances in rotating coiled columns: from trace elements to microparticles

    International Nuclear Information System (INIS)

    Spivakov, B.Ya.; Maryutina, T.A.; Fedotov, P.S.; Ignatova, S.N.; Katasonova, O.N.; Damen, I.; Vennrikh, R.

    2002-01-01

    The wide possibilities of using the rotating spiral columns by analysis of the material, differing in their chemical and phase composition, in particular by determining the rare earth elements impurities (REE) in the highly pure calcium chloride are described. The analysis is based on the REE group extraction through the liquid chromatography method with the free immovable phase and application of the octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphineoxide in the chloroform with their subsequent determination through the method of the mass spectroscopy with the inductively bound plasma. The limits of the REE determination for this methodology are at the ng/g level; the values of the relative standard deviation do not exceed 15 - 20 % [ru

  8. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Driscoll, C. F.; Dubin, D. H. E.; O'Neil, T. M.

    2009-11-01

    Electron Acoustic Waves (EAW) are the low frequency branch of electrostatic plasma waves. These waves exist in neutralized plasmas, pure electron plasmas and in pure ion plasmasfootnotetextF. Anderegg et al., PRL 102, 095001 (2009) and PoP 16, 055705 (2009). (where the name is deceptive). Here, we observe standing mθ= 0 mz= 1 EAWs in a pure ion plasma column. At small amplitude, the EAWs have a phase velocity vph ˜1.4 v, and the frequencies are in close agreement with theory. At moderate amplitudes, waves can be excited over a broad range of frequencies, with observed phase velocities in the range of 1.4 v vph diagnostic shows that particles slower than vph oscillate in phase with the wave, while particles moving faster than vph oscillate 180^o out of phase with the wave. From a fluid perspective, this gives an unusual negative dynamical compressibility. That is, the wave pressure oscillations are 180^o out of phase from the density oscillations, almost fully canceling the electrostatic restoring force, giving the low and malleable frequency.

  9. Modalization in the Political Column of Tempo Magazine

    OpenAIRE

    Rahmah, Maria Betti Sinaga and

    2017-01-01

    The study focuses on analyzing the use of modalization in the Political Column of Tempo Magazine. The objectives were to find out the type of modalization and to describe the use of modalization in the Political Column of Tempo magazine. The data were taken from Political Column of Tempo magazine published in June and July 2017. The source of data was Political Column in Tempo magazine. The data analysis applied descriptive qualitative research. There were 135 clauses which contained Modaliza...

  10. Column, particularly extraction column, for fission and/or breeder materials

    International Nuclear Information System (INIS)

    Vietzke, H.; Pirk, H.

    1980-01-01

    An absorber rod with a B 4 C insert is situated in the long extraction column for a uranyl nitrate solution or a plutonium nitrate solution. The geometrical dimensions are designed for a high throughput with little corrosion. (DG) [de

  11. Posterior column reconstruction improves fusion rates at the level of osteotomy in three-column posterior-based osteotomies.

    Science.gov (United States)

    Lewis, Stephen J; Mohanty, Chandan; Gazendam, Aaron M; Kato, So; Keshen, Sam G; Lewis, Noah D; Magana, Sofia P; Perlmutter, David; Cape, Jennifer

    2018-03-01

    To determine the incidence of pseudarthrosis at the osteotomy site after three-column spinal osteotomies (3-COs) with posterior column reconstruction. 82 consecutive adult 3-COs (66 patients) with a minimum of 2-year follow-up were retrospectively reviewed. All cases underwent posterior 3-COs with two-rod constructs. The inferior facets of the proximal level were reduced to the superior facets of the distal level. If that was not possible, a structural piece of bone graft either from the local resection or a local rib was slotted in the posterior column defect to re-establish continual structural posterior bone across the lateral margins of the resection. No interbody cages were used at the level of the osteotomy. There were 34 thoracic osteotomies, 47 lumbar osteotomies and one sacral osteotomy with a mean follow-up of 52 (24-126) months. All cases underwent posterior column reconstructions described above and the addition of interbody support or additional posterior rods was not performed for fusion at the osteotomy level. Among them, 29 patients underwent one or more revision surgeries. There were three definite cases of pseudarthrosis at the osteotomy site (4%). Six revisions were also performed for pseudarthrosis at other levels. Restoration of the structural integrity of the posterior column in three-column posterior-based osteotomies was associated with > 95% fusion rate at the level of the osteotomy. Pseudarthrosis at other levels was the second most common reason for revision following adjacent segment disease in the long-term follow-up.

  12. Decontamination possibilities of high-toxic wastes by means of dense plasma generators

    International Nuclear Information System (INIS)

    Rutberg, P.G.; Kolikov, V.A.; Bogomaz, A.A.; Budin, A.V.

    1997-01-01

    In present time the idea of plasma generators application for the high-toxic agents and wastes decontamination has become very urgent. It is known that chemical bonds energy of some molecules being part of these substances is so high that it is impossible to destroy them using traditional methods. Taking into account the fact that the temperature of plasma generator's arc column may be of tens eV, and its energy of hundreds kJ, one may state that any known chemical substances taken in quite large amount, may be dissociated to the atoms. In this paper simplified construction of plasma generator and technological scheme of plasmachemical installation are presented. (author)

  13. Effect of pre- and post-column band broadening on the performance of high-speed chromatography columns under isocratic and gradient conditions.

    Science.gov (United States)

    Vanderlinden, Kim; Broeckhoven, Ken; Vanderheyden, Yoachim; Desmet, Gert

    2016-04-15

    We report on the results of an experimental and theoretical study of the effect of the extra-column band broadening (ECBB) on the performance of narrow-bore columns filled with the smallest particles that are currently commercially available. Emphasis is on the difference between the effect of ECBB under gradient and isocratic conditions, as well as on the ability to model and predict the ECBB effects using well-established band broadening expressions available from the theory of chromatography. The fine details and assumptions that need to be taken into account when using these expressions are discussed. The experiments showed that, the steeper the gradient, the more pronounced the extra-column band broadening losses become. Whereas the pre-column band broadening can in both isocratic and gradient elution be avoided by playing on the possibilities to focus the analytes on top of the column (e.g. by using the POISe injection method when running isocratic separations), the post-column extra-column band broadening is inescapable in both cases. Inducing extra-column band broadening by changing the inner diameter of the post-column tubing from 65 to 250 μm, we found that all peaks in the chromatogram are strongly affected (around a factor of 1.9 increase in relative peak width) when running steep gradients, while usually only the first eluting peak was affected in the isocratic mode or when running shallow gradients (factor 1.6-1.8 increase in relative peak width for the first eluting analyte). Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Study of Pulsed vs. RF Plasma Properties for Surface Processing Applications

    Science.gov (United States)

    Tang, Ricky; Hopkins, Matthew; Barnat, Edward; Miller, Paul

    2015-09-01

    The ability to manipulate the plasma parameters (density, E/N) was previously demonstrated using a double-pulsed column discharge. Experiments extending this to large-surface plasmas of interest to the plasma processing community were conducted. Differences between an audio-frequency pulsed plasma and a radio-frequency (rf) discharge, both prevalent in plasma processing applications, were studied. Optical emission spectroscopy shows higher-intensity emission in the UV/visible range for the pulsed plasma comparing to the rf plasma at comparable powers. Data suggest that the electron energy is higher for the pulsed plasma leading to higher ionization, resulting in increased ion density and ion flux. Diode laser absorption measurements of the concentration of the 1S5 metastable and 1S4 resonance states of argon (correlated with the plasma E/N) provide comparisons between the excitation/ionization states of the two plasmas. Preliminary modeling efforts suggest that the low-frequency polarity switch causes a much more abrupt potential variation to support interesting transport phenomena, generating a ``wave'' of higher temperature electrons leading to more ionization, as well as ``sheath capture'' of a higher density bolus of ions that are then accelerated during polarity switch.

  15. Computational study of sheath structure in oxygen containing plasmas at medium pressures

    Science.gov (United States)

    Hrach, Rudolf; Novak, Stanislav; Ibehej, Tomas; Hrachova, Vera

    2016-09-01

    Plasma mixtures containing active species are used in many plasma-assisted material treatment technologies. The analysis of such systems is rather difficult, as both physical and chemical processes affect plasma properties. A combination of experimental and computational approaches is the best suited, especially at higher pressures and/or in chemically active plasmas. The first part of our study of argon-oxygen mixtures was based on experimental results obtained in the positive column of DC glow discharge. The plasma was analysed by the macroscopic kinetic approach which is based on the set of chemical reactions in the discharge. The result of this model is a time evolution of the number densities of each species. In the second part of contribution the detailed analysis of processes taking place during the interaction of oxygen containing plasma with immersed substrates was performed, the results of the first model being the input parameters. The used method was the particle simulation technique applied to multicomponent plasma. The sheath structure and fluxes of charged particles to substrates were analysed in the dependence on plasma pressure, plasma composition and surface geometry.

  16. Simultaneous determination of caffeine, theophylline and theobromine in human plasma by on-line solid-phase extraction coupled to reversed-phase chromatography.

    Science.gov (United States)

    Emara, Samy

    2004-10-01

    A reversed-phase liquid chromatographic column switching system was described for the determination of caffeine (CF), theophylline (TH) and theobromine (TB) in human plasma with a direct injection procedure. A short protein-coated mu Bondapak CN silica pre-column (20 x 3 mm, i.d.) was used for enrichment of the drugs and clean up from weakly retained plasma components using phosphate buffer saline pH 7.4. After washing step, the retained drugs were flushed into a reversed-phase column (5 microm TSK gel ODS-80 TM, 150 x 4.6 mm i.d.) with a mobile phase of methanol-0.01 M phosphate buffer, pH 3.5 (30:70, v/v) for the final separation. The eluent was monitored with a UV detector at 275 nm. The resulting chromatograms showed no interference from endogenous plasma components. A linear relationship between the concentration of drug and peak height was confirmed in the range of 0.5-20 microg/mL for all drugs. High extraction recoveries from plasma ranging from 96.12 to 100.32% were achieved. Validation of the method was examined performing intra- and inter-day accuracy and precision and was found to be satisfactory. The coefficients of variation of the three drugs were less than 3% for intra-day and less than 4% for inter-day run assays.

  17. Oscillations of the positive column plasma due to ionization wave propagation and two-dimensional structure of striations

    International Nuclear Information System (INIS)

    Golubovskii, Yu B; Kozakov, R V; Wilke, C; Behnke, J; Nekutchaev, V O

    2004-01-01

    Time and space resolved measurements of the plasma potential in axial and radial directions in S- and P-striations in neon are performed. The measurements in different radial positions were carried out with high spatial resolution by means of simultaneous displacement of electrodes relative to the stationary probe. The plasma potential was found to be a superposition of the potentials of ionization wave and plasma oscillations relative to the electrodes. A method of decomposition of the measured spatio-temporal structure of the potential in components associated with the plasma oscillations and ionization wave propagation is proposed. A biorthogonal decomposition of the spatio-temporal structure of the potential is performed. A comparison of the decomposition results obtained by the two methods is made. The experiments revealed a two-dimensional structure of the potential field in an ionization wave. Qualitative discussions of the reasons for the occurrence of this two-dimensional structure are presented based on the analysis of the kinetic equation and the equation for the potential

  18. Water hammer with column separation : a historical review

    NARCIS (Netherlands)

    Bergant, A.; Simpson, A.R.; Tijsseling, A.S.

    2006-01-01

    Column separation refers to the breaking of liquid columns in fully filled pipelines. This may occur in a water-hammer event when the pressure in a pipeline drops to the vapor pressure at specific locations such as closed ends, high points or knees (changes in pipe slope). The liquid columns are

  19. Cobalamin speciation using reversed-phase micro-high-performance liquid chromatography interfaced to inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Yanes, Enrique G.; Miller-Ihli, Nancy J.

    2004-01-01

    Micro-high-performance liquid chromatography interfaced to inductively coupled plasma mass spectrometry was optimized for the determination and separation of a mixture of cobalt containing species. Four cobalamin species (cyanocobalamin, hydroxocobalamin, methylcobalamin, and 5'-deoxyadenosylcobalamin) representing the various forms of vitamin B12 as well as the harmful corrinoid analogue cobinamide dicyanide were separated using reversed-phase microcapillary chromatography with columns containing C18 packing material with a 2-μm particle size. Selection of organic solvents for the separation took into consideration compatibility with the inductively coupled plasma mass spectrometer being used for element specific detection. Optimized method conditions included use of a methanol gradient and make-up solution for the nebulizer. Some issues associated with dead volume were overcome by the extension of the gradient program. The total analysis time was 52 min. The column-to-column variability was evaluated and was found to be very reasonable (9% RSD on average), confirming that this method is rugged and that the technology should be easily transferred to other laboratories

  20. Radiative transfer in a strongly magnetized plasma. I. Effects of Anisotropy

    International Nuclear Information System (INIS)

    Nagel, W.

    1981-01-01

    We present results of radiative transfer calculations for radiating slabs and columns of strongly magnetized plasma. The angular dependence of the escaping radiation was found numerically by Feautrier's method, using the differential scattering cross sections derived by Ventura. We also give an approximate analytical expression for the anisotropy of the outgoing radiation, based on a system of two coupled diffusion equations for ordinary and extraordinary photons. Giving the polarization dependence of the beaming pattern of radiating slabs as well as columns, we generalize previous results of Basko and Kanno. Some implications for models of the pulsating X-ray source Her X-1 are discussed