WorldWideScience

Sample records for plasma flow measurement

  1. 2. Basis of measurement of plasma flow. 2.3 Plasma flow measurements. Spectroscopic methods

    International Nuclear Information System (INIS)

    Kado, Shinichiro

    2007-01-01

    The construction of optical system, optical fiber incident system, reciprocal linear dispersion, grating smile and astigmatism of the reflection plane diffraction grating spectrometer are explained in order to measure the plasma flow. The specification of flow measurement and evaluation of 0 point of velocity are stated. For examples of measurements, the fine structures of He II (Δn = 3 - 4) in material and plasma(MAP)-II of Tokyo University, plasma flow measurement by the charge exchange recombination spectroscopy using Large Helical Device and by Zeeman spectroscopy using TRIAM-1M tokamak plasma are stated. (S.Y.)

  2. Thomson scattering measurements from asymmetric interpenetrating plasma flows

    Energy Technology Data Exchange (ETDEWEB)

    Ross, J. S., E-mail: ross36@llnl.gov; Moody, J. D.; Fiuza, F.; Ryutov, D.; Divol, L.; Huntington, C. M.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

    2014-11-15

    Imaging Thomson scattering measurements of collective ion-acoustic fluctuations have been utilized to determine ion temperature and density from laser produced counter-streaming asymmetric flows. Two foils are heated with 8 laser beams each, 500 J per beam, at the Omega Laser facility. Measurements are made 4 mm from the foil surface using a 60 J 2ω probe laser with a 200 ps pulse length. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the multi-ion species, asymmetric flows theoretical form factor for the ion feature such that the ion temperatures, ion densities, and flow velocities for each plasma flow are determined.

  3. Flowing dusty plasma experiments: generation of flow and measurement techniques

    Science.gov (United States)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2016-12-01

    A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a \\Pi -shaped dusty plasma experimental device with micron size kaolin/melamine formaldehyde particles embedded in a background of argon plasma created by a direct current glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super particle identification code, particle image velocimetry analysis and the excitation of dust acoustic waves. The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral drag force responsible for the generation as well as the attenuation of the dust fluid flow is made. These techniques can be usefully employed in laboratory devices to investigate linear and non-linear collective excitations in a flowing dusty plasma.

  4. Viscosity estimation utilizing flow velocity field measurements in a rotating magnetized plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2008-01-01

    The importance of viscosity in determining plasma flow structures has been widely recognized. In laboratory plasmas, however, viscosity measurements have been seldom performed so far. In this paper we present and discuss an estimation method of effective plasma kinematic viscosity utilizing flow velocity field measurements. Imposing steady and axisymmetric conditions, we derive the expression for radial flow velocity from the azimuthal component of the ion fluid equation. The expression contains kinematic viscosity, vorticity of azimuthal rotation and its derivative, collision frequency, azimuthal flow velocity and ion cyclotron frequency. Therefore all quantities except the viscosity are given provided that the flow field can be measured. We applied this method to a rotating magnetized argon plasma produced by the Hyper-I device. The flow velocity field measurements were carried out using a directional Langmuir probe installed in a tilting motor drive unit. The inward ion flow in radial direction, which is not driven in collisionless inviscid plasmas, was clearly observed. As a result, we found the anomalous viscosity, the value of which is two orders of magnitude larger than the classical one. (author)

  5. Thomson scattering measurements of ion interpenetration in cylindrically converging, supersonic magnetized plasma flows

    Science.gov (United States)

    Swadling, George

    2015-11-01

    Ion interpenetration driven by high velocity plasma collisions is an important phenomenon in high energy density environments such as the interiors of ICF vacuum hohlraums and fast z-pinches. The presence of magnetic fields frozen into these colliding flows further complicates the interaction dynamics. This talk focuses on an experimental investigation of ion interpenetration in collisions between cylindrically convergent, supersonic, magnetized flows (M ~10, Vflow ~ 100km/s, ni ~ 1017cm-3) . The flows used in this study were plasma ablation streams produced by tungsten wire array z-pinches, driven by the 1.4MA, 240ns Magpie facility at Imperial College, and diagnosed using a combination of optical Thomson scattering, Faraday rotation and interferometry. Optical Thomson scattering (TS) provides time-resolved measurements of local flow velocity and plasma temperature across multiple (7 to 14) spatial positions. TS spectra are recorded simultaneously from multiple directions with respect to the probing beam, resulting in separate measurements of the rates of transverse diffusion and slowing-down of the ion velocity distribution. The measurements demonstrate flow interpenetration through the array axis at early time, and also show an axial deflection of the ions towards the anode. This deflection is induced by a toroidal magnetic field (~ 10T), frozen into the plasma that accumulates near the axis. Measurements obtained later in time show a change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams, and rapid radial collapse of the magnetized plasma column. The quantitative nature of the spatial profiles of the density, flow velocities and ion temperatures measured in these experiments will allow detailed verification of MHD and PIC codes used by the HEDP community. Work Supported by EPSRC (Grant No. EP/G001324/1), DOE (Cooperative Agreement Nos. DE-F03-02NA00057 & DE-SC-0001063) & Sandia National

  6. Directional rf probe for measurement of conductivity of flowing plasmas

    International Nuclear Information System (INIS)

    Jayakumar, R.; Chakravarthy, D.P.; Rohatgi, V.K.

    1977-01-01

    An electrodeless immersible rf probe for measurement of plasma conductivity in the range 0.01 to 100 mho/m has been designed and fabricated. The probe, with an overall diameter of 11 mm, employs unidirectional electromagnetic field lines which reduce the inaccuracies caused by insertion of the probe in a flowing plasma. In the range studied the probe output shows a linear relationship with the conductivity of the medium. Such probes are of interest in the study of MHD and reentry plasmas

  7. Optical measurements of lateral energy flow and plasma motion in laser-produced plasmas

    International Nuclear Information System (INIS)

    Benjamin, R.F.; Riffle, J.H.

    1979-01-01

    An optical system consisting of a telephoto lens and multi-image camera is described and the experimental results and their implications are presented. We will also describe the opto-electronic system that will measure the time history of the energy flow with sub-nanosecond resolution. The system will be useful to study both one- and two-dimensional geometries. The third optical diagnostic is a laser probe utilizing detection by the opto-electronic system mentioned above. This diagnostic measures plasma motion as well as energy flow. The laser probe and detection system mounts directly onto the target chamber at LASLs Gemini CO 2 laser, causing severe alignment and stability problems whose solutions will be shown

  8. 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.

  9. Measurements of ion temperature and flow of pulsed plasmas produced by a magnetized coaxial plasma gun device using an ion Doppler spectrometer

    Science.gov (United States)

    Kitagawa, Y.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    It is important to know surface damage characteristics of plasma-facing component materials during transient heat and particle loads such as type I ELMs. A magnetized coaxial plasma gun (MCPG) device has been used as transient heat and particle source in ELM simulation experiments. Characteristics of pulsed plasmas produced by the MCPG device play an important role for the plasma material interaction. In this study, ion temperature and flow velocity of pulsed He plasmas were measured by an ion Doppler spectrometer (IDS). The IDS system consists of a light collection system including optical fibers, 1m-spectrometer and a 16 channel photomultiplier tube (PMT) detector. The IDS system measures the width and Doppler shift of HeII (468.58 nm) emission line with the time resolution of 1 μs. The Doppler broadened and shifted spectra were measured with 45 and 135 degree angles with respect to the plasmoid traveling direction. The observed emission line profile was represented by sum of two Gaussian components to determine the temperature and flow velocity. The minor component at around the wavelength of zero-velocity was produced by the stationary plasma. As the results, the ion velocity and temperature were 68 km/s and 19 eV, respectively. Thus, the He ion flow energy is 97 eV. The observed flow velocity agrees with that measured by a time of flight technique.

  10. Measurement of ion temperature and flow in RF start-up plasmas in TST-2 and LATE

    International Nuclear Information System (INIS)

    Tsuda, Shintaro; Ejiri, Akira; Takase, Yuichi; Tsujii, Naoto; Takeuchi, Toshihiro; Tanaka, Hitoshi; Uchida, Masaki; Maekawa, Takashi

    2015-01-01

    The ion temperature and flow of RF start-up plasmas in TST-2 and LATE were measured using a visible spectrometer. The plasma currents were 9 kA and 8 kA, respectively. The typical ion temperatures T i and toroidal flow V ϕ were 4 eV and 1 km/s, respectively, in the TST-2 plasma sustained by the lower hybrid wave (20 kW) and T i ∼ 10 eV and V ϕ ∼ 5 km/s in the LATE plasma sustained by the electron cyclotron wave (50 kW). The poloidal flow velocities were comparable to the toroidal velocities. The ion temperatures were relatively high and the ion orbit loss can be significant. (author)

  11. Plasma flow measurement using directional Langmuir probe under weakly ion-magnetized conditions

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Kenichi; Okamoto, Atsushi [Graduate School of Science, Nagoya Univ., Nagoya (Japan); Yoshimura, Shinji; Tanaka, Masayoshi Y. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-07-01

    It is both experimentally and theoretically demonstrated that ion flow velocity at an arbitrary angle with respect to the magnetic field can be measured with a directional Langmuir probe. Based on the symmetry argument, we show that the effect of magnetic field on directional probe current is exactly canceled in determining the ion flow velocity, and obtain the generalized relation between flow velocity and directional probe currents valid for any flowing direction. The absolute value of the flow velocity is determined by an in situ calibration method of the probe. The applicability limit of the present method to a strongly ion-magnetized plasma is experimentally examined. (author)

  12. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  13. Probing of flowing electron plasmas

    International Nuclear Information System (INIS)

    Himura, H.; Nakashima, C.; Saito, H.; Yoshida, Z.

    2001-01-01

    Probing of streaming electron plasmas with finite temperature is studied. For the first time, a current-voltage characteristic of an electric probe is measured in electron plasmas. Due to the fast flow of the electron plasmas, the characteristic curve spreads out significantly and exhibits a long tail. This feature can be explained calculating the currents collected to the probe. In flowing electron plasmas, the distribution function observed in the laboratory frame is non-Maxwellian even if the plasmas come to a state of thermal equilibrium. Another significant feature of the characteristic is that it determines a floating potential where the current equals zero, despite there being very few ions in the electron plasma. A high impedance probe, which is popularly used to determine the space potential of electron plasmas, outputs the potential. The method is available only for plasmas with density much smaller than the Brillouin limit

  14. Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

    International Nuclear Information System (INIS)

    Jacoby, B.A.; York, T.M.

    1979-02-01

    With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

  15. Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

    2010-01-01

    Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

  16. Research status of fast flows and shocks in laboratory plasmas. Supersonic plasma flow and shock waves in various magnetic channels

    International Nuclear Information System (INIS)

    Inutake, Masaaki; Ando, Akira

    2007-01-01

    Fast plasma flow is produced by Magneto-Plasma-Dynamic Arcjet (MPDA). The properties of fast flow and shock wave in various magnetic channels are reported by the experiment results. Fast plasma flow by MPDA, shocked flow in the magnetic channel, supersonic plasma flow in the divergence magnetic nozzle, ion acoustic wave in the mirror field, transonic flow and sonic throat in the magnetic Laval nozzle, fast flow in the helical magnetic channel, and future subjects are reported. Formation of the supersonic plasma flow by the divergence magnetic nozzle and effects of background gas, helical-kink instability in the fast plasma jet, and formation of convergence magnetic nozzle near outlet are described. From the phase difference of azimuthal and axial probe array signals, the plasma has twisted structure and it rotates in the same direction of the twist. Section of MPDA, principle of magnetic acceleration of MPDA, HITOP, relation among velocities, temperature, and Mach number of He ion and atom and the discharge current, distribution of magnetic-flux density in the direction of electromagnetic field, measurement of magnetic field near MPDA exit are illustrated. (S.Y.)

  17. Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

    2014-01-01

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n plu , which is estimated from the current and the drift velocity, and the gas flow velocity v gas is examined. It is found that the dependence of the density on the gas flow velocity has relations of n plu ∝ log(v gas ). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity

  18. Flow morphing by coaxial type plasma actuator

    Science.gov (United States)

    Toyoizumi, S.; Aono, H.; Ishikawa, H.

    2017-04-01

    The purpose of study is to achieve the fluid drag reduction of a circular disk by Dielectric Barrier Discharge Plasma Actuator (DBD-PA). We here introduced “Flow Morphing” concept that flow around the body was changed by DBD-PA jet, such as the body shape morphing. Coaxial type DBD-PA injected axisymmetric jet, generating the vortex region on the pressure side of the circular disk. The vortex generated by axisymmetric plasma jet and flow around circular disk were visualized by tracer particles method. The fluid drag was measured by compression type load cell. In addition streamwise velocity was measured by an X-type hot wire probe. The extent of fluid drag reduction by coaxial type DBD-PA jet was influenced by the volume of vortex region and the diameter of plasma electrode.

  19. Method for acquiring pressure measurements in presence of plasma-induced interference for supersonic flow control applications

    International Nuclear Information System (INIS)

    Narayanaswamy, Venkateswaran; Clemens, Noel T; Raja, Laxminarayan L

    2011-01-01

    The operation of pulsed-plasma actuators for flow control is often associated with the presence of charged species in the flow and severe electromagnetic interference with external circuitry. These effects can lead to time-resolved transducer pressure measurements that are contaminated with electromagnetic interference effects or even transducer damage due to the interaction with charged species. A new technique is developed that enables high-bandwidth pressure measurements to be made in the presence of such rapidly switched plasma actuators. The technique is applied for the specific configuration of a pulsed-plasma jet actuator (spark jet) that is used to control the unsteadiness of a shock wave/boundary layer interaction generated by a compression ramp in a Mach 3 flow. The critical component of the technique involves using a pulsed-ground electrode to drain the charged species from the plasma jet before they reach the pressure transducer. The pulsed-ground electrode was shown to drain charged species into the pulsed ground prior to interacting with the transducer, which made it possible to make measurements without damaging the transducer. The resulting signals were still contaminated by electromagnetic interference spikes and so a data-processing technique was used to remove the artifacts and recover a largely uncontaminated power spectrum. The signal processing scheme used interpolation schemes previously developed for laser Doppler velocimetry applications. The data-processing procedure is demonstrated with a benchmark case in which the electromagnetic interference was isolated from the pulsed-plasma jet actuation effect. It is shown that the data-processing procedure removed the contamination from the electromagnetic interference at all frequencies but for the pulsing frequency and its higher harmonics

  20. Experimental Investigation of Hypersonic Flow and Plasma Aerodynamic Actuation Interaction

    International Nuclear Information System (INIS)

    Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Yu Yonggui; Jie Junhun

    2013-01-01

    For hypersonic flow, it was found that the most effective plasma actuator is derived from an electromagnetic perturbation. An experimental study was performed between hypersonic flow and plasma aerodynamic actuation interaction in a hypersonic shock tunnel, in which a Mach number of 7 was reached. The plasma discharging characteristic was acquired in static flows. In a hypersonic flow, the flow field can affect the plasma discharging characteristics. DC discharging without magnetic force is unstable, and the discharge channel cannot be maintained. When there is a magnetic field, the energy consumption of the plasma source is approximately three to four times larger than that without a magnetic field, and at the same time plasma discharge can also affect the hypersonic flow field. Through schlieren pictures and pressure measurement, it was found that plasma discharging could induce shockwaves and change the total pressure and wall pressure of the flow field

  1. Plasma flow in the DIII-D divertor

    International Nuclear Information System (INIS)

    Boedo, J.A.; Porter, G.D.; Schaffer, M.J.

    1998-07-01

    Indications that flows in the divertor can exhibit complex behavior have been obtained from 2-D modeling but so far remain mostly unconfirmed by experiment. An important feature of flow physics is that of flow reversal. Flow reversal has been predicted analytically and it is expected when the ionization source arising from neutral or impurity ionization in the divertor region is large, creating a high pressure zone. Plasma flows arise to equilibrate the pressure. A radiative divertor regime has been proposed in order to reduce the heat and particle fluxes to the divertor target plates. In this regime, the energy and momentum of the plasma are dissipated into neutral gas introduced in the divertor region, cooling the plasma by collisional, radiative and other atomic processes so that the plasma becomes detached from the target plates. These regimes have been the subject of extensive studies in DIII-D to evaluate their energy and particle transport properties, but only recently it has been proposed that the energy transport over large regions of the divertor must be dominated by convection instead of conduction. It is therefore important to understand the role of the plasma conditions and geometry on determining the region of convection-dominated plasma in order to properly control the heat and particle fluxes to the target plates and hence, divertor performance. The authors have observed complex structures in the deuterium ion flows in the DIII-D divertor. Features observed include reverse flow, convective flow over a large volume of the divertor and stagnant flow. They have measured large gradients in the plasma potential across the separatrix in the divertor and determined that these gradients induce poloidal flows that can potentially affect the particle balance in the divertor

  2. Plasma flow and transport on the tokamak ISTTOK boundary plasma

    International Nuclear Information System (INIS)

    Figueiredo, H.; Silva, C.; Goncalves, B.; Duarte, P.; Fernandes, H.

    2011-01-01

    The ISTTOK boundary plasma velocity near the outer midplane is measured on the parallel and perpendicular directions in four different configurations by reversing independently the toroidal magnetic field and the plasma current directions. The parallel flow is found to not depend significantly on both the toroidal magnetic field and plasma current directions, being always directed towards the nearest limiter in the scrape-off layer. On the contrary, the perpendicular flow is found to follow the E r x B drift direction. The poloidal velocity has also been derived from the correlation of floating potential signals measured on poloidally separated probes and a good agreement with the value derived with the Gundestrup probe is found. Finally, the dynamical interplay between parallel momentum and turbulent particle flux has been investigated and a clear dynamical coupling between these quantities is found in the region inside the limiter.

  3. Dust in flowing magnetized plasma

    International Nuclear Information System (INIS)

    Pandey, Birendra P.; Samarian, Alex A.; Vladimirov, Sergey V.

    2009-01-01

    Plasma flows occur in almost every laboratory device and interactions of flowing plasmas with near-wall impurities and/or dust significantly affects the efficiency and lifetime of such devices. The charged dust inside the magnetized flowing plasma moves primarily under the influence of the plasma drag and electric forces. Here, the charge on the dust, plasma potential, and plasma density are calculated self-consistently. The electrons are assumed non-Boltzmannian and the effect of electron magnetization and electron-atom collisions on the dust charge is calculated in a self-consistent fashion. For various plasma magnetization parameters viz. the ratio of the electron and ion cyclotron frequencies to their respective collision frequencies, plasma-atom and ionization frequencies, the evolution of the plasma potential and density in the flow region is investigated. The variation of the dust charge profile is shown to be a sensitive function of plasma parameters. (author)

  4. On steady poloidal and toroidal flows in tokamak plasmas

    International Nuclear Information System (INIS)

    McClements, K. G.; Hole, M. J.

    2010-01-01

    The effects of poloidal and toroidal flows on tokamak plasma equilibria are examined in the magnetohydrodynamic limit. ''Transonic'' poloidal flows of the order of the sound speed multiplied by the ratio of poloidal magnetic field to total field B θ /B can cause the (normally elliptic) Grad-Shafranov (GS) equation to become hyperbolic in part of the solution domain. It is pointed out that the range of poloidal flows for which the GS equation is hyperbolic increases with plasma beta and B θ /B, thereby complicating the problem of determining spherical tokamak plasma equilibria with transonic poloidal flows. It is demonstrated that the calculation of the hyperbolicity criterion can be easily modified when the assumption of isentropic flux surfaces is replaced with the more tokamak-relevant one of isothermal flux surfaces. On the basis of the latter assumption, a simple expression is obtained for the variation of density on a flux surface when poloidal and toroidal flows are simultaneously present. Combined with Thomson scattering measurements of density and temperature, this expression could be used to infer information on poloidal and toroidal flows on the high field side of a tokamak plasma, where direct measurements of flows are not generally possible. It is demonstrated that there are four possible solutions of the Bernoulli relation for the plasma density when the flux surfaces are assumed to be isothermal, corresponding to four distinct poloidal flow regimes. Finally, observations and first principles-based theoretical modeling of poloidal flows in tokamak plasmas are briefly reviewed and it is concluded that there is no clear evidence for the occurrence of supersonic poloidal flows.

  5. Diagnostic methods of thermal dusty plasma flows

    International Nuclear Information System (INIS)

    Nefedov, A.P.

    1995-01-01

    The presence in the high-temperature flows of condensed disperse phase (CDP) particles may lead either to an increase of the electron number density n e if the particles assume a positive charge or to its decrease if the charge is negative. The existence of CDP also may effect on optical parameters of the thermal dusty plasma flows, on heat and radiative transfer in the plasma. The entire range of states, from a Debye plasma to a highly nonideal system of charged particles, is realized in a thermal dusty plasma under standard conditions T=2000-3000 K, n e =10 8 - 10 14 cm -3 . The advanced probe and optical diagnostic instruments are needed to study the optical and electrophysical properties of thermal dusty plasma flows. The diagnostic techniques must give the data about such parameters of gas and dispersed phase as temperatures of gas and particles, number densities of electrons, atoms and ions of alkali metals, sizes, velocities and concentrations of CDP particles. It should be noted that number density of alkali metal atoms and gas temperature may be measured by the well known full absorption and generalized reversal methods. This paper describes the probe and optical techniques for diagnostic of dusty plasma flows developed in High Energy Density Research Center of Russian Academy of Sciences. The Forward Angle Scattering Transmissometer (FAST) allows measurement of the average size (Sauter diameter), mass number density, and refractive index of particles in the 0.5-15.0 gm size range. The basis of the method is a dependence of the measured extinction of radiation upon an angular acceptance aperture of the photo detector. The FAST instrument allows one to determine the mass density and the Sauter diameter of a polydispersion of particles without a priori specification of the particle size distribution model and exact data about the article refractive index

  6. Diagnostic methods of thermal dusty plasma flows

    International Nuclear Information System (INIS)

    Nefedov, A.P.

    1995-01-01

    The presence in the high-temperature flows of condensed disperse phase (CDP) particles may lead either to an increase of the electron number density n e if the particles assume a positive charge or to its decrease if the charge is negative. The existence of CDP also may effect on optical parameters of the thermal dusty plasma flows, on heat and radiative transfer in the plasma. The entire range of states, from a Debye plasma to a highly nonideal system of charged particles, is realized in a thermal dusty plasma under standard conditions T=2000-3000 K, n e =10 8 -10 14 cm -3 . The advanced probe and optical diagnostic instruments are needed to study the optical and electrophysical properties of thermal dusty plasma flows. The diagnostic techniques must give the data about such parameters of gas and dispersed phase as temperatures of gas and particles, number densities of electrons, atoms and ions of alkali metals, sizes, velocities and concentrations of CDP particles. It should be noted that number density of alkali metal atoms and gas temperature may be measured by the well known full absorption and generalized reversal methods. This paper describes the probe and optical techniques for diagnostic of dusty plasma flows developed in High Energy Density Research Center of Russian Academy of Sciences. The Forward Angle Scattering Transmissometer (FAST) allows measurement of the average size (Sauter diameter), mass number density, and refractive index of particles in the 0.5-15.0 μm size range. The basis of the method is a dependence of the measured extinction of radiation upon an angular acceptance aperture of the photo detector. The FAST instrument allows one to determine the mass density and the Sauter diameter of a polydispersion of particles without a priori specification of the particle size distribution model and exact data about the particle refractive index

  7. Measurement of effective renal plasma flow in congestive heart failure

    International Nuclear Information System (INIS)

    Tauxe, W.N.; Dubovsky, E.V.; Mantle, J.A.; Dustan, H.P.; Logic, J.R.

    1981-01-01

    In the management of patients with congestive heart failure (CHF), it is often desirable to have precise knowledge of overall renal function, including the effective renal plasma flow (ERPF). It has long been recognized that ERPF is diminished in CHF. Since glomerular filtration rate is often decreased to a much lesser extent, other noninvasive procedures such as the measurement of creatinine clearances may not be entirely suitable. ERPF determination by the single plasma sampling (SPS) method affords a rapid, simple, noninvasive, and economical technique that is quite accurate and reproducible. A SPS method has been well-tested in patients following renal transplantation plus a wide variety of nephrological disorders. We have been concerned whether the SPS method would be valid in volume expanded patients. In 28 determinations of ERPF in patients with CHF, and in five patients who did not have CHF, we have found the SPS estimation of ERPF to yield results that are not clinically significantly different from those obtained by the detailed compartmental analysis method. The volumes of 131 I-orthoiodohippurate (OIH) distribution were found to be somewhat higher in CHF than in controls, but fractional rate constants were proportionately lower so that intercompartmental flow rates and OIH concentrations were not different from controls. Therefore, the SPS estimation of ERPF is valid in patients with CHF and may be useful in monitoring the renal effects of various hemodynamic and pharmacological interventions. (orig.)

  8. LDA measurements under plasma conditions

    International Nuclear Information System (INIS)

    Lesinski, J.; Mizera-Lesinska, B.; Fanton, J.C.; Boulos, M.I.

    1979-01-01

    A study was made of the application of Laser Doppler Anemometry (LDA) for the measurement of the fluid and particle velocities under plasma conditions. The flow configuration, is that of a dc plasma jet called the principal jet, in which an alumina powder of a mean particle diameter of 115 μm and a standard deviation of 11.3 μm was injected using a secondary jet. The plasma jet immerged from a 7.1 mm ID nozzle while that of the secondary jet was 2 nm in diameter. The secondary jet was introduced at the nozzle level of the plasma jet directed 90 0 to its axis. Details of the nozzle and the gas flow system are shown in Figure 2

  9. Energy distribution and transfer in flowing hydrogen microwave plasmas

    International Nuclear Information System (INIS)

    Chapman, R.A.

    1987-01-01

    This thesis is an experimental investigation of the physical and chemical properties of a hydrogen discharge in a flowing microwave plasma system. The plasma system is the mechanisms utilized in an electrothermal propulsion concept to convert electromagnetic energy into the kinetic energy of flowing hydrogen gas. The plasmas are generated inside a 20-cm ID resonant cavity at a driving frequency of 2.45 GHz. The flowing gas is contained in a coaxially positioned 22-mm ID quartz discharge tube. The physical and chemical properties are examined for absorbed powers of 20-100 W, pressures of 0.5-10 torr, and flow rates of 0-10,000 μ-moles/sec. A calorimetry system enclosing the plasma system to accurately measure the energy inputs and outputs has been developed. The rate of energy that is transferred to the hydrogen gas as it flows through the plasma system is determined as a function of absorbed power, pressure, and flow rate to +/-1.8 W from an energy balance around the system. The percentage of power that is transferred to the gas is found to increase with increasing flow rate, decrease with increasing pressure, and to be independent of absorbed power

  10. Measurements of the cesium flow from a surface-plasma H- ion source

    International Nuclear Information System (INIS)

    Smith, H.V.; Allison, P.W.

    1979-01-01

    A surface ionization gauge (SIG) was constructed and used to measure the Cs 0 flow rate through the emission slit of a surface-plasma source (SPS) of H - ions with Penning geometry. The equivalent cesium density in the SPS discharge is deduced from these flow measurements. For dc operation the optimum H - current occurs at an equivalent cesium density of approx. 7 x 10 12 cm -3 (corresponding to an average cesium consumption rate of 0.5 mg/h). For pulsed operation the optimum H - current occurs at an equivalent cesium density of approx. 2 x 10 13 cm -3 (1-mg/h average cesium consumption rate). Cesium trapping by the SPS discharge was observed for both dc and pulsed operation. A cesium energy of approx. 0.1 eV is deduced from the observed time of flight to the SIG. In addition to providing information on the physics of the source, the SIG is a useful diagnostic tool for source startup and operation

  11. Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma

    International Nuclear Information System (INIS)

    Dunaevsky, A.; Fisch, N.J.

    2003-01-01

    The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma

  12. Electric force on plasma ions and the momentum of the ion-neutrals flow

    Science.gov (United States)

    Makrinich, G.; Fruchtman, A.; Zoler, D.; Boxman, R. L.

    2018-05-01

    The electric force on ions in plasma and the momentum flux carried by the mixed ion-neutral flow were measured and found to be equal. The experiment was performed in a direct-current gas discharge of cylindrical geometry with applied radial electric field and axial magnetic field. The unmagnetized plasma ions, neutralized by magnetized electrons, were accelerated radially outward transferring part of the gained momentum to neutrals. Measurements were taken for various argon gas flow rates between 13 and 100 Standard Cubic Centimeter per Minute, for a discharge current of 1.9 A and a magnetic field intensity of 136 G. The plasma density, electron temperature, and plasma potential were measured at various locations along the flow. These measurements were used to determine the local electric force on the ions. The total electric force on the plasma ions was then determined by integrating radially the local electric force. In parallel, the momentum flux of the mixed ion-neutral flow was determined by measuring the force exerted by the flow on a balance force meter (BFM). The maximal plasma density was between 6 × 1010 cm-3 and 5 × 1011 cm-3, the maximal electron temperature was between 8 eV and 25 eV, and the deduced maximal electric field was between 2200 V/m and 5800 V/m. The force exerted by the mixed ion-neutral flow on the BFM agreed with the total electric force on the plasma ions. This agreement showed that it is the electric force on the plasma ions that is the source of the momentum acquired by the mixed ion-neutral flow.

  13. Spectroscopic studies of a high Mach-number rotating plasma flow

    International Nuclear Information System (INIS)

    Ando, Akira; Ashino, Masashi; Sagi, Yukiko; Inutake, Masaaki; Hattori, Kunihiko; Yoshinuma, Mikirou; Imasaki, Atsushi; Tobari, Hiroyuki; Yagai, Tsuyoshi

    2001-01-01

    Characteristics of an axially-magnetized rotating plasma are investigated by spectroscopy in the HITOP device of Tohoku University. A He plasma flows our axially and rotates azimuthally near the muzzle region of the MPD arcjet. Flow and rotational velocities and temperature of He ions and atoms are measured by Doppler shift and broadening of the HeII (γ=468.58 nm) and HeI (γ=587.56 nm) lines. Rotational velocity increases with the increase of axially-applied magnetic field strength and discharge current. As discharge current increases and mass flow rate decreases, the plasma flow velocity increases and T i increases. Ion acoustic Mach number of the plasma flow also increases, but tends to saturate at near 1. Radial profile of space potential is calculated from the obtained rotational velocity. The potential profile in the core region is parabolic corresponding to the observed rigid-body rotation of the core plasma. (author)

  14. Spectroscopic studies of a high Mach-number rotating plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Akira; Ashino, Masashi; Sagi, Yukiko; Inutake, Masaaki; Hattori, Kunihiko; Yoshinuma, Mikirou; Imasaki, Atsushi; Tobari, Hiroyuki; Yagai, Tsuyoshi [Tohoku Univ., Dept. of Electrical Engineering, Sendai, Miyagi (Japan)

    2001-07-01

    Characteristics of an axially-magnetized rotating plasma are investigated by spectroscopy in the HITOP device of Tohoku University. A He plasma flows our axially and rotates azimuthally near the muzzle region of the MPD arcjet. Flow and rotational velocities and temperature of He ions and atoms are measured by Doppler shift and broadening of the HeII ({gamma}=468.58 nm) and HeI ({gamma}=587.56 nm) lines. Rotational velocity increases with the increase of axially-applied magnetic field strength and discharge current. As discharge current increases and mass flow rate decreases, the plasma flow velocity increases and T{sub i} increases. Ion acoustic Mach number of the plasma flow also increases, but tends to saturate at near 1. Radial profile of space potential is calculated from the obtained rotational velocity. The potential profile in the core region is parabolic corresponding to the observed rigid-body rotation of the core plasma. (author)

  15. Stability of plasma cylinder with current in a helical plasma flow

    Science.gov (United States)

    Leonovich, Anatoly S.; Kozlov, Daniil A.; Zong, Qiugang

    2018-04-01

    Stability of a plasma cylinder with a current wrapped by a helical plasma flow is studied. Unstable surface modes of magnetohydrodynamic (MHD) oscillations develop at the boundary of the cylinder enwrapped by the plasma flow. Unstable eigenmodes can also develop for which the plasma cylinder is a waveguide. The growth rate of the surface modes is much higher than that for the eigenmodes. It is shown that the asymmetric MHD modes in the plasma cylinder are stable if the velocity of the plasma flow is below a certain threshold. Such a plasma flow velocity threshold is absent for the symmetric modes. They are unstable in any arbitrarily slow plasma flows. For all surface modes there is an upper threshold for the flow velocity above which they are stable. The helicity index of the flow around the plasma cylinder significantly affects both the Mach number dependence of the surface wave growth rate and the velocity threshold values. The higher the index, the lower the upper threshold of the velocity jump above which the surface waves become stable. Calculations have been carried out for the growth rates of unstable oscillations in an equilibrium plasma cylinder with current serving as a model of the low-latitude boundary layer (LLBL) of the Earth's magnetic tail. A tangential discontinuity model is used to simulate the geomagnetic tail boundary. It is shown that the magnetopause in the geotail LLBL is unstable to a surface wave (having the highest growth rate) in low- and medium-speed solar wind flows, but becomes stable to this wave in high-speed flows. However, it can remain weakly unstable to the radiative modes of MHD oscillations.

  16. On the interplay between turbulence and poloidal flows in plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Pedrosa, M.A.; Garcia-Cortes, I.

    1999-01-01

    The radial profile of Reynolds stress has been measured in the plasma boundary region of tokamaks and stellarator plasmas. The electrostatic Reynolds stress (proportional to r E-tilde θ >) shows a radial gradient close to the velocity shear layer location, showing that this mechanism can drive significant poloidal flows in the plasma boundary region of fusion plasmas. The generation of poloidal flows by Ion Bernstein Wave (IBW) is under investigation in toroidal plasmas. The radial gradient in the Reynolds stress increases with RF power and radial electric fields are modified at the RF resonance layer. (author)

  17. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    Science.gov (United States)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  18. Relaxation of potential, flows, and density in the edge plasma of Castor tokamak

    International Nuclear Information System (INIS)

    Hron, M.; Weinzettl, V.; Dufkova, E.; Duran, I.; Stoeckel, J.; Hidalgo, C.

    2004-01-01

    Decay times of plasma flows and plasma profiles have been measured after a sudden biasing switch-off in experiments on the Castor tokamak. A biased electrode has been used to polarize the edge plasma. The edge plasma potential and flows have been characterized by means of Langmuir and Mach probes, the radiation was measured using an array of bolometers. Potential profiles and poloidal flows can be well fitted by an exponential decay time in the range of 10 - 30 μs when the electrode biasing is turned off in the Castor tokamak. The radiation shows a slower time scale (about 1 ms), which is linked to the evolution in the plasma density and particle confinement. (authors)

  19. Measurements of EEDF in recombination dominated afterglow plasma

    Science.gov (United States)

    Plasil, R.; Korolov, I.; Kotrik, T.; Varju, J.; Dohnal, P.; Donko, Z.; Bano, G.; Glosik, J.

    2009-11-01

    Electron energy distribution functions (EEDF) have been measured in decaying plasma in Flowing Afterglow Langmuir Probe (FALP) experiment. The measurements have been carried out in diffusion and recombination governed plasmas used for studies of recombination of KrD+ and H3+ ions.

  20. Measurements of EEDF in recombination dominated afterglow plasma

    International Nuclear Information System (INIS)

    Plasil, R; Korolov, I; Kotrik, T; Varju, J; Dohnal, P; Glosik, J; Donko, Z; Bano, G

    2009-01-01

    Electron energy distribution functions (EEDF) have been measured in decaying plasma in Flowing Afterglow Langmuir Probe (FALP) experiment. The measurements have been carried out in diffusion and recombination governed plasmas used for studies of recombination of KrD + and H 3 + ions.

  1. Modeling plasma flow in straight and curved solenoids

    International Nuclear Information System (INIS)

    Boercker, D.B.; Sanders, D.M.; Storer, J.; Falabella, S.

    1991-01-01

    The ''flux-tube'' model originated by Morozov is a very simple and numerically efficient method for simulating ion motion in plasma filters. In order to test its utility as a design tool, we compare the predictions of the model to recent experimental measurements of plasma flow in both straight and curved solenoids

  2. Measurements of EEDF in recombination dominated afterglow plasma

    Energy Technology Data Exchange (ETDEWEB)

    Plasil, R; Korolov, I; Kotrik, T; Varju, J; Dohnal, P; Glosik, J [Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Prague (Czech Republic); Donko, Z; Bano, G, E-mail: radek.plasil@mff.cuni.c [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Budapest (Hungary)

    2009-11-15

    Electron energy distribution functions (EEDF) have been measured in decaying plasma in Flowing Afterglow Langmuir Probe (FALP) experiment. The measurements have been carried out in diffusion and recombination governed plasmas used for studies of recombination of KrD{sup +} and H{sub 3}{sup +} ions.

  3. Pyrolysis of methane in flowing microwave plasma. Pt. 1, 2

    International Nuclear Information System (INIS)

    Carmi, U.; Inor, A.A.; Avni, R.; Nickel, H.

    1978-04-01

    The flowing microwave (2.45 G Hz) plasmas of methane and methane-argon mixtures were analyzed by the electrical double floating probe system (DFPS), along the flow stream. The measured electric variables of the microwave plasma were: current, current density, electric field strength, electron temperature, positive ion and electron concentrations. They indicate an irreversible process, of the polymerization of CH 4 and CH 4 +Ar mixtures, taking place in the plasma. The polymerization process reaches its maximum 'down stream'. after the position of the microwave cavity. The polymerization was correlated to the concentration of ions and electrons in the plasma. (orig.) [de

  4. Two-dimensional magnetic field evolution measurements and plasma flow speed estimates from the coaxial thruster experiment

    International Nuclear Information System (INIS)

    Black, D.C.; Mayo, R.M.; Gerwin, R.A.; Schoenberg, K.F.; Scheuer, J.T.; Hoyt, R.P.; Henins, I.

    1994-01-01

    Local, time-dependent magnetic field measurements have been made in the Los Alamos coaxial thruster experiment (CTX) [C. W. Barnes et al., Phys. Fluids B 2, 1871 (1990); J. C. Fernandez et al., Nucl. Fusion 28, 1555 (1988)] using a 24 coil magnetic probe array (eight spatial positions, three axis probes). The CTX is a magnetized, coaxial plasma gun presently being used to investigate the viability of high pulsed power plasma thrusters for advanced electric propulsion. Previous efforts on this device have indicated that high pulsed power plasma guns are attractive candidates for advanced propulsion that employ ideal magnetohydrodynamic (MHD) plasma stream flow through self-formed magnetic nozzles. Indirect evidence of magnetic nozzle formation was obtained from plasma gun performance and measurements of directed axial velocities up to v z ∼10 7 cm/s. The purpose of this work is to make direct measurement of the time evolving magnetic field topology. The intent is to both identify that applied magnetic field distortion by the highly conductive plasma is occurring, and to provide insight into the details of discharge evolution. Data from a magnetic fluctuation probe array have been used to investigate the details of applied magnetic field deformation through the reconstruction of time-dependent flux profiles. Experimentally observed magnetic field line distortion has been compared to that predicted by a simple one-dimensional (1-D) model of the discharge channel. Such a comparison is utilized to estimate the axial plasma velocity in the thruster. Velocities determined in this manner are in approximate agreement with the predicted self-field magnetosonic speed and those measured by a time-of-flight spectrometer

  5. Measurement of air entrainment in plasma jets

    International Nuclear Information System (INIS)

    Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.

    1990-01-01

    The concentration and temperature of air entrained into argon and helium plasma jets has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The argon plasma flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition of turbulence occurs, air is rapidly mixed into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number. In contrast, the helium plasma flow field never exceeds a Reynolds number of 200 and remains laminar. The entrainment process in this case is controlled by molecular diffusion rather than turbulent mixing. 9 refs., 5 figs., 1 tab

  6. Jet flow and premixed jet flame control by plasma swirler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang, E-mail: ligang@iet.cn [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang, Xi [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zhao, Yujun [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Liu, Cunxi [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Qi [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xu, Gang; Liu, Fuqiang [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-04-04

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design. - Highlights: • The discharge does not ignite the mixture nor does it induce flashback. • The prominent advantage of this novel plasma swirler is its swirl number adjustable without any mechanical movement. • The frequency of the plasma swirler is adjustable. • The plasma swirler can be used as an oscillator to the reactants. • The plasma swirler can be used alone or combine with other traditional swirlers.

  7. Effect of Equilibrium Flow on Plasma Parameters

    International Nuclear Information System (INIS)

    Mukhopadhyay, S.; Lahiri, S.; Sakanaka, P.H.; Dasgupta, B.

    2003-01-01

    The transition to high confinement modes have been identified with the occurrence of strong shear flow near the plasma boundary. Plasma flow has also been associated with various instabilities, heating and other physical processes. As a result, it has become very important to study the effect of such flows on various plasma parameters. In this paper, we present the numerical solution of plasma equilibrium with incompressible toroidal and poloidal flows in several magnetic confinement configurations including tokamaks. The code, which was reported in the last conference, has been used to solve the problem in both circular and D-shaped devices. A parametric study on the generation of shear flow due to radial electric fields has been carried out. Through this study, it has been possible to generate plasma equilibria having sharp pressure gradients which are remarkably close to those reported in various H-mode experiments. The effects of flow on reverse shear equilibria and on the position of the magnetic axis has been studied. Finally, a detailed study has been carried out to understand the effect of flows on important plasma parameters, such as the poloidal flux function, β, energy confinement time

  8. Turbulence measurements in fusion plasmas

    International Nuclear Information System (INIS)

    Conway, G D

    2008-01-01

    Turbulence measurements in magnetically confined toroidal plasmas have a long history and relevance due to the detrimental role of turbulence induced transport on particle, energy, impurity and momentum confinement. The turbulence-the microscopic random fluctuations in particle density, temperature, potential and magnetic field-is generally driven by radial gradients in the plasma density and temperature. The correlation between the turbulence properties and global confinement, via enhanced diffusion, convection and direct conduction, is now well documented. Theory, together with recent measurements, also indicates that non-linear interactions within the turbulence generate large scale zonal flows and geodesic oscillations, which can feed back onto the turbulence and equilibrium profiles creating a complex interdependence. An overview of the current status and understanding of plasma turbulence measurements in the closed flux surface region of magnetic confinement fusion devices is presented, highlighting some recent developments and outstanding problems.

  9. Laboratory Observation of a Plasma-Flow-State Transition from Diverging to Stretching a Magnetic Nozzle.

    Science.gov (United States)

    Takahashi, Kazunori; Ando, Akira

    2017-06-02

    An axial magnetic field induced by a plasma flow in a divergent magnetic nozzle is measured when injecting the plasma flow from a radio frequency (rf) plasma source located upstream of the nozzle. The source is operated with a pulsed rf power of 5 kW, and the high density plasma flow is sustained only for the initial ∼100  μsec of the discharge. The measurement shows a decrease in the axial magnetic field near the source exit, whereas an increase in the field is detected at the downstream side of the magnetic nozzle. These results demonstrate a spatial transition of the plasma-flow state from diverging to stretching the magnetic nozzle, where the importance of both the Alfvén and ion Mach numbers is shown.

  10. Plasma flow in toroidal systems with a separatrix

    International Nuclear Information System (INIS)

    Gribkov, V.M.; Morozov, D.Kh.; Pogutse, O.P.

    1984-01-01

    A hydrodynamic plasma flow in toroidal systems is considered. Rlasma flow lines for various magnetic configurations are calculated. A particular attention is given to studying plasma flow in configurations with two magnetic a axes and a separatrix. The flow picture i the toroidal case is shown to qualita ity to penetrate through the separatrix - the latter becomes ''perforated''. Th he pictkre of these flows is calculated. The plasma diffusion coefficient with account for the separatrix is calculated and is shown not to turn into the infin nity in the toroidal case as well. The plasma flow is analytically considered in the model with distributed current as well as in the model with current conce entrated at the oroidal system axis. In the first case the existence of ''stagnant'' regions near the magnetic axis is established from which the plasma a does not flow out

  11. A high sensitivity momentum flux measuring instrument for plasma thruster exhausts and diffusive plasmas.

    Science.gov (United States)

    West, Michael D; Charles, Christine; Boswell, Rod W

    2009-05-01

    A high sensitivity momentum flux measuring instrument based on a compound pendulum has been developed for use with electric propulsion devices and radio frequency driven plasmas. A laser displacement system, which builds upon techniques used by the materials science community for surface stress measurements, is used to measure with high sensitivity the displacement of a target plate placed in a plasma thruster exhaust. The instrument has been installed inside a vacuum chamber and calibrated via two different methods and is able to measure forces in the range of 0.02-0.5 mN with a resolution of 15 microN. Measurements have been made of the force produced from the cold gas flow and with a discharge ignited using argon propellant. The plasma is generated using a Helicon Double Layer Thruster prototype. The instrument target is placed about 1 mean free path for ion-neutral charge exchange collisions downstream of the thruster exit. At this position, the plasma consists of a low density ion beam (10%) and a much larger downstream component (90%). The results are in good agreement with those determined from the plasma parameters measured with diagnostic probes. Measurements at various flow rates show that variations in ion beam velocity and plasma density and the resulting momentum flux can be measured with this instrument. The instrument target is a simple, low cost device, and since the laser displacement system used is located outside the vacuum chamber, the measurement technique is free from radio frequency interference and thermal effects. It could be used to measure the thrust in the exhaust of other electric propulsion devices and the momentum flux of ion beams formed by expanding plasmas or fusion experiments.

  12. Plasma actuators for bluff body flow control

    Science.gov (United States)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  13. Relaxed states with plasma flow

    International Nuclear Information System (INIS)

    Avinash, K.; Taylor, J.B.

    1991-01-01

    In the theory of relaxation, a turbulent plasma reaches a state of minimum energy subject to constant magnetic helicity. In this state the plasma velocity is zero. Attempts have been made by introducing a number of different constraints, to obtain relaxed states with plasma flow. It is shown that these alternative constraints depend on two self-helicities, one for ions, and one for electrons. However, whereas there are strong arguments for the effective invariance of the original magnetic-helicity, these arguments do not apply to the self-helicities. Consequently the existence of relaxed states with flow remains in doubt. (author)

  14. Non-equilibrium in flowing atmospheric plasmas

    International Nuclear Information System (INIS)

    Haas, J.C.M. de.

    1986-01-01

    This thesis deals with the fundamental aspects of two different plasmas applied in technological processes. The first one is the cesium seeded argon plasma in a closed cycle Magnetohydrodynamic (MHD) generator, the second is the thermal argon plasma in a cascade arc with an imposed flow. In Chapter 2 the influence of non-equilibrium on the mass and energy balances of a plasma is worked out. The general theory presented there can be applied to both the plasma in an MHD generator and to the cascade arc with imposed flow. Introductions to these plasmas are given in the Chapters 3 and 6 respectively. These chapters are both followed by two chapters which treat the theoretical and the experimental investigations. The results are summarized in Chapter 9. (Auth.)

  15. Relaxation of plasma potential and poloidal flows in the boundary of tokamak plasmas

    International Nuclear Information System (INIS)

    Hron, M.; Duran, I.; Stoeckel, J.; Hidalgo, C.; Gunn, J.

    2003-01-01

    The relaxation times of plasma parameters after a sudden change of electrode voltage have been measured in the plasma boundary during polarization experiments on the CASTOR tokamak (R = 0.4 m, a = 75 mm, B t = 1 T, I p ∼ 9 kA, q a ∼ 10). The time evolution of the floating potential after the biasing voltage switch-off can be well fitted by an exponential decay with characteristic time in the range of 10 - 20 μs. The poloidal flow shows a transient behaviour with a time scale of about 10 - 30 μs. These time scales are smaller than the expected damping time based on neoclassical parallel viscosity (which is in the range of 100 νs) and atomic physics via charge exchange (in the range of 100 - 1000 νs). But, they are larger than the correlation time of plasma turbulence (about 5 μs). These findings suggest that anomalous damping rate mechanisms for radial electric fields and poloidal flows may play a role in the boundary of tokamak plasmas. (authors)

  16. Plasma flow velocity measurements using a modulated Michelson interferometer

    International Nuclear Information System (INIS)

    Howard, J.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (orig.)

  17. Plasma-liquid system with reverse vortex flow of 'tornado' type (TORNADO-LE)

    International Nuclear Information System (INIS)

    Nedybalyuk, O.A.; Chernyak, V.Ya.; Olszewski, S.V.

    2010-01-01

    The results of experimental investigations of the plasma in plasma-liquid system with reverse vortex flow of 'tornado' type are presented. Volt-ampere characteristic of discharge in the current range from 200 to 400 mA were measured. Emission spectra of plasma in range from 200 to 1100 nm were measured. Excitation temperatures (electronic T e * , vibrational T v * and rotational T r * ) were obtained. Emission spectra of hydroxyl OH were calculated.

  18. Plasma flow velocity measurements using a modulated Michelson interferometer

    NARCIS (Netherlands)

    Howard, J.; Meijer, F. G.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (C) 1997 Elsevier Science S.A.

  19. Plasma Flows in Crossed Magnetic and Electric Fields

    International Nuclear Information System (INIS)

    Belikov, A.G.

    2005-01-01

    The effect of the magnitude and direction of an external electric field on the plasma flowing through a magnetic barrier is studied by numerically solving two-fluid MHD equations. The drift velocity of the plasma flow and the distribution of the flow electrons over transverse velocities are found to depend on the magnitude and direction of the electric field. It is shown that the direction of the induced longitudinal electric field is determined by the direction of the external field and that the electric current generated by the plasma flow significantly disturbs the barrier field

  20. Measurements of the asymmetric dynamic sheath around a pulse biased sphere immersed in flowing metal plasma

    Science.gov (United States)

    Wu, Hongchen; Anders, André

    2008-08-01

    A long-probe technique was utilized to record the expansion and retreat of the dynamic sheath around a spherical substrate immersed in pulsed cathode arc metal plasma. Positively biased, long cylindrical probes were placed on the side and downstream of a negatively pulsed biased stainless steel sphere of 1 in. (25.4 mm) diameter. The amplitude and width of the negative high voltage pulses (HVPs) were 2 kV, 5 kV, 10 kV, and 2 µs, 4 µs, 10 µs, respectively. The variation of the probe (electron) current during the HVP is a direct measure for the sheath expansion and retreat. Maximum sheath sizes were determined for the different parameters of the HVP. The expected rarefaction zone behind the biased sphere (wake) due to the fast plasma flow was clearly established and quantified.

  1. Stationary shear flows in CGL anisotropic toroidal plasmas

    International Nuclear Information System (INIS)

    Pastukhov, V.P.; Ilgisonis, V.I.

    1996-01-01

    Recently a general structure of stationary shear flows in toroidal plasmas was obtained in the frame of ideal isotropic-pressure MHD model. The structure of the stationary plasma flows was shown to be determined by a hidden symmetry of MHD equations inherent in the toroidal systems with nested magnetic surfaces. However, the characteristic frequencies of the stationary plasma motion can considerably exceed the collisional frequencies in real plasma experiments. In this case the CGL collisionless MHD model seems to be more adequate than the simplified isotropic-pressure MHD model to describe the stationary plasma flows. In this paper we have generalized our approach to analyze the stationary plasma flows in the frame of the collisionless CGL model. We have found again that the hidden symmetry inherent in the toroidal topology results in two integral invariants which depend on two independent surface functions. The structure of stationary flows for CGL model is still the same as for isotropic MHD, however, the pressure tensor components satisfy a appreciably modifies the steady state force-balance equation. These results are applied to analyze the generalized equilibrium in axisymmetric (tokamak-like) magnetic confinement systems

  2. Generator of the low-temperature heterogeneous plasma flow

    Science.gov (United States)

    Yusupov, D. I.; Gadzhiev, M. Kh; Tyuftyaev, A. S.; Chinnov, V. F.; Sargsyan, M. A.

    2018-01-01

    A generator of low-temperature dc plasma with an expanding channel of an output electrode for gas-thermal spraying was designed and constructed. The delivery of the sprayed powder into the cathode and anode arc-binding zones or into the plasma jet below the anode binding was realized. The electrophysical characteristics of both the plasma torch and the heterogeneous plasma flow with Al2O3 powder are studied. It is shown that the current-voltage characteristic (CVC) of a plasma torch depends on the gas flow rate. If the flow rate varies from 1 to 3 g/s, the falling CVC becomes gradually increasing. The speed and temperature of the sprayed powder are determined.

  3. Electric and thermodynamic properties of plasma flows created by a magnetoplasma compressor

    International Nuclear Information System (INIS)

    Puric, J; Dojcinovic, I P; Astashynski, V M; Kuraica, M M; Obradovic, B M

    2004-01-01

    A magnetoplasma compressor of compact geometry (MPC-CG) with a semi-transparent electrode system that operates in the ion current transfer regime was constructed and studied. The electric and thermodynamic parameters of the discharge and the plasma flow created in different gases and their mixtures (hydrogen, nitrogen, argon and Ar + 3% H 2 ) have been measured to optimize the working conditions within the 100-3000 Pa pressure range for input energy up to 6.4 kJ. A special construction of the accelerator electrode system shielded by the self-magnetic field results in protection from erosion, which is the main cause of the high current cut-off in conventional plasma accelerators. It was found that the compression plasma flow velocity, electron density and temperature predominantly depend on the energy conversion rate from the energy supply to the plasma, since the current cut-off is avoided. The maximum energy conversion rate for MPC-CG was found when operating in hydrogen. The plasma flow velocity and electron density maximum values are measured close to 100 km s -1 and 10 17 cm -3 , respectively, for input energy of 6.4 kJ at 1000 Pa pressure in hydrogen. Our results appear in good agreement with existing theoretical and experimental data

  4. Understanding the SOL flow in L-mode plasma on divertor tokamaks, and its influence on the plasma transport

    International Nuclear Information System (INIS)

    Asakura, Nobuyuki

    2007-01-01

    Significant progress has been made in understanding the driving mechanisms in SOL mass transport along the magnetic field lines (SOL flow). SOL flow measurements by Mach probes and impurity plume have been performed in L-mode plasma at various poloidal locations in divertor tokamaks. All results showed common SOL flow patterns: subsonic flow with parallel Mach number (M parallel ) of 0.2-1 was generated from the Low-Field-Side (LFS) SOL to the High-Field-Side (HFS) divertor for the ion ∇B drift towards the divertor. The SOL flow pattern was formed mainly by LFS-enhanced asymmetry in diffusion and by classical drifts. In addition, divertor detachment and/or intense puffing-and-pump enhanced the HFS SOL flow. Most codes have incorporated drift effects, and asymmetric diffusion was modelled to simulate the fast SOL flow. Influences of the fast SOL flow on the impurity flow in the SOL, shielding from core plasma, and deposition profile, were directly observed in experiments

  5. Individual renal plasma flow determination in 2 minutes

    International Nuclear Information System (INIS)

    Schlegel, J.U.; Hamway, S.A.

    1976-01-01

    A method is described for determining effective renal plasma flow, using the renal counts 1 to 2 minutes after injection and applying background subtraction as a ratio to the total amount of radioactivity injected intravenously with appropriate correction for kidney depth. It appears that this simple approach for determination of effective renal plasma flow within a matter of 2 minutes is accurate and reliable, and should be useful for a number of applications when it is important to determine total and individual renal plasma flow. The approach is recommended as a screening procedure in lieu of the determination of blood urea nitrogen and serum creatinine, with the additional advantages of gross morphology and determination of individual renal plasma flow in an absolute as well as relative manner

  6. Measurements of the asymmetric dynamic sheath around a pulse biased sphere immersed in flowing metal plasma

    International Nuclear Information System (INIS)

    Wu Hongchen; Anders, Andre

    2008-01-01

    A long-probe technique was utilized to record the expansion and retreat of the dynamic sheath around a spherical substrate immersed in pulsed cathode arc metal plasma. Positively biased, long cylindrical probes were placed on the side and downstream of a negatively pulsed biased stainless steel sphere of 1 in. (25.4 mm) diameter. The amplitude and width of the negative high voltage pulses (HVPs) were 2 kV, 5 kV, 10 kV, and 2 μs, 4 μs, 10 μs, respectively. The variation of the probe (electron) current during the HVP is a direct measure for the sheath expansion and retreat. Maximum sheath sizes were determined for the different parameters of the HVP. The expected rarefaction zone behind the biased sphere (wake) due to the fast plasma flow was clearly established and quantified.

  7. Advanced plasma flow simulations of cathodic-arc and ferroelectric plasma sources for neutralized drift compression experiments

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2008-07-01

    Full Text Available Large-space-scale and long-time-scale plasma flow simulations are executed in order to study the spatial and temporal evolution of plasma parameters for two types of plasma sources used in the neutralized drift compression experiment (NDCX. The results help assess the charge neutralization conditions for ion beam compression experiments and can be employed in more sophisticated simulations, which previously neglected the dynamical evolution of the plasma. Three-dimensional simulations of a filtered cathodic-arc plasma source show the coupling efficiency of the plasma flow from the source to the drift region depends on geometrical factors. The nonuniform magnetic topology complicates the well-known general analytical considerations for evaluating guiding-center drifts, and particle-in-cell simulations provide a self-consistent evaluation of the physics in an otherwise challenging scenario. Plasma flow profiles of a ferroelectric plasma source demonstrate that the densities required for longitudinal compression experiments involving ion beams are provided over the drift length, and are in good agreement with measurements. Simulations involving azimuthally asymmetric plasma creation conditions show that symmetric profiles are nevertheless achieved at the time of peak on-axis plasma density. Also, the ferroelectric plasma expands upstream on the thermal expansion time scale, and therefore avoids the possibility of penetration into the acceleration gap and transport sections, where partial neutralization would increase the beam emittance. Future experiments on NDCX will investigate the transverse focusing of an axially compressing intense charge bunch to a sub-mm spot size with coincident focal planes using a strong final-focus solenoid. In order to fill a multi-tesla solenoid with the necessary high-density plasma for beam charge neutralization, the simulations predict that supersonically injected plasma from the low-field region will penetrate and

  8. Kelvin-Helmholtz instability in a bounded plasma flow

    International Nuclear Information System (INIS)

    Burinskaya, T. M.

    2008-01-01

    Kelvin-Helmholtz instability in a three-layer plane geometry is investigated theoretically. It is shown that, in a three-layer system (in contrast to the traditionally considered case in which instability develops at the boundary between two plasma flows), instability can develop at an arbitrary ratio of the plasma flow velocity to the ion-acoustic velocity. Perturbations with wavelengths on the order of the flow thickness or longer can increase even at a zero temperature. The system can also be unstable against long-wavelength perturbations if the flow velocity at one of the boundaries is lower than the sum of the Alfven velocities in the flow and the ambient plasma. The possibility of applying the results obtained to interpret the experimental data acquired in the framework of the CLUSTER multisatellite project is discussed. It follows from these data that, in many cases, the propagation of an accelerated particle flow in the plasma-sheet boundary layer of the Earth's magnetotail is accompanied by the generation of magnetic field oscillations propagating with a velocity on the order of the local Alfven velocity.

  9. Plasma flow healing of magnetic islands in stellarators

    International Nuclear Information System (INIS)

    Hegna, C. C.

    2012-01-01

    Recent experiments from the large helical device (LHD) demonstrate a correlation between the “healing” of vacuum magnetic islands in stellarators and changes in the plasma flow. A model explaining this phenomenon is developed based on self-consistent torque balance and island evolution equations. In conventional stellarators, neoclassical flow damping physics plays an important role in establishing the flow profiles. The balance of neoclassical damping and cross-field viscosity produces a radial boundary layer for the plasma rotation profile outside the separatrix of a locked magnetic island. The width of this boundary layer decreases as the plasma becomes less collisional. Associated with these flow effects are plasma currents flowing in the island region that attempt to suppress island formation. These currents are enhanced as the collisionality drops making magnetic island healing occur more readily in high temperature conventional stellarators. The analytic theory produces a critical β for healing that scales monotonically with collisionality and is in qualitative agreement with LHD observations.

  10. Transport hysteresis and zonal flow stimulation in magnetized plasmas

    Science.gov (United States)

    Gravier, E.; Lesur, M.; Reveille, T.; Drouot, T.; Médina, J.

    2017-12-01

    A hysteresis in the relationship between zonal flows and electron heating is observed numerically by using gyrokinetic simulations in fusion plasmas. As the electron temperature increases, a first transition occurs, at a given electron/ion temperature ratio, above which zonal flows are much weaker than before the transition, leading to a poorly confined plasma. Beyond this transition, even if the electron temperature is lowered to a moderate value, the plasma fails to recover a dynamic state with strong zonal flows. Then, as the electron temperature decreases further, a new transition appears, at a temperature lower than the first transition, below which the zonal flows are stronger than they were initially. The confinement of the plasma and the heat flux are thus found to be sensitive to the history of the magnetized plasma. These transitions are associated with large exchanges of energy between the modes corresponding to instabilities ( m> 0 ) and zonal flows ( m = 0 ). We also observe that up to the first transition it is possible to use a control method to stimulate the appearance of zonal flows and therefore the confinement of the plasma. Beyond that transition, this control method is no longer effective.

  11. Asymmetry reversal of ion collection by mach probes in flowing unmagnetized plasmas

    International Nuclear Information System (INIS)

    Ko, E; Hershkowitz, N

    2006-01-01

    Measurements of ion current in flowing unmagnetized plasmas were performed with planar and spherical Mach probes in two different devices, one a dc multi-dipole plasma device for subsonic flow within a presheath region and the other a double plasma device for supersonic flow. Asymmetry reversal, which is higher ion current to the downstream side of the probe compared with the upstream side current, was observed for high probe bias compared with the electron temperature, relatively low ion drift velocity and Debye length comparable to probe radius. These data are in qualitative agreement with a recent numerical calculation by Hutchinson. As suggested by Hutchinson, it was found that the current ratio depended on the plasma parameters, especially for finite Debye length and high probe bias. Asymmetry reversal emphasizes the lack of validity of using the current ratio except for narrow parameter ranges. This study is the first experiment to demonstrate the non-intuitive phenomenon predicted by Hutchinson's numerical calculation

  12. Measurement of the complete core plasma flow across the LOC-SOC transition at ASDEX Upgrade

    Science.gov (United States)

    Lebschy, A.; McDermott, R. M.; Angioni, C.; Geiger, B.; Prisiazhniuk, D.; Cavedon, M.; Conway, G. D.; Dux, R.; Dunne, M. G.; Kappatou, A.; Pütterich, T.; Stroth, U.; Viezzer, E.; the ASDEX Upgrade Team

    2018-02-01

    A newly installed core charge exchange recombination spectroscopy (CXRS) diagnostic at ASDEX Upgrade (AUG) enables the evaluation of the core poloidal rotation (upol ) through the inboard-outboard asymmetry of the toroidal rotation with an accuracy of 0.5 to 1 km s-1 . Using this technique, the total plasma flow has been measured in Ohmic L-mode plasmas across the transition from the linear to saturated ohmic confinement (LOC-SOC) regimes. The core poloidal rotation of the plasma around mid-radius is found to be always in the ion diamagnetic direction, in disagreement with neoclassical (NC) predictions. The edge rotation is found to be electron-directed and consistent with NC codes. This measurement provides as well the missing ingredient to evaluate the core E×B velocity (uE×B ) from data only, which can then be compared to measurements of the perpendicular velocity of the turbulent fluctuations (u\\perp ) to gain information on the turbulent phase velocity (vph ). The non neoclassical upol from CXRS leads to good agreement between uE×B and u\\perp indicating that vph is small and at similar values as found with gyrokinetic simulations. Moreover, the data shows a shift of vph in the ion-diamagnetic direction at the edge after the transition from LOC to SOC consistent with a change in the dominant turbulence regime. The upgrade of the core CXRS system provides as well a deeper insight into the intrinsic rotation. This paper shows that the reversal of the core toroidal rotation occurs clearly after the LOC-SOC transition and concomitant with the peaking of the electron density.

  13. Sheared-flow induced confinement transition in a linear magnetized plasma

    Science.gov (United States)

    Zhou, S.; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Carter, T. A.; Vincena, S.; Friedman, B.; Schaffner, D.

    2012-01-01

    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential (δn /n~eδφ/kTe~0.5) are observed at the plasma edge, accompanied by a large density gradient (Ln=|∇lnn |-1~2cm) and shearing rate (γ ~300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (Vbias) on the obstacle and the axial magnetic field (Bz) strength. In cases with low Vbias and large Bz, improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by E ×B drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller Bz, large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m =1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge.

  14. Sheared-flow induced confinement transition in a linear magnetized plasma

    International Nuclear Information System (INIS)

    Zhou, S.; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Carter, T. A.; Vincena, S.; Friedman, B.; Schaffner, D.

    2012-01-01

    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential (δn/n∼eδφ/kT e ∼0.5) are observed at the plasma edge, accompanied by a large density gradient (L n =∇lnn -1 ∼2cm) and shearing rate (γ∼300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (V bias ) on the obstacle and the axial magnetic field (B z ) strength. In cases with low V bias and large B z , improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by ExB drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller B z , large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m=1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge.

  15. Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

    Science.gov (United States)

    Yambe, Kiyoyuki; Saito, Hidetoshi

    2017-12-01

    When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

  16. Drag Reduction by Laser-Plasma Energy Addition in Hypersonic Flow

    International Nuclear Information System (INIS)

    Oliveira, A. C.; Minucci, M. A. S.; Toro, P. G. P.; Chanes, J. B. Jr; Myrabo, L. N.

    2008-01-01

    An experimental study was conducted to investigate the drag reduction by laser-plasma energy addition in a low density Mach 7 hypersonic flow. The experiments were conducted in a shock tunnel and the optical beam of a high power pulsed CO 2 TEA laser operating with 7 J of energy and 30 MW peak power was focused to generate the plasma upstream of a hemispherical model installed in the tunnel test section. The non-intrusive schlieren optical technique was used to visualize the effects of the energy addition to hypersonic flow, from the plasma generation until the mitigation of the shock wave profile over the model surface. Aside the optical technique, a piezoelectric pressure transducer was used to measure the impact pressure at stagnation point of the hemispherical model and the pressure reduction could be observed

  17. Compartment model for the measurement of the effective renal plasma flow by radionuclidenephrography

    International Nuclear Information System (INIS)

    Ryabov, S.I.; Degtyareva, O.A.

    1988-01-01

    By reason of model ideas on hippuran kinetics radionuclide nephrograms were split up into a renal component and a component of the tissue background. New indices for the evaluation of renal function symmetry were proposed comprising the proportional determination of the effective renal plasma flow as well as of the symmetrical blood flow. For early diagnosis of latent renal dysfunction a new index is proposed characterizing the excretory renal transport as to local renal blood supply. Empirical indices of 120 patients suffering from chronic glomerulonephritis and pyelonephritis, resp., are stated

  18. Development of plasma diagnostics technologies - Measurement of transport= parameters in tokamak edge plasma by using electric transport probes

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyu Sun; Chang, Do Hee; Sim, Yeon Gun; Kim, Jin Hee [Hanyang University, Seoul (Korea, Republic of)

    1995-08-01

    Electric transport probe system is developed for the measurement of electron temperature, floating potential, plasma density and flow velocity of= edge plasmas in the KT-2 medium size tokamak. Experiments have been performed in KT-1 small size tokamak. Electric transport probe is composed of a single probe(SP) and a Mach probe (MP). SP is used for the measurements of electron density, floating potential, and plasma density and measured values are {approx} 3*10{sup 11}/cm{sup -3}, -20 volts, 15 {approx} 25 eV. For the most discharges, respectively. MP is for the measurements of toroidal(M{sub T}) and poloidal(M{sub P}) flow velocities, and density, which are M{sub T} {approx_equal} .0.85, M{sub P} {approx_equal}. 0.17, n. {approx_equal} 2.1*10{sup 11} cm{sup -3}, respectively. A triple probe is also developed for the direct reading of T{sub e} and n{sub e}, and is used for DC, RF, and RF+DC plasma in APL of Hanyang university. 38 refs., 36 figs. (author)

  19. Laboratory simulation of energetic flows of magnetospheric planetary plasma

    International Nuclear Information System (INIS)

    Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Boyarintsev, E L; Zakharov, Yu P; Prokopov, P A; Ponomarenko, A G

    2017-01-01

    Dynamic interaction of super-sonic counter-streaming plasmas moving in dipole magnetic dipole is studied in laboratory experiment. First, a quasi-stationary flow is produced by plasma gun which forms a magnetosphere around the magnetic dipole. Second, explosive plasma expanding from inner dipole region outward is launch by laser beams focused at the surface of the dipole cover. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. Probe measurements showed that far from the initially formed magnetosphere laser plasma carries within itself a magnetic field of the same direction but order of magnitude larger in value than the vacuum dipole field at considered distances. Because no compression of magnetic field at the front of laser plasma was observed, the realized interaction is different from previous experiments and theoretical models of laser plasma expansion into uniform magnetized background. It was deduced based on the obtained data that laser plasma while expanding through inner magnetosphere picks up a magnetized shell formed by background plasma and carries it for large distances beyond previously existing magnetosphere. (paper)

  20. Plasma flow in a pressure pulsed argon cascade arc

    NARCIS (Netherlands)

    de Haas, J.C.M.; Bol, L.; Kroesen, G.M.W.; Timmermans, C.J.; Timmermans, C.J.

    1985-01-01

    Flowing thermal plasmas are frequently used e . g. in welding, cutting, plasma deposition and testing materials at high temperatures . In most of the applications the geometry is complex . In the cascade arc the argon plasma flows through a straight circular channel with a constant area. The study

  1. Analysis of the flow structure of a turbulent thermal plasma jet

    International Nuclear Information System (INIS)

    Spores, R.A.

    1989-01-01

    The goal of this research project is to attain a better understanding of the fluid mechanics associated with the high temperature jet of a thermal plasma torch. The analysis of a plasma, which has the ability to vaporize anything placed inside it without proper cooling, presents a unique research challenge. Several types of non-intrusive diagnostic techniques has been used to examine the jet from different perspectives. To actually map out the mean gas velocities and turbulence intensities throughout the jet, laser Doppler anemometry has been employed. The plasma gas and entrained air him been seeded separately in order to conditionally sample the two fluids and attain information about the gas mixing process. Both radial and axial turbulence levels have been measured in order to analyze the non-isotropic nature of the jet. A parabolic numerical code has been modified and compared with the obtained experimental results. A new diagnostic technique for plasma torches, which involves the spectral analysis of voltage, optical (temperature), and acoustical (pressure) fluctuations, has been implemented. The acoustical spectrum can provide information about the existence of coherent structures in the flow while the cross correlation of the acoustical signal with the voltage fluctuations can tell one to what extent perturbations of the internal arc affect the external flow. Since temperature is a scalar that is dependent on the flow field, observing temperature fluctuations can likewise help one to understand the mechanics of the flow. Flow visualization of the plasma jet using a high speed video camera has also been undertaken in order to better understand the entrainment process

  2. Effect of toroidal plasma flow and flow shear on global MHD modes

    International Nuclear Information System (INIS)

    Chu, M.S.; Greene, J.M.; Jensen, T.H.; Miller, R.L.; Bondeson, A.; Johnson, R.W.; Mauel, M.E.

    1995-01-01

    The effect of a subsonic toroidal flow on the linear magnetohydrodynamic stability of a tokamak plasma surrounded by an external resistive wall is studied. A complex non-self-adjoint eigenvalue problem for the stability of general kink and tearing modes is formulated, solved numerically, and applied to high β tokamaks. Results indicate that toroidal plasma flow, in conjunction with dissipation in the plasma, can open a window of stability for the position of the external wall. In this window, stable plasma beta values can significantly exceed those predicted by the Troyon scaling law with no wall. Computations utilizing experimental data indicate good agreement with observations

  3. Anisotropic plasma with flows in tokamak: Steady state and stability

    International Nuclear Information System (INIS)

    Ilgisonis, V.I.

    1996-01-01

    An adequate description of equilibrium and stability of anisotropic plasma with macroscopic flows in tokamaks is presented. The Chew-Goldberger-Low (CGL) approximation is consistently used to analyze anisotropic plasma dynamics. The admissible structure of a stationary flow is found to be the same as in the ideal magnetohydrodynamics with isotropic pressure (MHD), which means an allowance for the same relabeling symmetry as in ideal MHD systems with toroidally nested magnetic surfaces. A generalization of the Grad-Shafranov equation for the case of anisotropic plasma with flows confined in the axisymmetric magnetic field is derived. A variational principle was obtained, which allows for a stability analysis of anisotropic pressure plasma with flows, and takes into account the conservation laws resulting from the relabeling symmetry. This principle covers the previous stability criteria for static CGL plasma and for ideal MHD flows in isotropic plasma as well. copyright 1996 American Institute of Physics

  4. Flow speed measurement using two-point collective light scattering

    International Nuclear Information System (INIS)

    Heinemeier, N.P.

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au)

  5. Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator

    Directory of Open Access Journals (Sweden)

    Şanlısoy A.

    2013-04-01

    Full Text Available In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

  6. Measurement of OH free radical in magnetized sheet plasma crossed with vertical gas-flow by laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Tonegawa, Akira; Takatori, Masahiko; Kobayashi, Yukihiro; Kawamura, Kazutaka; Takayama, Kazuo

    1997-01-01

    We demonstrated the production of OH free radicals in an argon magnetized sheet plasma crossed with vertical gas-flow mixed with an oxygen gas O 2 and a hydrogen gas H 2 . The density and the rotational-vibrational temperature of the OH free radicals were measured by a laser-induced fluorescence (LIF). The density of OH free radicals increases with increasing O 2 gas-flow, while the high energy part of the electron-energy-distribution-function f e (E) above 8 eV decreases. These results suggest the high energy part of f e (E) is contributed to the dissociation of O 2 and the production of OH free radicals. (author)

  7. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.

    Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  8. Reconstruction of the ion plasma parameters from the current measurements: mathematical tool

    Directory of Open Access Journals (Sweden)

    E. Séran

    2003-05-01

    Full Text Available Instrument d’Analyse du Plasma (IAP is one of the instruments of the newly prepared ionospheric mission Demeter. This analyser was developed to measure flows of thermal ions at the altitude of ~ 750 km and consists of two parts: (i retarding potential analyser (APR, which is utilised to measure the energy distribution of the ion plasma along the sensor look direction, and (ii velocity direction analyser (ADV, which is used to measure the arrival angle of the ion flow with respect to the analyser axis. The necessity to obtain quick and precise estimates of the ion plasma parameters has prompted us to revise the existing mathematical tool and to investigate different instrumental limitations, such as (i finite angular aperture, (ii grid transparency, (iii potential depression in the space between the grid wires, (iv losses of ions during their passage between the entrance diaphragm and the collector. Simple analytical expressions are found to fit the currents, which are measured by the APR and ADV collectors, and show a very good agreement with the numerical solutions. It was proven that the fitting of the current with the model functions gives a possibility to properly resolve even minor ion concentrations and to find the arrival angles of the ion flow in the multi-species plasma. The discussion is illustrated by an analysis of the instrument response in the ionospheric conditions which are predicted by the International Reference Ionosphere (IRI model.Key words. Ionosphere (plasma convection; instruments and techniques – Space plasma physics (experimental and mathematical techniques

  9. A simple estimation of the renal plasma flow

    International Nuclear Information System (INIS)

    Shinpo, Takako

    1987-01-01

    The renal plasma flow was determined conventionally by the excretive ratio to urine using a 131 I-Hippuran renogram. In this report, we proposed the renal clearance, the product of the disappearance rate coefficient and the maximum counts of the bladder, for the simple quantitative value of renal plasma flow. The disappearance rate coefficient was calculated by approximating the exponential function of the initial slope from the disappearance curve of the heart. The renal clearances was compared with the renal plasma flow calculated by the conventional method. The results gave a high correlation coefficient of r = 0.91. The renal clearances can be calculated easily and it offers useful renogram information. (author)

  10. Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

    Science.gov (United States)

    Thomas, Flint; Kozlov, Alexey

    2008-11-01

    The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

  11. Two-Phase Flow Regimes and Discharge Characteristics of a Plasma Electrohydrodynamic Atomization

    International Nuclear Information System (INIS)

    Sun Ming; Borocilo, D.; Harvel, G. D.; Chang, J. S.; Ibe, M.; Matsubara, H.; Hirata, H.; Fanson, P.

    2011-01-01

    Experimental investigation was conducted to study the flow regimes and discharge characteristics of plasma electrohydrodynamic atomization (EHDA) for decane (C 10 H 22 ) under pulsed applied negative voltage. The experimental parameters were set as the flow rate of decane from 0 mL/min to 10 mL/min and the DC charging voltage from DC 0 V to 12 V with a pulse repetition rates of 200 Hz. The flow regime of decane was observed and the volume-to-electrical charge ratio was measured. Unlike a conventional EHDA system, the results show that a corona discharge was initiated at the edge of the hollow electrode at a specific corona on-set voltage of -17 kV or -20 kV in the case with or without decane flow, respectively. This phenomenon was defined as plasma EHDA.

  12. Optimization of plasma flow parameters of the magnetoplasma compressor

    International Nuclear Information System (INIS)

    Dojcinovic, I P; Kuraica, M M; Obradovc, B M; Cvetanovic, N; Puric, J

    2007-01-01

    Optimization of the working conditions of the magnetoplasma compressor (MPC) has been performed through analysing discharge and compression plasma flow parameters in hydrogen, nitrogen and argon at different pressures. Energy conversion rate, volt-ampere curve exponent and plasma flow velocities have been studied to optimize the efficiency of energy transfer from the supply source to the plasma. It has been found that the most effective energy transfer from the supply to the plasma is in hydrogen as a working gas at 1000 Pa pressure. It was found that the accelerating regime exists for hydrogen up to 3000 Pa pressures, in nitrogen up to 2000 Pa and in argon up to 1000 Pa pressure. At higher pressures MPC in all the gases works in the decelerating regime. At pressures lower than 200 Pa, high cathode erosion is observed. MPC plasma flow parameter optimization is very important because this plasma accelerating system may be of special interest for solid surface modification and other technology applications

  13. Plasma extraction by centrifugo-pneumatically induced gating of flow

    International Nuclear Information System (INIS)

    Burger, Robert; Ducrée, Jens; Reis, Nuno; Da Fonseca, João Garcia

    2013-01-01

    We present a novel valving mechanism to implement plasma extraction from whole blood on a centrifugal microfluidic ‘lab-on-a-disc’ platform. The new scheme is based on pressure-induced deflection of a liquid membrane which gates the centrifugally driven flow through a microfluidic structure. Compared to conventional concepts such as capillary burst valves, siphons or sacrificial materials, the valving structure presented here is represented by a compact, small-footprint design which obviates the need for (local) surface functionalization or hybrid materials integration, thus significantly reducing the complexity (and hence cost) of manufacture. As a pilot study of this new centrifugal flow control element, we demonstrate here the efficient separation of metered plasma from whole blood. While the flow is stopped, blood is separated into plasma and its cellular constituents by centrifugally induced sedimentation. After completion, the flow resumes by elevating the spinning frequency, providing up to 80% of the original plasma content to an overflow chamber within a short, 2 min interval. The amount of residual cells in the plasma amounts to less than 20 cells μl −1 . (paper)

  14. Measurement of the dynamo effect in a plasma

    International Nuclear Information System (INIS)

    Ji, H.; Prager, S.C.; Almagri, A.F.; Sarff, J.S.; Hirano, Y.; Toyama, H.

    1995-11-01

    A series of the detailed experiments has been conducted in three laboratory plasma devices to measure the dynamo electric field along the equilibrium field line (the α effect) arising from the correlation between the fluctuating flow velocity and magnetic field. The fluctuating flow velocity is obtained from probe measurement of the fluctuating E x B drift and electron diamagnetic drift. The three major findings are (1) the α effect accounts for the dynamo current generation, even in the time dependence through a ''sawtooth'' cycle; (2) at low collisionality the dynamo is explained primarily by the widely studied pressureless Magnetohydrodynamic (MHD) model, i.e., the fluctuating velocity is dominated by the E x B drift; (3) at high collisionality, a new ''electron diamagnetic dynamo'' is observed, in which the fluctuating velocity is dominated by the diamagnetic drift. In addition, direct measurements of the helicity flux indicate that the dynamo activity transports magnetic helicity from one part of the plasma to another, but the total helicity is roughly conserved, verifying J.B. Taylor's conjecture

  15. Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, N.

    2002-01-01

    SOL plasma flow plays an important role in the plasma transport along the field lines, and influences control of the divertor plasma and impurity ions. Recently, mechanisms producing the SOL flow such as drifts produced by electric field and pressure gradient are pointed out. In JT-60U, three reciprocating Mach probes were installed at the high-field-side (HFS) baffle, low-field-side (LFS) midplane and just below the X-point. The measurements of the SOL flow and plasma profiles both at the HFS and LFS, for the first time, found out the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the separatrix of the HFS and LFS. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included. SOL particle fluxes towards the HFS and LFS divertors were, for the first time, evaluated. Important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions with intense gas puff and divertor pump (puff and pump), were investigated. (author)

  16. Statistical study of high-latitude plasma flow during magnetospheric substorms

    Directory of Open Access Journals (Sweden)

    G. Provan

    2004-11-01

    Full Text Available We have utilised the near-global imaging capabilities of the Northern Hemisphere SuperDARN radars, to perform a statistical superposed epoch analysis of high-latitude plasma flows during magnetospheric substorms. The study involved 67 substorms, identified using the IMAGE FUV space-borne auroral imager. A substorm co-ordinate system was developed, centred on the magnetic local time and magnetic latitude of substorm onset determined from the auroral images. The plasma flow vectors from all 67 intervals were combined, creating global statistical plasma flow patterns and backscatter occurrence statistics during the substorm growth and expansion phases. The commencement of the substorm growth phase was clearly observed in the radar data 18-20min before substorm onset, with an increase in the anti-sunward component of the plasma velocity flowing across dawn sector of the polar cap and a peak in the dawn-to-dusk transpolar voltage. Nightside backscatter moved to lower latitudes as the growth phase progressed. At substorm onset a flow suppression region was observed on the nightside, with fast flows surrounding the suppressed flow region. The dawn-to-dusk transpolar voltage increased from ~40kV just before substorm onset to ~75kV 12min after onset. The low-latitude return flow started to increase at substorm onset and continued to increase until 8min after onset. The velocity flowing across the polar-cap peaked 12-14min after onset. This increase in the flux of the polar cap and the excitation of large-scale plasma flow occurred even though the IMF Bz component was increasing (becoming less negative during most of this time. This study is the first to statistically prove that nightside reconnection creates magnetic flux and excites high-latitude plasma flow in a similar way to dayside reconnection and that dayside and nightside reconnection, are two separate time-dependent processes.

  17. Measurements of plasma rotation in an axially magnetized MPD arc-jet

    Energy Technology Data Exchange (ETDEWEB)

    Tobari, Hiroyuki; Ashino, Masashi; Yoshino, Kyohei; Sagi, Yukiko; Yoshinuma, Mikirou; Hattori, Kunihiko; Ando, Akira; Inutake, Masaaki [Department of Electrical Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi (Japan)

    2001-01-24

    Characteristics of an axially magnetized MPD (magneto-plasma-dynamic) arcjet plasma are investigated by spectroscopy on the HITOP (High density of Tohoku Plasma) device in Tohoku University. Plasma flow and rotational velocity and temperature of He ion and atom near the muzzle region of MPD arcjet are measured by Doppler shift and broadening of the HeI ({lambda}=578.56 nm) and HeII ({lambda}=468.58 nm) lines. From the measured radial profile of rotational velocity and temperature of He ion, the radial profiles of electrical field and space potential are calculated and it has been found that the potential profile in the core region is parabolic, which shows the plasma rotates as a rigid body. (author)

  18. Three-dimensional flow measurements induced from serpentine plasma actuators in quiescent air

    International Nuclear Information System (INIS)

    Durscher, R J; Roy, S

    2012-01-01

    This paper presents three-dimensional flow measurements performed on a dielectric barrier discharge (DBD) actuator with the electrodes in a serpentine design. Such a configuration induces a local pinching and a local spreading of the fluid as one follows along the span of the actuator. In this work two different variations on the serpentine configuration are evaluated: one constructed from patterned circular arcs and one from patterned rectangles. The influence of applied voltage is studied for the former case. To quantify these effects stereo particle image velocimetry (PIV) is used to generate time averaged, spatially resolved measurements of the detailed flow structure. The three components of the velocity vector are measured along spanwise and streamwise cuts. These slices are then reconstructed to provide a three-dimensional view of the induced flow field. The results for the induced flow fields are also compared with stereo-PIV measurements made on a standard linear DBD actuator. A truly three-dimensional induced flow field was observed as a result of the serpentine configuration. These designs could be beneficial for rapid mixing of the local fluid. (paper)

  19. Flow speed measurement using two-point collective light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Heinemeier, N.P

    1998-09-01

    Measurements of turbulence in plasmas and fluids using the technique of collective light scattering have always been plagued by very poor spatial resolution. In 1994, a novel two-point collective light scattering system for the measurement of transport in a fusion plasma was proposed. This diagnostic method was design for a great improvement of the spatial resolution, without sacrificing accuracy in the velocity measurement. The system was installed at the W7-AS steallartor in Garching, Germany, in 1996, and has been operating since. This master thesis is an investigation of the possible application of this new method to the measurement of flow speeds in normal fluids, in particular air, although the results presented in this work have significance for the plasma measurements as well. The main goal of the project was the experimental verification of previous theoretical predictions. However, the theoretical considerations presented in the thesis show that the method can only be hoped to work for flows that are almost laminar and shearless, which makes it of very small practical interest. Furthermore, this result also implies that the diagnostic at W7-AS cannot be expected to give the results originally hoped for. (au) 1 tab., 51 ills., 29 refs.

  20. Plasma flow discharge researches at the PIRIT-2000 facility

    International Nuclear Information System (INIS)

    Popkov, N.F.; Ryaslov, E.A.; Kargin, V.I.; Pikar', A.S.; Vorontsov, V.I.; Kotel'nikov, D.V.; Melkozerov, A.V.

    1996-01-01

    Investigation of a plasma flow switch at the PIRIT-2000 fast operating capacitor bank is reported. The maximum current of the plasma flow discharge (PFD) reaches 5 MA, the current rise time being as low as 100 ns. The magnetic field strength of the plasma flow switch (0.15 T) is about 15 times higher than that of the plasma erosion switch used earlier. Both magnetic probe and optical methods were used in the experiments. From the magnetic probes data the propagating velocity of a current carrying shell (205 cm/s) has been derived, while the optical method is used for determining the velocity of a glowing plasma layer. At varying the operation delay in the range 2-10 s the PFD load current rise time increases up to 150-200 ns, the prepulse increment reaching its maximum at the delays higher than 6 s. (J.U.). 5 figs., 5 refs

  1. Plasma flow discharge researches at the PIRIT-2000 facility

    Energy Technology Data Exchange (ETDEWEB)

    Popkov, N F; Ryaslov, E A; Kargin, V I; Pikar` , A S; Vorontsov, V I; Kotel` nikov, D V; Melkozerov, A V [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    Investigation of a plasma flow switch at the PIRIT-2000 fast operating capacitor bank is reported. The maximum current of the plasma flow discharge (PFD) reaches 5 MA, the current rise time being as low as 100 ns. The magnetic field strength of the plasma flow switch (0.15 T) is about 15 times higher than that of the plasma erosion switch used earlier. Both magnetic probe and optical methods were used in the experiments. From the magnetic probes data the propagating velocity of a current carrying shell (205 cm/s) has been derived, while the optical method is used for determining the velocity of a glowing plasma layer. At varying the operation delay in the range 2-10 s the PFD load current rise time increases up to 150-200 ns, the prepulse increment reaching its maximum at the delays higher than 6 s. (J.U.). 5 figs., 5 refs.

  2. Generation of zonal flows in rotating fluids and magnetized plasmas

    DEFF Research Database (Denmark)

    Juul Rasmussen, J.; Garcia, O.E.; Naulin, V.

    2006-01-01

    The spontaneous generation of large-scale flows by the rectification of small-scale turbulent fluctuations is of great importance both in geophysical flows and in magnetically confined plasmas. These flows regulate the turbulence and may set up effective transport barriers. In the present....... The analogy to large-scale flow generation in drift-wave turbulence dynamics in magnetized plasma is briefly discussed....

  3. Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, N.; Takenaga, H.; Sakurai, S.

    2003-01-01

    The measurements of the SOL flow and plasma profiles both at the high-field-side (HFS) and low field- side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇β drift direction towards the divertor. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)

  4. Driving mechanism of SOL plasma flow an effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, Nobuyuki; Takenaga, H.; Sakurai, S.

    2003-01-01

    The measurements of the scrape-off layer(SOL) flow and plasma profiles both at the high-field-side (HFS) and low-field-side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇B drift direction towards the divertor, Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)

  5. Direct measurement of the plasma response to electrostatic ion waves

    International Nuclear Information System (INIS)

    Sarfaty, M.; DeSouza-Machado, S.; Skiff, F.

    1995-01-01

    Plasma wave-wave and wave-particle interactions are studied in a linear magnetized plasma. The relatively quiet plasma is produced by an argon gas-discharge. The plasma density is n e ≅ 10 9 cm -3 and the electron/ion temperatures are T e ≅ 5eV and T i = 0.05eV. A grid and a four ring antenna, both mounted on a scanning carriage, are used to launch electrostatic ion waves in the plasma. Laser Induced Fluorescence measurements of both the linear and the nonlinear plasma response to the wave fields are presented. The Vlasov-Poisson equations are used to explain the measured zero, first and second order terms of the ion distribution function in the presence of wave fields. In addition to the broadening (heating) of the ion distribution as the authors increase the wave amplitudes, induced plasma flows are observed both along and across the magnetic field

  6. A small spacecraft for multipoint measurement of ionospheric plasma

    Science.gov (United States)

    Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.

    2017-07-01

    Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.

  7. Nonlinear vortex structures and Rayleigh instability condition in shear flow plasmas

    International Nuclear Information System (INIS)

    Haque, Q.; Saleem, H.; Mirza, A.M.

    2009-01-01

    Full text: It is shown that the shear flow produced by externally applied electric field can unstable the drift waves. Due to shear flow, the Rayleigh instability condition is modified, which is obtained for both electron-ion and electron-positron-ion plasmas. These shear flow driven drift waves can be responsible for large amplitude electrostatic fluctuations in tokamak edges. In the nonlinear regime, the stationary structures may appear in electron-positron-ion plasmas similar to electron-ion plasmas. The nonlinear vortex structures like counter rotating dipole vortices and vortex chains can be formed with the aid of special type of shear flows. The positrons can be used as a probe in laboratory plasmas, which make it a multi-component plasma. The presence of positrons in electron-ion plasma system can affect the speed and amplitude of the nonlinear vortex structures. This investigation can have application in both laboratory and astrophysical plasmas. (author)

  8. Interaction of counter-streaming plasma flows in dipole magnetic field

    OpenAIRE

    Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Prokopov, P A; Boyarintsev, E L; Zakharov, Yu P; Ponomarenko, A G

    2017-01-01

    Transient interaction of counter-streaming super-sonic plasma flows in dipole magnetic dipole is studied in laboratory experiment. First quasi-stationary flow is produced by teta-pinch and forms a magnetosphere around the magnetic dipole while laser beams focused at the surface of the dipole cover launch second explosive plasma expanding from inner dipole region outward. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. ...

  9. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    International Nuclear Information System (INIS)

    Michael, Clive; Howard, John

    2000-01-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  10. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    Energy Technology Data Exchange (ETDEWEB)

    Michael, Clive; Howard, John [Australian National Univ., Plasma Research Laboratory, Canberra (Australia)

    2000-03-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  11. Thin film plasma coatings from dielectric free-flowing materials

    International Nuclear Information System (INIS)

    Timofeeva, L.A.; Katrich, S.A.; Solntsev, L.A.

    1994-01-01

    Fabrication of thin film plasma coatings from insulating free-flowing materials is considered. Molybdenum-tart ammonium coating of 3...5 μ thickness deposited on glassy carbon, aluminium, silicon, nickel, cast iron and steel substrates in 'Bulat-ZT' machine using insulating free-flowing materials cathod was found to form due to adsorption, absorption and dissuasion processes. The use of insulating free-flowing materials coatings allow to exclude pure metals cathods in plasma-plating process

  12. Electrical Processes in a Flowing Plasma with Cold Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Distefano, E.; Fraidenraich, N. [Facultad de Ciencias Fisicas y Matematicas, University of Chile, Santiago (Chile)

    1968-11-15

    The voltage-current characteristics of a flowing plasma between two electrodes is of interest for MHD power generation because of the high voltage drop necessary to make a current flow through the cool boundary layer of the plasma, lowering the efficiency of the MHD generator when the duct walls are cooled. The V-I characteristics are obtained for a combustion driven shock-tube generated plasma, and the voltage distribution is measured by probes inserted across the plasma. The gas used is argon and the plasma parameters are: T = 9000 Degree-Sign K, p = 130 mmHg, u = 2500 m/sec, n{sub e} = 1.60 x 10{sup 15} cm{sup -3}. The probe technique has allowed experimental confirmation of the high voltage drop obtained in the vicinity of the cathode. A theoretical model has been set up in order to explain the main features of this phenomenon. The model considers the voltage drop along the following regions: the turbulent boundary layer and the viscous sublayer. The structure of the first two regions are taken into account according to the Coles transformation theory. The model considers three fluids, ions, electrons and neutrals: the mass and momentum particle conservation together with the Poisson equation and continuity of electric current allows us to set up a system of four differential equations with four unknowns. Pair production is taken into account in order to explain the necessary change over from electron current in the main body of the plasma to the predominantly ionic current in the neighbourhood of the cathode wall. Numerical computation of the system of equations has been done and the main features of the experimental results are explained. (author)

  13. Plasma actuators for active flow control based on a glow discharge

    International Nuclear Information System (INIS)

    Kühn, M.; Kühn-Kauffeldt, M.; Schein, J.; Belinger, A.

    2017-01-01

    In this work a glow discharge based active flow control for high flow velocities and low Reynolds numbers is presented. Unlike common plasma actuators such as dielectric barrier discharge (DBD) or spark jets, this actuator uses small impulse bits at frequencies. The actuator is optimized for frequencies up to 40 kHz to counter Tollmien Schlichting wave effects and so reduce overall air foil drag. Several measurements to prove the non-eroding effect of the actuator and the electrical properties were performed. It was found that the actuator is capable of operating at high frequencies without measurable erosion. (paper)

  14. Study on dynamics of the influence exerted by plasma on gas flow field in non-thermal atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Qaisrani, M. Hasnain; Xian, Yubin, E-mail: yubin.xian@hotmail.com; Li, Congyun; Pei, Xuekai; Ghasemi, Maede; Lu, Xinpei [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2016-06-15

    In this paper, first, steady state of the plasma jet at different operating conditions is investigated through Schlieren photography with and without applying shielding gas. Second, the dynamic process for the plasma impacting on the gas flow field is studied. When the discharge is ignited, reduction in laminar flow occurs. However, when the gas flow rate is too low or too high, this phenomenon is not obvious. What is more, both frequency and voltage have significant impact on the effect of plasma on the gas flow, but the former is more significant. Shielding gas provides a curtain for plasma to propagate further. High speed camera along with Schlieren photography is utilized to study the impact of plasma on the gas flow when plasma is switched on and off. The transition of the gas flow from laminar to turbulent or vice versa happens right after the turbulent front. It is concluded that appearance and propagation of turbulence front is responsible for the transition of the flow state.

  15. Critical gradients and plasma flows in the edge plasma of Alcator C-Moda)

    Science.gov (United States)

    Labombard, B.; Hughes, J. W.; Smick, N.; Graf, A.; Marr, K.; McDermott, R.; Reinke, M.; Greenwald, M.; Lipschultz, B.; Terry, J. L.; Whyte, D. G.; Zweben, S. J.; Alcator C-Mod Team

    2008-05-01

    Recent experiments have led to a fundamental shift in our view of edge transport physics; transport near the last-closed flux surface may be more appropriately described in terms of a critical gradient phenomenon rather than a diffusive and/or convective paradigm. Edge pressure gradients, normalized by the square of the poloidal magnetic field strength, appear invariant in plasmas with the same normalized collisionality, despite vastly different currents and magnetic fields—a behavior that connects with first-principles electromagnetic plasma turbulence simulations. Near-sonic scrape-off layer (SOL) flows impose a cocurrent rotation boundary condition on the confined plasma when B ×∇B points toward the active x-point, suggesting a link to the concomitant reduction in input power needed to attain high-confinement modes. Indeed, low-confinement mode plasmas are found to attain higher edge pressure gradients in this configuration, independent of the direction of B, evidence that SOL flows may affect transport and "critical gradient" values in the edge plasma.

  16. Miniaturized heat flux sensor for high enthalpy plasma flow characterization

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent; Battaglia, Jean-Luc; Lohlec, Stefan; Jullien, Pierre; Van Ootegemd, Bruno; Couzie, Jacques; Lasserre, Jean-Pierre

    2013-01-01

    An improved miniaturized heat flux sensor is presented aiming at measuring extreme heat fluxes of plasma wind tunnel flows. The sensor concept is based on an in-depth thermocouple measurement with a miniaturized design and an advanced calibration approach. Moreover, a better spatial estimation of the heat flux profile along the flow cross section is realized with this improved small sensor design. Based on the linearity assumption, the heat flux is determined using the impulse response of the sensor relating the heat flux to the temperature of the embedded thermocouple. The non-integer system identification (NISI) procedure is applied that allows a calculation of the impulse response from transient calibration measurements with a known heat flux of a laser source. The results show that the new sensor leads to radially highly resolved heat flux measurement for a flow with only a few centimetres in diameter, the so far not understood non-symmetric heat flux profiles do not occur with the new sensor design. It is shown that this former effect is not a physical effect of the flow, but a drawback of the classical sensor design. (authors)

  17. Measuring Plasma Formation Field Strength and Current Loss in Pulsed Power Diodes

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Mark D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Patel, Sonal G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Falcon, Ross Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cartwright, Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Kiefer, Mark L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Cuneo, Michael E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Radiographic Technologies Dept.; Maron, Yitzhak [Weizmann Inst. of Science, Rehovot (Israel)

    2017-11-01

    This LDRD investigated plasma formation, field strength, and current loss in pulsed power diodes. In particular the Self-Magnetic Pinch (SMP) e-beam diode was studied on the RITS-6 accelerator. Magnetic fields of a few Tesla and electric fields of several MV/cm were measured using visible spectroscopy techniques. The magnetic field measurements were then used to determine the current distribution in the diode. This distribution showed that significant beam current extends radially beyond the few millimeter x-ray focal spot diameter. Additionally, shielding of the magnetic field due to dense electrode surface plasmas was observed, quantified, and found to be consistent with the calculated Spitzer resistivity. In addition to the work on RITS, measurements were also made on the Z-machine looking to quantify plasmas within the power flow regions. Measurements were taken in the post-hole convolute and final feed gap regions on Z. Dopants were applied to power flow surfaces and measured spectroscopically. These measurements gave species and density/temperature estimates. Preliminary B-field measurements in the load region were attempted as well. Finally, simulation work using the EMPHASIS, electromagnetic particle in cell code, was conducted using the Z MITL conditions. The purpose of these simulations was to investigate several surface plasma generations models under Z conditions for comparison with experimental data.

  18. Marangoni flows induced by atmospheric-pressure plasma jets

    International Nuclear Information System (INIS)

    Berendsen, C W J; Van Veldhuizen, E M; Kroesen, G M W; Darhuber, A A

    2015-01-01

    We studied the interaction of atmospheric-pressure plasma jets of Ar or air with liquid films of an aliphatic hydrocarbon on moving solid substrates. The hydrodynamic jet-liquid interaction induces a track of lower film thickness. The chemical plasma-surface interaction oxidizes the liquid, leading to a local increase of the surface tension and a self-organized redistribution of the liquid film. We developed a numerical model that qualitatively reproduces the formation, instability and coarsening of the flow patterns observed in the experiments. Monitoring the liquid flow has potential as an in-situ, spatially and temporally resolved, diagnostic tool for the plasma-liquid surface interaction. (paper)

  19. Measurements of flows in the DIII-D divertor by Mach probes

    International Nuclear Information System (INIS)

    Boedo, J.A.; Lehmer, R.; Moyer, R.A.; Watkins, J.G.; Porter, G.D.; Evans, T.E.; Leonard, A.W.; Schaffer, M.J.

    1998-06-01

    First measurements of Mach number of background plasma in the DIII-D divertor are presented in conjunction with temperature T e and density n e using a fast scanning probe array. To validate the probe measurements, the authors compared the T e , n e and J sat data to Thomson scattering data and find good overall agreement in attached discharges and some discrepancy for T e and n e in detached discharges. The discrepancy is mostly due to the effect of large fluctuations present during detached plasmas on the probe characteristic; the particle flux is accurately measured in every case. A composite 2-D map of measured flows is presented for an ELMing H-mode discharge and they focus on some of the details. They have also documented the temperature, density and Mach number in the private flux region of the divertor and the vicinity of the X-point, which are important transition regions that have been little studied or modeled. Background parallel plasma flows and electric fields in the divertor region show a complex structure

  20. Investigations on interactions between the flowing liquid lithium limiter and plasmas

    International Nuclear Information System (INIS)

    Ren, J.; Zuo, G.Z.; Hu, J.S.; Sun, Z.; Li, J.G.; Zakharov, L.E.; Ruzic, D.N.; Xu, W.Y.

    2016-01-01

    Two different designs of flowing liquid lithium limiter were first tested for power exhaust and particle removal in HT-7 in 2012 autumn campaign. During the experiments, the reliability and compatibility of the limiters within Tokamak were experimentally demonstrated, and some positive results were achieved. It was found that the flowing liquid lithium limiter was effective for suppressing H concentration and led to a low ratio of H/(H + D). O impurity was slightly decreased by using limiters as well as when using a Li coating. A significant increase of the wall retention ratio was also observed which resulted from the outstanding D particles pumping ability of flowing liquid lithium limiters. The strong interaction between plasma and lithium surface could cause lithium ejection into plasma and lead to disruptions. The stable plasmas produced by uniform Li flow were in favor of lithium control. While the limiters were applied with a uniform Li flow, the normal plasma was easy to be obtained, and the energy confinement time increased from ∼0.025 s to 0.04 s. Furthermore, it was encouraging to note that the application of flowing liquid lithium limiters could further improve the confinement of plasma by ∼10% on the basis of Li coating. These remarkable results will help for the following design of flowing liquid lithium limiter in EAST to improve the plasma operation.

  1. Control of open end plasma flow utilizing orbital stochasticity

    International Nuclear Information System (INIS)

    Hojo, Hitoshi

    1995-01-01

    It has been known that the control of plasma outside the confinement region of diverter plasma and others in a magnetic field confinement device is very important for improveing the confinement of bulk plasma. The control of plasma outside a confinement region bears two roles, one is the reduction of the thermal load on a diverter plate and others due to the plasma particles lost from the confinement region, and another is the restriction of the back flow of cold plasma and impurities generated outside the confinement region to a bulk plasma region. In this study, the new method of controlling plasma outside a confinement region called magnetic diverter is considered. To the plasma particles advancing along magnetic force lines, the reflection and capture of the plasma particles occur in the region of orbital stochasticity, and the thermal load on an end plate and the reverse flow to a bulk plasma region are restricted. The numerical computation model used regarding the particle control utilizing the orbital stochasticity and the results of calculating the orbit of plasma particles in a magnetic field are reported. (K.I.)

  2. Ideal stability of cylindrical plasma in the presence of mass flow

    International Nuclear Information System (INIS)

    Bondeson, A.; Iacono, R.

    1988-11-01

    The ideal stability of cylindrical plasma with mass flows is investigated using the guiding centre plasma (GCP) model of Grad. For rotating plasmas, the kinetic treatment of the parallel motion in GCP gives significantly different results than fluid models, where the pressures are obtained from equations of state. In particular, GCP removes the resonance with slow magnetoacoustic waves and the loss of stability that results in magnetohydrodynamics (MHD) for near-soni flows. Because of the strong kinetic damping of the sound waves in an isothermal plasma, the slow waves have little influence on plasma stability in GCP at low β. In the large aspect ratio, low-β tokamak ordering, Alfvenic flows are needed to change the ideal GCP stability significantly. At lowest order in the inverse aspect ratio, flow can be favorable or unfavorable for stability of local modes depending on the profiles, but external kinks are always destilized by flow if the velocity vanishes at the edge. For high-β, reversed field pinch equilibria, numerical computations show that flow can be stabilizing for local modes, but external modes are destabilized by flow. It is shown that in three dimensions, the MHD equilibrium problem becomes hyperbolic for arbitrarily small flows across the magnetic field, whereas in GCP the equilibrium remains elliptic for sub-Alfvenic flows. (author) 7 figs., 1 tab, 32 refs

  3. Cross-field flow and electric potential in a plasma slab

    Directory of Open Access Journals (Sweden)

    J. De Keyser

    2013-08-01

    Full Text Available We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.

  4. Cross-tail velocity component in the plasma sheet fast flows

    Directory of Open Access Journals (Sweden)

    N. P. Dmitrieva

    2008-06-01

    Full Text Available The flux transfer in the magnetotail plasma sheet is mainly provided by the tail-aligned fast plasma flows (Bursty Bulk Flows – BBFs. In this paper we study the events with a large cross-tail velocity component, including their occurrence and relationship to the standard BBFs. We found out that a significant part of large Vy events are a subgroup connected with the BBFs propagation. The maximal deviation of the velocity vector from the X direction (about 40–50 degrees, on average is observed near the BBFs' leading front in the sheath, where the fast flow interacts with surrounding plasma. The average variation of the velocity direction in the vicinity of the BBF resembles a plasma vortex. Our results support the model, in which the BBF represents a polarized, bubble-like flux tube, propagating through the plasma sheet.

  5. Correcting for particle size effects on plasma actuator particle image velocimetry measurements

    Science.gov (United States)

    Masati, A.; Sedwick, R. J.

    2018-01-01

    Particle image velocimetry (PIV) is often used to characterize plasma actuator flow, but particle charging effects are rarely taken into account. A parametric study was conducted to determine the effects of particle size on the velocity results of plasma actuator PIV experiments. Results showed that smaller particles more closely match air flow velocities than larger particles. The measurement uncertainty was quantified by deconvolving the particle image diameter from the correlation diameter. The true air velocity was calculated by linearly extrapolating to the zero-size particle diameter.

  6. Control of supersonic axisymmetric base flows using passive splitter plates and pulsed plasma actuators

    Science.gov (United States)

    Reedy, Todd Mitchell

    An experimental investigation evaluating the effects of flow control on the near-wake downstream of a blunt-based axisymmetric body in supersonic flow has been conducted. To better understand and control the physical phenomena that govern these massively separated high-speed flows, this research examined both passive and active flow-control methodologies designed to alter the stability characteristics and structure of the near-wake. The passive control investigation consisted of inserting splitter plates into the recirculation region. The active control technique utilized energy deposition from multiple electric-arc plasma discharges placed around the base. The flow-control authority of both methodologies was evaluated with experimental diagnostics including particle image velocimetry, schlieren photography, surface flow visualization, pressure-sensitive paint, and discrete surface pressure measurements. Using a blowdown-type wind tunnel reconstructed specifically for these studies, baseline axisymmetric experiments without control were conducted for a nominal approach Mach number of 2.5. In addition to traditional base pressure measurements, mean velocity and turbulence quantities were acquired using two-component, planar particle image velocimetry. As a result, substantial insight was gained regarding the time-averaged and instantaneous near-wake flow fields. This dataset will supplement the previous benchmark point-wise laser Doppler velocimetry data of Herrin and Dutton (1994) for comparison with new computational predictive techniques. Next, experiments were conducted to study the effects of passive triangular splitter plates placed in the recirculation region behind a blunt-based axisymmetric body. By dividing the near-wake into 1/2, 1/3, and 1/4 cylindrical regions, the time-averaged base pressure distribution, time-series pressure fluctuations, and presumably the stability characteristics were altered. While the spatial base pressure distribution was

  7. Spectroscopic measurement of the electric field in a helium plasma jet

    NARCIS (Netherlands)

    Hofmans, M.; Sobota, A.

    2017-01-01

    The electric field in a plasma jet is measured spectroscopically utilizing the Stark-effect. A cold atmospheric pressure helium plasma jet is used, which operates at a μs-pulsed applied voltage of 6 kV, a frequency of 5 kHz and with a helium flow of 1.5 slm. Due to the electric field in the jet, the

  8. Transport in zonal flows in analogous geophysical and plasma systems

    Science.gov (United States)

    del-Castillo-Negrete, Diego

    1999-11-01

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

  9. Modelling of flow stabilization by the swirl of a peripheral flow as applied to plasma reactors

    International Nuclear Information System (INIS)

    Volchkov, E.P.; Lebedev, V.P.; Terekhov, V.I.; Shishkin, N.E.

    2000-01-01

    The gas-swirl stabilization of plasma jets is one of effective methods of its retention in the near-axial area of channels in generators of low-temperature plasma. Except the effect of gas-dynamic compression, the peripheral swirl allows to solve another urgent problem - to protect the reactor walls from the heat influence of the plasma jet. Swirl flows are also used for the flow structure formation and control of the heat and gas-dynamic characteristics of different power devices and apparatuses, using high-temperature working media: in swirl furnaces and burners, in aviation engines, etc. Investigations show that during swirl stabilization the gas-dynamic structure of the flow influences significantly the spatial stability of the plasma column and its characteristics

  10. Heat flow during sawtooth collapse in tokamak plasmas

    International Nuclear Information System (INIS)

    Hanada, Kazuaki

    1994-01-01

    Heat flow during sawtooth collapse was studied on the WT-3 tokamak by using temporal evolution of soft X-ray intensity profile in the poloidal cross section in a lower hybrid current driven plasma as well as an electron cyclotron heated plasma. Two phase in sawtooth collapses were observed. In the first phases, the hottest spot that is the peak of the soft X-ray distribution approaches the inversion surface and heat flows out through a narrow gate on the inversion surface. In the second phase, the hottest spot stays on the inversion surface, and heat flows out through the whole inversion surface. This suggests that magnetic reconnection as predicted by Kadomtsev's model occurs in the first phase, but in the second phase, a different mechanism dominates heat flow. (author)

  11. Flow structure formation in an ion-unmagnetized plasma: The HYPER-II experiments

    Science.gov (United States)

    Terasaka, K.; Tanaka, M. Y.; Yoshimura, S.; Aramaki, M.; Sakamoto, Y.; Kawazu, F.; Furuta, K.; Takatsuka, N.; Masuda, M.; Nakano, R.

    2015-01-01

    The HYPER-II device has been constructed in Kyushu University to investigate the flow structure formation in an ion-unmagnetized plasma, which is an intermediate state of plasma and consists of unmagnetized ions and magnetized electrons. High density plasmas are produced by electron cyclotron resonance heating, and the flow field structure in an inhomogeneous magnetic field is investigated with a directional Langmuir probe method and a laser-induced fluorescence method. The experimental setup has been completed and the diagnostic systems have been installed to start the experiments. A set of coaxial electrodes will be introduced to control the azimuthal plasma rotation, and the effect of plasma rotation to generation of rectilinear flow structure will be studied. The HYPER-II experiments will clarify the overall flow structure in the inhomogeneous magnetic field and contribute to understanding characteristic feature of the intermediate state of plasma.

  12. On plasma flows along vortex lines

    International Nuclear Information System (INIS)

    Bagewadi, C.S.; Prasanna Kumar, K.N.

    1989-01-01

    The plasma flows are discussed and various intrinsic relations along the vortex lines and their principal normals and binormals are obtained. The effects of rotations on Bernoulli surfaces are also studied. (M.K.V.)

  13. Interferometric density measurements in the divertor and edge plasma regions for the additionally heated JT-60 plasmas

    International Nuclear Information System (INIS)

    Fukuda, T.; Yoshida, H.; Nagashima, A.; Ishida, S.; Kikuchi, M.; Yokomizo, H.

    1989-01-01

    The first divertor plasma density measurement and the interferometric edge plasma density measurement with boundary condition preserving millimeter waveguides were demonstrated to elucidate the mutual correlation among the divertor plasma, scrape-off layer plasma and the bulk plasma properties in the additionally heated JT-60 plasmas. The electron density in the divertor region exhibited a nonlinear dependence on the bulk plasma density for the joule-heated plasmas. When neutral beam heating is applied on the plasmas with the electron density above 2x10 19 /m 3 , however, the bulk plasma density is scraped off from the outer region to lead to density clamping, and the electron density in the divertor region rapidly increases over 1x10 20 /m 3 , from which we can deduce that the particle flow along the magnetic field is dominant, resulting in the apparent degradation of the particle confinement time. As for the case when neutral beam injection is applied to low-density plasmas, the bulk plasma electron density profile becomes flattened to yield a smaller density increase in the divertor region and no density clamping of the bulk plasma was observed. Simulation analysis which correlates the transport of the divertor plasma and the scrape-off layer plasma was also carried out to find the consistency with the experimental results. (orig.)

  14. Characteristics of an under-expanded supersonic flow in arcjet plasmas

    Science.gov (United States)

    Namba, Shinichi; Shikama, Taiichi; Sasano, Wataru; Tamura, Naoki; Endo, Takuma

    2018-06-01

    A compact apparatus to produce arcjet plasma was fabricated to investigate supersonic flow dynamics. Periodic bright–dark emission structures were formed in the arcjets, depending on the plasma source and ambient gas pressures in the vacuum chamber. A directional Langmuir probe (DLP) and emission spectroscopy were employed to characterize plasma parameters such as the Mach number of plasma flows and clarify the mechanism for the generation of the emission pattern. In particular, in order to investigate the influence of the Mach number on probe size, we used two DLPs of different probe size. The results indicated that the arcjets could be classified into shock-free expansion and under-expansion, and the behavior of plasma flow could be described by compressible fluid dynamics. Comparison of the Langmuir probe results with emission and laser absorption spectroscopy showed that the small diameter probe was reliable to determine the Mach number, even for the supersonic jet.

  15. Three Flow Features behind the Flow Control Authority of DBD Plasma Actuator: Result of High-Fidelity Simulations and the Related Experiments

    Directory of Open Access Journals (Sweden)

    Kozo Fujii

    2018-04-01

    Full Text Available Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an airfoil and the mechanism of flow control of this small device is discussed. The DBD plasma actuator, especially in burst mode, is shown to be very effective for controlling flow separation at Reynolds number of 6.3 × 104, when applied to the flows at an angle of attack higher than the stall. The analysis reveals that the flow structure includes three remarkable features that provide good authority for flow separation control with the appropriate actuator parameters. With proper setting of the actuator parameters to enhance the effective flow features for the application, good flow control can be achieved. Based on the analysis, guidelines for the effective use of DBD plasma actuators are proposed. A DBD plasma actuator is also applied to the flows under cruise conditions. With the DBD plasma actuator attached, a simple airfoil turns out to show higher lift-to-drag ratio than a well-designed airfoil.

  16. Observation of plasma hole in a rotating plasma

    International Nuclear Information System (INIS)

    Nagaoka, Kenichi; Ishihara, Tatsuzo; Okamoto, Atsushi; Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2001-01-01

    Plasma hole, a cylindrical density cavity, formed in a rotating plasma has been investigated experimentally. The plasma hole is characterized by large aspect ratio (length/radius ≥ 30), steep boundary layer between the hole and the ambient plasma (10 ion Larmor radius), and extremely high positive potential (130 V). The flow velocity field associated with plasma hole structure has been measured, and is found to have interesting features: (1) plasma rotates in azimuthal direction at a maximum velocity of order of ion sound speed, (2) plasma flows radially inward across the magnetic field line, (3) there present an axial flow reversal between core and peripheral region. It is found that the flow pattern of the plasma hole is very similar to the that of well-developed typhoon with core. (author)

  17. Measurement of plasma edge profile on Wendelstein 7-X

    Energy Technology Data Exchange (ETDEWEB)

    Drews, Philipp; Liang, Yunfeng; Neubauer, Olaf; Denner, Peter; Rack, Michael; Liu, Shaocheng; Wang, Nunchao; Nicolai, Dirk; Hollfeld, Klaus; Satheeswaran, Guruparan [Forschungszentrum Juelich, IEK4, Juelich (Germany); Grulke, Olaf [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Collaboration: W7-X Team

    2016-07-01

    Wendelstein 7-X (W7-X), currently under commissioning at the IPP Greifswald, will be the world's largest stellarator with modular superconducting coils, which will enable steady-state-like plasma operation of up to thirty minutes in order to explore the reactor relevance of this concept. The first operation phase of W7-X will employ a limiter configuration. It will be used primarily for setting up the diagnostics and testing the magnetic configuration. In conjunction with the multipurpose manipulator, a fast reciprocating probe is installed. The combined probe head will be used to measure the radial distribution of the magnetic field using magnetic pick-up coils; the plasma temperature and density profiles and the radial electric field using Langmuir pins; and the plasma flows using a Mach setup. As a quasi-isodynamic stellarator, it has been predicted that not only neoclassical but also turbulent transport will be comparable to or possibly even lower than that of tokamaks. Edge plasma profile measurements, especially those of the electron temperature and density, will play a key role in validating this performance in comparison to the tokamak and hence the viability of a stellarator fusion reactor. The edge plasma profile measurements using the combined probe head are presented.

  18. Finite toroidal flow generated by unstable tearing mode in a toroidal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hao, G. Z., E-mail: haogz@swip.ac.cn; Wang, A. K.; Xu, Y. H.; He, H. D.; Xu, M.; Qu, H. P.; Peng, X. D.; Xu, J. Q.; Qiu, X. M. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sun, Y. [Institute of Plasma Physics, Chinese Academic of Sciences, P.O. Box 1126, Hefei 230031 (China); Cui, S. Y. [School of Mathematics and Statistics Science, Ludong University, Yantai 264025 (China)

    2014-12-15

    The neoclassical toroidal plasma viscosity torque and electromagnetic torque, generated by tearing mode (TM) in a toroidal plasma, are numerically investigated using the MARS-Q code [Liu et al., Phys. Plasmas 20, 042503 (2013)]. It is found that an initially unstable tearing mode can intrinsically drive a toroidal plasma flow resulting in a steady state solution, in the absence of the external momentum input and external magnetic field perturbation. The saturated flow is in the order of 0.5%ω{sub A} at the q=2 rational surface in the considered case, with q and ω{sub A} being the safety factor and the Alfven frequency at the magnetic axis, respectively. The generation of the toroidal flow is robust, being insensitive to the given amplitude of the perturbation at initial state. On the other hand, the flow amplitude increases with increasing the plasma resistivity. Furthermore, the initially unstable tearing mode is fully stabilized by non-linear interaction with the self-generated toroidal flow.

  19. Study of Plasma Flow Modes in Imploding Nested Arrays

    Science.gov (United States)

    Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

    2018-02-01

    Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

  20. Quadrature interferometry for plasma density measurements

    International Nuclear Information System (INIS)

    Warthen, B.J.; Shlachter, J.S.

    1995-01-01

    A quadrature interferometer has been used routinely in several pulsed power experiments to measure the line-averaged electron density. The optical source is a 30 mW, continuous wave Nd-YAG laser operating at 1,300 nm. The light is coupled directly to an optical fiber and split into reference and scene beams with a fiber splitter. The scene beam is transported to and from the plasma using single mode optical fibers up to 100 m in length. To simplify alignment through the plasma, the authors have used GRIN lenses on both the launch and receive sides of the single pass transmission diagnostic where this is possible. The return beam passes through a half-wave plate which is used to compensate for polarization rotation associated with slow (hour) time scale drift in the single mode fibers. The reference beam is sent through a quarter-wave plate to produce circular polarization; mixing of the reference and scene beams is accomplished using a non-polarizing beam splitter, and the interference signals are focused into additional fibers which relay the light to fast photodiodes. The quadrature optics allow for an unambiguous determination of the slope of the density changes at inflection points. All of the beam processing optics are located on a stable optical table which is remote and protected from the experiment. Final setup of the interferometer is facilitated by looking at the Lissajous figure generated from the two quadrature components. The authors have used this interferometer to diagnose the background density in the Pegasus-II power flow channel, to study the plasma plume generated in foil implosion experiments, to measure the plasma blowoff during implosions, and to understand the plasma formation mechanism in a fusion target plasma system

  1. Kelvin-Helmholtz instability for a bounded plasma flow in a longitudinal magnetic field

    International Nuclear Information System (INIS)

    Burinskaya, T. M.; Shevelev, M. M.; Rauch, J.-L.

    2011-01-01

    Kelvin-Helmholtz MHD instability in a plane three-layer plasma is investigated. A general dispersion relation for the case of arbitrarily orientated magnetic fields and flow velocities in the layers is derived, and its solutions for a bounded plasma flow in a longitudinal magnetic field are studied numerically. Analysis of Kelvin-Helmholtz instability for different ion acoustic velocities shows that perturbations with wavelengths on the order of or longer than the flow thickness can grow in an arbitrary direction even at a zero temperature. Oscillations excited at small angles with respect to the magnetic field exist in a limited range of wavenumbers even without allowance for the finite width of the transition region between the flow and the ambient plasma. It is shown that, in a low-temperature plasma, solutions resulting in kink-like deformations of the plasma flow grow at a higher rate than those resulting in quasi-symmetric (sausage-like) deformations. The transverse structure of oscillatory-damped eigenmodes in a low-temperature plasma is analyzed. The results obtained are used to explain mechanisms for the excitation of ultra-low-frequency long-wavelength oscillations propagating along the magnetic field in the plasma sheet boundary layer of the Earth’s magnetotail penetrated by fast plasma flows.

  2. Gas flow dependence for plasma-needle disinfection of S. mutans bacteria

    International Nuclear Information System (INIS)

    Goree, J; Liu Bin; Drake, David

    2006-01-01

    The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence

  3. Gas flow dependence for plasma-needle disinfection of S. mutans bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Goree, J [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Liu Bin [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Drake, David [Dows Institute for Dental Research, Dept. of Endodontics, College of Dentistry, University of Iowa, Iowa City, IA 52242 (United States)

    2006-08-21

    The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence.

  4. Plasma sheet fast flows and auroral dynamics during substorm: a case study

    Directory of Open Access Journals (Sweden)

    N. L. Borodkova

    2002-03-01

    Full Text Available Interball-1 observations of a substorm development in the mid-tail on 16 December 1998 are compared with the auroral dynamics obtained from the Polar UV imager. Using these data, the relationship between plasma flow directions in the tail and the location of the auroral activation is examined. Main attention is given to tailward and earth-ward plasma flows, interpreted as signatures of a Near Earth Neutral Line (NENL. It is unambiguously shown that in the mid-plasma sheet the flows were directed tailward when the auroral bulge developed equatorward of the spacecraft ionospheric footprint. On the contrary, when active auroras moved poleward of the Interball-1 projection, earthward fast flow bursts were observed. This confirms the concept that the NENL (or flow reversal region is the source of auroras forming the poleward edge of the auroral bulge. The observed earthward flow bursts have all typical signatures of Bursty Bulk Flows (BBFs, described by Angelopolous et al. (1992. These BBFs are related to substorm activations starting at the poleward edge of the expanded auroral bulge. We interpret the BBFs as a result of reconnection pulses occurring tail-ward of Interball-1. In addition, some non-typically observed phenomena were detected in the plasma sheet during this substorm: (i tailward/earthward flows were superimposed on a very strong duskward flow, and (ii wavy structures of both magnetic field and plasma density were registered. The latter observation is probably linked to the filamentary structure of the current sheet.Key words. Magnetospheric physics (auroral phenomena; plasma sheet; storms and substorms

  5. Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

    International Nuclear Information System (INIS)

    Ida, Katsumi

    2001-01-01

    The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)

  6. Measurements and simulations of scrape-off layer flows in the DIII-D Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Groth, M. [Lawrence Livermore National Laboratory, General Atomics, P.O. Box 85608, Livermore, San Diego, CA 92186-5608 (United States); General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States)], E-mail: groth@fusion.gat.com; Porter, G.D. [Lawrence Livermore National Laboratory, General Atomics, P.O. Box 85608, Livermore, San Diego, CA 92186-5608 (United States); Boedo, J.A. [University of California San Diego, La Jolla, CA 92093 (United States); Brooks, N.H. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Isler, R.C. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); West, W.P.; Bray, B.D. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Fenstermacher, M.E. [Lawrence Livermore National Laboratory, General Atomics, P.O. Box 85608, Livermore, San Diego, CA 92186-5608 (United States); Groebner, R.J.; Leonard, A.W. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Moyer, R.A. [University of California San Diego, La Jolla, CA 92093 (United States); Rognlien, T.D. [Lawrence Livermore National Laboratory, General Atomics, P.O. Box 85608, Livermore, San Diego, CA 92186-5608 (United States); Watkins, J.G. [Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185 (United States); Yu, J.H. [University of California San Diego, La Jolla, CA 92093 (United States)

    2009-06-15

    Flow velocities of the order 10-20 km/s in the direction of the high-field side divertor have been measured for deuterons and low charge-state carbon ions in the scrape-off layer at the crown of low-density L-mode plasmas, suggesting that these carbon ions at the crown move with the background plasma flow. Simulations with the multi-fluid edge code UEDGE including cross-field drifts due to E x B and B x {nabla}B yield calculated divertor conditions which are more consistent with the measurements, but flows at the crown that are stagnant or in the opposite direction than observed. The simulations indicate that both the ion temperature gradient force and deuteron frictional drag play a role in determining the flow direction and magnitude of low charge-state carbon ions. The effect of the assumed radial transport model, toroidal core rotation, and neutral pumping at the divertor plates on the flow at the crown is investigated.

  7. Excitation of nonlinear wave patterns in flowing complex plasmas

    Science.gov (United States)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2018-01-01

    We describe experimental observations of nonlinear wave structures excited by a supersonic mass flow of dust particles over an electrostatic potential hill in a dusty plasma medium. The experiments have been carried out in a Π- shaped experimental (DPEx) device in which micron sized Kaolin particles are embedded in a DC glow discharge Argon plasma. An equilibrium dust cloud is formed by maintaining the pumping speed and gas flow rate and the dust flow is induced either by suddenly reducing the height of a potential hill or by suddenly reducing the gas flow rate. For a supersonic flow of the dust fluid precursor solitons are seen to propagate in the upstream direction while wake structures propagate in the downstream direction. For flow speeds with a Mach number greater than 2 the dust particles flowing over the potential hill give rise to dispersive dust acoustic shock waves. The experimental results compare favorably with model theories based on forced K-dV and K-dV Burger's equations.

  8. Comparison of Theory with Rotation Measurements in JET ICRH Plasmas

    International Nuclear Information System (INIS)

    R.V. Budny; C.S. Chang; C. Giroud; R.J. Goldston; D. McCune; J. Ongena; F.W. Perkins; R.B. White; K.-D. Zastrow; and contributors to the EFDA-JET work programme

    2001-01-01

    Plasma rotation appears to improve plasma performance by increasing the E x B flow shearing rate, thus decreasing radial correlations in the microturbulence. Also, plasma rotation can increase the stability to resistive MHD modes. In the Joint European Torus (JET), toroidal rotation rates omega (subscript ''tor'') with high Mach numbers are generally measured in NBI-heated plasmas (since the neutral beams aim in the co-plasma current direction). They are considerably lower with only ICRH (and Ohmic) heating, but still surprisingly large considering that ICRH appears to inject relatively small amounts of angular momentum. Either the applied torques are larger than naively expected, or the anomalous transport of angular momentum is smaller than expected. Since ICRH is one of the main candidates for heating next-step tokamaks, and for creating burning plasmas in future tokamak reactors, this paper attempts to understand ICRH-induced plasma rotation

  9. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  10. The interaction of a flowing plasma with a dipole magnetic field: measurements and modelling of a diamagnetic cavity relevant to spacecraft protection

    International Nuclear Information System (INIS)

    Bamford, R; Bradford, J; Bingham, R; Gargate, L; Hapgood, M; Stamper, R; Gibson, K J; Thornton, A J; Silva, L O; Fonseca, R A; Norberg, C; Todd, T

    2008-01-01

    Here we describe a new experiment to test the shielding concept of a dipole-like magnetic field and plasma, surrounding a spacecraft forming a 'mini magnetosphere'. Initial laboratory experiments have been conducted to determine the effectiveness of a magnetized plasma barrier to be able to expel an impacting, low beta, supersonic flowing energetic plasma representing the solar wind. Optical and Langmuir probe data of the plasma density, the plasma flow velocity and the intensity of the dipole field clearly show the creation of a narrow transport barrier region and diamagnetic cavity virtually devoid of energetic plasma particles. This demonstrates the potential viability of being able to create a small 'hole' in a solar wind plasma, of the order of the ion Larmor orbit width, in which an inhabited spacecraft could reside in relative safety. The experimental results have been quantitatively compared with a 3D particle-in-cell 'hybrid' code simulation that uses kinetic ions and fluid electrons, showing good qualitative agreement and excellent quantitative agreement. Together the results demonstrate the pivotal role of particle kinetics in determining generic plasma transport barriers.

  11. Development of supersonic plasma flows by use of a magnetic nozzle and an ICRF heating

    Energy Technology Data Exchange (ETDEWEB)

    Inutake, M.; Ando, A.; Hattori, K.; Tobari, H.; Hosokawa, Y.; Sato, R.; Hatanaka, M.; Harata, K. [Tohoku Univ., Dept. of Electrical Engineering, Sendai (Japan)

    2004-07-01

    A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in space and fusion plasmas. There are a few experimental researches on production and control of a fast flowing plasma in spite of a growing significance in the magnetized-plasma flow dynamics. A magneto-plasma-dynamic arc-jet (MPDA) is one of promising devices to produce a supersonic plasma flow and has been utilized as an electric propulsion device with a higher specific impulse and a relatively larger thrust. We have improved the performance of an MPDA to produce a quasi-steady plasma flow with a transonic and supersonic Mach number in a highly-ionized state. There are two methods in order to control an ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to use a magnetic Laval nozzle to convert a thermal energy to a flow energy and the other is a combined system of an ion heating and a divergent magnetic nozzle. The former is an analogous method to a compressible air flow and the latter is the method proposed in an advanced thruster for a manned interplanetary space mission. We have clarified the plasma flow characteristics in various shapes of a magnetic field configuration. It was demonstrated that the Mach number of the plasma flow could increase up to almost 3 in a divergent magnetic nozzle field. This paper reports recent results on the flow field improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency) heating of a supersonic plasma by use of a helical antenna. (authors)

  12. Investigating the flow dynamics and chemistry of an expanding thermal plasma through CH(A-X) emission spectra

    NARCIS (Netherlands)

    Hansen, T. A. R.; Colsters, P. G. J.; M. C. M. van de Sanden,; Engeln, R.

    2011-01-01

    The gas flow in a linear plasma reactor and the plasma chemistry during hydrogenated amorphous carbon and graphite etching are investigated via time and spatially resolved measurements of the ion density and CH emission. A convolution of the ion and hydrocarbon density shows the importance of charge

  13. Improvement of Flow Characteristics for an Advanced Plasma Thruster

    International Nuclear Information System (INIS)

    Inutake, M.; Hosokawa, Y.; Sato, R.; Ando, A.; Tobari, H.; Hattori, K.

    2005-01-01

    A higher specific impulse and a larger thrust are required for a manned interplanetary space thruster. Until the realization of a fusion-plasma thruster, a magneto-plasma-dynamic arcjet (MPDA) powered by a fission reactor is one of the promising candidates for a manned Mars space thruster. The MPDA plasma is accelerated axially by a self-induced j x B force. Thrust performance of the MPDA is expected to increase by applying a magnetic nozzle instead of a solid nozzle. In order to get a much higher thruster performance, two methods have been investigated in the HITOP device, Tohoku University. One is to use a magnetic Laval nozzle in the vicinity of the MPDA muzzle for converting the high ion thermal energy to the axial flow energy. The other is to heat ions by use of an ICRF antenna in the divergent magnetic nozzle. It is found that by use of a small-sized Laval-type magnetic nozzle, the subsonic flow near the muzzle is converted to be supersonic through the magnetic Laval nozzle. A fast-flowing plasma is successfully heated by use of an ICRF antenna in the magnetic beach configuration

  14. Investigation on Plasma Jet Flow Phenomena During DC Air Arc Motion in Bridge-Type Contacts

    Science.gov (United States)

    Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei

    2016-05-01

    Arc plasma jet flow in the air was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet flow appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet flow. Then, to make the nature of arc plasma jet flow phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc flow velocity field showed that the circular vortex was an embodiment of the arc plasma jet flow progress. The combined action of volume force and contact surface was the main reason of the arc jet flow. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)

  15. Observations of plasma vortices in the vicinity of flow-braking: a case study

    Directory of Open Access Journals (Sweden)

    K. Keika

    2009-08-01

    Full Text Available We examine fast plasma flows and magnetic field fluctuations observed by THEMIS at 03:00–03:30 UT on 12 December 2007. All THEMIS probes are situated in the near-Earth plasma sheet (XSM>−10 RE with 1–2 RE spacecraft separations in azimuthal and radial directions. We focus on the observations of plasma convective flows made simultaneously by more than one THEMIS probe. At about 03:10 UT and 03:14 UT, the THEMIS P2 probe observed earthward flows of >100 km/s. The THEMIS P1 probe, located duskward and earthward of P2, observed tailward flows under a positive Bz. The inner most probe THEMIS P4, located at almost the same MLT as THEMIS P1 and P2, did not see any clear flow. We examine the convective flow patterns for the THEMIS observations. We conclude that plasma vortices are formed near the region where the earthward flows slow down and turn in azimuthal directions.

  16. Directed flow in heavy-ion collisions at NICA: What is interesting to measure?

    Energy Technology Data Exchange (ETDEWEB)

    Bravina, L.V. [University of Oslo, Department of Physics, Oslo (Norway); National Research Nuclear University ' ' MEPhI' ' , (Moscow Engineering Physics Institute), Moscow (Russian Federation); Goethe University, Frankfurt Institute for Advanced Studies (FIAS), Frankfurt (Germany); Zabrodin, E.E. [University of Oslo, Department of Physics, Oslo (Norway); Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' , (Moscow Engineering Physics Institute), Moscow (Russian Federation); Goethe University, Frankfurt Institute for Advanced Studies (FIAS), Frankfurt (Germany)

    2016-08-15

    We study the formation of the directed flow of hadrons in nuclear collisions at energies between AGS and SPS in Monte Carlo cascade model. The slope of the proton flow at midrapidity tends to zero (softening) with increasing impact parameter of the collision. For very peripheral topologies this slope becomes negative (antiflow). The effect is caused by rescattering of hadrons in remnants of the colliding nuclei. Since the softening of the proton flow can be misinterpreted as indication of the presence of quark-gluon plasma, we propose several measurements at NICA facility which can help one to distinguish between the cases with and without the plasma formation. (orig.)

  17. Characteristics of a plasma flow field produced by a metal array bridge foil explosion

    Science.gov (United States)

    Junying, WU; Long, WANG; Yase, LI; Lijun, YANG; Manzoor, SULTAN; Lang, CHEN

    2018-07-01

    To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha–Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet’s center region sharply increase because of the superposition of plasma beams.

  18. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    Science.gov (United States)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  19. Analysis of IBW-driven plasma flows in tokamaks

    International Nuclear Information System (INIS)

    Berry, L.A.; Jaeger, E.F.; D'Azevedo, E.F.; Batchelor, D.B.; Carlsson, J.A.; Carter, M.D.; Cesario, R.

    2001-01-01

    Both theory and experiment have suggested that damping of Ion Bernstein Waves (IBWs) at ion cyclotron frequency harmonics could drive poloidal flows and lead to enhanced confinement for tokamaks. However, the early analyses were based on Reynolds stress closures of moment equations. More rigorous, finite Larmor radius (FLR) expansions of the radio frequency (RF) kinetic pressure for low harmonic interactions indicated that the Reynolds stress approximation was not generally valid, and resulted in significant changes in the plasma flow response. These changes were largest for wave interactions driven by finite Larmour radius effects. To provide a better assessment of higher harmonic interactions and IBW flow drive prospects, the electromagnetic (E and M) and RF kinetic force models are extended with no assumptions regarding the smallness of the ion Larmor radius. For both models, a spectral-width approximation was used to make the numerical analysis tractable. In addition, it was necessary to include the effects of plasma equilibrium gradients on the plasma conductivity and the RF-induced momentum in order to conserve energy and momentum. The analysis of high-harmonic IBW interactions for TFTR and FTU parameters indicates significant poloidal flow shears (relative to turbulence correlation times) for power levels available in present experiments. Recent advances in all-orders calculations of E and M fields in 2-D are also discussed. (author)

  20. Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment

    International Nuclear Information System (INIS)

    Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

    2012-01-01

    This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H α and the H β lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

  1. On the geometry of field lines in plasma flows

    International Nuclear Information System (INIS)

    Bagewadi, C.S.; Prasanna Kumar, K.N.

    1988-01-01

    Many research investigators have applied differential geometry to plasma. Intrinsic properties of fluid flows in streamline, vortex line geometries are we ll known under certain set of geometric conditions. Though this approach has yielded some interesting results but the most general properties of flows can be obtained, using eight geometric parameters ksub(s), tsub(s) θsub(ns), θsub(bs), phisub(s), Ωsub(s), div n, div b and the basic necessary conditions to be satisfied by the flow in general anholonomic co-ordinate system together with the conditions to be satisfied by the geometric parameters of triply orthogonal spatial curves of congruences. Adopting the above techniques for triply orthogonal spatial curves of congruences related to the lines of forces, Purushottam has studied the geometric properties of spatial hydromagnetic fluid flows. Again these results have been studied by him in general along the field lines. These results have been studied for plasma along field lines and the basic equations of plasma have been expressed in intrinsic decomposition forms. Furthe r complex lamellar magnetic field have been studied by introducing Lie surface. (a uthor)

  2. Measurements and Simulations of Scrape-off Layer Flows in the DIII-D Tokamak

    International Nuclear Information System (INIS)

    Groth, M.; Porter, G.D.; Boedo, J.A.; Brooks, N.H.; Isler, Ralph C.; West, W.P.; Bray, B.D.; Fenstermacher, M.E.; Groebner, R.J.; Leonard, A.W.; Moyer, R.A.; Rognlien, T.D.; Watkins, J.G.; Yu, J.H.

    2009-01-01

    Flow velocities of the order 10-20 km/s in the direction of the high-field side divertor have been measured for deuterons and low charge-state carbon ions in the scrape-off layer at the crown of low-density L-mode plasmas, suggesting that these carbon ions at the crown move with the background plasma flow. Simulations with the multi-fluid edge code UEDGE including cross-field drifts due to E x B and B x del B yield calculated divertor conditions which are more consistent with the measurements, but flows at the crown that are stagnant or in the opposite direction than observed. The simulations indicate that both the ion temperature gradient force and deuteron frictional drag play a role in determining the flow direction and magnitude of low charge-state carbon ions. The effect of the assumed radial transport model, toroidal core rotation, and neutral pumping at the divertor plates on the flow at the crown is investigated. (C) 2009 Elsevier B.V. All rights reserved.

  3. Transport barriers with and without shear flows in a magnetized plasma

    International Nuclear Information System (INIS)

    Martinell, Julio J.

    2014-01-01

    Different ways of producing a transport barrier in a toroidal magnetized plasma are discussed and the properties of the barriers are analyzed. The first mechanism is associated with the presence of a sheared plasma flow that is present in a limited region of the plasma, which creates a zonal flow. In contrast to the usual paradigm stating that the sheared flow reduces the turbulence correlation length and leads to suppression of the fluctuation driven transport in the region of highest shear, it is shown that from the perspective of chaotic transport of plasma particles in the fluctuation fields, the transport barrier is formed in the region of zero shear and it can be destroyed when the fluctuation level is high enough. It is also shown that finite gyroradius effects modify the dynamics and introduces new conditions for barrier formation. The second mechanism considers a method in which radio-frequency waves injected into the plasma can stabilize the drift waves and therefore the anomalous transport is reduced, creating a barrier. This process does not involve the presence of sheared flows and depends only on the effect of the RF wave field on the drift waves. The stabilizing effect in this case is due to the nonlinear ponderomotive force which acts in a way that offsets the pressure gradient destabilization. Finally, a mechanism based on the ponderomotive force of RF waves is described which produces poloidal plasma rotation around the resonant surface due to the asymmetry of induced transport; it creates a transport barrier by shear flow stabilization of turbulence

  4. 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.

  5. The measurement of single particle temperature in plasma sprays

    International Nuclear Information System (INIS)

    Fincke, J.R.; Swank, W.D.; Bolsaitis, P.P.; Elliott, J.F.

    1990-01-01

    A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs

  6. Radially sheared azimuthal flows and turbulent transport in a cylindrical helicon plasma device

    International Nuclear Information System (INIS)

    Tynan, G R; Burin, M J; Holland, C; Antar, G; Diamond, P H

    2004-01-01

    A radially sheared azimuthal flow is observed in a cylindrical helicon plasma device. The shear flow is roughly azimuthally symmetric and contains both time-stationary and slowly varying components. The turbulent radial particle flux is found to peak near the density gradient maximum and vanishes at the shear layer location. The shape of the radial plasma potential profile associated with the azimuthal E x B flow is predicted accurately by theory. The existence of the mean shear flow in a plasma with finite flow damping from ion-neutral collisions and no external momentum input implies the existence of radial angular momentum transport from the turbulent Reynolds-stress

  7. Magnetorotational and Parker instabilities in magnetized plasma Dean flow as applied to centrifugally confined plasmas

    International Nuclear Information System (INIS)

    Huang Yimin; Hassam, A.B.

    2003-01-01

    The ideal magnetohydrodynamics stability of a Dean flow plasma supported against centrifugal forces by an axial magnetic field is studied. Only axisymmetric perturbations are allowed for simplicity. Two distinct but coupled destabilization mechanisms are present: flow shear (magnetorotational instability) and magnetic buoyancy (Parker instability). It is shown that the flow shear alone is likely insufficient to destabilize the plasma, but the magnetic buoyancy instability could occur. For a high Mach number (M S ), high Alfven Mach number (M A ) system with M S M A > or approx. πR/a (R/a is the aspect ratio), the Parker instability is unstable for long axial wavelength modes. Implications for the centrifugal confinement approach to magnetic fusion are also discussed

  8. Dynamics and control of the vortex flow behind a slender conical forebody by a pair of plasma actuators

    Science.gov (United States)

    Meng, Xuanshi; Long, Yuexiao; Wang, Jianlei; Liu, Feng; Luo, Shijun

    2018-02-01

    Detailed particle-image-velocimetry (PIV) and surface pressure measurements are presented to study the vortex flow behind a slender conical forebody at high angles of attack. The results confirm the existence of two randomly appearing mirror imaged asymmetric bi-stable states of the separation vortices, giving rise to large side force and moment. A pair of carefully designed dielectric barrier discharge plasma actuators mounted near the apex and on both sides of the conical body are used to manipulate the vortex flow and thus provide control of the side forces on the body without using flaps. By making use of a duty-cycle actuation scheme that alternately actuates the port and starboard plasma actuators and optimizing the duty-cycle frequency, the present work demonstrates the feasibility of achieving a nearly perfect linear proportional control of the side force and moment in response to the duty-cycle ratio. Phase-locked PIV and surface pressure measurements are used to study the unsteady dynamic evolution of the flow within one duty-cycle actuation to reveal the flow control mechanism. It is found that under the duty-cycle actuation with the optimized frequency, the vortex flow essentially follows the plasma actuation by alternating between the two bi-stable states controlled directly by the duty-cycle ratio.

  9. Change of Zonal Flow Spectra in the JIPP T-IIU Tokamak Plasmas

    International Nuclear Information System (INIS)

    Hamada, Y.; Watari, T.; Yamagishi, O.; Nishizawa, A.; Narihara, K.; Kawasumi, Y.; Ido, T.; Kojima, M.; Toi, K.

    2007-01-01

    When Ohmically heated low-density plasmas are additionally heated by higher-harmonics ion-cyclotron-range-of frequency heating, heated by neutral beam injection, or strongly gas puffed, the intensity of zonal flows in the geodesic acoustic mode frequency range in the tokamak core plasma decreases sharply and that of low-frequency zonal flow grows drastically. This is accompanied by a damping of the drift wave propagating in the electron diamagnetic drift direction, turbulence by trapped electron mode (TEM), and the increase of the mode propagating to ion diamagnetic drift direction (ITG). In the half-radius region, TEM and high-frequency zonal flows remain intense in both OH and heated phases. ITG and low-frequency zonal flows grow in heated plasmas, suggesting a strong coupling between ITG and low-frequency zonal flow

  10. Metal droplet erosion and shielding plasma layer under plasma flows typical of transient processes in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Martynenko, Yu. V., E-mail: Martynenko-YV@nrcki.ru [National Research Nuclear University “MEPhI” (Russian Federation)

    2017-03-15

    It is shown that the shielding plasma layer and metal droplet erosion in tokamaks are closely interrelated, because shielding plasma forms from the evaporated metal droplets, while droplet erosion is caused by the shielding plasma flow over the melted metal surface. Analysis of experimental data and theoretical models of these processes is presented.

  11. Characterization of the supersonic flowing microwave discharge using two dimensional plasma tomography

    Energy Technology Data Exchange (ETDEWEB)

    Nikolic, M.; Samolov, A.; Popovic, S.; Vuskovic, L.; Godunov, A. [Department of Physics, Center for Accelerator Science, Old Dominion University, Norfolk, Virginia 23529 (United States); Cuckov, F. [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2013-03-14

    A tomographic numerical method based on the two-dimensional Radon formula for a cylindrical cavity has been employed for obtaining spatial distributions of the argon excited levels. The spectroscopy measurements were taken at different positions and directions to observe populations of excited species in the plasmoid region and the corresponding excitation temperatures. Excited argon states are concentrated near the tube walls, thus, confirming the assumption that the post discharge plasma is dominantly sustained by travelling surface wave. An automated optical measurement system has been developed for reconstruction of local plasma parameters of the plasmoid structure formed in an argon supersonic flowing microwave discharge. The system carries out angle and distance measurements using a rotating, flat mirror, as well as two high precision stepper motors operated by a microcontroller-based system and several sensors for precise feedback control.

  12. Three-dimensional rotational plasma flows near solid surfaces in an axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Gorshunov, N. M., E-mail: gorshunov-nm@nrcki.ru; Potanin, E. P., E-mail: potanin45@yandex.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    A rotational flow of a conducting viscous medium near an extended dielectric disk in a uniform axial magnetic field is analyzed in the magnetohydrodynamic (MHD) approach. An analytical solution to the system of nonlinear differential MHD equations of motion in the boundary layer for the general case of different rotation velocities of the disk and medium is obtained using a modified Slezkin–Targ method. A particular case of a medium rotating near a stationary disk imitating the end surface of a laboratory device is considered. The characteristics of a hydrodynamic flow near the disk surface are calculated within the model of a finite-thickness boundary layer. The influence of the magnetic field on the intensity of the secondary flow is studied. Calculations are performed for a weakly ionized dense plasma flow without allowance for the Hall effect and plasma compressibility. An MHD flow in a rotating cylinder bounded from above by a retarding cap is considered. The results obtained can be used to estimate the influence of the end surfaces on the main azimuthal flow, as well as the intensities of circulating flows in various devices with rotating plasmas, in particular, in plasma centrifuges and laboratory devices designed to study instabilities of rotating plasmas.

  13. Measurement of plasma flows into tile gaps

    Czech Academy of Sciences Publication Activity Database

    Dejarnac, Renaud; Komm, Michael; Stöckel, Jan; Pánek, Radomír

    2008-01-01

    Roč. 382, č. 1 (2008), s. 31-34 ISSN 0022-3115 R&D Projects: GA AV ČR KJB100430602 Institutional research plan: CEZ:AV0Z20430508 Keywords : Tokamak diagnostic * Gaps * Ion saturation current * Edge modeling * Sheaths Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.501, year: 2008

  14. Comparison of measurement of 99mTc-MAG3 plasma clearance by single plasma sample and renal uptake ratio

    International Nuclear Information System (INIS)

    Ushijima, Yo; Sugihara, Hiroki; Okuyama, Chio; Okitsu, Sigeyuki; Nii, Takeshi; Nishida, Takuji; Okamoto, Kunio; Maeda, Tomoho

    1997-01-01

    Measurement of 99m Tc-MAG 3 plasma clearance based on one-compartment model (MPC method) is a non-invasive method using the renal uptake ratio. We evaluated the clinical usefulness of this method, compared with effective renal plasma flow (ERPF) using 123 I-OIH and two single-plasma sample methods using 99m Tc-MAG 3 (Russell method and Bubeck method). The ratio of 99m Tc-MAG 3 clearance to ERPF was 1.00±0.26. MPC method correlated well with Russell and Bubeck methods (r=0.904, r=0.897). We conclude that MPC method is a suitable replacement for single-plasma sample method in routine clinical use. (author)

  15. Using Crossflow for Flow Measurements and Flow Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, A.; Chudnovsky, L.; Lopeza, A. [Advanced Measurement and Analysis Group Inc., Ontario (Canada); Park, M. H. [Sungjin Nuclear Engineering Co., Ltd., Gyeongju (Korea, Republic of)

    2016-10-15

    Ultrasonic Cross Correlation Flow Measurements are based on a flow measurement method that is based on measuring the transport time of turbulent structures. The cross correlation flow meter CROSSFLOW is designed and manufactured by Advanced Measurement and Analysis Group Inc. (AMAG), and is used around the world for various flow measurements. Particularly, CROSSFLOW has been used for boiler feedwater flow measurements, including Measurement Uncertainty Recovery (MUR) reactor power uprate in 14 nuclear reactors in the United States and in Europe. More than 100 CROSSFLOW transducers are currently installed in CANDU reactors around the world, including Wolsung NPP in Korea, for flow verification in ShutDown System (SDS) channels. Other CROSSFLOW applications include reactor coolant gross flow measurements, reactor channel flow measurements in all channels in CANDU reactors, boiler blowdown flow measurement, and service water flow measurement. Cross correlation flow measurement is a robust ultrasonic flow measurement tool used in nuclear power plants around the world for various applications. Mathematical modeling of the CROSSFLOW agrees well with laboratory test results and can be used as a tool in determining the effect of flow conditions on CROSSFLOW output and on designing and optimizing laboratory testing, in order to ensure traceability of field flow measurements to laboratory testing within desirable uncertainty.

  16. Measurements and Simulations of Surface Dielectric Barrier Discharges Used as Plasma Actuators

    Science.gov (United States)

    Hoskinson, Alan R.

    2012-01-01

    This report is a Ph.D. dissertation performed under NRA cooperative agreement and submitted as part of the final report. Asymmetric surface dielectric barrier discharges (DBDs) have shown promise for use as aerodynamic actuators for active flow control. In this project we studied DBD actuators experimentally and numerically. Our DBDs used a symmetric triangular high voltage waveform to generate plasma in atmospheric pressure air. Time-averaged measurements indicated that the induced force of a single barrier actuator design (one electrode insulated from the plasma) can be increased exponentially above the results of previous studies by decreasing both the length and thickness of the electrode exposed to the plasma. This increased force may allow these devices to control flow separation in a wider range of flow environments. Experiments using an intensified digital camera to examine the plasma on time scales of a few nanoseconds showed that, in addition to the previously-observed filamentary and jet-like plasma structures, discharges with very thin exposed electrodes exhibited a weak but constant plasma immediately adjacent to those electrodes. In double-barrier actuators (both electrodes insulated), decreasing the diameter of the narrower electrode lead to increasing forces, and recorded images showed the simultaneous existence of both filamentary and jet-like plasma structures. The development and application of a time-dependent, two-dimensional computational fluid plasma model has aided in understanding the detailed physics of surface DBDs at all-time scales. For simulated single-barrier discharges, the model qualitatively reproduced the filamentary and jet-like micro-discharge structures. The model was somewhat successful in reproducing the observed characteristics of double-barrier actuators. For both actuator geometries, the model indicated that the majority of the forces induced on the neutral gas occur in between micro-discharges as the plasmas decay.

  17. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    International Nuclear Information System (INIS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-01-01

    Graphical abstract: - Highlights: • Controlling hydrophilicity of polymer film by varying gas flow rate is proposed in atmospheric-pressure homogeneous plasma treatment. • Without employing additional reactive gas, requiring more plasma power and longer treatment time, hydrophilicity of polyimide films was improved after the low-gas-flow plasma treatment. • The gas flow rate affects the hydrophilic properties of polymer surface by changing the discharge atmosphere in the particular geometry of the reactor developed. • Low-gas-flow induced wettability control suggests effective and economical plasma treatment. - Abstract: This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films

  18. MHD equilibrium of toroidal fusion plasma with stationary flows

    International Nuclear Information System (INIS)

    Galkowski, A.

    1994-01-01

    Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad's ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs

  19. Turbulence spectra, transport, and E × B flows in helical plasmas

    International Nuclear Information System (INIS)

    Watanabe, T.-H.; Nunami, M.; Sugama, H.; Satake, S.; Matsuoka, S.; Ishizawa, A.; Tanaka, K.; Maeyama, Shinya

    2012-11-01

    Gyrokinetic simulation of ion temperature gradient turbulence and zonal flows for helical plasmas has been validated against the Large Helical Device experiments with high ion temperature, where a reduced modeling of ion heat transport is also considered. It is confirmed by the entropy transfer analysis that the turbulence spectrum elongated in the radial wavenumber space is associated with successive interactions with zonal flows. A novel multi-scale simulation for turbulence and zonal flows in poloidally-rotating helical plasmas has demonstrated strong zonal flow generation by turbulence, which implies that turbulent transport processes in non-axisymmetric systems are coupled to neoclassical transport through the macroscopic E × B flows determined by the ambipolarty condition for neoclassical particle fluxes. (author)

  20. QUICK-FIRE: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

    1985-01-01

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion

  1. Time and space-correlated plasma potential measurements in the near field of a coaxial Hall plasma discharge

    International Nuclear Information System (INIS)

    Smith, A. W.; Cappelli, M. A.

    2009-01-01

    Space- and time-correlated measurements of floating and plasma potential are made in the near field, external flow cathode region of a coaxial Hall plasma discharge using an emissive probe synchronized to quasicoherent fluctuations in discharge current. The luminous axial feature frequently observed in the near field of operating plasma accelerators is found to be concomitant with a spike in the plasma potential (and electron temperature). The structure of the plasma potential allows for multiple avenues for back-streaming ions to accelerate toward the discharge front pole and may pull some classes of ions toward the central axis. The fluctuations in plasma properties exhibit a complex structure at frequencies on the order of the so-called 'breathing mode' ionization instability often seen in these types of discharges. Most notably, the plasma potential appears to fluctuate in a helical fashion, resembling tilted drift waves rotating about the central axis. A simple analysis of these waves draws attention to the possible role that they may play in driving anomalous cross-field electron transport in the near field region.

  2. Increased kidney size, glomerular filtration rate and renal plasma flow in short-term insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Christiansen, JS; Gammelgaard, J; Frandsen, M

    1981-01-01

    Glomerular filtration rate (GFR), renal plasma flow (RPF) and kidney volume were measured in thirteen male subjects (mean age 30 years) with short-term insulin-dependent diabetes (mean duration of disease 2.4 years) and fourteen normal male subjects (mean age 29 years). GFR and RPF were measured...

  3. High Mach flow associated with plasma detachment in JT-60U

    International Nuclear Information System (INIS)

    Hatayama, A.; Hoshino, K.; Miyamoto, K.

    2003-01-01

    Recent new results of the high Mach flows associated with plasma detachment are presented on the basis of numerical simulations by a 2-D edge simulation code (the B2-Eirene code) and their comparisons with experiments in JT-60U W-shaped divertor plasma. High Mach flows appear near the ionization front away from the target plate. The plasma static pressure rapidly drops, while the total pressure is kept almost constant near the ionization front, because the ionization front near the X-point is clearly separated from the momentum loss region near the target plate. Redistribution from static to dynamic pressure without a large momentum loss is confirmed to be a possible mechanism of the high Mach flows. It has been also shown that the radial structure of the high Mach flow near the X point away from the target plate has a strong correlation with the DOD (Degree of Detachment) at the target plate. Also, we have made systematic analyses on the high Mach flows for both the 'Open' geometry and the 'W-shaped' geometry of JT-60U in order to clarify the geometric effects on the flows. (author)

  4. Asymmetrical flow field-flow fractionation coupled with multiple detections: A complementary approach in the characterization of egg yolk plasma.

    Science.gov (United States)

    Dou, Haiyang; Li, Yueqiu; Choi, Jaeyeong; Huo, Shuying; Ding, Liang; Shen, Shigang; Lee, Seungho

    2016-09-23

    The capability of asymmetrical flow field-flow fractionation (AF4) coupled with UV/VIS, multiangle light scattering (MALS) and quasi-elastic light scattering (QELS) (AF4-UV-MALS-QELS) for separation and characterization of egg yolk plasma was evaluated. The accuracy of hydrodynamic radius (Rh) obtained from QELS and AF4 theory (using both simplified and full expression of AF4 retention equations) was discussed. The conformation of low density lipoprotein (LDL) and its aggregates in egg yolk plasma was discussed based on the ratio of radius of gyration (Rg) to Rh together with the results from bio-transmission electron microscopy (Bio-TEM). The results indicate that the full retention equation is more relevant than simplified version for the Rh determination at high cross flow rate. The Rh from online QELS is reliable only at a specific range of sample concentration. The effect of programmed cross flow rate (linear and exponential decay) on the analysis of egg yolk plasma was also investigated. It was found that the use of an exponentially decaying cross flow rate not only reduces the AF4 analysis time of the egg yolk plasma, but also provides better resolution than the use of either a constant or linearly decaying cross flow rate. A combination of an exponentially decaying cross flow AF4-UV-MALS-QELS and the utilization of full retention equation was proved to be a useful method for the separation and characterization of egg yolk plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Science.gov (United States)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  6. Plasma potential formation and measurement in TMX-U and MFTF-B

    International Nuclear Information System (INIS)

    Grubb, D.P.

    1984-01-01

    Tandem mirrors control the axial variation of the plasma potential to create electrostatic plugs that improve the axial confinement of central cell ions and, in a thermal barrier tandem mirror, control the electron axial heat flow. Measurements of the spatial and temporal variations of the plasma potential are, therefore, important to the understanding of confinement in a tandem mirror. In this paper we discuss potential formation in a thermal barrier tandem mirror and examine the diagnostics and data obtained on the TMX-U device, including measurements of the thermal barrier potential profile using a diagnostic neutral beam and charged particle energy-spectroscopy. We then describe the heavy ion beam probe and other new plasma potential diagnostics that are under development for TMX-U and MFTF-B and examine problem areas where additional diagnostic development is desirable

  7. Hall-magnetohydrodynamic waves in flowing ideal incompressible solar-wind plasmas

    International Nuclear Information System (INIS)

    Zhelyazkov, I

    2010-01-01

    It is well established now that the solar atmosphere, from the photosphere to the corona and the solar wind, is a highly structured medium. Satellite observations have confirmed the presence of steady flows there. Here, we investigate the propagation of magnetohydrodynamic (MHD) eigenmodes (kink and sausage surface waves) travelling along an ideal incompressible flowing plasma cylinder (flux tube) surrounded by a flowing plasma environment in the framework of the Hall magnetohydrodynamics. The propagation characteristics of the waves are studied in a reference frame moving with the mass flow outside the tube. In general, the flows change the waves' phase velocities compared with their magnitudes in a static MHD flux tube and the Hall effect extends the number of the possible wave dispersion curves. It turns out that while the kink waves, considered in the context of the standard magnetohydrodynamics, are unstable against the Kelvin-Helmholtz instability, they become stable when the Hall term in the generalized Ohm's law is taken into account. The sausage waves are stable in both considerations. All results concerning the waves' propagation and their stability/instability status are obtained on the basis of the linearized Hall-magnetohydrodynamic equations and are applicable mainly to the solar wind plasmas.

  8. Production of free radical by magnetized sheet plasma with vertical gas-flow

    International Nuclear Information System (INIS)

    Tonegawa, Akira; Takatori, Masahiko; Kawamura, Kazutaka

    1995-01-01

    Free radicals play an important role in plasma processing, environment problem, and space plasma and so on because of their outstanding physical properties. Although much work has been done on the free radicals in the reactive plasma, very little is known about the production mechanism of the free radicals against various plasma parameters. To overcome this problem, we have proposed to do a new system of a magnetized sheet plasma with vertical gas-flow. The sheet plasma is a special type of strongly magnetized highly ionized slab plasma. This system is controlled to the parameters of radicals and plasma independently. Therefore, it is possible to make a quantitative analysis of free radicals as the simple one. In this paper, we describe the magnetized sheet plasma with vertical gas-flow system and report the preliminary results of production of the free radical. In particular, we show to produce and control the OH free radical which has been the most commonly studied combustion species

  9. Simulation of rarefied low pressure RF plasma flow around the sample

    Science.gov (United States)

    Zheltukhin, V. S.; Shemakhin, A. Yu

    2017-01-01

    The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 103 K, in the plasma jet is (3.2-10) • 102 K, the degree of ionization is 10-7-10-5, electron density is 1015-1019 m-3. For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out.

  10. The numerical simulation of plasma flow in cylindrical resonant cavity of microwave plasma thruster

    International Nuclear Information System (INIS)

    Tang, J.-L.; He, H.-Q; Mao, G.-W.

    2004-01-01

    Microwave Plasma Thruster (MPT) is an electro-thermal propulsive device. MPT consists of microwave generator, gas storing and supplying system, resonant cavity and accelerative nozzle. It generates free-floating plasma brought by the microwave discharge breakdown gas in the resonant cavity, and the plasma exhausted from nozzle produces thrust. MPT has prospective application in spacecraft because of its advantages of high thrust, moderate specific impulse and high efficiency. In this paper, the numerical simulation of the coupling flow field of microwave plasma in resonant cavity under different frequencies will be discussed. The results of numerical simulation are as follows: 1) When the resonant model TM 011 was used, the higher the microwave frequency was, the smaller the size of MPT. The distribution of the electromagnetic field in small cavity, however, remain unchanged. 2) When the resonant model was used, the distribution of the temperature, the pressure and the electronic density in the resonant cavity remained unchanged under different resonant frequencies. 3) When the resonant frequency was increased with a fixed pressure distribution in a small cavity, compare to the MPT with lower frequency, the gas flow rate, the microwave power and the nozzle throat diameter of MPT all decreased. 4) The electromagnetic field in the cylindrical resonant cavity for all MPT with different frequencies was disturbed by the plasma formation. The strong disturbance happened in the region close to the plasma. (author)

  11. Modification of SrTiO3 single-crystalline surface after plasma flow treatment

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Alexandr A.; Weissbach, Torsten; Leisegang, Tilmann; Meyer, Dirk C. [Institut fuer Strukturphysik, Technische Universitaet Dresden, 01062 Dresden (Germany); Kulagin, Nikolay A. [Kharkiv National University for Radioelectronics, av. Shakespeare 6-48, 61045 Kharkiv (Ukraine); Langer, Enrico [Institut fuer Festkoerperphysik, Technische Universitaet Dresden, 01062 Dresden (Germany)

    2009-07-01

    Surface of pure and transition metal-doped SrTiO3(STO) single crystals before and after hydrogen plasma-flow treatment (energy of 5..20 J/cm2) is investigated by wide-angle X-ray diffraction (WAXRD), fluorescence X-ray absorption near edge structure (XANES) and scanning electron microscopy (SEM) techniques. Plasma treatment results in the formation of a textured polycrystalline layer at the surface of the single-crystalline samples with different orientation. The formation of the quasi-ordered structures consisting of nanoscale-sized pyramids is observed by SEM. XANES evidences the change of the valency of the part of Ti4+ to Ti3+ due to the plasma treatment. The data obtained together with results of X-ray spectroscopy measurements gives evidences of the change of stoichiometry of the STO samples resulting in a change of their physical properties after plasma treatment.

  12. Tribological properties of high-speed steel treated by compression plasma flow

    International Nuclear Information System (INIS)

    Cherenda, K.K.; Uglov, V.V.; Anishchik, V.M.; Stalmashonak, A.K.; Astashinski, V.M.

    2004-01-01

    Full text: The investigation of tribological properties of two high-speed steels AISI M2 and AISI Tl treated by the nitrogen compression plasma flow was the main aim of this work. Two types of samples were investigated before and after quenching. The plasma flow was received in a magneto-plasma compressor. The impulse duration was ∼100 μs, the number of impulses varied in the range of 1-5, the nitrogen pressure in the chamber was 400-4000 Pa, the energy absorbed by the sample was 2-10 J/cm 2 per impulse. Tribological properties were examined by means of a tribometer TAYl under conditions of dry friction. The Vickers's microhardness was measured by a hard meter PMT3. X-ray diffraction analysis, Auger electron spectroscopy, scanning electron microscopy and energy dispersion microanalysis were used for samples characterization. The earlier conducted investigations showed that the compression plasma flow suited well for the improvement of tribological properties of iron and low-alloyed steels due to the formation of hardening nitrides in the near surface layer. It was found that in the case of high-speed steels only not quenched samples had increased hardness after treatment. The latter can be explained by the formation of hardening nitrides though the phase analysis did not clearly reveal their presence. The element composition confirmed the presence of nitrogen in the surface layer with the concentration up to 30 at. %. The treatment of quenched samples almost always resulted in the hardness decrease due to the dissolution or partial dissolution of alloying elements carbides: M 6 C, MC, M 23 C 6 . The rate of carbides dissolution increased with the growth of the energy absorbed by the sample. The treated samples showed a lower value of the friction coefficient than the untreated one. It could be explained by the formation of nitrogenous austenite which was found out by the phase analysis. At the same time the compression plasma flow strongly influenced surface

  13. Effect of Dielectric Barrier Discharge Plasma Actuators on Non-equilibrium Hypersonic Flows

    Science.gov (United States)

    2014-10-28

    results for MIG with the US3D code devel- oped at the University of Minnesota.61 US3D is an unstruc- tured CFD code for hypersonic flow solution used...Effect of dielectric barrier discharge plasma actuators on non-equilibrium hypersonic flows Ankush Bhatia,1 Subrata Roy,1 and Ryan Gosse2 1Applied...a cylindrical body in Mach 17 hypersonic flow is presented. This application focuses on using sinusoidal dielectric barrier discharge plasma actuators

  14. Measurement of thermal plasma jet temperature and velocity by laser light lineshape analysis

    International Nuclear Information System (INIS)

    Snyder, S.C.; Reynolds, L.D.

    1991-01-01

    Two important parameters of thermal plasma jets are kinetic or gas temperatures and flow velocity. Gas temperatures have been traditionally measured using emission spectroscopy, but this method depends on either the generally unrealistic assumption of the existence of local thermodynamic equilibrium (LTE) within the plasma, or the use of various non-LTE or partial LTE models to relate the intensity of the emission lines to the gas temperature. Plasma jet velocities have been measured using laser Doppler velocimetry on particles injected into the plasma. However, this method is intrusive and it is not known how well the particle velocities represent the gas velocity. Recently, plasma jet velocities have been measured from the Doppler shift of laser light scattered by the plasma. In this case, the Doppler shift was determined from the difference in the transmission profile of a high resolution monochromator between red shifted and blue shifted scattered light. A direct approach to measuring localized temperatures and velocities is afforded by high resolution scattered light lineshape measurements. The linewidth of laser light scattered by atoms and ions can be related to the kinetic temperature without LTE assumptions, while a shift in the peak position relative to the incident laser lineshape yields the gas velocity. We report in this paper work underway to measure gas temperatures and velocities in an argon thermal plasma jet using high resolution lineshape analysis of scattered laser light

  15. HF DBD plasma actuators for reduction of cylinder noise in flow

    Science.gov (United States)

    Kopiev, V. F.; Kazansky, P. N.; Kopiev, V. A.; Moralev, I. A.; Zaytsev, M. Yu

    2017-11-01

    Surface high frequency dielectric barrier discharge (HF DBD) was used to reduce flow-induced noise, radiated by circular cylinder in cross flow. Effect of HF DBD actuators is studied for flow velocity up to 80 m s-1 (Reynolds numbers up to 2.18 · 105), corresponding to the typical aircraft landing approach speed. Noise measurements were performed by microphone array in anechoic chamber; averaged flow parameters were studied by particle image velocimetry (PIV). Actuator was powered by high-frequency voltage in hundreds kHz range in steady or modulated mode with the modulation frequency of 0.3-20 kHz (Strouhal number St of 0.4 to 20). It is demonstrated that upstream directed plasma actuators are able to reduce the vortex noise of a cylinder by 10 dB. Noise reduction is accompanied by significant reorganization of the wake behind a cylinder, decreasing both wake width and turbulence level. The physical mechanism related to broadband noise control by HF DBD actuator is also discussed.

  16. 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)

  17. Methodology of modeling and measuring computer architectures for plasma simulations

    Science.gov (United States)

    Wang, L. P. T.

    1977-01-01

    A brief introduction to plasma simulation using computers and the difficulties on currently available computers is given. Through the use of an analyzing and measuring methodology - SARA, the control flow and data flow of a particle simulation model REM2-1/2D are exemplified. After recursive refinements the total execution time may be greatly shortened and a fully parallel data flow can be obtained. From this data flow, a matched computer architecture or organization could be configured to achieve the computation bound of an application problem. A sequential type simulation model, an array/pipeline type simulation model, and a fully parallel simulation model of a code REM2-1/2D are proposed and analyzed. This methodology can be applied to other application problems which have implicitly parallel nature.

  18. Tripolar vortices of dust-drift waves in dusty plasma with shear flow

    International Nuclear Information System (INIS)

    Chen Yinhua; Wang Ge

    2002-01-01

    Nonlinear equations governing dust-drift waves in magnetized dusty plasma with transverse shear flow are derived. For the specific profiles of flow and the plasma equilibrium density, a new type of solution in the form of tripolar vortices is found. The results show that the peak magnitude of tripolar vortices increases with increasing shear intensity and dust content

  19. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    International Nuclear Information System (INIS)

    Pinchuk, M; Kurakina, N; Spodobin, V; Stepanova, O

    2017-01-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow. (paper)

  20. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  1. Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

    International Nuclear Information System (INIS)

    Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

    2010-01-01

    Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

  2. POD analysis of flow over a backward-facing step forced by right-angle-shaped plasma actuator.

    Science.gov (United States)

    Wang, Bin; Li, Huaxing

    2016-01-01

    This study aims to present flow control over the backward-facing step with specially designed right-angle-shaped plasma actuator and analyzed the influence of various scales of flow structures on the Reynolds stress through snapshot proper orthogonal decomposition (POD). 2D particle image velocimetry measurements were conducted on region (x/h = 0-2.25) and reattachment zone in the x-y plane over the backward-facing step at a Reynolds number of Re h  = 27,766 (based on step height [Formula: see text] and free stream velocity [Formula: see text]. The separated shear layer was excited by specially designed right-angle-shaped plasma actuator under the normalized excitation frequency St h  ≈ 0.345 along the 45° direction. The spatial distribution of each Reynolds stress component was reconstructed using an increasing number of POD modes. The POD analysis indicated that the flow dynamic downstream of the step was dominated by large-scale flow structures, which contributed to streamwise Reynolds stress and Reynolds shear stress. The intense Reynolds stress localized to a narrow strip within the shear layer was mainly affected by small-scale flow structures, which were responsible for the recovery of the Reynolds stress peak. With plasma excitation, a significant increase was obtained in the vertical Reynolds stress peak. Under the dimensionless frequencies St h  ≈ 0.345 and [Formula: see text] which are based on the step height and momentum thickness, the effectiveness of the flow control forced by the plasma actuator along the 45° direction was ordinary. Only the vertical Reynolds stress was significantly affected.

  3. A new facility for studying plasma interacting with flowing liquid lithium surface

    International Nuclear Information System (INIS)

    Cao, X.; Ou, W.; Tian, S.; Wang, C.; Zhu, Z.; Wang, J.; Gou, F.; Yang, D.; Chen, S.

    2014-01-01

    A new facility to study plasmas interacting with flowing liquid lithium surface was designed and is constructing in Sichuan University. The integrated setup includes the liquid lithium circulating part and linear high density plasma generator. The circulating part is consisted of main loop, on-line monitor system, lithium purification system and temperature programmed desorption system. In our group a linear high density plasma generator was built in 2012. Three coils were mounted along the vessel to produce an axial magnetic field inside. The magnetic field strength is up to 0.45 T and work continuously. Experiments on plasmas interacting with free flowing liquid lithium surface will be performed

  4. Ion collection by probing objects in flowing magnetized plasmas

    International Nuclear Information System (INIS)

    Kyu-Sun, Chung.

    1989-04-01

    A new one-dimensional collisionless kinetic model is developed for the flow of ions to probing structures in drifting plasmas. The cross-field flow into the presheath is modelled by accounting consistently for particle exchange between the collection flux tube and the outer plasma. Numerical solutions of the self-consistent plasma/sheath equations are obtained with arbitrary external ion temperature and parallel plasma flow velocity. Results are presented of the spatial dependence of the ion distribution function as well as its moments (density, particle flux, temperature, and power flux). The ion current to the probe is obtained and the ratio of the upstream to downstream currents is found to be well represented by the form R = exp[Ku d ], where K = 1.66 for T i = T e and u d is the drift velocity in units of (T e /m i ) 1/2 . The results agree well with comparable recent fluid calculations but show substantial deviations from other models which ignore particle exchange out of the presheath. No evidence is found of the formation of shocks in the downstream wake, contrary to the implications of some fluid theories. We have also extended the previous kinetic model by generalizing cross-field transport and adding ionization to the source of the Boltzmann equation along the presheath. Ion sheath current density and ratio(R) of upstream to downstream current are obtained as a function of plasma drift velocity, equivalent viscosity, ion temperature, and ionization rate. Constants(K) in the form R = exp[Ku d ] are obtained in terms of viscosity, ion temperature, and ionization rate. The effect of an electrical bias applied to the object on the presheath characteristics is discussed

  5. Simulation of rarefied low pressure RF plasma flow around the sample

    International Nuclear Information System (INIS)

    Zheltukhin, V S; Shemakhin, A Yu

    2017-01-01

    The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 10 3 K, in the plasma jet is (3.2-10) • 10 2 K, the degree of ionization is 10 -7 -10 -5 , electron density is 10 15 -10 19 m -3 . For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out. (paper)

  6. Flow injection analysis in inductively coupled plasma spectrometry

    International Nuclear Information System (INIS)

    Rosias, Maria F.G.G.

    1995-10-01

    The main features of flow injection analysis (FIA) as contribution to the inductively coupled plasma (Icp) spectrometry are described. A systematic review of researches using the combined FIA-Icp and the benefits of this association are presented. Flow systems were proposed to perform on-line Icp solution management for multielemental determination by atomic emission spectrometry (Icp-AES) or mass spectrometry. The inclusion of on-line ion exchangers in flow systems for matrix separation and/or analyte preconcentration are presented. Together with those applications the new advent of instruments with facilities for multielement detection on flow injection signals are described. (author). 75 refs., 19 figs

  7. Plasma equilibria and stationary flows in axisymmetric systems. Pt. 1

    International Nuclear Information System (INIS)

    Zelazny, R.; Stankiewicz, R.; Potempski, S.

    1988-05-01

    During discharges within a tokamak device such as JET fluctuations are observed in the plasma, of plasma density, temperature, electric potential and of the magnetic field. These fluctuations have complicated structure and are linked with different kinds of instabilities. However, it is not clear which instabilities are most important in determining the behaviour of the plasma. A comprehensive numerical theory which can predict the effect of the instabilities on the transport of plasma in axisymmetric systems has been sought using the static Grad-Shafranov-Schlueter (SGSS) equation as a basis. However, the static equation was over simplified for the situation in JET with additional heating giving rise to large toroidal flows, and an extended equation (EGSS) was developed. The results of the study include the discovery of algebraic branches of solutions to the EGSS equation even for very small poloidal flows, solutions to the inverse problem for the SGSS and EGSS equations using Fourier decomposition, classification of the boundary condition at the magnetic axis, demonstration of a visible effect of the poloidal flow on the separation of the density surface and the magnetic surface an indication of the existence of multiple branches of solutions to the EGSS and SGSS equations and their relation to stability properties. (U.K.)

  8. Enthalpy probe measurements and three-dimensional modelling on air plasma jets generated by a non-transferred plasma torch with hollow electrodes

    International Nuclear Information System (INIS)

    Kim, Keun Su; Park, Jin Myung; Choi, Sooseok; Kim, Jongin; Hong, Sang Hee

    2008-01-01

    Thermal flow characteristics of air plasma jets generated by a non-transferred plasma torch with hollow electrodes are experimentally and numerically investigated in order to provide more reliable scientific and technical information, which has been insufficient for their practical applications to material and environmental industries. In this work, a thermal plasma torch of hollow electrode type is first designed and fabricated, and similarity criteria for predicting operational conditions for the scale-up to high-power torches are derived from the arc voltage characteristics measured with various operating and geometry conditions of the torch. The thermal flow characteristics of air plasma jets ejected from the torch are measured by enthalpy probe diagnostics and turn out to have relatively low temperatures of around 3000-7000 K, but show features of other unique properties, such as high energy flux, broad high temperature region and long plasma jet with moderate axial velocity, which are promising for their applications to material syntheses and hazardous waste treatments. Such high enthalpy at a relatively low temperature of air thermal plasma compared with the argon one is due to the high thermal energy residing in the vibrational and rotational states and oxygen dissociation, besides the translational states in monatomic gases such as argon. It is expected that this high specific enthalpy of the air plasma will enable material and environmental industries to treat a large amount of precursors and waste materials effectively at a lower temperature for a longer residence time by the low plasma velocity. It is also found from the measurements that the turbulence intensity influenced by the size of the electrode diameter has a significant effect on the axial and radial profiles of plasma jet properties and that a longer plasma jet is more readily achievable with a larger electrode diameter reducing the turbulence intensity in the external region of the torch. In

  9. Plasma flow to a surface using the iterative Monte Carlo method

    International Nuclear Information System (INIS)

    Pitcher, C.S.

    1994-01-01

    The iterative Monte Carlo (IMC) method is applied to a number of one-dimensional plasma flow problems, which encompass a wide range of conditions typical of those present in the boundary of magnetic fusion devices. The kinetic IMC method of solving plasma flow to a surface consists of launching and following particles within a grid of 'bins' into which weights are left according to the time a particle spends within a bin. The density and potential distributions within the plasma are iterated until the final solution is arrived at. The IMC results are compared with analytical treatments of these problems and, in general, good agreement is obtained. (author)

  10. Plasma assisted measurements of alkali metal concentrations in pressurized combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R.; Haeyrinen, V. [Tampere Univ. of Technology (Finland). Dept. of Physics

    1996-12-01

    The plasma assisted method for continuous measurement of alkali concentrations in product gas flows of pressurized energy processes will be tested and applied at the 1.6 MW PFBC/G facility at Delft University of Technology in the Netherlands. During the reporting period the alkali measuring device has been tested under pressurized conditions at VTT Energy, DMT, Foster-Wheeler Energia and ABB Carbon. Measurements in Delft will be performed during 1996 after installation of the hot gas filter. The original plan for measurements in Delft has been postponed due to schedule delays in Delft. The results are expected to give information about the influence of different process conditions on the generation of alkali vapours, the comparison of different methods for alkali measurement and the specific performance of our system. This will be the first test of the plasma assisted measurement method in a gasification process. The project belongs to the Joule II extension program under contract JOU2-CT93-0431. (author)

  11. The manipulation of an unstarting supersonic flow by plasma actuator

    International Nuclear Information System (INIS)

    Im, S; Cappelli, M A; Do, H

    2012-01-01

    The manipulation of an unstarting supersonic flow is demonstrated using a dielectric barrier discharge (DBD). Experiments are carried out in a Mach 4.7 model inlet flow. Flow features, such as boundary layers and shockwaves at low freestream static pressure (1 kPa) and temperature (60 K) are visualized with Rayleigh scattering from condensed CO 2 particles. Flow unstart, initiated by mass injection, is studied for three model inlet flow configurations, distinguished by the initial conditions (untripped or tripped, plasma actuated or not) of the boundary layers. Unstart in the presence of thick, tripped boundary layers is characterized by the formation of an oblique unstart shock just upstream of a separating and propagating boundary layer. The presence of plasma actuation of this tripped boundary layer seems to arrest the boundary layer separation and leads to the formation of a quasi-stationary pseudo-shock, delaying unstart. The flow generated with DBD actuation is more characteristic of what is seen when unstart is generated in a model flow in which thin boundary layers grow naturally. Planar laser Rayleigh scattering visualizations suggest that the DBD actuation thins the tripped boundary layer over the exposed electrode region.

  12. A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

    Energy Technology Data Exchange (ETDEWEB)

    Kiuttu, G F; Degnan, J H [Phillips Lab., Kirtland AFB, NM (United States). High Energy Sources Div.; Graham, J D [Maxwell Labs., Albuquerque, NM (United States); and others

    1997-12-31

    A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 {mu}s, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10{sup 8} neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs.

  13. A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

    International Nuclear Information System (INIS)

    Kiuttu, G.F.; Degnan, J.H.

    1996-01-01

    A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 μs, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10 8 neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs

  14. Modeling, fabrication and plasma actuator coupling of flexible pressure sensors for flow separation detection and control in aeronautical applications

    Science.gov (United States)

    Francioso, L.; De Pascali, C.; Pescini, E.; De Giorgi, M. G.; Siciliano, P.

    2016-06-01

    Preventing the flow separation could enhance the performance of propulsion systems and future civil aircraft. To this end, a fast detection of boundary layer separation is mandatory for a sustainable and successful application of active flow control devices, such as plasma actuators. The present work reports on the design, fabrication and functional tests of low-cost capacitive pressure sensors coupled with dielectric barrier discharge (DBD) plasma actuators to detect and then control flow separation. Finite element method (FEM) simulations were used to obtain information on the deflection and the stress distribution in different-shaped floating membranes. The sensor sensitivity as a function of the pressure load was also calculated by experimental tests. The results of the calibration of different capacitive pressure sensors are reported in this work, together with functional tests in a wind tunnel equipped with a curved wall plate on which a DBD plasma actuator was mounted to control the flow separation. The flow behavior was experimentally investigated by particle image velocimetry (PIV) measurements. Statistical and spectral analysis, applied to the output signals of the pressure sensor placed downstream of the profile leading edge, demonstrated that the sensor is able to discriminate different ionic wind velocity and turbulence conditions. The sensor sensitivity in the 0-100 Pa range was experimentally measured and it ranged between 0.0030 and 0.0046 pF Pa-1 for the best devices.

  15. Plasma-Assisted Chemistry in High-Speed Flow

    International Nuclear Information System (INIS)

    Leonov, Sergey B.; Yarantsev, Dmitry A.; Napartovich, Anatoly P.; Kochetov, Igor V.

    2007-01-01

    Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow

  16. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    International Nuclear Information System (INIS)

    Gilmore, Mark Allen

    2017-01-01

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB's)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB's] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  17. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Mark Allen [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-02-05

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB’s)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB’s] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  18. Progress towards experimental realization of extreme-velocity flow-dominated magnetized plasmas

    Science.gov (United States)

    Weber, T. E.; Adams, C. S.; Welch, D. R.; Kagan, G.; Bean, I. A.; Henderson, B. R.; Klim, A. J.

    2017-10-01

    Interactions of flow-dominated plasmas with other plasmas, neutral gases, magnetic fields, solids etc., take place with sufficient velocity that kinetic energy dominates the dynamics of the interaction (as opposed to magnetic or thermal energy, which dominates in most laboratory plasma experiments). Building upon progress made by the Magnetized Shock Experiment (MSX) at LANL, we are developing the experimental and modeling capability to increase our ultimate attainable plasma velocities well in excess of 1000 km/s. Ongoing work includes designing new pulsed power switches, triggering, and inductive adder topologies; development of novel high-speed optical diagnostics; and exploration of new numerical techniques to specifically model the unique physics of translating/stagnating flow-dominated plasmas. Furthering our understanding of the physical mechanisms of energy conversion from kinetic to other forms, such as thermal energy, non-thermal tails/accelerated populations, enhanced magnetic fields, and radiation (both continuum and line), has wide-ranging significance in basic plasma science, astrophysics, and plasma technology applications such as inertial confinement fusion and intense radiation sources. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. LA-UR-17-25786.

  19. Measurement of flow in the scrape-off layer of TdeV

    International Nuclear Information System (INIS)

    MacLatchy, C.S.; Gunn, J.P.; Boucher, C.; Poirier, D.A.; Stansfield, B.L.; Zuzak, W.W.

    1992-01-01

    Two techniques are used to monitor the flow in the scrape-off layer of Tokamak de Varennes (TdeV); one is based on a new multipin Langmuir/Mach probe called Gundestrup while the other depends on the measurement of the upstream/downstream asymmetry of the power absorbed by a test limiter inserted into the plasma edge. Gundestrup has been used to measure the components of velocity parallel and perpendicular to the magnetic field as a function of the radial electric field. Both components vary linearly with the radial field and inversely as the magnetic field (U parallel ∝E r /B θ and U perpendicular to ∝E r /B). The pattern of power deposition on the test limiter implies that the flow is in the same direction as that measured by Gundestrup and the e-folding length for the power deposition is in agreement with Gundestrup measurements of temperature and density. The test limiter observations indicate that the flow reverses just inside the separatrix. (orig.)

  20. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  1. The Efficiency of Quartz Particles Evaporation in the Argon Plasma Flow of the RF Inductively Coupled Plasma Torch

    Directory of Open Access Journals (Sweden)

    Yu. M. Grishin

    2017-01-01

    Full Text Available Owing to high-power density and high-purity plasma, a RF inductively coupled plasma torch (ICPT is widely used both in research laboratory and in industry. The potential RF ICPT application areas are powders spheroidisation, waste treatment, thermal spraying, etc.In the last decade the investigation was focused on the treatment processes of quartz into polycrystalline silicon. An analysis of these results has shown that the increasing productivity and producing high-purity silicon can be achieved only when using the electrodeless radio-frequency induction plasma torches and in case the optimum conditions for evaporation of SiO2solid particles are realized.Optimization of the RF ICPT design and power parameters calls for a wide range of computational studies. In spite of the fact that to date a large number of efforts to calculate the evaporation efficiency of powder materials have been made, a number of issues, as applied to the problem of obtaining silicon, require further research.In this paper, we present the results of a two-dimensional numerical simulation of the heating and evaporation of quartz particles in the RF ICPT channel with axial flow of gases. The main aim is to determine how the axial position of the central tube (through which the particles are injected into the discharge zone, the dispersion of the quartz powder, the amplitude of the discharge current (and, respectively, flow regimes impact on the evaporation efficiency of quartz particles.The paper presented the numerical modeling results of heating and evaporation processes of quartz particles supplied by transporting gas to the RF ICPT channel with axial gas flow (argon. Defined the impact of the axial position of the central tube, the plasma flow regime, the discharge current, the flow rate of transporting gas, and other parameters on the evaporation efficiency of quartz particles.It is shown that the evaporation efficiency of particles reaches its maximum when their

  2. The spherical segmented Langmuir probe in a flowing thermal plasma: numerical model of the current collection

    Directory of Open Access Journals (Sweden)

    E. Séran

    2005-07-01

    Full Text Available The segmented Langmuir probe (SLP has been recently proposed by one of the authors (Lebreton, 2002 as an instrument to derive the bulk velocity of terrestrial or planetary plasmas, in addition to the electron density and temperature that are routinely measured by Langmuir probes. It is part of the scientific payload on the DEMETER micro-satellite developed by CNES. The basic concept of this probe is to measure the current distribution over the surface using independent collectors under the form of small spherical caps and to use the angular anisotropy of these currents to obtain the plasma bulk velocity in the probe reference frame. In order to determine the SLP capabilities, we have developed a numerical PIC (Particles In Cell model which provides a tool to compute the distribution of the current collected by a spherical probe. Our model is based on the simultaneous determination of the charge densities in the probe sheath and on the probe surface, from which the potential distribution in the sheath region can be obtained. This method is well adapted to the SLP problem and has some advantages since it provides a natural control of the charge neutrality inside the simulation box, allows independent mesh sizes in the sheath and on the probe surface, and can be applied to complex surfaces. We present in this paper initial results obtained for plasma conditions corresponding to a Debye length equal to the probe radius. These plasma conditions are observed along the Demeter orbit. The model results are found to be in very good agreement with those published by Laframboise (1966 for a spherical probe in a thermal non-flowing plasma. This demonstrates the adequacy of the computation method and of the adjustable numerical parameters (size of the numerical box and mesh, time step, number of macro-particles, etc. for the considered plasma-probe configuration. We also present the results obtained in the case of plasma flowing with mesothermal conditions

  3. The spherical segmented Langmuir probe in a flowing thermal plasma: numerical model of the current collection

    Directory of Open Access Journals (Sweden)

    E. Séran

    2005-07-01

    Full Text Available The segmented Langmuir probe (SLP has been recently proposed by one of the authors (Lebreton, 2002 as an instrument to derive the bulk velocity of terrestrial or planetary plasmas, in addition to the electron density and temperature that are routinely measured by Langmuir probes. It is part of the scientific payload on the DEMETER micro-satellite developed by CNES. The basic concept of this probe is to measure the current distribution over the surface using independent collectors under the form of small spherical caps and to use the angular anisotropy of these currents to obtain the plasma bulk velocity in the probe reference frame. In order to determine the SLP capabilities, we have developed a numerical PIC (Particles In Cell model which provides a tool to compute the distribution of the current collected by a spherical probe. Our model is based on the simultaneous determination of the charge densities in the probe sheath and on the probe surface, from which the potential distribution in the sheath region can be obtained. This method is well adapted to the SLP problem and has some advantages since it provides a natural control of the charge neutrality inside the simulation box, allows independent mesh sizes in the sheath and on the probe surface, and can be applied to complex surfaces. We present in this paper initial results obtained for plasma conditions corresponding to a Debye length equal to the probe radius. These plasma conditions are observed along the Demeter orbit. The model results are found to be in very good agreement with those published by Laframboise (1966 for a spherical probe in a thermal non-flowing plasma. This demonstrates the adequacy of the computation method and of the adjustable numerical parameters (size of the numerical box and mesh, time step, number of macro-particles, etc. for the considered plasma-probe configuration. We also present the results obtained in the case of plasma flowing with mesothermal conditions

  4. Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

    Directory of Open Access Journals (Sweden)

    Di Jin

    2015-02-01

    Full Text Available The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 × 1012 W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

  5. Rational surfaces, ExB sheared flows and transport interplay in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, Carlos; Pedrosa, Maria A.; Erents, Kevin

    2001-01-01

    Experimental evidence of a strong interplay between magnetic topology (rational surfaces) and the generation of ExB sheared flows has been observed in the plasma edge region of stellarator (TJ-II) and tokamak (JET) devices. Constant and varying in time ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. The plasma conditions where this has been observed are clearly below the power threshold to trigger the formation of transport barriers. Flows driven by fluctuations are candidates to explain these experimental results. (author)

  6. Energy Flow in Dense Off-Equilibrium Plasma

    Science.gov (United States)

    2016-07-15

    brings the electron density and light emission into LTE at the measured spectral temperature while leaving the ions cold. Because of their large mass... measurements of ionization potential lowering and collision times indense plasmas, allowing us to distinguish between competing dense-plasma models...Hydrodynamic analysis of shockwaves generated by sparks yielded similar measurements ina different, more accessible system. Ultra-fast observations

  7. EDITORIAL: Measurement techniques for multiphase flows Measurement techniques for multiphase flows

    Science.gov (United States)

    Okamoto, Koji; Murai, Yuichi

    2009-11-01

    Research on multiphase flows is very important for industrial applications, including power stations, vehicles, engines, food processing and so on. Multiphase flows originally have nonlinear features because of multiphase systems. The interaction between the phases plays a very interesting role in the flows. The nonlinear interaction causes the multiphase flows to be very complicated. Therefore techniques for measuring multiphase flows are very useful in helping to understand the nonlinear phenomena. The state-of-the-art measurement techniques were presented and discussed at the sixth International Symposium on Measurement Techniques for Multiphase Flows (ISMTMF2008) held in Okinawa, Japan, on 15-17 December 2008. This special feature of Measurement Science and Technology includes selected papers from ISMTMF2008. Okinawa has a long history as the Ryukyus Kingdom. China, Japan and many western Pacific countries have had cultural and economic exchanges through Okinawa for over 1000 years. Much technical and scientific information was exchanged at the symposium in Okinawa. The proceedings of ISMTMF2008 apart from these special featured papers were published in Journal of Physics: Conference Series vol. 147 (2009). We would like to express special thanks to all the contributors to the symposium and this special feature. This special feature will be a milestone in measurement techniques for multiphase flows.

  8. Plasma fluctuation measurements in tokamaks using beam-plasma interactions

    International Nuclear Information System (INIS)

    Fonck, R.J.; Duperrex, P.A.; Paul, S.F.

    1990-01-01

    High-frequency observations of light emitted from the interactions between plasma ions and injected neutral beam atoms allow the measurement of moderate-wavelength fluctuations in plasma and impurity ion densities. To detect turbulence in the local plasma ion density, the collisionally excited fluorescence from a neutral beam is measured either separately at several spatial points or with a multichannel imaging detector. Similarly, the role of impurity ion density fluctuations is measured using charge exchange recombination excited transitions emitted by the ion species of interest. This technique can access the relatively unexplored region of long-wavelength plasma turbulence with k perpendicular ρ i much-lt 1, and hence complements measurements from scattering experiments. Optimization of neutral beam geometry and optical sightlines can result in very good localization and resolution (Δx≤1 cm) in the hot plasma core region. The detectable fluctuation level is determined by photon statistics, atomic excitation processes, and beam stability, but can be as low as 0.2% in a 100 kHz bandwidth over the 0--1 MHz frequency range. The choices of beam species (e.g., H 0 , He 0 , etc.), observed transition (e.g., H α , L α , He I singlet or triplet transitions, C VI Δn=1, etc.) are dictated by experiment-specific factors such as optical access, flexibility of beam operation, plasma conditions, and detailed experimental goals. Initial tests on the PBX-M tokamak using the H α emissions from a heating neutral beam show low-frequency turbulence in the edge plasma region

  9. A note on supersonic flow control with nanosecond plasma actuator

    Science.gov (United States)

    Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

    2018-04-01

    A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

  10. Plasma kinetics around a dust grain in an ion flow

    International Nuclear Information System (INIS)

    Maiorov, S.A.; Vladimirov, S.V.; Cramer, N.F.

    2000-01-01

    Full text: In a typical laboratory discharge, dust particles are negatively charged and usually levitate in the sheath or pre-sheath region under the balance of gravitational, electrostatic (due to the sheath electric field) and plasma (such as the ion drag) forces. The ion flow provides not only a direct (dragging) influence, but is also responsible for the generation of associated collective plasma processes which can strongly affect the vertical arrangement of the dust grains. The complete problem of the plasma dynamics around a macroscopic body in the presence of plasma flows is highly nonlinear and therefore its numerical analysis is of major importance. Among various numerical methods, direct integration of the equations of motion of the plasma particles represents a numerical experiment whose significance approaches experiments in the laboratory. Here, we present for the first time the results of a self-consistent molecular dynamics (MD) three-dimensional (3D) simulation of the kinetics of plasma particles (electrons and ions) around a dust grain, taking into account the dust charging. The core of the method includes consideration of the time evolution of the system consisting of positively ('ions') and negatively ('electrons') charged particles confined in a simulation box together with a macroscopic absorbing grain ('dust particle') with infinite mass and an initial (negative) charge. The ions are introduced in the system as a uniform flow defined by its Mach number and the ion temperature. The paths of the ions and electrons are determined through numerical integration of the equations of motion. We demonstrate that the plasma kinetics around a dust grain in the presence of an ion flow involves a strong ion focusing behind the grain. We have also confirmed that the most important of the processes involved is the ion time-scale; the kinetics of the electrons follows a Boltzmann distribution with good agreement. We note that the time constraints involved

  11. Spectroscopic study of atmospheric pressure 915 MHz microwave plasma at high argon flow rate

    International Nuclear Information System (INIS)

    Miotk, R; Hrycak, B; Jasinski, M; Mizeraczyk, J

    2012-01-01

    In this paper results of optical emission spectroscopic (OES) study of atmospheric pressure microwave 915 MHz argon plasma are presented. The plasma was generated in microwave plasma source (MPS) cavity-resonant type. The aim of research was determination of electron excitation temperature T exc gas temperature Tg and electron number density n e . All experimental tests were performed with a gas flow rate of 100 and 200 l/min and absorbed microwave power PA from 0.25 to 0.9 kW. The emission spectra at the range of 300 – 600 nm were recorded. Boltzmann plot method for argon 5p – 4s and 5d – 4p transition lines allowed to determine T exc at level of 7000 K. Gas temperature was determined by comparing the measured and simulated spectra using LIFBASE program and by analyzing intensities of two groups of unresolved rotational lines of the OH band. Gas temperature ranged 600 – 800 K. The electron number density was determined using the method based on the Stark broadening of hydrogen H β line. The measured n e rang ed 2 × 10 15 − 3.5×10 15 cm −3 , depending on the absorbed microwave power. The described MPS works very stable with various working gases at high flow rates, that makes it an attractive tool for different gas processing.

  12. An Experimental Study of Continuous Plasma Flows Driven by a Confined Arc in a Transverse Magnetic Field

    Science.gov (United States)

    Barger, R. L.; Brooks, J. D.; Beasley, W. D.

    1961-01-01

    A crossed-field, continuous-flow plasma accelerator has been built and operated. The highest measured velocity of the flow, which was driven by the interaction of the electric and magnetic fields, was about 500 meters per second. Some of the problems discussed are ion slip, stability and uniformity of the discharge, effect of the magnetic field on electron emission, use of preionization, and electrode contamination.

  13. A comparison of two nuclear-medical techniques for effective renal plasma flow determination in rabbits: Radiation controlled infusion-pump and whole-body measurement according to Oberhausen

    International Nuclear Information System (INIS)

    Mayer-Wehrstein, R.

    1981-01-01

    Two nuclear techniques were investigated for determination of the effective renal plasma flow with J-131-Hippuran in rabbits: whole-body measurement according to Oberhausen and clearance determination with a radiation controlled feed back infusion pump. In the first method the clearance determination follows after a single injection of the testing substance in the decreasing phase of the blood level, in the second method a constant blood level of the testing substance is maintained. A technique was developed for the determination of the blood-tissue ratio by considering the values determined by the constant blood level. This way the exact clearance values were computet for the decreasing plasma level. Nineteen clearance determinations were performed in rabbits altogether. (orig.) [de

  14. A study of direct-current surface discharge plasma for a Mach 3 supersonic flow control

    Science.gov (United States)

    Shin, Jichul

    A direct-current, non-equilibrium surface glow discharge plasma in the presence of a Mach 2.85 flow is studied experimentally for flow control applications. The discharge is generated with pin-like electrodes flush mounted on a ceramic plate with sustaining currents from 25 mA to 300 mA. In the presence of a supersonic flow, two distinct discharge modes - diffuse and constricted - are observed depending on the flow and discharge operating conditions. In cathode upstream location, both diffuse and constricted discharges are observed while in cathode downstream location, the discharge mostly exhibits either constricted mode or bistable mixed mode. The effect of the discharge on the flow ("plasma actuation'') is characterized by the appearance of a weak shock wave in the vicinity of the discharge. The shock is observed at low powers (˜10 W) for the diffuse discharge mode but is absent for the higher power (˜100 W) constricted mode. High speed laser schlieren imaging suggests that the diffuse mode plasma actuation is rapid as it occurs on a time scale that is less than 100 microsec. Rotational (gas) and vibrational temperatures within the discharge are estimated by emission spectral line fits of N 2 and N+2 rovibronic bands near 365-395 nm. The electronic temperatures are estimated by using the Boltzmann plot method for Fe(I) atomic lines. Rotational temperatures are found to be high (˜1500 K) in the absence of a flow but drop sharply (˜500 K) in the presence of a supersonic flow for both the diffuse and constricted discharge modes. The vibrational and electronic temperatures are measured to be about 3000 K and 1.25 eV (14500 K), respectively, and these temperatures are the same with and without flow. The gas (rotational) temperature spatial profiles above the cathode surface are found to be similar for the diffuse and constricted modes indicating that dilatational effects due to gas heating are similar. However, complete absence of flow actuation for the

  15. Localized fast flow disturbance observed in the plasma sheet and in the ionosphere

    Directory of Open Access Journals (Sweden)

    R. Nakamura

    2005-02-01

    Full Text Available An isolated plasma sheet flow burst took place at 22:02 UT, 1 September 2002, when the Cluster footpoint was located within the area covered by the Magnetometers-Ionospheric Radars-All-sky Cameras Large Experiment (MIRACLE. The event was associated with a clear but weak ionospheric disturbance and took place during a steady southward IMF interval, about 1h preceding a major substorm onset. Multipoint observations, both in space and from the ground, allow us to discuss the temporal and spatial scale of the disturbance both in the magnetosphere and ionosphere. Based on measurements from four Cluster spacecraft it is inferred that Cluster observed the dusk side part of a localized flow channel in the plasma sheet with a flow shear at the front, suggesting a field-aligned current out from the ionosphere. In the ionosphere the equivalent current pattern and possible field-aligned current location show a pattern similar to the auroral streamers previously obtained during an active period, except for its spatial scale and amplitude. It is inferred that the footpoint of Cluster was located in the region of an upward field-aligned current, consistent with the magnetospheric observations. The entire disturbance in the ionosphere lasted about 10min, consistent with the time scale of the current sheet disturbance in the magnetosphere. The plasma sheet bulk flow, on the other hand, had a time scale of about 2min, corresponding to the time scale of an equatorward excursion of the enhanced electrojet. These observations confirm that localized enhanced convection in the magnetosphere and associated changes in the current sheet structure produce a signature with consistent temporal and spatial scale at the conjugate ionosphere.

  16. Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma

    Science.gov (United States)

    Khan, T. M.; Pokle, A.; Lunney, J. G.

    2018-04-01

    Two methods of atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver are described. In both methods the ablation plume, produced by a 248 nm, 20 ns excimer laser in gas, is strongly confined near the target and forms a nanoparticle aerosol. For both the flowing gas, and the atmospheric plasma from a dielectric barrier discharge plasma source, the aerosol is entrained in the flow and carried to a substrate for deposition. The nanoparticle films produced by both methods were examined by electron microscopy and optical absorption spectroscopy. With plasma assistance, the deposition rate was significantly enhanced and the film morphology altered. With argon gas, isolated nanoparticles of 20 nm size were obtained, whereas in argon plasma, the nanoparticles are aggregated in clusters of 90 nm size. Helium gas also leads to the deposition of isolated nanoparticles, but with helium plasma, two populations of nanoparticles are observed: one of rounded particles with a mean size of 26 nm and the other of faceted particles with a mean size 165 nm.

  17. Nonlinear drift waves in a dusty plasma with sheared flows

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J. [K.U. Leuven (Belgium). Center for Plasma Astrophysics; Shukla, R.K. [Ruhr-Univ. Bochum (Germany). Inst. fuer Theoretische Physik IV

    2002-01-01

    Nonlinear properties of dust-modified drift waves and dust-drift waves in a dusty magnetoplasma with equilibrium sheared flows are examined. For this purpose, the relevant nonlinear equations for drift waves are analyzed for various profiles of the perpendicular and parallel plasma flows, and a variety of nonlinear solutions (viz. single and double vortex chains accompanied with zonal flows, tripolar and global vortices), which are driven by nommiform shear flows and nommiform dust density, is presented.

  18. Nonlinear drift waves in a dusty plasma with sheared flows

    International Nuclear Information System (INIS)

    Vranjes, J.; Shukla, R.K.

    2002-01-01

    Nonlinear properties of dust-modified drift waves and dust-drift waves in a dusty magnetoplasma with equilibrium sheared flows are examined. For this purpose, the relevant nonlinear equations for drift waves are analyzed for various profiles of the perpendicular and parallel plasma flows, and a variety of nonlinear solutions (viz. single and double vortex chains accompanied with zonal flows, tripolar and global vortices), which are driven by nommiform shear flows and nommiform dust density, is presented

  19. HF DBD plasma actuators for reduction of cylinder noise in flow

    International Nuclear Information System (INIS)

    Kopiev, V F; Kopiev, V A; Zaytsev, M Yu; Kazansky, P N; Moralev, I A

    2017-01-01

    Surface high frequency dielectric barrier discharge (HF DBD) was used to reduce flow-induced noise, radiated by circular cylinder in cross flow. Effect of HF DBD actuators is studied for flow velocity up to 80 m s −1 (Reynolds numbers up to 2.18 · 10 5 ), corresponding to the typical aircraft landing approach speed. Noise measurements were performed by microphone array in anechoic chamber; averaged flow parameters were studied by particle image velocimetry (PIV). Actuator was powered by high-frequency voltage in hundreds kHz range in steady or modulated mode with the modulation frequency of 0.3–20 kHz (Strouhal number St of 0.4 to 20). It is demonstrated that upstream directed plasma actuators are able to reduce the vortex noise of a cylinder by 10 dB. Noise reduction is accompanied by significant reorganization of the wake behind a cylinder, decreasing both wake width and turbulence level. The physical mechanism related to broadband noise control by HF DBD actuator is also discussed. (paper)

  20. EFFECT OF ION ∇ B DRIFT DIRECTION ON TURBULENCE FLOW AND FLOW SHEAR

    International Nuclear Information System (INIS)

    FENZI, C; McKEE, G.R; BURRELL, K.H; CARLSTROM, T.N; FONCK, R.J; GROEBNER, R.J

    2003-01-01

    The divertor magnetic geometry has a significant effect on the poloidal flow and resulting flow shear of turbulence in the outer region of L-mode tokamak plasmas, as determined via two-dimensional measurements of density fluctuations with Beam Emission Spectroscopy on DIII-D. Plasmas with similar parameters, except that in one case the ion (del)B drift points towards the divertor X-point (lower single-null, LSN), and in the other case, the ion (del)B drift points away from the divertor X-point (upper single-null, USN), are compared. Inside of r/a=0.9, the turbulence characteristics (amplitude, flow direction, correlation lengths) are similar in both cases, while near r/a=0.92, a dramatic reversal of the poloidal flow of turbulence relative to the core flow direction is observed in plasmas with the ion (del)B drift pointing towards the divertor X-point. No such flow reversal is observed in plasmas with the ion (del)B drift pointing away from the divertor X-point. This poloidal flow reversal results in a significantly larger local shear in the poloidal turbulence flow velocity in plasmas with the ion (del)B drift pointing towards the divertor X-point. Additionally, these plasmas locally exhibit significant dispersion, with two distinct and counter-propagating turbulence modes. Likewise, the radial correlation length of the turbulence is reduced in these plasmas, consistent with biorthogonal decomposition measurements of dominant turbulence structures. The naturally occurring turbulence flow shear in these LSN plasmas may facilitate the LH transition that occurs at an input power of roughly one-half to one-third that of corresponding plasmas with the ion (del)B drift pointing away from the X-point

  1. Atmospheric-pressure plasma jets: Effect of gas flow, active species, and snake-like bullet propagation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S.; Wang, Z.; Huang, Q.; Tan, X.; Lu, X. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Ostrikov, K. [CSIRO Materials Science and Engineering, PO Box 218, Lindfield NSW 2070 (Australia); School of Physics, University of Sydney, Sydney NSW 2006 (Australia); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2013-02-15

    Cold atmospheric-pressure plasma jets have recently attracted enormous interest owing to numerous applications in plasma biology, health care, medicine, and nanotechnology. A dedicated study of the interaction between the upstream and downstream plasma plumes revealed that the active species (electrons, ions, excited OH, metastable Ar, and nitrogen-related species) generated by the upstream plasma plume enhance the propagation of the downstream plasma plume. At gas flows exceeding 2 l/min, the downstream plasma plume is longer than the upstream plasma plume. Detailed plasma diagnostics and discharge species analysis suggest that this effect is due to the electrons and ions that are generated by the upstream plasma and flow into the downstream plume. This in turn leads to the relatively higher electron density in the downstream plasma. Moreover, high-speed photography reveals a highly unusual behavior of the plasma bullets, which propagate in snake-like motions, very differently from the previous reports. This behavior is related to the hydrodynamic instability of the gas flow, which results in non-uniform distributions of long-lifetime active species in the discharge tube and of surface charges on the inner surface of the tube.

  2. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  3. Numerical analysis of the effect of plasma flow control on enhancing the aerodynamic characteristics of stratospheric screw propeller

    International Nuclear Information System (INIS)

    Cheng Yufeng; Nie Wansheng

    2012-01-01

    Based on the body force aerodynamic actuation mechanism of dielectric barrier discharge (DBD) plasma, the effect of plasma flow control on enhancing the aerodynamic characteristics of ten blade elements equably along the stratospheric screw propeller blade was numerical studied. Then the effect of plasma flow control enhancing the aerodynamic characteristics of stratospheric screw propeller was compared that by the blade element theory method. The results show that the flow separate phenomena will easily happen in the root region and top end region of screw propeller, and the blade elements in the root region of screw propeller may work on the negative attack angle condition. DBD plasma flow control can entirely restrain the faintish flow separate phenomena in middle region of screw propeller. Although DBD plasma flow control can not entirely restrain the badly flow separate phenomena in top end region of screw propeller, it also can enhance the aerodynamic characteristics of blade elements in these regions in same degree. But effect of DBD plasma flow control on enhancing the aerodynamic characteristics of the blade elements working on the negative attack angle condition is ineffectively. It can be concluded that DBD plasma flow control can enhance the aerodynamic characteristics of stratospheric screw propeller, the thrust of the whole propeller and the propeller efficiency in the case of plasma on will increases by a factor of 28.27% and 12.3% respectively compared with that in the case of plasma off studied. (authors)

  4. Sheared flow amplification by vacuum magnetic islands in stellarator plasmas

    International Nuclear Information System (INIS)

    Garcia, L.; Carreras, B. A.; Lynch, V. E.; Pedrosa, M. A.; Hidalgo, C.

    2001-01-01

    There is some experimental evidence that the E x B flows have radial structure that may be linked to rational surfaces. This flow structure may result from a self-organization process involving nonlinear flow amplification through Reynolds stress and fluctuation reduction by sheared flows. In stellarators, a large contribution to the Reynolds stress comes from the coupling of the magnetic field component of a vacuum field island with a plasma instability. In this process, the self-organization principle seems to be marginal stability for the fluctuations driving the flow

  5. Modeling, fabrication and plasma actuator coupling of flexible pressure sensors for flow separation detection and control in aeronautical applications

    International Nuclear Information System (INIS)

    Francioso, L; De Pascali, C; Siciliano, P; Pescini, E; De Giorgi, M G

    2016-01-01

    Preventing the flow separation could enhance the performance of propulsion systems and future civil aircraft. To this end, a fast detection of boundary layer separation is mandatory for a sustainable and successful application of active flow control devices, such as plasma actuators. The present work reports on the design, fabrication and functional tests of low-cost capacitive pressure sensors coupled with dielectric barrier discharge (DBD) plasma actuators to detect and then control flow separation. Finite element method (FEM) simulations were used to obtain information on the deflection and the stress distribution in different-shaped floating membranes. The sensor sensitivity as a function of the pressure load was also calculated by experimental tests. The results of the calibration of different capacitive pressure sensors are reported in this work, together with functional tests in a wind tunnel equipped with a curved wall plate on which a DBD plasma actuator was mounted to control the flow separation. The flow behavior was experimentally investigated by particle image velocimetry (PIV) measurements. Statistical and spectral analysis, applied to the output signals of the pressure sensor placed downstream of the profile leading edge, demonstrated that the sensor is able to discriminate different ionic wind velocity and turbulence conditions. The sensor sensitivity in the 0–100 Pa range was experimentally measured and it ranged between 0.0030 and 0.0046 pF Pa −1 for the best devices. (paper)

  6. Self-separation of blood plasma from whole blood during the capillary flow in microchannel

    Science.gov (United States)

    Nunna, Bharath Babu; Zhuang, Shiqiang; Lee, Eon Soo

    2017-11-01

    Self-separation of blood plasma from whole blood in microchannels is of great importance due to the enormous range of applications in healthcare and diagnostics. Blood is a multiphase complex fluid, composed of cells suspended in blood plasma. RBCs are the suspended particles whose shape changes during the flow of blood. The primary constituents of blood are erythrocytes or red blood cells (RBCs), leukocytes or white blood cells (WBCs), thrombocytes or platelets and blood plasma. The existence of RBCs in blood makes the blood a non-Newtonian fluid. The current study of separation of blood plasma from whole blood during self-driven flows in a single microchannel without bifurcation, by enhancing the capillary effects. The change in the capillary effect results in a change in contact angle which directly influences the capillary flow. The flow velocity directly influences the net force acting on the RBCs and influence the separation process. The experiments are performed on the PDMS microchannels with different contact angles by altering the surface characteristics using plasma treatment. The change in the separation length is studied during the capillary flow of blood in microchannel. Bharath Babu Nunna is a researcher in mechanical engineering and implementing the novel and innovative technologies in the biomedical devices to enhance the sensitivity of the disease diagnosis.

  7. Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

    International Nuclear Information System (INIS)

    Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

    2012-01-01

    The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

  8. Electric field measurement in the dielectric tube of helium atmospheric pressure plasma jet

    NARCIS (Netherlands)

    Sretenović, G.B.; Guaitella, O.; Sobota, A.; Krstić, I.B.; Kovačević, V.V.; Obradović, B.M.; Kuraica, M.M.

    2017-01-01

    The results of the electric field measurements in the capillary of the helium plasma jet are presented in this article. Distributions of the electric field for the streamers are determined for different gas flow rates. It is found that electric field strength in front of the ionization wave

  9. Experimental investigation of gas flow rate and electric field effect on refractive index and electron density distribution of cold atmospheric pressure-plasma by optical method, Moiré deflectometry

    Science.gov (United States)

    Khanzadeh, Mohammad; Jamal, Fatemeh; Shariat, Mahdi

    2018-04-01

    Nowadays, cold atmospheric-pressure (CAP) helium plasma jets are widely used in material processing devices in various industries. Researchers often use indirect and spectrometric methods for measuring the plasma parameters which are very expensive. In this paper, for the first time, characterization of CAP, i.e., finding its parameters such as refractive index and electron density distribution, was carried out using an optical method, Moiré deflectometry. This method is a wave front analysis technique based on geometric optics. The advantages of this method are simplicity, high accuracy, and low cost along with the non-contact, non-destructive, and direct measurement of CAP parameters. This method demonstrates that as the helium gas flow rate decreases, the refractive index increases. Also, we must note that the refractive index is larger in the gas flow consisting of different flow rates of plasma comparing with the gas flow without the plasma.

  10. A Novel Plasma-Based Fluid for Particle Image Velocimetry (PIV): In-Vitro Feasibility Study of Flow Diverter Effects in Aneurysm Model.

    Science.gov (United States)

    Clauser, Johanna; Knieps, Marius S; Büsen, Martin; Ding, Andreas; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta; Cattaneo, Giorgio

    2018-02-27

    Particle image velocimetry (PIV) is a commonly used method for in vitro investigation of fluid dynamics in biomedical devices, such as flow diverters for intracranial aneurysm treatment. Since it is limited to transparent blood substituting fluids like water-glycerol mixture, the influence of coagulation and platelet aggregation is neglected. We aimed at the development and the application of a modified platelet rich plasma as a new PIV fluid with blood-like rheological and coagulation properties. In standardized intracranial aneurysm silicone models, the effect of this new PIV plasma on the fluid dynamics before and after flow diverter implantation was evaluated and compared with water-glycerol measurements. The flow diverting effect was strongly dependent on the used fluid, with considerably lower velocities achieved using PIV plasma, despite the same starting viscosity of both fluids. Moreover, triggering coagulation of PIV plasma allowed for intra-aneurysmal clot formation. We presented the first in vitro PIV investigation using a non-Newtonian, clottable PIV plasma, demonstrating a mismatch to a standard PIV fluid and allowing for thrombus formation.

  11. A flowing plasma model to describe drift waves in a cylindrical helicon discharge

    International Nuclear Information System (INIS)

    Chang, L.; Hole, M. J.; Corr, C. S.

    2011-01-01

    A two-fluid model developed originally to describe wave oscillations in the vacuum arc centrifuge, a cylindrical, rapidly rotating, low temperature, and confined plasma column, is applied to interpret plasma oscillations in a RF generated linear magnetized plasma [WOMBAT (waves on magnetized beams and turbulence)], with similar density and field strength. Compared to typical centrifuge plasmas, WOMBAT plasmas have slower normalized rotation frequency, lower temperature, and lower axial velocity. Despite these differences, the two-fluid model provides a consistent description of the WOMBAT plasma configuration and yields qualitative agreement between measured and predicted wave oscillation frequencies with axial field strength. In addition, the radial profile of the density perturbation predicted by this model is consistent with the data. Parameter scans show that the dispersion curve is sensitive to the axial field strength and the electron temperature, and the dependence of oscillation frequency with electron temperature matches the experiment. These results consolidate earlier claims that the density and floating potential oscillations are a resistive drift mode, driven by the density gradient. To our knowledge, this is the first detailed physics model of flowing plasmas in the diffusion region away from the RF source. Possible extensions to the model, including temperature nonuniformity and magnetic field oscillations, are also discussed.

  12. Advancement of In-Flight Alumina Powder Spheroidization Process with Water Droplet Injection Using a Small Power DC-RF Hybrid Plasma Flow System

    Science.gov (United States)

    Jang, Juyong; Takana, Hidemasa; Park, Sangkyu; Nishiyama, Hideya

    2012-09-01

    The correlation between plasma thermofluid characteristics and alumina powder spheroidization processes with water droplet injection using a small power DC-RF hybrid plasma flow system was experimentally clarified. Micro-sized water droplets with a low water flow rate were injected into the tail of thermal plasma flow so as not to disturb the plasma flow directly. Injected water droplets were vaporized in the thermal plasma flow and were transported upstream in the plasma flow to the torch by the backflow. After dissociation of water, the production of hydrogen was detected by the optical emission spectroscopy in the downstream RF plasma flow. The emission area of the DC plasma jet expanded and elongated in the vicinity of the RF coils. Additionally, the emission area of RF plasma flow enlarged and was visible as red emission in the downstream RF plasma flow in the vicinity below the RF coils due to hydrogen production. Therefore, the plasma flow mixed with produced hydrogen increased the plasma enthalpy and the highest spheroidization rate of 97% was obtained at a water flow rate of 15 Sm l/min and an atomizing gas flow rate of 8 S l/min using a small power DC-RF hybrid plasma flow system.

  13. Measurements of ODAK-3K plasma device using plastic track detectors

    International Nuclear Information System (INIS)

    2010-01-01

    In this study, some testing experiments on the fusion researches with a new-constructed plasma focus (PF) device, namely ODAK-3K are reported. The device has a maximal energy input of 3 kJ and is used for both plasma and D D reaction explorations. Experiments with deuterium have shown that peak current of I p eak=39 kA flows between the electrodes at P=11.5 mbar for the operation voltage of V=14 kV. Average total neutron yield is measured around 3.3x10 5 neutrons per shot using CR-39 plastic detectors located opposite the anode inside the PF chamber

  14. Plasma flow reactor for steady state monitoring of physical and chemical processes at high temperatures.

    Science.gov (United States)

    Koroglu, Batikan; Mehl, Marco; Armstrong, Michael R; Crowhurst, Jonathan C; Weisz, David G; Zaug, Joseph M; Dai, Zurong; Radousky, Harry B; Chernov, Alex; Ramon, Erick; Stavrou, Elissaios; Knight, Kim; Fabris, Andrea L; Cappelli, Mark A; Rose, Timothy P

    2017-09-01

    We present the development of a steady state plasma flow reactor to investigate gas phase physical and chemical processes that occur at high temperature (1000 flow injector). We have modeled the system using computational fluid dynamics simulations that are bounded by measured temperatures. In situ line-of-sight optical emission and absorption spectroscopy have been used to determine the structures and concentrations of molecules formed during rapid cooling of reactants after they pass through the plasma. Emission spectroscopy also enables us to determine the temperatures at which these dynamic processes occur. A sample collection probe inserted from the open end of the reactor is used to collect condensed materials and analyze them ex situ using electron microscopy. The preliminary results of two separate investigations involving the condensation of metal oxides and chemical kinetics of high-temperature gas reactions are discussed.

  15. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    International Nuclear Information System (INIS)

    Filippi, F.; Mostacci, A.; Palumbo, L.; Anania, M.P.; Biagioni, A.; Chiadroni, E.; Ferrario, M.; Cianchi, A.; Zigler, A.

    2016-01-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC-LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 10 16 –10 17  cm −3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  16. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    Science.gov (United States)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  17. DAQ system for low density plasma parameters measurement

    International Nuclear Information System (INIS)

    Joshi, Rashmi S.; Gupta, Suryakant B.

    2015-01-01

    In various cases where low density plasmas (number density ranges from 1E4 to 1E6 cm -3 ) exist for example, basic plasma studies or LEO space environment measurement of plasma parameters becomes very critical. Conventional tip (cylindrical) Langmuir probes often result into unstable measurements in such lower density plasma. Due to larger surface area, a spherical Langmuir probe is used to measure such lower plasma densities. Applying a sweep voltage signal to the probe and measuring current values corresponding to these voltages gives V-I characteristics of plasma which can be plotted on a digital storage oscilloscope. This plot is analyzed for calculating various plasma parameters. The aim of this paper is to measure plasma parameters using a spherical Langmuir probe and indigenously developed DAQ system. DAQ system consists of Keithley source-meter and a host system connected by a GPIB interface. An online plasma parameter diagnostic system is developed for measuring plasma properties for non-thermal plasma in vacuum. An algorithm is developed using LabVIEW platform. V-I characteristics of plasma are plotted with respect to different filament current values and different locations of Langmuir probe with reference to plasma source. V-I characteristics is also plotted for forward and reverse voltage sweep generated programmatically from the source meter. (author)

  18. A microfluidic chip for blood plasma separation using electro-osmotic flow control

    International Nuclear Information System (INIS)

    Jiang, Hai; Weng, Xuan; Chon, Chan Hee; Wu, Xudong; Li, Dongqing

    2011-01-01

    In this paper, a microfluidic-based chip with two straight microchannels and five branch microchannels was designed and tested to separate blood plasma from a small sample of fresh human blood. The electro-osmotic flow method was used to control the separation of blood plasma. Blood cell removal and blood plasma extraction were realized in experiments. The efficiency of extracting blood plasma can be as high as 26%

  19. Measurement of plasma parameters

    International Nuclear Information System (INIS)

    1999-01-01

    The physics issues of the measurements of the plasma properties necessary to provide both the control and science data for achieving the goals of the ITER device are discussed. The assessment of the requirements for these measurements is first discussed, together with priorities that relate to the experimental program. Subsequently, some of the proposed measurement techniques, the plasma diagnostics, are described with particular emphasis on their implementation on ITER and their capability to meet the requirements. A judgement on the present status of the diagnostic program on ITER is provided with some indication of the research and development program necessary to demonstrate viability of techniques or their implementation. (author)

  20. Multi-instrument observations of the ionospheric counterpart of a bursty bulk flow in the near-Earth plasma sheet

    Directory of Open Access Journals (Sweden)

    A. Grocott

    2004-04-01

    Full Text Available On 07 September 2001 the Cluster spacecraft observed a "bursty bulk flow" event in the near-Earth central plasma sheet. This paper presents a detailed study of the coincident ground-based observations and attempts to place them within a simple physical framework. The event in question occurs at ~22:30 UT, some 10min after a southward turning of the IMF. IMAGE and SAMNET magnetometer measurements of the ground magnetic field reveal perturbations of a few tens of nT and small amplitude Pi2 pulsations. CUTLASS radar observations of ionospheric plasma convection show enhanced flows out of the polar cap near midnight, accompanied by an elevated transpolar voltage. Optical data from the IMAGE satellite also show that there is a transient, localised ~1 kR brightening in the UV aurora. These observations are consistent with the earthward transport of plasma in the tail, but also indicate the absence of a typical "large-scale" substorm current wedge. An analysis of the field-aligned current system implied by the radar measurements does suggest the existence of a small-scale current "wedgelet", but one which lacks the global scale and high conductivities observed during substorm expansions.

    Key words. Ionosphere (auroral ionosphere; ionospheremagnetosphere interactions; plasma convection

  1. Tomographic multiphase flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Saetre, C., E-mail: camilla@ift.uib.no [Department of Physics and Technology, University of Bergen (Norway); Michelsen Centre for Industrial Measurement Science and Technology (Norway); Johansen, G.A. [Department of Physics and Technology, University of Bergen (Norway); Michelsen Centre for Industrial Measurement Science and Technology (Norway); Tjugum, S.A. [Michelsen Centre for Industrial Measurement Science and Technology (Norway); Roxar Flow Measurement, Bergen (Norway)

    2012-07-15

    Measurement of multiphase flow of gas, oil and water is not at all trivial and in spite of considerable achievements over the past two decades, important challenges remain (). These are related to reducing measurement uncertainties arising from variations in the flow regime, improving long term stability and developing new means for calibration, adjustment and verification of the multiphase flow meters. This work focuses on the first two issues using multi gamma beam (MGB) measurements for identification of the type of flow regime. Further gamma ray tomographic measurements are used for reference of the gas/liquid distribution. For the MGB method one Am-241 source with principal emission at 59.5 keV is used because this relatively low energy enables efficient collimation and thereby shaping of the beams, as well as compact detectors. One detector is placed diametrically opposite the source whereas the second is positioned to the side so that this beam is close to the pipe wall. The principle is then straight forward to compare the measured intensities of these detectors and through that identify the flow pattern, i.e. the instantaneous cross-sectional gas-liquid distribution. The measurement setup also includes Compton scattering measurements, which can provide information about the changes in the water salinity for flow segments with high water liquid ratio and low gas fractions. By measuring the transmitted intensity in short time slots (<100ms), rapid regime variations are revealed. From this we can select the time sections suitable for salinity measurements. Since the salinity variations change at the time scale of hours, a running average can be performed to increase the accuracy of the measurements. Recent results of this work will be presented here. - Highlights: Black-Right-Pointing-Pointer Multiphase flow gas-fraction and flow regime measurements by multi gamma ray beams. Black-Right-Pointing-Pointer High-speed gamma ray tomograph as reference for the flow

  2. Tomographic multiphase flow measurement

    International Nuclear Information System (INIS)

    Sætre, C.; Johansen, G.A.; Tjugum, S.A.

    2012-01-01

    Measurement of multiphase flow of gas, oil and water is not at all trivial and in spite of considerable achievements over the past two decades, important challenges remain (). These are related to reducing measurement uncertainties arising from variations in the flow regime, improving long term stability and developing new means for calibration, adjustment and verification of the multiphase flow meters. This work focuses on the first two issues using multi gamma beam (MGB) measurements for identification of the type of flow regime. Further gamma ray tomographic measurements are used for reference of the gas/liquid distribution. For the MGB method one Am-241 source with principal emission at 59.5 keV is used because this relatively low energy enables efficient collimation and thereby shaping of the beams, as well as compact detectors. One detector is placed diametrically opposite the source whereas the second is positioned to the side so that this beam is close to the pipe wall. The principle is then straight forward to compare the measured intensities of these detectors and through that identify the flow pattern, i.e. the instantaneous cross-sectional gas-liquid distribution. The measurement setup also includes Compton scattering measurements, which can provide information about the changes in the water salinity for flow segments with high water liquid ratio and low gas fractions. By measuring the transmitted intensity in short time slots (<100ms), rapid regime variations are revealed. From this we can select the time sections suitable for salinity measurements. Since the salinity variations change at the time scale of hours, a running average can be performed to increase the accuracy of the measurements. Recent results of this work will be presented here. - Highlights: ► Multiphase flow gas-fraction and flow regime measurements by multi gamma ray beams. ► High-speed gamma ray tomograph as reference for the flow pattern and gas fraction. ► Dual modality

  3. Numerical investigation of aerodynamic flow actuation produced by surface plasma actuator on 2D oscillating airfoil

    Directory of Open Access Journals (Sweden)

    Minh Khang Phan

    2016-08-01

    Full Text Available Numerical simulation of unsteady flow control over an oscillating NACA0012 airfoil is investigated. Flow actuation of a turbulent flow over the airfoil is provided by low current DC surface glow discharge plasma actuator which is analytically modeled as an ion pressure force produced in the cathode sheath region. The modeled plasma actuator has an induced pressure force of about 2 kPa under a typical experiment condition and is placed on the airfoil surface at 0% chord length and/or at 10% chord length. The plasma actuator at deep-stall angles (from 5° to 25° is able to slightly delay a dynamic stall and to weaken a pressure fluctuation in down-stroke motion. As a result, the wake region is reduced. The actuation effect varies with different plasma pulse frequencies, actuator locations and reduced frequencies. A lift coefficient can increase up to 70% by a selective operation of the plasma actuator with various plasma frequencies and locations as the angle of attack changes. Active flow control which is a key advantageous feature of the plasma actuator reveals that a dynamic stall phenomenon can be controlled by the surface plasma actuator with less power consumption if a careful control scheme of the plasma actuator is employed with the optimized plasma pulse frequency and actuator location corresponding to a dynamic change in reduced frequency.

  4. Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Sandahl Christiansen, J; Christensen, C K; Hermansen, K

    1986-01-01

    Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8....... No changes in blood pressure or urinary albumin excretion rates took place in either group. The reduction in plasma protein and in plasma growth hormone concentration were similar in the two groups. No change was seen in plasma arginine vasopressin concentration. There was no difference in the qualitative...

  5. Active control of massively separated high-speed/base flows with electric arc plasma actuators

    Science.gov (United States)

    DeBlauw, Bradley G.

    bimodal recirculation region behavior was found in the no-control flow field that the plasma actuators could force. The flow field and turbulence statistics in each mode were substantially different. Through analysis of past no-control base pressure measurements, it is believed that the bimodal behavior fluctuates at a characteristic frequency between 0.4 and 0.5 Hz [StD = [special character omitted](5x10-5)]. The flat time-averaged base pressure distribution is due to the superposition of a normally non-flat instantaneous base pressure distribution. Also, the standard deviation of the base pressure measurements is reduced when in one recirculation region mode as compared to when it is fluctuating between recirculation region modes.

  6. Plasma fluctuation measurements in tokamaks using beam-plasma interactions (abstract)

    International Nuclear Information System (INIS)

    Fonck, R.J.; Duperrex, P.A.; Paul, S.F.

    1990-01-01

    High-frequency observations of light emitted from the interactions between plasma ions and injected neutral beam atoms allow the measurement of moderate-wavelength fluctuations in plasma and impurity ion densities. To detect turbulence in the local plasma ion density, the collisionally excited fluorescence from a neutral beam is measured either separately at several spatial points or with a multichannel imaging detector. Similarly, the role of impurity ion density fluctuations is measured using charge exchange recombination excited transitions emitted by the ion species of interest. This technique can access the relatively unexplored region of long-wavelength plasma turbulence with k perpendicular ρ i much-lt 1, and hence complements measurements from scattering experiments. Optimization of neutral beam geometry and optical sightlines can result in very good localization and resolution (Δx≤1 cm) in the hot plasma core region. The detectable fluctuation level is determined by photon statistics, atomic excitation processes, and beam stability, but can be as low as 0.2% in a 100 kHz bandwidth over the 0--1 MHz frequency range. The choices of beam species (e.g., H 0 , He 0 , etc.), observed transition (e.g., H α , L α , He I singlet or triplet transitions, C VI Δn=1, etc.) are dictated by experiment-specific factors such as optical access, flexibility of beam operation, plasma conditions, and detailed experimental goals. Initial tests on the PBX-M tokamak using the H α emissions from a heating neutral beam show low-frequency turbulence in the edge plasma region

  7. Density and velocity measurements of a sheath plasma from MPD thruster

    Energy Technology Data Exchange (ETDEWEB)

    Ko, J.J.; Cho, T.S.; Choi, M.C.; Choi, E.H.; Cho, G.S.; Uhm, H.S.

    1999-07-01

    Magnetoplasma is the plasma that the electron and ion orbits are strongly confined by intense magnetic field. Recently, magnetoplasma dynamics (MPD) has been investigated in connection with applications to the rocket thruster in USA, Germany, etc. It can be widely applicable, including modification of satellite position and propulsion of the interplanetary space shuttle. A travel for a long distance journey is possible because a little amount of neutral gases is needed for the plasma source. Besides, this will provide a pollution free engine for future generations. MPD thruster is not a chemical engine. The authors have built a Mather type MPD thruster, which has 1 kV max charging, 10 kA max current flows, and has about 1 ms characteristic operation time. The Paschen curve of this thruster is measured and its minimum breakdown voltage occurs in the pressure range of 0.1 to 1 Torr. Langmuir and double probes are fabricated to diagnose the sheath plasma from the thruster. The temperature and density are calculated to be 2.5 eV and 10{sup 15} cm {sup {minus}3}, respectively, from the probe data. Making use of photo diode, an optical probe is fabricated to measure propagation velocity of the sheath plasma. The sheath plasma from the MPD thruster in the experiment propagates with velocity of 1 cm/{micro}s.

  8. Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

    International Nuclear Information System (INIS)

    Walker, R.C.; Villante, U.; Lazarus, A.J.

    1975-01-01

    We present the results of an extensive analysis of plasma and magnetic field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 R/sub E/ downstream from earth. The principal observations are (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma

  9. Pioneer 7 observations of plasma flow and field reversal regions in the distant geomagnetic tail

    Science.gov (United States)

    Walker, R. C.; Lazarus, A. J.; Villante, U.

    1975-01-01

    The present paper gives the results of an extensive analysis of plasma and magnetic-field data from Pioneer 7 taken in the geomagnetic tail approximately 1000 earth radii downstream from earth. The principal observations are: (1) measurable fluxes of protons in the tail, flowing away from earth, sometimes with a double-peaked velocity distribution; (2) field reversal regions in which the field changes from radial to antiradial by a vector rotation in the north-south plane; and (3) general characteristics of the tail similar to those observed near earth with good correlation between taillike magnetic fields and plasma.

  10. Three electrode atmospheric pressure plasma jet in helium flow

    Science.gov (United States)

    Maletic, Dejan; Puac, Nevena; Malovic, Gordana; Petrovic, Zoran Lj.

    2015-09-01

    Plasma jets are widely used in various types of applications and lately more and more in the field of plasma medicine. However, it is not only their applicability that distinguishes them from other atmospheric plasma sources, but also the behavior of the plasma. It was shown that plasma plume is not continuous, but discrete set of plasma packages. Here we present iCCD images and current voltage characteristics of a three electrode plasma jet. Our plasma jet has a simple design with body made of glass tube and two transparent electrodes wrapped around it. The additional third metal tip electrode was positioned at 10 and 25 mm in front of the jet nozzle and connected to the same potential as the powered electrode. Power transmitted to the plasma was from 0.5 W to 4.0 W and the helium flow rate was kept constant at 4 slm. For the 10 mm configuration plasma is ignited on the metal tip in the whole period of the excitation signal and in the positive half cycle plasma ``bullet'' is propagating beyond the metal tip. In contrast to that, for the 25 mm configuration at the tip electrode plasma can be seen only in the minimum and maximum of the excitation signal, and there is no plasma ``bullet'' formation. This research has been supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, under projects ON171037 and III41011.

  11. Fast Plasma Potential Measurements Using an Emissive Probe

    Science.gov (United States)

    Ready, Amanda; Clark, Michael; Endrizzi, Douglass; Forest, Cary; Peterson, Ethan

    2017-10-01

    A heated emissive probe was developed for making direct plasma potential (Vp) measurements in rapidly fluctuating plasmas. Previous experiments on the Big Red Ball (BRB) were hindered by sudden potential drops, making Langmuir measurements of the plasma potential difficult. DC heating of a tungsten filament to emission allowed for fast (4 MHz) floating potential measurements that closely matched Vp. Two BRB experiments currently use the emissive probe. The investigation of unmagnetized, collisionless shocks used plasma potential measurements to study the sub-structure of strong plasma shocks. A separate investigation of emulated magnetospheres in laboratory plasmas used the plasma potential to map the equilibria and instabilities in the electric field of such structures. Results showing electric field measurements and comparison with cold Langmuir measurements will be presented. Future plans for probe modifications and applications to other experiments on the BRB will also be shown.

  12. Characteristics of steady-state plasma flow in the tokamak limiter scrape-off layer

    International Nuclear Information System (INIS)

    Petrov, V.G.

    1984-01-01

    Steady state plasma flow in the scrape-off layer of a toroidal limiter is discussed. The force balance along the torus minor radius is taken into account, from which follows that the plasma pressure gradient is balanced by the ponderomotive force (1/c) j-vectorxB-vector, which arises in the presence of a current density component perpendicular to the magnetic field. The limiter has an important effect on the electric current flow in the scrape-off layer. It is shown that the electric potential and plasma density values differ from one side of the limiter to the other; this leads to plasma drift along the minor radius. The characteristic length of change in the plasma density is found to be of the order of the ion cyclotron radius calculated for a poloidal magnetic field. (author)

  13. A continuous flow micro filtration device for plasma/blood separation using submicron vertical pillar gap structures

    International Nuclear Information System (INIS)

    Kang, Tae Goo; Ji, Hongmiao; Lim, Pei Yi; Chen, Yu; Yoon, Yong-Jin

    2014-01-01

    This work demonstrates a continuous flow plasma/blood separator using a vertical submicron pillar gap structure. The working principle of the proposed separator is based on size exclusion of cells through cross-flow filtration, in which only plasma is allowed to pass through submicron vertical pillars located tangential to the main flow path of the blood sample. The maximum filtration efficiency of 99.9% was recorded with a plasma collection rate of 0.67 µl min −1 for an input blood flow rate of 12.5 µl min −1 . The hemolysis phenomenon was observed for an input blood flow rate above 30 µl min −1 . Based on the experimental results, we can conclude that the proposed device shows potential for the application of on-chip plasma/blood separation as a part of integrated point-of-care (POC) diagnostics systems. (technical note)

  14. Radio Frequency Enhanced Plasma Potential and Flows in the Scrap-Off Layer of an Active Antenna

    Science.gov (United States)

    Martin, Michael John

    Ion cyclotron resonance heating (ICRH) systems are critical components of current and future tokamak experiments aimed at producing nuclear fusion energy. During ICRH a host of deleterious effects occur, including increased heat flux to plasma facing components and modification of launched wave power. A suspected root cause of these effects is the radio frequency (RF) rectification of the plasma potential. Interest in the antenna scrape-off layer (SOL) region has drawn increasing interest, as it is recognized that mitigating these effects is necessary to achieving fusion power. This dissertation investigates the RF rectification of the plasma potential and the resulting cross-field flows that form due to an active RF antenna. The experiment is performed in the Large Plasma Device (LAPD) utilizing a fast wave antenna and RF amplifier system developed for these studies. The RF system is capable of 150 kW output power for a 1 ms pulse that is repeated at the 1 Hz repetition rate of the LAPD plasma discharge. Upon application of the RF pulse to the antenna, the DC plasma potential, measured with an emissive probe, dramatically increases in certain spatial locations by a factor greater than 10 Te. The largest plasma potentials are observed at locations magnetically connected to the top and bottom of the antenna, and they exist only in the private SOL created between the antenna and a limiter placed 3.6 m away along the LAPD axis. The DC rectified potentials scale linearly with the antenna current over a factor of 12x in the applied current. These DC potentials increase plasma materials interactions (PMI), resulting in the sputtering of antenna materials whose presence is detected in the bulk plasma by the coatings that develop on probe diagnostics. The DC rectified potentials persist in the plasma long after the RF current in the antenna has rung down on the same time scales as the change in the density. At the top and bottom of the antenna are circular flows, often

  15. 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

  16. Merging of magnetic fields with field-aligned plasma flow components

    International Nuclear Information System (INIS)

    Mitchell, H.G. Jr.; Kan, J.R.

    1978-01-01

    The Sonnerup merging model for an incompressible plasma is extended to allow a flow component along the field lines in the inflow regions. Solutions are found to exist as long as the difference between the quantities B. V for the two inflow regions does not exceed a critical magnitude dependent on the inflow field magnitudes and plasma densities. All such solutions satisfy Vasyliunas' definition of merging, but some classes of solution have radically altered geometries, i.e. geometries in which the inflow regions are much smaller than the outflow regions. The necessary but not sufficient condition for these unusual geometries is that the field-aligned flow component in at least one inflow region be super-Alfvenic. A solution for the case of a vacuum field in one inflow region is obtained in which any flow velocity is allowed in the non-vacuum inflow region, although super-Alfvenic flow can still result in an unusual geometry. For symmetric configurations, the usual geometry, that of Petschek and Sonnerup, is retained as long as both field-aligned flow components in the inflow regions are less than twice the inflow Alfven speed. For the case of a vacuum field on one side and fields approximating the boundary between the solar wind and the earth's dayside magnetosphere, the usual geometry is retained for flow less than about 2.5 times the local Alfven speed. (author)

  17. Radiation yield from SHIVA Star plasma flow switch driven fast liner implosions

    International Nuclear Information System (INIS)

    Degnan, J.H.; Baker, W.L.; Beason, J.D.

    1987-01-01

    A 2.5 Terawatt 0.5 MJ isotropic equivalent radiation yield was obtained in a SHIVA Star plasma flow switch driven fast liner implosion. The 1313 μF 80 kV discharge delivered 13 MA to a coaxial vacuum inductive store with a plasma armature. Over 9.4 MA current was plasma flow switched to the implosion load (>90% of the gun muzzle current at that time). The load wa a 5 cm radius, 2 cm tall, 200 μg/cm/sup 2/ aluminum plated Formvar cylindrical foil. The radiation pulse was measured with an array of seven X-ray diodes (XRDs). The XRDs all had aluminum photocathodes, a variety of filters and nickel mesh to reduce the incident X-ray photon flux to avoid Child-Langmuir saturation. The filters were chosen so that the authors had seven different diode response functions covering the energy range from 15 eV to about 3 keV. The filters were mounted remote (about 30 cm) from the XRDs. The anode mesh served as part of the mesh array. The distance between meshes was greater than 10 cm. Each XRD had a 5 cm diameter cathode with an aperture limited to a 2 cm diameter. The XRD anode-cathode gap was 1 cm and the bias was 5 kV. The theoretical Child-Langmuir saturation signal was 125 V with 50 Ω termination. The maximum observed signal was 75 V

  18. Evaluation of flow hood measurements for residential register flows; TOPICAL

    International Nuclear Information System (INIS)

    Walker, I.S.; Wray, C.P.; Dickerhoff, D.J.; Sherman, M.H.

    2001-01-01

    Flow measurement at residential registers using flow hoods is becoming more common. These measurements are used to determine if the HVAC system is providing adequate comfort, appropriate flow over heat exchangers and in estimates of system energy losses. These HVAC system performance metrics are determined by using register measurements to find out if individual rooms are getting the correct airflow, and in estimates of total air handler flow and duct air leakage. The work discussed in this paper shows that commercially available flow hoods are poor at measuring flows in residential systems. There is also evidence in this and other studies that flow hoods can have significant errors even when used on the non-residential systems they were originally developed for. The measurement uncertainties arise from poor calibrations and the sensitivity of exiting flow hoods to non-uniformity of flows entering the device. The errors are usually large-on the order of 20% of measured flow, which is unacceptably high for most applications. Active flow hoods that have flow measurement devices that are insensitive to the entering airflow pattern were found to be clearly superior to commercially available flow hoods. In addition, it is clear that current calibration procedures for flow hoods may not take into account any field application problems and a new flow hood measurement standard should be developed to address this issue

  19. Experimental study of the efficiency of transformation of the dense plasma hypersonic flow kinetic energy into a radiation

    International Nuclear Information System (INIS)

    Kamrukov, A.S.; Kozlov, N.P.; Myshelov, E.P.; Protasov, Yu.S.

    1981-01-01

    Analysis of physical specific features of radiator where plasma heating is performed with tbermalization of directed kinetic energy of dense plasma flows accelerated electrodynamically up to hypersonic velocities during its shock deceleration, is given. It is shown that the plasma heating method considered has a number of principle advantages as compared with methods most disseminated now for generation of dense intensively radiating plasma (current heating exploding method) and suggests new possibilities for construction of selective high brightness radiat.ion sources of ultraviolet and far vacuum ultraviolet ranges of spectrum. Radiation gas dynamic processes of hypersonic plasma flow deceleration formed with magnetoplasma compressors have been experimentally investigated on their interaction with condenced matters in vacuum and basic thermodynamic parameters of shock compressed plasma have been determined. It is shown that the conversion process of kinetic energy of high-velocity plasma flows to radiation is accomplished at very high efficiency-integral luminescence of shock compressed plasma can reach approximately 90% of initial kinetic energy of flow [ru

  20. Reynolds stress and shear flow generation

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Naulin, V.

    2001-01-01

    The so-called Reynolds stress may give a measure of the self-consistent flow generation in turbulent fluids and plasmas by the small-scale turbulent fluctuations. A measurement of the Reynolds stress can thus help to predict flows, e.g. shear flows in plasmas. This may assist the understanding...... of improved confinement scenarios such as H-mode confinement regimes. However, the determination of the Reynolds stress requires measurements of the plasma potential, a task that is difficult in general and nearly impossible in hot plasmas in large devices. In this work we investigate an alternative method......, based on density measurements, to estimate the Reynolds stress, and demonstrate the validity range of this quantity, which we term the pseudo-Reynolds stress. The advantage of such a quantity is that accurate measurements of density fluctuations are much easier to obtain experimentally. Prior...

  1. Dynamic and Stagnating Plasma Flow Leading to Magnetic-Flux-Tube Collimation

    International Nuclear Information System (INIS)

    You, S.; Yun, G.S.; Bellan, P.M.

    2005-01-01

    Highly collimated, plasma-filled magnetic-flux tubes are frequently observed on galactic, stellar, and laboratory scales. We propose that a single, universal magnetohydrodynamic pumping process explains why such collimated, plasma-filled magnetic-flux tubes are ubiquitous. Experimental evidence from carefully diagnosed laboratory simulations of astrophysical jets confirms this assertion and is reported here. The magnetohydrodynamic process pumps plasma into a magnetic-flux tube and the stagnation of the resulting flow causes this flux tube to become collimated

  2. Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

    Energy Technology Data Exchange (ETDEWEB)

    Swadling, G. F.; Lebedev, S. V.; Burdiak, G.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Hall, G. N.; Suzuki-Vidal, F.; Bland, S. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom); Harvey-Thompson, A. J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1193 (United States); Rozmus, W. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Yuan, J. [Key Laboratory of Pulsed Power, Institute of Fluid Physics, CAE, Mianyang 621900 (China)

    2015-07-15

    An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the “precursor” plasma near the axis of the array over the period 100–140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.

  3. Radiotracer techniques for measuring fluid flow and calibrating flow meters

    International Nuclear Information System (INIS)

    Cooper, E.L.

    1987-08-01

    Radiotracer techniques can be used to measure accurately both gas and liquid flow rates under operating conditions in a wide range of flow systems. They are ideally suited for calibrating flow meters as well as for measuring unmetered flows in industrial plants. Applications of these techniques range from measuring the flows of fuels and process fluids for energy and mass balance studies to measuring the flows of liquid and airborne effluents for pollution control. This report describes the various radiotracer techniques which can be used to measure fluid flows. The range of application and inherent accuracy of each technique is discussed

  4. Quick-fire: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

    1985-01-01

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion. Experiments have been conducted using the SHIVA STAR capacitor bank operating at 6 MJ stored energy in which performance has been monitored by electrical diagnostics, magnetic probes, and axial and radial viewing high speed visible and X-Ray photographs to assess the performance of the coaxial run and coaxial to radial transition. Time and spectrally resolved X-Ray diagnostics are used to assess implosion quality and performance and results are compared to kinematic and MHD models

  5. Monoexponential analysis of plasma disappearance of 99mTc-DTPA and 131I-iodohippurate: A reliable method for measuring changes of renal function

    International Nuclear Information System (INIS)

    Clifton, G.G.; Anderson, C.; McMahon, G.; Vargas, R.; Wallin, J.D.

    1989-01-01

    Glomerular filtration rate and effective renal plasma flow were measured in 170 subjects using monoexponential analysis of plasma disappearance curves for 99m Tc-DTPA and 131 I-iodohippurate after single injection. In the current study population, glomerular filtration rate and effective renal plasma flow decreased with increasing age, were less in females than in males, and were less in hypertensives than in normotensives. Differences in glomerular filtration rate according to age and sex in the current study were similar to those reported using traditional creatinine clearance methodology. Monoexponential treatment of plasma isotope disappearance gave reproducible values for both glomerular filtration rate and effective renal plasma flow when measured either during the day or on a daily basis. Intraindividual coefficient of variation was less than 10% for both 99m Tc-DTPA and 131 I-iodohippurate clearances derived from monoexponential analysis. These results demonstrate that monoexponential analysis of plasma disappearance curves for 99m Tc-DTPA and 131 I-iodohippurate after a single injection is a useful method for evaluating changes in renal hemodynamics either during chronic drug therapy or acutely after single dose administration

  6. Optical Measurements in Non-Equilibrium Plasmas and Flows

    Science.gov (United States)

    2009-09-01

    of the polarizability , , of the medium and the time-varying incident electric field ,E(t). p(t) E(t)  (14) Figure 2 Single...162 14 - 7 The polarizability is customarily expanded with respect to the vibrational normal coordinates (or “normal modes”), Q, of the molecule...spectrum, obtained from an argon glow discharge plasma at 50 mbar [36], is shown on the right side of Fig. 7. The inferred temperature is 479 ± 13 K

  7. Surface treatment by the ion flow from electron beam generated plasma in the forevacuum pressure range

    Directory of Open Access Journals (Sweden)

    Klimov Aleksandr

    2018-01-01

    Full Text Available The paper presents research results of peculiarities of gas ion flows usage and their generation from large plasma formation (>50 sq.cm obtained by electron beam ionization of gas in the forevacuum pressure range. An upgraded source was used for electron beam generation, which allowed obtaining ribbon electron beam with no transmitting magnetic field. Absence of magnetic field in the area of ion flow formation enables to obtain directed ion flows without distorting their trajectories. In this case, independent control of current and ion energy is possible. The influence of electron beam parameters on the parameters of beam plasma and ion flow – current energy and density – was determined. The results of alumina ceramics treatment with a beam plasma ions flow are given.

  8. BRIEF COMMUNICATION: On the drift kinetic equation driven by plasma flows

    Science.gov (United States)

    Shaing, K. C.

    2010-07-01

    A drift kinetic equation that is driven by plasma flows has previously been derived by Shaing and Spong 1990 (Phys. Fluids B 2 1190). The terms that are driven by particle speed that is parallel to the magnetic field B have been neglected. Here, such terms are discussed to examine their importance to the equation and to show that these terms do not contribute to the calculations of plasma viscosity in large aspect ratio toroidal plasmas, e.g. tokamaks and stellarators.

  9. The Influence of Relative Humidity on Dielectric Barrier Discharge Plasma Flow Control Actuator Performance

    Science.gov (United States)

    Wicks, M.; Thomas, F. O.; Corke, T. C.; Patel, M.

    2012-11-01

    Dielectric barrier discharge (DBD) plasma actuators possess numerous advantages for flow control applications and have been the focus of several previous studies. Most work has been performed in relatively pristine laboratory settings. In actual flow control applications, however, it is essential to assess the impact of various environmental influences on actuator performance. As a first effort toward assessing a broad range of environmental effects on DBD actuator performance, the influence of relative humidity (RH) is considered. Actuator performance is quantified by force balance measurements of reactive thrust while RH is systematically varied via an ultrasonic humidifier. The DBD plasma actuator assembly, force balance, and ultrasonic humidifier are all contained inside a large, closed test chamber instrumented with RH and temperature sensors in order to accurately estimate the average RH at the actuator. Measurements of DBD actuator thrust as a function of RH for several different applied voltage regimes and dielectric materials and thicknesses are presented. Based on these results, several important design recommendations are made. This work was supported by Innovative Technology Applications Company (ITAC), LLC under a Small Business Innovation Research (SBIR) Phase II Contract No. N00014-11-C-0267 issued by the U.S. Department of the Navy.

  10. Radiation accompanied by self absorption in nonequilibrium argon plasma flow in a circular tube

    International Nuclear Information System (INIS)

    Shirai, Hiroyuki; Tabei, Katsuine; Koaizawa, Hisashi.

    1983-01-01

    In high temperature, nonequilibrium plasma flow, generally strong radiation arises, but the radiation phenomena are complicated by the thermo-chemical nonequilibrium of gas and the self absorption in light path, accordingly it is important to correctly understand and estimate their effects. In this research, for the radiation from the argon afterglow plasma flow with large nonequilibrium property in a circular tube, the experimental and theoretical studies were carried out taking the self absorption in consideration. Experimentally, the absolute intensity distribution of the radiated spectrum lines was measured from outside of the tube, and converted to the true radial distribution of atom number density at excited level using the mathematical conversion theory for the radiation accompanied by absorption of Elder et al. Theoretically, the radial distributions of electron temperature, electron density and atom temperature measured in the tube were applied to the collision-radiation process model including self absorption, and the distribution of the atom number density at excited level was calculated. Fairly good agreement was obtained between both results, and it was found that the consideration of self absorption was important. The theory, the experiment, the numerical examination of a number of physical quantities and the simplification of the theory, and the results are reported. (Kako, I.)

  11. Noise control of subsonic cavity flows using plasma actuated receptive channels

    International Nuclear Information System (INIS)

    Gupta, Arnob Das; Roy, Subrata

    2014-01-01

    We introduce a passive receptive rectangular channel at the trailing edge of an open rectangular cavity to reduce the acoustic tones generated due to coherent shear layer impingement. The channel is numerically tested at Mach 0.3 using an unsteady three-dimensional large eddy simulation. Results show reduction in pressure fluctuations in the cavity due to which sound pressure levels are suppressed. Two linear dielectric barrier discharge plasma actuators are placed inside the channel to enhance the flow through it. Specifically, acoustic suppression of 7 dB was obtained for Mach 0.3 flow with the plasma actuated channel. Also, the drag coefficient for the cavity reduced by over three folds for the channel and over eight folds for the plasma actuated channel. Such a channel can be useful in noise and drag reduction for various applications, including weapons bay, landing gear and branched piping systems. (fast track communication)

  12. Numerical study on the two-dimensional flows of plasma and ionizing gas using trial particles

    International Nuclear Information System (INIS)

    Brushlinskij, K.V.; Kozlov, A.N.; Morozov, A.I.

    1985-01-01

    Two-dimensional flows of plasma and ionized αs in a channel between two coaxial electrodes are considered in the MHD-model with account of Hall effect. Stationary solutions of the problem on the flow are obtained either analytically in approximation of a ''smooth'' channel - for ideal conducting plasma, or numerically using the methos of establishment - in the ge-neral case of finite conductivity. A method of further numerical analysis of some peculiarities of flow is suggested in the paper. It is based on studying dynamics of single ''test'' particles in fields of the main MHD plasma flow. Trajectory of the test ion is calculated with account for interaction forces with earlier determined electromagentic field and friction responsible for Coulomb collisions with particles of the background flow. The calculations display trajectories of test particles with different masses, initial positions and initial rates. They are shown to be dose to current lines of background medium in plasma of finite conductivity, that testified to the virtue of effectiveness of the MHD-model. In case of ideal conductivity trajectories of test and background particles can noticeably differ from one another. Stabilization effects of motion of particles accidentally knocked out from the flow and separation of pariticles of different mass by electromao.netic forces are considered

  13. Plasma flow in a curved magnetic field

    International Nuclear Information System (INIS)

    Lindberg, L.

    1977-09-01

    A beam of collisionless plasma is injected along a longitudinal magnetic field into a region of curved magnetic field. Two unpredicted phenomena are observed: The beam becomes deflected in the direction opposite to that in which the field is curved, and it contracts to a flat slab in the plane of curvature of the magnetic field. The phenomenon is of a general character and can be expected to occur in a very wide range of densities. The lower density limit is set by the condition for self-polarization, nm sub(i)/epsilon 0 B 2 >> 1 or, which is equivalent, c 2 /v 2 sub(A) >> 1, where c is the velocity of light, and v sup(A) the Alfven velocity. The upper limit is presumably set by the requirement ωsub(e)tau(e) >> 1. The phenomenon is likely to be of importance e.g. for injection of plasma into magnetic bottles and in space and solar physics. The paper illustrates the comlexity of plasma flow phenomena and the importance of close contact between experimental and theoretical work. (author)

  14. The laser, measuring instrument for plasmas

    International Nuclear Information System (INIS)

    Anderegg, F.; Behn, R.; Paris, P.J.; Salito, S.A.; Siegrist, M.R.; Weisen, H.

    1988-06-01

    There are several different and in general complementary methods for the investigation of plasmas. All of them have different characteristics and properties covering a large spectrum of physical measuring techniques. Electromagnetic waves serving as 'thermometers' permit to detect the global behaviour of the plasma as well as that of the particles composing it. One of the advantages of these introspective methods is that it brings information on temporary and local conditions of the domain being interrogated. With the development of micro-wave sources and lasers after the war the principal tools of this type of plasma diagnostics are now available. In this paper the emphasis is on the lasers which are different according to the type of measurement. Their versatility in measuring plasma parameters is largely acknowledged. We illustrate the potential of measuring methods by lasers by means of the research work done at two experimental installations of CRPP. (author) 21 figs., 8 refs

  15. Neutron measurement techniques for tokamak plasmas

    International Nuclear Information System (INIS)

    Jarvis, O.N.

    1994-01-01

    The present article reviews the neutron measurement techniques that are currently being applied to the study of tokamak plasmas. The range of neutron energies of primary interest is limited to narrow bands around 2.5 and 14 MeV, and the variety of measurements that can be made for plasma diagnostic purposes is also restricted. To characterize the plasma as a neutron source, it is necessary only to measure the total neutron emission, the relative neutron emissivity as a function of position throughout the plasma, and the energy spectra of the emitted neutrons. In principle, such measurements might be expected to be relatively easy. That this is not the case is, in part, attributable to practical problems of accessibility to a harsh environment but is mostly a consequence of the time-scale on which the measurements have to be made and of the wide range of neutron emission intensities that have to be covered: for tokamak studies, the time-scale is of the order of 1 to 100 ms and the neutron intensity ranges from 10 12 to 10 19 s -1 . (author)

  16. Effect of PTA on blood pressure, renal plasma flow and renal venous renin activity in renovascular hypertension

    International Nuclear Information System (INIS)

    Arlart, I.P.; Dewitz, H. von; Rosenthal, J.

    1983-01-01

    Percutaneous transluminal angioplasty (PTA) is more and more accepted for interventional management of renal artery stenosis in hypertensive patients. This study was carried out to assess the behaviour of arterial blood-pressure, renal plasma flow and renal venous rening activity in renovascular hypertension following catheter dilatation. Using the data the possibility is calculated to predict the effect of PTA on blood pressure preinterventionally. The results demonstrate that a successful employment of PTA depends on a normal contralateral renal plasma flow and a normalization of plasma flow of the poststenotic kidney. Determination of plasma renin activity is only of restricted value. (orig.)

  17. Plasma assisted measurements of alkali metal concentrations in pressurized combustion processes

    International Nuclear Information System (INIS)

    Hernberg, R.; Haeyrinen, V.

    1995-01-01

    The plasma assisted method for continuous measurement of alkali metal concentrations in product gas flows of pressurized energy processes will be tested and applied at the 1.6 MW PFBC/G facility at Delft University of Technology in the Netherlands. Measurements will be performed during 1995 and 1996 at different stages of the research programme. The results are expected to give information about the influence of different process conditions on the generation of alkali metal vapours, the comparison of different methods for alkali measurement and the specific performance of our system. The project belongs to the Joule II extension program under contract JOU2-CT93-0431. (author)

  18. Cluster view of the plasma sheet boundary layer and bursty bulk flow connection

    Directory of Open Access Journals (Sweden)

    O. W. Lennartsson

    2009-04-01

    Full Text Available The high-latitude boundaries of the plasma sheet (PSBL are dynamic latitude zones of recurring and transient (minutes to tens of minutes earthward and magnetic field-aligned bursts of plasma, each being more or less confined in longitude as well, whose ionic component is dominated by protons with flux, energies and density that are consistent with a central plasma sheet (CPS source at varying distance (varying rates of energy time dispersion, sometimes as close as the ~19 RE Cluster apogees, or closer still. The arguably most plausible source consists of so called "bursty bulk flows" (BBFs, i.e. proton bulk flow events with large, positive and bursty GSE vx. Known mainly from CPS observations made at GSE x>−30 RE, the BBF type events probably take place much further downtail as well. What makes the BBFs an especially plausible source are (1 their earthward bulk flow, which helps explain the lack of distinctive latitudinal PSBL energy dispersion, and (2 their association with a transient strong increase of the local tail Bz component ("local dipolarization". The enhanced Bz provides intermittent access to higher latitudes for the CPS plasma, resulting in local density reductions in the tail midplane, as illustrated here by proton data from the Cluster CIS CODIF instruments. Another sign of kinship between the PSBL bursts and the BBFs is their similar spatial fine structure. The PSBL bursts have prominent filaments aligned along the magnetic field with transverse flux gradients that are often characterized by local ~10 keV proton gyroradii scale size (or even smaller, as evidenced by Cluster measurements. The same kind of fine structure is also found during Cluster near-apogee traversals of the tail midplane, as illustrated here and implied by recently published statistics on BBFs obtained with Cluster multipoint observations at varying satellite separations. Altogether, the Cluster observations described here mesh rather well with theories

  19. Spontaneous electromagnetic emission from a strongly localized plasma flow.

    Science.gov (United States)

    Tejero, E M; Amatucci, W E; Ganguli, G; Cothran, C D; Crabtree, C; Thomas, E

    2011-05-06

    Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed.

  20. Plasma-based actuators for turbulent boundary layer control in transonic flow

    Science.gov (United States)

    Budovsky, A. D.; Polivanov, P. A.; Vishnyakov, O. I.; Sidorenko, A. A.

    2017-10-01

    The study is devoted to development of methods for active control of flow structure typical for the aircraft wings in transonic flow with turbulent boundary layer. The control strategy accepted in the study was based on using of the effects of plasma discharges interaction with miniature geometrical obstacles of various shapes. The conceptions were studied computationally using 3D RANS, URANS approaches. The results of the computations have shown that energy deposition can significantly change the flow pattern over the obstacles increasing their influence on the flow in boundary layer region. Namely, one of the most interesting and promising data were obtained for actuators basing on combination of vertical wedge with asymmetrical plasma discharge. The wedge considered is aligned with the local streamlines and protruding in the flow by 0.4-0.8 of local boundary layer thickness. The actuator produces negligible distortion of the flow at the absence of energy deposition. Energy deposition along the one side of the wedge results in longitudinal vortex formation in the wake of the actuator providing momentum exchange in the boundary layer. The actuator was manufactured and tested in wind tunnel experiments at Mach number 1.5 using the model of flat plate. The experimental data obtained by PIV proved the availability of the actuator.

  1. Ion flow ripples in the Earth's plasma sheet

    Science.gov (United States)

    De Spiegeleer, Alexandre; Hamrin, Maria; Pitkänen, Timo; Norqvist, Patrik; Mann, Ingrid

    2016-04-01

    For a long time, magnetotail flows were considered rather smooth and laminar, and primarily dominated by a simple convection flow pattern. However, in the early 90's, high speed bursty bulk flows (BBFs) were discovered and found to commonly perturb the underlying convection flows. In addition, there are other disturbances complicating the magnetotail flow pattern. Instabilities such as the Kelvin-Helmholz instability and the kink instability can cause different types of magnetic field oscillations, such as field line resonances. It is expected that ions will follow these oscillations if the typical time and length scales are larger than the gyroperiod and gyroradius of the ions. Though low-velocity sloshing and ripple disturbances of the average magnetotail convection flows have been observed, their connection with magnetic field oscillations is not fully understood. Furthermore, when studying BFFs, these "Ion Flow Ripples" (IFRs) are often neglected, dismissed as noise or can even erroneously be identified as BBFs. It is therefore of utter importance to find out and understand the role of IFRs in magnetotail dynamics. In a statistical investigation, we use several years of Cluster plasma sheet data to study the low-speed flows in the magnetotail. We investigate different types of IFRs, study their occurrence, and discuss their possible causes.

  2. Generation of sheared poloidal flows by electrostatic and magnetic Reynolds stress in the boundary plasma of HT-7 tokamak

    International Nuclear Information System (INIS)

    Xu, G.S.; Wan, B.N.; Li, J.

    2005-01-01

    The radial profiles of electrostatic and magnetic Reynolds stress (Maxwell stress) have been measured in the plasma boundary region of HT-7 tokamak. Experimental results show that the radial gradient of electrostatic Reynolds stress (ERS) changes sign across the last closed flux surface, and the neoclassical flow damping and the damping due to charge exchange processes are balanced by the radial gradient of ERS, which sustains the equilibrium sheared flow structure in a steady state. The contribution of magnetic Reynolds stress was found unimportant in a low β plasma. Detailed analyses indicate that the propagation properties of turbulence in radial and poloidal directions and the profiles of potential fluctuation level are responsible for the radial structure of ERS. (author)

  3. Flow characteristics of bounded self-organized dust vortex in a complex plasma

    Science.gov (United States)

    Laishram, Modhuchandra; Sharma, D.; Chattopdhyay, P. K.; Kaw, P. K.

    2018-01-01

    Dust clouds are often formed in many dusty plasma experiments, when micron size dust particles introduced in the plasma are confined by spatial non-uniformities of the potential. These formations show self-organized patterns like vortex or circulation flows. Steady-state equilibrium dynamics of such dust clouds is analyzed by 2D hydrodynamics for varying Reynolds number, Re, when the cloud is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in a dynamic equilibrium with an unbounded sheared plasma flow. The nonconservative forcing due to ion flow shear generates finite vorticity in the confined dust clouds. In the linear limit (Re ≪ 1), the collective flow is characterized by a single symmetric and elongated vortex with scales correlating with the driving field and those generated by friction with the boundaries. However in the high Re limit, (Re ≥ 1), the nonlinear inertial transport (u . ∇u) is effective and the vortex structure is characterized by an asymmetric equilibrium and emergence of a circular core region with uniform vorticity, over which the viscous stress is negligible. The core domain is surrounded by a virtual boundary of highly convective flow followed by thin shear layers filled with low-velocity co- and counter-rotating vortices, enabling the smooth matching with external boundary conditions. In linear regime, the effective boundary layer thickness is recovered to scale with the dust kinematic viscosity as Δr ≈ μ1/3 and is modified as Δr ≈ (μL∥/u)1/2 in the nonlinear regime through a critical kinematic viscosity μ∗ that signifies a structural bifurcation of the flow field solutions. The flow characteristics recovered are relevant to many microscopic biological processes at lower Re, as well as gigantic vortex flows such as Jovian great red spot and white ovals at higher Re.

  4. Determining tumor blood flow parameters from dynamic image measurements

    Science.gov (United States)

    Libertini, Jessica M.

    2008-11-01

    Many recent cancer treatments focus on preventing angiogenesis, the process by which a tumor promotes the growth of large and efficient capillary beds for the increased nourishment required to support the tumor's rapid growth[l]. To measure the efficacy of these treatments in a timely fashion, there is an interest in using data from dynamic sequences of contrast-enhanced medical imaging, such as MRI and CT, to measure blood flow parameters such as perfusion, permeability-surface-area product, and the relative volumes of the plasma and extracellular-extravascular space. Starting with a two compartment model presented by the radiology community[2], this work challenges the application of a simplification to this problem, which was originally developed to model capillary reuptake[3]. While the primary result of this work is the demonstration of the inaccuracy of this simplification, the remainder of the paper is dedicated to presenting alternative methods for calculating the perfusion and plasma volume coefficients. These methods are applied to model data sets based on real patient data, and preliminary results are presented.

  5. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Winterberg, F. [University of Nevada, Reno, Reno, Nevada (United States)

    2016-01-15

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  6. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Science.gov (United States)

    Winterberg, F.

    2016-01-01

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  7. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    International Nuclear Information System (INIS)

    Winterberg, F.

    2016-01-01

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable

  8. Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

    Science.gov (United States)

    Mason, Rod S; Mitchell, David J; Dickinson, Paul M

    2010-04-21

    Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical

  9. Flow control over a NACA 0012 airfoil using dielectric-barrier-discharge plasma actuator with a Gurney flap

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Li-Hao [Beijing University of Aeronautics and Astronautics, Fluid Mechanics Key Laboratory of Education Ministry, Beijing (China); University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); Jukes, Timothy N. [University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); AIST, Research Centre for New Fuels and Vehicle Technology, Tsukuba (Japan); Choi, Kwing-So [University of Nottingham, University Park, Faculty of Engineering, Nottingham (United Kingdom); Wang, Jin-Jun [Beijing University of Aeronautics and Astronautics, Fluid Mechanics Key Laboratory of Education Ministry, Beijing (China)

    2012-06-15

    Flow control study of a NACA 0012 airfoil with a Gurney flap was carried out in a wind tunnel, where it was demonstrated that a dielectric-barrier-discharge (DBD) plasma actuator attached to the flap could increase the lift further, but with a small drag penalty. Time-resolved PIV measurements of the near-wake region indicated that the plasma forcing shifted the wake downwards, reducing its recirculation length. Analysis of wake vortex dynamics suggested that the plasma actuator initially amplified the lower wake shear layer by adding momentum along the downstream surface of the Gurney flap. This enhanced mutual entrainment between the upper and lower wake vortices, leading to an increase in lift on the airfoil. (orig.)

  10. Interaction of Ambipolar Plasma Flow with Magnetic Islands in a Quasi-axisymmetric Stellarator

    International Nuclear Information System (INIS)

    Reiman, A.; Zarnstorff, M.; Mikkelsen, D.; Owen, L.; Mynick, H.; Hudson, S.; Monticello, D.

    2004-01-01

    A reference equilibrium for the U.S. National Compact Stellarator Experiment is predicted to be sufficiently close to quasi-symmetry to allow the plasma to flow in the toroidal direction with little viscous damping, yet to have sufficiently large deviations from quasi-symmetry that nonambipolarity significantly affects the physics of the shielding of resonant magnetic perturbations by plasma flow. The unperturbed velocity profile is modified by the presence of an ambipolar potential, which broadens the profile and improves the shielding near the plasma edge. In the presence of a resonant magnetic field perturbation, nonambipolar transport produces a radial current, and the resulting jxB force resists departures from the ambipolar velocity and enhances the shielding

  11. Interaction of ambipolar plasma flow with magnetic islands in a quasi-axisymmetric stellarator

    International Nuclear Information System (INIS)

    Reiman, A.; Zarnstorff, M.; Mikkelsen, D.; Mynick, H.; Hudson, S.; Monticello, D.; Owen, L.

    2005-01-01

    A reference equilibrium for the US National Compact Stellarator Experiment is predicted to be sufficiently close to quasi-symmetry to allow the plasma to flow in the toroidal direction with little viscous damping, yet to have sufficiently large deviations from quasi-symmetry that nonambipolarity significantly affects the physics of the shielding of resonant magnetic perturbations by plasma flow. The unperturbed velocity profile is modified by the presence of an ambipolar potential, which broadens the profile and improves the shielding near the plasma edge. In the presence of a resonant magnetic field perturbation, nonambipolar transport produces a radial current, and the resulting jxB force resists departures from the ambipolar velocity and enhances the shielding. (author)

  12. Pre-analytical and Analytical Variables Affecting the Measurement of Plasma-Derived Microparticle Tissue Factor Activity

    Science.gov (United States)

    Lee, RD; Barcel, DA; Williams, JC; Wang, JG; Boles, JC; Manly, DA; Key, NS; Mackman, N

    2011-01-01

    Introduction Elevated levels of tissue factor positive (TF+) microparticles (MPs) are observed in plasma from a variety of patients with an increased risk of thrombosis. We and others have described the measurement of TF activity in MPs isolated from plasma. The aim of this study was to investigate the effects of pre-analytical and analytical variables on TF activity of MPs isolated from blood of healthy volunteers treated ex vivo with or without bacterial lipopolysaccharide. Materials and Methods We evaluated the following parameters: use of different centrifugation speeds to isolate the MPs; comparison of TF activity of MPs isolated from platelet poor plasma versus platelet free plasma; effect of freeze/thaw on MP TF activity; and comparison of the MP TF activity assay with the measurement of TF protein by ELISA or flow cytometry. Results MPs prepared from platelet poor plasma by centrifugation at 20,000 × g or 100,000 × g for 15 minutes had similar levels of TF activity. However, significantly less TF activity was found in MPs isolated from platelet free plasma compared with platelet poor plasma. Interestingly, freeze/thawing of the plasma showed donor to donor variation in MP TF activity, with a moderate increase in some individuals. Conclusion TF+ MPs can be quantitatively isolated from platelet poor or platelet free plasma by centrifugation at 20,000 × g for 15 minutes. Measurement of MP TF activity in plasma can be used to detect a prothrombotic state in patients with various diseases. PMID:21737126

  13. Experimental study of collisionless interaction between superalfven mutually penetrating plasma flows

    International Nuclear Information System (INIS)

    Antonov, V.M.; Bashurin, V.P.; Golubev, A.I.; Zhmajlo, V.A.; Zakharov, Yu.P.; Orishich, A.M.; Ponomarenko, A.G.; Posukh, V.G.; Snytnikov, V.N.

    1985-01-01

    To develop new methods of magnetic-gaseous protection of the first wall of thermonuclear reactor with inertial confainment, the processes of collisionless interaction of laser plasma expanding cloud with magnetized background at high Mach-Alfven numbers (Msub(A)>=5) are investigated. Experimental results on laboratory simulation of interaction processes of superalfvenic plasma flow with the number of particles N 1 approximately equal to 10 18 in the background plasma n approximately equal to 3x10 13 cm sup(-3) are presented. In the presence of magnetic field, when Larmour's ionic radii of the cloud and background are compared with the scale R=(3N 1 z 1 /4πn)1/3, intensive pulsetransfer from the cloud to the background in the absence of collisions was recorded. The possibility of superalfvenic flow interactions (Msub(A)> or approximately 6) at the expense of the independent from Msub(A) magnetic laminar mechanism of ion acceleration by vortex electric field is proved experimentally

  14. Novel Methods for Measuring Depth of Anesthesia by Quantifying Dominant Information Flow in Multichannel EEGs

    Directory of Open Access Journals (Sweden)

    Kab-Mun Cha

    2017-01-01

    Full Text Available In this paper, we propose novel methods for measuring depth of anesthesia (DOA by quantifying dominant information flow in multichannel EEGs. Conventional methods mainly use few EEG channels independently and most of multichannel EEG based studies are limited to specific regions of the brain. Therefore the function of the cerebral cortex over wide brain regions is hardly reflected in DOA measurement. Here, DOA is measured by the quantification of dominant information flow obtained from principle bipartition. Three bipartitioning methods are used to detect the dominant information flow in entire EEG channels and the dominant information flow is quantified by calculating information entropy. High correlation between the proposed measures and the plasma concentration of propofol is confirmed from the experimental results of clinical data in 39 subjects. To illustrate the performance of the proposed methods more easily we present the results for multichannel EEG on a two-dimensional (2D brain map.

  15. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Goel, A., E-mail: ashish09@stanford.edu; Tarantino, P. M.; Lauben, D. S.; Close, S. [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States)

    2015-04-15

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  16. 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.

  17. Hybrid simulations of current-carrying instabilities in Z-pinch plasmas with sheared axial flow

    International Nuclear Information System (INIS)

    Sotnikov, Vladimir I.; Makhin, Volodymyr; Bauer, Bruno S.; Hellinger, Petr; Travnicek, Pavel; Fiala, Vladimir; Leboeuf, Jean-Noel

    2002-01-01

    The development of instabilities in z-pinch plasmas has been studied with three-dimensional (3D) hybrid simulations. Plasma equilibria without and with sheared axial flow have been considered. Results from the linear phase of the hybrid simulations compare well with linear Hall magnetohydrodynamics (MHD) calculations for sausage modes. The hybrid simulations show that sheared axial flow has a stabilizing effect on the development of both sausage and kink modes

  18. Plasma flow measurements in a simulated low earth orbit plasma

    International Nuclear Information System (INIS)

    Gabriel, S.B.; Mccoy, J.E.; Carruth, M.R. Jr.

    1982-01-01

    The employment of large, higher power solar arrays for space operation has been considered, taking into account a utilization of high operating voltages. In connection with the consideration of such arrays, attention must be given to the fact that the ambient environment of space contains a tenuous low energy plasma which can interact with the high voltage array causing power 'leakage' and arcing. An investigation has been conducted with the aim to simulate the behavior of such an array in low-earth-orbit (LEO). During the experiments, local concentrations of the 'leakage' current were observed when the panel was at a high voltage. These concentrations could overload or damage a small area of cells in a large string. It was hypothesized that this effect was produced by electrostatic focusing of the particles by the sheath fields. To verify this experimentally, an end-effect Langmuir probe was employed. The obtained results are discussed

  19. Two-dimensional LIF measurements of humidity and OH density resulting from evaporated water from a wet surface in plasma for medical use

    International Nuclear Information System (INIS)

    Yagi, Ippei; Ono, Ryo; Oda, Tetsuji; Takaki, Koichi

    2015-01-01

    In plasma medicine, plasma is applied to a wet surface and is often accompanied by dry-gas flow. The dry-gas flow affects water evaporation from the wet surface and influences production of reactive species derived from water vapor, such as OH radicals. In this study, the effect of the dry-gas flow on two-dimensional distributions of humidity and OH radical density are examined by measuring them using laser-induced fluorescence (LIF). First, humidity is measured when nitrogen flows from a quartz tube of 4 mm inner diameter onto distilled water and agar media from 5 mm distance. NO gas is added to the nitrogen as a tracer and humidity is obtained from the quenching rate of NO molecules measured using LIF. This measurement has a spatial resolution of 0.2 mm 3 and a temporal resolution of less than 220 ns. The two-dimensional humidity distribution shows that the dry-gas flow pushes away water vapor evaporating from the wet surface. As a result, a low-humidity region is formed near the quartz tube nozzle and a high-humidity region is formed near the wet surface. The thickness of the low-humidity region reduces with increasing gas flow rate. It is 0.1–0.5 mm for the flow rate of higher than 0.3 l min −1 . Next, the OH density is measured when a nanosecond pulsed streamer discharge is applied to a distilled water surface with dry-air flow. The OH density decreases with increasing gas flow rate due to decreased humidity. When the flow rate is lower than 0.1 l min −1 , the OH distribution is approximately uniform in the plasma region, while the humidity distribution shows a large gradient. The importance of the thin high-humidity region on the flux of reactive species onto the wet surface is discussed. (paper)

  20. Diagnostic system for EUV radiation measurements from dense xenon plasma generated by MPC

    International Nuclear Information System (INIS)

    Petrov, Yu.V.; Garkusha, I.E.; Solyakov, D.G.; Marchenko, A.K.; Chebotarev, V.V.; Ladygina, M.S.; Staltsov, V.V.; Yelisyeyev, D.V.; Hassanein, A.

    2011-01-01

    Magnetoplasma compressor (MPC) of compact geometry has been designed and tested as a source of EUV radiation. In present paper diagnostic system for registration of EUV radiation is described. It was applied for radiation measurements in different operation modes of MPC. The registration system was designed on the base of combination of different types of AXUV photodiodes. Possibility to minimize the influence of electrons and ions flows from dense plasma stream on AXUV detector performance and results of the measurements has been discussed.

  1. Measurements of secondary emissions from plasma arc and laser cutting in standard experiments

    International Nuclear Information System (INIS)

    Pilot, G.; Noel, J.P.; Leautier, R.; Steiner, H.; Tarroni, G.; Waldie, B.

    1992-01-01

    As part of an inter-facility comparison of secondary emissions from plasma arc and laser-cutting techniques, standard cutting tests have been done by plasma arc underwater and in air, and by laser beam in air. The same team was commissioned to measure the secondary emissions (solid and gaseous) in each contractor's facility with the same measuring rig. 20 mm and 40 mm thick, grade 304 stainless-steel plates were cut by plasma-torch in three different facilities: Heriot Watt University of Edinburgh, Institut fuer Werkstoffkunde of Universitaet Hannover and CEA/CEN Cadarache. 10 mm and in some cases 20 mm thick, grade 304, stainless-steel plates were cut by laser beam in five different facilities: CEA-CEN Fontenay, CEA-CEN Saclay, Institut fuer Werkstoffkunde of Universitaet Hannover and ENEA/Frascati. The results obtained in the standard experiments are rather similar, and the differences that appear can be explained by the various scales of the involved facilities (semi-industrial and laboratory) and by some particularities in the cutting parameters (an additional secondary gas flow of oxygen in plasma cutting at Universitaet Hannover, for example)

  2. Measurements of secondary emissions from plasma arc and laser cutting in standard experiments

    International Nuclear Information System (INIS)

    Pilot, G.; Noel, M.; Leautier, R.; Steiner, H.; Tarroni, G.; Waldie, B.

    1990-01-01

    As part of an inter-facility comparison of secondary emissions from plasma-arc and laser cutting techniques, standard cutting tests have been done by plasma arc underwater and in air and laser beam in air. The same team, CEA/DPT/SPIN, was commissioned to measure the secondary emissions (solid and gaseous) in each contractor's facility with the same measuring rig. 20 mm and 40 mm thick grade 304 stainless steel plates were cut by plasma-torch in three different facilities: Heriot Watt University of Edinburgh, Institute fuer Werkstoffkunde of Hannover and CEA/CEN Cadarache. 10 mm and sometimes 20 mm thick grade 304 stainless steel plates were cut by laser beam in four different facilities: CEA/CEN Fontenay, CEA/CEN Saclay, Institute fuer Werkstoffkunde of Hannover and ENEA/FRASCATI. The results obtained in the standard experiments are rather similar, the differences that appear can be explained by the various scales of the facilities (semi-industrial and laboratory scale) and by some particularity in the cutting parameters (additional secondary gas flow of oxygen in plasma cutting at Hannover for example). Some supplementary experiments show the importance of some cutting parameters. (author)

  3. An analytic model for flow reversal in divertor plasmas

    International Nuclear Information System (INIS)

    Cooke, P.I.H.; Prinja, A.K.

    1987-04-01

    An analytic model is developed and used to study the phenomenon of flow reversal which is observed in two-dimensional simulations of divertor plasmas. The effect is shown to be caused by the radial spread of neutral particles emitted from the divertor target which can lead to a strong peaking of the ionization source at certain radial locations. The results indicate that flow reversal over a portion of the width of the scrape-off layer is inevitable in high recycling conditions. Implications for impurity transport and particle removal in reactors are discussed

  4. Flow Rate Measurement in Multiphase Flow Rig: Radiotracer and Conventional

    International Nuclear Information System (INIS)

    Nazrul Hizam Yusoff; Noraishah Othman; Nurliyana Abdullah; Amirul Syafiq Mohd Yunos; Rasif Mohd Zain; Roslan Yahya

    2015-01-01

    Applications of radiotracer technology are prevalent throughout oil refineries worldwide, and this industry is one of the main users and beneficiaries of the technology. Radioactive tracers have been used to a great extent in many applications i.e. flow rate measurement, RTD, plant integrity evaluation and enhancing oil production in oil fields. Chemical and petrochemical plants are generally continuously operating and technically complex where the radiotracer techniques are very competitive and largely applied for troubleshooting inspection and process analysis. Flow rate measurement is a typical application of radiotracers. For flow measurements, tracer data are important, rather than the RTD models. Research is going on in refining the existing methods for single phase flow measurement, and in developing new methods for multiphase flow without sampling. The tracer techniques for single phase flow measurements are recognized as ISO standards. This paper presents technical aspect of laboratory experiments, which have been carried out using Molybdenum-99 - Mo99 (radiotracer) to study and determine the flow rate of liquid in multiphase flow rig. The multiphase flow rig consists of 58.7 m long and 20 cm diameter pipeline that can accommodate about 0.296 m 3 of liquid. Tap water was used as liquid flow in pipeline and conventional flow meters were also installed at the flow rig. The flow rate results; radiotracer and conventional flow meter were compared. The total count method was applied for radiotracer technique and showed the comparable results with conventional flow meter. (author)

  5. Characterisation of target plasma required for REB-plasma interaction studies using cylindrical Langmuir probes

    International Nuclear Information System (INIS)

    Roychowdhury, P.; Paithankar, A.S.; Iyyengar, S.K.; Rohatgi, V.K.

    1987-01-01

    The target plasma required for relativistic electron beam (REB)-plasma interaction studies has been generated by coaxial plasma gun. The measurement of electron density and temperature has been carried out using cylindrical Langmuir probes. Probes both oriented parallel and transverse to the flow have been used. The spatial as well as temporal variation of electron density and temperature have been studied. The typical electron density and temperature measured by probe were in the range of 9.0-3.5 x 10 13 cm -3 and 5-7 eV respectively. The typical e-folding decay time of density was 6.2 μs, while no appreciable change in electron temperature was observed until 10 μs after the peak density. The density decays by about 50% at distance of 30 cm from the gun. The plasma flow velocity has been measured by the time of flight technique and was found to be 2.5 x 10 6 cm s -1 . The plasma radius measured by dosimeter film, at distance of 30 cm from the gun was 3 cm. (author)

  6. Measurement of temperature, electric conductivity and density of plasma

    International Nuclear Information System (INIS)

    Vasilevova, I.; Nefedov, A.; Oberman, F.; Urinson, A.

    1982-01-01

    Three instruments are briefly described developed by the High Temperatures Institute of the USSR Academy of Sciences for the measurement of plasma temperature, electric conductivity and density. The temperature measuring instrument uses as a standard a light source whose temperature may significantly differ from plasma temperature because three light fluxes are compared, namely the flux emitted by the plasma, the flux emitted directly by the standard source, and the flux emitted by the standard source after passage through the plasma. The results of measurement are computer processed. Electric conductivity is measured using a coil placed in a probe which is automatically extended for a time of maximally 0.3 seconds into the plasma stream. The equipment for measuring plasma density consists of a special single-channel monochromator, a temperature gauge, a plasma pressure gauge, and of a computer for processing the results of measurement. (Ha)

  7. Plasma-parameter measurements using neutral-particle-beam attenuation

    International Nuclear Information System (INIS)

    Foote, J.H.; Molvik, A.W.; Turner, W.C.

    1982-01-01

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane

  8. Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jaiswal, S., E-mail: surabhijaiswal73@gmail.com; Bandyopadhyay, P.; Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-08-15

    We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger the onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.

  9. Interpretation of the molecular fluxes measured at the periphery of a magnetically confined plasma

    International Nuclear Information System (INIS)

    Liu-Hinz, C.; Terreault, B.; Martin, F.

    1995-01-01

    A new instrument (''Variable Geometry Sniffer Probe'' or VGSP), allowing one to sample and mass analyse atoms, ions or molecules moving in different directions and at different locations at the periphery of a plasma, has been built and used in plasma edge studies in the TdeV tokamak. Three different regimes of particle sampling have been identified. First, the VGSP can measure the fluxes of hydrogen and impurity molecules issuing from the walls. Second, it has the capability of detecting low energy charge-exchange and Franck-Condon neutrals. Finally, there is a parallel ion flux sampling regime, for which it is shown that both the connection lengths to the divertor plates and the ExB plasma flows induced by edge electric fields play major roles. ((orig.))

  10. Estimation of the quantification uncertainty from flow injection and liquid chromatography transient signals in inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Laborda, Francisco; Medrano, Jesus; Castillo, Juan R.

    2004-01-01

    The quality of the quantitative results obtained from transient signals in high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) and flow injection-inductively coupled plasma mass spectrometry (FI-ICPMS) was investigated under multielement conditions. Quantification methods were based on multiple-point calibration by simple and weighted linear regression, and double-point calibration (measurement of the baseline and one standard). An uncertainty model, which includes the main sources of uncertainty from FI-ICPMS and HPLC-ICPMS (signal measurement, sample flow rate and injection volume), was developed to estimate peak area uncertainties and statistical weights used in weighted linear regression. The behaviour of the ICPMS instrument was characterized in order to be considered in the model, concluding that the instrument works as a concentration detector when it is used to monitorize transient signals from flow injection or chromatographic separations. Proper quantification by the three calibration methods was achieved when compared to reference materials, although the double-point calibration allowed to obtain results of the same quality as the multiple-point calibration, shortening the calibration time. Relative expanded uncertainties ranged from 10-20% for concentrations around the LOQ to 5% for concentrations higher than 100 times the LOQ

  11. Measurement of Debye length in laser-produced plasma.

    Science.gov (United States)

    Ehler, W.

    1973-01-01

    The Debye length of an expanded plasma created by placing an evacuated chamber with an entrance slit in the path of a freely expanding laser produced plasma was measured, using the slab geometry. An independent measurement of electron density together with the observed value for the Debye length also provided a means for evaluating the plasma electron temperature. This temperature has applications in ascertaining plasma conductivity and magnetic field necessary for confinement of the laser produced plasma. Also, the temperature obtained would be useful in analyzing electron-ion recombination rates in the expanded plasma and the dynamics of the cooling process of the plasma expansion.

  12. Shear flow instability in a partially-ionized plasma sheath around a fast-moving vehicle

    International Nuclear Information System (INIS)

    Sotnikov, V. I.; Mudaliar, S.; Genoni, T. C.; Rose, D. V.; Oliver, B. V.; Mehlhorn, T. A.

    2011-01-01

    The stability of ion acoustic waves in a sheared-flow, partially-ionized compressible plasma sheath around a fast-moving vehicle in the upper atmosphere, is described and evaluated for different flow profiles. In a compressible plasma with shear flow, instability occurs for any velocity profile, not just for profiles with an inflection point. A second-order differential equation for the electrostatic potential of excited ion acoustic waves in the presence of electron and ion collisions with neutrals is derived and solved numerically using a shooting method with boundary conditions appropriate for a finite thickness sheath in contact with the vehicle. We consider three different velocity flow profiles and find that in all cases that neutral collisions can completely suppress the instability.

  13. Improvement of the Performance of Graphite Felt Electrodes for Vanadium-Redox-Flow-Batteries by Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Eva-Maria Hammer

    2014-02-01

    Full Text Available In the frame of the present contribution oxidizing plasma pretreatment is used for the improvement of the electrocatalytic activity of graphite felt electrodes for Vanadium-Redox-Flow-Batteries (VRB. The influence of the working gas media on the catalytic activity and the surface morphology is demonstrated. The electrocatalytical properties of the graphite felt electrodes were examined by cyclic voltammetry and electrochemical impedance spectroscopy. The obtained results show that a significant improvement of the redox reaction kinetics can be achieved for all plasma modified samples using different working gasses (Ar, N2 and compressed air in an oxidizing environment. Nitrogen plasma treatment leads to the highest catalytical activities at the same operational conditions. Through a variation of the nitrogen plasma treatment duration a maximum performance at about 14 min cm-2 was observed, which is also represented by a minimum of 90 Ω in the charge transfer resistance obtained by EIS measurements. The morphology changes of the graphitized surface were followed using SEM.

  14. Identification and Characterization of Plasma Cells in Normal Human Bone Marrow by High-Resolution Flow Cytometry

    NARCIS (Netherlands)

    Terstappen, Leonardus Wendelinus Mathias Marie; Johnsen, Steen; Segers-Nolten, Gezina M.J.; Loken, Michael R.

    1990-01-01

    The low frequency of plasma cells and the lack of specific cell surface markers has been a major obstacle for a detailed characterization of plasma cells in normal human bone marrow. Multiparameter flow cytometry enabled the identification of plasma cells in normal bone marrow aspirates. The plasma

  15. Meridional flow in the solar convection zone. I. Measurements from gong data

    Energy Technology Data Exchange (ETDEWEB)

    Kholikov, S. [National Solar Observatories, Tucson, AZ 85719 (United States); Serebryanskiy, A. [Ulugh Beg Astronomical Institute, Uzbek Academy of Science, Tashkent 100052 (Uzbekistan); Jackiewicz, J., E-mail: kholikov@noao.edu [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)

    2014-04-01

    Large-scale plasma flows in the Sun's convection zone likely play a major role in solar dynamics on decadal timescales. In particular, quantifying meridional motions is a critical ingredient for understanding the solar cycle and the transport of magnetic flux. Because the signal of such features can be quite small in deep solar layers and be buried in systematics or noise, the true meridional velocity profile has remained elusive. We perform time-distance helioseismology measurements on several years worth of Global Oscillation Network Group Doppler data. A spherical harmonic decomposition technique is applied to a subset of acoustic modes to measure travel-time differences to try to obtain signatures of meridional flows throughout the solar convection zone. Center-to-limb systematics are taken into account in an intuitive yet ad hoc manner. Travel-time differences near the surface that are consistent with a poleward flow in each hemisphere and are similar to previous work are measured. Additionally, measurements in deep layers near the base of the convection zone suggest a possible equatorward flow, as well as partial evidence of a sign change in the travel-time differences at mid-convection zone depths. This analysis on an independent data set using different measurement techniques strengthens recent conclusions that the convection zone may have multiple 'cells' of meridional flow. The results may challenge the common understanding of one large conveyor belt operating in the solar convection zone. Further work with helioseismic inversions and a careful study of systematic effects are needed before firm conclusions of these large-scale flow structures can be made.

  16. Investigating plasma-rotation methods for the Space-Plasma Physics Campaign at UCLA's BAPSF.

    Science.gov (United States)

    Finnegan, S. M.; Koepke, M. E.; Reynolds, E. W.

    2006-10-01

    In D'Angelo et al., JGR 79, 4747 (1974), rigid-body ExB plasma flow was inferred from parabolic floating-potential profiles produced by a spiral ionizing surface. Here, taking a different approach, we report effects on barium-ion azimuthal-flow profiles using either a non-emissive or emissive spiral end-electrode in the WVU Q-machine. Neither electrode produced a radially-parabolic space-potential profile. The emissive spiral, however, generated controllable, radially-parabolic structure in the floating potential, consistent with a second population of electrons having a radially-parabolic parallel-energy profile. Laser-induced-fluorescence measurements of spatially resolved, azimuthal-velocity distribution functions show that, for a given flow profile, the diamagnetic drift of hot (>>0.2eV) ions overwhelms the ExB-drift contribution. Our experiments constitute a first attempt at producing controllable, rigid-body, ExB plasma flow for future experiments on the LArge-Plasma-Device (LAPD), as part of the Space-Plasma Physics Campaign (at UCLA's BAPSF).

  17. Effects of plasma current on nonlinear interactions of ITG turbulence, zonal flows and geodesic acoustic modes

    International Nuclear Information System (INIS)

    Angelino, P; Bottino, A; Hatzky, R; Jolliet, S; Sauter, O; Tran, T M; Villard, L

    2006-01-01

    The mutual interactions of ion temperature gradient (ITG) driven modes, zonal flows and geodesic acoustic modes (GAM) in tokamak plasmas are investigated using a global nonlinear gyrokinetic formulation with totally unconstrained evolution of temperature gradient and profile. A series of numerical simulations with the same initial temperature and density profile specifications is performed using a sequence of ideal MHD equilibria differing only in the value of the total plasma current, in particular with identical magnetic shear profiles and shapes of magnetic surfaces. On top of a bursty or quasi-steady state behaviour the zonal flows oscillate at the GAM frequency. The amplitude of these oscillations increases with the value of the safety factor q, resulting in a less effective suppression of ITG turbulence by zonal flows at a lower plasma current. The turbulence-driven volume-averaged radial heat transport is found to scale inversely with the total plasma current

  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. Supersonic plasma flow between high latitude conjugate ionospheres

    International Nuclear Information System (INIS)

    Roesler, G.

    1975-01-01

    The polar wind problem has been investigated for closed field lines in situations where one of the two conjugate ionospheric regions is fully illuminated by the sun and the other darkness (solstices at high latitudes). A supersonic flow between hemispheres is possible; the magnetospheric part of this flow must be symmetric with respect to the equator. The daytime fluxes are proportional to the neutral hydrogen density. Fluxes of the order of 10 8 cm -2 sec -1 are only possible with density considerably higher than given by CIRA models. For stationary solutions higher flow speeds are needed on the dark side than provided from the illuminated side. It is concluded that shock waves with upward velocities of about 5 km/sec would form above the dark ionosphere. This implies a reduction by a factor of 3 to 5 of the plasma influx into the dark hemisphere, whereby F-layer densities of only up to 2 x 10 4 cm -3 can be maintained. (orig.) [de

  20. Eddy-current flow rate meter for measuring sodium flow rates

    International Nuclear Information System (INIS)

    Knaak, J.

    1976-01-01

    For safety reasons flow rate meters for monitoring coolant flow rates are inserted in the core of sodium-cooled fast breeder reactors. These are so-called eddy-current flow rate meters which can be mounted directly above the fuel elements. In the present contribution the principle of measurement, the mechanical construction and the circuit design of the flow rate measuring device are described. Special problems and their solution on developing the measuring system are pointed out. Finally, results of measurement and experience with the apparatus in several experiments are reported, where also further possibilities of application were tested. (orig./TK) [de

  1. The mitigation effect of sheared axial flow on the rayleigh-taylor instability in Z-pinch plasma

    International Nuclear Information System (INIS)

    Zhang Yang

    2005-01-01

    A magnetohydrodynamic formulation is derived to investigate the mitigation effects of the sheared axial flow on the Rayleigh-Taylor (RT) instability in Z-pinch plasma. The dispersion relation of the compressible model is given. The mitigation effects of sheared axial flow on the Rayleigh-Taylor instability of Z-pinch plasma in the compressible and incompressible models are compared respectively, and the effect of compressible on the instability of system with sheared axial flow is discussed. It is found that, compressibility effects can stabilize the Rayleigh-Taylor/Kelvin-Helmholtz (RT/KH) instability, and this allows the sheared axial flow mitigate the RT instability far more effectively. The authors also find that, at the early stage of the implosion, if the temperature of the plasma is not very high, the compressible model is much more suitable to describing the state of system than the incompressible one. (author)

  2. High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena

    Science.gov (United States)

    Li, Zhaorui; Livescu, Daniel

    2017-11-01

    The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

  3. Calculation of gas-flow in plasma reactor for carbon partial oxidation

    Science.gov (United States)

    Bespala, Evgeny; Myshkin, Vyacheslav; Novoselov, Ivan; Pavliuk, Alexander; Makarevich, Semen; Bespala, Yuliya

    2018-03-01

    The paper discusses isotopic effects at carbon oxidation in low temperature non-equilibrium plasma at constant magnetic field. There is described routine of experiment and defined optimal parameters ensuring maximum enrichment factor at given electrophysical, gas-dynamic, and thermodymanical parameters. It has been demonstrated that at high-frequency generator capacity of 4 kW, supply frequency of 27 MHz and field density of 44 mT the concentration of paramagnetic heavy nuclei 13C in gaseous phase increases up to 1.78 % compared to 1.11 % for natural concentration. Authors explain isotopic effect decrease during plasmachemical separation induced by mixing gas flows enriched in different isotopes at the lack of product quench. With the help of modeling the motion of gas flows inside the plasma-chemical reactor based on numerical calculation of Navier-Stokes equation authors determine zones of gas mixing and cooling speed. To increase isotopic effects and proportion of 13C in gaseous phase it has been proposed to use quench in the form of Laval nozzle of refractory steel. The article represents results on calculation of optimal Laval Nozzle parameters for plasma-chemical reactor of chosen geometry of. There are also given dependences of quench time of products on pressure at the diffuser output and on critical section diameter. Authors determine the location of quench inside the plasma-chemical reactor in the paper.

  4. In search of zonal flows using cross-bispectrum analysis in the boundary plasma of the Hefei Tokamak-7

    International Nuclear Information System (INIS)

    Xu, G.S.; Wan, B.N.; Song, M.

    2002-01-01

    Langmuir probes have been used to measure the electrostatic Reynolds stress and the floating potential fluctuation in the boundary plasma of the Hefei Tokamak-7 (HT-7) [J. Li, B. N. Wan, and J. S. Mao, Plasma Phys. Controlled Fusion 42, 135 (2000)]. The cross bispectrum of r V(tilde sign) θ φ(tilde sign) f > indicates the existence of difference-frequency nonlinear phase coupling and the generation of fluctuations near the geodesic acoustic mode frequency. The inverse cascade process might be linked to the generation of zonal flows by small-scale electrostatic drift-wave turbulence

  5. Exploring liquid metal plasma facing component (PFC) concepts-Liquid metal film flow behavior under fusion relevant magnetic fields

    International Nuclear Information System (INIS)

    Narula, M.; Abdou, M.A.; Ying, A.; Morley, N.B.; Ni, M.; Miraghaie, R.; Burris, J.

    2006-01-01

    The use of fast moving liquid metal streams or 'liquid walls' as a plasma contact surface is a very attractive option and has been looked upon with considerable interest over the past several years, both by the plasma physics and fusion engineering programs. Flowing liquid walls provide an ever replenishing contact surface to the plasma, leading to very effective particle pumping and surface heat flux removal. A key feasibility issue for flowing liquid metal plasma facing component (PFC) systems, pertains to their magnetohydrodynamic (MHD) behavior under the spatially varying magnetic field environment, typical of a fusion device. MHD forces hinder the development of a smooth and controllable liquid metal flow needed for PFC applications. The present study builds up on the ongoing research effort at UCLA, directed towards providing qualitative and quantitative data on liquid metal free surface flow behavior under fusion relevant magnetic fields

  6. On the link between ExB sheared flows and rational surfaces in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Erents, K.; Matthews, G.

    2000-11-01

    Experimental evidence of flattening in plasma profiles has been observed in the edge region of the JET tokamak. This observation has been interpreted in terms of the influence of rational surfaces on plasma profiles. In the framework of this interpretation, significant ExB sheared flows linked to rational surfaces have been identified. These ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. These results can explain the link between the magnetic topology and the generation of transport barriers reported in fusion devices. (author)

  7. Rational surfaces, ExB sheared flows and transport interplay in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Pedrosa, M.A.; Erents, K.

    2002-01-01

    Experimental evidence of a strong interplay between magnetic topology (rational surfaces) and the generation of ExB sheared flows has been observed in the plasma edge region of stellarator (TJ-II) and tokamak (JET) devices. Both constant and varying in time ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes, but below the power threshold to trigger the formation of transport barriers. Flows driven by fluctuations are candidates to explain these experimental results. (author)

  8. Surface wave propagation in an ideal Hall-magnetohydrodynamic plasma jet in flowing environment

    International Nuclear Information System (INIS)

    Sikka, Himanshu; Kumar, Nagendra; Zhelyazkov, Ivan

    2004-01-01

    The behavior of the Hall-magnetohydrodynamic (Hall-MHD) sausage and kink waves is studied in the presence of steady flow. The influence of the flow both inside and outside the plasma slab is taken into account. The plasma in the environment is considered to be cold and moves with the different flow velocity outside the slab. In the limit of parallel propagation, dispersion relation is derived to discuss the propagation of both the modes. Numerical results for the propagation characteristics are obtained for different Alfvenic Mach number ratios inside and outside the slab. It is found that the dispersion curves for both surface modes, namely, the sausage and kink ones in cold plasma show complexities in their behavior in terms of multivalued portions of the curves. These multivalued portions correspond to the different normalized phase velocities for the same value of Alfvenic Mach number. In contrast to the conventional MHD surface waves which are assumed to be pure surface waves or pseudosurface waves, surface waves are obtained which are bulk waves for very small dimensionless wave numbers, then turn to leaky waves and finally transform to pure surface waves for values of dimensionless wave number greater than one

  9. Modeling of plasma flow switches at low, intermediate and high energies

    International Nuclear Information System (INIS)

    Bowers, R.L.; Brownell, J.H.; Greene, A.E.; Peterson, D.L.; Roderick, N.; Turchi, P.

    1992-01-01

    Inductively stored pulsed power technology has been used over the past thirty years to produce multi-megaamp currents to implode low inductance loads and produce x-radiation. Because of the large difference in timescales for the delivery of magnetic energy to the load and the desire for high power x-radiation output (short timescale for the implosion), most inductively stored systems require at least one opening switch. The design and understanding of fast, efficient opening switches for multi-megaamp systems represents a long standing problem in pulsed power research. The Los Alamos Foil Implosion Project uses inductively stored magnetic energy to implode thin metallic liners. A plasma flow switch (PFS) has been investigated as the final pulse shaping step for this systems. The PFS consists of a wire array and a barrier foil located upstream from the load region. Several stages can be identified in the performance of the plasma flow switch. These are: (1) the vaporization of the wire array; (2) the assembly of the initiated plasma on tie barrier foil to form the switch plasma; (3) the motion of the switch plasma down the coaxial barrel; and (4) current switching to the load (the actual switching stage). The fourth stage affects the switch's efficiency, as well as the quality of the load implosion. Instabilities may develop during any of these four stages, and their presence may seriously degrade the structure of the switch plasma. Two primary criteria may be used to characterize good switching. The first is switching efficiency. A second criterion is transferred to the load during or after switching. This paper summarizes the computational design of the PFS experiments carried out on Pegasus 1. We conclude by considering the implications of these results for the design of a PFS for the higher energy regime (Procyon) regime

  10. Flow-Induced New Channels of Energy Exchange in Multi-Scale Plasma Dynamics - Revisiting Perturbative Hybrid Kinetic-MHD Theory.

    Science.gov (United States)

    Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go

    2016-05-10

    It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle's Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas.

  11. Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

    International Nuclear Information System (INIS)

    Zarchin, O; Zhitomirsky, V N; Goldsmith, S; Boxman, R L

    2003-01-01

    The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of a vacuum arc plasma source, a straight plasma duct, and a multi-probe consisting of a removable disc obstacle and a set of ring probes for measuring the radial ion flux. A dc arc discharge was ignited in vacuum between a truncated cone-shaped Cu cathode and an annular anode. The plasma jet produced by cathode spots passed through the anode aperture into the straight plasma duct. An axial magnetic field guided the plasma jet in the duct. The multi-probe consisted of a removable disc obstacle and a set of five ring probes for measuring the radial plasma flux as a function of distance from the disc obstacle. The rings and the disc probes were coaxially arranged on the multi-probe assembly and positioned so that plasma from the source passed through the ring probes and then encountered the disc. The influence of the obstacle was determined by measuring the ring ion currents, both in the presence of the obstacle, and when the disc obstacle was removed. The difference between the measured ion currents with and without the obstacle was interpreted to be the contribution of reflected or sputtered particles from the obstacle to the radial ion flux. The ring probes were biased by -60 V with respect to the grounded anode, to collect the saturated ion current. The multi-probe was connected to a movable stem, and positioned at different distances from the plasma source. A plasma density of ∼6 x 10 17 m -3 was estimated in this study based on the ion current to the obstacle. The radial ion flux collected by the ring probes increased by 20-25% due to the presence of the obstacle. As the calculated mean free path for

  12. Relaxation with high-speed plasma flows and singularity analysis in MHD equilibrium

    International Nuclear Information System (INIS)

    Shiraishi, Junya; Ohsaki, Shuichi; Yoshida, Zensho

    2004-01-01

    Relaxation model that leads to plasma confinement with rigid-rotation is presented. This model applies to Jupiter's magnetosphere. It is shown that the invariance of canonical angular momentum of electron fluid, which is realized by axisymmetry through self-organization process, yields plasma confinement. including poloidal flows in equilibrium equation makes the problem rather complicated. Singularity due to the poloidal flow is focused on. It is shown that the singular equation for equilibrium has the same structure as the equation for linear Alfven wave. Since the singular solution for equilibrium equation is physically inadequate, the singularity may be removed by another physical effect. The Hall-effect is taken into account as a singular perturbation that removes the singularity of equilibrium equation for ideal magnetohydrodynamics. (author)

  13. Assessment of glomerular filtration rate and effective renal plasma flow in cystic fibrosis

    International Nuclear Information System (INIS)

    Spino, M.; Chai, R.P.; Isles, A.F.; Balfe, J.W.; Brown, R.G.; Thiessen, J.J.; MacLeod, S.M.

    1985-01-01

    A study was conducted to examine renal function in 10 healthy control subjects and eight patients with cystic fibrosis in stable condition. Sequential bolus injections of /sup 99m/Tc-DTPA and 125 I-OIH were administered to assess glomerular filtration rate and effective renal plasma flow, respectively. Blood was subsequently collected for 3 hours, and urine for 24 hours. Renal clearances of both radioisotope markers were virtually identical in patients and controls. Inasmuch as neither glomerular filtration rate nor effective renal plasma flow was enhanced in patients with cystic fibrosis, increased clearance of drugs in these patients is unlikely to be the result of enhanced glomerular filtration or tubular secretion

  14. Interferometric measurements of plasma density in high-β plasmas

    International Nuclear Information System (INIS)

    Quinn, W.E.

    1977-01-01

    The coupled-cavity laser interferometer technique is particularly applicable to the measurement of pulsed plasma densities. This technique is based on the fact that if a small fraction of a gas laser's output radiation is reflected into the laser with an external mirror, the intensity of the laser output is modulated. These amplitude or intensity modulations are produced by changes in the laser gain. A rotating corner mirror or an oscillating mirror can be used to produce a continuous feedback modulation of the interferometer which produces a continuous background fringe pattern. The presence of plasma in the outer cavity causes an additional change which results in a phase shift of the regular period of the background fringe pattern. The integral of the plasma density along the line of sight can be evaluated by comparison of the time history of the fringes obtained with and without plasma

  15. Plasma-cavity ringdown spectroscopy for analytical measurement: Progress and prospectives

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Sida; Liu, Wei [Research Center of Analytical Instrumentation, Analytical and Testing Center, College of Chemistry, Sichuan University, Chengdu (China); Zhang, Xiaohe [College of Water Resources and Hydropower, Sichuan University, Chengdu (China); Duan, Yixiang, E-mail: yduan@scu.edu.cn [Research Center of Analytical Instrumentation, Analytical and Testing Center, College of Chemistry, Sichuan University, Chengdu (China)

    2013-07-01

    Plasma-cavity ringdown spectroscopy is a powerful absorption technique for analytical measurement. It combines the inherent advantages of high sensitivity, absolute measurement, and relative insensitivity to light source intensity fluctuations of the cavity ringdown technique with use of plasma as an atomization/ionization source. In this review, we briefly describe the background and principles of plasma-cavity ringdown spectroscopy(CRDS) technology, the instrumental components, and various applications. The significant developments of the plasma sources, lasers, and cavity optics are illustrated. Analytical applications of plasma-CRDS for elemental detection and isotopic measurement in atomic spectrometry are outlined in this review. Plasma-CRDS is shown to have a promising future for various analytical applications, while some further efforts are still needed in fields such as cavity design, plasma source design, instrumental improvement and integration, as well as potential applications in radical and molecular measurements. - Highlights: • Plasma-based cavity ringdown spectroscopy • High sensitivity and high resolution • Elemental and isotopic measurements.

  16. Reexamination of plasma measurements from the Mariner 5 Venus encounter

    International Nuclear Information System (INIS)

    Shefer, R.E.; Lazarus, A.J.; Bridge, H.S.

    1979-01-01

    Mariner 5 plasma data from the Venus encounter have been analyzed with twice the time resolution of the original analysis of Bridge et al. (1967). The velocity distribution function for each spectrum is used to determine more precisely the locations of boundaries and characteristic flow parameters in the interaction region around the planet. We identify a new region in the flow located between magnetosheathlike plasma inside the shock front and an interior low-flux region near the geometrical shadow of the planet. The region is characterized by a wide velocity distribution function and a decrease in ion flux. Using the highest time resolution magnetic field data made available by Smith et al., we propose that rapid magnetic field fluctuations in this region may result in an artificial broadening of the distribution function. We conclude that very high time resolution is required in future experiments in order to determine the true nature of the plasma in this region

  17. Opacity measurements in shock-generated argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

  18. Plasma assisted measurements of alkali metal concentrations in pressurised combustion processes

    Energy Technology Data Exchange (ETDEWEB)

    Hernberg, R; Haeyrinen, V [Tampere Univ. of Technology (Finland)

    1997-10-01

    In this project the continuous alkali measurement method plasma excited alkali resonance line spectroscopy (PEARLS) was developed, tested and demonstrated in pressurised combustion facilities. The PEARLS method has been developed at Tampere University of Technology (TUT). During 1994-1996 the PEARLS method was developed from the laboratory level to an industrial prototype. The alkali measuring instrument has been tested and used for regular measurements in four different pressurised combustion installations ranging up to industrial pilot scale. The installations are: (1) a pressurised entrained flow reactor (PEFR) at VTT Energy in Jyvaeskylae, Finland (2) a pressurised fluidised bed combustion facility, called FRED, at DMT in Essen, Germany. (3) a 10 MW pressurised circulating fluidised bed combustion pilot plant at Foster Wheeler Energia Oy in Karhula, Finland (4) PFBC Research Facility at ABB Carbon in Finspaang, Sweden

  19. Ground Simulations of Near-Surface Plasma Field and Charging at the Lunar Terminator

    Science.gov (United States)

    Polansky, J.; Ding, N.; Wang, J.; Craven, P.; Schneider, T.; Vaughn, J.

    2012-12-01

    Charging in the lunar terminator region is the most complex and is still not well understood. In this region, the surface potential is sensitively influenced by both solar illumination and plasma flow. The combined effects from localized shadow generated by low sun elevation angles and localized wake generated by plasma flow over the rugged terrain can generate strongly differentially charged surfaces. Few models currently exist that can accurately resolve the combined effects of plasma flow and solar illumination over realistic lunar terminator topographies. This paper presents an experimental investigation of lunar surface charging at the terminator region in simulated plasma environments in a vacuum chamber. The solar wind plasma flow is simulated using an electron bombardment gridded Argon ion source. An electrostatic Langmuir probe, nude Faraday probes, a floating emissive probe, and retarding potential analyzer are used to quantify the plasma flow field. Surface potentials of both conducting and dielectric materials immersed in the plasma flow are measured with a Trek surface potential probe. The conducting material surface potential will simultaneously be measured with a high impedance voltmeter to calibrate the Trek probe. Measurement results will be presented for flat surfaces and objects-on-surface for various angles of attack of the plasma flow. The implications on the generation of localized plasma wake and surface charging at the lunar terminator will be discussed. (This research is supported by the NASA Lunar Advanced Science and Exploration Research program.)

  20. Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

    Science.gov (United States)

    Lempert, Walter R.; Adamovich, Igor V.

    2014-10-01

    The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed.

  1. On generation of Alfvenic-like fluctuations by drift wave-zonal flow system in large plasma device experiments

    International Nuclear Information System (INIS)

    Horton, W.; Correa, C.; Chagelishvili, G. D.; Avsarkisov, V. S.; Lominadze, J. G.; Perez, J. C.; Kim, J.-H.; Carter, T. A.

    2009-01-01

    According to recent experiments, magnetically confined fusion plasmas with ''drift wave-zonal flow turbulence'' (DW-ZF) give rise to broadband electromagnetic waves. Sharapov et al. [Europhysics Conference Abstracts, 35th EPS Conference on Plasma Physics, Hersonissos, 2008, edited by P. Lalousis and S. Moustaizis (European Physical Society, Switzerland, 2008), Vol. 32D, p. 4.071] reported an abrupt change in the magnetic turbulence during L-H transitions in Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] plasmas. A broad spectrum of Alfvenic-like (electromagnetic) fluctuations appears from ExB flow driven turbulence in experiments on the large plasma device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] facility at UCLA. Evidence of the existence of magnetic fluctuations in the shear flow region in the experiments is shown. We present one possible theoretical explanation of the generation of electromagnetic fluctuations in DW-ZF systems for an example of LAPD experiments. The method used is based on generalizing results on shear flow phenomena from the hydrodynamics community. In the 1990s, it was realized that fluctuation modes of spectrally stable nonuniform (sheared) flows are non-normal. That is, the linear operators of the flows modal analysis are non-normal and the corresponding eigenmodes are not orthogonal. The non-normality results in linear transient growth with bursts of the perturbations and the mode coupling, which causes the generation of electromagnetic waves from the drift wave-shear flow system. We consider shear flow that mimics tokamak zonal flow. We show that the transient growth substantially exceeds the growth of the classical dissipative trapped-particle instability of the system.

  2. Plasma flow switch and foil implosion experiments on Pegasus II

    International Nuclear Information System (INIS)

    Cochrane, J.C.; Bartsch, R.R.; Benage, J.R.; Forman, P.R.; Gribble, R.F.; Ladish, J.S.; Oona, H.; Parker, J.V.; Scudder, D.W.; Shlachter, J.S.; Wysocki, F.J.

    1993-01-01

    Pegasus II is the upgraded version of Pegasus, a pulsed power machine used in the Los Alamos AGEX (Above Ground EXperiments) program. A goal of the program is to produce an intense (> 100 TW) source of soft x-rays from the thermalization of the kinetic energy of a 1 to 10 MJ plasma implosion. The radiation pulse should have a maximum duration of several 10's of nanoseconds and will be used in the study of fusion conditions and material properties. The radiating plasma source will be generated by the thermalization of the kinetic energy of an imploding cylindrical, thin, metallic foil. This paper addresses experiments done on a capacitor bank to develop a switch (plasma flow switch) to switch the bank current into the load at peak current. This allows efficient coupling of bank energy into foil kinetic energy

  3. Reactor coolant flow measurements at Point Lepreau

    International Nuclear Information System (INIS)

    Brenciaglia, G.; Gurevich, Y.; Liu, G.

    1996-01-01

    The CROSSFLOW ultrasonic flow measurement system manufactured by AMAG is fully proven as reliable and accurate when applied to large piping in defined geometries for such applications as feedwater flows measurement. Its application to direct reactor coolant flow (RCF) measurements - both individual channel flows and bulk flows such as pump suction flow - has been well established through recent work by AMAG at Point Lepreau, with application to other reactor types (eg. PWR) imminent. At Point Lepreau, Measurements have been demonstrated at full power; improvements to consistently meet ±1% accuracy are in progress. The development and recent customization of CROSSFLOW to RCF measurement at Point Lepreau are described in this paper; typical measurement results are included. (author)

  4. Screening Effect of Plasma Flow on RMP Penetration in EXTRAP T2R

    Science.gov (United States)

    Frassinetti, Lorenzo; Olofsson, Erik; Brunsell, Per; Menmuir, Sheena; Drake, James

    2011-10-01

    The penetration of resonant magnetic perturbations (RMP) can be screened by plasma flow and the understanding of this phenomenon is important for ELM mitigation techniques. This work studies the screening effect in EXTRAP T2R. EXTRAP T2R is equipped with a feedback system able to suppress all error fields and to produce one or more external perturbations in a controlled fashion. The EXTRAP T2R feedback system is used to generate a RMP that interacts with the dynamics of its corresponding tearing mode (TM). The level of RMP penetration is quantified by analyzing the RMP effect on the TM amplitude and velocity. To study the screening effect, the flow is changed by applying a second perturbation that is non resonant (non-RMP). This produces the flow reduction without perturbing significantly the other parameters. By modifying the amplitude of the non-RMP, an experimental study of the flow effect on the RMP penetration is performed. Experimental results are compared with the model described in [Fitzpatrick R et al., Phys. Plasmas 8, 4489 (2001)].

  5. Renal blood flow, early distal sodium, and plasma renin concentrations during osmotic diuresis

    DEFF Research Database (Denmark)

    Leyssac, P P; Holstein-Rathlou, N H; Skøtt, O

    2000-01-01

    .6 mmHg. Urine flow increased 10-fold, and sodium excretion increased by 177%. Plasma renin concentration (PRC) increased by 58%. Renal blood flow and glomerular filtration rate decreased, however end-proximal flow remained unchanged. After a similar volume of hypotonic glucose (152 mM), ED......(NaCl) increased by 3.6 mM, (P renal hemodynamics, urine flow, sodium excretion rate, or PRC. Infusion of 300 micromol NaCl in a smaller volume caused ED(NaCl) to increase by 6.4 mM without significant changes in PRC. Urine flow and sodium excretion increased significantly...

  6. High speed photography of the plasma flow and the projectiles in the T.U.M. hypervelocity accelerator

    International Nuclear Information System (INIS)

    Igenbergs, E.; Kuczera, H.; Schroeder, B.

    1979-01-01

    The hypervelocity accelerator at the Technische Universitaet Muenchen, FRG, accelerates small projectiles (0.1 to 1.0 mm diameter) to velocities around 20 km/s. The photographic equipment consists of two Cordin single-frame image converter cameras and one TRW image converter camera with streak units and multiple-frame units. They are used for plasma flow diagnostics and the measurement of the position and the velocity of the projectiles. The single-frame cameras are triggered with a Laser light bar and the photographic measurement of the projectile velocity will be compared with Doppler-Radar. (author)

  7. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F

    1996-01-01

    Renal blood flow (RBF) was measured in 9 patients with chronic impaired kidney function using MR velocity mapping and compared to PAH clearance and 99mTc-DTPA scintigraphy. An image plane suitable for flow measurement perpendicular to the renal arteries was chosen from 2-dimensional MR angiography....... MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated...... by 99mTc-DTPA scintigraphy. A reduction of RBF was found, and there was a significant correlation between PAH clearance multiplied by 1/(1-hematocrit) and RBF determined by MR velocity mapping. Furthermore, a significant correlation between the distribution of renal function and the percent distribution...

  8. Measuring methods for the TFR plasma diagnostics

    International Nuclear Information System (INIS)

    Etievant, C.

    1975-02-01

    The measuring methods in operation or still under development for the diagnostics of the TFR plasma parameters (ion and electron temperatures, electron density, current density are reviewed, the diagnostics of the electrical behavior of the discharge, the neutral gas densities, the impurities and the parameters of the plasma turbulence being also investigated. Actual works are principally devoted to: improving ion temperature measurements by the possible use of the Doppler effect or infra-red incoherent scattering; improving n(e) and T(e) measurement by Thomson scattering; measuring the poloidal field and current density; measuring impurities by X and UV spectroscopy and measuring instabilities and turbulence [fr

  9. Plasma flow during the brightening of proton aurora in the cusp

    DEFF Research Database (Denmark)

    Taguchi, S.; Hosokawa, K.; Suzuki, S.

    2010-01-01

    On the basis of simultaneous observations from the Super Dual Auroral Radar Network (SuperDARN), the far ultraviolet instrument on the IMAGE spacecraft, and a magnetometer installed on the east coast of Greenland, we present the characteristics of plasma flow during a westward moving proton auror...... to the traveling bulge at the polar cap boundary, which is the footprint of a flux transfer event, and imply that the preexisting vortical flow may be intensified when it becomes inflow to the bulge....

  10. Nonlinear mechanism for the suppression of error field magnetic islands by plasma flow

    International Nuclear Information System (INIS)

    Parker, R.D.

    1992-01-01

    Non-axisymmetric magnetic field perturbations generated, for example, by errors in the alignment of the field coils are known to lead to reduced confinement in a tokamak. By inducing the formation of small, stationary, magnetic islands on all rational surfaces they can enhance radial transport and under certain circumstances interact with MHD instabilities to trigger the onset of locked modes leading, in some cases, to disruption of the plasma discharge. Given the stationary nature of the error field islands it is natural to consider whether they can be reduced significantly by the viscous drag of a sheared flow resulting from a bulk rotation of the plasma. In this paper, we examine this interaction by modelling the nonlinear growth and saturation of force-reconnected magnetic islands driven by a corrugated boundary in a slab plasma with an initially uniform flow. A systematic parameter study is made of the time asymptotic steady state. (author) 3 figs., 5 refs

  11. Plasma-cavity ringdown spectroscopy for analytical measurement: Progress and prospectives

    Science.gov (United States)

    Zhang, Sida; Liu, Wei; Zhang, Xiaohe; Duan, Yixiang

    2013-07-01

    Plasma-cavity ringdown spectroscopy is a powerful absorption technique for analytical measurement. It combines the inherent advantages of high sensitivity, absolute measurement, and relative insensitivity to light source intensity fluctuations of the cavity ringdown technique with use of plasma as an atomization/ionization source. In this review, we briefly describe the background and principles of plasma-cavity ringdown spectroscopy(CRDS) technology, the instrumental components, and various applications. The significant developments of the plasma sources, lasers, and cavity optics are illustrated. Analytical applications of plasma-CRDS for elemental detection and isotopic measurement in atomic spectrometry are outlined in this review. Plasma-CRDS is shown to have a promising future for various analytical applications, while some further efforts are still needed in fields such as cavity design, plasma source design, instrumental improvement and integration, as well as potential applications in radical and molecular measurements.

  12. Temperature measurement in low pressure plasmas. Temperaturmessungen im Niederdruckplasma

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbauer, K.A.; Wilting, H.; Schramm, G. (Duesseldorf Univ. (Germany, F.R.). Abt. fuer Histologie und Embryologie)

    1989-11-01

    The present work discusses the influence of various parameters on the substrate temperature in a low pressure plasma. The measurement method chosen utilized Signotherm (Merck) temperature sensors embedded in silicon between two glass substrates. All measurements were made in a 200 G Plasma Processor from Technics Plasma GmbH. The substrate temperature is dependent on the process time, the RF power, the process gas and the position in the chamber. The substrate temperature increases with increasing process time and increasing power. Due to the location of the microwave port from the magnetron to the chamber, the substrate temperature is highest in the center of the chamber. Measurements performed in an air plasma yielded higher results than in an oxygen plasma. (orig.).

  13. A key inactivation factor of HeLa cell viability by a plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Takehiko; Yokoyama, Mayo [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Johkura, Kohei, E-mail: sato@ifs.tohoku.ac.jp [Department of Histology and Embryology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621 (Japan)

    2011-09-21

    Recently, a plasma flow has been applied to medical treatment using effects of various kinds of stimuli such as chemical species, charged particles, heat, light, shock wave and electric fields. Among them, the chemical species are known to cause an inactivation of cell viability. However, the mechanisms and key factors of this event are not yet clear. In this study, we focused on the effect of H{sub 2}O{sub 2} in plasma-treated culture medium because it is generated in the culture medium and it is also chemically stable compared with free radicals generated by the plasma flow. To elucidate the significance of H{sub 2}O{sub 2}, we assessed the differences in the effects of plasma-treated medium and H{sub 2}O{sub 2}-added medium against inactivation of HeLa cell viability. These two media showed comparable effects on HeLa cells in terms of the survival ratios, morphological features of damage processes, permeations of H{sub 2}O{sub 2} into the cells, response to H{sub 2}O{sub 2} decomposition by catalase and comprehensive gene expression. The results supported that among chemical species generated in a plasma-treated culture medium, H{sub 2}O{sub 2} is one of the main factors responsible for inactivation of HeLa cell viability. (fast track communication)

  14. HANARO core channel flow-rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Heon Il; Chae, Hee Tae; Im, Don Soon; Kim, Seon Duk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    HANARO core consists of 23 hexagonal flow tubes and 16 cylindrical flow tubes. To get the core flow distribution, we used 6 flow-rate measuring dummy fuel assemblies (instrumented dummy fuel assemblies). The differential pressures were measured and converted to flow-rates using the predetermined relationship between AP and flow-rate for each instrumented dummy fuel assemblies. The flow-rate for the cylindrical flow channels shows +-7% relative errors and that for the hexagonal flow channels shows +-3.5% relative errors. Generally the flow-rates of outer core channels show smaller values compared to those of inner core. The channels near to the core inlet pipe and outlet pipes also show somewhat lower flow-rates. For the lower flow channels, the thermal margin was checked by considering complete linear power histories. From the experimental results, the gap flow-rate was estimated to be 49.4 kg/s (cf. design flow of 50 kg/s). 15 tabs., 9 figs., 10 refs. (Author) .new.

  15. Effect of disodium cromoglycate (DSCG) and antihistamines on postirradiation cerebral blood flow and plasma levels of histamine and neurotensin

    International Nuclear Information System (INIS)

    Cockerham, L.G.; Pautler, E.L.; Carraway, R.E.; Cochrane, D.E.; Hampton, J.D.

    1988-01-01

    In an attempt to elucidate mechanisms underlying the irradiation-induced decrease in regional cerebral blood flow (rCBF) in primates, hippocampal and visual cortical blood flows of rhesus monkeys were measured by hydrogen clearance, before and after exposure to 100 Gy, whole-body, gamma irradiation. Systemic blood pressures were monitored simultaneously. Systemic arterial plasma histamine and neurotensin levels were determined preirradiation and postirradiation. Compared to control animals, the irradiated monkeys exhibited an abrupt decline in systemic blood pressure to 23% of the preirradiation level within 10 min postirradiation, falling to 12% by 60 min. A decrease in hippocampal blood flow to 32% of the preirradiation level was noted at 10 min postirradiation, followed by a slight recovery to 43% at 30 min and a decline to 23% by 60 min. The cortical blood flow for the same animals showed a steady decrease to 29% of the preirradiation levels by 60 min postirradiation. Animals given the mast cell stabilizer disodium cromoglycate and the antihistamines mepyramine and cimetidine before irradiation did not exhibit an abrupt decline in blood pressure but displayed a gradual decrease to a level 33% below preirradiation levels by 60 min postirradiation. Also, the treated, irradiated monkeys displayed rCBF values that were not significantly different from the nonirradiated controls. The plasma neurotensin levels in the irradiated animals, treated and untreated, indicated a nonsignificant postirradiation increase above control levels. However, the postirradiation plasma histamine levels in both irradiated groups showed an increase of approximately 1600% above the preirradiation levels and the postirradiation control levels

  16. Nonlinear inertial Alfven waves in plasmas with sheared magnetic field and flow

    International Nuclear Information System (INIS)

    Chen Yinhua; Wang Ge; Tan Liwei

    2004-01-01

    Nonlinear equations describing inertial Alfven waves in plasmas with sheared magnetic field and flow are derived. For some specific parameters chosen, authors have found a new type of electromagnetic coherent structures in the tripolar vortex-like form

  17. Investigation of electron and ion flows in the microsecond plasma opening switch on the terawatt power level

    International Nuclear Information System (INIS)

    Bastrikov, A.N.; Bugaev, S.P.; Volkov, A.M.; Kim, A.A.; Kovalchuk, B.M.; Kokshener, V.M.; Yakovlev, V.A.; Bystritskii, V.M.; Grigoriev, S.V.; Krasik, Ya.E.

    1989-01-01

    The results of an investigation of ion and electron flows in the coaxial microsecond plasma opening switch (POS) at generator GIT-4 are given. The 1 mks front duration POS with outer and inner electrodes of 210 mm and 75 mm diameters respectively switched 1 MA pulse during 0.1 mks to the short circuited coaxial line with the same diameters and 120 cm of length. The polarity of the inner electrode was negative. The plasma of the POS was injected from outer electrode by 32 plasma guns of capillary type. The typical POS voltage was 0.9-1.2 MV. The calculated energy losses in the POS during the switching phase reached (0.1-0.15) MJ. The calorimetric measurements of the energy dissipated on both electrodes gave the same value. The location and distribution of the head absorbed along the POS electrodes were determined

  18. Soft Probes of the Quark-Gluon Plasma in ATLAS

    CERN Document Server

    Wozniak, K W; The ATLAS collaboration

    2014-01-01

    Measurements of low-$p_{_{\\rm T}}$ ($<$ 5 GeV) particles in Pb+Pb collisions at the LHC provide valuable insight in the production and evolution of the quark-gluon plasma. In particular, measurements of the elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS makes it possible to measure flow event-by-event and to determine the correlations between different event planes and different flow harmonics.

  19. Final Technical Report: Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Eugenio

    2014-05-02

    The strong coupling between the different physical variables involved in the plasma transport phenomenon and the high complexity of its dynamics call for a model-based, multivariable approach to profile control where those predictive models could be exploited. The overall objective of this project has been to extend the existing body of work by investigating numerically and experimentally active control of unstable fluctuations, including fully developed turbulence and the associated cross-field particle transport, via manipulation of flow profiles in a magnetized laboratory plasma device. Fluctuations and particle transport can be monitored by an array of electrostatic probes, and Ex B flow profiles can be controlled via a set of biased concentric ring electrodes that terminate the plasma column. The goals of the proposed research have been threefold: i- to develop a predictive code to simulate plasma transport in the linear HELCAT (HELicon-CAThode) plasma device at the University of New Mexico (UNM), where the experimental component of the proposed research has been carried out; ii- to establish the feasibility of using advanced model-based control algorithms to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles, iii- to investigate the fundamental nonlinear dynamics of turbulence and transport physics. Lehigh University (LU), including Prof. Eugenio Schuster and one full-time graduate student, has been primarily responsible for control-oriented modeling and model-based control design. Undergraduate students have also participated in this project through the National Science Foundation Research Experience for Undergraduate (REU) program. The main goal of the LU Plasma Control Group has been to study the feasibility of controlling turbulence-driven transport by shaping the radial poloidal flow profile (i.e., by controlling flow shear) via biased concentric ring electrodes.

  20. Deposition probe measurements of impurities injected into a tokamak plasma

    International Nuclear Information System (INIS)

    Hildebrandt, D.; Grote, H.; Herrmann, A.

    1985-01-01

    Impurity confinement behaviour has been studied by using a deposition probe in conjunction with pellet injection. Generally, an exponential decay of the impurity efflux and nearly symmetric ion/electron side toroidal flows have been observed. During phases of strong plasma disturbances, asymmetric flow is seen, indicative of edge transport and prompt recycling from local sources. The application of ECRH may cause such disturbances. (author)

  1. Dynamics, OH distributions and UV emission of a gliding arc at various flow-rates investigated by optical measurements

    DEFF Research Database (Denmark)

    Zhu, Jiajian; Sun, Zhiwei; Li, Zhongshan

    2014-01-01

    -state OH were investigated using planar laser-induced fluorescence. The results show that the shape, height, intensity and thickness of ground-state OH distribution vary significantly with air flow rates. Finally, UV emission of the gliding arc is measured using optical emission spectroscopy......We demonstrate a plasma discharge which is generated between two diverging electrodes and extended into a gliding arc in non-equilibrium condition by an air flow at atmospheric pressure. Effects of the air flow rates on the dynamics, ground-state OH distributions and spectral characterization of UV...

  2. Microwave interferometry of PEOS plasma sources

    International Nuclear Information System (INIS)

    Weber, B.V.; Commisso, R.J.; Goodrich, P.J.; Hinshelwood, D.D.; Neri, J.M.

    1988-01-01

    A 70 GHz microwave interferometer is used to measure the electron density for various configurations of sources used in plasma erosion opening switch (PEOS) experiments. The interferometer is a phase quadrature system, so the density can be measured as a function of time without ambiguity. Measurements have been made for carbon guns and flashboards driven by a .6 μF. 25 kV capacitor. The plasma density from a gun rises to its peak value in about 10 μs. Then decays in the next 40 μs. A metal screen placed between the gun and the microwave beam attenuates the plasma density by a factor greater than the geometrical transparency of the screen. Density measurements as a function of distance from the gun are analyzed to give the plasma spatial dependence, and the particle flux density and flow velocity are calculated from the continuity equation. Density values used to model previous PEOS experiments are comparable to the values measured here. The flashboard sources produce a denser, faster plasma that is more difficult to diagnose with the interferometer than the gun plasma because of refractive bending of the microwave beam. Reducing the plasma length reduces the refractive bending enough that some measurements are possible. Direct comparison with Gamble II PEOS experiments that used these flashboard sources may not be possible at this frequency because of refraction, but estimates based on measurements at larger distances give reasonable agreement with values used to model these experiments. Other measurements that will be presented include the effects of plasma flow against metal walls, effects of changing the driving current waveform, measurements made in actual experimental configurations and comparisons with Faraday cup and electric probe measurements

  3. Operational features and air plasma characteristics of a thermal plasma torch with hollow electrodes

    International Nuclear Information System (INIS)

    Hur, Min; Kim, Keun Su; Hong, Sang Hee

    2003-01-01

    The operational features and thermal plasma characteristics of a plasma torch with hollow electrodes are investigated based on their dependence on input current, gas flow rate and electrode diameter when air is used as a plasma gas. A plasma torch with a hollow cathode and anode has been designed and fabricated, and the arc voltages and thermal efficiencies are measured from its discharge. The newly modified similarity criteria are derived from the measured data related to torch performances. From the fact that these criteria successfully describe both the arc voltage and thermal efficiency behaviour of the torch, depending on its operating and geometrical parameters, it is proved that they can be usefully applied to the design and operation of high power torches. For the numerical modelling of the interior region of the torch, a cold flow analysis is employed along with a simplified balance equation of the Lorentz and gas dynamic drag forces in order to determine a cathode spot position on the cathode surface. The validity of this method is confirmed by comparison of the calculated and measured net powers. As a practically useful result of this analysis, carried out through this numerical and experimental work, it is suggested that low input current, high gas flow rate and relatively large electrode diameter are more favourable as appropriate operating conditions of the torch for the efficient treatment of hazardous organic wastes

  4. Gas and particle velocity measurements in an induction plasma

    International Nuclear Information System (INIS)

    Lesinski, J.; Gagne, R.; Boulos, M.I.

    1981-08-01

    Laser doppler anemometry was used for the measurements of the plasma and particle velocity profiles in the coil region of an inductively coupled plasma. Results are reported for a 50 mm ID induction torch operated at atmospheric pressure with argon as the plasma gas. The oscillator frequency was 3 MHz and the power in the coil was varied between 4.6 and 10.5 kW. The gas velocity measurements were made using a fine carbon powder as a tracer (dp approx. = 1 μm). Measurements were also made with larger silicon particles (dp = 33 μm and sigma = 13 μm) centrally injected in the plasma under different operating conditions

  5. Dynamic gas flow during plasma operation in TMX-U

    International Nuclear Information System (INIS)

    Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

    1982-01-01

    Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73 0 Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation

  6. Laser produced plasma density measurement by Mach-Zehnder interferometry

    International Nuclear Information System (INIS)

    Vaziri, A.; Kohanzadeh, Y.; Mosavi, R.K.

    1976-06-01

    This report describes an optical interferometric method of measuring the refractive index of the laser-produced plasma, giving estimates of its electron density. The plasma is produced by the interaction of a high power pulsed CO 2 laser beam with a solid target in the vacuum. The time varying plasma has a transient electron density. This transient electron density gives rise to a changing plasma refractive index. A Mach-Zehnder ruby laser interferometer is used to measure this refractive index change

  7. Coherent structures induced by dielectric barrier discharge plasma actuator

    Science.gov (United States)

    Zhang, Xin; Li, Huaxing; Choi, Kwing So; Song, Longfei

    2017-11-01

    The structures of a flow field induced by a plasma actuator were investigated experimentally in quiescent air using high-speed Particle Image Velocimetry (PIV) technology. The motivation behind was to figure out the flow control mechanism of the plasma technique. A symmetrical Dielectric Barrier Discharge (DBD) plasma actuator was mounted on the suction side of the SC (2)-0714 supercritical airfoil. The results demonstrated that the plasma jet had some coherent structures in the separated shear layer and these structures were linked to a dominant frequency of f0 = 39 Hz when the peak-to-peak voltage of plasma actuator was 9.8 kV. The high speed PIV measurement of the induced airflow suggested that the plasma actuator could excite the flow instabilities which lead to production of the roll-up vortex. Analysis of transient results indicated that the roll-up vortices had the process of formation, movement, merging and breakdown. This could promote the entrainment effect of plasma actuator between the outside airflow and boundary layer flow, which is very important for flow control applications.

  8. Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis

    Science.gov (United States)

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

    We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

  9. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    Science.gov (United States)

    Zanáška, M.; Adámek, J.; Peterka, M.; Kudrna, P.; Tichý, M.

    2015-03-01

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents Isat-/Isat+ to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.

  10. Start-up assist by magnetized plasma flow injection in TPE-RX reversed-field pinch

    Energy Technology Data Exchange (ETDEWEB)

    Asai, T. [College of Science and Technology, Nihon University, 1-8 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan)]. E-mail: asai@phys.cst.nihon-u.ac.jp; Nagata, M. [Graduate School of Engineering, University of Hyogo, Himeji (Japan); Koguchi, H. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan); Hirano, Y. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan); Sakakita, H. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan); Yambe, K. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan); Kiyama, S. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan)

    2006-11-15

    A reversed-field pinch (RFP) start-up assisted by a magnetized plasma flow injection was demonstrated for the first time on a TPE-RX machine. This sequence of experiments aimed to establish a new method of ionization, gas-fill and helicity injection in the start-up phase of an RFP. In this start-up method, magnetized and well-ionized plasma is formed by a magnetized coaxial plasma gun and injected into the torus chamber as an initial pre-ionized plasma for RFP formation. In the initial experiments, attenuated density pump-out and comparatively slow decay of the toroidal flux and plasma current were observed as evidence of its being an effective start-up method.

  11. Collisionless coupling of a high- β expansion to an ambient, magnetized plasma. II. Experimental fields and measured momentum coupling

    Science.gov (United States)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2018-04-01

    The momentum coupled to a magnetized, ambient argon plasma from a high- β, laser-produced carbon plasma is examined in a collisionless, weakly coupled limit. The total electric field was measured by separately examining the induced component associated with the rapidly changing magnetic field of the high- β (kinetic β˜106), expanding plasma and the electrostatic component due to polarization of the expansion. Their temporal and spatial structures are discussed and their effect on the ambient argon plasma (thermal β˜10-2) is confirmed with a laser-induced fluorescence diagnostic, which directly probed the argon ion velocity distribution function. For the given experimental conditions, the electrostatic field is shown to dominate the interaction between the high- β expansion and the ambient plasma. Specifically, the expanding plasma couples energy and momentum into the ambient plasma by pulling ions inward against the flow direction.

  12. Transverse baryon flow as possible evidence for a quark-gluon-plasma phase

    International Nuclear Information System (INIS)

    Levai, P.; Mueller, B.

    1991-01-01

    In order to investigate the coupling between collective flow of nucleons and pions in hot pion-dominated hadronic matter, we calculate the pion-nucleon drag coefficient in linearized transport theory. We find that the characteristic time for flow equalization is longer than the time scale of the expansion of a hardonic fireball created in high-energy collisions. The analysis of transverse-momentum data from p+bar p collisions at √s =1.8 TeV reveals the same flow velocity for mesons and antinucleons. We argue that this may be evidence for the formation of a quark-gluon plasma in these collisions

  13. Duality of the magnetic flux tube and electric current descriptions magnetospheric plasma and energy flow

    International Nuclear Information System (INIS)

    Atkinson, G.

    1981-01-01

    The duality between electric current and magnetic flux tubes is outlined for the magnetosphere. Magnetic flux tubes are regarded as fluid elements subjected to various stresses. Current closure then becomes the dual of stress balance, and Poynting vector energy flow a dual of J x E dissipation. The stresses acting on a flux tube are magnetic stresses, which correspond to currents at a distance, and plasma stresses, which correspond to local currents. The duality between current and stress is traced for ionospheric ion drag forces, solar wind stresses at the magnetopause, inertial effects, and the effects of energetic plasma on flux tubes. The stress balance and dual current systems are outlined for idealized magnetospheres of increasing complexity. For a simple magnetosphere with no convective flow, the balance stresses are solar wind pressure and neutral sheet plasma pressure. The corresponding current systems are the Chapman-Ferraro magnetopause currents and the magetotail current system. The introduction of convective flow introduces further stresses: ionospheric ion drag. Alfven layer shielding, and an imbalance in day-night magnetic stresses due to transport of flux tubes to the nightside by the solar wind. These stresses balance, and hence the corresponding additional currents (the ionospheric Pedersen current and the electrojets, the partial ring current, and two other current systems from the magnetopause and tail) must form a closed current system and do so by the region I and II field-aligned currents of Iijima and Potemra. The energy flow in the above models is described in terms of both Poynting vectors and the above current systems. Temporal variations examined are (1) an increase in dayside merging and/or nightside reconnection, (2) an increase in the energy density of plasma in the plasma sheet, (3) an increase in ionospheric conductivity, and (4) an increase in solar wind pressure

  14. Chemical and physical reactions under thermal plasmas conditions

    International Nuclear Information System (INIS)

    Fauchais, P.; Vardelle, A.; Vardelle, M.; Coudert, J.F.

    1987-01-01

    Basic understanding of the involved phenomena lags far behind industrial development that requires now a better knowledge of the phenomena to achieve a better control of the process allowing to improve the quality of the products. Thus the authors try to precise what is their actual knowledge in the fields of: plasma generators design; plasma flow models with the following key points: laminar or turbulent flow, heat transfer to walls, 2D or 3D models, non equilibrium effects, mixing problems when chemical reactions are to be taken into account with very fast kinetics, electrode regions, data for transport properties and kinetic rates; nucleation problems; plasma flow characteristics measurements: temperature or temperatures and population of excited states (automatized emission spectroscopy, LIF, CARS) as well as flow velocity (LDA with small particles, Doppler effects...); plasma and particles momentum and heat transfer either with models taking into account particles size and injection velocity distributions, heat propagation, vaporization, Kundsen effect, turbulences ... or with measurements: particles velocity and flux distributions (Laser Anemometry) as well as surface temperature distributions (two colour pyrometry in flight statistical or not)

  15. Comparisons of Force Measurement Methods for DBD Plasma Actuators in Quiescent Air

    Science.gov (United States)

    Hoskinson, Alan R.; Hershkowitz, Noah; Ashpis, David E.

    2009-01-01

    We have performed measurements of the force induced by both single (one electrode insulated) and double (both electrodes insulated) dielectric barrier discharge plasma actuators in quiescent air. We have shown that, for single barrier actuators with cylindrical exposed electrodes, as the electrode diameter decrease the force efficiencies increase much faster than a previously reported linear trend. This behavior has been experimentally verified using two different measurement techniques: stagnation probe measurements of the induced flow velocity and direct measurement of the force using an electronic balance. Actuators with rectangular cross-section exposed electrodes do not show the same rapid increase at small thicknesses. We have also shown that the induced force is independent of the material used for the exposed electrode. The same techniques have shown that the induced force of a double barrier actuator increases with decreasing narrow electrode diameter.

  16. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    Eck, van H.J.N.; Koppers, W.R.; Rooij, van G.J.; Goedheer, W.J.; Engeln, R.A.H.; Schram, D.C.; Lopes Cardozo, N.J.; Kleyn, A.W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial

  17. Triple-probe method applied to the direct display of plasma parameters in a supersonic flowing continuum plasma

    International Nuclear Information System (INIS)

    Ogram, G.L.; Chang, J.; Hobson, R.M.

    1979-01-01

    The calibration of electrostatic triple-probe voltage and current response in a supersonic continuum plasma has been carried out using a low-pressure shock tube. The electron temperature T/sub e/ and charge number density N/sub e/ are compared to probe voltage and current response, respectively, for a useful range of plasma parameters (1 13 13 is the nondimensional probe voltage). The dependence of probe response on Debye ratio R/sub p//lambda/sub D/ and various flow parameters was investigated. The probe voltage response was found to depend significantly on the Debye ratio. Expressions for electron temperature determination by triple probe are presented

  18. Plasma profiles and flows in the high-field side scrape-off layer in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Smick, N. [MIT Plasma Science and Fusion Center, NW17-170, 175 Albany St., Cambridge, MA 02139 (United States)]. E-mail: nsmick@mit.edu; LaBombard, B. [MIT Plasma Science and Fusion Center, NW17-170, 175 Albany St., Cambridge, MA 02139 (United States); Pitcher, C.S. [132 Bowood Ave., Toronto, M4N1Y5 (Canada)

    2005-03-01

    A novel, magnetically-driven swing probe was recently installed near the midplane on the high-field side SOL in Alcator C-Mod. The probe collects plasma from co- and counter-current directions during its respective 0-90 deg and 90-180 deg of motion, thus providing profiles of density, electron temperature and plasma flow parallel to magnetic field lines (Mach number, M{sub parallel}) up to the separatrix. Results are reported from discharges with different magnetic topologies: lower single-null, upper single-null, and double-null. In single-null, a strong parallel flow (vertical bar M{sub parallel} vertical bar {approx} 1) is detected, which is always directed from the low- to high-field SOL. In double-null discharges, e-folding lengths in the high-field SOL are a factor of {approx}4 shorter than the low-field SOL. Thus, plasma appears to 'fill-in' the high-field SOL in single-null plasmas, not by cross-field transport but by parallel flow from the low-field SOL - a picture consistent with a very strong ballooning-like component to the cross-field transport.

  19. Plasma end-loss studies on Scylla I-C

    International Nuclear Information System (INIS)

    McKenna, K.F.; York, T.M.

    1976-08-01

    The end-loss process in the collision dominated Scylla I-C plasma has been investigated with a local pressure sensitive diagnostic, integrated density measurement and axially arrayed diamagnetic loop probes. The development of a plasma loss orifice, well within the theta-pinch coil, has been identified. The magnitude of the observed orifice is found to be in excellent agreement with that predicted from collisional MHD theories. The axially flowing plasma is well confined until it flows through the loss orifice. After passing through the orifice, rapid axial expansion is observed. An indication of the existence of inward traveling rarefaction waves has been observed from the plasma midplane temperature data; an abrupt decrease in the plasma temperature at t approximately equal to 6.5 μs corresponds to the predicted time of arrival of rarefaction waves at the coil midplane. The plasma loss rate derived from the pressure data indicates an initial period (t 4 μs) of gradual decay in the loss rate. This initial period of high loss rate is predicted from the MHD flow theories when the measured, time dependent plasma parameters are substituted into the analytical models. The loss rate determined from the end-on interferograms does not respond to the detailed structure of the plasma loss process

  20. Flow and correlation phenomena measurements in pp, pPb and PbPb collisions at CMS

    CERN Document Server

    Padula, Sandra

    2017-01-01

    The quark-gluon plasma created in high energy collisions of large nuclei exhibits strong anisotropic collective behavior as a nearly perfect fluid, flowing with little frictional resistance or viscosity. It has been investigated extensively over the past years employing two or more particle correlations. An overview of collective flow and particle correlation measurements at CMS as a function of transverse momentum, pseudorapidity, event multiplicity, for both charged hadrons or identified particles will be presented. These results are compared among pp, pPb and PbPb systems and several aspects of their intriguing similarities are discussed. 

  1. Flow and correlation phenomena measurements in pp, pPb and PbPb collisions at CMS

    Directory of Open Access Journals (Sweden)

    S. Padula Sandra

    2018-01-01

    Full Text Available The quark-gluon plasma created in high energy collisions of large nuclei exhibits strong anisotropic collective behavior as a nearly perfect fluid, flowing with little frictional resistance or viscosity. It has been investigated extensively over the past years employing two or more particle correlations. An overview of collective flow and particle correlation measurements at CMS as a function of transverse momentum, pseudorapidity, event multiplicity, for both charged hadrons or identified particles will be presented. These results are compared among pp, pPb and PbPb systems and several aspects of their intriguing similarities are discussed.

  2. Soft probes of the quark gluon plasma in ATLAS

    CERN Document Server

    Wozniak, K W; The ATLAS collaboration

    2014-01-01

    Measurements of low-$p_{T}$ (< 5 GeV) particle production have provided valuable insight on the production and evolution of the quark-gluon plasma in Pb+Pb collisions at the LHC. In particular, measurements of elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS have made it possible to measure flow event-by-event and to determine the correlations between different harmonics. Recent measurements of low-$p_{T}$ particle production and multi-particle correlations in proton-lead collisions have shown features similar to the collective flow observed in Pb+Pb collisions. Results will be presented from a variety of single and multi-particle measurements in Pb+Pb and proton-Pb collisions that probe the collective dynamics of the quark gluon plasma and possibly provide evidence for ...

  3. A reexamination of plasma measurements from the Mariner 5 Venus encounter

    Science.gov (United States)

    Shefer, R. E.; Lazarus, A. J.; Bridge, H. S.

    1979-01-01

    Mariner 5 plasma data from the Venus encounter have been analyzed with twice the time resolution of the original analysis of Bridge et al. (1967). The velocity distribution function for each spectrum is used to determine more precisely the locations of boundaries and characteristic flow parameters in the interaction region around the planet. A new region is identified in the flow located between magnetosheathlike plasma inside the shock front and an interior low-flux region near the geometrical shadow of the planet. The region is characterized by a wide velocity distribution function and a decrease in ion flux. Using the highest time resolution magnetic field data, it is proposed that rapid magnetic field fluctuations in this region may result in an artificial broadening of the distribution function. It is concluded that very high time resolution is required in future experiments in order to determine the true nature of the plasma in this region.

  4. Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

    Science.gov (United States)

    Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

  5. Evaluation of compatibility of flowing liquid lithium curtain for blanket with core plasma in fusion reactors

    International Nuclear Information System (INIS)

    Deng Baiquan; Huang Jinhua; Peng Lilin; Yan Jiancheng

    2003-01-01

    A global model analysis of the compatibility of flowing liquid lithium curtain for blanket with core plasma has been performed. The relationships between the surface temperature of lithium curtain and mean effective plasma charges, fuel dilution and produced fusion power have been obtained. Results show that under normal circumstances, the evaporation of liquid lithium does not affect Z eff seriously, but affects fuel dilution and fusion power sensitively. The authors have investigated the relationships between the flow velocity of liquid lithium and its surface temperature rise based on the conditions of the option II of the fusion experimental breeder (FEB-E) design with reversed shear configuration and fairly high power density. The authors concluded that the effects of evaporation from liquid lithium curtain for FEB-E on plasma are negligible even if the flow velocity of liquid lithium is as low as 0.5 m·s -1 . Finally, the sputtering yield of liquid lithium saturated by hydrogen isotopes is briefly discussed

  6. Bifurcation of plasma cylinder equilibrium into a stationary helical flow with magnetic islands

    International Nuclear Information System (INIS)

    Gubarev, V.F.; Dmitrenko, A.G.; Fesenko, A.I.

    1985-01-01

    Introduction of the low-hydrodynamic viscosity into the system of nonlinear MHD-equations enabled to use the bifurcation theory for the investigation into nonlinear phenomena connected with a tearing mode. The existance of a stable stationary helical flow with magnetic islands in the vicinity of a neutral curve is established. Fransfer from an axisymmetric equilibrium of a plasma cylinder to a helical one takes place only under soft conditions at both sides of the neutral curve. This result confirms the fact that the tearing mode, actually, is not an instability and may be con sidered only as a reason of formation of equilibrium with splitted magnetic surfaces. Really, changing the q 0 parameter (q 0 is the value proportional to a value of stability margin) at the plasma filament boundary a plasma equilibrium is attained corresponding to a stable branch of the bifurcation curve. In this case, a stable branch of the bifurcation curve corresponds to a helical stationary flow with magnetic islands in the instabwility region determined from the linear theory

  7. Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

    Energy Technology Data Exchange (ETDEWEB)

    Adam B. Sefkow and Samuel A. Cohen

    2009-04-09

    Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ~ 200-300 λD,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.

  8. Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

    International Nuclear Information System (INIS)

    Sefkow, Adam B.; Cohen, Samuel A.

    2009-01-01

    Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ∼ 200-300 λ D,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength

  9. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    Science.gov (United States)

    Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

    2014-09-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

  10. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    International Nuclear Information System (INIS)

    Yeh, Chia-Hsien; Hung, Chia-Wei; Lin, Yu-Cheng; Wu, Chun-Han

    2014-01-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood. (paper)

  11. Unsteady flow measurements in centrifugal compressors

    International Nuclear Information System (INIS)

    Bammert, K.; Mobarak, A.; Rautenberg, M.

    1976-01-01

    Centrifugal compressors and blowers are often used for recycling the coolant gas in gas-cooled reactors. To achieve the required high pressure ratios, highly loaded centrifugal compressors are built. The paper deals with unsteady flow measurements on highly loaded centrifugal impellers. Measurements of the approaching flow have been done with hot wires. The method of measurement enabled us to get the velocity distribution across the pitch ahead of the inducer. The static pressure signals along the shroud line has been discussed on the basis of some theoretical considerations. Accordingly the form of flow in the impeller and the wave flow or separation zones in the impeller can now be better interpreted. The importance of the unsteady nature of the relative flow, especially at impeller exit, is clearly demonstrated. Measurements with high responsive total pressure probes in the vicinity of impeller exit and the subsequent calculations have shown, that the instantaneous energy transfer at a certain point after the impeller may differ by more than 30% from the Euler work. Lastly, unsteady pressure measurements along the shroud line have been performed during surge and rotating stall. The surge signal have been analyzed in more detail and the mechanism of flow rupture and pressure recovery during a surge cycle is thoroughly discussed. (orig.) [de

  12. 40 CFR 89.414 - Air flow measurement specifications.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Air flow measurement specifications... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... incorporates devices that affect the air flow measurement (such as air bleeds) that result in understated...

  13. A measurement device for electromagnetic flow tomography

    Science.gov (United States)

    Vauhkonen, M.; Hänninen, A.; Lehtikangas, O.

    2018-01-01

    Electromagnetic flow meters have succesfully been used in many industries to measure the mean flow velocity of conductive liquids. This technology works reliably in single phase flows with axisymmetric flow profiles but can be inaccurate with asymmetric flows, which are encountered, for example, in multiphase flows, pipe elbows and T-junctions. Some computational techniques and measurement devices with multiple excitation coils and measurement electrodes have recently been proposed to be used in cases of asymmetric flows. In earlier studies, we proposed a computational approach for electromagnetic flow tomography (EMFT) for estimating velocity fields utilizing several excitation coils and a set of measurement electrodes attached to the surface of the pipe. This approach has been shown to work well with simulated data but has not been tested extensively with real measurements. In this paper, an EMFT system with four excitation coils and 16 measurement electrodes is introduced. The system is capable of using both square wave and sinusoidal coil current excitations and all the coils can be excited individually, also enabling parallel excitations with multiple frequencies. The studies undertaken in the paper demonstrate that the proposed EMFT system, together with the earlier introduced velocity field reconstruction approach, is capable of producing reliable velocify field estimates in a laboratory environment with both axisymmetric and asymmetric single phase flows.

  14. Ion collection by a sphere in a flowing plasma: 2. non-zero Debye length

    International Nuclear Information System (INIS)

    Hutchinson, I H

    2003-01-01

    The spatial distribution of ion flux to a sphere in a flowing collisionless plasma is calculated using a particle-in-cell code SCEPTIC. The code is validated by comparing with prior stationary-plasma and approximate calculations. Comprehensive results are provided for ion temperatures 1 and 0.1 times the electron temperature, and for Debye length from 0.01 to 100 times the probe size. A remarkable qualitatively new result is obtained: over a range of Debye lengths from roughly 0.1 to 10 times the probe radius at T i = 0.1T e , the downstream side of the probe receives substantially higher flux density than the upstream side when the flow is subsonic. This unexpected reversal of the asymmetry reinforces the need for these fully self-consistent calculations, but renders the use of the flux ratio for Mach-probe purposes problematic, even for deriving the direction of the flow

  15. Modeling the Plasma Flow in the Inner Heliosheath with a Spatially Varying Compression Ratio

    Energy Technology Data Exchange (ETDEWEB)

    Nicolaou, G. [Swedish Institute of Space Physics, Kiruna (Sweden); Livadiotis, G. [Southwest Research Institute, San Antonio, Texas (United States)

    2017-03-20

    We examine a semi-analytical non-magnetic model of the termination shock location previously developed by Exarhos and Moussas. In their study, the plasma flow beyond the shock is considered incompressible and irrotational, thus the flow potential is analytically derived from the Laplace equation. Here we examine the characteristics of the downstream flow in the heliosheath in order to resolve several inconsistencies existing in the Exarhos and Moussas model. In particular, the model is modified in order to be consistent with the Rankine–Hugoniot jump conditions and the geometry of the termination shock. It is shown that a shock compression ratio varying along the latitude can lead to physically correct results. We describe the new model and present several simplified examples for a nearly spherical, strong termination shock. Under those simplifications, the upstream plasma is nearly adiabatic for large (∼100 AU) heliosheath thickness.

  16. Stabilisation of a three-dimensional boundary layer by base-flow manipulation using plasma actuators

    International Nuclear Information System (INIS)

    Dörr, P C; Kloker, M J

    2015-01-01

    The applicability of dielectric barrier discharge plasma actuators for controlling the crossflow-vortex-induced laminar breakdown in a three-dimensional swept-wing-type boundary-layer flow is investigated using direct numerical simulation. Similar to the classical application of suction at the wall the aim is to modify the quasi two-dimensional base flow and to weaken primary crossflow (CF) instability, mainly due to a reduction of the basic CF. Not only localised volumetric forcing by plasma actuators but also CF counter-blowing and spots with a moving wall are investigated to identify effective fundamental mechanisms. It is found that counter blowing always results in partial blockage of the flow and eventually increased CF velocity, whereas moving-wall spots can slightly reduce the CF and the amplitude of crossflow vortices. Using discrete volumetric forcing a significant attenuation even of finite-amplitude crossflow vortices and thus a distinct transition delay is achieved. (paper)

  17. Flow measurement at the aortic root

    DEFF Research Database (Denmark)

    Bertelsen, Litten; Svendsen, Jesper Hastrup; Køber, Lars

    2016-01-01

    during CMR and aortic stenosis were excluded from the analyses. Stroke volumes were measured volumetrically (SVref) from steady-state free precision short axis images covering the entire left ventricle, excluding the papillary muscles and including the left ventricular outflow tract. Flow sequences......BACKGROUND: Cardiovascular magnetic resonance (CMR) is considered the gold standard of cardiac volumetric measurements. Flow in the aortic root is often measured at the sinotubular junction, even though placing the slice just above valve level may be more precise. It is unknown how much flow...... theoretically be equal to flow measurements, SVV and SVST were compared to SVref. RESULTS: Initially, 152 patients were included. 22 were excluded because of arrhythmias during scans and 9 were excluded for aortic stenosis. Accordingly, data from 121 patients were analysed and of these 63 had visually evident...

  18. An Analysis of Ionospheric Thermal Ions Using a SIMION-based Forward Instrument Model: In Situ Observations of Vertical Thermal Ion Flows as Measured by the MICA Sounding Rocket

    Science.gov (United States)

    Fernandes, P. A.; Lynch, K. A.; Zettergren, M. D.; Hampton, D. L.; Fisher, L. E.; Powell, S. P.

    2013-12-01

    The MICA sounding rocket launched on 19 Feb. 2012 into several discrete, localized arcs in the wake of a westward traveling surge. In situ and ground-based observations provide a measured response of the ionosphere to preflight and localized auroral drivers. In this presentation we focus on in situ measurements of the thermal ion distribution. We observe thermal ions flowing both up and down the auroral field line, with upflows concentrated in Alfvénic and downward current regions. The in situ data are compared with recent ionospheric modeling efforts (Zettergren et al., this session) which show structured patterns of ion upflow and downflow consistent with these observations. In the low-energy thermal plasma regime, instrument response to the measured thermal ion population is very sensitive to the presence of the instrument. The plasma is shifted and accelerated in the frame of the instrument due to flows, ram, and acceleration through the payload sheath. The energies associated with these processes are large compared to the thermal energy. Rigorous quantitative analysis of the instrument response is necessary to extract the plasma properties which describe the full 3D distribution function at the instrument aperture. We introduce an instrument model, developed in the commercial software package SIMION, to characterize instrument response at low energies. The instrument model provides important insight into how we would modify our instrument for future missions, including fine-tuning parameters such as the analyzer sweep curve, the geometry factor, and the aperture size. We use the results from the instrument model to develop a forward model, from which we can extract anisotropic ion temperatures, flows, and density of the thermal plasma at the aperture. Because this plasma has transited a sheath to reach the aperture, we must account for the acceleration due to the sheath. Modeling of this complex sheath is being conducted by co-author Fisher, using a PIC code

  19. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    International Nuclear Information System (INIS)

    Zanáška, M.; Kudrna, P.; Tichý, M.; Adámek, J.; Peterka, M.

    2015-01-01

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents I sat − /I sat + to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa

  20. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zanáška, M.; Kudrna, P.; Tichý, M. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 12116 Prague 2 (Czech Republic); Adámek, J. [Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 18200 Prague 8 (Czech Republic); Peterka, M. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 12116 Prague 2 (Czech Republic); Institute of Plasma Physics AS CR, v.v.i., Za Slovankou 3, 18200 Prague 8 (Czech Republic)

    2015-03-15

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents I{sub sat}{sup −}/I{sub sat}{sup +} to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.

  1. Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-06-01

    Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

  2. Spectroscopic analysis applied to temperature measurement in plasmas

    International Nuclear Information System (INIS)

    Fieffe-Prevost, P.

    1978-01-01

    The plasma temperature is defined only if the plasma is in a state near thermodynamic equilibrium. This plasma state is analysed in detail and spectroscopic methods for measuring the temperature are discussed. As an application the hydrogen arc of the National Institute of Metrology of the Conservatoire National des Arts et Metiers (Paris) is briefly described [fr

  3. Measurements of plasma position in TJ-I Tokamak

    International Nuclear Information System (INIS)

    Qin, J.; Ascasibar, E.; Navarro, A.P.; Ochando, M.A.; Pastor, I.; Pedrosa, M.A.; Rodriguez, L.; Sanchez, J.; Team, TJ-I.

    1994-01-01

    This report presents the experimental measurements of plasma position in TJ-I tokamak by using small magnetic probes. The basis of method has been described in our previous work (1) in which the plasma current is considered as a filament current. The observed relations between the disruptive instabilities and plasma displacements are also show here. (Author) 7 refs

  4. Plasma position from ring current measurements in Extrap T1

    International Nuclear Information System (INIS)

    Brunsell, P.; Jin Li.

    1989-11-01

    The inductive coupling between the plasma and the four octupole field coils in the Extrap T1 device is utilized as a means of estimating the plasma position. The current in each octupole ring as well as the plasma current is measured by a Rogowski coil and the ring - plasma mutual inductance is then computed assuming axisymmetric plasma displacements. The obtained position is in agreement with internal magnetic probe measurements. The time - evolution of the plasma position for different external vertical and toroidal field strengths is studied. For the present discharge parameter a vertical field of about .008 T is found to give an almost radially stationary plasma. The results are compared with a simple equilibrium model

  5. Two-dimensional electron flow in pulsed power transmission lines and plasma opening switches

    International Nuclear Information System (INIS)

    Church, B.W.; Longcope, D.W.; Ng, C.K.; Sudan, R.N.

    1991-01-01

    The operation of magnetically insulated transmission lines (MITL) and the interruption of current in a plasma opening switch (POS) are determined by the physics of the electrons emitted by the cathode surface. A mathematical model describes the self-consistent two-dimensional flow of an electron fluid. A finite element code, FERUS, has been developed to solve the two equations which describe Poisson's and Ampere's law in two dimensions. The solutions from this code are obtained for parameters where the electron orbits are considerably modified by the self-magnetic field of the current. Next, the self-insulated electron flow in a MITL with a step change in cross-section is studied using a conventional two-dimensional fully electromagnetic particle-in-cell code, MASK. The equations governing two-dimensional quasi-static electron flow are solved numerically by a third technique which is suitable for predicting current interruption in a POS. The object of the study is to determine the critical load impedance, Z CL , required for current interruption for a given applied voltage, cathode voltage and plasma length. (author). 9 refs, 5 figs

  6. Supersonic flow with shock waves. Monte-Carlo calculations for low density plasma. I

    International Nuclear Information System (INIS)

    Almenara, E.; Hidalgo, M.; Saviron, J. M.

    1980-01-01

    This Report gives preliminary information about a Monte Carlo procedure to simulate supersonic flow past a body of a low density plasma in the transition regime. A computer program has been written for a UNIVAC 1108 machine to account for a plasma composed by neutral molecules and positive and negative ions. Different and rather general body geometries can be analyzed. Special attention is played to tho detached shock waves growth In front of the body. (Author) 30 refs

  7. Issues in measure-preserving three dimensional flow integrators: Self-adjointness, reversibility, and non-uniform time stepping

    International Nuclear Information System (INIS)

    Finn, John M.

    2015-01-01

    Properties of integration schemes for solenoidal fields in three dimensions are studied, with a focus on integrating magnetic field lines in a plasma using adaptive time stepping. It is shown that implicit midpoint (IM) and a scheme we call three-dimensional leapfrog (LF) can do a good job (in the sense of preserving KAM tori) of integrating fields that are reversible, or (for LF) have a “special divergence-free” (SDF) property. We review the notion of a self-adjoint scheme, showing that such schemes are at least second order accurate and can always be formed by composing an arbitrary scheme with its adjoint. We also review the concept of reversibility, showing that a reversible but not exactly volume-preserving scheme can lead to a fractal invariant measure in a chaotic region, although this property may not often be observable. We also show numerical results indicating that the IM and LF schemes can fail to preserve KAM tori when the reversibility property (and the SDF property for LF) of the field is broken. We discuss extensions to measure preserving flows, the integration of magnetic field lines in a plasma and the integration of rays for several plasma waves. The main new result of this paper relates to non-uniform time stepping for volume-preserving flows. We investigate two potential schemes, both based on the general method of Feng and Shang [Numer. Math. 71, 451 (1995)], in which the flow is integrated in split time steps, each Hamiltonian in two dimensions. The first scheme is an extension of the method of extended phase space, a well-proven method of symplectic integration with non-uniform time steps. This method is found not to work, and an explanation is given. The second method investigated is a method based on transformation to canonical variables for the two split-step Hamiltonian systems. This method, which is related to the method of non-canonical generating functions of Richardson and Finn [Plasma Phys. Controlled Fusion 54, 014004 (2012

  8. Image processing system for flow pattern measurements

    International Nuclear Information System (INIS)

    Ushijima, Satoru; Miyanaga, Yoichi; Takeda, Hirofumi

    1989-01-01

    This paper describes the development and application of an image processing system for measurements of flow patterns occuring in natural circulation water flows. In this method, the motions of particles scattered in the flow are visualized by a laser light slit and they are recorded on normal video tapes. These image data are converted to digital data with an image processor and then transfered to a large computer. The center points and pathlines of the particle images are numerically analized, and velocity vectors are obtained with these results. In this image processing system, velocity vectors in a vertical plane are measured simultaneously, so that the two dimensional behaviors of various eddies, with low velocity and complicated flow patterns usually observed in natural circulation flows, can be determined almost quantitatively. The measured flow patterns, which were obtained from natural circulation flow experiments, agreed with photographs of the particle movements, and the validity of this measuring system was confirmed in this study. (author)

  9. Microturbulence and Flow Shear in High-performance JET ITB Plasma; TOPICAL

    International Nuclear Information System (INIS)

    R.V. Budny; A. Andre; A. Bicoulet; C. Challis; G.D. Conway; W. Dorland; D.R. Ernst; T.S. Hahm; T.C. Hender; D. McCune; G. Rewoldt; S.E. Sharapov

    2001-01-01

    The transport, flow shear, and linear growth rates of microturbulence are studied for a Joint European Torus (JET) plasma with high central q in which an internal transport barrier (ITB) forms and grows to a large radius. The linear microturbulence growth rates of the fastest growing (most unstable) toroidal modes with high toroidal mode number are calculated using the GS2 and FULL gyrokinetic codes. These linear growth rates, gamma (subscript lin) are large, but the flow-shearing rates, gamma (subscript ExB) (dominated by the toroidal rotation contribution) are also comparably large when and where the ITB exists

  10. Kolmogorov flow in two dimensional strongly coupled dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Akanksha; Ganesh, R., E-mail: ganesh@ipr.res.in; Joy, Ashwin [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 382 428 (India)

    2014-07-15

    Undriven, incompressible Kolmogorov flow in two dimensional doubly periodic strongly coupled dusty plasma is modelled using generalised hydrodynamics, both in linear and nonlinear regime. A complete stability diagram is obtained for low Reynolds numbers R and for a range of viscoelastic relaxation time τ{sub m} [0 < τ{sub m} < 10]. For the system size considered, using a linear stability analysis, similar to Navier Stokes fluid (τ{sub m} = 0), it is found that for Reynolds number beyond a critical R, say R{sub c}, the Kolmogorov flow becomes unstable. Importantly, it is found that R{sub c} is strongly reduced for increasing values of τ{sub m}. A critical τ{sub m}{sup c} is found above which Kolmogorov flow is unconditionally unstable and becomes independent of Reynolds number. For R < R{sub c}, the neutral stability regime found in Navier Stokes fluid (τ{sub m} = 0) is now found to be a damped regime in viscoelastic fluids, thus changing the fundamental nature of transition of Kolmogorov flow as function of Reynolds number R. A new parallelized nonlinear pseudo spectral code has been developed and is benchmarked against eigen values for Kolmogorov flow obtained from linear analysis. Nonlinear states obtained from the pseudo spectral code exhibit cyclicity and pattern formation in vorticity and viscoelastic oscillations in energy.

  11. Equilibrium measurements on the REPUTE-1 RFP plasma

    International Nuclear Information System (INIS)

    Ji, H.; Toyama, H.; Shinohara, S.; Fujisawa, A.; Yamagishi, K.; Shimazu, Y.; Ejiri, A.; Shimoji, K.; Miyamoto, K.

    1989-01-01

    Global plasma equilibrium measurements by external magnetic probes are widely introduced on the toroidal plasmas, i.e. tokamaks or RFPs, because of their simplicity and convenience. The measurement principle is based on Shafranov's toroidal equilibrium theory, which gives simple relations between the global equilibrium quantity and the external fields. These relations are valid in the either case of existence or absence of ideal shell just out the plasma column, however, not valid in the case of the thin (or resistive) shell, whose skin time τ s has the same order of the current rise time τ r . A method introduced by Swain et al. is effective in this case, in which the plasma current I p is replaced by 6 filament currents. However, by this method it is dificult to include the effect of iron core and computation requires a lot (beyond 14) of the measurement of the fields or flux loop. In this paper we introduce a simple method which is based on fitting measured fields to the vacuum approximate solution of Grad-Shafranov equation. The computation requires only a few measurements (≥6) of the fields. REPUTE-1 device is characterized by a thin shell of 5 mm thickness whose skin time τ s for the penetration of the vertical field is 1 ms compared with τ r of 0.5 ms. The optimum discharges whose duration τ d are about 3 times of τ s have been obtained. In spite of various efforts including vertical-ohmic coils series connection experiments, toroidal ripple reduction experiments and port bypass plate installation experiments, until now τ d is still limited by 3.2 ms. We should think that the equilibrium of plasma is lost due to an unfavorable vertical field. In this paper we present the measurements of the time evolution of the plasma position from the flat-top phase to the termination phase, at that time the plasma begins to lose its equilibrium. The liner has a major radius R L of 82 cm and a minor radius a L of 22 cm. (author) 6 refs., 4 figs

  12. Plasma-enhanced mixing and flameholding in supersonic flow.

    Science.gov (United States)

    Firsov, Alexander; Savelkin, Konstantin V; Yarantsev, Dmitry A; Leonov, Sergey B

    2015-08-13

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure P(st)=160-250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W(pl)=3-24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air-fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  13. Temperature measurements in thermonuclear plasmas

    International Nuclear Information System (INIS)

    Breton, D.

    1958-01-01

    The temperatures needed to produce thermonuclear reactions are of the order of several million degrees Kelvin. Devising methods for measuring such temperatures has been the subject of research in many countries. In order to present the problem clearly and to demonstrate its importance, the author reviews the various conditions which must be fulfilled in order that reactions may be qualified as thermonuclear. The relationship between the temperature and the cross-section of the reactions is studied, and it is shown that the notion of temperature in the plasmas is complex, which leads to a consideration of the temperature of the ions and that of the electrons. None of the methods for the temperature measurements is completely satisfactory because of the hypotheses which must be made, and which are seldom fulfilled during high-intensity discharges in the plasmas. In practice it is necessary to use several methods simultaneously. (author) [fr

  14. Correlation measurements for fusion plasma diagnostics

    International Nuclear Information System (INIS)

    Pazsit, I.

    1995-01-01

    A list of a few methods for plasma diagnostics via fluctuations (noise) analysis of random (both temporally and spatially) system parameters is reviewed. Analogy is drawn with certain noise analysis methods, used in the diagnostics of fission reactors. These methods have been applied also to fusion measurements to some extent. However, the treatment of fusion plasma fluctuations is dominated by an approach that allows for temporal randomness, but assumes periodicity in space. This approach suits well a large class of phenomena such as magnetic fluctuations (MHD effects), but is much less suited to treat localised effects such as turbulence and density fluctuations. This paper discusses the potentials of the former approach, i.e. ordinary noise analysis methods of non-periodic variables in fusion plasma diagnostics. A new recommendation is to use the crossed beam correlation analysis of soft X-ray signals for determining the local short-range correlations in the plasma and to perform a systematic exploration of the plasma spatial correlation structure with that and other methods. 16 refs, 7 figs

  15. Quantitative tomographic measurements of opaque multiphase flows

    Energy Technology Data Exchange (ETDEWEB)

    GEORGE,DARIN L.; TORCZYNSKI,JOHN R.; SHOLLENBERGER,KIM ANN; O' HERN,TIMOTHY J.; CECCIO,STEVEN L.

    2000-03-01

    An electrical-impedance tomography (EIT) system has been developed for quantitative measurements of radial phase distribution profiles in two-phase and three-phase vertical column flows. The EIT system is described along with the computer algorithm used for reconstructing phase volume fraction profiles. EIT measurements were validated by comparison with a gamma-densitometry tomography (GDT) system. The EIT system was used to accurately measure average solid volume fractions up to 0.05 in solid-liquid flows, and radial gas volume fraction profiles in gas-liquid flows with gas volume fractions up to 0.15. In both flows, average phase volume fractions and radial volume fraction profiles from GDT and EIT were in good agreement. A minor modification to the formula used to relate conductivity data to phase volume fractions was found to improve agreement between the methods. GDT and EIT were then applied together to simultaneously measure the solid, liquid, and gas radial distributions within several vertical three-phase flows. For average solid volume fractions up to 0.30, the gas distribution for each gas flow rate was approximately independent of the amount of solids in the column. Measurements made with this EIT system demonstrate that EIT may be used successfully for noninvasive, quantitative measurements of dispersed multiphase flows.

  16. Electric field measurements in moving ionization fronts during plasma breakdown

    NARCIS (Netherlands)

    Wagenaars, E.; Bowden, M.D.; Kroesen, G.M.W.

    2006-01-01

    We have performed time-resolved, direct measurements of electric field strengths in moving ionization fronts during the breakdown phase of a pulsed plasma. Plasma breakdown, or plasma ignition, is a highly transient process marking the transition from a gas to a plasma. Some aspects of plasma

  17. Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

    International Nuclear Information System (INIS)

    Jacquet, L.; Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G.

    2015-01-01

    The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and

  18. Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

    Science.gov (United States)

    Jacquet, L.; Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G.

    2015-12-01

    The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and the

  19. Measurements and non-local thermodynamic equilibrium modeling of mid-Z plasma emission

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet, L., E-mail: laurent.jacquet@cea.fr; Primout, M.; Kaiser, P.; Clouët, J. F.; Girard, F.; Villette, B.; Reverdin, C.; Oudot, G. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2015-12-15

    The x-ray yields from laser-irradiated thin foils of iron, copper, zinc, and germanium have been measured in the soft and multi-keV x-ray ranges at the OMEGA laser at the Laboratory for Laser Energetics. The incident laser power had a pre-pulse to enhance the x-ray emission of a 1 ns flat-top main pulse. The experimental results have been compared with post-shot simulations performed with the two-dimensional radiation-hydrodynamics code FCI2. A new non-local thermodynamic equilibrium model, NOO-RAD, have been incorporated into FCI2. In this approach, the plasma ionization state is in-line calculated by the atomic physics NOHEL package. In the soft x-ray bands, both simulations using RADIOM [M. Busquet, Phys. Fluids B 5, 4191 (1993)] and NOO-RAD clearly over-predict the powers and energies measured by a broad-band spectrometer. In one case (the iron foil), the discrepancy between the measured and simulated x-ray output is nevertheless significantly reduced when NOO-RAD is used in the simulations. In the multi-keV x-ray bands, the simulations display a strong sensitivity to the coupling between the electron thermal conductivity and the NLTE models, and for some particular combinations of these, provide a close match to the measured emission. The comparison between the measured and simulated H-like to He-like line-intensity ratios deduced from high-resolution spectra indicates higher experimental electron temperatures were achieved, compared to the simulated ones. Measurements of the plasma conditions have been achieved using the Thomson-scattering diagnostic. The electron temperatures are found to range from 3 to 5 keV at the end of the laser pulse and are greater than predicted by the simulations. The measured flow velocities are in reasonable agreement with the calculated ones. This last finding gives us confidence in our numerical predictions for the plasma parameters, which are over that time mainly determined by hydrodynamics, such as the mass densities and

  20. Computational modeling of plasma-flow switched foil implosions

    International Nuclear Information System (INIS)

    Lindemuth, I.R.

    1985-01-01

    A ''plasma-flow'', or ''commutator'', switch has been proposed as a means of achieving high dI/dt in a radially imploding metallic foil plasma. In this concept, an axially moving foil provides the initial coaxial gun discharge path for the prime power source and provides and ''integral'' inductive storage of magnetic energy. As the axially moving foil reaches the end of the coaxial gun, a radially imploding load foil is switched into the circuit. The authors have begun two-dimensional computer modeling of the two-foil implosion system. They use a magnetohydrodynamic (MHD) model which includes tabulated state and transport properties of the metallic foil material. Moving numerical grids are used to achieve adequate resolution of the moving foils. A variety of radiation models are used to compute the radiation generated when the imploding load foil converges on axis. These computations are attempting to examine the interaction of the switching foil with the load foil. In particular, they examine the relationship between foil placement and implosion quality

  1. Simultaneous Determination of Glomerular Filtration Rate with {sup 125}I-Iothalamate and Effective Renal Plasma Flow with {sup 131}I-Hippuran

    Energy Technology Data Exchange (ETDEWEB)

    Houwen, B.; Donker, A. J.M.; Woldring, M. G.; Beekhuis, H.; Zanten, A.K. van; Looye, A.; Hem, G.K. van der [Department Of Internal Medicine, Central Isotope Laboratory, University of Groningen, Groningen (Netherlands)

    1971-02-15

    The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in patients with normal and abnormal renal functions. {sup 125}I-iothalamate and inulin were used for the estimation of the GFR; {sup 131}I-Hippuran, p-aminohippuric acid and p-acetylaminohippuric acid were used for the ERPF determination. Procedure involved the continuous infusion of a solution containing {sup 125}I-iothalamate, {sup 131}I-Hippuran, inulin and PAH or PACAH, intravenously administered by an infusion pump. The clearances were determined in two ways: (1) By means of the standard technique, i.e. the equation, (urine concentration x urine volume)/plasma concentration: (2) By using the equation, intravenous dose per minute/plasma concentration. Comparisons between the methods are made. (author)

  2. Development of measurement method of void fraction distribution on subcooled flow boiling using neutron radiography

    International Nuclear Information System (INIS)

    Kureta, Masatoshi; Matsubayashi, Masahito; Akimoto, Hajime

    1999-03-01

    In relation to the development of a solid target of high intensity neutron source, plasma-facing components of fusion reactor and so forth, it is indispensable to estimate the void fraction for high-heat-load subcooled flow boiling of water. Since the existing prediction method of void fraction is based on the database for tubes, it is necessary to investigate extendibility of the existing prediction method to narrow-gap rectangular channels that is used in the high-heat-load devices. However, measurement method of void fraction in the narrow-gap rectangular channel has not been established yet because of the difficulty of measurement. The objectives of this investigation are development of a new system for bubble visualization and void fraction measurement on subcooled flow boiling in narrow-gap rectangular channels using the neutron radiography, and establishment of void fraction database by using this measurement system. This report describes the void fraction measurement method by the neutron radiography technique, and summarizes the measured void fraction data in one-side heated narrow-gap rectangular channels at subcooled boiling condition. (author)

  3. An electrode polarization impedance based flow sensor for low water flow measurement

    International Nuclear Information System (INIS)

    Yan, Tinghu; Sabic, Darko

    2013-01-01

    This note describes an electrode polarization impedance based flow sensor for low water flow measurement. It consists of two pairs of stainless steel electrodes set apart and inserted into a non-conductive flow tube with each pair of electrodes placed diametrically at the opposite sides. The flow sensor is modeled as a typical four-electrode system of which two electrodes are current-carrying and the other two serve as output pick ups. The polarization impedances of the two current carrying electrodes are affected by water flows resulting in changes of differential potential between the two pick-up electrodes which are separated by the same fluid. The interrogation of the two excitation electrodes with dc biased ac signals offers significantly higher sensor sensitivities to flow. The prototype flow sensor constructed for a 20 mm diameter pipeline was able to measure water flow rate as low as tested at 1.06 l h −1 and remained sensitive at a flow rate of 25.18 l h −1 when it was driven with a sinusoidal voltage at 1000 Hz with a peak ac amplitude of 2 V and a dc offset of +8 V. The nonlinear characteristics of the sensor response indicate that the sensor is more sensitive at low flows and will not be able to measure at very high flows. Additional experiments are needed to evaluate the influences of impurities, chemical species, ions constituents, conductivity and temperature over a practical range of residential water conditions, the effects of fluctuating ground signals, measurement uncertainty, power consumption, compensation of effects and practical operations. The flow sensor (principle) presented may be used as (in) a secondary sensor in combination with an existing electronic water meter to extend the low end of measurement range in residential water metering. (technical design note)

  4. Topological structures of vortex flow on a flying wing aircraft, controlled by a nanosecond pulse discharge plasma actuator

    Science.gov (United States)

    Du, Hai; Shi, Zhiwei; Cheng, Keming; Wei, Dechen; Li, Zheng; Zhou, Danjie; He, Haibo; Yao, Junkai; He, Chengjun

    2016-06-01

    Vortex control is a thriving research area, particularly in relation to flying wing or delta wing aircraft. This paper presents the topological structures of vortex flow on a flying wing aircraft controlled by a nanosecond plasma dielectric barrier discharge actuator. Experiments, including oil flow visualization and two-dimensional particle image velocimetry (PIV), were conducted in a wind tunnel with a Reynolds number of 0.5 × 106. Both oil and PIV results show that the vortex can be controlled. Oil topological structures on the aircraft surface coincide with spatial PIV flow structures. Both indicate vortex convergence and enhancement when the plasma discharge is switched on, leading to a reduced region of separated flow.

  5. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.

    Science.gov (United States)

    Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A

    2015-08-13

    The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  6. Interferometer for electron density measurement in exploding wire plasma

    International Nuclear Information System (INIS)

    Batra, Jigyasa; Jaiswar, Ashutosh; Kaushik, T.C.

    2016-12-01

    Mach-Zehnder Interferometer (MZI) has been developed for measuring electron density profile in pulsed plasmas. MZI is to be used for characterizing exploding wire plasmas for correlating electron density dynamics with x-rays emission. Experiments have been carried out for probing electron density in pulsed plasmas produced in our laboratory like in spark gap and exploding wire plasmas. These are microsecond phenomenon. Changes in electron density have been registered in interferograms with the help of a streak camera for specific time window. Temporal electron density profiles have been calculated by analyzing temporal fringe shifts in interferograms. This report deals with details of MZI developed in our laboratory along with its theory. Basic introductory details have also been provided for exploding wire plasmas to be probed. Some demonstrative results of electron density measurements in pulsed plasmas of spark gap and single exploding wires have been described. (author)

  7. MHD equilibrium of toroidal fusion plasma with stationary flows; Rownowaga MHD toroidalnej plazmy termojadrowej z przeplywami

    Energy Technology Data Exchange (ETDEWEB)

    Galkowski, A. [Institute of Atomic Energy, Otwock-Swierk (Poland)

    1994-12-31

    Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad`s ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs.

  8. Potential flow model for the hydromagnetic Rayleigh--Taylor instability in cylindrical plasmas

    International Nuclear Information System (INIS)

    Hwang, C.S.; Roderick, N.F.

    1987-01-01

    A potential flow model has been developed to study the linear behavior of the hydromagnetic equivalent of the Rayleigh--Taylor instability in imploding cylindrical plasmas. Ordinary differential equations are obtained for both (r,z) and (r,θ) disturbances. The model allows the study of the dynamic effects of the moving plasma on the development of the instability. The perturbation equations separate into a geometric part associated with the motion of the interface and a nongeometric part associated with the stability of the interface. In both planes the geometric part shows growth of perturbations for imploding plasmas. The surface is also unstable in both planes for plasmas being imploded by magnetic fields. Analytic solutions are obtained for constant acceleration. These show that the short wavelength perturbations that are most damaging in the (r,z) plane are not affected by the motion of the interface. In the (r,θ) plane the growth of longer wavelength disturbances is affected by the interface motion

  9. Evidence of flow stabilization in the ZaP Z pinch experiment

    International Nuclear Information System (INIS)

    Shumlak, U.; Crawford, E.; Golingo, R.P.; Nelson, B.A.; Zyrmpas, A.; Den Hartog, D.J.; Holly, D.J.

    2001-01-01

    The stabilizing effect of an axial flow on the m = 1 kink instability in Z pinches has been studied numerically with a linearized ideal MHD model to reveal that a sheared axial flow stabilizes the kink mode when the shear exceeds a threshold. The sheared flow stabilizing effect is investigated with the flow-through Z pinch experiment, ZaP. An azimuthal array of surface mounted magnetic probes located at the midplane of the 50 cm long pinch plasma measures the fluctuation levels of the azimuthal modes m=1, 2, and 3. After pinch formation a quiescent period is found where the mode activity is reduced to a few percent of the average field. Optical images from a fast framing camera and a HeNe interferometer also indicate a stable pinch plasma during this time. Doppler shift measurements of a C-III line correspond to an axial flow velocity of 9.6x10 4 m/s internal to the pinch. During the time when the axial plasma flow is high, the plasma experiences a quiescent period which lasts approximately 800 exponential growth times predicted by linear theory for a static plasma. (author)

  10. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    Science.gov (United States)

    Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

    2012-01-01

    We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

  11. Structural power flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Falter, K.J.; Keltie, R.F.

    1988-12-01

    Previous investigations of structural power flow through beam-like structures resulted in some unexplained anomalies in the calculated data. In order to develop structural power flow measurement as a viable technique for machine tool design, the causes of these anomalies needed to be found. Once found, techniques for eliminating the errors could be developed. Error sources were found in the experimental apparatus itself as well as in the instrumentation. Although flexural waves are the carriers of power in the experimental apparatus, at some frequencies longitudinal waves were excited which were picked up by the accelerometers and altered power measurements. Errors were found in the phase and gain response of the sensors and amplifiers used for measurement. A transfer function correction technique was employed to compensate for these instrumentation errors.

  12. Temperature Measurements of Dense Plasmas by Detailed Balance

    International Nuclear Information System (INIS)

    Holl, A; Redmer, R; Ropke, G; Reinholz, H; Thiele, R; Fortmann, C; Forster, E; Cao, L; Tschentscher, T; Toleikis, S; Glenzer, S H

    2006-01-01

    Plasmas at high electron densities of n e = 10 20 - 10 26 cm -3 and moderate temperatures T e = 1 - 20 eV are important for laboratory astrophysics, high energy density science and inertial confinement fusion. These plasmas are usually referred to as Warm Dense Matter (WDM) and are characterized by a coupling parameter of Λ ∼> 1 where correlations become important. The characterization of such plasmas is still a challenging task due to the lack of direct measurement techniques for temperatures and densities. They propose to measure the Thomson scattering spectrum of vacuum-UV radiation off density fluctuations in the plasma. Collective Thomson scattering provides accurate data for the electron temperature applying first principles. Further, this method takes advantage of the spectral asymmetry resulting from detailed balance and is independent of collisional effects in these dense systems

  13. Plasma generated in culture medium induces damages of HeLa cells due to flow phenomena

    Science.gov (United States)

    Sato, Yusuke; Sato, Takehiko; Yoshino, Daisuke

    2018-03-01

    Plasma in a liquid has been anticipated as an effective tool for medical applications, however, few reports have described cellular responses to plasma generated in a liquid similar to biological fluids. Herein we report the effects of plasma generated in a culture medium on HeLa cells. The plasma in the culture medium produced not only heat, shock waves, and reactive chemical species but also a jet flow with sub millimeter-sized bubbles. Cells exposed to the plasma exhibited detachment, morphological changes, and changes in the actin cytoskeletal structure. The experimental results suggest that wall shear stress over 160 Pa was generated on the surface of the cells by the plasma. It is one of the main factors that cause those cellular responses. We believe that our findings would provide valuable insight into advancements in medical applications of plasma in a liquid.

  14. Biomolecular Nano-Flow-Sensor to Measure Near-Surface Flow

    Directory of Open Access Journals (Sweden)

    Noji Hiroyuki

    2009-01-01

    Full Text Available Abstract We have proposed and experimentally demonstrated that the measurement of the near-surface flow at the interface between a liquid and solid using a 10 nm-sized biomolecular motor of F1-ATPase as a nano-flow-sensor. For this purpose, we developed a microfluidic test-bed chip to precisely control the liquid flow acting on the F1-ATPase. In order to visualize the rotation of F1-ATPase, several hundreds nanometer-sized particle was immobilized at the rotational axis of F1-ATPase to enhance the rotation to be detected by optical microscopy. The rotational motion of F1-ATPase, which was immobilized on an inner surface of the test-bed chip, was measured to obtain the correlation between the near-surface flow and the rotation speed of F1-ATPase. As a result, we obtained the relationship that the rotation speed of F1-ATPase was linearly decelerated with increasing flow velocity. The mechanism of the correlation between the rotation speed and the near-surface flow remains unclear, however the concept to use biomolecule as a nano-flow-sensor was proofed successfully. (See supplementary material 1 Electronic supplementary material The online version of this article (doi:10.1007/s11671-009-9479-3 contains supplementary material, which is available to authorized users. Click here for file

  15. Experiments and theory in non-linear thermal transport, heat flow instabilities and plasma jet formation in inertial confinement

    International Nuclear Information System (INIS)

    Haines, M.G.; Bond, D.J.; Chuaqui, H.H.

    1983-01-01

    The paper reports experimental and theoretical contributions to the understanding of non-linear heat flow and the phenomenon of jet-like filamentary structures in inertial-confinement fusion. When lateral heat flow is minimized, through applying more carefully a radially symmetric irradiation at 1.05 and 0.53 μm on a spherical target, it is found that a heat flux in excess of 10% of the free-streaming limit is consistent with simulations and experimental measurements with particle and X-ray diagnostics. A similar result has been found in a scaled experiment in a plasma of electron density 4x10 16 cm - 3 when the condition Tsub(e) approx.=Tsub(i) is satisfied. These results are in marked contrast to earlier assertions, mainly from plane-target measurements, that the flux limiter is 3%, but in agreement with theoretical calculations of steady non-linear heat flow using a discrete-ordinate method. Thus, no anomalous inhibition of heat flow is found, consistent with theoretical predictions that ion-acoustic turbulence is of no importance in dense (n>=10 21 cm - 3 , T approx.= 1 keV) plasmas. However, in the low-density scaled experiment, under conditions where Tsub(e)>>Tsub(i) is found that ion-acoustic turbulence is present, and the flux limiter is 4%. By using shadowgraphic and schlieren techniques with an optical diagnostic probe, fine-scale jet-like structures have been observed on a scale-length of approx. 10 μm on spherical targets. They occur even outside the laser-irradiated region, and are not connected with irregularities in the laser beam; they are more pronounced with higher-Z materials and with shorter-wavelength lasers, and have megagauss magnetic fields associated with them. Electromagnetic instabilities driven by heat flow are the probable cause of the jets, and of the three known modes the thermal instability, enhanced by radiation loss, agrees more closely with the experiments than the Weibel and thermomagnetic modes, since the latter only occur

  16. Radiometric methods in the measurement of particle-laden flows

    Czech Academy of Sciences Publication Activity Database

    Zych, M.; Hanus, R.; Vlasák, Pavel; Jaszczur, M.; Petryka, L.

    2017-01-01

    Roč. 318, August (2017), s. 491-500 ISSN 0032-5910 Institutional support: RVO:67985874 Keywords : particle-laden flow * radiotracer * gamma absorption * cross-correlation * polymetallic nodules Subject RIV: BK - Fluid Dynamics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.942, year: 2016

  17. The influence of plasma flows bringing the magnetotail back to a more symmetric configuration

    Science.gov (United States)

    Reistad, J. P.; Østgaard, N.; Laundal, K.; Tenfjord, P.; Snekvik, K.; Haaland, S.; Milan, S. E.; Ohma, A.; Grocott, A.; Oksavik, K.

    2017-12-01

    Research from the past decades, most importantly conjugate studies, have shown extensive evidence of the Earth's closed magnetotail being highly displaced from the quiet-day configuration in response to the IMF interacting with the magnetosphere. By displaced we here refer to the mapping of magnetic field-lines from one hemisphere to the other. The large-scale ionospheric convection related to such displaced closed field-lines has also been studied, showing that the footprint in one hemisphere tend to move faster to reduce the displacement, a process we refer to as the restoring of symmetry. Although the appearance and occurrence of the plasma flows related to the restoring of symmetry has been shown to have a strong Interplanetary Magnetic Field (IMF) control, its dynamics and relation to internal magnetospheric processes are unknown. Using multiple years of line-of-sight measurements of the ionospheric plasma convection from the Super Dual Auroral Radar Network binned by IMF, season, and SML index, we have found that the restoring symmetry flows dominate the average convection pattern in the nightside ionosphere during low levels of magnetotail activity, quantified by the SML index. For increasing magnetotail activity, signatures of the restoring symmetry process become less and less pronounced in the global average convection maps. This effect is seen for all clock angles away from IMF By = 0. These results are relevant in order to better understand the dynamic evolution of flux-tubes in the asymmetric magnetosphere.

  18. Quantifying measurement uncertainties in ADCP measurements in non-steady, inhomogeneous flow

    Science.gov (United States)

    Schäfer, Stefan

    2017-04-01

    The author presents a laboratory study of fixed-platform four-beam ADCP and three-beam ADV measurements in the tailrace of a micro hydro power setup with a 35kW Kaplan-turbine and 2.5m head. The datasets discussed quantify measurement uncertainties of the ADCP measurement technique coming from non-steady, inhomogeneous flow. For constant discharge of 1.5m3/s, two different flow scenarios were investigated: one being the regular tailrace flow downstream the draft tube and the second being a straightened, less inhomogeneous flow, which was generated by the use of a flow straightening device: A rack of diameter 40mm pipe sections was mounted right behind the draft tube. ADCP measurements (sampling rate 1.35Hz) were conducted in three distances behind the draft tube and compared bin-wise to measurements of three simultaneously measuring ADV probes (sampling rate 64Hz). The ADV probes were aligned horizontally and the ADV bins were placed in the centers of two facing ADCP bins and in the vertical under the ADCP probe of the corresponding depth. Rotating the ADV probes by 90° allowed for measurements of the other two facing ADCP bins. For reasons of mutual probe interaction, ADCP and ADV measurements were not conducted at the same time. The datasets were evaluated by using mean and fluctuation velocities. Turbulence parameters were calculated and compared as far as applicable. Uncertainties coming from non-steady flow were estimated with the normalized mean square error und evaluated by comparing long-term measurements of 60 minutes to shorter measurement intervals. Uncertainties coming from inhomogeneous flow were evaluated by comparison of ADCP with ADV data along the ADCP beams where ADCP data were effectively measured and in the vertical under the ADCP probe where velocities of the ADCP measurements were displayed. Errors coming from non-steady flow could be compensated through sufficiently long measurement intervals with high enough sampling rates depending on the

  19. Electrical Characteristics of Carbon Nanotubes by Plasma and Microwave Surface Treatments

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sangjin; Lee, Soonbo; Boo, Jinhyo [Sungkyunkwan Univ., Suwon (Korea, Republic of); Shrestha, Shankar Prasad [Tribhuvan Univ., Kathmandu (Nepal)

    2014-03-15

    The plasma and microwave surface treatments of carbon nanotubes that loaded on plastic substrates were carried out with expecting a change of carbon nanotube dispersion by increasing treatment time. The microwave treatment process was undergone by commercial microwave oven (800 W). The electrical property was measured by hall measurement and resistance was increased by increasing O{sub 2} flow rate of plasma, suggesting an improvement of carbon nanotube dispersion and a possibility of controlling the resistances of carbon nanotubes by plasma surface treatment. The resistance was increased in both polyethylene terephthalate and polyimide substrates by increasing O{sub 2} flow rate. Resistance changes only slightly with different O{sub 2} flow treatment in measure rho for all polyimide samples. Sheet resistance is lowest in polyimide substrate not due to high carbon nanotube loading but due to tendency to remain in elongated structure. O{sub 2} or N{sub 2} plasma treatments on both polyethylene terephthalate and polyimide substrates lead to increase in sheet resistance.

  20. Electrical Characteristics of Carbon Nanotubes by Plasma and Microwave Surface Treatments

    International Nuclear Information System (INIS)

    Cho, Sangjin; Lee, Soonbo; Boo, Jinhyo; Shrestha, Shankar Prasad

    2014-01-01

    The plasma and microwave surface treatments of carbon nanotubes that loaded on plastic substrates were carried out with expecting a change of carbon nanotube dispersion by increasing treatment time. The microwave treatment process was undergone by commercial microwave oven (800 W). The electrical property was measured by hall measurement and resistance was increased by increasing O 2 flow rate of plasma, suggesting an improvement of carbon nanotube dispersion and a possibility of controlling the resistances of carbon nanotubes by plasma surface treatment. The resistance was increased in both polyethylene terephthalate and polyimide substrates by increasing O 2 flow rate. Resistance changes only slightly with different O 2 flow treatment in measure rho for all polyimide samples. Sheet resistance is lowest in polyimide substrate not due to high carbon nanotube loading but due to tendency to remain in elongated structure. O 2 or N 2 plasma treatments on both polyethylene terephthalate and polyimide substrates lead to increase in sheet resistance

  1. Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

    NARCIS (Netherlands)

    Helsper, J.P.F.G.; Peters, R.J.B.; Bemmel, M.E.M. van; Rivera, Z.E.H.; Wagner, S.; Kammer, F. von der; Tromp, P.C.; Hofmann, T.; Weigel, S.

    2016-01-01

    Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass spectrometry

  2. Enhanced confinement with plasma biasing in the MST reversed field pinch

    International Nuclear Information System (INIS)

    Craig, D.; Almagri, A.F.; Anderson, J.K.

    1997-06-01

    We report an increase in particle confinement with plasma biasing in a reversed field pinch. Miniature plasma sources are used as electrodes to negatively bias the plasma at the edge (r/a ∼ 0.9). Particle content increases and H α radiation decreases upon application of bias and global particle confinement roughly doubles as a result. Measurements of plasma potential, impurity flow, and floating potential fluctuations indicate that strong flows are produced and that electrostatic fluctuations are reduced

  3. Zonal flows and turbulence in fluids and plasmas

    Science.gov (United States)

    Parker, Jeffrey Bok-Cheung

    In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking 'zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetric coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flows constitute pattern formation amid a turbulent bath. Zonostrophic instability is an example of a Type I s instability of pattern-forming systems. The broken symmetry is statistical homogeneity. Near the bifurcation point, the slow dynamics of CE2 are governed by a well-known amplitude equation, the real Ginzburg-Landau equation. The important features of this amplitude equation, and therefore of the CE2 system, are multiple. First, the zonal flow wavelength is not unique. In an idealized, infinite system, there is a continuous band of zonal flow wavelengths that allow a nonlinear equilibrium. Second, of these wavelengths, only those within a smaller subband are stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets. These behaviors are shown numerically to hold in the CE2 system, and we calculate a stability diagram. The stability diagram is in agreement with direct numerical simulations of the quasilinear

  4. The measurement of low air flow velocities

    NARCIS (Netherlands)

    Aghaei, A.; Mao, X.G.; Zanden, van der A.J.J.; Schaik, W.H.J.; Hendriks, N.A.

    2005-01-01

    Air flow velocity is measured with an acoustic sensor, which can be used especially for measuring low air flow velocities as well as the temperature of the air simultaneously. Two opposite transducers send a sound pulse towards each other. From the difference of the transit times, the air flow

  5. Optimization of laser-induced breakdown spectroscopy for coal powder analysis with different particle flow diameters

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Shunchun, E-mail: epscyao@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); State Key Laboratory of Pulsed Power Laser Technology, Electronic Engineering Institute, Hefei 230037 (China); Xu, Jialong; Dong, Xuan; Zhang, Bo; Zheng, Jianping [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Lu, Jidong, E-mail: jdlu@scut.edu.cn [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China)

    2015-08-01

    The on-line measurement of coal is extremely useful for emission control and combustion process optimization in coal-fired plant. Laser-induced breakdown spectroscopy was employed to directly analyze coal particle flow. A set of tapered tubes were proposed for beam-focusing the coal particle flow to different diameters. For optimizing the measurement of coal particle flow, the characteristics of laser-induced plasma, including optical breakdown, the relative standard deviation of repeated measurement, partial breakdown spectra ratio and line intensity, were carefully analyzed. The comparison of the plasma characteristics among coal particle flow with different diameters showed that air breakdown and the random change in plasma position relative to the collection optics could significantly influence on the line intensity and the reproducibility of measurement. It is demonstrated that the tapered tube with a diameter of 5.5 mm was particularly useful to enrich the coal particles in laser focus spot as well as to reduce the influence of air breakdown and random changes of plasma in the experiment. - Highlights: • Tapered tube was designed for beam-focusing the coal particle flow as well as enriching the particles in laser focus spot. • The characteristics of laser-induced plasma of coal particle flow were investigated carefully. • An appropriate diameter of coal particle flow was proven to benefit for improving the performance of LIBS measurement.

  6. Our experience of blood flow measurements using radioactive tracers

    International Nuclear Information System (INIS)

    Danet, Bernard.

    1974-01-01

    A critical study of blood flow measuring methods is proposed. After a review of the various diffusible and non-diffusible radioactive tracers and the corresponding detector systems, the principles which allow to measure blood flow from the data so obtained, are studied. There is a different principle of flow measurement for each type of tracer. The theory of flow measurement using non-diffusible tracers (human serum albumin labelled with 131 I or sup(99m)Tc, 113 In-labelled siderophiline) and its application to cardiac flow measurement are described first. Then the theory of flow measurement using diffusible tracers ( 133 Xe, 85 Kr) and its application to measurement of blood flow through tissues (muscles and kidney particularly) are described. A personal experience of this various flow measurements is reported. The results obtained, the difficulties encountered and the improvments proposed are developed [fr

  7. Power Transfer to plasma Coxial accelerator

    International Nuclear Information System (INIS)

    El-Aragi, G.M.; Soliman, H.M.; Masoud, M.M.

    2000-01-01

    The total power transfer from the condenser bank, to plasma coaxial accelerator device is theoretically studied by using the voltage equation of the entire circuit and applying impulse - linear momentum theorem. This total power represents a combination of (a) the power flowing to the external inductance, (b) the power flowing to the inductance of that part of electrode system between the breech and the momentary position of the plasma current sheath, (c) the power flowing in the annular space between the two coaxial electrodes, to form the magnetic field induction, (d) the power flowing to accelerate the initial mass, (e) the power flowing to accelerate the mass, which has been swept up into the plasma current sheath, (f) the power, which produces directed kinetic energy for the plasma current sheath, (g) the power, which produces internal energy in the plasma sheath, (h) the joule heating. The peak value of the total power = 6x10 8 watt at t=4 MUs, for maximum calculated discharge current = 110KA with a with a period of 34 us. Experimentally its equal to 3.5x10 8 watt at 7MUs and I 0 = 85KA. The energy flow to the coaxial discharge system has been evaluated theoretically and experimentally, E-MAX (CALCULATED)=5.92X10 2 J AT T = 5.5 MUs and E m ax (measured) = 3.54x10 2 joule at 7.5 MUs

  8. Flowing afterglow: construction of an apparatus, measurement of rate constants, and consideration of the diffusive behavior of charges

    International Nuclear Information System (INIS)

    Matsuoka, Shingo; Nakamura, Hirone; Tamura, Takaaki; Fujii, Toshihiro.

    1984-01-01

    A flowing afterglow apparatus was constructed and the operation of the afterglow system including data analysis was tested by measuring the rate constants for the reactions N + + NO, N 2 + + NO, He + + N 2 , and SF 6 + e; the results were 5.8 x 10 -10 , 3.9 x 10 -10 , 1.20 x 10 -9 , and 2.1 x 10 -7 cm 3 s -1 respectively. In the measurements an extraction voltage for ion sampling was not applied to the nose cone in order not to introduce an electric field into the reaction region. A ''non-ambipolar'' model developed by us was used for the data analysis of the ion/molecule reactions. For the data analysis of the electron attachment, a typical curve fit mehtod to the product ion signal was used. However, no theoretical curves fit the experimental points. This disagreement is attributed to a change of the ion-sampling efficiency through the nose-cone aperture arising from a change of the electron-dominated plasma to a negative-ion-dominated plasma with an increasing flow rate of SF 6 . Nevertheless, the attachment rate could be determined by fitting the theoretical and experimantal curves in the limited region of the SF 6 flow rate where the negative-ion-dominated plasma is established at the sampling aperture. All the rate constants obtained here agree reasonably well with literature values. Next, errors in the positive ion/molecule reaction rate constants, which would occur if the diffusion coefficients of the ions and neutrals each have a + 10 % error were calculated for the flow model to be -0.4 and +1.2 % respectively, demonstrating that these parameters are not important in the analysis of data. This insensitivity explains why the nose-cone voltage applied in a typical flowing afterglow operation has not caused a significant error in the published rate constants although it disturbs the ion diffusive behavior. (author)

  9. Temperature measurement in the flowing medium

    Directory of Open Access Journals (Sweden)

    Sedlák Kamil

    2018-01-01

    Full Text Available The article deals with a brief description of methods of temperature measurements in a flowing water steam. Attention is paid to the measurement of pseudo static temperature by a single sealed thermocouple entering the flowing liquid through the flown-by wall. Then three types of probes for stagnation temperature measurement are shown, whose properties were tested using CFD calculations. The aim was to design a probe of stagnation parameters of described properties which can be used for measuring flow parameters in a real steam turbine. An important factor influencing the construction is not only the safe manipulation of the probe when inserting and removing it from the machine in operation, but also the possibility to traverse the probe along the blade length.

  10. Measurement of performance parameters of plasma source for plasma opening switch on Qiangguang-Ⅰ generator

    International Nuclear Information System (INIS)

    Luo Weixi; Zeng Zhengzhong; Lei Tianshi; Wang Liangping; Hu Yixiang; Sun Tieping; Huang Tao

    2012-01-01

    The plasma source (cable guns) of the plasma opening switch (POS) on Qiangguang Ⅰ generator was chosen as the study object. The plasma source performance was investigated by using charge collectors. Experimental results show that the plasma ejection density is positively correlated with the structural parameter, the distance between gun core tip and muzzle plane, and the plasma ejection velocity is negatively correlated with the parameter. The increasing rate of plasma ejection density is less than that of drive current. As far as a plasma source with tens of cable plasma guns is concerned, the influence of single cable gun's discharge dispersancy on plasma uniformity is little. Analysis of uncertainty shows that the uncertainty of measurement can be reduced by increasing the number of experiments and averaging the results. The combined standard uncertainty of plasma ejection density is less than 10%. (authors)

  11. Locked magnetic island chains in toroidally flow damped tokamak plasmas

    International Nuclear Information System (INIS)

    Fitzpatrick, R; Waelbroeck, F L

    2010-01-01

    The physics of a locked magnetic island chain maintained in the pedestal of an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow damping. Furthermore, the flow damping is assumed to be sufficiently strong to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the vicinity of the island chain which either increases or decreases the chain's radial width, depending on the direction of the flow. If the polarization effect is stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal and toroidal flow damping rates.

  12. Instabilities and vortex dynamics in shear flow of magnetized plasmas

    International Nuclear Information System (INIS)

    Tajima, T.; Horton, W.; Morrison, P.J.; Schutkeker, J.; Kamimura, T.; Mima, K.; Abe, Y.

    1990-03-01

    Gradient-driven instabilities and the subsequent nonlinear evolution of generated vortices in sheared E x B flows are investigated for magnetized plasmas with and without gravity (magnetic curvature) and magnetic shear by using theory and implicit particle simulations. In the linear eigenmode analysis, the instabilities considered are the Kelvin-Helmholtz (K-H) instability and the resistive interchange instability. The presence of the shear flow can stabilize these instabilities. The dynamics of the K-H instability and the vortex dynamics can be uniformly described by the initial flow pattern with a vorticity localization parameter ε. The observed growth of the K-H modes is exponential in time for linearly unstable modes, secular for marginal mode, and absent until driven nonlinearly for linearly stable modes. The distance between two vortex centers experiences rapid merging while the angle θ between the axis of vortices and the external shear flow increases. These vortices proceed toward their overall coalescence, while shedding small-scale vortices and waves. The main features of vortex dynamics of the nonlinear coalescence and the tilt or the rotational instabilities of vortices are shown to be given by using a low dimension Hamiltonian representation for interacting vortex cores in the shear flow. 24 refs., 19 figs., 1 tab

  13. INTERACTIONS OF FLOWING PLASMA WITH COLLECTING SPHERE/OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    HUTCHINSON, IAN H.

    2013-10-31

    The proposer’s computational flowing plasma group, supported in part by NSF/DOE since 2006, has been enormously productive. It has published 22 journal articles, of which 3 are in Physical Review Letters; received a total of 330 citations, and made 5 invited and numerous contributed presentations at international conferences. In addition, other groups have published at least 3 papers [20-22] based upon results they have obtained from the SCEPTIC code, developed by the proposer. The codes developed for this subject are Particle In Cell (PIC) codes, representing the entire ion distribution function and its variation in space in the vicinity of an absorbing object.

  14. Hydroelectric plant turbine, stream and spillway flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lampa, J.; Lemon, D.; Buermans, J. [ASL AQ Flow Inc., Sidney, BC (Canada)

    2004-07-01

    This presentation provided schematics of the turbine flow measurements and typical bulb installations at the Kootenay Canal and Wells hydroelectric power facilities in British Columbia. A typical arrangement for measuring stream flow using acoustic scintillation was also illustrated. Acoustic scintillation is portable, non-intrusive, suitable for short intakes, requires minimal maintenance and is cost effective and accurate. A comparison between current meters and acoustic scintillation was also presented. Stream flow measurement is valuable in evaluating downstream areas that are environmentally important for fish habitat. Stream flow measurement makes it possible to define circulation. The effects of any changes can be assessed by combining field measurements and numerical modelling. The presentation also demonstrated that computational fluid dynamics modelling appears promising in determining stream flow and turbulent flow at spillways. tabs., figs.

  15. Global characteristics of zonal flows generated by ion temperature gradient driven turbulence in tokamak plasmas

    International Nuclear Information System (INIS)

    Miyato, Naoaki; Kishimoto, Yasuaki; Li, Jiquan

    2004-08-01

    Global structure of zonal flows driven by ion temperature gradient driven turbulence in tokamak plasmas is investigated using a global electromagnetic Landau fluid code. Characteristics of the coupled system of the zonal flows and the turbulence change with the safety factor q. In a low q region stationary zonal flows are excited and suppress the turbulence effectively. Coupling between zonal flows and poloidally asymmetric pressure perturbations via a geodesic curvature makes the zonal flows oscillatory in a high q region. Also we identify energy transfer from the zonal flows to the turbulence via the poloidally asymmetric pressure perturbations in the high q region. Therefore in the high q region the zonal flows cannot quench the turbulent transport completely. (author)

  16. Measurement of tritium with plastic scintillator surface improvement with plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yoshihara, Y.; Furuta, E. [Ochanomizu University, Bunkyo-ku, Tokyo (Japan); Ohyama, R.I.; Yokota, S. [Tokai University, Hiratsuka-shi, Kanagawa (Japan); Kato, Y.; Yoshimura, T.; Ogiwara, K. [Hitachi Aloka Medical, Mure, Mitaka-shi, Tokyo (Japan)

    2015-03-15

    Tritium is usually measured by using a liquid scintillation counter. However, liquid scintillator used for measurement will become radioactive waste fluid. To solve this issue, we have developed a method of measuring tritium samples with plasma-treated plastic scintillator (PS)sheets (Plasma method). The radioactive sample is held between 2 PS sheets and the whole is enclosed in a a low-potassium glass vial. With the Plasma method of 2-min plasma treatment, we have obtained measurement efficiency of 48 ± 2 % for 2 min measurement of tritium except for tritiated water. The plasma treatment makes the PS surface rough and hydrophilic which contributes to improve the contact between tritium and PS. On the other hand, it needed almost 6 hours to obtain constant measurement efficiency. The reason was that the dry-up handling in the vial needed longer time to vaporize H{sub 2}O molecules than in the air. We tried putting silica gel beads into vials to remove H{sub 2}O molecules from PS sheet surface quickly. The silica gel beads worked well and we got constant measurement efficiency within 1-3 hours. Also, we tried using other kinds of PS treated with plasma to obtain higher measurement efficiencies of tritium samples.

  17. Physicochemical characterization of titanium dioxide pigments using various techniques for size determination and asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry

    NARCIS (Netherlands)

    Helsper, Hans; Peters, Ruud J.B.; Bemmel, van Greet; Herrera Rivera, Zahira; Wagner, Stephan; Kammer, von der Frank; Tromp, Peter C.; Hofmann, Thilo; Weigel, Stefan

    2016-01-01

    Seven commercial titanium dioxide pigments and two other well-defined TiO2 materials (TiMs) were physicochemically characterised using asymmetric flow field flow fractionation (aF4) for separation, various techniques to determine size distribution and inductively coupled plasma mass

  18. Instrument for measuring flow velocities

    International Nuclear Information System (INIS)

    Griffo, J.

    1977-01-01

    The design described here means to produce a 'more satisfying instrument with less cost' than comparable instruments known up to now. Instead of one single turbine rotor, two similar ones but with opposite blade inclination and sense of rotation are to be used. A cylindrical measuring body is carrying in its axis two bearing blocks whose shape is offering little flow resistance. On the shaft, supported by them, the two rotors run in opposite direction a relatively small axial distance apart. The speed of each rotor is picked up as pulse recurrence frequency by a transmitter and fed to an electronic measuring unit. Measuring errors as they are caused for single rotors by turbulent flow, profile distortion of the velocity, or viscous flow are to be eliminated by means of the contrarotating turbines and the subsequently added electronic unit, because in these cases the adulterating increase of the angular velocity of one rotor is compensated by a corresponding deceleration of the other rotor. The mean value then indicated by the electronic unit has high accurancy of measurement. (RW) [de

  19. A flow meter for ultrasonically measuring the flow velocity of fluids

    DEFF Research Database (Denmark)

    2015-01-01

    The invention regards a flow meter for ultrasonically measuring the flow velocity of fluids comprising a duct having a flow channel with an internal cross section comprising variation configured to generate at least one acoustic resonance within the flow channel for a specific ultrasonic frequency......, and at least two transducers for generating and sensing ultrasonic pulses, configured to transmit ultrasonic pulses at least at said specific ultrasonic frequency into the flow channel such that the ultrasonic pulses propagate through a fluid flowing in the flow channel, wherein the flow meter is configured...

  20. Plasma edge physics in an actively cooled tokamak

    International Nuclear Information System (INIS)

    Gunn, J.P.; Adamek, A.; Boucher, C.

    2005-01-01

    Tore Supra is a large tokamak with a plasma of circular cross section (major radius 2.4 m and minor radius 0.72 m) lying on a toroidal limiter. Tore Supra's main mission is the development of technology to inject up to 25 MW of microwave heating power and extract it continuously for up to 1000 s in steady state without uncontrolled overheating of, or outgassing from, plasma-facing components. The entire first wall of the tokamak is actively cooled by a high pressure water loop and special carbon fiber composite materials have been designed to handle power fluxes up to 10 MW/m 2 . The edge plasma on open magnetic flux surfaces that intersect solid objects plays an important role in the overall behaviour of the plasma. The transport of sputtered impurity ions and the fueling of the core plasma are largely governed by edge plasma density, temperature, and flow profiles. Measurements of these quantities are becoming more reliable and frequent in many tokamaks, and it has become clear that we do not understand them very well. Classical two-dimensional fluid modelling fails to reproduce many aspects of the experimental observations such as the significant thickness of the edge plasma, and the near-sonic flows that occur where none should be expected. It is suspected that plasma turbulence is responsible for these anomalies. In the Tore Supra tokamak, various kinds of Langmuir probes are used to characterize the edge plasma. We will present original measurements that demonstrate the universality of many phenomena that have been observed in X-point divertor tokamaks, especially concerning the ion flows. As in the JET tokamak, surprisingly large values of parallel Mach number are measured midway between the two strike zones, where one would expect to find nearly stagnant plasma if the particle source were poloidally uniform. We will present results of a novel experiment that provides evidence for a poloidally localized particle and energy source on the outboard midplane of

  1. Blob/hole formation and zonal-flow generation in the edge plasma of the JET tokamak

    DEFF Research Database (Denmark)

    Xu, G.S.; Naulin, Volker; Fundamenski, W.

    2009-01-01

    The first experimental evidence showing the connection between blob/hole formation and zonal-flow generation was obtained in the edge plasma of the JET tokamak. Holes as well as blobs are observed to be born in the edge shear layer, where zonal-flows shear off meso-scale coherent structures......, leading to disconnection of positive and negative pressure perturbations. The newly formed blobs transport azimuthal momentum up the gradient of the azimuthal flow and drive the zonal-flow shear while moving outwards. During this process energy is transferred from the meso-scale coherent structures...

  2. Plasma flow switch characterization for the Los Alamos Foil Implosion Project

    International Nuclear Information System (INIS)

    Bowers, R.L.; Brownell, J.H.; Greene, A.E.; Peterson, D.L.

    1990-01-01

    The next system design under consideration for the Los Alamos Foil Implosion Project is projected to deliver tens of mega-amperes of electrical current produced by high-explosive driven flux compression generators on a time scale of about one microsecond to a load foil. The use of such generators, with time scales of order several tenths of a millisecond, leads to considerable pulse shaping problems. Previously it was noted that a commutating switch might serve as an efficient alternative to a closing switch in transferring current from a coaxial transmission line to a cylindrically imploding load. Research at the Air Force Weapons Laboratory (AFWL) has met with considerable success in efficiently transferring currents of order 10 MA to an imploding liner using the plasma flow switch concept (PFS). Besides efficiently transferring current, the plasma flow switch protects the load region from high voltages generated by an opening switch until the current is present to provide magnetic insulation. For these reasons, a PFS is being investigated as the final pulse shaping step in the design. A series of capacitor bank experiments is also being fielded to help investigate physics issues and to benchmark the codes

  3. From stellar plasmas to laboratory plasmas: application to X and XUV opacity measurements

    International Nuclear Information System (INIS)

    Loisel, G.

    2011-01-01

    The general context of this thesis is the one of radiative properties of high energy density matter. Energy densities involved (>10 11 J/cm 3 ) implies that a large part of energy exchange goes through radiation-matter interactions. My studies deal with spectral opacity, a fundamental parameter for modelling stellar interiors and constitute a propitious observable to experimental tests of theoretical descriptions of hot and dense plasmas physics. Although the main application of my work is stellar plasmas it can be useful for plasma diagnostics in inertial confinement fusion. My work activities are centred on the experimental study of opacities of plasmas at local thermodynamic equilibrium for temperature conditions of a f