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Sample records for plasma self-generated electric

  1. Electrostatic wave heating and possible formation of self-generated high electric fields in a magnetized plasma

    Science.gov (United States)

    Mascali, D.; Celona, L.; Gammino, S.; Miracoli, R.; Castro, G.; Gambino, N.; Ciavola, G.

    2011-10-01

    A plasma reactor operates at the Laboratori Nazionali del Sud of INFN, Catania, and it has been used as a test-bench for the investigation of innovative mechanisms of plasma ignition based on electrostatic waves (ES-W), obtained via the inner plasma EM-to-ES wave conversion. Evidences of Bernstein wave (BW) generation will be shown. The Langmuir probe measurements have revealed a strong increase of the ion saturation current, where the BW are generated or absorbed, this being a signature of possible high energy ion flows. The results are interpreted through the Bernstein wave heating theory, which predicts the formation of high speed rotating layers of the plasma (a dense plasma ring is in fact observed). High intensity inner plasma self-generated electric fields (on the order of several tens of kV/cm) come out by our calculations.

  2. Electricity Self-Generation Costs for Industrial Companies in Cameroon

    Directory of Open Access Journals (Sweden)

    Diboma Benjamin Salomon

    2010-07-01

    Full Text Available Industrial production in developing countries (DC is frequently perturbed by electric energy supply difficulties. To overcome this problem, generators are used in self-generation of energy, but this leads to an increase of electricity-related expenses. This article assesses the impact of electricity self-generation on Cameroonian industrial companies. The model described in this article is based on data collected through a survey of a representative sample of industrial companies and from numerous previous thematic and statistical studies. The results of our analyses show that expenses related to electricity in industrial companies in Cameroon have increased five times due to electricity rationing and untimely power cuts. The article also suggests some solutions to improve the electricity self-generation capacity of industrial companies.

  3. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Pavan, J.; Gaelzer, R. [UFPEL, Pelotas (Brazil); Vinas, A. F. [NASA GSFC, Greenbelt, MD 20771 (United States); Yoon, P. H. [IPST, UMD, College Park, MD (United States); Ziebell, L. F., E-mail: joel.pavan@ufpel.edu.br, E-mail: rudi@ufpel.edu.br, E-mail: adolfo.vinas@nasa.gov, E-mail: yoonp@umd.edu, E-mail: luiz.ziebell@ufrgs.br [UFRGS, Porto Alegre (Brazil)

    2013-06-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  4. Self-generated magnetic fields and energy transport by ultra-intense laser-plasma interaction

    International Nuclear Information System (INIS)

    Abudurexiti, A.; Tuniyazi, P.; Wang Qian

    2011-01-01

    The electromagnetic instability (Weibel instability) and its mechanism in ultra-intense laser-plasma interactions are studied by using three-dimensional particle-in-cell simulations. The transport of energy in electron thermal conduction is analyzed by the Spitzer-Harm theory, and the election's vertical pyrogenation phenomenon that resulted from anisotropic heating of laser is observed. The results indicate that the strong magnetic field excited by Weibel instability makes the electron beam deposit its energy within a very short distance, and it restrains the electron thermal flux formed when the laser ponderomotive force bursts through the electron. With the increase of the self-generated magnetic field, the electron will be seized by the wave of magnetic field, and the transport of heat will be restricted. (authors)

  5. Determination of self generated magnetic field and the plasma density using Cotton Mouton polarimetry with two color probes

    Directory of Open Access Journals (Sweden)

    Joshi A.S.

    2013-11-01

    Full Text Available Self generated magnetic fields (SGMF in laser produced plasmas are conventionally determined by measuring the Faraday rotation angle of a linearly polarized laser probe beam passing through the plasma along with the interferogram for obtaining plasma density. In this paper, we propose a new method to obtain the plasma density and the SGMF distribution from two simultaneous measurements of Cotton Mouton polarimetry of two linearly polarized probe beams of different colors that pass through plasma in a direction normal to the planar target. It is shown that this technique allows us to determine the distribution of SGMF and the plasma density without doing interferometry of laser produced plasmas.

  6. Frequency up-conversion and spectral breaking of a high power microwave pulse propagation in a self-generated plasma

    International Nuclear Information System (INIS)

    Kuo, S.P.; Ren, A.

    1993-01-01

    The main concern of the propagation of high power microwave pulse is the energy loss of the pulse before reaching the destination. The loss is caused by self-generated plasma. There are two processes which are responsible for the energy loss (so called tail erosion). They are collisional damping and cutoff reflection. In very high power region, the cutoff reflection is much more severe than the collisional damping. A frequency up-conversion process may help to avoid the cutoff reflection of powerful electromagnetic pulse propagating in a self-generated plasma. Both chamber experiments and numerical simulation are performed. When the field amplitude only slightly exceeds the breakdown threshold field of the background gas, the result shows that the carrier frequency ω of the pulse shifts upward during the growth of local plasma frequency ωpe 2 . Thus, the self-generated plasma remains underdense to the pulse. However, the spectrum of the pulse starts to break up into two major peaks when the amplitude of the pulse is further increased. The frequency of one of the peaks is lower than the original carrier frequency and that of the other peak is higher than the original carrier frequency. These phenomena are observed both experimentally and numerically. The frequency down shift result is believed to be caused by damping mechanisms. Good agreement between the experimental results and the numerical simulation is obtained

  7. Observation of Self-Generated Flows in Tokamak Plasmas with Lower-Hybrid-Driven Current

    International Nuclear Information System (INIS)

    Ince-Cushman, A.; Rice, J. E.; Reinke, M.; Greenwald, M.; Wallace, G.; Parker, R.; Fiore, C.; Hughes, J. W.; Bonoli, P.; Shiraiwa, S.; Hubbard, A.; Wolfe, S.; Hutchinson, I. H.; Marmar, E.; Bitter, M.; Wilson, J.; Hill, K.

    2009-01-01

    In Alcator C-Mod discharges lower hybrid waves have been shown to induce a countercurrent change in toroidal rotation of up to 60 km/s in the central region of the plasma (r/a∼<0.4). This modification of the toroidal rotation profile develops on a time scale comparable to the current redistribution time (∼100 ms) but longer than the energy and momentum confinement times (∼20 ms). A comparison of the co- and countercurrent injected waves indicates that current drive (as opposed to heating) is responsible for the rotation profile modifications. Furthermore, the changes in central rotation velocity induced by lower hybrid current drive (LHCD) are well correlated with changes in normalized internal inductance. The application of LHCD has been shown to generate sheared rotation profiles and a negative increment in the radial electric field profile consistent with a fast electron pinch

  8. Study of electric field pulsation in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S; Itoh, K

    2011-01-01

    A model for the experimental results of the periodic oscillation of the electric field, so-called the electric field pulsation, observed in the Compact Helical Device (Fujisawa et al 1998 Phys. Rev. Lett. 81 2256) and the Large Helical Device (Shimizu et al 2010 Plasma Fusion Res. 5 S1015) is presented. A self-generated oscillation of the radial electric field is shown as the simulation result in helical plasmas. The reduction of the anomalous transport diffusivity in the core region is observed due to the strong shear of the radial electric field when the positive electric field is shown in the core region in the periodic oscillation of E r . Two different time scales are found in the self-generated oscillation, which are the transport time scale and the fast time scale at the transition of the radial electric field. This oscillation because of the hysteresis characteristic is attributed to the electric field pulsation observed in helical plasmas. The parameter region of the condition for the self-generated oscillation is derived. It is shown that the multiple solutions of the radial electric field for the ambipolar condition are necessary but not sufficient for obtaining the self-generated oscillation.

  9. Using self-generated harmonics as a diagnostic of high intensity laser-produced plasmas

    International Nuclear Information System (INIS)

    Krushelnick, K; Watts, I; Tatarakis, M; Gopal, A; Wagner, U; Beg, F N; Clark, E L; Clarke, R J; Dangor, A E; Norreys, P A; Wei, M S; Zepf, M

    2002-01-01

    The interaction of high intensity laser pulses (up to I∼10 20 W cm -2 ) with plasmas can generate very high order harmonics of the laser frequency (up to the 75th order have been observed). Measurements of the properties of these harmonics can provide important insights into the plasma conditions which exist during such interactions. For example, observations of the spectrum of the harmonic emission can provide information of the dynamics of the critical surface as well as information on relativistic non-linear optical effects in the plasma. However, most importantly, observations of the polarization properties of the harmonics can provide a method to measure the ultra-strong magnetic fields (greater than 350 MG) which can be generated during these interactions. It is likely that such techniques can be scaled to provide a significant amount of information from experiments at even higher intensities

  10. Empirical Investigation of Electricity Self-Generation in a Lubricated Sliding–Rolling Contact

    Energy Technology Data Exchange (ETDEWEB)

    Ščepanskis, Mihails; Gould, Benjamin; Greco, Aaron

    2017-07-20

    The paper reports the empirical observations of voltage generation in a lubricated tribocontact with different oils altering load, sliding and temperature. The investigation is done in the context of research of the root cause of white etching cracks (WEC) failure in bearings. Tested oils of different additive packages found completely different electrical behavior. The oil, which is known to produce WECs in laboratory tests, demonstrated non-zero voltage generation

  11. Temporal behaviour of self generated magnetic field and its influence on inhibition of thermal flux in ICF plasma

    International Nuclear Information System (INIS)

    Jha, L.N.

    1989-06-01

    The self generated magnetic field of megagauss order is reported to play a crucial role in ICF target designs because of its strong influence on the transport of energy from the critical density region to the ablation layer. The inhibition of the thermal flux due to such a field, thus, affects the whole of the other phenomenon of ICF. The knowledge of the proper variation of the magnetic field may help in assigning the existing controversial value of flux limit, f. Many papers dealing with the spatial variation of such a field exist and are well documented but the study on the variation of self generated field with time is rare. Here, the spatial variation of the megagauss field generated in the corona of a wire target irradiated by a laser as well as a model to study the temporal nature of the B-field at the peak have been obtained by solving the self inhibited diffusion which is regarded as the most dominant mechanism by which the thermal transport is influenced. The field exists for about ten nanoseconds even after the laser is switched off. The ratio of the two components of the thermal conductivity is also plotted against time and shows the inhibition. So, a track on the B-field variation both in space and time is necessary to keep for at least a few nanoseconds for computation of f. (author). 19 refs, 4 figs

  12. Theory and experimental show up of axial magnetic fields self-generated in dense laser-produced plasmas

    International Nuclear Information System (INIS)

    El Tamer, M.

    1986-09-01

    The work presented in this thesis concerns the magnetic fields generated in laser produced plasma. A summary of the theoretical and experimental studies concerning the toroidal magnetic fields and realised by different groups of research is presented. Then, we present our original contribution on the generation of axial magnetic fields by the dynamo effect. The experimental work for the detection of magnetic field is based on the Faraday rotation and Zeeman effects. The experimental diagrams are detailed and discussed. The experimental results are presented and compared to the theory. Finaly, we present some consequences of the generation of the axial magnetic fields in laser produced plasma as a discussion of the thermal conductivity [fr

  13. The detailed analysis of the spray time effects of the aluminium coating using self-generated atmospheric plasma spray system on the microstructure and corrosion behaviour

    Directory of Open Access Journals (Sweden)

    Sh. Khandanjou

    Full Text Available In the present paper our aim is to investigate the effect of the spray time of the aluminium coated layers on the microstructure and corrosion behaviour. For this purpose we use the self-generated atmospheric plasma spray system for coating of aluminium on the carbon steel substrate. The different thicknesses of coating are created. To evaluate this effect we use the several analyses such as X-ray diffraction, scanning electron microscope, Micro hardness analysis by Vickers method, Adhesion strength analysis and electrochemical polarization test. The results are very interesting and show that due to low porosity, thicker layers are more homogeneous. The nanoparticles are observed in the thicker layers. The micro hardness tests show that the thicker layers have the better micro hardness value. Next, the adhesion strength tests illustrate that the highest adhesion strength are for longer spray times. On the other hand, the corrosion resistance behaviour of the coating is investigated by electrochemical polarization test. It is shown that the corrosion resistance increases by increasing the thickness due to low percentage of porosity. Keywords: Plasma spray, Thickness, Aluminium, Micro hardness, Corrosion resistance

  14. Self-generated zonal flows in the plasma turbulence driven by trapped-ion and trapped-electron instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Drouot, T.; Gravier, E.; Reveille, T.; Collard, M. [Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine, 54 506 Vandoeuvre-lès-Nancy Cedex (France)

    2015-10-15

    This paper presents a study of zonal flows generated by trapped-electron mode and trapped-ion mode micro turbulence as a function of two plasma parameters—banana width and electron temperature. For this purpose, a gyrokinetic code considering only trapped particles is used. First, an analytical equation giving the predicted level of zonal flows is derived from the quasi-neutrality equation of our model, as a function of the density fluctuation levels and the banana widths. Then, the influence of the banana width on the number of zonal flows occurring in the system is studied using the gyrokinetic code. Finally, the impact of the temperature ratio T{sub e}/T{sub i} on the reduction of zonal flows is shown and a close link is highlighted between reduction and different gyro-and-bounce-average ion and electron density fluctuation levels. This reduction is found to be due to the amplitudes of gyro-and-bounce-average density perturbations n{sub e} and n{sub i} gradually becoming closer, which is in agreement with the analytical results given by the quasi-neutrality equation.

  15. Electric currents in cosmic plasmas

    International Nuclear Information System (INIS)

    Alfven, H.

    1977-05-01

    Since the beginning of the century physics has been dualistic in the sense that some phenomena are described by a field concept, others by a particle concept. This dualism is essential also in the physics of cosmical plasmas: some phenomena should be described by a magnetic field formalism, others by an electric current formalism. During the first period of evolution of cosmic plasma physics the magnetic field aspect has dominated, and a fairly exhaustive description has been given of those phenomena--like the propagation of waves--which can be described in this way. We have now entered a second period which is dominated by a systematic exploration of the particle (or current) aspect. A survey is given of a number of phenomena which can be understood only from the particle aspect. These include the formation of electric double layers, the origin of explosive events like magnetic substorms and solar flares, and further, the transfer of energy from one region to another. A useful method of exploring many of these phenomena is to draw the electric circuit in which the current flows and study its properties. A number of simple circuits are analyzed in this way. (author)

  16. Electric fields in plasmas under pulsed currents

    International Nuclear Information System (INIS)

    Tsigutkin, K.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Y.; Fruchtman, A.; Commisso, R. J.

    2007-01-01

    Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for three-dimensional spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously

  17. Electric properties of weakly nonideal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, K; Radtke, R

    1984-01-01

    The progress in theory as well as in diagnostics and measurement during the last fifteen years is reviewed. Starting from the transport theory of ideal plasmas physically justified corrections are introduced which allow the quantitative calculation of the transport properties of weakly nonideal plasmas. Essential coefficients and numerical data of the electrical conductivity for plasmas of technical importance are given in tables and diagrams.

  18. On the electric and magnetic field generation in expanding plasmas

    International Nuclear Information System (INIS)

    Gielen, H.J.G.

    1989-01-01

    This thesis deals with the generation of electric and magnetic fields in expanding plasmas. The theoretical model used to calculate the different field quantities in such plasmas is discussed in part 1 and is in fact an analysis of Ohm's law. A general method is given that decomposes each of the forces terms in Ohm's law in a component that induces a charge separation in the plasma and in a component that can drive current. This decomposition is unambiguous and depends upon the boundary conditions for the electric potential. It is shown that in calculating the electromagnetic field quantities in a plasma that is located in the vicinity of a boundary that imposes constraints on the electric potential, Ohm's law should be analyzed instead of the so-called induction equation. Three applications of the model are presented. A description is given of the unipolar arc discharge where both plasma and sheath effects have been taken into account. Secondly a description is presented of the plasma effects of a cathode spot. The third application of the model deals with the generation of magnetic fields in laser-produced plasmas. The second part of this thesis describes the experiments on a magnetized argon plasma expanding from a cascaded arc. With the use of spectroscopic techniques the electron density, ion temperature and the rotation velocity profiles of the ion gas have been determined. The magnetic field generated by the plasma has been measured with the use of the Zeeman effect. Depending on the channel diameter of the nozzle of the cascaded arc, self-generated magnetic fields with axial components of the order of 1% of the externally applied mangetic field have been observed. From the measured ion rotation it has been concluded that this magnetic field is mainly generated by azimuthal electron currents. The corresponding azimuthal current density is of the order of 15% of the axial current density. The observed ion rotation is caused by electron-ion friction. (author

  19. Plasma diagnostics by means of electric probes

    International Nuclear Information System (INIS)

    Colunga S, S.

    1991-04-01

    In this work a summary of the classical theoretical models to interpret the characteristic curve of a Langmuir electric probe placed in a plasma without magnetic field and with the one is made. The methodology for the electron temperature calculation and the density of the plasma in both cases is given, starting from the characteristic curve of the probe, as well as the approaches for the correct application of this diagnostic method of the plasma. (Author)

  20. Electrical and thermal conductivities in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  1. Electrical model of cold atmospheric plasma gun

    Science.gov (United States)

    Slutsker, Ya. Z.; Semenov, V. E.; Krasik, Ya. E.; Ryzhkov, M. A.; Felsteiner, J.; Binenbaum, Y.; Gil, Z.; Shtrichman, R.; Cohen, J. T.

    2017-10-01

    We present an analytical model of cold atmospheric plasma formed by a dielectric barrier discharge (DBD), which is based on the lumped and distributed elements of an equivalent electric circuit of this plasma. This model is applicable for a wide range of frequencies and amplitudes of the applied voltage pulses, no matter whether or not the generated plasma plume interacts with a target. The model allows quantitative estimation of the plasma plume length and the energy delivered to the plasma. Also, the results of this model can be used for the design of DBD guns which efficiently generate cold atmospheric plasma. A comparison of the results of the model with those obtained in experiments shows a fairly good agreement.

  2. Shock wave compression and self-generated electric field repolarization in ferroelectric ceramics Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3

    Science.gov (United States)

    Jiang, Dongdong; Du, Jinmei; Gu, Yan; Feng, Yujun

    2012-03-01

    The shock wave induced depoling current of Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3 ceramics was investigated with a system composed of a resistive load and an unpoled ceramic. Disparity in the depoling current was explained by considering the drawing charge effect of unpoled ceramic. The drawing effect for poled ceramics was analysed by developing a model incorporating a time- and electric-field-dependent repolarization. This model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. This work indicates that both the repolarization of uncompressed ceramics caused by the self-generated electric field and depolarization of compressed ceramics caused by the shock wave govern the output current.

  3. Shock wave compression and self-generated electric field repolarization in ferroelectric ceramics Pb0.99[(Zr0.90Sn0.10)0.96Ti0.04]0.98Nb0.02O3

    International Nuclear Information System (INIS)

    Jiang Dongdong; Du Jinmei; Gu Yan; Feng Yujun

    2012-01-01

    The shock wave induced depoling current of Pb 0.99 [(Zr 0.90 Sn 0.10 ) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics was investigated with a system composed of a resistive load and an unpoled ceramic. Disparity in the depoling current was explained by considering the drawing charge effect of unpoled ceramic. The drawing effect for poled ceramics was analysed by developing a model incorporating a time- and electric-field-dependent repolarization. This model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. This work indicates that both the repolarization of uncompressed ceramics caused by the self-generated electric field and depolarization of compressed ceramics caused by the shock wave govern the output current. (paper)

  4. Plasma instabilities in high electric fields

    DEFF Research Database (Denmark)

    Morawetz, K.; Jauho, Antti-Pekka

    1994-01-01

    expression is derived for the nonequilibrium dielectric function epsilon(K, omega). For certain values of momenta K and frequency omega, Imepsilon(K, omega) becomes negative, implying a plasma instability. This new instability exists only for strong electric fields, underlining its nonequilibrium origin....

  5. 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

  6. Evaluations of electric field in laser-generated pulsed plasma

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Gammino, S.; Láska, Leoš; Krása, Josef; Rohlena, Karel; Wolowski, J.

    2006-01-01

    Roč. 56, Suppl. B (2006), B580-B585 ISSN 0011-4626. [Symposium on Plasma Physics and Technology /22./. Prague, 26.06.2006-29.06.2006] Institutional research plan: CEZ:AV0Z10100523 Keywords : electric field in plasma * debye length * plasma temperature * plasma density Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.568, year: 2006

  7. Plasma Confinement in the UCLA Electric Tokamak.

    Science.gov (United States)

    Taylor, Robert J.

    2001-10-01

    The main goal of the newly constructed large Electric Tokamak (R = 5 m, a = 1 m, BT 8 x 10^12 cm-3 when there is no MHD activity. The electron temperature, derived from the plasma conductivity is > 250 eV with a central electron energy confinement time > 350 msec in ohmic conditions. The sawteeth period is 50 msec. Edge plasma rotation is induced by plasma biasing via electron injection in an analogous manner to that seen in CCT(R.J. Taylor, M.L. Brown, B.D. Fried, H. Grote, J.R. Liberati, G.J. Morales, P. Pribyl, D. Darrow, and M. Ono. Phys. Rev Lett. 63 2365 1989.) and the neoclassical bifurcation is close to that described by Shaing et al(K.C. Shaing and E.C. Crume, Phys. Rev. Lett. 63 2369 (1989).). In the ohmic phase the confinement tends to be MHD limited. The ICRF heating eliminates the MHD disturbances. Under second harmonic heating conditions, we observe an internal confinement peaking characterized by doubling of the core density and a corresponding increase in the central electron temperature. Charge exchange data, Doppler data in visible H-alpha light, and EC radiation all indicate that ICRF heating works much better than expected. The major effort is focused on increasing the power input and controlling the resulting equilibrium. This task appears to be easy since our current pulses are approaching the 3 second mark without RF heating or current drive. Our initial experience with current profile control, needed for high beta plasma equilibrium, will be also discussed.

  8. The potential role of electric fields and plasma barodiffusion on the inertial confinement fusion databasea)

    Science.gov (United States)

    Amendt, Peter; Wilks, S. C.; Bellei, C.; Li, C. K.; Petrasso, R. D.

    2011-05-01

    The generation of strong, self-generated electric fields (GV/m) in direct-drive, inertial-confinement-fusion (ICF) capsules has been reported [Rygg et al., Science 319, 1223 (2008); Li et al., Phys. Rev. Lett. 100, 225001 (2008)]. A candidate explanation for the origin of these fields based on charge separation across a plasma shock front was recently proposed [Amendt et al., Plasma Phys. Controlled Fusion 51 124048 (2009)]. The question arises whether such electric fields in imploding capsules can have observable consequences on target performance. Two well-known anomalies come to mind: (1) an observed ≈2× greater-than-expected deficit of neutrons in an equimolar D3He fuel mixture compared with hydrodynamically equivalent D [Rygg et al., Phys. Plasmas 13, 052702 (2006)] and DT [Herrmann et al., Phys. Plasmas 16, 056312 (2009)] fuels, and (2) a similar shortfall of neutrons when trace amounts of argon are mixed with D in indirect-drive implosions [Lindl et al., Phys. Plasmas 11, 339 (2004)]. A new mechanism based on barodiffusion (or pressure gradient-driven diffusion) in a plasma is proposed that incorporates the presence of shock-generated electric fields to explain the reported anomalies. For implosions performed at the Omega laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)], the (low Mach number) return shock has an appreciable scale length over which the lighter D ions can diffuse away from fuel center. The depletion of D fuel is estimated and found to lead to a corresponding reduction in neutrons, consistent with the anomalies observed in experiments for both argon-doped D fuels and D3He equimolar mixtures. The reverse diffusional flux of the heavier ions toward fuel center also increases the pressure from a concomitant increase in electron number density, resulting in lower stagnation pressures and larger imploded cores in agreement with gated, self-emission, x-ray imaging data.

  9. 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

  10. Electrical Measurements on a Moving Argon Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, A. A.M.; Howatson, A. M. [Oxford University (United Kingdom)

    1966-10-15

    Experimental current-voltage characteristic curves were obtained for a moving argon plasma at two stations in an electrically-driven 5 cm shock tube. The standard energy was 1 kj and the base pressure 10 torr, giving a shock of about Mach 4. The measurements were made on the highly-ionized driver gas which followed the shock at speeds between 800 and 1100 m/sec. Two types of electrode were used. One comprised circular solid electrodes of aluminium, molybdenum or stainless steel so machined as to be quite flush with the tube wall; the other comprised filaments of tungsten wire which were immersed in the free stream and could be used cold or heated for thermionic emission. Characteristics were obtained both for applied voltages and for MHD-generated voltages; for the latter a magnetic field of good uniformity up to 0.9 Wb/m{sup 2} was used. The results were always markedly dependent on the surface condition of the electrodes. For consistent results the flush electrodes had to be cleaned carefully by hand after every third discharge, while the filament electrodes were thermionically cleaned before every discharge. In general the cold electrode characteristics for applied voltage showed three distinct regions: a current increase such as would be expected from a double probe; a saturation region; and a linear increase, in order of increasing voltage. For the flush electrodes another apparent saturation was found before, finally, the transition to an arc-type discharge. The first saturation current for flush electrodes corresponded to a random ion current much less than that estimated to exist away from the tube walls, as is expected from a consideration of diffusion through a boundary layer. The value of the current varied somewhat with the electrode material. For the cold filaments, the saturation current density was of the same order as for the flush electrodes. From the linear region of the curves, an effective plasma conductivity was obtained. For comparison, the

  11. Initial plasma production by induction electric field on QUEST tokamak

    International Nuclear Information System (INIS)

    Hasegawa, Makoto; Nakamura, Kazuo; Sato, Kohnosuke

    2007-01-01

    Induction electric field by center solenoid coil plays a roll to produce initial plasma. According to Townsend avalanche theory, minimum electric field for plasma breakdown depends on neutral gas pressure and connection length. On QUEST spherical tokamak, a connection length is evaluated as 966m on null point neighborhood with coil current ratio I PF26 /I CS =0.1, and induction electric field considering eddy current of vacuum vessel is evaluated as about 0.1 V/m on null point neighborhood. With Townsend avalanche theory, these values manage to produce initial plasma on QUEST. (author)

  12. 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)

  13. ELECTRIC PROBE INVESTIGATION OF ARC ANODE REGION IN PLASMA TORCH

    Czech Academy of Sciences Publication Activity Database

    Chumak, Oleksiy; Hrabovský, Milan; Kavka, Tetyana

    2006-01-01

    Roč. 10, č. 4 (2006), s. 515-524 ISSN 1093-3611. [High technology plasma processes. Saint-Petersburg, 27.5.2006-4.6.2006] R&D Projects: GA ČR GA202/05/0669 Institutional research plan: CEZ:AV0Z20430508 Keywords : plasma torch * arc * anode attachment * restrike * electric probes Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.343, year: 2006

  14. Resistivity of flame plasma in an electric field

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1989-01-01

    A generalized Ohm's law is obtained for a flame plasma in an electric field for the study of arc resistivity in an electromagnetic launcher (EML). The effective resistivity of flame plasma is reduced by the source, which suggests the injection of premixed combustible fuel into the arc plasma in EML in order to reduce the electron energy of the arc. The reduction of electron energy in the arc is desirable to minimize the damage of electrodes in EML. (author)

  15. Effects of pulsed electric field on ULQ and RFP plasmas

    International Nuclear Information System (INIS)

    Watanabe, M.; Saito, K.; Suzuki, T.

    1997-01-01

    Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)

  16. Electrical characteristics of a small plasma focus device

    International Nuclear Information System (INIS)

    Choi, P.; Favre, M.; Silva, P.; Chuaqui, H.; Wyndham, E.

    1996-01-01

    Efficient plasma focus operation relies on uniform initial breakdown across the insulator surface. The basic plasma focus electric circuit is discussed in order to highlight circuit modifications that produce high voltage oscillation at the initial breakdown time. Superimposed on the main discharge voltage, such oscillating voltage has been found in real systems to enhance the initial gas breakdown by localizing the initial current path across the insulator surface. PSPICE circuit simulations are compared with electric signals from different operational plasma focus devices. (author). 3 figs., 7 refs

  17. Electrical disruption in toroidal plasma of hydrogen

    International Nuclear Information System (INIS)

    Roberto, M.; Silva, C.A.B.; Goes, L.C.S.; Sudano, J.P.

    1991-01-01

    The initial phase of ionization of a toroidal plasma produced in hydrogen was investigated using zero-dimensional model. The model describes the temporal evolution of plasma by spatial medium of particle density and temperature, on whole plasma volume. The energy and particle (electrons and ions) balance equations are considered. The electron loss is due to ambipolar diffusion in the presence of magnetic field. The electron energy loss involves ionization, Coulomb interaction and diffusion. The ohmic heating converter gives the initial voltage necessary to disruption. (M.C.K.)

  18. Detection of electric field around field-reversed configuration plasma

    International Nuclear Information System (INIS)

    Ikeyama, Taeko; Hiroi, Masanori; Nogi, Yasuyuki; Ohkuma, Yasunori

    2010-01-01

    Electric-field probes consisting of copper plates are developed to measure electric fields in a vacuum region around a plasma. The probes detect oscillating electric fields with a maximum strength of approximately 100 V/m through a discharge. Reproducible signals from the probes are obtained with an unstable phase dominated by a rotational instability. It is found that the azimuthal structure of the electric field can be explained by the sum of an n=2 mode charge distribution and a convex-surface electron distribution on the deformed separatrix at the unstable phase. The former distribution agrees with that anticipated from the diamagnetic drift motions of plasma when the rotational instability occurs. The latter distribution suggests that an electron-rich plasma covers the separatrix.

  19. Plasma diagnostics by means of electric probes; Diagnostico del plasma por medio de sondas electricas

    Energy Technology Data Exchange (ETDEWEB)

    Colunga S, S

    1991-04-15

    In this work a summary of the classical theoretical models to interpret the characteristic curve of a Langmuir electric probe placed in a plasma without magnetic field and with the one is made. The methodology for the electron temperature calculation and the density of the plasma in both cases is given, starting from the characteristic curve of the probe, as well as the approaches for the correct application of this diagnostic method of the plasma. (Author)

  20. Dielectric permittivity of a plasma in an external electric field

    International Nuclear Information System (INIS)

    Schweigert, V.A.

    2001-01-01

    The ion contribution to the dielectric function of a plasma in an external electric field is determined by applying a kinetic approach to the ions in a parent gas in which the main mechanism for ion scattering is resonant charge exchange. The ion scattering frequency is assumed to be constant

  1. Control of radial electric field in torus plasma

    International Nuclear Information System (INIS)

    Ida, K.; Idei, H.; Sanuki, H.

    1994-09-01

    The radial electric fields is controlled by changing the direction of neutral beam from co to counter to plasma current in tokamak, while it is controlled by the 2nd harmonic ECH and NBI and pellet injection in heliotron/torsatron. (author)

  2. Get rid of it: To what extent might improved reliability reduce self-generation in Nigeria?

    International Nuclear Information System (INIS)

    Oseni, Musiliu O.

    2016-01-01

    Despite the global concerns surrounding the threats of climate change to both human health and sustainable environments, gasoline- or diesel-powered generators with non-negligible emissions have become a popular choice among Nigerian households due to the poor publicly provided electricity. This study examines the extent to which an improvement in publicly supplied electricity may reduce backup generation and, by implication, reduce emissions from Nigerian homes. The results from a random-effects probit analysis reveal that, although improved electricity service quality would significantly reduce self-generation, self-generation would continue in the country, especially among rich and educated households. The study concludes by highlighting the policy implications of the findings. - Highlights: •We study how improved electricity supply might reduce self-generation in Nigeria. •Households use their generators less than 40% of times they suffer outages. •Improved service quality would significantly reduce self-generation. •However, self-generation would continue among rich and educated households. •Import tariff and pollution tax can be used to further reduce self-generation.

  3. Electric-Arc Plasma Installation for Preparing Nanodispersed Carbon Structures

    International Nuclear Information System (INIS)

    Stefanov, P.; Garlanov, D.; Vissokov, G.

    2008-01-01

    An electric-arc plasma installation operated in the hidden anode arrangement is constructed and used for the preparation of carbon nanostructures. A contracted plasma arc generated by a plasma torch using an inert gas is used as heat source. The average mass temperature of arc is higher than 10 4 K, while its power density, which is directly transferred onto the electrode (anode), is ∼ 2 kW/mm 2 . The anode contact area formed on the electrode moves against the arc by way of shifting the electrode and is hidden completely in the interior of plasma gas stream moving towards it. As a result of both the direct plasma attack and the opposite movement of streams in the hidden anode contact area, a temperature higher than 6000 K is reached. Thus, intensive vaporization takes place, which forms a saturated plasma-gas-aerosol phase of the initial material of electrode (anode). This gas phase is mixed in and carried by the plasma stream. Over that mixed plasma stream, a controlled process of quenching (fixation) is carried out by twisted turbulent fluid streams. After the fixation, the resultant carbon nano-structures are caught by a filter and collected in a bunker.

  4. Time dependent convection electric fields and plasma injection

    International Nuclear Information System (INIS)

    Kaye, S.M.; Kivelson, M.G.

    1979-01-01

    Large-scale electric fields associated with storms or substorms are responsible for inward convection and energization of plasma sheet plasma. Calculations based on steady state convection theory show that the response to such electric fields qualitatively accounts for many features of the injected particle distribution, but quantitative agreement with the theory has not yet been obtained. It is known that the predictions can be improved by introducing the concept of convection in response to a time dependent electric field. On the other hand, time dependent calculations are sensitive to the choice of initial conditions, and most models have failed to incorporate these conditions in a realistic and self-consistent manner. In this paper we present a more complete model consisting of realisic initial conditions and time dependent convection to explain a typical substorm-associated electron injection event. We find very good agreement between the observed electron flux changes and those predicted by our model

  5. Flowing Plasma Interaction with an Electric Sail Tether Element

    Science.gov (United States)

    Schneider, Todd; Vaughn, Jason; Wright, Kenneth; Anderson, Allen; Stone, Nobie

    2017-01-01

    Harnessing the power of the solar wind, an Electric Sail, or E-sail, is a relatively new concept that promises to deliver high speed propellant-less propulsion. The electric sail is an invention made in 2006 at the Kumpula Space Centre in Finland by Pekka Janhunen [Janhunen and Sandroos, 2007]. At its core, an electric sail utilizes multiple positively biased tethers which exchange momentum with solar wind protons via the repelling electric field established around each tether, in other words, by reflecting the solar wind protons. Recognizing the solar wind is a plasma, the effective repelling area of each tether is increased significantly by the formation a plasma sheath around each tether. Fig. 1 shows schematically a spacecraft employing an electric sail. The positive voltage bias (greater than10kV) applied to each tether naturally results in electron collection. Therefore, the electric sail concept necessarily includes an electron source (electron gun) to return collected electrons to space and maintain the positive bias of the tether system.

  6. Time development of electric fields and currents in space plasmas

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-05-01

    Full Text Available Two different approaches, referred to as Bu and Ej, can be used to examine the time development of electric fields and currents in space plasmas based on the fundamental laws of physics. From the Bu approach, the required equation involves the generalized Ohm's law with some simplifying assumptions. From the Ej approach, the required equation can be derived from the equation of particle motion, coupled self-consistently with Maxwell's equation, and the definition of electric current density. Recently, some strong statements against the Ej approach have been made. In this paper, we evaluate these statements by discussing (1 some limitations of the Bu approach in solving the time development of electric fields and currents, (2 the procedure in calculating self-consistently the time development of the electric current in space plasmas without taking the curl of the magnetic field in some cases, and (3 the dependency of the time development of magnetic field on electric current. It is concluded that the Ej approach can be useful to understand some magnetospheric problems. In particular, statements about the change of electric current are valid theoretical explanations of change in magnetic field during substorms.

  7. Experiments on plasma turbulence induced by strong, steady electric fields

    International Nuclear Information System (INIS)

    Hamberger, S.M.

    1975-01-01

    The author discusses the effect of applying a strong electric field to collisionless plasma. In particular are compared what some ideas and prejudices lead one to expect to happen, what computer simulation experiments tell one ought to happen, and what actually does happen in two laboratory experiments which have been designed to allow the relevant instability and turbulent processes to occur unobstructed and which have been studied in sufficient detail. (Auth.)

  8. Electric discharge plasmas influence attachment of cultured CHO k1 cells

    NARCIS (Netherlands)

    Kieft, I.E.; Broers, J.L.V.; Caubet-Hilloutou, V.; Slaaf, D.W.; Ramaekers, F.C.S.; Stoffels - Adamowicz, E.

    2004-01-01

    Non-thermal plasmas can be generated by electric discharges in gases. These plasmas are reactive media, capable of superficial treatment of various materials. A novel non-thermal atmospheric plasma source (plasma needle) has been developed and tested. Plasma appears at the end of a metal pin as a

  9. 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)

  10. Electrical properties of a co-axial plasma gun

    International Nuclear Information System (INIS)

    Allam, T.M.Y.

    1997-01-01

    The main interest of this work is to study the power discharge of capacitor bank through a coaxial electrodes system. Such arrangement is called the coaxial gun or coaxial accelerator. It is used in jet propulsion and in triggering of discharge in turbo engines or in plasma combustion arrangement. The main goal is to find out the efficiency of the system in both cases. coaxial plasma gun system has been constructed for this course of study. The plasma gun system consists of the plasma gun tube and the discharge chamber, the capacitor bank, the triggering system the vacuum system, the power supply, and safety and dumping system. Simple and efficient diagnostic techniques were used to measure the different parameters concerning the coaxial discharge system such as the Rogowski loop, the voltage divider, the magnetic probes, the double electric probe. Results were obtained using argon gas with an operating pressure ranging from 0.1 torr to 1 torr. The peak discharge current in the first half cycle was 44 K A with rise time of 6.25 μs for a bank charging voltage of 10 kv and gas pressure of 0.9 torr. 4-26 figs., 4-8 tabs., 33 refs

  11. Electron-Beam Produced Air Plasma: Optical and Electrical Diagnostics

    Science.gov (United States)

    Vidmar, Robert; Stalder, Kenneth; Seeley, Megan

    2006-10-01

    High energy electron impact excitation is used to stimulate optical emissions that quantify the measurement of electron beam current. A 100 keV 10-ma electron beam source is used to produce air plasma in a test cell at a pressure between 1 mTorr and 760 Torr. Optical emissions originating from the N2 2^nd positive line at 337.1 nm and the N2^+ 1^st negative line at 391.4 nm are observed. Details on calibration using signals from an isolated transmission window and a Faraday plate are discussed. Results using this technique and other electrical signal are presented.

  12. Electric field measurements on plasma bullets in N2 using four-wave mixing

    NARCIS (Netherlands)

    van der Schans, M.; Böhm, P.; Nijdam, S.; IJzerman, W.L.; Czarnetzki, U.

    2015-01-01

    Atmospheric pressure plasma jets driven by pulsed DC or kHz AC voltages typically consist of discrete guided ionisation waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated. Electric field measurements in N2

  13. Properties of partially ionized hydrogen plasmas in high electric fields

    International Nuclear Information System (INIS)

    Morawetz, K.

    1993-03-01

    In this thesis the fundamental equations of many-particle quantum-statistics of nonequilibrium are treated in respect to arbitrary high electric fields. Generalizations are found for the T-matrix approximation as well as for the shielded potential approximation valid for any field strength. These result in a non-Markovian behavior of the obtained collision integrals, also known as intra-collisional-field-effect (ICFE), and in a broadening of the energy conservation, the so-called collisional broadening (CB), caused by applied electric fields. In linear response it is shown in a new way, how the Debye-Onsager relaxation effect can be rederived from these collision integrals. Furthermore the complete quantum result is presented. Both effects, ICFE and CB, contribute to the right classical limit. The quantum result yields an surprising maximum of this field effects in dependence of the interacting mass ratio, which may be important in exciton-plasmas and semiconductors. (orig.)

  14. Alternating current electrical properties of Argon plasma treated jute

    Directory of Open Access Journals (Sweden)

    Md. Masroor Anwer

    2012-09-01

    Full Text Available Low temperature plasma (LTP treatment, a kind of environment friendly surface modification technique, was applied to biodegradable and environment friendly jute fibre with the use of nonpolymerizing gas, namely argon, at various discharge power levels and exposure times with a definite flow rate. Scanning electron microscopy (SEM microphotographs reveal that the roughness of the fibre surfaces increases with the increase of discharge power and exposure time. This is caused due to the bombardment of high energetic ions on the fibre surface and the fibres become sputtered. The capacitance and the electrical conductance of raw and LTP treated jute fibre were measured as a function of frequency at room temperature. The dielectric constant, conductivity, dielectric loss-tangent and the surface morphology of raw and LTP treated jute as a function of frequency were studied at room temperature. It was observed that for all the samples the dielectric constant almost constant at lower frequencies and then decreases gradually in the high frequency region. In addition, dielectric constant increases with the increase of plasma treatment time as well as discharge power. It is also observed for all the samples that the conductivity increases as the frequency increases with a lower slope in the low frequency region and with a higher slope in the higher frequency region. In addition, the conductivity decreases with the increase of plasma exposure time as well as discharge power. The conductivity increases with frequency due to the hopping mechanism of electrons. The dependence of the dielectric loss-tangent with frequency at different treatment times and discharge powers for all the jute samples show small relaxation peaks in the very low frequency region. The dielectric loss-tangent decreases with the increase of both plasma treatment time and discharge power. In addition, the relaxation peaks are shifted to the higher frequency region as the plasma treatment

  15. Interactions between Radial Electric Field, Transport and Structure in Helical Plasmas

    International Nuclear Information System (INIS)

    Ida, Katsumi and others

    2006-01-01

    Control of the radial electric field is considered to be important in helical plasmas, because the radial electric field and its shear are expected to reduce neoclassical and anomalous transport, respectively. Particle and heat transport, that determines the radial structure of density and electron profiles, sensitive to the structure of radial electric field. On the other hand, the radial electric field itself is determined by the plasma parameters. In general, the sign of the radial electric field is determined by the plasma collisionality, while the magnitude of the radial electric field is determined by the temperature and/or density gradients. Therefore the structure of radial electric field and temperature and density are strongly coupled through the particle and heat transport and formation mechanism of radial electric field. Interactions between radial electric field, transport and structure in helical plasmas is discussed based on the experiments on Large Helical Device

  16. High frequency electric field spikes formed by electron beam-plasma interaction in plasma density gradients

    International Nuclear Information System (INIS)

    Gunell, H.; Loefgren, T.

    1997-02-01

    In the electron beam-plasma interaction at an electric double layer the beam density is much higher than in the classical beam-plasma experiments. The wave propagation takes place along the density gradient, that is present at the high potential side of the double layer. Such a case is studied experimentally by injecting the electron beam from a plane cathode, without any grids suppressing the gradient, and by particle simulations. The high frequency field concentrates in a sharp 'spike' with a half width of the order of one wavelength. The spike is found to be a standing wave surrounded by regions dominated by propagating waves. It forms at a position where its frequency is close to the local plasma frequency. The spike forms also when the electric field is well below the threshold for modulational instability, and long before a density cavity is formed in the simulations. Particle simulations reveal that, at the spike, there is a backward travelling wave that, when it is strongly damped, accelerates electrons back towards the cathode. In a simulation of a homogeneous plasma without the density gradient no spike is seen, and the wave is purely travelling instead of standing. 9 refs

  17. Electric field spikes formed by electron beam endash plasma interaction in plasma density gradients

    International Nuclear Information System (INIS)

    Gunell, H.; Loefgren, T.

    1997-01-01

    In the electron beam endash plasma interaction at an electric double layer the beam density is much higher than in the classical beam endash plasma experiments. The wave propagation takes place along the density gradient that is present at the high potential side of the double layer. Such a case is studied experimentally by injecting the electron beam from a plane cathode, without any grids suppressing the gradient, and by particle simulations. The high frequency field concentrates in a sharp open-quotes spikeclose quotes with a half width of the order of one wavelength. The spike is found to be a standing wave surrounded by regions dominated by propagating waves. It forms at a position where its frequency is close to the local plasma frequency. The spike forms also when the electric field is well below the threshold for modulational instability, and long before a density cavity is formed in the simulations. Particle simulations reveal that, at the spike, there is a backward traveling wave that, when it is strongly damped, accelerates electrons back towards the cathode. In a simulation of a homogeneous plasma without the density gradient no spike is seen, and the wave is purely travelling instead of standing. copyright 1997 American Institute of Physics

  18. Cold atmospheric plasma jet in an axial DC electric field

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Li, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu; Keidar, Michael, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, The George Washington University, Washington, DC 20052 (United States)

    2016-08-15

    Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

  19. Relation between magnetic fields and electric currents in plasmas

    Directory of Open Access Journals (Sweden)

    V. M. Vasyliunas

    2005-10-01

    Full Text Available Maxwell's equations allow the magnetic field B to be calculated if the electric current density J is assumed to be completely known as a function of space and time. The charged particles that constitute the current, however, are subject to Newton's laws as well, and J can be changed by forces acting on charged particles. Particularly in plasmas, where the concentration of charged particles is high, the effect of the electromagnetic field calculated from a given J on J itself cannot be ignored. Whereas in ordinary laboratory physics one is accustomed to take J as primary and B as derived from J, it is often asserted that in plasmas B should be viewed as primary and J as derived from B simply as (c/4π∇×B. Here I investigate the relation between ∇×B and J in the same terms and by the same method as previously applied to the MHD relation between the electric field and the plasma bulk flow vmv2001: assume that one but not the other is present initially, and calculate what happens. The result is that, for configurations with spatial scales much larger than the electron inertial length λe, a given ∇×B produces the corresponding J, while a given J does not produce any ∇×B but disappears instead. The reason for this can be understood by noting that ∇×B≠4π/cJ implies a time-varying electric field (displacement current which acts to change both terms (in order to bring them toward equality; the changes in the two terms, however, proceed on different time scales, light travel time for B and electron plasma period for J, and clearly the term changing much more slowly is the one that survives. (By definition, the two time scales are equal at λe. On larger scales, the evolution of B (and hence also of ∇×B is governed by

  20. The electrical conductivity of a weakly non-ideal, dense plasma

    NARCIS (Netherlands)

    Rosado, R.J.; Leclair, J.; Schram, D.C.

    1977-01-01

    The electrical conductance of a non-ideal plasma was measured and compared with Spitzer's formula for ideal plasmas and a correction to this formula proposed by Rovinskii. The measured conductance proved to agree better with the Spitzer result

  1. Modular Pulsed Plasma Electric Propulsion System for Cubesats

    Science.gov (United States)

    Perez, Andres Dono; Gazulla, Oriol Tintore; Teel, George Lewis; Mai, Nghia; Lukas, Joseph; Haque, Sumadra; Uribe, Eddie; Keidar, Michael; Agasid, Elwood

    2014-01-01

    Current capabilities of CubeSats must be improved in order to perform more ambitious missions. Electric propulsion systems will play a key role due to their large specific impulse. Compared to other propulsion alternatives, their simplicity allows an easier miniaturization and manufacturing of autonomous modules into the nano and pico-satellite platform. Pulsed Plasma Thrusters (PPTs) appear as one of the most promising technologies for the near term. The utilization of solid and non-volatile propellants, their low power requirements and their proven reliability in the large scale make them great candidates for rapid implementation. The main challenges are the integration and miniaturization of all the electronic circuitry into a printed circuit board (PCB) that can satisfy the strict requirements that CubeSats present. NASA Ames and the George Washington University have demonstrated functionality and control of three discrete Micro-Cathode Arc Thrusters (CAT) using a bench top configuration that was compatible with the ARC PhoneSat Bus. This demonstration was successfully conducted in a vaccum chamber at the ARC Environmental Test Laboratory. A new effort will integrate a low power Plasma Processing Unit and two plasma thrusters onto a single printed circuit board that will utilize less than 13 U of Bus volume. The target design will be optimized for the accommodation into the PhoneSatEDISON Demonstration of SmallSatellite Networks (EDSN) bus as it uses the same software interface application, which was demonstrated in the previous task. This paper describes the design, integration and architecture of the proposed propulsion subsystem for a planned Technology Demonstration Mission. In addition, a general review of the Pulsed Plasma technology available for CubeSats is presented in order to assess the necessary challenges to overcome further development.

  2. Possibility of internal transport barrier formation and electric field bifurcation in LHD plasma

    International Nuclear Information System (INIS)

    Sanuki, H.; Itoh, K.; Yokoyama, M.; Fujisawa, A.; Ida, K.; Toda, S.; Itoh, S.-I.; Yagi, M.; Fukuyama, A.

    1999-05-01

    Theoretical analysis of the electric field bifurcation is made for the LHD plasma. For given shapes of plasma profiles, a region of bifurcation is obtained in a space of the plasma parameters. In this region of plasma parameters, the electric field domain interface is predicted to appear in the plasma column. The reduction of turbulent transport is expected to occur in the vicinity of the interface, inducing a internal transport barrier. Within this simple model, the plasma with internal barriers is predicted to be realized for the parameters of T e (0) ∼ 2 keV and n(0) ≅ 10 18 m -3 . (author)

  3. Self generation, small generation, and embedded generation issues

    International Nuclear Information System (INIS)

    2001-01-01

    The New Brunswick Market Design Committee for electric power restructuring has been directed to examine issues regarding cogeneration and small-scale, on-site generation and how they will fit within the framework of the bilateral contract market. The Committee will also have to deal with issues of generation embedded in a distribution system. The Committee has defined cogeneration as the simultaneous production of electricity and useful thermal energy. Self-generation has been defined as small-scale power generation by an end-user, while embedded generation has been defined as a generation facility that is located within a distribution utility but is not directly connected to the transmission system. The Committee has postponed its decision on whether embedded generation will be eligible to participate under the bilateral contract market for electricity. This report discusses general issues such as the physical support of generation, market support of generation, transition issues and policy issues. It also discusses generation support issues such as operating reserves, transmission tariff issues, and distribution tariffs. Market support issues such as transmission access for generation sales were also considered, along with market access for generation sales, and net metering for behind the meter generation. 7 refs., 1 tab

  4. Potential of mean force for electrical conductivity of dense plasmas

    Science.gov (United States)

    Starrett, C. E.

    2017-12-01

    The electrical conductivity in dense plasmas can be calculated with the relaxation-time approximation provided that the interaction potential between the scattering electron and the ion is known. To date there has been considerable uncertainty as to the best way to define this interaction potential so that it correctly includes the effects of ionic structure, screening by electrons and partial ionization. Current approximations lead to significantly different results with varying levels of agreement when compared to bench-mark calculations and experiments. We present a new way to define this potential, drawing on ideas from classical fluid theory to define a potential of mean force. This new potential results in significantly improved agreement with experiments and bench-mark calculations, and includes all the aforementioned physics self-consistently.

  5. Self-generated magnetic fields in direct-drive implosion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Igumenshchev, I. V.; Nilson, P. M.; Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Zylstra, A. B.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-06-15

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ∼10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ∼10{sup 15} W/cm{sup 2}. Proton radiographs show multiple ring-like structures produced by electric fields ∼10{sup 7} V/cm and fine structures from surface defects, indicating self-generated fields up to ∼3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇T{sub e} × ∇n{sub e} source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

  6. Magnetoresistive waves in plasmas

    International Nuclear Information System (INIS)

    Felber, F.S.; Hunter, R.O. Jr.; Pereira, N.R.; Tajima, T.

    1982-01-01

    The self-generated magnetic field of a current diffusing into a plasma between conductors can magnetically insulate the plasma. Propagation of magnetoresistive waves in plasmas is analyzed. Applications to plasma opening switches are discussed

  7. Effects of applied dc radial electric fields on particle transport in a bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1978-01-01

    The influence of applied dc radial electric fields on particle transport in a bumpy torus plasma is studied. The plasma, magnetic field, and ion heating mechanism are operated in steady state. Ion kinetic temperature is more than a factor of ten higher than electron temperature. The electric fields raise the ions to energies on the order of kilovolts and then point radially inward or outward. Plasma number density profiles are flat or triangular across the plasma diameter. It is suggested that the radial transport processes are nondiffusional and dominated by strong radial electric fields. These characteristics are caused by the absence of a second derivative in the density profile and the flat electron temperature profiles. If the electric field acting on the minor radius of the toroidal plasma points inward, plasma number density and confinement time are increased.

  8. 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)

  9. Electrical discharges of plasma ozonizer and its application

    Directory of Open Access Journals (Sweden)

    Tirawanichakul, S.

    2007-05-01

    Full Text Available Ozone synthesis is one of the applications of near atmospheric plasma processing. An ozone generator in this research comprised two annular cylindrical-shaped electrodes. The inner electrode was made ofstainless steel covered with the dielectric glass and the outer electrode was also made of stainless steel. The electric spacing gap was 0.0075 m and length of ozonizer was 0.21 m. Oxygen gas passing through thedischarge gap between two electrodes supplied by an alternating current (AC high voltage power supply, frequency 50 Hz, ranging of 6-10 kVAC was used for producing ozone. The amount of ozone was determinedby the KI standard method. The result showed that the concentration of ozone is proportional to the AC applied voltage. For determining effect of purified oxygen feed rate of 6-10 L/min on quantity of ozone, theresults indicated that at the volumetric flow rate of 8 L/min produced the largest amount of ozone. In addition, ozone concentration at a flow rate of 8 L/min and an electrical discharge time of 3 minutes wasapproximately determined as 41, 60, 80 and 135 mg/L at 8, 9, 10 and 11 kVAC, respectively. Moreover, study of dye wastewater of Krajud mat was proposed and treated by three different methods. Firstly, dye wastewater was solely treated by a plasma ozonation. Secondly, a combination ofozonation and alum coagulation was used for dye wastewater treatment. Finally, the combined ozonation and activated carbon adsorption were used for dye wastewater treatment. The experimental results showedthat the percentage of light absorbance reduction of pink dyed wastewater for these three different methods was about 56%, 35% and 10%, respectively compared to the reference sample. In addition, For thesemethods, the percentage of BOD of treated dye wastewater could be reduced to 64%, 54% and 46% respectively, the percentage of COD could be reduced to approximately 78%, 62% and 27%, respectively, comparedto the reference sample. In conclusion, the

  10. Electrical conductivity of the thermal dusty plasma under the conditions of a hybrid plasma environment simulation facility

    Science.gov (United States)

    Zhukhovitskii, Dmitry I.; Petrov, Oleg F.; Hyde, Truell W.; Herdrich, Georg; Laufer, Rene; Dropmann, Michael; Matthews, Lorin S.

    2015-05-01

    We discuss the inductively heated plasma generator (IPG) facility in application to the generation of the thermal dusty plasma formed by the positively charged dust particles and the electrons emitted by them. We develop a theoretical model for the calculation of plasma electrical conductivity under typical conditions of the IPG. We show that the electrical conductivity of dusty plasma is defined by collisions with the neutral gas molecules and by the electron number density. The latter is calculated in the approximations of an ideal and strongly coupled particle system and in the regime of weak and strong screening of the particle charge. The maximum attainable electron number density and corresponding maximum plasma electrical conductivity prove to be independent of the particle emissivity. Analysis of available experiments is performed, in particular, of our recent experiment with plasma formed by the combustion products of a propane-air mixture and the CeO2 particles injected into it. A good correlation between the theory and experimental data points to the adequacy of our approach. Our main conclusion is that a level of the electrical conductivity due to the thermal ionization of the dust particles is sufficiently high to compete with that of the potassium-doped plasmas.

  11. Self-generation of magnetic fields

    International Nuclear Information System (INIS)

    Dolan, T.J.

    2000-01-01

    The stars generate self-magnetic fields on large spatial scales and long time scales,and laser-produced plasmas generate intense self-magnetic fields on very short spatial and time scales. Two questions are posed : (1) Could a self-magnetic field be generated in a laboratory plasma with intermediate spatial and time scales? (2) If a self-magnetic field were generated,would it evolve towards a minimum energy state? If the answers turned out to be affirmative,then self-magnetic fields could possibly have interesting applications

  12. Electrical field excitation in non-uniform plasma by a modulated electron beam

    International Nuclear Information System (INIS)

    Anisimov, I.O.; Borisov, O.A.

    2000-01-01

    Excitation of electric fields due to a modulated electron beam in a warm non-uniform plasma is treated for weak beams in warm plasma. It is shown that the maximum electric field magnitude that is reached near the local plasma resonance point depends significantly on the direction of the electron stream motion. In collisional plasma the magnitude of the Langmuir wave that propagates to the subcritical plasma also depends on the direction of the electron stream motion. The motion of the modulated electron stream front results in beatings between oscillations on the modulation frequency and on the local electron plasma frequencies at the initial moment. Later these beatings damp in the supercritical plasma, whereas in the subcritical plasma they are transformed into spatial beatings between the field of the modulated electron stream and the excited Langmuir wave. (orig.)

  13. Influence of an External DC Electric Current on Plasma Cleaning Rate: an Application on the Enlarged Plasma-Surface Theory

    International Nuclear Information System (INIS)

    Xaplanteris, Constantine L.; Filippaki, Eleni D.

    2013-01-01

    During the last decades many researchers have been occupied with other plasma applications apart from the big challenge which the thermonuclear fusion poses. Many experiments have been carried out on the plasma behavior in contact with a solid surface; when the surface material consists of chemical compounds (e.g. oxides of metals), then the plasma chemistry takes place. The present paper contains the final experimental and theoretical work of Plasma Laboratory at “Demokritos , which consists of an elaboration of plasma sheath parameters adapted to experimental conditions, a suitable choice of plasma gases (either H 2 or N 2 ), and an electric potential current enforcement on objects. Additionally, a brief theory is given to explain the results, with a short reference to both boundary phenomena in thermonuclear reactors and low pressure plasma of glow discharges, so as to reveal the similarities and differences of these two cases. An extensive examination of the treated objects by X-ray diffraction method (XRD) gives results in agreement with the theoretical predictions. Using this improvement on plasma restoration system, (a combination of electric current on metallic object into suitable plasma), it is shown that better results can be achieved on the cleaning and conservation of archaeological objects. (plasma technology)

  14. Electric field bifurcation and transition in the core plasma of CHS

    International Nuclear Information System (INIS)

    Fujisawa, A.; Iguchi, H.; Sanuki, H.; Itoh, K.; Okamura, S.; Matsuoka, K.; Hamada, Y.; Itoh, S.-I.

    1997-01-01

    In the CHS heliotron/torsatron, dynamic phenomena associated with transitions in radial electric field were observed during combined ECH+NBI heated plasmas. The observations with high temporal resolution confirmed a nonlinear relation between radial electric field and radial current to cause these phenomena associated with electric field bifurcation. (author)

  15. 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

  16. Stabilization effect of a strong HF electrical field on beam-plasma interaction in a relativistic plasma waveguide

    International Nuclear Information System (INIS)

    El-Shorbagy, K.H.

    2000-07-01

    The influence effect of a strong HF electrical field on the excitation of surface waves by an electron beam under the development of instability of low-density electron beam passing through plane relativistic plasma is investigated. Starting from the two fluid plasma model we separate the problem into two parts. The 'temporal' (dynamical) part enables us to find the frequencies and growth rates of unstable waves. This part within the redefinition of natural (eigen) frequencies coincide with the system describing HF suppression of the Buneman instability in a uniform unbounded plasma. Natural frequencies of oscillations and spatial distribution of the amplitude of the self-consistent electrical field are obtained by solving a boundary value problem ('spatial' part) considering a specific spatial distribution of plasma density. Plasma electrons are considered to have a relativistic velocity. It is shown that a HF electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a relativistic plasma waveguide by a low-density electron beam. The region of instability only slightly narrowing and the growth rate decreases by a small parameter and this result has been reduced compared to nonrelativistic plasma. Also, it is found that the plasma electrons have not affected the solution of the space part of the problem. (author)

  17. Principles of spectroscopic diagnostics of a plasma with oscillating electric fields

    International Nuclear Information System (INIS)

    Oks, E.A.

    1986-01-01

    Three types of main principles of spectroscopic diagnosis of the plasma with quasimonochromatic electric fields (QEF) are considered. Principles based on the effects intersectionally depending on the parameters of QEF and the plasma medium are considered. Occurrence of depressions or dips in the profiles of spectral lines is the most important effect among others. Principles based on the nonlinear theory of plasma and laser sattelites of spectral lines as well as laser-spectroscopic diagnosis of QEF in the plasma are considered

  18. Electric susceptibility of a magnetized plasma under electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Kawamori, E

    2011-01-01

    This study derives the electric susceptibility tensor of a cold magnetized plasma under electromagnetically induced transparency (EIT) regime (Litvak and Tokman 2002 Phys. Rev. Lett. 88 095003, Shvets and Wurtele 2002 Phys. Rev. Lett. 89 115003) in which an intense right-hand circularly polarized pump wave is injected parallel to the background magnetic field. A dispersion relation of the wave in the electron cyclotron frequency range for an arbitrary propagation angle is obtained from this susceptibility tensor. In the case of purely parallel propagation of the probe wave, the dispersion relation obtained by Litvak, Shvets and others is recaptured. A new finding is that a stop band emerges between left-hand cutoff and upper hybrid frequencies, in which originally an extraordinary-mode (X) branch exists, in the case of perpendicular propagation to the background magnetic field under the EIT. The bandwidth of the stop band expands as the pump wave is intensified. For the situation of launching the probe wave from the high-field side in a tokamak, the accessibility of the probe wave to the region where the EIT effect appears is investigated. The EIT region which is a resonance layer created by the EIT is accessible to the probe wave, indicating the possibility of the application of EIT to control the spatial position of wave power deposition.

  19. A review of self generated B-field in ICF corona

    International Nuclear Information System (INIS)

    Jha, L.N.

    1989-07-01

    Self generated high order magnetic field in the corona of Inertial Confinement Fusion Plasma plays a very important role in the design of fusion target because of its strong influence on the transport of thermal flux from the critical density region to the ablation layer. A review of the generation of megagauss magnetic field both experimental, theoretical and simulation studies has been presented. (author). 28 refs, 5 figs, 1 tab

  20. Electrical and spectroscopic characterization of a surgical argon plasma discharge

    International Nuclear Information System (INIS)

    Keller, Sandra; Neugebauer, Alexander; Bibinov, Nikita; Awakowicz, Peter

    2013-01-01

    For electrosurgical procedures, the argon plasma coagulation (APC) discharge is a well-established atmospheric-pressure plasma tool for thermal haemostasis and devitalization of biological tissue. To characterize this plasma source, voltage-current measurements, microphotography, optical emission spectroscopy and numerical simulation are applied. Two discharge modes are established during the operation of the APC plasma source. A short transient spark discharge is ignited within the positive half period of the applied high voltage after a streamer channel connects the APC probe and the counter-electrode. During the second phase, which continues under negative high voltage, a glow discharge is stabilized in the plasma channel.

  1. Fluctuations in collisional plasma in the presence of an external electric field

    International Nuclear Information System (INIS)

    Momot, A. I.; Zagorodny, A. G.

    2011-01-01

    The theory of large-scale fluctuations in a plasma is used to calculate the correlations functions of electron and ion density with regard to particle collisions described within the Bhatnagar-Gross-Krook (BGK) model and the presence of a constant external electric field. The changes of plasma particle distribution functions due to an external electric field and their influence on the plasma dielectric response are taken into account. The dispersion relations for longitudinal waves in such a plasma are studied in details. It is shown that external electric field can lead to the ion-acoustic wave instability and anomalous growth of the fluctuation level. Detailed numerical studies of the general relations for electron number density fluctuations are performed and the effect of external electric field on the fluctuation spectra is studied.

  2. Inward transport of a toroidally confined plasma subject to strong radial electric fields

    Science.gov (United States)

    Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J.; Kim, Y.

    1977-01-01

    The paper aims at showing that the density and confinement time of a toroidal plasma can be enhanced by radial electric fields far stronger than the ambipolar values, and that, if such electric fields point into the plasma, radially inward transport can result. The investigation deals with low-frequency fluctuation-induced transport using digitally implemented spectral analysis techniques and with the role of strong applied radial electric fields and weak vertical magnetic fields on plasma density and particle confinement times in a Bumpy Torus geometry. Results indicate that application of sufficiently strong radially inward electric fields results in radially inward fluctuation-induced transport into the toroidal electrostatic potential well; this inward transport gives rise to higher average electron densities and longer particle confinement times in the toroidal plasma.

  3. 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.

  4. 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

  5. Determination of the characteristics of an electric arc plasma contaminated by vapors from insulators

    International Nuclear Information System (INIS)

    Abbaoui, M.; Cheminat, B.

    1991-01-01

    An experimental study at atmospheric pressure carried out on plasma penetrated by vapors from different industrial insulators allowed the showing of the influence of the nature of the insulator upon the characteristics of the electric arc plasma; i.e., an increase of the temperature, electron density, electric field, and extinction velocity of the arc. Measurements have been made spectrometrically and by means of probes

  6. Confinement of a neutral plasma using nested electric potential wells

    International Nuclear Information System (INIS)

    Ordonez, C.A.

    1997-01-01

    A self-consistent, two-dimensional analysis is presented on confining a region of neutral plasma with a Penning/Malmberg type plasma trap using a nested well configuration. It is found that a neutral plasma region having disparate electron and ion temperatures or having high charge state ions can be confined with static fields. For confining a neutral region comprised of electrons and equal temperature low charge state ions, a quasistatic approach appears promising. copyright 1997 American Institute of Physics

  7. Imaging axial and radial electric field components in dielectric targets under plasma exposure

    NARCIS (Netherlands)

    Slikboer, E.T.; Sobota, A.; Guaitella, O.; Garcia-Caurel, E.

    2018-01-01

    This work presents new ways to investigate the individual electric field components in a dielectric target induced by a non thermal atmospheric pressure plasma jet. Mueller polarimetry is applied to investigate electro-optic crystals under exposure of guided ionization waves produced by a plasma

  8. Power loss of an oscillating electric dipole in a quantum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ghaderipoor, L. [Department of Physics, Faculty of Science, University of Qom, 3716146611 (Iran, Islamic Republic of); Mehramiz, A. [Department of Physics, Faculty of Science, Imam Khomeini Int' l University, Qazvin 34149-16818 (Iran, Islamic Republic of)

    2012-12-15

    A system of linearized quantum plasma equations (quantum hydrodynamic model) has been used for investigating the dispersion equation for electrostatic waves in the plasma. Furthermore, dispersion relations and their modifications due to quantum effects are used for calculating the power loss of an oscillating electric dipole. Finally, the results are compared in quantum and classical regimes.

  9. Status and challenges in electrical diagnostics of processing plasmas

    DEFF Research Database (Denmark)

    Stamate, Eugen

    2014-01-01

    Dry processing based on reactive plasmas was the main driven force for micro- and recently nano-electronic industry. Once with the increasing in plasma complexity new diagnostics methods have been developed to ensure a proper process control during etching, thin film deposition, ion implantation...

  10. The measurement and analysis of electric fields in glow discharge plasmas

    International Nuclear Information System (INIS)

    Lawler, J.E.; Doughty, D.A.

    1994-01-01

    Interest in glow discharge plasmas has remained high for many decades because of their widespread application as a source of incoherent and coherent light, in plasma processing materials, in pulsed power devices, and in other technologies. Plasma etching of semiconductors and various plasma deposition process emerged as major applications during the 1980s. The technological significance of plasma processing is described in Plasma Processing of Materials. More fundamental work on glow discharges also advanced greatly during the 1980s. For example, substantial progress was made through the use of laser diagnostics to study glow discharges and as a result of the dramatically increased computing power that became available in the 1980s to model glow discharges. Many of the laser diagnostics are described in Radiative Processes in Discharge Plasmas. Kinetic theory models, in particular, became far more sophisticated and realistic during the 1980s. This article is a review of recent work that used optical diagnostics to study electric fields in glow discharge plasmas. Alternative methods for measuring electric electric fields in plasmas include electron beam deflection and electrostatic probes. Optical techniques have important advantages over these methods: They can be used at higher pressures and discharge current densities than electron beam deflection; and they are noninvasive, unlike electrostatic probes. In addition, optical techniques are usually easier to apply in a highly pure system than either of the alternative methods. 46 refs., 23 figs., 1 tab

  11. Plasma waves and electric discharges induced by a beam from a high-latitude satellite

    International Nuclear Information System (INIS)

    Kuns, G.; Koen, G.

    1985-01-01

    Using P78-2 satellite measurements of characteristics of space probe charging in synchronous orbit are carried out. A particle beam generation system including electron and ion guns was part of the satellite equipment. Electric charge analyser placed aboard the satellite in course of electron and ion beam generation recorded plasma waves and electric discharges

  12. Two dimensional analytical considerations of large magnetic and electric fields in laser produced plasmas

    International Nuclear Information System (INIS)

    Eliezer, S.; Loeb, A.

    1985-08-01

    A simple model in two dimensions is developed and solved analytically taking into account the electric and magnetic fields in laser procuded plasmas. The electric potential in this model is described by a nonlinear differential equation. The stationary solution of this model is consistent for -0.1 less than or equal to psi 6 v/cm]/[B/MGauss] approx. 1

  13. End-shorting and electric field in edge plasmas with application to field-reversed configurations

    International Nuclear Information System (INIS)

    Steinhauer, Loren C.

    2002-01-01

    The shorting of open field lines where they intersect external boundaries strongly modifies the transverse electric field all along the field lines. The modified electric field is found by an extension of the familiar Boltzmann relation for the electric potential. This leads to a prediction of the electric drift. Flow generation by electrical shorting is applied here to three aspects of elongated field-reversed configurations: plasma rotation rate; the particle-loss spin-up mechanism; and the sustainability of the rotating magnetic field current drive method

  14. The role of fluctuation-induced transport in a toroidal plasma with strong radial electric fields

    Science.gov (United States)

    Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J. Y.; Kim, Y. C.

    1981-01-01

    Previous work employing digitally implemented spectral analysis techniques is extended to demonstrate that radial fluctuation-induced transport is the dominant ion transport mechanism in an electric field dominated toroidal plasma. Such transport can be made to occur against a density gradient, and hence may have a very beneficial effect on confinement in toroidal plasmas of fusion interest. It is shown that Bohm or classical diffusion down a density gradient, the collisional Pedersen-current mechanism, and the collisionless electric field gradient mechanism described by Cole (1976) all played a minor role, if any, in the radial transport of this plasma.

  15. Effects of non-uniformities on electrical conduction in weakly ionized plasmas

    International Nuclear Information System (INIS)

    Numano, M.; Murakami, Y.; Nitta, T.

    1989-01-01

    The effect of non-uniformities on the flow of electric current in weakly ionized plasmas is investigated by taking into account the ion slip as well as the Hall current. An Ohm's law for a non-uniform plasma is derived, from which the formula previously obtained by Numano, i.e. an extension of Rosa's equation, is obtainable as a special case. Making use of this new Ohm's law, the effective electrical conductivity and the effective Hall parameter are determined for isotropically turbulent plasmas. It is found that when the ion-slip effect is absent they are in good agreement with the results obtained previously. (author)

  16. Model of an electric field produced by viscous interaction in the plasma sheet of the magnetotail

    International Nuclear Information System (INIS)

    Erkaev, N.V.

    1996-01-01

    Two-dimensional model of flow in a plasma layer of magnetotail is considered with account of low viscosity. The general Ohm's law is used for electric current. The role of viscous forces is most sufficient in boundary layers, which expand with moving away along the flow and located along the boundaries of plasma layer and solar wind. Auto model solution, describing the distribution of potential and velocity in boundary layers was obtained. The solution for boundary layers dictates boundary conditions for determination of large-scale distribution of electric potential in plasma layer. 7 refs., 4 figs

  17. Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    International Nuclear Information System (INIS)

    Gonzalez, G.; Krishnan, B.; Avellaneda, D.; Castillo, G. Alan; Das Roy, T.K.; Shaji, S.

    2011-01-01

    Cadmium sulphide (CdS) is a well known n-type semiconductor that is widely used in solar cells. Here we report preparation and characterization of chemical bath deposited CdS thin films and modification of their optical and electrical properties using plasma treatments. CdS thin films were prepared from a chemical bath containing Cadmium chloride, Triethanolamine and Thiourea under various deposition conditions. Good quality thin films were obtained during deposition times of 5, 10 and 15 min. CdS thin films prepared for 10 min. were treated using a glow discharge plasma having nitrogen and argon carrier gases. The changes in morphology, optical and electrical properties of these plasma treated CdS thin films were analyzed in detail. The results obtained show that plasma treatment is an effective technique in modification of the optical and electrical properties of chemical bath deposited CdS thin films.

  18. Modification of optical and electrical properties of chemical bath deposited CdS using plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Avellaneda, D.; Castillo, G. Alan; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P 66450 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2011-08-31

    Cadmium sulphide (CdS) is a well known n-type semiconductor that is widely used in solar cells. Here we report preparation and characterization of chemical bath deposited CdS thin films and modification of their optical and electrical properties using plasma treatments. CdS thin films were prepared from a chemical bath containing Cadmium chloride, Triethanolamine and Thiourea under various deposition conditions. Good quality thin films were obtained during deposition times of 5, 10 and 15 min. CdS thin films prepared for 10 min. were treated using a glow discharge plasma having nitrogen and argon carrier gases. The changes in morphology, optical and electrical properties of these plasma treated CdS thin films were analyzed in detail. The results obtained show that plasma treatment is an effective technique in modification of the optical and electrical properties of chemical bath deposited CdS thin films.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  20. Physical mechanism determining the radial electric field and its radial structure in a toroidal plasma

    International Nuclear Information System (INIS)

    Ida, Katsumi; Miura, Yukitoshi; Itoh, Sanae

    1994-10-01

    Radial structures of plasma rotation and radial electric field are experimentally studied in tokamak, heliotron/torsatron and stellarator devices. The perpendicular and parallel viscosities are measured. The parallel viscosity, which is dominant in determining the toroidal velocity in heliotron/torsatron and stellarator devices, is found to be neoclassical. On the other hand, the perpendicular viscosity, which is dominant in dictating the toroidal rotation in tokamaks, is anomalous. Even without external momentum input, both a plasma rotation and a radial electric field exist in tokamaks and heliotrons/torsatrons. The observed profiles of the radial electric field do not agree with the theoretical prediction based on neoclassical transport. This is mainly due to the existence of anomalous perpendicular viscosity. The shear of the radial electric field improves particle and heat transport both in bulk and edge plasma regimes of tokamaks. (author) 95 refs

  1. Modulational instability of electric helicons in a magnetized collisional plasma

    International Nuclear Information System (INIS)

    El-Ashry, M.Y.; Papuashvili, N.A.

    1987-06-01

    The interaction of a rf electromagnetic wave with a magnetized collisional plasma in the ultra-relativistic case has been investigated to show the effect of the collisions on the modulational instability growth rate. (author). 5 refs

  2. On plasma stability under anisotropic random electric field influence

    International Nuclear Information System (INIS)

    Rabich, L.N.; Sosenko, P.P.

    1987-01-01

    The influence of anisotropic random field on plasma stability is studied. The thresholds and instability increments are obtained. The stabilizing influence of frequency missmatch and external magnetic field is pointed out

  3. On the theory of the electrical field and the plasma rotation in the stellarator

    International Nuclear Information System (INIS)

    Coronado-Gallardo, M.

    1984-01-01

    In the context of neoclassical transport theory, the macroscopic torque equations for several liquids in toroidal plasmas are used with general geometry. In order to examine plasma rotation and the electrical field in equilibrium and the effect of sources of particles and pulses, the continuity and pulse balance equations are dealt with. In order to use them on the WVII-A stellarator in the Max Planck Institute for Plasma Physics, existing formulae are expanded and the viscosity tensor is calculated in the CGL form in the plateau range. General expressions for plasma speed, electrical field, plasma diffusion and current are obtained, in which the effect of the sources occurs explicitly. The theory is applied to the WVII-A stellarator, in which neutral particle injection represents one pulse source. (orig.) [de

  4. Plasma rotation and radial electric field with a density ramp in an ohmically heated tokamak

    International Nuclear Information System (INIS)

    Duval, B.P.; Joye, B.; Marchal, B.

    1991-10-01

    Measurements of toroidal and poloidal rotation of the TCA plasma with Alfven Wave Heating and different levels of gas feed are reported. The temporal evolution of the rotation was inferred from intrinsic spectral lines of CV, CIII and, using injected helium gas, from HeII. The light collection optics and line intensity permitted the evolution of the plasma rotation to be measured with a time resolution of 2ms. The rotation velocities were used to deduce the radial electric field. With Alfven heating there was no observable change of this electric field that could have been responsible for the density rise which is characteristic of the RF experiments on TCA. The behaviour of the plasma rotation with different plasma density ramp rates was investigated. The toroidal rotation was observed to decrease with increasing plasma density. The poloidal rotation was observed to follow the value of the plasma density. With hard gas puffing, changes in the deduced radial electric field were found to coincide with changes in the peaking of the plasma density profile. Finally, with frozen pellet injection, the expected increase in the radial electric field due to the increased plasma density was not observed, which may explain the poorer confinement of the injected particles. Even in an ohmically heated tokamak, the measurement of the plasma rotation and the radial electric field are shown to be strongly related to the confinement. A thorough statistical analysis of the systematic errors is presented and a new and significant source of uncertainty in the experimental technique is identified. (author) 18 figs., 18 refs

  5. Characterisation of a micro-plasma device sensor using electrical measurements and emission spectroscopy

    International Nuclear Information System (INIS)

    Mariotti, D.

    2002-04-01

    This thesis reports on research undertaken on the characterisation of a micro-plasma device to be used for gas analysis by mean of plasma emission spectroscopy. The work covers aspects related to the micro-plasma electrical and optical emission parameters, and their importance for the utilisation of the micro-plasma device in gas analysis. Experimental results have been used to analyse the fundamental micro-plasma processes and to develop a model, which could provide additional information. This dissertation contains a general literature review of topics related to plasma physics, plasma emission spectroscopy, gas analysis (chemical analysis and artificial olfaction) and other micro-plasma applications. Experimental work focuses on two main areas: electrical measurements and emission measurements. Firstly, electrical measurements are taken and interpretations are given. Where necessary, new theoretical treatments are suggested in order to describe better the physical phenomena. Plasma emission has been considered under different working conditions. This allowed the characterisation of the micro-plasma emission and also a better understanding of the micro-plasma processes. On the basis of the experimental data obtained and other assumptions a model has been developed. A computer simulation based on this model provided additional useful information on the micro- plasma behaviour. The first fundamental implication of this new research is the peculiar behaviour of the micro-plasma. This micro-plasma exhibited deviations from Paschen law and strong dependency on cathode material, which contributed to the formation of a low current stable regime. These results have been followed by physical interpretations and theoretical descriptions. The second implication is the establishment of the boundaries and of the influencing parameters for plasma emission spectroscopy as an analytical tool in this particular micro-plasma. From the applied perspective this study has shown that

  6. Thermo-structural modelling of a plasma discharge tube for electric propulsion

    International Nuclear Information System (INIS)

    Faoite, D. de; Browne, D.J.; Del Valle Gamboa, J.I.; Stanton, K.T.

    2016-01-01

    Highlights: • Thermo-structural analyses were performed for an electric propulsion space thruster. • Thermal stresses arise primarily from mismatches in thermal expansion coefficients. • Aluminium nitride is a suitable material for a plasma containment tube. • A design is presented allowing a thruster to operate at a power of at least 250 kW. - Abstract: Potential thermal management strategies for the plasma generation section of a VASIMR"® high-power electric propulsion space thruster are assessed. The plasma is generated in a discharge tube using helicon waves. The plasma generation process causes a significant thermal load on the plasma discharge tube and on neighbouring components, caused by cross-field particle diffusion and UV radiation. Four potential cooling system design strategies are assessed to deal with this thermal load. Four polycrystalline ceramics are evaluated for use as the plasma discharge tube material: alumina, aluminium nitride, beryllia, and silicon nitride. A finite element analysis (FEA) method was used to model the steady-state temperature and stress fields resulting from the plasma heat flux. Of the four materials assessed, aluminium nitride would result in the lowest plasma discharge tube temperatures and stresses. It was found that a design consisting of a monolithic ceramic plasma containment tube fabricated from aluminium nitride would be capable of operating up to a power level of at least 250 kW.

  7. The Synergistic Effect between Electrical and Chemical Factors in Plasma Gene/Molecule-Transfection

    Science.gov (United States)

    Jinno, Masafumi

    2016-09-01

    This study has been done to know what kind of factors in plasma and processes on cells promote plasma gene/molecule transfection. We have discovered a new plasma source using a microcapillary electrode which enables high transfection efficiency and high cell survivability simultaneously. However, the mechanism of the transfection by plasma was not clear. To clarify the transfection mechanisms by micro plasma, we focused on the effects of electrical (current, charge, field, etc.) and chemical (radicals, RONS, etc.) factors generated by the micro plasma and evaluated the contribution weight of three groups of the effects and processes, i.e. electrical, chemical and biochemical ones. At first, the necessity of the electrical factors was estimated by the laser produced plasma (LPP). Mouse L-929 fibroblast cell was cultured on a 96-well plate or 12-well micro slide chamber. Plasmids pCX-EGFP in Tris-EDTA buffer was dropped on the cells and they were exposed to the capillary discharge plasma (CDP) or the LPP. In the case of the CDP, the plasma was generated between the tip of the capillary electrode and the cells so that both electrical and chemical factors were supplied to the cells. In this setup, about 20% of average transfection efficiency was obtained. In the case of the LPP, the plasma was generated apart from the cells so that electrical factors were not supplied to the cells. In this setup, no transfection was observed. These results show that the electrical factors are necessary for the plasma gene transfection. Next, the necessity of the chemical factors was estimated the effect of catalase to remove H2O2 in CDP. The transfection efficiency decreased to 0.4 by scavenging H2O2 with catalase. However, only the solution of H2O2 caused no gene transfection in cells. These results shows that H2O2 is important species to cause gene/molecule transfection but still needs a synergistic effect with electrical or other chemical factors. This work was partly supported by

  8. Ion confinement and transport in a toroidal plasma with externally imposed radial electric fields

    Science.gov (United States)

    Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Kim, Y. C.; Hong, H. Y.

    1979-01-01

    Strong electric fields were imposed along the minor radius of the toroidal plasma by biasing it with electrodes maintained at kilovolt potentials. Coherent, low-frequency disturbances characteristic of various magnetohydrodynamic instabilities were absent in the high-density, well-confined regime. High, direct-current radial electric fields with magnitudes up to 135 volts per centimeter penetrated inward to at least one-half the plasma radius. When the electric field pointed radially toward, the ion transport was inward against a strong local density gradient; and the plasma density and confinement time were significantly enhanced. The radial transport along the electric field appeared to be consistent with fluctuation-induced transport. With negative electrode polarity the particle confinement was consistent with a balance of two processes: a radial infusion of ions, in those sectors of the plasma not containing electrodes, that resulted from the radially inward fields; and ion losses to the electrodes, each of the which acted as a sink and drew ions out of the plasma. A simple model of particle confinement was proposed in which the particle confinement time is proportional to the plasma volume. The scaling predicted by this model was consistent with experimental measurements.

  9. Plasma rotation by electric and magnetic fields in a discharge cylinder

    Science.gov (United States)

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

    1977-01-01

    A theoretical model for an electric discharge consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field is developed to study the rotation of the discharge plasma in the crossed electric and magnetic fields. The associated boundary-value problem for the coupled partial differential equations which describe the electric potential and the plasma velocity fields is solved in closed form. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number and the Hall coefficient. As a result of Lorentz forces, the plasma rotates with speeds as high as 1 million cm/sec around its axis of symmetry at typical conditions. As an application, it is noted that rotating discharges of this type could be used to develop a high-density plasma-ultracentrifuge driven by j x B forces, in which the lighter (heavier) ion and atom components would be enriched in (off) the center of the discharge cylinder.

  10. Effectiveness of self-generated cues in early Alzheimer's disease.

    Science.gov (United States)

    Lipinska, B; Bäckman, L; Mäntylä, T; Viitanen, M

    1994-12-01

    The ability to utilize cognitive support in the form of self-generated cues in mild Alzheimer's disease (AD), and the factors promoting efficient cue utilization in this group of patients, were examined in two experiments on memory for words. Results from both experiments showed that normal old adults as well as AD patients performed better with self-generated cues than with experimenter-provided cues, although the latter type of cues resulted in gains relative to free recall. The findings indicate no qualitative differences in patterns of performance between the normal old and the AD patients. For both groups of subjects, cue effectiveness was optimized when (a) there was self-generation activity at encoding, and (b) encoding and retrieval conditions were compatible.

  11. Investigation of Dusts Effect and Negative Ion in DC Plasmas by Electric Probes

    Science.gov (United States)

    Oh, Hye Taek; Kang, Inje; Bae, Min-Keun; Park, Insun; Lee, Seunghwa; Jeong, Seojin; Chung, Kyu-Sun

    2017-10-01

    Dust is typically negatively charged by electron attachment whose thermal velocities are fast compared to that of the heavier ions. The negatively charged particles can play a role of negative ions which affect the quasi-neutrality of background plasma. To investigate effect of metal dusts and negative ion on plasma and materials, metal dusts are injected into background Ar plasma which is generated by tungsten filament using dust dispenser on Cubical Plasma Device (CPD). The CPD has following conditions: size =24x24x24cm3, plasma source =DC filament plasma (ne 1x10x1010, Te 2eV), background gas =Ar, dusts =tungsten powder (diameter 1.89micron). The dust dispenser is developed to quantitate of metal dust by ultrasonic transducer. Electronegative plasmas are generated by adding O2 + Ar plasma to compare negative ion and dust effect. A few grams of micron-sized dusts are placed in the dust dispenser which is located at the upper side of the Cubical Plasma Device. The falling particles by dust dispenser are mainly charged up by the collection of the background plasma. The change in parameters due to negative ion production are characterized by measuring the floating and plasma potential, electron temperature and negative ion density using electric probes.

  12. Electric field strength and plasma delay in silicon surface barrier detector

    International Nuclear Information System (INIS)

    Kanno, I.; Inbe, T.; Kanazawa, S.; Kimura, I.

    1994-01-01

    The resistivity change of a silicon irradiated by high energy neutrons became an interest of study associated with the large scale accelerator projects . The increase of the resistivity of the silicon of a silicon surface barrier detector (SSBD) was studied as a function of neutron fluence. The plasma delay, which was an interesting but not favorite timing property of the SSBD, was reported being dependent on the resistivity of silicon . The neutron irradiation brings the change of timing property as well as the resistivity change on the SSBD. The resistivity dependence of the plasma delay should be studied for the purpose of high energy accelerator experiments. Some empirical formulae of the plasma delay were reported, however, there were no discussions on the physical meanings of the resistivity dependence of the plasma delay. The plasma delay in a SSBD is discussed in the light of electric field strength in the depletion layer of the SSBD. The explanation of the plasma delay is presented taking into account of the competing two electric forces. The resistivity of the silicon affects the plasma delay through the electric forces. 3 figs, 3 refs. (author)

  13. Microscopic electrical conductivity of nanodiamonds after thermal and plasma treatments

    Czech Academy of Sciences Publication Activity Database

    Čermák, Jan; Kozak, Halyna; Stehlík, Štěpán; Švrček, V.; Pichot, V.; Spitzer, D.; Kromka, Alexander; Rezek, Bohuslav

    2016-01-01

    Roč. 1, č. 16 (2016), s. 1105-1111 ISSN 2059-8521 R&D Projects: GA ČR GA15-01809S Institutional support: RVO:68378271 Keywords : atomic force microscopy * conductive AFM * diamond * nanoparticles * plasma Subject RIV: BM - Solid Matter Physics ; Magnetism

  14. Relativistic Scott correction in self-generated magnetic fields

    DEFF Research Database (Denmark)

    Erdos, Laszlo; Fournais, Søren; Solovej, Jan Philip

    2012-01-01

    /3}$ and it is unchanged by including the self-generated magnetic field. We prove the first correction term to this energy, the so-called Scott correction of the form $S(\\alpha Z) Z^2$. The current paper extends the result of \\cite{SSS} on the Scott correction for relativistic molecules to include a self......-generated magnetic field. Furthermore, we show that the corresponding Scott correction function $S$, first identified in \\cite{SSS}, is unchanged by including a magnetic field. We also prove new Lieb-Thirring inequalities for the relativistic kinetic energy with magnetic fields....

  15. Dynamic characteristics of non-ideal plasmas in an external high frequency electric field

    Energy Technology Data Exchange (ETDEWEB)

    Adamyan, V M [Department of Theoretical Physics, I. I. Mechnikov Odessa National University, 65026 Odessa (Ukraine); Djuric, Z [Silvaco Data System, Silvaco Technology Centre, Compass Point, St. Ives PE27 5JL (United Kingdom); Mihajlov, A A [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Sakan, N M [Institute of Physics, PO Box 57, 11001 Belgrade (Serbia and Montenegro); Tkachenko, I M [Department of Applied Mathematics, ETSII, Polytechnic University of Valencia, Camino de Vera s/n, Valencia 46022 (Spain)

    2004-07-21

    The dynamic electric conductivity, dielectric permeability and refraction and reflection coefficients of a completely ionized gaseous plasma in a high frequency (HF) external electric field are calculated. These results are obtained within the self-consistent field approach developed earlier for the static conductivity determination. The plasma electron density, N{sub e}, and temperature, T, varied within the following limits: 10{sup 19} {<=} N{sub e} {<=} 10{sup 21} cm{sup -3} and 2 x 10{sup 4} {<=} T {<=} 10{sup 6} K, respectively. The external electric field frequency, f, varied in the range 3 GHz{<=} f {<=} 0.05{omicron}{sub p}, where {omicron}{sub p} is the circular plasma frequency. Thus, the upper limit for f is either in the microwave or in the far infrared frequency band. The final results are shown in a parameterized form, suitable for laboratory applications.

  16. Dynamic characteristics of non-ideal plasmas in an external high frequency electric field

    International Nuclear Information System (INIS)

    Adamyan, V M; Djuric, Z; Mihajlov, A A; Sakan, N M; Tkachenko, I M

    2004-01-01

    The dynamic electric conductivity, dielectric permeability and refraction and reflection coefficients of a completely ionized gaseous plasma in a high frequency (HF) external electric field are calculated. These results are obtained within the self-consistent field approach developed earlier for the static conductivity determination. The plasma electron density, N e , and temperature, T, varied within the following limits: 10 19 ≤ N e ≤ 10 21 cm -3 and 2 x 10 4 ≤ T ≤ 10 6 K, respectively. The external electric field frequency, f, varied in the range 3 GHz≤ f ≤ 0.05ο p , where ο p is the circular plasma frequency. Thus, the upper limit for f is either in the microwave or in the far infrared frequency band. The final results are shown in a parameterized form, suitable for laboratory applications

  17. A Model for Periodic Nonlinear Electric Field Structures in Space Plasmas

    International Nuclear Information System (INIS)

    Qureshi, M.N.S.; Shi Jiankui; Liu Zhenxing

    2009-01-01

    In this study, we present a physical model to explain the generation mechanism of nonlinear periodic waves with a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field. The 'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when the Mach number, direction of propagation, and the initial electric field satisfy certain plasma conditions. For the parallel propagation, the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electric field and Mach number but its frequency decreases with the increase of Mach number. The amplitude and frequency of the electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky, and its amplitude increases with the increase of initial electric field. For the oblique propagation, only periodic electric field wave with an ion-cyclotron mode obtained, its amplitude and frequency increase with the increase of Mach number and become spiky. From our model the electric field structures show periodic, spiky, and saw-tooth behaviours corresponding to different plasma conditions.

  18. A study on the effect of heat treatment on electrical properties of plasma sprayed YSZ

    International Nuclear Information System (INIS)

    Elshikh, S.S.M.

    2012-01-01

    Free standing samples of plasma sprayed (PS) zirconia partially stabilized with yettria (YSZ) were prepared with two machines of plasma spray deposition (Triplex gun- 100 kw, F-4 gun 64 kw) have different electrical power and spraying parameters, which produced different microstructures; contain different amounts and varieties of pores and micro-cracks.The study included heat treatment of samples at 1200 degree C for 1 h, 5 h, 10 h, 100 h and 500 h, to study the changes in macrostructure (pores and micro-cracks) which affect the electrical conductivity.The electrical properties (resistively, electrical conductivity) of plasma sprayed ZrO 2 stabilized by 8 wt. % Y 2 O 3 samples were determined by using electrical impedance spectroscopy (IS). Specimen's microstructure was examined by optical microscopy. By measuring electrical properties and connected porosity percent of the coatings obtained under various spraying conditions, it would be possible to select the optimum spraying condition to spray coatings which have high efficiency at high temperature.The results showed that the electrical conductivity of (YSZ) samples after heat treatment increased by a rate of (20%-30%) as compared to that of as sprayed.

  19. Electrical conductivity of highly ionized dense hydrogen plasma

    International Nuclear Information System (INIS)

    Radtke, R.; Guenther, K.

    1976-01-01

    A diagnostic technique for the determination of pressure, temperature and its radial distribution, the strength of the electric field and the current of a wall-stabilized pulse hydrogen arc at a pressure of 10 atm and a maximum power of 120 kW/cm arc length is developed. (author)

  20. Analysis of influence of the radial electric field on turbulent transport in tandem mirror plasma

    International Nuclear Information System (INIS)

    Khvesyuk, Vladimir I.; Chirkov, Alexei Yu.; Pshenichnikov, Anton A.

    2000-01-01

    The model of anomalous transport in cylindrical non-uniform steady state plasma in uniform magnetic field under the influence of many mode drift wave oscillations is suggested. The effect of anomalous transport suppression due to radial electric field is studied, and physical picture of H mode in plasma of GAMMA-10 tandem mirror device is considered. Presented theoretical and numerical results agree with the experimental data obtained on GAMMA-10. (author)

  1. Research on electric and thermal characteristics of plasma torch based on similarity theory

    International Nuclear Information System (INIS)

    Cheng Changming; Tang Deli; Lan Wei

    2007-01-01

    Configuration and working principle of a DC non-transferred plasma torch have been introduced. Based on similarity theory, connections between the electric-thermal characteristics and operational parameter such as flowing gas rate and arc power have been investigated. Calculation and experiment are compared. The results indicate that the calculation results are in agreement with experimental ones. The formulas can be used for plasma torch improvement and optimization. (authors)

  2. Characteristic study of DC electric Arc plasma igniter jet

    International Nuclear Information System (INIS)

    Lan Yudan; He Liming; Du Hongliang; Wang Feng; Chen Xin

    2012-01-01

    The spectrometer was adopted to measure the emission spectrum of Ar plasma jet at the igniter exit. Boltzmann curve slope method was applied to calculate the jet electron temperature. Ionization equilibrium equation was used to calculate jet temperature and measure the laws that jet length, jet velocity, electron temperature and jet temperature of igniter exit change with arc current and inlet Ar flow rate. Whether the electron temperature could be used to replace jet temperature in aircraft plasma arc jet was also discussed. The experiment results show that arc current reduces with the rising of inlet Ar flow rate; exit jet length and velocity increase with the rising of arc current, and increase at first and then reduce with the rising of inlet Ar flow rate; exit electron temperature, electron density and jet temperature increase with the rising of arc current and reduce with the rising of inlet Ar flow rate. (authors)

  3. Effect of Electric Discharge on Properties of Nano-Particulate Catalyst for Plasma-Catalysis.

    Science.gov (United States)

    Lee, Chung Jun; Kim, Jip; Kim, Taegyu

    2016-02-01

    Heterogeneous catalytic processes have been used to produce hydrogen from hydrocarbons. However, high reforming temperature caused serious catalyst deteriorations and low energy efficiency. Recently, a plasma-catalyst hybrid process was used to reduce the reforming temperature and to improve the stability and durability of reforming catalysts. Effect of electric discharges on properties of nanoparticulate catalysts for plasma-catalysis was investigated in the present study. Catalyst-bed porosity was varied by packing catalyst beads with the different size in a reactor. Discharge power and onset voltage of the plasma were measured as the catalyst-bed porosity was varied. The effect of discharge voltage, frequency and voltage waveforms such as the sine, pulse and square was investigated. We found that the optimal porosity of the catalyst-bed exists to maximize the electric discharge. At a low porosity, the electric discharge was unstable to be sustained because the space between catalysts got narrow nearly close to the sheath region. On the other hand, at a high porosity, the electric discharge became weak because the plasma was not sufficient to interact with the surface of catalysts. The discharge power increased as the discharge voltage and frequency increased. The square waveform was more efficient than the sine and pulse one. At a high porosity, however, the effect of the voltage waveform was not considerable because the space between catalysts was too large for plasma to interact with the surface of catalysts.

  4. Dusty plasmas in a constant electric field: Role of the electron drag force

    International Nuclear Information System (INIS)

    Khrapak, S.A.; Morfill, G.E.

    2004-01-01

    We investigate the forces experienced by a microparticle immersed in a weakly ionized plasma with constant electric field. These are electric force and the forces associated with the momentum transfer from electrons and ions drifting in the field (electron and ion drag forces). It is shown that the effect of the electron drag, which is often neglected, can be substantial in a certain parameter range. Numerical calculation of the forces for a reasonable set of plasma parameters is performed to illustrate the importance of this effect

  5. Phase diagram of structure of radial electric field in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2002-01-01

    A set of transport equations in toroidal helical plasmas is analyzed, including the bifurcation of the radial electric field. Multiple solutions of E r for the ambipolar condition induces domains of different electric polarities. A structure of the domain interface is analyzed and a phase diagram is obtained in the space of the external control parameters. The region of the reduction of the anomalous transport is identified. (author)

  6. Plasma waves and electrical discharges stimulated by beam operations on a high altitude satellite

    International Nuclear Information System (INIS)

    Koons, H.C.; Cohen, H.A.

    1982-01-01

    A satellite experiment was conducted to measure the characteristics of the spacecraft charging process near synchronous orbit. The payload included a particle beam system (both an electron gun and an ion gun) and a charging electrical effects analyzer consisting of a pulse shape analyzer, a VLF analyzer, and an RF analyzer. The characteristics of plasma waves and electrical discharges measured by these instruments during electron and ion beam operations are discussed

  7. Observation of interference between stark and electric quadrupole transitions in LIF from He atoms in plasmas

    International Nuclear Information System (INIS)

    Takiyama, K.; Namba, S.; Furukawa, S.; Oda, T.; James, B.W.; Andruczyk, D.

    2004-01-01

    Interference between Stark-induced dipole and electric quadrupole amplitudes was observed in a He hollow cathode plasma with axial magnetic field perpendicular to the sheath electric field E by laser-induced fluorescence (LIF) method. Circularly polarized LIF signals were observed in the sheath region. Spatial profile of the degree of polarization P c showed characteristic features of the interference. Using theoretically calculated P c -E relationship, E-profile was successfully obtained form the measure P c . (author)

  8. The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array

    International Nuclear Information System (INIS)

    Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2012-01-01

    Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

  9. 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)

  10. Growth of carbon nanotubes in arc plasma treated graphite disc: microstructural characterization and electrical conductivity study

    Science.gov (United States)

    Nayak, B. B.; Sahu, R. K.; Dash, T.; Pradhan, S.

    2018-03-01

    Circular graphite discs were treated in arc plasma by varying arcing time. Analysis of the plasma treated discs by field emission scanning electron microscope revealed globular grain morphologies on the surfaces, but when the same were observed at higher magnification and higher resolution under transmission electron microscope, growth of multiwall carbon nanotubes of around 2 nm diameter was clearly seen. In situ growth of carbon nanotube bundles/bunches consisting of around 0.7 nm tube diameter was marked in the case of 6 min treated disc surface. Both the untreated and the plasma treated graphite discs were characterized by X-ray diffraction, energy dispersive spectra of X-ray, X-ray photoelectron spectroscopy, transmission electron microscopy, micro Raman spectroscopy and BET surface area measurement. From Raman spectra, BET surface area and microstructure observed in transmission electron microscope, growth of several layers of graphene was identified. Four-point probe measurements for electrical resistivity/conductivity of the graphite discs treated under different plasma conditions showed significant increase in conductivity values over that of untreated graphite conductivity value and the best result, i.e., around eightfold increase in conductivity, was observed in the case of 6 min plasma treated sample exhibiting carbon nanotube bundles/bunches grown on disc surface. By comparing the microstructures of the untreated and plasma treated graphite discs, the electrical conductivity increase in graphite disc is attributed to carbon nanotubes (including bundles/bunches) growth on disc surface by plasma treatment.

  11. Measurement of electric field and gradient in the plasma sheath using clusters of floating microspheres

    International Nuclear Information System (INIS)

    Sheridan, T. E.; Katschke, M. R.; Wells, K. D.

    2007-01-01

    A method for measuring the time-averaged vertical electric field and its gradient in the plasma sheath using clusters with n=2 or 3 floating microspheres of known mass is described. The particle charge q is found by determining the ratio of the breathing frequency to the center-of-mass frequency for horizontal (in-plane) oscillations. The electric field at the position of the particles is then calculated using the measured charge-to-mass ratio, and the electric-field gradient is determined from the vertical resonance frequency. The Debye length is also found. Experimental results are in agreement with a simple sheath model

  12. Transport modelling including radial electric field and plasma rotation

    International Nuclear Information System (INIS)

    Fukuyama, A.; Fuji, Y.; Itoh, S.-I.

    1994-01-01

    Using a simple turbulent transport model with a constant diffusion coefficient and a fixed temperature profile, the density profile in a steady state and the transient behaviour during the co and counter neutral beam injection are studied. More consistent analysis has been initiated with a turbulent transport model based on the current diffusive high-n ballooning mode. The enhancement of the radial electric field due to ion orbit losses and the reduction of the transport due to the poloidal rotation shear are demonstrated. The preliminary calculation indicates a sensitive temperature dependence of the density profile. (author)

  13. Transport analysis of radial electric field in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2004-01-01

    A set of transport equations is analyzed which induces the radial transition of the electric field. A temperature profile which is related with the transport barrier is obtained by use of the theoretical model for the anomalous transport diffusivities. A dependence on the different initial condition is found even if the same values of the control parameters are used in calculations. A study of the temporal evolution of E r is done. We examine the test of the adopted theoretical model for the anomalous transport diffusivities compared with the experimental result in Large Helical Device (LHD). (authors)

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

    International Nuclear Information System (INIS)

    Kanno, Ikuo

    1994-01-01

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

  15. Magnetic and electric deflector spectrometers for ion emission analysis from laser generated plasma

    Directory of Open Access Journals (Sweden)

    Torrisi Lorenzo

    2018-01-01

    Full Text Available The pulsed laser-generated plasma in vacuum and at low and high intensities can be characterized using different physical diagnostics. The charge particles emission can be characterized using magnetic, electric and magnet-electrical spectrometers. Such on-line techniques are often based on time-of-flight (TOF measurements. A 90° electric deflection system is employed as ion energy analyzer (IEA acting as a filter of the mass-to-charge ratio of emitted ions towards a secondary electron multiplier. It determines the ion energy and charge state distributions. The measure of the ion and electron currents as a function of the mass-to-charge ratio can be also determined by a magnetic deflector spectrometer, using a magnetic field of the order of 0.35 T, orthogonal to the ion incident direction, and an array of little ion collectors (IC at different angles. A Thomson parabola spectrometer, employing gaf-chromix as detector, permits to be employed for ion mass, energy and charge state recognition. Mass quadrupole spectrometry, based on radiofrequency electric field oscillations, can be employed to characterize the plasma ion emission. Measurements performed on plasma produced by different lasers, irradiation conditions and targets are presented and discussed. Complementary measurements, based on mass and optical spectroscopy, semiconductor detectors, fast CCD camera and Langmuir probes are also employed for the full plasma characterization. Simulation programs, such as SRIM, SREM, and COMSOL are employed for the charge particle recognition.

  16. Effect of electric charge on the transperitoneal transport of plasma proteins during CAPD

    NARCIS (Netherlands)

    Buis, B.; Koomen, G. C.; Imholz, A. L.; Struijk, D. G.; Reddingius, R. E.; Arisz, L.; Krediet, R. T.

    1996-01-01

    BACKGROUND: Controversy exists as to whether electric charges of plasma proteins influence their transport across the peritoneal membrane during CAPD. Fixed negative charges in the peritoneal membrane are diminished during peritonitis in rats. METHODS: Peritoneal clearances of 10 proteins and their

  17. Diagnostics of electric fields in plasmas using Stark spectroscopy of xenon atoms

    NARCIS (Netherlands)

    Bowden, M.D.; Jiang, Tao; Visser, B.; Kroesen, G.M.W.

    2003-01-01

    Plasma breakdown is the process that occurs when a voltage is applied across an electrode gap and the neutral gas in the gap becomes ionized and electrically conducting. The goal of our research is to study breakdown processes experimentally on a sub-nanosecond timescale, so that features of

  18. Magnetic and electric deflector spectrometers for ion emission analysis from laser generated plasma

    Science.gov (United States)

    Torrisi, Lorenzo; Costa, Giuseppe; Ceccio, Giovanni; Cannavò, Antonino; Restuccia, Nancy; Cutroneo, Mariapompea

    2018-01-01

    The pulsed laser-generated plasma in vacuum and at low and high intensities can be characterized using different physical diagnostics. The charge particles emission can be characterized using magnetic, electric and magnet-electrical spectrometers. Such on-line techniques are often based on time-of-flight (TOF) measurements. A 90° electric deflection system is employed as ion energy analyzer (IEA) acting as a filter of the mass-to-charge ratio of emitted ions towards a secondary electron multiplier. It determines the ion energy and charge state distributions. The measure of the ion and electron currents as a function of the mass-to-charge ratio can be also determined by a magnetic deflector spectrometer, using a magnetic field of the order of 0.35 T, orthogonal to the ion incident direction, and an array of little ion collectors (IC) at different angles. A Thomson parabola spectrometer, employing gaf-chromix as detector, permits to be employed for ion mass, energy and charge state recognition. Mass quadrupole spectrometry, based on radiofrequency electric field oscillations, can be employed to characterize the plasma ion emission. Measurements performed on plasma produced by different lasers, irradiation conditions and targets are presented and discussed. Complementary measurements, based on mass and optical spectroscopy, semiconductor detectors, fast CCD camera and Langmuir probes are also employed for the full plasma characterization. Simulation programs, such as SRIM, SREM, and COMSOL are employed for the charge particle recognition.

  19. The effect of an alternating electric field on a totally ionised plasma

    International Nuclear Information System (INIS)

    Baglin, H.; Brin, A.; Ozias, Y.; Salmon, J.

    1960-01-01

    The equation giving the distribution function of the electrons in a steady-state, for a fully ionized plasma in an a.c. field, are provided from the Fokker-Planck equation. The electric conductivity is complex and depends on the frequency. (author) [fr

  20. Incoherent-scatter radar measurements of electric field and plasma in the auroral ionosphere

    International Nuclear Information System (INIS)

    Vondrak, R.

    1983-01-01

    This chapter summarizes Chatanika radar measurements of electric fields and currents, and their relation to E-region ionization and conductivity. Electric-field coupling between the ionosphere and magnetosphere and the relationship between field-aligned currents and meridional ionospheric currents are examined. Topics considered include the diurnal pattern of the ionization and electric field; electrical coupling between the ionosphere and magnetosphere; and the relationship between meridional currents and field-aligned currents. It is concluded that the incoherent-scatter radar technique has been developed into a powerful method for remotely measuring the electrical and thermal properties of the auroral ionospheric plasma, and that the usefulness of the radar measurements is greatly enhanced when combined with simultaneous satellite measurements

  1. Experimental observation of the inductive electric field and related plasma nonuniformity in high frequency capacitive discharge

    International Nuclear Information System (INIS)

    Ahn, S. K.; Chang, H. Y.

    2008-01-01

    To elucidate plasma nonuniformity in high frequency capacitive discharges, Langmuir probe and B-dot probe measurements were carried out in the radial direction in a cylindrical capacitive discharge driven at 90 MHz with argon pressures of 50 and 400 mTorr. Through the measurements, a significant inductive electric field (i.e., time-varying magnetic field) was observed at the radial edge, and it was found that the inductive electric field creates strong plasma nonuniformity at high pressure operation. The plasma nonuniformity at high pressure operation is physically similar to the E-H mode transition typically observed in inductive discharges. This result agrees well with the theories of electromagnetic effects in large area and/or high frequency capacitive discharges

  2. Plasma Polypyrrole Coated Hybrid Composites with Improved Mechanical and Electrical Properties for Aerospace Applications

    Science.gov (United States)

    Yavuz, Hande; Bai, Jinbo

    2018-06-01

    This paper deals with the dielectric barrier discharge assisted continuous plasma polypyrrole deposition on CNT-grafted carbon fibers for conductive composite applications. The simultaneous effects of three controllable factors have been studied on the electrical resistivity (ER) of these two material systems based on multivariate experimental design methodology. A posterior probability referring to Benjamini-Hochberg (BH) false discovery rate was explored as multiple testing corrections of the t-test p values. BH significance threshold of 0.05 was produced truly statistically significant coefficients to describe ER of two material systems. A group of plasma modified samples was chosen to be used for composite manufacturing to drive an assessment of interlaminar shear properties under static loading. Transversal and longitudinal electrical resistivity (DC, ω =0) of composite samples were studied to compare both the effects of CNT grafting and plasma modification on ER of resultant composites.

  3. Interaction of plasma cloud with external electric field in lower ionosphere

    Directory of Open Access Journals (Sweden)

    Y. S. Dimant

    2010-03-01

    Full Text Available In the auroral lower-E and upper-D region of the ionosphere, plasma clouds, such as sporadic-E layers and meteor plasma trails, occur daily. Large-scale electric fields, created by the magnetospheric dynamo, will polarize these highly conducting clouds, redistributing the electrostatic potential and generating anisotropic currents both within and around the cloud. Using a simplified model of the cloud and the background ionosphere, we develop the first self-consistent three-dimensional analytical theory of these phenomena. For dense clouds, this theory predicts highly amplified electric fields around the cloud, along with strong currents collected from the ionosphere and circulated through the cloud. This has implications for the generation of plasma instabilities, electron heating, and global MHD modeling of magnetosphere-ionosphere coupling via modifications of conductances induced by sporadic-E clouds.

  4. Measurements of plasma density fluctuations and electric wave fields using spherical electrostatic probes

    International Nuclear Information System (INIS)

    Eriksson, A.I.; Bostroem, R.

    1995-04-01

    Spherical electrostatic probes are in wide use for the measurements of electric fields and plasma density. This report concentrates on the measurements of fluctuations of these quantities rather than background values. Potential problems with the technique include the influence of density fluctuations on electric field measurements and vice versa, effects of varying satellite potential, and non-linear rectification in the probe and satellite sheaths. To study the actual importance of these and other possible effects, we simulate the response of the probe-satellite system to various wave phenomena in the plasma by applying approximate analytical as well as numerical methods. We use a set of non-linear probe equations, based on probe characteristics experimentally obtained in space, and therefore essentially independent of any specific probe theory. This approach is very useful since the probe theory for magnetized plasmas is incomplete. 47 refs

  5. Plasma Polypyrrole Coated Hybrid Composites with Improved Mechanical and Electrical Properties for Aerospace Applications

    Science.gov (United States)

    Yavuz, Hande; Bai, Jinbo

    2017-09-01

    This paper deals with the dielectric barrier discharge assisted continuous plasma polypyrrole deposition on CNT-grafted carbon fibers for conductive composite applications. The simultaneous effects of three controllable factors have been studied on the electrical resistivity (ER) of these two material systems based on multivariate experimental design methodology. A posterior probability referring to Benjamini-Hochberg (BH) false discovery rate was explored as multiple testing corrections of the t-test p values. BH significance threshold of 0.05 was produced truly statistically significant coefficients to describe ER of two material systems. A group of plasma modified samples was chosen to be used for composite manufacturing to drive an assessment of interlaminar shear properties under static loading. Transversal and longitudinal electrical resistivity (DC, ω =0) of composite samples were studied to compare both the effects of CNT grafting and plasma modification on ER of resultant composites.

  6. Core radial electric field and transport in Wendelstein 7-X plasmas

    Science.gov (United States)

    Pablant, N. A.; Langenberg, A.; Alonso, A.; Beidler, C. D.; Bitter, M.; Bozhenkov, S.; Burhenn, R.; Beurskens, M.; Delgado-Aparicio, L.; Dinklage, A.; Fuchert, G.; Gates, D.; Geiger, J.; Hill, K. W.; Höfel, U.; Hirsch, M.; Knauer, J.; Krämer-Flecken, A.; Landreman, M.; Lazerson, S.; Maaßberg, H.; Marchuk, O.; Massidda, S.; Neilson, G. H.; Pasch, E.; Satake, S.; Svennson, J.; Traverso, P.; Turkin, Y.; Valson, P.; Velasco, J. L.; Weir, G.; Windisch, T.; Wolf, R. C.; Yokoyama, M.; Zhang, D.; W7-X Team

    2018-02-01

    The results from the investigation of neoclassical core transport and the role of the radial electric field profile (Er) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the Er profile are expected to have a strong effect on both the particle and heat fluxes. Investigation of the radial electric field is important in understanding neoclassical transport and in validation of neoclassical calculations. The radial electric field is closely related to the perpendicular plasma flow (u⊥) through the force balance equation. This allows the radial electric field to be inferred from measurements of the perpendicular flow velocity, which can be measured using the x-ray imaging crystal spectrometer and correlation reflectometry diagnostics. Large changes in the perpendicular rotation, on the order of Δu⊥˜ 5 km/s (ΔEr ˜ 12 kV/m), have been observed within a set of experiments where the heating power was stepped down from 2 MW to 0.6 MW. These experiments are examined in detail to explore the relationship between heating power temperature, and density profiles and the radial electric field. Finally, the inferred Er profiles are compared to initial neoclassical calculations based on measured plasma profiles. The results from several neoclassical codes, sfincs, fortec-3d, and dkes, are compared both with each other and the measurements. These comparisons show good agreement, giving confidence in the applicability of the neoclassical calculations to the W7-X configuration.

  7. Electrical and spectroscopic diagnostic of an atmospheric double arc argon plasma jet

    International Nuclear Information System (INIS)

    Tu, X; Cheron, B G; Yan, J H; Cen, K F

    2007-01-01

    An atmospheric argon plasma jet generated by an original dc double anode plasma torch has been investigated through its electrical and spectroscopic diagnostics. The arc instabilities and dynamic behavior of the argon plasma are analyzed using classical tools such as the statistical method, fast Fourier transform (FFT) and correlation function. The takeover mode is identified as the fluctuation characteristic of the double arc argon plasma jet in our experiment. The FFT and correlation analysis of electrical signals exhibit the only characteristic frequency of 150 Hz, which originates from the torch power and is independent of any change in the operating parameters. No high frequency fluctuations (1-15 kHz) are observed. This indicates that the nature of fluctuations in an argon plasma jet is induced mainly by the undulation of the tri-phase rectified power supply. It is found that each arc root attachment is diffused rather than located at a fixed position on the anode wall. Moreover, the emission spectroscopic technique is performed to determine the electron temperature and number density of the plasma jet inside and outside the arc chamber. Along the torch axis, the measured electron temperature and number density of the double arc argon plasma drop from 12 300 K and 7.6 x 10 22 m -3 at the divergent part of the first anode nozzle, to 10 500 K and 3.1 x 10 22 m -3 at the torch exit. In addition, the validity criteria of the local thermodynamic equilibrium (LTE) state in the plasma arc are examined. The results show that the measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the double arc argon plasma at atmospheric pressure is close to the LTE state under our experimental conditions

  8. Simulation of electrical discharge in a 3.6 Joule miniature plasma focus device using SIMULINK

    International Nuclear Information System (INIS)

    Jafari, H.; Habibi, M.

    2014-01-01

    A novel technique has been developed and studied in this paper to simulate the electrical discharge circuit of a 3.6 J miniature plasma focus device (PFD) and investigate the effect of inductance variation on voltage spike and current dip. The technique is based on a correlation between the electrical discharge circuit and plasma dynamics in a very small PFD that operates at the energy of 3.6 J. The simulation inputs include the charging voltage, capacitor bank capacitance, current limiter resistance, bypass resistance as well as the time-dependent inductance and resistance of the plasma sheath which are calculated by assuming the plasma dynamics as transit times in going from one phase to the next. The variations of the most important elements in the circuit (i.e. the constant and breakdown inductances) and their effects on the current dip are studied in PFDs with low and high constant inductance. The model demonstrated for achieving a good pinch in the PFD, although the total inductance of the system should be low; however there is always an optimum inductance which causes an appropriate pinch. Furthermore, the electrical power produced by the pulsed power supply, the mechanical energy as well as the magnetic energy which are transferred into the plasma tube were obtained from simulation. The graph of electrical power demonstrated a high instantaneous increment in the power transferred into the plasma as one of the greatest advantages of the pulsed power supply. The simulation was performed using software tools within the MATLAB/SIMULINK simulation environment. The PFD, generating neutrons in the range of 10 6 to 10 10 neutrons per pulse will have substantial use in the physics and engineering applications. (authors)

  9. Separation method in the problem of a beam-plasma interaction in bounded warm plasma under the effect of HF electric field

    International Nuclear Information System (INIS)

    EI-Shorbagy, Kh.H.

    2002-11-01

    The stabilization effect of a strong HP electric field on beam-plasma instability in a cylindrical warm plasma waveguide is discussed. A new mathematical technique 'separation method' which has been applied to the two-fluid plasma model to separate the equations, which describe the system, into two parts, temporal and space parts. Plasma electrons are considered to have a thermal velocity. It is shown that a HF electric field has no essential influence on dispersion characteristics of unstable surface waves excited in a warm plasma waveguide by a low-density electron beam. The region of instability only slightly narrowing and the growth rate decreases by a small parameter and this result has been reduced compared to cold plasma. Also, it is found that the plasma electrons have not affected the solution of the space part of the problem. (author)

  10. Voltage tensor for a plasma in high frequency electromagnetic and constant electric fields in the presence of collisions

    International Nuclear Information System (INIS)

    Vigdorchik, N.E.

    1978-01-01

    The voltage tensor expression is obtained for plasma placed in a HF electromagnetic and constant electric fields. The kinetic equations with allowance for collisions are initial. Weakly ionized and completely ionized plasmas are considered. The voltage tensor for completely ionized plasma differs essentially from that for transparent media

  11. Self-generated strategic behavior in an ecological shopping task.

    Science.gov (United States)

    Bottari, Carolina; Wai Shun, Priscilla Lam; Dorze, Guylaine Le; Gosselin, Nadia; Dawson, Deirdre

    2014-01-01

    OBJECTIVES. The use of cognitive strategies optimizes performance in complex everyday tasks such as shopping. This exploratory study examined the cognitive strategies people with traumatic brain injury (TBI) effectively use in an unstructured, real-world situation. METHOD. A behavioral analysis of the self-generated strategic behaviors of 5 people with severe TBI using videotaped sessions of an ecological shopping task (Instrumental Activities of Daily Living Profile) was performed. RESULTS. All participants used some form of cognitive strategy in an unstructured real-world shopping task, although the number, type, and degree of effectiveness of the strategies in leading to goal attainment varied. The most independent person used the largest number and a broader repertoire of self-generated strategies. CONCLUSION. These results provide initial evidence that occupational therapists should examine the use of self-generated cognitive strategies in real-world contexts as a potential means of guiding therapy aimed at improving independence in everyday activities for people with TBI. Copyright © 2014 by the American Occupational Therapy Association, Inc.

  12. Direct measurement of macroscopic electric fields produced by collective effects in electron-impact experiments

    International Nuclear Information System (INIS)

    Velotta, R.; Avaldi, L.; Camilloni, R.; Giammanco, F.; Spinelli, N.; Stefani, G.

    1996-01-01

    The macroscopic electric field resulting from the space charge produced in electron-impact experiments has been characterized by using secondary electrons of well-defined energy (e.g., Auger or autoionizing electrons) as a probe. It is shown that the measurement of the kinetic-energy shifts suffered by secondary electrons is a suitable tool for the analysis of the self-generated electric field in a low-density plasma. copyright 1996 The American Physical Society

  13. Dynamical interplay between fluctuations, electric fields and transport in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Pedrosa, M.A.; Goncalves, B.

    2003-01-01

    A view of recent experimental results and progress in the characterization of the statistical properties of electrostatic turbulence in magnetically confined devices is given. An empirical similarity in the scaling properties of the probability distribution function (PDF) of turbulent transport has been observed in the plasma edge region in fusion plasmas. The investigation of the dynamical interplay between fluctuation in gradients, turbulent transport and radial electric fields has shows that these parameters are strongly coupled both in tokamak and stellarator plasmas. The bursty behaviour of turbulent transport is linked with a departure from the most probable radial gradient. The dynamical relation between fluctuations in gradients and transport is strongly affected by the presence of sheared poloidal flows which organized themselves near marginal stability. These results emphasize the importance of the statistical description of transport processes in fusion plasmas as an alternative approach to the traditional way to characterize transport based on the computation of effective transport coefficients. (author)

  14. Evolution of the radial electric field in a JET H-mode plasma

    International Nuclear Information System (INIS)

    Andrew, Y.; Hawkes, N.C.; Biewer, T.; Crombe, K.; Keeling, D.; De la Luna, E.; Giroud, C.; Korotkov, A.; Meigs, A.; Murari, A.; Nunes, I.; Sartori, R.; Tala, T.; Andrew, Y.; Hawkes, N.C.; Keeling, D.; Giroud, C.; Korotkov, A.; Meigs, A.; Biewer, T.; Crombe, K.; De la Luna, E.; Murari, A.; Nunes, I.; Sartori, R.; Tala, T.

    2008-01-01

    Results from recent measurements of carbon impurity ion toroidal and poloidal rotation velocities, ion temperature, ion density and the resulting radial electric field (E r ) profiles are presented from an evolving Joint European Torus (JET) tokamak plasma over a range of energy and particle confinement regimes. Significant levels of edge plasma poloidal rotation velocity have been measured for the first time on JET, with maximum values of ±9 km/s. Such values of poloidal rotation provide an important contribution to the total edge plasma E r profiles. Large values of shear in the measured E r profiles are observed to arise as a consequence of the presence of the edge transport barrier (ETB) and do not appear to be necessary for their formation or destruction. These results have an important impact on potential mechanisms for transport barrier triggering and sustainment in present-day and future high-performance fusion plasmas. (authors)

  15. 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

  16. Effect of radial electric field inhomogeneity on anomalous cross field plasma flux in Heliotron/Torsatron

    International Nuclear Information System (INIS)

    Yamagishi, Tomejiro; Sanuki, Heiji.

    1996-01-01

    Anomalous cross field plasma fluxes induced by the electric field fluctuations has been evaluated in a rotating plasma with shear flow in a helical system. The anomalous ion flux is evaluated by the contribution from ion curvature drift resonance continuum in the test particle model. The radial electric field induces the Doppler frequency shift which disappears in the frequency integrated anomalous flux. The inhomogeneity of the electric field (shear flow effect), however, induces a new force term in the flux. The curvature drift resonance also induces a new force term '/ which, however, did not make large influence in the ion flux in the CHS configuration. The shear flow term in the flux combined with the electric field in neoclassical flux reduces to a first order differential equation which governs the radial profile of the electric field. Numerical results indicate that the shear flow effect is important for the anomalous cross field flux and for determination of the radial electric field particularly in the peripheral region. (author)

  17. Effect of O2 plasma immersion on electrical properties and transistor performance of indium gallium zinc oxide thin films

    International Nuclear Information System (INIS)

    Liu, P.; Chen, T.P.; Liu, Z.; Tan, C.S.; Leong, K.C.

    2013-01-01

    Evolution of electrical properties and thin-film transistor characteristics of amorphous indium gallium zinc oxide (IGZO) thin films synthesized by RF sputtering with O 2 plasma immersion has been examined. O 2 plasma immersion results in an enhancement in the Hall mobility and a decrease in the electron concentration; and the transistor performance can be greatly improved by the O 2 plasma immersion. X-ray photoelectron spectroscopy analysis indicates that the effect of O 2 plasma immersion on the electrical properties and the transistor performance can be attributed to the reduction of the oxygen-related defects in the IGZO thin films. - Highlights: • Oxygen plasma immersion effect on indium gallium zinc oxide thin film properties • Oxygen-related defect reduces in the InGaZnO thin film with oxygen plasma immersion. • Increasing oxygen plasma immersion duration on device will decrease the off current. • Oxygen plasma immersion enhances the performance of device

  18. Transport analysis of oscillatory state for plasma dynamics in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2012-11-01

    In helical plasmas, two kinds of the oscillation for the plasma quantities are experimentally observed. Firstly, the limit cycle phenomena in the temporal evolution of the electrostatic potential, namely the electric pulsation, have been observed in the core region. The temporally self-generated oscillation of the radial electric field is shown as a simulation result in the core region. The dependence of the transition point for the radial electric field on the source is examined. Secondly, the density limit oscillation in the helical device was reported. To realize the oscillation phenomena at the density limit, the temporal evolution of the density profile is newly included in a simulation when the radiative loss is calculated in the edge region. Two stationary plasma states, where the transport loss or radiative loss is dominant in the edge region, are obtained. The dynamics of the plasma quantity is found to show the transition from the transport-dominated state to the radiation-dominated state. (author)

  19. Electrical conductivity of highly ionized dense hydrogen plasma. 1. Electrical measurements and diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, R; Guenther, K [Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Elektronenphysik

    1976-05-11

    A diagnostic technique for the determination of pressure, temperature and its radial distribution, the strength of the electric field and the current of a wall-stabilized pulse hydrogen arc at a pressure of 10 atm and a maximum power of 120 kW/cm arc length is developed.

  20. Heavy ion beam probe (HIBP) diagnostics as a tool for investigations into the plasma turbulence and the local electric field of dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Krupnik, L.I.; Chmyga, A.A.; Komarov, A.D.; Kozachok, A.S.; Zhezhera, A.I. [Institute of Plasma Physics, NSC KIPT, 310108 Kharkov (Ukraine); Melnikov, A.V.; Eliseev, L.G.; Lysenko, S.E.; Mavrin, V.A.; Perfilov, S.V. [Institute of Nuclear Fusion, RRC ' Kurchatov Institute' , Moscow (Russian Federation); Hidalgo, C.; Ascasibar, E.; Estrada, T.; Liniers, M.; Ochando, M.A.; Pablos, J.L. de; Pedrosa, M.A.; Tabares, F. [Laboratorio Nacional de Fusion por Confinamiento Magnetico, Asociacion EURATOM-CIEMAT, 28040-Madrid (Spain)

    2011-07-01

    One of essential achievements of the Heavy Ion Beam Probe (HIBP) diagnostics is the possibility to use it for investigation of plasma confinement by measuring the fluctuations of electric field and plasma density; the method is based on the important role of the plasma electric fields. Both edge and core transport barriers are related to a large increase in the E*B sheared flows in a fusion device. In the TJ-II stellarator the HIBP diagnostics has recently been upgraded for two-point measurements with a good spatial (1 cm) and temporal (10 {mu}s) resolution of the plasma electric potential and density, as well as their fluctuations and poloidal component of electric field, E{sub p} equals ({phi}1 - {phi}2)/{Delta}r [V/cm]; these data give chance to extract the radial turbulent particle flux: {Gamma}(r) equals {Gamma}(Epol*Btor) equals {Gamma}(E*B). (authors)

  1. Plasma-electric field controlled growth of oriented graphene for energy storage applications

    Science.gov (United States)

    Ghosh, Subrata; Polaki, S. R.; Kamruddin, M.; Jeong, Sang Mun; (Ken Ostrikov, Kostya

    2018-04-01

    It is well known that graphene grows as flat sheets aligned with the growth substrate. Oriented graphene structures typically normal to the substrate have recently attracted major attention. Most often, the normal orientation is achieved in a plasma-assisted growth and is believed to be due to the plasma-induced in-built electric field, which is usually oriented normal to the substrate. This work focuses on the effect of an in-built electric field on the growth direction, morphology, interconnectedness, structural properties and also the supercapacitor performance of various configurations of graphene structures and reveals the unique dependence of these features on the electric field orientation. It is shown that tilting of growth substrates from parallel to the normal direction with respect to the direction of in-built plasma electric field leads to the morphological transitions from horizontal graphene layers, to oriented individual graphene sheets and then interconnected 3D networks of oriented graphene sheets. The revealed transition of the growth orientation leads to a change in structural properties, wetting nature, types of defect in graphitic structures and also affects their charge storage capacity when used as supercapacitor electrodes. This simple and versatile approach opens new opportunities for the production of potentially large batches of differently oriented and structured graphene sheets in one production run.

  2. Turbulence in tokamak plasmas. Effect of a radial electric field shear

    International Nuclear Information System (INIS)

    Payan, J.

    1994-05-01

    After a review of turbulence and transport phenomena in tokamak plasmas and the radial electric field shear effect in various tokamaks, experimental measurements obtained at Tore Supra by the means of the ALTAIR plasma diagnostic technique, are presented. Electronic drift waves destabilization mechanisms, which are the main features that could describe the experimentally observed microturbulence, are then examined. The effect of a radial electric field shear on electronic drift waves is then introduced, and results with ohmic heating are studied together with relations between turbulence and transport. The possible existence of ionic waves is rejected, and a spectral frequency modelization is presented, based on the existence of an electric field sheared radial profile. The position of the inversion point of this field is calculated for different values of the mean density and the plasma current, and the modelization is applied to the TEXT tokamak. The radial electric field at Tore Supra is then estimated. The effect of the ergodic divertor on turbulence and abnormal transport is then described and the density fluctuation radial profile in presence of the ergodic divertor is modelled. 80 figs., 120 refs

  3. Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory

    International Nuclear Information System (INIS)

    Yoon, P. H.; Schlickeiser, R.; Kolberg, U.

    2014-01-01

    Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density n e are calculated as |δB|=√((δB) 2 )=2.8(n e m e c 2 ) 1/2 g 1/2 β e 7/4 and |δE|=√((δE) 2 )=3.2(n e m e c 2 ) 1/2 g 1/3 β e 2 , where g and β e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |δB|=6·10 −18 G and |δE|=2·10 −16 G result

  4. On the Role of the Electrical Field in Spark Plasma Sintering of UO2+x

    Science.gov (United States)

    Tyrpekl, Vaclav; Naji, Mohamed; Holzhäuser, Michael; Freis, Daniel; Prieur, Damien; Martin, Philippe; Cremer, Bert; Murray-Farthing, Mairead; Cologna, Marco

    2017-01-01

    The electric field has a large effect on the stoichiometry and grain growth of UO2+x during Spark Plasma Sintering. UO2+x is gradually reduced to UO2.00 as a function of sintering temperature and time. A gradient in the oxidation state within the pellets is observed in intermediate conditions. The shape of the gradient depends unequivocally on the direction of the electrical field. The positive surface of the pellet shows a higher oxidation state compared to the negative one. An area with larger grain size is found close to the positive electrode, but not in contact with it. We interpret these findings with the redistribution of defects under an electric field, which affect the stoichiometry of UO2+x and thus the cation diffusivity. The results bear implications for understanding the electric field assisted sintering of UO2 and non-stoichiometric oxides in general. PMID:28422164

  5. Electrical method for the measurements of volume averaged electron density and effective coupled power to the plasma bulk

    Science.gov (United States)

    Henault, M.; Wattieaux, G.; Lecas, T.; Renouard, J. P.; Boufendi, L.

    2016-02-01

    Nanoparticles growing or injected in a low pressure cold plasma generated by a radiofrequency capacitively coupled capacitive discharge induce strong modifications in the electrical parameters of both plasma and discharge. In this paper, a non-intrusive method, based on the measurement of the plasma impedance, is used to determine the volume averaged electron density and effective coupled power to the plasma bulk. Good agreements are found when the results are compared to those given by other well-known and established methods.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-01-12

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

  7. Filamentation and networking of electric currents in dense Z-pinch plasmas

    International Nuclear Information System (INIS)

    Kukushkin, A.B.; Rantsev-Kartinov, V.A.

    2001-01-01

    The results of high-resolution processing using the multilevel dynamical contrasting method of earlier experiments on linear Z-pinches are presented which illustrate formation of a dynamical percolating network woven by long-living filaments of electric current. A qualitative approach is outlined which treats long-living filaments as a classical plasma formation governed by the long-range quantum bonds provided, at the microscopical level, by nanotubes of elements of optimal valence. The self-similarity of structuring in laboratory and cosmic plasmas is shown, and examples are found of nanotube-like and/or fullerene-like structures of cosmic length scales. (author)

  8. Filamentation and networking of electric currents in dense Z-pinch plasmas

    International Nuclear Information System (INIS)

    Kukushkin, A.B.; Rantsev-Kartinov, V.A.

    1999-01-01

    The results of high-resolution processing using the multilevel dynamical contrasting method of earlier experiments on linear Z-pinches are presented which illustrate formation of a dynamical percolating network woven by long-living filaments of electric current. A qualitative approach is outlined which treats long-living filaments as a classical plasma formation governed by the long-range quantum bonds provided, at the micro-scopical level, by nanotubes of elements of optimal valence. The self-similarity of structuring in laboratory and cosmic plasmas is shown, and examples are found of nanotube-like and/or fullerene-like structures of cosmic length scales. (author)

  9. Experimental investigation on electrical characteristics and dose measurement of dielectric barrier discharge plasma device used for therapeutic application.

    Science.gov (United States)

    Shahbazi Rad, Zahra; Abbasi Davani, Fereydoun

    2017-04-01

    In this research, a Dielectric Barrier Discharge (DBD) plasma device operating in air has been made. The electrical characteristics of this device like instantaneous power, dissipated power, and discharge capacitance have been measured. Also, the effects of applied voltage on the dissipated power and discharge capacitance of the device have been investigated. The determination of electrical parameters is important in DBD plasma device used in living tissue treatment for choosing the proper treatment doses and preventing the destructive effects. The non-thermal atmospheric pressure DBD plasma source was applied for studying the acceleration of blood coagulation time, in vitro and wound healing time, in vivo. The citrated blood drops coagulated within 5 s treatment time by DBD plasma. The effects of plasma temperature and electric field on blood coagulation have been studied as an affirmation of the applicability of the constructed device. Also, the effect of constructed DBD plasma on wound healing acceleration has been investigated.

  10. Rocket measurements within a polar cap arc: Plasma, particle, and electric circuit parameters

    International Nuclear Information System (INIS)

    Weber, E.J.; Ballenthin, J.O.; Basu, S.; Carlson, H.C.; Hardy, D.A.; Maynard, N.C.; Smiddy, M.; Kelley, M.C.; Fleischman, J.R.; Sheehan, R.E.; Pfaff, R.F.; Rodriguez, P.

    1989-01-01

    An instrumented rocket payload was launched into a polar cap F layer aurora to investigate the energetic particle, plasma, and electric circuit parameters of a Sun-aligned arc. On-board instruments measured energetic electron flux, ion composition and density fluctuations, electron density and temperature, electron density fluctuations, and ac and dc electric fields. Real-time all-sky imaging photometer measurements of the location and motion of the aurora, were used to determine the proper geophysical situation for launch. Comparison of the in situ measurements with remote optical measurements shows that the arc was produced by fluxes of low-energy (< 1 keV) electrons. Field-aligned potentials in the arc inferred from the electron spectra had a maximum value of approximately 300 V, and from the spectral shape a parent population of preaccelerated electrons characteristic of the boundary plasma sheet or magnetosheath was inferred. Electric field components along and across the arc show sunward flow within the arc and duskward drift of the arc consistent with the drift direction and speed determined from optical imaging. Thus this arc is drifting duskward under the influence of the convection electric field. Three possible explanations for this (field-aligned currents, chemistry, and transport) are considered. Finally, ionospheric irregularity and electric field fluctuations indicate two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability

  11. Plasma barodiffusion in inertial-confinement-fusion implosions: application to observed yield anomalies in thermonuclear fuel mixtures.

    Science.gov (United States)

    Amendt, Peter; Landen, O L; Robey, H F; Li, C K; Petrasso, R D

    2010-09-10

    The observation of large, self-generated electric fields (≥10(9)  V/m) in imploding capsules using proton radiography has been reported [C. K. Li, Phys. Rev. Lett. 100, 225001 (2008)]. A model of pressure gradient-driven diffusion in a plasma with self-generated electric fields is developed and applied to reported neutron yield deficits for equimolar D3He [J. R. Rygg, Phys. Plasmas 13, 052702 (2006)] and (DT)3He [H. W. Herrmann, Phys. Plasmas 16, 056312 (2009)] fuel mixtures and Ar-doped deuterium fuels [J. D. Lindl, Phys. Plasmas 11, 339 (2004)]. The observed anomalies are explained as a mild loss of deuterium nuclei near capsule center arising from shock-driven diffusion in the high-field limit.

  12. Effect of rotating electric field on 3D complex (dusty) plasma

    Science.gov (United States)

    Wörner, L.; Nosenko, V.; Ivlev, A. V.; Zhdanov, S. K.; Thomas, H. M.; Morfill, G. E.; Kroll, M.; Schablinski, J.; Block, D.

    2011-06-01

    The effect of rotating electric field on 3D particle clusters suspended in rf plasma was studied experimentally. Spheroidal clusters were suspended inside a glass box mounted on the lower horizontal rf electrode, with gravity partially balanced by thermophoretic force. Clusters rotated in the horizontal plane, in response to rotating electric field that was created inside the box using conducting coating on its inner surfaces ("rotating wall" technique). Cluster rotation was always in the direction of applied field and had a shear in the vertical direction. The angular speed of rotation was 104-107 times lower than applied frequency. The experiment is compared to a recent theory.

  13. An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

    Science.gov (United States)

    De, B. R.; Srnka, L. J.

    1978-01-01

    Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

  14. Nonequilibrium Thermodynamic Treatment of a Warm Plasma in Strong Magnetic and Electric Fields

    International Nuclear Information System (INIS)

    Abourabia, A.M.; Shahein, R.A.

    2008-01-01

    In the framework of the irreversible thermodynamics we study a rarefied and collisional warm electron plasma under the effects of external strong magnetic and electric fields which generate small wave amplitudes. We adopt the linear theory and normal mode solution in the MHD model to calculate the perturbations in pressure, mass density, components of velocity, electric and magnetic fields. By applying the second law of thermodynamics it is concluded that the change in the internal energy of the plasma particles predicts whether they gain from or lose energy to the generated waves .The obtained results agree with the physical ground bounded by the positive nature of the entropy production. The predictions have been carried out within the range of the frequency of the generated waves and the distance from the Debye sphere

  15. Electrical conductivity of highly ionized dense hydrogen plasma. II. Comparison of experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, K [Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Elektronenphysik; Popovic, M M; Popovic, S S; Radtke, R

    1976-05-11

    The electrical conductivity of a non-ideal hydrogen plasma at p = 10 atm and T = 14,000-21,500 K is derived from electrical measurements and the radial temperature distribution of a pulsed wall-stabilized hydrogen arc using the theoretical temperature dependence of conductivity in an ideal binary collision plasma. From the comparison of theory and experiment, a suggestion to modify the cut-off parameter for charged particle potential from rsub(D) is derived, where rsub(D) is the Debye length. An estimate of Kaklyugin and Norman (Kaklyugin, A.S. and Norman, G.E., 1973 Teplofiz. vysok. temp., vol.11, 238-244) which takes into account both particle correlation and electron localisation in the environment of ions agrees very well with the experimental results over the whole temperature range.

  16. Bifurcation of radial electric field in tokamak edge plasmas due to ion orbit loss

    International Nuclear Information System (INIS)

    Wu, G.J.; Zhang, X.D.

    2015-01-01

    The ion orbit loss and the formation of radial electric field Er in tokamak edge region are calculated. The ion orbit loss generates a negative Er, which in turn affects the ion loss. As a result, Er can saturates at either a low or a high value, depending on the plasma parameters. When the ion temperature in the plasma edge is higher than a threshold a self-sustaining growth in both the ion loss and Er is found, leading to a high saturation value of Er in the milliseconds time. This mechanism provides a possible explanation for the formation of the edge radial electric field during the L to H-mode transition observed in tokamak experiments. (author)

  17. Formation of plasma around wire fragments created by electrically exploded copper wire

    International Nuclear Information System (INIS)

    Taylor, Michael J.

    2002-01-01

    The physical processes occurring during the electrical explosion of metallic conductors has attracted interest for many years. Applications include circuit breakers, segmented lightning divertor strips for aircraft radomes, disruption of metallic shaped charge jets, plasma armatures for electromagnetic railguns and plasma generators for electrothermal-chemical guns. Recent work has cited the phenomenology of the fragmentation processes, particularly the development of a plasma around the lower resistance condensed fragments. An understanding of both the fragmentation process and the development of the accompanying formation of plasma is essential for the optimization of devices that utilize either of these phenomena. With the use of x-radiography and fast photography, this paper explores the wire explosion process, in particular the relationship between the fragmentation, plasma development and resistance rise that occurs during this period. A hypothesis is put forward to account for the development of plasma around the condensed wire fragments. Experimental parameters used in this study are defined. Wires studied were typically copper, with a diameter of 1 mm and length in excess of 150 mm. Circuit inductance used were from 26 to 800 μH. This relatively high circuit inductance gave circuit rise times less than 180 MA s -1 , slow with respect to many other exploding wire studies. Discharge duration ranged from 0.8 to 10 ms. (author)

  18. Optimizing the electrical excitation of an atmospheric pressure plasma advanced oxidation process.

    Science.gov (United States)

    Olszewski, P; Li, J F; Liu, D X; Walsh, J L

    2014-08-30

    The impact of pulse-modulated generation of atmospheric pressure plasma on the efficiency of organic dye degradation has been investigated. Aqueous samples of methyl orange were exposed to low temperature air plasma and the degradation efficiency was determined by absorbance spectroscopy. The plasma was driven at a constant frequency of 35kHz with a duty cycle of 25%, 50%, 75% and 100%. Relative concentrations of dissolved nitrogen oxides, pH, conductivity and the time evolution of gas phase ozone were measured to identify key parameters responsible for the changes observed in degradation efficiency. The results indicate that pulse modulation significantly improved dye degradation efficiency, with a plasma pulsed at 25% duty showing a two-fold enhancement. Additionally, pulse modulation led to a reduction in the amount of nitrate contamination added to the solution by the plasma. The results clearly demonstrate that optimization of the electrical excitation of the plasma can enhance both degradation efficiency and the final water quality. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Electrical conductivity of a fully ionized plasma in a magnetic field

    International Nuclear Information System (INIS)

    Vaucher, B.; Vaclavik, J.; Schneider, H.

    1975-01-01

    In this experimental work the authors have investigated the electrical conductivity of a homogeneous fully ionized plasma in a homogeneous magnetic field. In particular, the conductivity perpendicular to the magnetic field was studied by means of the magnetoacoustic resonance for different values of the parameter ωsub(c)/γsub(ei) where ωsub(c) is the electron cyclotron frequency and γsub(ei) is the collision frequency between electrons and ions. (Auth.)

  20. Transition of radial electric field by electron cyclotron heating in stellarator plasmas

    International Nuclear Information System (INIS)

    Idei, H.; Ida, K.; Sanuki, H.

    1993-06-01

    The transition of a radial electric field from a negative to a positive value is observed in Compact Helical System when the electron loss is sufficiently enhanced by the superposition of the off-axis second harmonic electron cyclotron heating on the neutral beam heated plasmas. The observed threshold for the enhanced particle flux required to cause the transition is compared with a theoretical prediction. (author)

  1. Plasma sprayed manganeseecobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

    Czech Academy of Sciences Publication Activity Database

    Han Jung, S.; Pala, Zdeněk; Sampath, S.

    2016-01-01

    Roč. 304, February (2016), s. 234-243 ISSN 0378-7753 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Interconnect protection * Cr-poisoning * Manganese cobalt spinel * Electrical conductivity * Plasma spray Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use Impact factor: 6.395, year: 2016 http://www.sciencedirect.com/science/article/pii/S0378775315305383

  2. Evaluation of electrical conductivity in high-pressure plasmas formed in xenon with sodium as additive

    Energy Technology Data Exchange (ETDEWEB)

    Novakovic, N V [Faculty of Philosophy, Nis (Yugoslavia); Stojilkovic, S M [Faculty of Electronics, Nis (Yugoslavia); Milic, B S [Dept. of Physics and Meteorology, Faculty of Natural and Mathematical Sciences, Belgrade (Yugoslavia)

    1990-02-01

    Results of a numerical evaluation of the electrical conductivity in high-pressure plasmas of intermediate degrees of ionization formed in xenon with, respectively, 1% and 10% of sodium are presented, for temperatures between 2000 K and 20 000 K, and for pressures ranging from the normal atmospheric value p{sub atm} = 0.1 MPa up to 2.5 MPa. The equilibrium plasma composition, necessary for the evaluations, was determined on the ground of the Saha equations combined with the charge conservation relation and the assumption that the pressure remained constant in the course of temperature variations. The ionization energy lowering, required in conjunction with the Saha equations, was obtained with the aid of a modified expression for the plasma Debye radius proposed previously. The electron elastic collisions with the charged particles were described by the Spitzer-Haerm (or, rather, Rutherford) formula, and those with the neutrals were taken into account by a polynomial formula interpolating some selected experimental results. The evaluated electrical conductivity is found to increase with the pressure at fixed temperature (except in the mixture with 10% of sodium, in which case an indistinct maximum at p = 10 p{sub atm} can be seen for 6000 K). This feature is opposite to what is found in pure xenon plasma and, except in the upper part of the temperature range analysed, agrees well with the behaviour of pure alkaline vapours. The numerical values obtained for the electrical conductivity are smaller than the figures resulting from the approximate formulae commonly used in numerical estimates of this transport coefficient in moderately non-ideal plasmas of intermediate degrees of ionization, much in accordance with the trends suggested by the experiment. (orig.).

  3. Self-generated visual imagery alters the mere exposure effect.

    Science.gov (United States)

    Craver-Lemley, Catherine; Bornstein, Robert F

    2006-12-01

    To determine whether self-generated visual imagery alters liking ratings of merely exposed stimuli, 79 college students were repeatedly exposed to the ambiguous duck-rabbit figure. Half the participants were told to picture the image as a duck and half to picture it as a rabbit. When participants made liking ratings of both disambiguated versions of the figure, they rated the version consistent with earlier encoding more positively than the alternate version. Implications of these findings for theoretical models of the exposure effect are discussed.

  4. Electrically controlled wire-channel GaN/AlGaN transistor for terahertz plasma applications

    Science.gov (United States)

    Cywiński, G.; Yahniuk, I.; Kruszewski, P.; Grabowski, M.; Nowakowski-Szkudlarek, K.; Prystawko, P.; Sai, P.; Knap, W.; Simin, G. S.; Rumyantsev, S. L.

    2018-03-01

    We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

  5. Effects of thruster firings on the shuttle's plasma and electric field environment

    International Nuclear Information System (INIS)

    Machuzak, J.S.; Burke, W.J.; Retterer, J.M.; Hunton, D.E.; Jasperse, J.R.; Smiddy, M.

    1993-01-01

    Simultaneous plasma and AC/DC electric field measurements taken during the space shuttle mission STS-4 at times of prolonged thruster firings are analyzed and cross correlated. Depending on the orientation of the shuttle's velocity vector to the magnetic field, ion densities and electric field wave spectra were enhanced or decreased. The systematic picture of interactions within the shuttle's plasma/neutral gas environment of Cairns and Gurnett (1991b) is confirmed and extended. Waves are excited by outgassed and thruster-ejected molecules that ionize in close proximity to the shuttle. On time scales significantly less than an ion gyroperiod, the newly created ions act as beams in the background plasma. These beams are sources of VLF waves that propagate near the shuttle and intensify during thruster firings. Plasma density depletions and/or the shuttle's geometry may hinder wave detection in the payload bay. A modified two-stream analysis indicates that beam components propagating at large angles to the magnetic field are unstable to the growth of lower hybrid waves. The beam-excited, lower hybrid waves heat some electrons to sufficient energies to produce impact ionization. Empirical evidence for other wave-growth mechanisms outside the lower-hybrid band is presented. 42 refs., 15 figs., 3 tabs

  6. Ionospheric plasma escape by high-altitude electric fields: Magnetic moment ''pumping''

    International Nuclear Information System (INIS)

    Lundin, R.; Hultqvist, B.

    1989-01-01

    Measurements of electric fields and the composition of upward flowing ionospheric ions by the Viking spacecraft have provided further insight into the mass dependent plasma escape process taking place in the upper ionosphere. The Viking results of the temperature and mass-composition of individual ion beams suggest that upward flowing ion beams can be generated by a magnetic moment ''pumping'' mechanism caused by low-frequency transverse electric field fluctuations, in addition to a field aligned ''quasi-electrostatic'' acceleration process. Magnetic moment ''pumping'' within transverse electric field gradients can be described as a conversion of electric drift velocity to cyclotron velocity by the inertial drift in time-dependent electric field. This gives an equal cyclotron velocity gain for all plasma species, irrespective of mass. Oxygen ions thus gain 16 times as much transverse energy as protons. In addition to a transverse energy gain above the escape energy, a field-aligned quasi-electrostatic acceleration is considered primarily responsible for the collimated upward flow of ions. The field-aligned acceleration adds a constant parallel energy to escaping ionospheric ions. Thus, ion beams at high altitudes can be explained by a bimodal acceleration from both a transverse (equal velocity) and a parallel (equal energy) acceleration process. The Viking observations also show that the thermal energy of ion beams, and the ion beam width are mass dependent. The average O + /H + ''temperature ratio has been found to be 4.0 from the Viking observations. This is less than the factor of 16 anticipated from a coherent transverse electric field acceleration but greater than the factor of 1 (or even less than 1) expected from a turbulent acceleration process. copyright American Geophysical Union 1989

  7. Investigation of the electric field structure in ISX-B plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, J.; Hallock, G.A.; Jennings, W.C.; Hickok, R.L.; Wootton, A.J.; Sigmar, D.J.

    1986-04-01

    Plasma potentials have been measured for the first time in neutral-beam-heated tokamak discharges. Radial potential profiles have been obtained for coinjection, counterinjection, and balanced injection discharges as well as for ohmically heated plasmas in the Impurity Study Experiment (ISX-B) tokamak. Within experimental uncertainties, the measured values of potential are consistent with calculations based on radial momentum balance using experimental values of rotation velocities, density, and ion temperature. The measurements were made using a heavy-ion beam probe, with typical plasma conditions of I/sub p/ approx. = 150 kA, B/sub T/ approx. = 12.3 kG, n-bar/sub e/ approx. = 4 x 10/sup 13/ cm/sup -3/, and P/sub b/ approx. = 0.9 MW. A negative potential well depth of about 1.0 kV was observed in ohmically heated plasmas and increased somewhat for balanced injection. Counterinjection resulted in a significantly larger well depth of approximately 3 to 4 kV, while coinjection showed an outward-pointing electric field in the plasma interior. The particle confinement times of both ions and impurities were observed to improve with counterinjection as compared with coinjection.

  8. Investigation of the electric field structure in ISX-B plasmas

    International Nuclear Information System (INIS)

    Mathew, J.; Hallock, G.A.; Jennings, W.C.; Hickok, R.L.; Wootton, A.J.; Sigmar, D.J.

    1986-04-01

    Plasma potentials have been measured for the first time in neutral-beam-heated tokamak discharges. Radial potential profiles have been obtained for coinjection, counterinjection, and balanced injection discharges as well as for ohmically heated plasmas in the Impurity Study Experiment (ISX-B) tokamak. Within experimental uncertainties, the measured values of potential are consistent with calculations based on radial momentum balance using experimental values of rotation velocities, density, and ion temperature. The measurements were made using a heavy-ion beam probe, with typical plasma conditions of I/sub p/ approx. = 150 kA, B/sub T/ approx. = 12.3 kG, n-bar/sub e/ approx. = 4 x 10 13 cm -3 , and P/sub b/ approx. = 0.9 MW. A negative potential well depth of about 1.0 kV was observed in ohmically heated plasmas and increased somewhat for balanced injection. Counterinjection resulted in a significantly larger well depth of approximately 3 to 4 kV, while coinjection showed an outward-pointing electric field in the plasma interior. The particle confinement times of both ions and impurities were observed to improve with counterinjection as compared with coinjection

  9. 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

  10. A rate-equation model for polarized laser-induced fluorescence to measure electric field in glow discharge He plasmas

    International Nuclear Information System (INIS)

    Takiyama, K.; Watanabe, M.; Oda, T.

    1998-01-01

    Possibility of applying polarized laser-induced fluorescence (LIF) spectroscopy for measuring the electric field in a plasma with a large collisional depolarization has been investigated. A rate equation model including the depolarization process was employed to analyze the time evolution of LIF polarization components. The polarized LIF pulse shapes observed in the sheath of a He glow discharge plasma were successfully reproduced, and the electric field distribution was obtained with high accuracy. (author)

  11. Plasma dynamics near an earth satellite and neutralization of its electric charge during electron beam injection into the ionosphere

    International Nuclear Information System (INIS)

    Fedorov, V.A.

    2000-01-01

    A study is made of the dynamics of the ionospheric plasma in the vicinity of an earth satellite injecting an electron beam. The time evolution of the electric charge of the satellite is determined. The electric potential of the satellite is found to be well below the beam-cutoff potential. It is shown that, under conditions typical of active experiments in space, the plasma electrons are capable of neutralizing the satellite's charge

  12. Radial electric field studies in the plasma edge of ASDEX upgrade

    International Nuclear Information System (INIS)

    Viezzer, Eleonora

    2012-01-01

    In magnetically confined fusion plasmas, edge transport barriers (ETBs) are formed during the transition from a highly turbulent state (low confinement regime, L-mode) to a high energy confinement regime (H-mode) with reduced turbulence and transport. The performance of an H-mode fusion plasma is highly dependent on the strength of the ETB which extends typically over the outermost 5% of the confined plasma. The formation of the ETB is strongly connected to the existence of a sheared plasma flow perpendicular to the magnetic field caused by a local radial electric field E r . The gradients in E r and the accompanying E x B velocity shear play a fundamental role in edge turbulence suppression, transport barrier formation and the transition to H-mode. Thus, the interplay between macroscopic flows and transport at the plasma edge is of crucial importance to understanding plasma confinement and stability. The work presented in this thesis is based on charge exchange recombination spectroscopy (CXRS) measurements performed at the plasma edge of the ASDEX Upgrade (AUG) tokamak. During this thesis new high-resolution CXRS diagnostics were installed at the outboard and inboard miplane of AUG, which provide measurements of the temperature, density and flows of the observed species. From these measurements the radial electric field can be directly determined via the radial force balance equation. The new CXRS measurements, combined with the other edge diagnostics available at AUG, allow for an unprecedented, high-accuracy localization (2-3 mm) of the E r profile. The radial electric field has been derived from charge exchange spectra measured on different impurity species including He 2+ , B 5+ , C 6+ and Ne 10+ . The resulting E r profiles are found to be identical within the uncertainties regardless of the impurity species used, thus demonstrating the validity of the diagnostic technique. Inside the ETB the E r profile forms a deep, negative (i.e. directed towards the

  13. Ionization and acoustical instability of a low temperature magnetized plasma in a combined (direct and alternating) electrical field

    International Nuclear Information System (INIS)

    Andropov, V.G.; Sinkevich, O.A.

    1983-01-01

    It is shown that the ionization front which moves through a gas along a magnetic field in a combined electrical field, which lies in the plane of the front, may be unstable, as a result of the development of an ionization instability in the plasma behind the front. The criterion of instability of the ionization front does not greatly differ from the criterion of instability of an infinite plasma. The ionization front in the magnetic field is stable only in an electrical field of circular polarization or in a combined field in which the direct and alternating electrical fields are orthogonal and the Joule heat liberation from them is equal. The generation of sound is possible in a magnetized plasma in an alternating electrical field orthogonal to a magnetic due to the parametric acoustical instability at the frequency of the external electrical field. 8 refs

  14. Comparison of pulsed corona plasma and pulsed electric fields for the decontamination of water containing Legionella pneumophila as model organism.

    Science.gov (United States)

    Banaschik, Robert; Burchhardt, Gerhard; Zocher, Katja; Hammerschmidt, Sven; Kolb, Juergen F; Weltmann, Klaus-Dieter

    2016-12-01

    Pulsed corona plasma and pulsed electric fields were assessed for their capacity to kill Legionella pneumophila in water. Electrical parameters such as in particular dissipated energy were equal for both treatments. This was accomplished by changing the polarity of the applied high voltage pulses in a coaxial electrode geometry resulting in the generation of corona plasma or an electric field. For corona plasma, generated by high voltage pulses with peak voltages of +80kV, Legionella were completely killed, corresponding to a log-reduction of 5.4 (CFU/ml) after a treatment time of 12.5min. For the application of pulsed electric fields from peak voltages of -80kV a survival of log 2.54 (CFU/ml) was still detectable after this treatment time. Scanning electron microscopy images of L. pneumophila showed rupture of cells after plasma treatment. In contrast, the morphology of bacteria seems to be intact after application of pulsed electric fields. The more efficient killing for the same energy input observed for pulsed corona plasma is likely due to induced chemical processes and the generation of reactive species as indicated by the evolution of hydrogen peroxide. This suggests that the higher efficacy and efficiency of pulsed corona plasma is primarily associated with the combined effect of the applied electric fields and the promoted reaction chemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Experimentally obtained values of electric field of an atmospheric pressure plasma jet impinging on a dielectric surface

    NARCIS (Netherlands)

    Sobota, A.; Guaitella, O.; Garcia-Caurel, E.

    2013-01-01

    We report on experimentally obtained values of the electric field magnitude on a dielectric surface induced by an impinging atmospheric pressure plasma jet. The plasma plume was striking the dielectric surface at an angle of 45¿, at 5mm from the surface measured at the axis of the jet. The results

  16. Motion of ionizing electric-field solitons in a bounded plasma

    International Nuclear Information System (INIS)

    Lagar'kov, A.; Rutkevich, I.

    1981-01-01

    A theory is derived for the motion of fast ionization waves along a plane slab of a weakly ionized plasma. The properties of the ionization wave are shown to be closely related to the motion of a two-dimensional surface-charge wave along the slab boundaries. As a result, the ionization wave is quite different from a one-dimensional wave. A quasi-one-dimensional description is used for the wave motion, in which the initial equations are averaged over the transverse coordinate. The relationship between the normal component of the current density at the plasma boundary and the amplitude of the electric potential from the linear theory for a surface wave is used to close the system of averaged equations. Self-similar solutions are derived for these equations; the solutions describe space-charge solitons and electric-field solitons which ionize the plasma. The theory is used to explain the motion of fast ionization waves in long discharge tubes

  17. Statistics on the parameters of nonisothermal ionospheric plasma in large mesospheric electric fields

    Science.gov (United States)

    Martynenko, S.; Rozumenko, V.; Tyrnov, O.; Manson, A.; Meek, C.

    The large V/m electric fields inherent in the mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency at D region altitudes, and consequently the ionospheric plasma in the lower part of the D region undergoes a transition into a nonisothermal state. This study is based on the databases on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude) and with the 2.3-MHz radar of the Kharkiv V. Karazin National University (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented in Meek, C. E., A. H. Manson, S. I. Martynenko, V. T. Rozumenko, O. F. Tyrnov, Remote sensing of mesospheric electric fields using MF radars, Journal of Atmospheric and Solar-Terrestrial Physics, in press. The large mesospheric electric fields is experimentally established to follow a Rayleigh distribution in the interval 0 electrically active mesosphere and the lower ionospheric plasma.

  18. Statistical parameters of nonisothermal lower ionospheric plasma in the electrically active mesosphere

    Science.gov (United States)

    Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.; Manson, A. H.; Meek, C. E.

    The large V/m electric fields inherent in the lower mesosphere play an essential role in lower ionospheric electrodynamics. They must be the cause of large variations in the electron temperature and the electron collision frequency and consequently of the transition of the ionospheric plasma in the lower part of the D region into a nonisothermal state. This study is based on the datasets on large mesospheric electric fields collected with the 2.2-MHz radar of the Institute of Space and Atmospheric Studies, University of Saskatchewan, Canada (52°N geographic latitude, 60.4°N geomagnetic latitude), and with the 2.3-MHz radar of the Kharkiv V. Karazin National University, Ukraine (49.6°N geographic latitude, 45.6°N geomagnetic latitude). The statistical analysis of these data is presented by [Meek, C.E., Manson, A.H., Martynenko, S.I., Rozumenko, V.T., Tyrnov, O.F. Remote sensing of mesospheric electric fields using MF radars. J. Atmos. Solar-Terr. Phys. 66, 881-890, 2004. 10.1016/j.jastp.2004.02.002]. The large mesospheric electric fields in the 60-67-km altitude range are experimentally established to follow a Rayleigh distribution in the 0 < E < 2.5 V/m interval. These data have permitted the resulting differential distributions of relative disturbances in the electron temperature, θ, and the effective electron collision frequency, η, to be determined. The most probable θ and η values are found to be in the 1.4-2.2 interval, and hence the nonstationary state of the lower part of the D region needs to be accounted for in studying processes coupling the electrically active mesosphere and the lower ionospheric plasma.

  19. Efficient Pruning Method for Ensemble Self-Generating Neural Networks

    Directory of Open Access Journals (Sweden)

    Hirotaka Inoue

    2003-12-01

    Full Text Available Recently, multiple classifier systems (MCS have been used for practical applications to improve classification accuracy. Self-generating neural networks (SGNN are one of the suitable base-classifiers for MCS because of their simple setting and fast learning. However, the computation cost of the MCS increases in proportion to the number of SGNN. In this paper, we propose an efficient pruning method for the structure of the SGNN in the MCS. We compare the pruned MCS with two sampling methods. Experiments have been conducted to compare the pruned MCS with an unpruned MCS, the MCS based on C4.5, and k-nearest neighbor method. The results show that the pruned MCS can improve its classification accuracy as well as reducing the computation cost.

  20. Stability and semiclassics in self-generated fields

    DEFF Research Database (Denmark)

    Erdös, Laszlo; Fournais, Søren; Solovej, Jan Philip

    2013-01-01

    We consider non-interacting particles subject to a fixed external potential V and a self-generated magnetic field B. The total energy includes the field energy β∫B^2 and we minimize over all particle states and magnetic fields. In the case of spin-1/2 particles this minimization leads...... measuring the field strength in the semiclassical limit is κ=βh. We are not able to give the exact leading order semiclassical asymptotics uniformly in κ or even for fixed κ. We do however give upper and lower bounds on E with almost matching dependence on κ. In the simultaneous limit h→0 and κ→∞ we show...

  1. Energy loss of ions by electric-field fluctuations in a magnetized plasma.

    Science.gov (United States)

    Nersisyan, Hrachya B; Deutsch, Claude

    2011-06-01

    The results of a theoretical investigation of the energy loss of charged particles in a magnetized classical plasma due to the electric-field fluctuations are reported. The energy loss for a test particle is calculated through the linear-response theory. At vanishing magnetic field, the electric-field fluctuations lead to an energy gain of the charged particle for all velocities. It has been shown that in the presence of strong magnetic field, this effect occurs only at low velocities. In the case of high velocities, the test particle systematically loses its energy due to the interaction with a stochastic electric field. The net effect of the fluctuations is the systematic reduction of the total energy loss (i.e., the sum of the polarization and stochastic energy losses) at vanishing magnetic field and reduction or enhancement at strong field, depending on the velocity of the particle. It is found that the energy loss of the slow heavy ion contains an anomalous term that depends logarithmically on the projectile mass. The physical origin of this anomalous term is the coupling between the cyclotron motion of the plasma electrons and the long-wavelength, low-frequency fluctuations produced by the projectile ion. This effect may strongly enhance the stochastic energy gain of the particle.

  2. Study of thermal and electrical parameters of workpieces during spray coating by electrolytic plasma jet

    International Nuclear Information System (INIS)

    Khafizov, A A; Shakirov, Yu I; Valiev, R A; Valiev, R I; Khafizova, G M

    2016-01-01

    In this paper the results are presented of thermal and electrical parameters of products in the system bottom layer - intermediate layer when applying protective coatings of ferromagnetic powder by plasma spray produced in an electric discharge with a liquid cathode, on steel samples. Temperature distribution and gradients in coating and intermediate coating were examined. Detailed descriptions of spray coating with ferromagnetic powder by plasma jet obtained in electrical discharge with liquid cathode and the apparatus for obtaining thereof is provided. Problem has been solved by using of Fourier analysis. Initial data for calculations is provided. Results of numerical analysis are provided as temporal functions of temperature in contiguity between coating and intermediate coating as well as temporal function of the value Q=q-φ; where q is density of heat current directed to the free surface of intermediate coating, φ is density of heat current in contiguity between coating and intermediate coating. The analysis of data given shows that in the systems of contact heat exchange bottom layer-intermediate layer with close values of the thermophysical characteristics of constituting materials is observed a slow increase of the temperature of the contact as a function of time. (paper)

  3. Structural and electrical characterization of HBr/O2 plasma damage to Si substrate

    International Nuclear Information System (INIS)

    Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya

    2011-01-01

    Silicon substrate damage caused by HBr/O 2 plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H 2 , Ar, and O 2 plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O 2 plasma exposure, hydrogen generated the deep damaged layer (∼10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

  4. Structural and electrical characterization of HBr/O{sub 2} plasma damage to Si substrate

    Energy Technology Data Exchange (ETDEWEB)

    Fukasawa, Masanaga; Nakakubo, Yoshinori; Matsuda, Asahiko; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi; Minami, Masaki; Uesawa, Fumikatsu; Tatsumi, Tetsuya [Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan); Department of Aeronautics and Astronautics, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Semiconductor Technology Development Division, Semiconductor Business Group, Professional, Device and Solutions Group, Sony Corporation, 4-14-1 Asahi-cho, Atsugi-shi, Kanagawa 243-0014 (Japan)

    2011-07-15

    Silicon substrate damage caused by HBr/O{sub 2} plasma exposure was investigated by spectroscopic ellipsometry (SE), high-resolution Rutherford backscattering spectroscopy, and transmission electron microscopy. The damage caused by H{sub 2}, Ar, and O{sub 2} plasma exposure was also compared to clarify the ion-species dependence. Although the damage basically consists of a surface oxidized layer and underlying dislocated Si, the damage structure strongly depends on the incident ion species, ion energy, and oxidation during air and plasma exposure. In the case of HBr/O{sub 2} plasma exposure, hydrogen generated the deep damaged layer ({approx}10 nm), whereas ion-enhanced diffusion of oxygen, supplied simultaneously by the plasma, caused the thick surface oxidation. In-line monitoring of damage thicknesses by SE, developed with an optimized optical model, showed that the SE can be used to precisely monitor damage thicknesses in mass production. Capacitance-voltage (C-V) characteristics of a damaged layer were studied before and after diluted-HF (DHF) treatment. Results showed that a positive charge is generated at the surface oxide-dislocated Si interface and/or in the bulk oxide after plasma exposure. After DHF treatment, most of the positive charges were removed, while the thickness of the ''Si recess'' was increased by removing the thick surface oxidized layer. As both the Si recess and remaining dislocated Si, including positive charges, cause the degradation of electrical performance, precise monitoring of the surface structure and understanding its effect on device performance is indispensable for creating advanced devices.

  5. Oscillations and Stability of Plasma in an External High-Frequency Electric Field

    International Nuclear Information System (INIS)

    Aliev, Ju.M.; Gorbunov, L.M.; Silin, V.P.; Uotson, H.

    1966-01-01

    A theory is developed for the oscillations and stability of plasma in a strong external HF electric field. The kinetic equation with self-congruent reciprocity is linearized for weak deviations from the ground state. Since the latter depends on an external HF field, the linearized equation obtained has coefficients with a periodic time dependence. From this equation and also from Maxwell's equations there is derived a dispersion equation for plasma oscillations that represents the zero value of the infinite order determinant, and that is solved both for external field frequencies considerably exceeding the electron Langmuir frequency and for frequencies that are less. The external HF field changes the oscillation branches in a plasma without an external field, and also leads to a new low-frequency oscillation branch. Movement of particles in the HF field gives spatial dispersion. If the frequency of the field exceeds the election Langmuir frequency, the plasma oscillations are stable. At frequencies less than this level there occurs a build-up of low-frequency oscillations. Here the maximum of the build-up occurs when the external field frequencies approach the electron Langmuir frequency and is equal to the product of the Langmuir frequency and the one-third power of the electron-ion mass ratio. Away from the resonance, -the increment of build-up has the same order of magnitude as the ion Langmuir frequency. An external magnetic field increases the number of possible natural plasma oscillations and thereby increases the possibility of resonance with the external HF field. Allowance for the thermal motion of the particles enables one to determine the attenuation of the oscillations in question. Expressions for the decrements are derived. The effect of the external HF field on a plasma in which there are beams is also discussed. An HF field has a destabilizing effect on a system of this kind, since on the one hand there can be a build-up of fresh, low

  6. On the stability of the interface between dense plasma and liquid under electrical pulse discharge in liquid medium

    International Nuclear Information System (INIS)

    Starchyk, P.D.; Porytskyy, P.V.

    2005-01-01

    It is shown that the most important influence on the plasma of electrical pulse discharges in liquid have the processes in a zone of its contact with condensed medium. The investigations of growth of corrugations are conducted which arise on an interface between both the plasma channels of electrical pulse discharges and limiting it liquid. It is shown that the growth of perturbations caused by Rayleigh-Taylor instability are nonlinearly saturated. It is established the interconnection between both the pointed perturbations and the parameters of a dense plasma of discharge channel

  7. Effects O2 plasma surface treatment on the electrical properties of the ITO substrate

    International Nuclear Information System (INIS)

    Hong, Jin-Woong; Oh, Dong-Hoon; Shim, Sang-Min; Lee, Young-Sang; Kang, Yong-Gil; Shin, Jong-Yeol

    2012-01-01

    The indium-tin-oxide (ITO) substrate is used as a transparent electrode in organic light-emitting diodes (OLEDs) and organic photovoltaic cells. The effect of an O 2 plasma surface treatment on the electrical properties of the ITO substrate was examined. The four-point probe method, an atomic force microscope (AFM), a LCR meter, a Cole-Cole plot, and a conductive mechanism analysis were used to assess the properties of the treated ITO substrates. The four-point probe method and the AFM study revealed a lower ITO surface resistance of 17.6 Ω/sq and an average roughness of 2 nm, respectively, for a substrate treated by a plasma at 250 W for 40 s. The lower surface resistance of the ITO substrate treated at 250 W for 40 s was confirmed by using a LCR meter. An amorphous fluoropolymer (AF) was deposited on an ITO substrate treated under the optimal conditions and on a non-plasma treated ITO substrate as well. The potential barriers for charge injection in these devices were 0.25 eV and 0.15 eV, respectively, indicating a 0.1-eV decrease due to the plasma treatment.

  8. 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.

  9. Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal); Thomas, D. M. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

    2014-04-15

    The method of matched asymptotic expansions is applied to the problem of a collisionless plasma generated by UV illumination localized in a central part of the plasma in the limiting case of small Debye length λ{sub D}. A second-approximation asymptotic solution is found for the double layer positioned at the boundary of the illuminated region and for the un-illuminated plasma for the plane geometry. Numerical calculations for different values of λ{sub D} are reported and found to confirm the asymptotic results. The net integral space charge of the double layer is asymptotically small, although in the plane geometry it is just sufficient to shield the ambipolar electric field existing in the illuminated region and thus to prevent it from penetrating into the un-illuminated region. The double layer has the same mathematical nature as the intermediate transition layer separating an active plasma and a collisionless sheath, and the underlying physics is also the same. In essence, the two layers represent the same physical object: a transonic layer.

  10. The Electrical Properties of Plasma-Deposited Thin Films Derived from Pelargonium graveolens

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Jumaili

    2017-10-01

    Full Text Available Inherently volatile at atmospheric pressure and room temperature, plant-derived precursors present an interesting human-health-friendly precursor for the chemical vapour deposition of thin films. The electrical properties of films derived from Pelargonium graveolens (geranium were investigated in metal–insulator–metal (MIM structures. Thin polymer-like films were deposited using plasma-enhanced synthesis under various plasma input power. The J–V characteristics of thus-fabricated MIM were then studied in order to determine the direct current (DC conduction mechanism of the plasma polymer layers. It was found that the capacitance of the plasma-deposited films decreases at low frequencies (C ≈ 10−11 and remains at a relatively constant value (C ≈ 10−10 at high frequencies. These films also have a low dielectric constant across a wide range of frequencies that decreases as the input RF power increases. The conductivity was determined to be around 10−16–10−17 Ω−1 m−1, which is typical for insulating materials. The Richardson–Schottky mechanism might dominate charge transport in the higher field region for geranium thin films.

  11. Plasma coating of nanoparticles in the presence of an external electric field

    Science.gov (United States)

    Ebadi, Zahra; Pourali, Nima; Mohammadzadeh, Hosein

    2018-04-01

    Film deposition onto nanoparticles by low-pressure plasma in the presence of an external electric field is studied numerically. The plasma discharge fluid model along with surface deposition and heating models for nanoparticles, as well as a dynamics model considering the motion of nanoparticles, are employed for this study. The results of the simulation show that applying external field during the process increases the uniformity of the film deposited onto nanoparticles and leads to that nanoparticles grow in a spherical shape. Increase in film uniformity and particles sphericity is related to particle dynamics that is controlled by parameters of the external field like frequency and amplitude. The results of this work can be helpful to produce spherical core-shell nanoparticles in nanomaterial industry.

  12. Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma.

    Science.gov (United States)

    Yousefi, Razieh; Davis, Allen B; Carmona-Reyes, Jorge; Matthews, Lorin S; Hyde, Truell W

    2014-09-01

    Understanding the agglomeration of dust particles in complex plasmas requires knowledge of basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold-coated mono-disperse spherical melamine-formaldehyde monomers in a radiofrequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining three-dimensional structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, as well as the external electric field, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.

  13. Effects of in situ plasma treatment on optical and electrical properties of index-matched transparent conducting oxide layer

    International Nuclear Information System (INIS)

    Lim, Yong Hwan; Yoo, Hana; Choi, Bum Ho; Kim, Young Baek; Lee, Jong Ho; Shin, Dong Chan

    2010-01-01

    We investigated the effects of in situ plasma-treatment on optical and electrical properties of index-matched indium tin oxide (IMITO) thin film. To render the IMITO-coated surface hydrophilic and study the optical and electrical characteristics, we performed in situ oxygen plasma post-treatment without breaking vacuum. The 94.6% transmittance in the visible wavelength range (400-700 nm) increased on average to 96.4% and the maximum transmittance reached 98% over a broad wavelength range. The surface roughness and sheet resistance improved from 0.9 nm and 200 Ω/sq to 0.0905 nm and 100 Ω/sq, respectively, by in situ plasma post-treatment. We confirmed by contact angle measurement that the hydrophobic IMITO surface was altered to hydrophilic. The improved optical and electrical characteristics of in situ plasma-treated IMITO makes it adequate for high-resolution liquid crystal on silicon displays.

  14. Robe Development for Electrical Conductivity Analysis in an Electron Gun Produced Helium Plasma

    Science.gov (United States)

    Bragg-Sitton, Shannon M.; Bitteker, Leo; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The use of magnetohydrodynamic (MHD) power conversion systems, potentially coupled with a fission power source, is currently being investigated as a driver for an advanced propulsion system, such as a plasma thruster. The efficiency of a MHD generator is strongly dependent on the electrical conductivity of the fluid that passes through the generator; power density increases as fluid conductivity increases. Although traditional MHD flows depend on thermal ionization to enhance the electrical conductivity, ionization due to nuclear interactions may achieve a comparable or improved conductivity enhancement while avoiding many of the limitations inherent to thermal ionization. Calculations suggest that nuclear-enhanced electrical conductivity increases as the neutron flux increases; conductivity of pure He-3 greater than 10 mho/m may be achievable if exposed to a flux greater than 10(exp 12) neutrons/cm2/s.) However, this remains to be demonstrated experimentally. An experimental facility has been constructed at the Propulsion Research Center at the NASA Marshall Space Flight Center, using helium as the test fluid. High energy electrons will be used to simulate the effects of neutron-induced ionization of helium gas to produce a plasma. These experiments will be focused on diagnosis of the plasma in a virtually static system; results will be applied to future tests with a MHD system. Initial experiments will utilize a 50 keV electron gun that can operate at up to a current of 200 micro A. Spreading the electron beam over a four inch diameter window results in an electron flux of 1.5x 10(exp 13) e/sq cm/s. The equivalent neutron flux that would produce the same ionization fraction in helium is 1x10(exp 12) n/sq cm/s. Experiments will simulate the neutron generated plasma modeled by Bitteker, which takes into account the products of thermal neutron absorption in He-3, and includes various ion species in estimating the conductivity of the resulting plasma. Several

  15. Investigation of the residue in an electric rail gun employing a plasma armature

    Science.gov (United States)

    Bauer, D. P.; Barber, J. P.

    1984-01-01

    The performance of dc electric rail guns using plasma-armature-accelerated projectiles was studied. It was found that the initial rail launcher acceleration profile was consistent with the simulation, but that after the projectile had traveled approximately 25 to 30 cm along the gun, a considerable portion of the current in the projectile armature commutated into a secondary current path. Also noted were the lower than expected muzzle velocities. It was proposed that the secondary current path was a relatively high conductivity layer of residue on the launcher bore.

  16. Theoretical transport analysis of density limit with radial electric field in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2010-11-01

    The confinement property in helical toroidal plasmas is clarified. The analysis is performed by use of the one-dimensional transport equations with the effect of the radiative loss and the radial profile of the electric field. The analytical results in the edge region show the steep gradient in the electron temperature, which indicates the transport barrier formation. Because of the rapid increase of the radiative loss at the low electron temperature, the anomalous heat diffusivity is reduced near the edge. Next, the efficiency of the heating power input in the presence of the radiative loss is studied. The scaling of the critical density in helical devices is also derived. (author)

  17. Ambipolarons: Solitary wave solutions for the radial electric field in a plasma

    International Nuclear Information System (INIS)

    Hastings, D.E.; Hazeltine, R.D.; Morrison, P.J.

    1986-01-01

    The ambipolar radial electric field in a nonaxisymmetric plasma can be described by a nonlinear diffusion equation. This equation is shown to possess solitary wave solutions. A model nonlinear diffusion equation with a cubic nonlinearity is studied. An explicit analytic step-like form for the solitary wave is found. It is shown that the solitary wave solutions are linearly stable against all but translational perturbations. Collisions of these solitary waves are studied and three possible final states are found: two diverging solitary waves, two stationary solitary waves, or two converging solitary waves leading to annihilation

  18. Temperature anisotropy in a cyclotron resonance heated tokamak plasma and the generation of poloidal electric field

    International Nuclear Information System (INIS)

    Choe, W.; Ono, M.; Chang, C.S.

    1994-11-01

    The temperature anisotropy generated by cyclotron resonance heating of tokamak plasmas is calculated and the poloidal equilibrium electric field due to the anisotropy is studied. For the calculation of anisotropic temperatures, bounce-averaged Fokker-Planck equation with a bi-Maxwellian distribution function of heated particles is solved, assuming a moderate wave power and a constant quasilinear cyclotron resonance diffusion coefficient. The poloidal electrostatic potential variation is found to be proportional to the particle density and the degree of temperature anisotropy of warm species created by cyclotron resonance heating

  19. Structural, optical and electrical peculiarities of r.f. plasma sputtered indium tin oxide films

    International Nuclear Information System (INIS)

    Boycheva, Sylvia; Sytchkova, Anna Krasilnikova; Grilli, Maria Luisa; Piegari, Angela

    2007-01-01

    In this work the influence of the deposition conditions on the structural, electrical and optical properties of the ITO films was studied. Films were deposited by r.f. plasma sputtering technique in Ar and varying Ar + O 2 gas mixtures, with and without substrate heating. Transmittance and reflectance of the films were measured in the range 350-2500 nm; the refractive index (n) and the extinction coefficient (k) were calculated by the spectral data simulation. The sheet resistance of the films was measured by four-point probe method. X-ray diffraction analysis was performed to study the texture of the films. Threshold behaviour was observed in the optical and electrical properties of ITO films deposited in Ar + O 2 atmosphere at a certain oxygen concentration determined by a fix combination of all other deposition conditions. A schematic diagram for the change of the film properties versus composition was suggested, which explains the obtained results

  20. A holographic method for investigating cylindrical symmetry plasmas resulting from electric discharges

    International Nuclear Information System (INIS)

    Rosu, N.; Ralea, M.; Foca, M.; Iova, I.

    1992-01-01

    A new method based on holographic interferometry in real time with reference fringes for diagnosing gas electric discharges in cylindrical symmetry tubes is presented. A method for obtaining and quantitatively investigating interferograms obtained with a video camera is described. By studying the resulting images frame by frame and introducing the measurements into an adequate computer programme one gets a graphical recording of the radial distribution of the charged particle concentration in the plasma in any region of the tube at a given time, as well as their axial distribution. The real time evolution of certain phenomena occurring in the discharge tube can also be determined by this non-destructive method. The method is used for electric discharges in Ar at average pressures in a discharge tube with hollow cathode effect. (Author)

  1. Auroral electron fluxes induced by static magnetic field aligned electric field and plasma wave turbulence

    International Nuclear Information System (INIS)

    Assis, A.S. de; Silva, C.E. da; Dias Tavares, A. Jr.; Leubner, C.; Kuhn, S.

    2001-07-01

    We have studied the formation of auroral electron fluxes induced by a field aligned dc electric field in the presence of plasma wave turbulence. The effect of the wave spectral shape on the production rate has been considered. This acceleration scheme was modelled by the weak turbulence approach. The electron fluxes for narrow and broad band spectra, in the case of low and high phase velocities, are calculated, and it is found as a general feature, for all modes, that their enhancement is larger the weaker the background electric field, while for its absolute enhancement it is just the opposite. The electron fluxes are enhanced by many orders of magnitude over that without turbulence. It is also shown that the modes enhance the runaway production rate via their Cherenkov dissipation, and that a synergetic effect occurs in the enhancement when more than one mode turbulent is present in the acceleration region. (author)

  2. Mechanical and electrical properties of diamond-like carbon films deposited by plasma source ion implantation

    International Nuclear Information System (INIS)

    Baba, K.; Hatada, R.; Flege, S.; Ensinger, W.

    2009-01-01

    Diamond-like carbon (DLC) films were prepared by a plasma source ion implantation method with superposed negative pulse and negative DC voltage. Acetylene gas was used as working gas for plasma formation. A negative DC voltage and a negative pulse voltage were superposed and applied to the substrate holder. The DC voltage was changed in the range from 0 to -4.8 kV and the pulse voltage was changed from -18 to -13.2 kV. The films were annealed in the range of 200-450 deg. C for 1 h. The surface morphology of the films and the film thickness were observed by atomic force microscopy and scanning electron microscopy. The film structure was characterized by Raman spectroscopy. The hardness of DLC films was evaluated by an indentation method. Measurement of the electrical resistivity was performed using a four-point probe station. Furthermore, a ball-on-disc test with 2 N load was employed to obtain information about the friction properties and sliding wear resistance of the films. The surface of the DLC films was very smooth and featureless. The deposition rate was changed with the DC voltage and pulse conditions. Integrated intensity ratios I D /I G of Raman spectroscopy and electrical resistivity of the DLC films changed with DC voltage. The electrical resistivity decreased with increasing I D /I G ratio. The I D /I G ratio was increased and the electrical resistivity was decreased with annealing temperature owing to graphitization. Very low friction coefficients around 0.05 were obtained for as-deposited films.

  3. Modulation of terahertz generation in dual-color filaments by an external electric field and preformed plasma

    International Nuclear Information System (INIS)

    Li Min; Li An-Yuan; Yuan Shuai; Zeng He-Ping; He Bo-Qu

    2016-01-01

    Terahertz generation driven by dual-color filaments in air is demonstrated to be remarkably enhanced by applying an external electric field to the filaments. As terahertz generation is sensitive to the dual-color phase difference, a preformed plasma is verified efficiently in modulating terahertz radiation from linear to elliptical polarization. In the presence of preformed plasma, a dual-color filament generates terahertz pulses of elliptical polarization and the corresponding ellipse rotates regularly with the change of the preformed plasma density. The observed terahertz modulation with the external electric field and the preformed plasma provides a simple way to estimate the plasma density and evaluate the photocurrent dynamics of the dual-color filaments. It provides further experimental evidence of the photo-current model in governing the dual-color filament driven terahertz generation processes. (paper)

  4. Effects of Hall current and electrical resistivity on the stability of gravitating anisotropic quantum plasma

    Science.gov (United States)

    Bhakta, S.; Prajapati, R. P.

    2018-02-01

    The effects of Hall current and finite electrical resistivity are studied on the stability of uniformly rotating and self-gravitating anisotropic quantum plasma. The generalized Ohm's law modified by Hall current and electrical resistivity is used along with the quantum magnetohydrodynamic fluid equations. The general dispersion relation is derived using normal mode analysis and discussed in the parallel and perpendicular propagations. In the parallel propagation, the Jeans instability criterion, expression of critical Jeans wavenumber, and Jeans length are found to be independent of non-ideal effects and uniform rotation but in perpendicular propagation only rotation affects the Jeans instability criterion. The unstable gravitating mode modified by Bohm potential and the stable Alfven mode modified by non-ideal effects are obtained separately. The criterion of firehose instability remains unaffected due to the presence of non-ideal effects. In the perpendicular propagation, finite electrical resistivity and quantum pressure anisotropy modify the dispersion relation, whereas no effect of Hall current was observed in the dispersion characteristics. The Hall current, finite electrical resistivity, rotation, and quantum corrections stabilize the growth rate. The stability of the dynamical system is analyzed using the Routh-Hurwitz criterion.

  5. Electrical conductivity and shear viscosity of quark gluon plasma in a quasiparticle model

    International Nuclear Information System (INIS)

    Srivastava, P.K.; Mohanty, B.

    2014-01-01

    Relativistic heavy-ion collisions (HIC) have reported the formation of a strongly coupled quark gluon plasma (sQGP). To study the properties of this sQGP is the main focus nowadays. Among these the shear viscosity (η) and electrical conductivity (σ el ) could reflect the transport properties of the medium. By studying the shear viscosity or more specifically shear viscosity to entropy density ratio (η/s), one can understand the nature of interactions among the constituents of the produced medium, it gives a measure of the fluidity. Electrical conductivity represents the linear response of the system to an applied external electric field. The basic question one could ask is that whether the matter created at heavy ion collision experiment is an electrical conductor or an insulator. Recent lattice QCD as well as phenomenological studies have shown that these transport quantities show some kind of minimum in its variation with respect to temperature near the temperature corresponding to the transition from hadronic phase to quark-gluon phase

  6. Simulation of the electric potential and plasma generation coupling in magnetron sputtering discharges

    Science.gov (United States)

    Trieschmann, Jan; Krueger, Dennis; Schmidt, Frederik; Brinkmann, Ralf Peter; Mussenbrock, Thomas

    2016-09-01

    Magnetron sputtering typically operated at low pressures below 1 Pa is a widely applied deposition technique. For both, high power impulse magnetron sputtering (HiPIMS) as well as direct current magnetron sputtering (dcMS) the phenomenon of rotating ionization zones (also referred to as spokes) has been observed. A distinct spatial profile of the electric potential has been associated with the latter, giving rise to low, mid, and high energy groups of ions observed at the substrate. The adherent question of which mechanism drives this process is still not fully understood. This query is approached using Monte Carlo simulations of the heavy particle (i.e., ions and neutrals) transport consistently coupled to a pre-specified electron density profile via the intrinsic electric field. The coupling between the plasma generation and the electric potential, which establishes correspondingly, is investigated. While the system is observed to strive towards quasi-neutrality, distinct mechanisms governing the shape of the electric potential profile are identified. This work is supported by the German Research Foundation (DFG) in the frame of the transregional collaborative research centre TRR 87.

  7. Divertor experiments in a toroidal plasma, with E x B drift due to an applied radial electric field

    International Nuclear Information System (INIS)

    Strait, E.J.

    1979-09-01

    It is proposed that the E x B drift arising from an externally applied electric field could be used in a tokamak or other toroidal magnetic plasma confinement device to remove plasma and impurities from the region near the wall and reduce the amount of plasma striking the wall. This could either augment or replace a conventional magnetic field divertor. Among the possible advantages of this scheme are easy external control over the rate of removal of plasma, more rapid removal than the naturally occurring rate in a magnetic divertor, and simplification of construction if the magnetic divertor is eliminated. Results of several related experiments performed in the Wisconsin Levitated Octupole are presented

  8. 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

  9. Extended plasma channels created by UV laser in air and their application to control electric discharges

    International Nuclear Information System (INIS)

    Zvorykin, V. D.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

    2015-01-01

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×10 11 –1.5×10 13 and 3×10 6 –3×10 11 W/cm 2 , respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 10 9 –10 17 cm −3 , are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied

  10. Discharge current characteristics as an 'electrical method' for glow discharge plasma diagnosis

    International Nuclear Information System (INIS)

    Toma, M.; Paraschivescu, Alina; Morminches, Anisoara

    2001-01-01

    In its simplest form, the glow discharge can be established by passing an electric current through gas between two electrodes. The gas and the electrodes are contained in an insulating envelope. In many technological applications, and not only, the plasma devices are often treated like a black box. There is a series of external parameters or control variables which can be adjusted to obtain a desired effect, namely, the operating voltage, gas pressure, gas nature, gas flow rate, magnetic field strength and magnetic field configuration, electric field geometry, interelectrode distance, and cathode characteristics. The discharge current can be controlled by each of the above control variables. The core idea of this work is the following: a lot of information about the phenomena from the discharge volume, at electrodes or at the discharge bounding wall surface, can be obtained knowing how the change of one of the control parameters influences the discharge current. The following regimes were analyzed: dark discharges (background ionization, saturation regime, Townsend regime, corona regime), glow discharge (the normal and abnormal discharge) and arc discharge (glow to arc transition, non-thermal arcs, thermal arcs). It was concluded that the nonlinearity in the shape of the discharge current characteristics as a function of an external control parameter, can be correlated with the elementary processes and the dynamics of different space charge structures generated in plasma devices. (authors)

  11. Deposition of titanium nitride layers by electric arc – Reactive plasma spraying method

    International Nuclear Information System (INIS)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Highlights: ► Titanium nitride layers deposited by electric arc – reactive plasma spraying method. ► Deposition of titanium nitride layers on C45 steel at different spraying distances. ► Characterization of the coatings hardness as function of the spraying distances. ► Determination of the corrosion behavior of titanium nitride layers obtained. - Abstract: Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti 2 N) and small amounts of Ti 3 O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  12. PREFACE: 1st International Symposium on Electrical Arc and Thermal Plasmas in Africa (ISAPA)

    Science.gov (United States)

    Andre, Pascal; Koalaga, Zacharie

    2012-02-01

    Logos of the University of Ouagadougou, ISAPA and Universite Blaise Pascal Africa (especially Sub-Saharan Africa) is a continent where electrification is at a low level. However, the development of the electrical power sector is a prerequisite for the growth of other industrial activities, that is to say for the social and economic development of African countries. Consequently, a large number of electrification projects (rural electrification, interconnection of different country's grids) takes place in many countries. These projects need expertise and make Africa a continent of opportunity for companies in different domains for business and research: energy; energetic production, transmission, distribution and protection of electricity; the supply of cable; the construction, engineering and expertise in the field of solar and wind power. The first International Symposium on electrical Arc and thermal Plasma in Africa (ISAPA) was held for the first time in Ouagadougou, Burkina Faso to progress and develop the research of new physical developments, technical breakthroughs, and ideas in the fields of electrical production and electrical applications. The ISAPA aims to encourage the advancement of the science and applications of electrical power transformation in Africa by bringing together specialists from many areas in Africa and the rest of the world. Such considerations have led us to define a Scientific Committee including representatives from many countries. This first meeting was an innovative opportunity for researchers and engineers from academic and industrial sectors to exchange views and knowledge. Both fundamental aspects such as thermal plasma, electrical arc, diagnostics and applied aspects as circuit breakers, ICP analyses, photovoltaic energy conversion and alternative energies, as well as space applications were covered. The Laboratory of Material and Environment (LAME) from Ouagadougou University and the Laboratory of Electric Arc and Thermal

  13. The history of re-connection and the concept of the solar wind plasma with relatively small electrical conductivity

    Science.gov (United States)

    Chertkov, A. D.

    1995-01-01

    Petschek's 're-connection' model, aspiring to be universal, treated as a boundary problem meets unresolvable difficulties connected with impossibility to specify correctly boundary and initial conditions. This problem was incorrectly formulated. Hence, ineradicable logarithmic singularities occurred on the boundary surfaces. Attempts to eliminate them by incorporating the finite electrical conductivity are incorrect. This should lead to the change in the equation type, boundary condition type and in consequence to the change in solutions. Besides, the slow mode shocks cannot be driven by small internal source. As an alternative a new plasma concept is suggested. The state of fully ionized plasma in space depends completely on the entropy of the plasma heating source and on the process in which plasma is involved. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma should be very far from the thermodynamic equilibrium. Debye's screening is not complete. The excitation of the powerful resonant self-consistent electric fields in plasma provides low electric conductivity. The MHD problems should be treated in frameworks of dissipative theories.

  14. Electrical description of a magnetic pole enhanced inductively coupled plasma source: Refinement of the transformer model by reverse electromagnetic modeling

    International Nuclear Information System (INIS)

    Meziani, T.; Colpo, P.; Rossi, F.

    2006-01-01

    The magnetic pole enhanced inductively coupled source (MaPE-ICP) is an innovative low-pressure plasma source that allows for high plasma density and high plasma uniformity, as well as large-area plasma generation. This article presents an electrical characterization of this source, and the experimental measurements are compared to the results obtained after modeling the source by the equivalent circuit of the transformer. In particular, the method applied consists in performing a reverse electromagnetic modeling of the source by providing the measured plasma parameters such as plasma density and electron temperature as an input, and computing the total impedance seen at the primary of the transformer. The impedance results given by the model are compared to the experimental results. This approach allows for a more comprehensive refinement of the electrical model in order to obtain a better fitting of the results. The electrical characteristics of the system, and in particular the total impedance, were measured at the inductive coil antenna (primary of the transformer). The source was modeled electrically by a finite element method, treating the plasma as a conductive load and taking into account the complex plasma conductivity, the value of which was calculated from the electron density and electron temperature measurements carried out previously. The electrical characterization of the inductive excitation source itself versus frequency showed that the source cannot be treated as purely inductive and that the effect of parasitic capacitances must be taken into account in the model. Finally, considerations on the effect of the magnetic core addition on the capacitive component of the coupling are made

  15. Effect of Samarium Oxide on the Electrical Conductivity of Plasma-Sprayed SOFC Anodes

    Science.gov (United States)

    Panahi, S. N.; Samadi, H.; Nemati, A.

    2016-10-01

    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is important that the other components perform at the same temperature. Currently, the anodes of SOFCs are being studied in depth. Research has indicated that anodes based on a perovskite structure are a more promising candidate in SOFCs than the traditional system because they possess more favorable electrical properties. Among the perovskite-type oxides, SrTiO3 is one of the most promising compositions, with studies demonstrating that SrTiO3 exhibits particularly favorable electrical properties in contrast with other perovskite-type oxides. The main purpose of this article is to describe our study of the effect of rare-earth dopants with a perovskite structure on the electrical behavior of anodes in SOFCs. Sm2O3-doped SrTiO3 synthesized by a solid-state reaction was coated on substrate by atmospheric plasma spray. To compare the effect of the dopant on the electrical conductivity of strontium titanate, different concentrations of Sm2O3 were used. The samples were then investigated by x-ray diffraction, four-point probe at various temperatures (to determine the electrical conductivity), and a scanning electron microscope. The study showed that at room temperature, nondoped samples have a higher electrical resistance than doped samples. As the temperature was increased, the electrical

  16. Formation of electron-root radial electric field and its effect on thermal transport in LHD high Te plasma

    International Nuclear Information System (INIS)

    Matsuoka, Seikichi; Satake, Shinsuke; Takahashi, Hiromi; Yokoyama, Masayuki; Ido, Takeshi; Shimizu, Akihiro; Shimozuma, Takashi; Wakasa, Arimitsu; Murakami, Sadayoshi

    2013-01-01

    Neoclassical transport analyses have been performed for a high electron temperature LHD plasma with steep temperature gradient using a neoclassical transport simulation code, FORTEC-3D. It is shown that the large positive radial electric field is spontaneously formed at the core along with the increase in the electron temperature, while the neoclassical heat diffusivity remains almost unchanged. This indicates that the 1/ν-type increase expected in the neoclassical transport in helical plasmas can be avoided by the spontaneous formation of the radial electric field. At the same time, it is found that the experimentally estimated heat diffusivity is significantly reduced. This suggests that the formation process of the transport barrier in the high electron temperature plasma can be caused by the spontaneous formation of the radial electric field. (author)

  17. Using hydrocarbon as a carbon source for synthesis of carbon nanotube by electric field induced needle-pulsed plasma

    International Nuclear Information System (INIS)

    Kazemi Kia, Kaveh; Bonabi, Fahimeh

    2013-01-01

    In this work different hydrocarbons are used as the carbon source, in the production of carbon nanotubes (CNTs) and nano onions. An electric field induced needle pulse arc-discharge reactor is used. The influence of starting carbon on the synthesis of CNTs is investigated. The production efficiency is compared for Acetone, Isopropanol and Naphthalene as simple hydrocarbons. The hydrocarbons are preheated and then pretreated by electric field before being exposed to plasma. The hydrocarbon vapor is injected into plasma through a graphite spout in the cathode assembly. The pulsed plasma takes place between two graphite rods while a strong electric field has been already established alongside the electrodes. The pulse width is 0.3 μs. Mechanism of precursor decomposition is discussed by describing three forms of energy that are utilized to disintegrate the precursor molecules: thermal energy, electric field and kinetic energy of plasma. Molecular polarity of a hydrocarbon is one of the reasons for choosing carbon raw material as a precursor in an electric field induced low power pulsed-plasma. The results show that in order to obtain high quality carbon nanotubes, Acetone is preferred to Isopropanol and Naphthalene. Scanning probe microscopy techniques are used to investigate the products. - Highlights: • We synthesized CNTs (carbon nano tubes) by needle pulsed plasma. • We use different hydrocarbons as carbon source in the production of CNTs. • We investigated the influence of starting carbon on the synthesis of CNTs. • Thermal energy, electric field and kinetic energy are used to break carbon bonds. • Polar hydrocarbon molecules are more efficient than nonpolar ones in production

  18. Radial electric field studies in the plasma edge of ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Viezzer, Eleonora

    2012-12-18

    In magnetically confined fusion plasmas, edge transport barriers (ETBs) are formed during the transition from a highly turbulent state (low confinement regime, L-mode) to a high energy confinement regime (H-mode) with reduced turbulence and transport. The performance of an H-mode fusion plasma is highly dependent on the strength of the ETB which extends typically over the outermost 5% of the confined plasma. The formation of the ETB is strongly connected to the existence of a sheared plasma flow perpendicular to the magnetic field caused by a local radial electric field E{sub r}. The gradients in E{sub r} and the accompanying E x B velocity shear play a fundamental role in edge turbulence suppression, transport barrier formation and the transition to H-mode. Thus, the interplay between macroscopic flows and transport at the plasma edge is of crucial importance to understanding plasma confinement and stability. The work presented in this thesis is based on charge exchange recombination spectroscopy (CXRS) measurements performed at the plasma edge of the ASDEX Upgrade (AUG) tokamak. During this thesis new high-resolution CXRS diagnostics were installed at the outboard and inboard miplane of AUG, which provide measurements of the temperature, density and flows of the observed species. From these measurements the radial electric field can be directly determined via the radial force balance equation. The new CXRS measurements, combined with the other edge diagnostics available at AUG, allow for an unprecedented, high-accuracy localization (2-3 mm) of the E{sub r} profile. The radial electric field has been derived from charge exchange spectra measured on different impurity species including He{sup 2+}, B{sup 5+}, C{sup 6+} and Ne{sup 10+}. The resulting E{sub r} profiles are found to be identical within the uncertainties regardless of the impurity species used, thus demonstrating the validity of the diagnostic technique. Inside the ETB the E{sub r} profile forms a deep

  19. Influence of O2 or H2O in a plasma jet and its environment on plasma electrical and biochemical performances

    Science.gov (United States)

    Adhikari, Ek R.; Samara, Vladimir; Ptasinska, Sylwia

    2018-05-01

    Because environmental conditions, such as room temperature and humidity, fluctuate arbitrarily, effects of atmospheric pressure plasma jets (APPJs) used in medical applications operating at various places and time might vary. Therefore, understanding the possible effects of air components in and outside APPJs is essential for clinical use, which requires reproducibility of plasma performance. These air components can influence the formation of reactive species in the APPJ, and the type and amount of these species formed depend on the feed gas inside the APPJ and the plasma jet environment. In this study, we monitored changes in plasma current and power, as well as in the level of DNA damage attributable to plasma irradiation, by adjusting the fraction of oxygen and water vapor in the plasma jet environment and feed gas. Here, DNA was used as a molecular probe to identify chemical changes that occurred in the plasma jet under these various environmental conditions. The damaged and undamaged fractions of DNA were quantified using agarose gel electrophoresis. We obtained an optimal amount of oxygen or water vapor in the plasma jet environment, as well as in the feed gas, which increased the level of DNA damage significantly. This increase can be attributed primarily to the formation of reactive species caused by water and oxygen decomposition in the APPJ detected with mass spectrometry. Moreover, we observed that the plasma power remained the same or decreased when gas was added to the jet environment or the feed gas, respectively, but in both cases, DNA damage increased. This indicates the superiority of plasma chemistry over the electrical power applied for APPJ ignition of the plasma sources used in medical applications.

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

    International Nuclear Information System (INIS)

    C.A. Ordonez

    1999-01-01

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

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

    International Nuclear Information System (INIS)

    Ordonez, C. A.

    1999-01-01

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

  2. Plasma chemical and electrical modelling of a negative DC corona in pure oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Soria, C [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Pontiga, F [Departamento de FIsica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Castellanos, A [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain)

    2004-02-01

    A complex plasma chemical and electrical model of a negative stationary wire-to-cylinder corona discharge in pure oxygen is presented. The corona discharge is assumed to have axial and azimuthal symmetry. The experimental current-voltage characteristic is required as input data, but there are no other adjustable or empirical parameters. The experimental validation of the results of the model comes from its prediction of the ozone concentration. The role played by different reactions and species is analysed in detail using the results of the simulation. The effect of the gas temperature and of the decomposition of ozone at the electrodes is also investigated. The agreement between the model and the experiments is excellent when the effect of ozone decomposition at the electrodes is taken into account.

  3. Rocket measurements within a polar cap arc - Plasma, particle, and electric circuit parameters

    Science.gov (United States)

    Weber, E. J.; Ballenthin, J. O.; Basu, S.; Carlson, H. C.; Hardy, D. A.; Maynard, N. C.; Kelley, M. C.; Fleischman, J. R.; Pfaff, R. F.

    1989-01-01

    Results are presented from the Polar Ionospheric Irregularities Experiment (PIIE), conducted from Sondrestrom, Greenland, on March 15, 1985, designed for an investigation of processes which lead to the generation of small-scale (less than 1 km) ionospheric irregularities within polar-cap F-layer auroras. An instrumented rocket was launched into a polar cap F layer aurora to measure energetic electron flux, plasma, and electric circuit parameters of a sun-aligned arc, coordinated with simultaneous measurements from the Sondrestrom incoherent scatter radar and the AFGL Airborne Ionospheric Observatory. Results indicated the existence of two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability.

  4. Study on the plasma reaction process of hydroxyl generation by strong electric field ionization discharge

    International Nuclear Information System (INIS)

    Bai Mindi; Deng Shufang; Bai Xiyao; Zhang Zhitao

    2004-01-01

    Considering the change in the structure of reaction room, dielectric materials and process technology, authors have specifically studied the plasma reaction process of creating hydroxyl radical OH * and e aq - from ionization of O 2 and H 2 O through a strong electric field discharge. The production volume of hydroxyl radical OH * is up to the project application level, and process technology meets the 12 laws of green chemistry, free from environmental pollution from the source. The authors have emphatically researched on the green method of flue gas desulfurization, which will ionize SO 2 , H 2 O and O 2 in the flue gas to synthesis H 2 SO 4 in molecular level within 0.8 s without absorbent and catalyst. (author)

  5. Experimental characterization of plasma formation and shockwave propagation induced by high power pulsed underwater electrical discharge.

    Science.gov (United States)

    Claverie, A; Deroy, J; Boustie, M; Avrillaud, G; Chuvatin, A; Mazanchenko, E; Demol, G; Dramane, B

    2014-06-01

    High power pulsed electrical discharges into liquids are investigated for new industrial applications based on the efficiency of controlled shock waves. We present here new experimental data obtained by combination of detailed high speed imaging equipments. It allows the visualization of the very first instants of plasma discharge formation, and then the pulsations of the gaseous bubble with an accurate timing of events. The time history of the expansion/compression of this bubble leads to an estimation of the energy effectively transferred to water during the discharge. Finally, the consecutive shock generation driven by this pulsating bubble is optically monitored by shadowgraphs and schlieren setup. These data provide essential information about the geometrical pattern and chronometry associated with the shock wave generation and propagation.

  6. Plasma chemical and electrical modelling of a negative DC corona in pure oxygen

    International Nuclear Information System (INIS)

    Soria, C; Pontiga, F; Castellanos, A

    2004-01-01

    A complex plasma chemical and electrical model of a negative stationary wire-to-cylinder corona discharge in pure oxygen is presented. The corona discharge is assumed to have axial and azimuthal symmetry. The experimental current-voltage characteristic is required as input data, but there are no other adjustable or empirical parameters. The experimental validation of the results of the model comes from its prediction of the ozone concentration. The role played by different reactions and species is analysed in detail using the results of the simulation. The effect of the gas temperature and of the decomposition of ozone at the electrodes is also investigated. The agreement between the model and the experiments is excellent when the effect of ozone decomposition at the electrodes is taken into account

  7. Onset of the radial electric field oscillations in the neoclassical plasmas

    International Nuclear Information System (INIS)

    Liu, C.S.; Novakovskii, S.V.; Sagdeev, R.Z.; Galeev, A.A.

    1996-01-01

    It is shown that the relaxation of the radial electric field in the tokomak plasmas towards its neoclassical value is accompanied by the fast oscillations of the order of the ion transient frequency V T /qR. This happens during the transition from the Pfirsch-Schluter collisional regime to the plateau regime at v c qR/V T ≤ c cr ≤ 1. The investigation has been performed with the help of the specially developed numerical code for solution of the nonsteady-state drift kinetic equation with the exact collisional term in the Hirshman-Sigmar-Clarke form. Comparison with the analytical results, corresponding to the regime of the very low collisions as well as with previous approximate models for the plateau regime will also be reported

  8. Electric dipole radiation at VLF in a uniform warm magneto-plasma.

    Science.gov (United States)

    Wang, T. N. C.; Bell, T. F.

    1972-01-01

    Use of a linear full electromagnetic wave theory to calculate the input impedance of an electric antenna embedded in a uniform, lossless, unbounded warm magnetoplasma, which is assumed to consist of warm electrons and cold ions. In calculating the dipole radiation resistance for the thermal modes and the thermally modified whistler mode the analysis includes the finite temperature only for the electrons. In deriving the formal solution of the warm plasma dipole input impedance a full-wave analysis is used and two antenna orientations are considered, parallel and perpendicular to the static magnetic field. A general dispersion equation governing the modes of propagation is derived and a detailed analysis is made of the propagation characteristics of these modes.

  9. Electric Field and Plasma Density Observations of Irregularities and Plasma Instabilities in the Low Latitude Ionosphere Gathered by the C/NOFS Satellite

    Science.gov (United States)

    Pfaff, Robert F.; Freudenreich, H.; Rowland, D.; Klenzing, J.; Liebrecht, C.

    2012-01-01

    The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed measurements of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations gathered on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The talk focuses on occasions where the ionosphere F-peak has been elevated above the C/NOFS satellite perigee of 400 km as solar activity has increased. In particular, during the equinox periods of 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set: The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second result is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is near or below the F-peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field

  10. Modifications of plasma edge electric field and confinement properties by limiter biasing on the KT-5C tokamak

    International Nuclear Information System (INIS)

    Hui Gao; Kan Zhai; Yizhi Wen; Shude Wan; Guiding Wang; Changxun Yu

    1995-01-01

    Experiments using a biased multiblock limiter in the KT-5C tokamak show that positive biasing is more effective than negative biasing in modifying the edge electric field, suppressing fluctuations and improving plasma confinement. The biasing effect varies with the limiter area, the toroidal magnetic field and the biasing voltage. By positive biasing, the edge profiles of the plasma potential, the electron temperature and the density become steeper, resulting in a reduced edge particle flux, an increased global particle confinement time and lower fluctuation levels of the edge plasma. (author)

  11. Measurement of the non-thermal properties of a low pressure spraying plasma by electric and spectroscopic methods

    International Nuclear Information System (INIS)

    Jung, Yong Ho

    2003-02-01

    For the case of an atmospheric plasma, the local thermodynamic equilibrium (LTE) model can be applied to plasmas at a nozzle entrance and to those on the axis of the plasma flame, but it is not easy to justify applying the LTE model to off-center plasma and to a low-pressure spraying plasma. Although the energy distribution of the electrons is assumed to be Maxwellian for the most of spraying plasmas, the non-Maxwellian distribution is possible for the case of low-pressure spaying plasma and edge plasma of atmospheric spraying plasma. In this work, the non-Maxwellian distribution of electrons was measured by using an electric probe installed on the fast scanning probe system, and non-LTE effects were measured by using the optical emission spectroscopy system. Distribution of the electrons of a low-pressure spraying plasma is observed not as Maxwellian but as bi-Maxwellian by the measurement of the single probe. Bi-Maxwellian distribution appears in the edge of a low pressure spraying plasma and seems to be due to the reduction of the collisonality by the drastic variation of the plasma density. Non-LTE characteristics of a low-pressure spraying plasma can be deuced from the measured results of the optical emission spectroscopy and is analyzed by the collisional radiative equilibrium (CRE) model, where the Maxwellian and the non-Maxwellian distributions are assumed for comparison. For the electron temperature, the results from optical emission spectroscopy were similar to the results from the single probe (3∼5 % in error)

  12. The wandering self : Tracking distracting self-generated thought in a cognitively demanding context

    NARCIS (Netherlands)

    Huijser, Stefan; van Vugt, Marieke K; Taatgen, Niels A

    We investigated how self-referential processing (SRP) affected self-generated thought in a complex working memory task (CWM) to test the predictions of a computational cognitive model. This model described self-generated thought as resulting from competition between task- and distracting processes,

  13. 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

  14. Turbulence in tokamak plasmas. Effect of a radial electric field shear; Turbulence dans les plasmas de tokamaks. Effet d`un cisaillement de champ electrique radial

    Energy Technology Data Exchange (ETDEWEB)

    Payan, J

    1994-05-01

    After a review of turbulence and transport phenomena in tokamak plasmas and the radial electric field shear effect in various tokamaks, experimental measurements obtained at Tore Supra by the means of the ALTAIR plasma diagnostic technique, are presented. Electronic drift waves destabilization mechanisms, which are the main features that could describe the experimentally observed microturbulence, are then examined. The effect of a radial electric field shear on electronic drift waves is then introduced, and results with ohmic heating are studied together with relations between turbulence and transport. The possible existence of ionic waves is rejected, and a spectral frequency modelization is presented, based on the existence of an electric field sheared radial profile. The position of the inversion point of this field is calculated for different values of the mean density and the plasma current, and the modelization is applied to the TEXT tokamak. The radial electric field at Tore Supra is then estimated. The effect of the ergodic divertor on turbulence and abnormal transport is then described and the density fluctuation radial profile in presence of the ergodic divertor is modelled. 80 figs., 120 refs.

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

    Science.gov (United States)

    DeBlauw, Bradley G.

    The current project was undertaken to evaluate the effects of electric arc plasma actuators on high-speed separated flows. Two underlying goals motivated these experiments. The first goal was to provide a flow control technique that will result in enhanced flight performance for supersonic vehicles by altering the near-wake characteristics. The second goal was to gain a broader and more sophisticated understanding of these complex, supersonic, massively-separated, compressible, and turbulent flow fields. The attainment of the proposed objectives was facilitated through energy deposition from multiple electric-arc plasma discharges near the base corner separation point. The control authority of electric arc plasma actuators on a supersonic axisymmetric base flow was evaluated for several actuator geometries, frequencies, forcing modes, duty cycles/on-times, and currents. Initially, an electric arc plasma actuator power supply and control system were constructed to generate the arcs. Experiments were performed to evaluate the operational characteristics, electromagnetic emission, and fluidic effect of the actuators in quiescent ambient air. The maximum velocity induced by the arc when formed in a 5 mm x 1.6 mm x 2 mm deep cavity was about 40 m/s. During breakdown, the electromagnetic emission exhibited a rise and fall in intensity over a period of about 340 ns. After breakdown, the emission stabilized to a near-constant distribution. It was also observed that the plasma formed into two different modes: "high-voltage" and "low-voltage". It is believed that the plasma may be switching between an arc discharge and a glow discharge for these different modes. The two types of plasma do not appear to cause substantial differences on the induced fluidic effects of the actuator. In general, the characterization study provided a greater fundamental understanding of the operation of the actuators, as well as data for computational model comparison. Preliminary investigations

  16. Comparison of several algorithms of the electric force calculation in particle plasma models

    International Nuclear Information System (INIS)

    Lachnitt, J; Hrach, R

    2014-01-01

    This work is devoted to plasma modelling using the technique of molecular dynamics. The crucial problem of most such models is the efficient calculation of electric force. This is usually solved by using the particle-in-cell (PIC) algorithm. However, PIC is an approximative algorithm as it underestimates the short-range interactions of charged particles. We propose a hybrid algorithm which adds these interactions to PIC. Then we include this algorithm in a set of algorithms which we test against each other in a two-dimensional collisionless magnetized plasma model. Besides our hybrid algorithm, this set includes two variants of pure PIC and the direct application of Coulomb's law. We compare particle forces, particle trajectories, total energy conservation and the speed of the algorithms. We find out that the hybrid algorithm can be a good replacement of direct Coulomb's law application (quite accurate and much faster). It is however probably unnecessary to use it in practical 2D models.

  17. Plasma diagnostics by electron guns and electric field probes on ISEE-1

    International Nuclear Information System (INIS)

    Pedersen, A.

    1982-01-01

    The use of electron guns to control the potential of a satellite with conductive surfaces is discussed with reference to the results of the ISEE-1 satellite experiment. The two electron guns carried by the satellite can emit electrons with energies up to 48 eV, and the emitted electron current has a maximum value of 0.5-1.0 mA. The satellite potential, with or without gun operation, can be measured with reference to one or two spherical electric field probes positioned on booms at a distance of 36 m from the satellite. The probes are biased with a negative current from a high-impedance source to be slightly positive (0.5-1.0 V) relative to the plasma, and the spacecraft is normally several volts more positive and can be further positively charged by operating the electron gun. Plasma diagnostics can be carried out by appropriate sweeps of gun currents and energy of emitted electrons to obtain information about density and characteristic energy of ambient electrons. 9 references

  18. Electric potential structures and propagation of electron beams injected from a spacecraft into a plasma

    International Nuclear Information System (INIS)

    Singh, Nagendra; Hwang, K.S.

    1988-01-01

    The propagation of electron beams injected from a spacecraft into an ambient plasma and the associated potential structures are investigated by one-dimensional Vlasov simulations. For moderate beams, for which the time average spacecraft potential (Φ sa ) lies in the range T e much-lt eΦ sa approx-lt W B , where T e is the electron temperature in energy units and W B is the average beam energy, a double layer forms near the beam head which propagates into the ambient plasma much more slowly than the initial beam velocity. The double layer formation is being reported for the first time. For weak beams, for which |eΦ sa | approx-lt T e , the beam propagates with the initial beam velocity, and no double layer formation occurs. On the other hand, for strong beams for which eΦ sa > W B , the bulk of the beam is returned to the spacecraft, and the main feature of the potential structure is a sheath formation with an intense electric field limited to distances d near the spacecraft surface. These features of the potential structures are compared with those seen in laboratory and space experiments on electron beam injections

  19. Effect of Plasma Membrane Semipermeability in Making the Membrane Electric Double Layer Capacitances Significant.

    Science.gov (United States)

    Sinha, Shayandev; Sachar, Harnoor Singh; Das, Siddhartha

    2018-01-30

    Electric double layers (or EDLs) formed at the membrane-electrolyte interface (MEI) and membrane-cytosol interface (MCI) of a charged lipid bilayer plasma membrane develop finitely large capacitances. However, these EDL capacitances are often much larger than the intrinsic capacitance of the membrane, and all of these capacitances are in series. Consequently, the effect of these EDL capacitances in dictating the overall membrane-EDL effective capacitance C eff becomes negligible. In this paper, we challenge this conventional notion pertaining to the membrane-EDL capacitances. We demonstrate that, on the basis of the system parameters, the EDL capacitance for both the permeable and semipermeable membranes can be small enough to influence C eff . For the semipermeable membranes, however, this lowering of the EDL capacitance can be much larger, ensuring a reduction of C eff by more than 20-25%. Furthermore, for the semipermeable membranes, the reduction in C eff is witnessed over a much larger range of system parameters. We attribute such an occurrence to the highly nonintuitive electrostatic potential distribution associated with the recently discovered phenomena of charge-inversion-like electrostatics and the attainment of a positive zeta potential at the MCI for charged semipermeable membranes. We anticipate that our findings will impact the quantification and the identification of a large number of biophysical phenomena that are probed by measuring the plasma membrane capacitance.

  20. Electrical properties of fluorine-doped ZnO nanowires formed by biased plasma treatment

    Science.gov (United States)

    Wang, Ying; Chen, Yicong; Song, Xiaomeng; Zhang, Zhipeng; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2018-05-01

    Doping is an effective method for tuning electrical properties of zinc oxide nanowires, which are used in nanoelectronic devices. Here, ZnO nanowires were prepared by a thermal oxidation method. Fluorine doping was achieved by a biased plasma treatment, with bias voltages of 100, 200, and 300 V. Transmission electron microscopy indicated that the nanowires treated at bias voltages of 100 and 200 V featured low crystallinity. When the bias voltage was 300 V, the nanowires showed single crystalline structures. Photoluminescence measurements revealed that concentrations of oxygen and surface defects decreased at high bias voltage. X-ray photoelectron spectroscopy suggested that the F content increased as the bias voltage was increased. The conductivity of the as-grown nanowires was less than 103 S/m; the conductivity of the treated nanowires ranged from 1 × 104-5 × 104, 1 × 104-1 × 105, and 1 × 103-2 × 104 S/m for bias voltage treatments at 100, 200, and 300 V, respectively. The conductivity improvements of nanowires formed at bias voltages of 100 and 200 V, were attributed to F-doping, defects and surface states. The conductivity of nanowires treated at 300 V was attributed to the presence of F ions. Thus, we provide a method of improving electrical properties of ZnO nanowires without altering their crystal structure.

  1. On the pulsating electric wind of a Single Dielectric Barrier Discharge (SDBD) plasma actuator

    Science.gov (United States)

    Vernet, Julie; Örlü, Ramis; Alfredsson, P. Henrik

    2014-11-01

    An experimental study is conducted on the electric wind produced by a Single Dielectric Barrier Discharge (SDBD) plasma actuator placed at the top of a half cylinder. Laser Doppler Velocimetry (LDV) measurements were performed and results show that increasing the driving voltage (6-16 kV peak-to-peak) and frequency (0.5-2 kHz) of the actuator increases the induced jet velocity (up to 4 m/s) and thus the momentum added by the actuator. The focus of the present study is on the phase-resolved behavior of the electric wind, in particular, its two strokes. Phase-averaged LDV data reveals that while the velocity during both strokes remains positive, there is nearly a factor of two in amplitude. The difference of behavior between the two strokes and its downstream and wall-normal evolution are mapped for various driving voltages. Results indicate that this difference is restricted to the vicinity of the actuator, thereby justifying the assumption of a steady force in simulations to model the induced force. The study is part of a larger investigation aiming at separation control on the A-pillar of a truck cabin. The support of the Swedish Energy Agency and SCANIA CV of the project Flow Research on Active and Novel Control Efficiency (FRANCE) is greatly acknowledged.

  2. Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma.

    Science.gov (United States)

    Liang, Wenjun; Li, Jian; Li, Jie; Jin, Yuquan

    2009-10-30

    Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO3 reactor had the highest toluene removal efficiency among the reactors. For NaNO2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

  3. Abatement of toluene from gas streams via ferro-electric packed bed dielectric barrier discharge plasma

    International Nuclear Information System (INIS)

    Liang Wenjun; Li Jian; Li Jie; Jin Yuquan

    2009-01-01

    Destruction of gaseous toluene via ferro-electric packed bed dielectric barrier discharge plasma in a coaxial cylindrical reactor was carried out at atmospheric pressure and room temperature. The difference among three kinds of reactors was compared in terms of specific energy density (SED), energy yield (EY), toluene decomposition. In order to optimize the geometry of the reactor, the removal efficiency of toluene was compared for various inner electrode diameters. In addition, qualitative analysis on by-products and particular discussion on toluene abatement mechanisms were also presented. It has been found that ferro-electric packed bed DBD reactor could effectively decompose toluene. Toluene removal efficiency enhanced with increasing SED. With respect to toluene conversion, 1.62 mm electrode appeared to be superior to 1.06 mm electrodes. BaTiO 3 reactor had the highest toluene removal efficiency among the reactors. For NaNO 2 reactor, the highest EY could reach 17.0 mg/kWh to a certain extent.

  4. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  5. Measurements of electric charge and screening length of microparticles in a plasma sheath

    International Nuclear Information System (INIS)

    Nakamura, Y.; Ishihara, O.

    2009-01-01

    An experiment is described in which microparticles are levitated within a rf sheath above a conducting plate in argon plasma. The microparticles forming a two-dimensional crystal structure are considered to possess Debye screening Coulomb potential φ(r)=(Q/4πε 0 r)exp(-r/λ), where Q is the electric charge, r is distance, and λ is the screening length. When the crystal structure is slanted with an angle θ, a particle experiences a force Mg sin θ, where M is the mass of the particle and g is acceleration due to gravity, which must be equal to the Debye screened Coulomb force from other particles. By changing θ, relations for λ(Q) are measured. The screening length λ and Q are determined uniquely from the crossing points of several relations. The electric charge Q is also estimated from a floating potential measured with a probe. The measured λ is nearly equal to an ion Debye length.

  6. The electrical asymmetry effect in geometrically asymmetric capacitive radio frequency plasmas

    International Nuclear Information System (INIS)

    Schüngel, E.; Schulze, J.; Czarnetzki, U.; Eremin, D.; Mussenbrock, T.

    2012-01-01

    The electrical asymmetry effect (EAE) allows an almost ideal separate control of the mean ion energy, i >, and flux, Γ i , at the electrodes in capacitive radio frequency discharges with identical electrode areas driven at two consecutive harmonics with adjustable phase shift, θ. In such geometrically symmetric discharges, a DC self bias is generated as a function of θ. Consequently, i > can be controlled separately from Γ i by adjusting the phase shift. Here, we systematically study the EAE in low pressure dual-frequency discharges with different electrode areas operated in argon at 13.56 MHz and 27.12 MHz by experiments, kinetic simulations, and analytical modeling. We find that the functional dependence of the DC self bias on θ is similar, but its absolute value is strongly affected by the electrode area ratio. Consequently, the ion energy distributions change and i > can be controlled by adjusting θ, but its control range is different at both electrodes and determined by the area ratio. Under distinct conditions, the geometric asymmetry can be compensated electrically. In contrast to geometrically symmetric discharges, we find the ratio of the maximum sheath voltages to remain constant as a function of θ at low pressures and Γ i to depend on θ at the smaller electrode. These observations are understood by the model. Finally, we study the self-excitation of non-linear plasma series resonance oscillations and its effect on the electron heating.

  7. Experiments and Computational Theory for Electrical Breakdown in Critical Components: THz Imaging of Electronic Plasmas.

    Energy Technology Data Exchange (ETDEWEB)

    Zutavern, Fred J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hjalmarson, Harold P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bigman, Verle Howard [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallegos, Richard Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    This report describes the development of ultra-short pulse laser (USPL) induced terahertz (THz) radiation to image electronic plasmas during electrical breakdown. The technique uses three pulses from two USPLs to (1) trigger the breakdown, (2) create a 2 picosecond (ps, 10 -12 s), THz pulse to illuminate the breakdown, and (3) record the THz image of the breakdown. During this three year internal research program, sub-picosecond jitter timing for the lasers, THz generation, high bandwidth (BW) diagnostics, and THz image acquisition was demonstrated. High intensity THz radiation was optically-induced in a pulse-charged gallium arsenide photoconductive switch. The radiation was collected, transported, concentrated, and co-propagated through an electro-optic crystal with an 800 nm USPL pulse whose polarization was rotated due to the spatially varying electric field of the THz image. The polarization modulated USPL pulse was then passed through a polarizer and the resulting spatially varying intensity was detected in a high resolution digital camera. Single shot images had a signal to noise of %7E3:1. Signal to noise was improved to %7E30:1 with several experimental techniques and by averaging the THz images from %7E4000 laser pulses internally and externally with the camera and the acquisition system (40 pulses per readout). THz shadows of metallic films and objects were also recorded with this system to demonstrate free-carrier absorption of the THz radiation and improve image contrast and resolution. These 2 ps THz pulses were created and resolved with 100 femtosecond (fs, 10 -15 s) long USPL pulses. Thus this technology has the capability to time-resolve extremely fast repetitive or single shot phenomena, such as those that occur during the initiation of electrical breakdown. The goal of imaging electrical breakdown was not reached during this three year project. However, plans to achieve this goal as part of a follow-on project are described in this document

  8. Two-dimensional spatial survey of the plasma potential and electric field in a pulsed bipolar magnetron discharge

    International Nuclear Information System (INIS)

    Vetushka, A.; Karkari, S.K.; Bradley, J.W.

    2004-01-01

    Emissive and Langmuir probe techniques have been used to obtain two-dimensional (2D) spatial maps of the plasma potential V p , electric field E, and ion trajectories in a pulsed bipolar magnetron discharge. The magnetron was pulsed at a frequency of 100 kHz, with a 50% duty cycle and operated at an argon pressure of 0.74 Pa. The pulse wave form was characterized by three distinct phases: the 'overshoot', 'reverse', and 'on' phases. In the 'on' phase of the pulse, when the cathode voltage is driven to -670 V, the 2D spatial distribution of V p has a similar form to that in dc magnetron, with significant axial and radial electric fields in the bulk plasma, accelerating ions to the sheath edge above the cathode racetrack region. During the 'overshoot' phase (duration 200 ns), V p is raised to values greater than +330 V, more than 100 V above the cathode potential, with E pointing away from the target. In the 'reverse' phase V p has a value of +45 V at all measured positions, 2 V more positive than the target potential. In this phase there is no electric field present in the plasma. In the bulk of the plasma, the results from Langmuir probe and the emissive probe are in good agreement, however, in one particular region of the plasma outside the radius of the cathode, the emissive probe measurements are consistently more positive (up to 45 V in the 'on' time). This discrepancy is discussed in terms of the different frequency response of the probes and their perturbation of the plasma. A simple circuit model of the plasma-probe system has been proposed to explain our results. A brief discussion of the effect of the changing plasma potential distribution on the operation of the magnetron is given

  9. The effect of an alternating electric field on a totally ionised plasma; Action d'un champ electrique alternatif sur un plasma totalement ionise

    Energy Technology Data Exchange (ETDEWEB)

    Baglin, H; Brin, A; Ozias, Y; Salmon, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Delcroix, J L [Ecole Normale Superieure, 75 - Paris (France)

    1960-07-01

    The equation giving the distribution function of the electrons in a steady-state, for a fully ionized plasma in an a.c. field, are provided from the Fokker-Planck equation. The electric conductivity is complex and depends on the frequency. (author) [French] L'equation qui donne la fonction de distribution des electrons dans un etat stationnaire pour un plasma totalement ionise dans un champ electrique alternatif est fournie par l'equation de Fokker-Planck. La conductibilite electrique est complexe et depend de la frequence. (auteur)

  10. The influence of γ-irradiation cobalt 60 on electrical properties of undoped GaAs treated with hydrogen plasma

    International Nuclear Information System (INIS)

    Korshunov, F.P.; Kurilovich, N.F.; Prokhorenko, T.A.; Bumaj, Yu.A.; Ul'yashin, A.G.

    1999-01-01

    The influence of exposition to a hydrogen plasma (hydrogenation) on the electrical properties alteration under gamma-irradiation in bulk GaAs have been investigated. It is shown that crystals hydrogenation before irradiation leads to particularly passivation of electrically active defects that are responsible for carriers scattering and removing processes in irradiated crystals. Radiation defects thermostability in hydrogenated GaAs crystals is lower than that in non hydrogenated ones. The energetic levels position of main defect that effects on electrical properties alteration after irradiation in GaAs crystals was detected. It is equal to E D =E C -0,125±0,0005 eV

  11. Electronic load as part of the test complex of the power processing unit of electric and plasma propulsion

    OpenAIRE

    Chubov, S. V.; Soldatov, Aleksey Ivanovich

    2017-01-01

    This article provides the advantages and technical solutions for the use of electronic loads as part of a testing complex of power and management systems of electric and plasma propulsion of three types. The paper shows the parameters that were applied to select the electronic loads and describes their functionality.

  12. Asymptotic behavior of correlation functions for electric potential and field fluctuations in a classical one-component plasma

    NARCIS (Netherlands)

    Suttorp, L.G.

    1992-01-01

    The correlations of the electric potential fluctuations in a classical one-component plasma are studied for large distances between the observation points. The two-point correlation function for these fluctuations is known to decay slowly for large distances, even if exponential clustering holds for

  13. Structural and electrical manifestation of aging in thin-film Fe-Ta-O nanocomposite prepared by plasma jet technique

    Czech Academy of Sciences Publication Activity Database

    Lobotka, P.; Vávra, I.; Fendrych, František; Chayka, Oleksandr

    2004-01-01

    Roč. 201, č. 7 (2004), s. 1493-1499 ISSN 0031-8965 R&D Projects: GA AV ČR KSK1010104 Keywords : nanocomposite fils Fe-Ta-O * plasma jet * tunneling * electrical transport * magnetoresistance * ageing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.860, year: 2004

  14. Study of the properties of the operation of an end-type plasma accelerator initiated by electric foil detonation

    International Nuclear Information System (INIS)

    Gol'dberg, M.M.; Vikaruk, A.Ya.; Sokolov, S.V.; Suminov, I.V.

    1986-01-01

    The results of experimental study of an end-type high-current pulsed plasma accelerator initiated by electric foil detonation are presented. The development stages of the process and formation of the flow pinch are examined during accelerator operation. Analytic functions are obtained which determine the origination conditions of the pinch-effect

  15. Self-Generated Magnetic Fields in Stagnation-Phase ICF Implosions

    Science.gov (United States)

    Walsh, Christopher; Chittenden, Jeremy; McGlinchey, Kristopher; Niasse, Nicolas

    2016-10-01

    3-D extended-MHD simulations of the stagnation phase of an ICF implosion are presented, showing significant self-generated magnetic fields (1000-5000T) due to the Biermann Battery effect. Perturbed hot-spots generate magnetic fields at their edges, as the extremities of hot bubbles are rapidly cooled by the surrounding low temperature fuel, giving non-parallel electron pressure and density gradients. Larger amplitude and higher mode-number perturbations lead to an increased hot-spot surface area and more heat flow, developing greater non-parallel gradients and therefore larger magnetic fields. Due to this, largely perturbed hot-spots can be affected more by magnetic fields, although the accelerated cooling associated with greater deviations from symmetry lowers magnetisation. The Nernst effect advects magnetic field down temperature gradients towards the outer region of the hot-spot, which can also lower the magnetisation of the plasma. In some regions, however, the Nernst velocity is convergent, magnetising the tips of cold fuel spikes, resulting in anisotropic heat-flow and an improvement in energy containment. Low-mode and multi-high-mode simulations are shown, with magnetisations reaching sufficiently high levels in some regions of the hot-spot to suppress thermal conduction to lower than 50% of the unmagnetised case. A quantitative analysis of how this affects the hot-spot energy balance is included.

  16. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma.

    Directory of Open Access Journals (Sweden)

    Andrew L Frelinger

    Full Text Available Activated autologous platelet-rich plasma (PRP used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma.To determine whether sub-microsecond duration, low electric field (SMLEF bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity.PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF, vascular endothelial growth factor (VEGF, endothelial growth factor (EGF and platelet factor 4 (PF4, and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin.PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the presence of platelet

  17. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma.

    Science.gov (United States)

    Frelinger, Andrew L; Gerrits, Anja J; Garner, Allen L; Torres, Andrew S; Caiafa, Antonio; Morton, Christine A; Berny-Lang, Michelle A; Carmichael, Sabrina L; Neculaes, V Bogdan; Michelson, Alan D

    2016-01-01

    Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma. To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity. PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin. PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the presence of platelet

  18. [The electric furnace of Henri Moissan at one hundred years: connection with the electric furnace, the solar furnace, the plasma furnace?].

    Science.gov (United States)

    Royère, C

    1999-03-01

    The trace of Henri Moissan's pioneer work 100 years ago is clearly evidenced by an overview of achievements in high temperature devices; 1987: "Le four électrique" by Henri Moissan; 1948-1952: "High temperature heating in a cavity rotary kiln using focusing of solar radiation" by Félix Trombe; 1962: "The cavity rotary kiln using focused solar radiation jointly with a plasma gun" by Marc Foëx; 1970: "The rotary kiln with two plasma guns and arc transfer" by Marc Foëx; 1984: "The plasma furnace" by Electricité de France (EDF) at Renardières; 1997: "The plasma furnace" by the Atomic Energy Center (CEA) at Cadarache, the VULCANO program. The first part of this contribution is devoted to Henri Moissan. Re-reading his early book on the electric furnace, especially the first chapter and the sections on silica, carbon vapor and experiments performed in casting molten metal--the conclusions are outstanding--provides modern readers with an amazing insight into future developments. The last two parts are devoted to Félix Trombe and Marc Foëx, tracing the evolution of high temperature cavity processus leading to the solar furnace and the present day plasma furnace at the CEA. Focus is placed on research conducted by the French National Center for Scientific Research (CNRS) with the solar and plasma furnaces at Odeillo. The relationships with Henri Moissan's early work are amazing, offering a well deserved homage to this pioneer researcher.

  19. Effect of voltage shape of electrical power supply on radiation and density of a cold atmospheric argon plasma jet

    Directory of Open Access Journals (Sweden)

    F Sohbatzadeh

    2017-02-01

    Full Text Available In this work, we investigated generating argon cold plasma jet at atmospheric pressure based on dielectric barrier discharge configuration using three electrical power supplies of sinusoidal, pulsed and saw tooth high voltage shapes at 8 KHZ. At first; we describe the electronic circuit features for generating high voltage (HV wave forms including saw tooth, sinusoidal and pulsed forms. Then, we consider the effect of voltage shape on the electrical breakdown. Relative concentrations of chemical reactive species such as Oxygen, atomic Nitrogen and OH were measured using optical emission spectroscopy. Using a simple numerical model, we showed a HV with less rise time increases electron density, therefore a cold plasma jet can be produced with a minimal consumption electrical power

  20. Simulations of momentum transfer process between solar wind plasma and bias voltage tethers of electric sail thruster

    Science.gov (United States)

    Xia, Guangqing; Han, Yajie; Chen, Liuwei; Wei, Yanming; Yu, Yang; Chen, Maolin

    2018-06-01

    The interaction between the solar wind plasma and the bias voltage of long tethers is the basic mechanism of the electric sail thruster. The momentum transfer process between the solar wind plasma and electric tethers was investigated using a 2D full particle PIC method. The coupled electric field distribution and deflected ion trajectory under different bias voltages were compared, and the influence of bias voltage on momentum transfer process was analyzed. The results show that the high potential of the bias voltage of long tethers will slow down, stagnate, reflect and deflect a large number of ions, so that ion cavities are formed in the vicinity of the tether, and the ions will transmit the axial momentum to the sail tethers to produce the thrust. Compared to the singe tether, double tethers show a better thrust performance.

  1. Physics-electrical hybrid model for real time impedance matching and remote plasma characterization in RF plasma sources.

    Science.gov (United States)

    Sudhir, Dass; Bandyopadhyay, M; Chakraborty, A

    2016-02-01

    Plasma characterization and impedance matching are an integral part of any radio frequency (RF) based plasma source. In long pulse operation, particularly in high power operation where plasma load may vary due to different reasons (e.g. pressure and power), online tuning of impedance matching circuit and remote plasma density estimation are very useful. In some cases, due to remote interfaces, radio activation and, due to maintenance issues, power probes are not allowed to be incorporated in the ion source design for plasma characterization. Therefore, for characterization and impedance matching, more remote schemes are envisaged. Two such schemes by the same authors are suggested in these regards, which are based on air core transformer model of inductive coupled plasma (ICP) [M. Bandyopadhyay et al., Nucl. Fusion 55, 033017 (2015); D. Sudhir et al., Rev. Sci. Instrum. 85, 013510 (2014)]. However, the influence of the RF field interaction with the plasma to determine its impedance, a physics code HELIC [D. Arnush, Phys. Plasmas 7, 3042 (2000)] is coupled with the transformer model. This model can be useful for both types of RF sources, i.e., ICP and helicon sources.

  2. Production of organic compounds in plasmas - A comparison among electric sparks, laser-induced plasmas, and UV light

    Science.gov (United States)

    Scattergood, Thomas W.; Mckay, Christopher P.; Borucki, William J.; Giver, Lawrence P.; Van Ghyseghem, Hilde

    1989-01-01

    In order to ascertain the features of organic compound-production in planetary atmospheres under the effects of plasmas and shocks, various mixtures of N2, CH4, and H2 modeling the atmosphere of Titan were subjected to discrete sparks, laser-induced plasmas, and UV radiation. The experimental results obtained suggest that UV photolysis from the plasma is an important organic compound synthesis process, as confirmed by the photolysis of gas samples that were exposed to the light but not to the shock waves emitted by the sparks. The thermodynamic equilibrium theory is therefore incomplete in the absence of photolysis.

  3. Surface Electrical Potentials of Root Cell Plasma Membranes: Implications for Ion Interactions, Rhizotoxicity, and Uptake

    Directory of Open Access Journals (Sweden)

    Yi-Min Wang

    2014-12-01

    Full Text Available Many crop plants are exposed to heavy metals and other metals that may intoxicate the crop plants themselves or consumers of the plants. The rhizotoxicity of heavy metals is influenced strongly by the root cell plasma membrane (PM surface’s electrical potential (ψ0. The usually negative ψ0 is created by negatively charged constituents of the PM. Cations in the rooting medium are attracted to the PM surface and anions are repelled. Addition of ameliorating cations (e.g., Ca2+ and Mg2+ to the rooting medium reduces the effectiveness of cationic toxicants (e.g., Cu2+ and Pb2+ and increases the effectiveness of anionic toxicants (e.g., SeO42− and H2AsO4−. Root growth responses to ions are better correlated with ion activities at PM surfaces ({IZ}0 than with activities in the bulk-phase medium ({IZ}b (IZ denotes an ion with charge Z. Therefore, electrostatic effects play a role in heavy metal toxicity that may exceed the role of site-specific competition between toxicants and ameliorants. Furthermore, ψ0 controls the transport of ions across the PM by influencing both {IZ}0 and the electrical potential difference across the PM from the outer surface to the inner surface (Em,surf. Em,surf is a component of the driving force for ion fluxes across the PM and controls ion-channel voltage gating. Incorporation of {IZ}0 and Em,surf into quantitative models for root metal toxicity and uptake improves risk assessments of toxic metals in the environment. These risk assessments will improve further with future research on the application of electrostatic theory to heavy metal phytotoxicity in natural soils and aquatic environments.

  4. Modification of the turbulence in the plasma boundary of the Wendelstein 7-AS stellarator using electric probes

    International Nuclear Information System (INIS)

    Thomsen, H.; Endler, M.; Schubert, M.

    2001-01-01

    The fluctuations in the edge plasmas of magnetic fusion experiments are thought to play an important role in terms of anomalous energy and particle transport. Experiments on Wendelstein 7-AS were conducted with the primary goal to investigate the performance of influencing and modifying the turbulence in the plasma boundary using electrical probes. Two movable poloidal probe arrays were used for the experiments, one located on the inboard side of the vessel and the other on the outboard side. A subset of probe tips was used for actively driving the plasma by different control signals, the remaining probes collected fluctuation data in the plasma boundary. Poloidally, we find a significant cross-correlation between active and passive probes. From analysis of the coherency and phases of the passive probe tips, it can clearly be seen that the background ExB-rotation of the plasma plays a crucial role for the applied signals. In the case of externally driven waves by several phase-locked active probes, the direction of the wave propagation with respect to the plasma rotation (co- or counter-rotating) is essential for a proper coupling to the turbulence. In toroidal direction we find that the propagation of the signals along the magnetic field lines depends on co- or counter-rotation with respect to the background plasma rotation. (author)

  5. Effects of annealing and plasma treatment on the electrical and optical properties of spin-coated ITZO films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong-min; Kim, Jae-Kwan [Department of Materials Science and Metallurgical Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of); Hao, Jinchen; Kim, Han-Ki [Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Yoon, Jae-Sik [Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333 (Korea, Republic of); Lee, Ji-Myon, E-mail: jimlee@sunchon.ac.kr [Department of Printed Electronics Engineering, Sunchon National University, Sunchon, Chonnam 540-742 (Korea, Republic of)

    2014-01-15

    Highlights: • The resistivity of ITZO was enhanced by H{sub 2} gas plasma treatment. • The transmittance of H{sub 2} treated film was same as that of ref. after wet treatment. • The plasma process was carried out at room temperature. -- Abstract: This paper reports the effects on the optical and electrical properties of indium tin zinc oxide (ITZO) films by annealing and hydrogen plasma treatment. ITZO films were prepared by spin-coating using ITZO nanoink. The sheet resistance of the spin-coated ITZO was decreased to 155 Ω/square after annealing at 300 °C. Subsequent inductively-coupled hydrogen plasma decreased the sheet resistance of the ITZO film further to 88 Ω/square due to the formation of a high density of O–H bonds and oxygen vacancies leaving a metal cluster on the surface, which is comparable to that of solution-processed ITO films. Although the transmittance of the hydrogen plasma-treated sample was decreased considerable by the formation of metal clusters, the transmittance and optical band gap could be enhanced without a deteriorating the electrical properties by removing the metal clusters using a H{sub 2}SO{sub 4} solution.

  6. Modulation of electrical properties in Cu/n-type InP Schottky junctions using oxygen plasma treatment

    International Nuclear Information System (INIS)

    Kim, Hogyoung; Jung, Chan Yeong; Hyun Kim, Se; Cho, Yunae; Kim, Dong-Wook

    2015-01-01

    Using current–voltage (I–V) measurements, we investigated the effect of oxygen plasma treatment on the temperature-dependent electrical properties of Cu/n-type indium phosphide (InP) Schottky contacts at temperatures in the range 100–300 K. Changes in the electrical parameters were evident below 180 K for the low-plasma-power sample (100 W), which is indicative of the presence of a wider distribution of regions of low barrier height. Modified Richardson plots were used to obtain Richardson constants, which were similar to the theoretical value of 9.4 A cm −2 K −2 for n-type InP. This suggests that, for all the samples, a thermionic emission model including a spatially inhomogeneous Schottky barrier can be used to describe the charge transport phenomena at the metal/semiconductor interface. The voltage dependence of the reverse-bias current revealed that Schottky emission was dominant for the untreated and high-plasma-power (250 W) samples. For the low-plasma-power sample, Poole–Frenkel emission was dominant at low voltages, whereas Schottky emission dominated at higher voltages. Defect states and nonuniformity of the interfacial layer appear to be significant in the reverse-bias charge transport properties of the low-plasma-power sample. (paper)

  7. Effect of calcination environments and plasma treatment on structural, optical and electrical properties of FTO transparent thin films

    Directory of Open Access Journals (Sweden)

    Madhav Kafle

    2017-07-01

    Full Text Available The dependence of the structural, optical and electrical properties of the FTO thin films on the film thickness (276 nm - 546 nm, calcination environment, and low temperature plasma treatment were examined. The FTO thin films, prepared by spray pyrolysis, were calcinated under air followed by either further heat treatment under N2 gas or treatment in low temperature atmospheric plasma. The samples before and after calcination under N2, and plasma treatment will be represented by Sair, SN2 and SPl, respectively, hereafter. The thin films were characterized by measuring the XRD spectra, SEM images, optical transmittance and reflectance, and sheet resistance of the films before and after calcination in N2 environment or plasma treatment. The presence of sharp and narrow multiple peaks in XRD spectra hint us that the films were highly crystalline (polycrystalline. The samples Sair with the thickness of 471 nm showed as high as 92 % transmittance in the visible range. Moreover, from the tauc plot, the optical bandgap Eg values of the Sair found to be noticeably lower than that of the samples SN2. Very surprisingly, the electrical sheet resistance (Rsh found to decrease following the trend as Rshair > RshN2 > RshPl. The samples exposed to plasma found to possess the lowest RshPl (for film with thickness 546 nm, the RshPl was 17 Ω/sq..

  8. Production of organic compounds in plasmas: A comparison among electric sparks, laser-induced plasmas and UV light

    Science.gov (United States)

    Scattergood, T. W.; Mckay, C. P.; Borucki, W. J.; Giver, L. P.; Vanghyseghem, H.; Parris, J. E.; Miller, S. L.

    1991-01-01

    In order to study the production of organic compounds in plasmas (and shocks), various mixtures of N2, CH4, and H2, modeling the atmosphere of Titan, were exposed to discrete sparks, laser-induced plasmas (LIP) and ultraviolet light. The yields of HCN and simple hydrocarbons were measured and compared to those calculated from a simple quenched thermodynamic equilibrium model. The agreement between experiment and theory was fair for HCN and C2H2. However, the yields of C2H6 and other hydrocarbons were much higher than those predicted by the model. Our experiments suggest that photolysis by ultraviolet light from the plasma is an important process in the synthesis. This was confirmed by the photolysis of gas samples exposed to the light, but not to the plasma or shock waves. The results of these experiments demonstrate that, in addition to the well-known efficient synthesis of organic compounds in plasmas, the yields of saturated species, e.g., ethane, may be higher than predicted by theory and that LIP provide a convenient and clean way of simulating planetary lightning and impact plasmas in the laboratory.

  9. Temporal and spatial spectroscopy of the plasma formation in crossed electric and magnetic fields

    International Nuclear Information System (INIS)

    Miljevic, V.I.; Tosic, D.D.

    1980-01-01

    The formation of argon plasma in crossed electric and magnetic fields in a cylindrical diode with an incandescent cathode has been studied by means of the delay time of the anode current pulse and photon pulse (corresponding to the optical transitions) and the shape of the voltage collapse. The working conditions were: pressure p=10 -5 --10 -3 Torr, anode voltage U/sub a/=800 V, and maximum magnetic field B/sub max/=1200 Gs. Photoelectrical recording of spectral lines was performed with a monochromator in the wavelength range 3600--6000 A, and the total optical spectrum was recorded simultaneously on a photoplate in a separate spectrograph in the wavelength range 2000--10 000 A. The delay time of the anode current pulse and photon pulse are approximately the same and are in the millisecond range. The delay time of the photon pulse does not depend on the wavelength. Simultaneously the spectral lines of the working gas (A II), residual gas (O II), and tungsten (W I) appear. Tungsten atoms appear at the moment of breakdown as a result of ion bombardment of the cathode. Neutral atomic lines of the working gas (A I) have not been observed. Radial analysis shows that the delay time of the photon pulse does not depend on the radius. Spectroscopic results have been analyzed in terms of excitation and ionization processes during the formation time. The shape of the voltage collapse suggests the streamer breakdown mechanism

  10. Electrical and optical characteristics of the radio frequency surface dielectric barrier discharge plasma actuation

    International Nuclear Information System (INIS)

    Wang Wei-Long; Song Hui-Min; Li Jun; Jia Min; Wu Yun; Jin Di

    2016-01-01

    Electrical characteristics and optical emission spectrum of the radio frequency (RF) surface dielectric barrier discharge (SDBD) plasma actuation are investigated experimentally in this paper. Influences of operating pressure, duty cycle and load power on the discharge are analyzed. When the operating pressure reaches 30 kPa, the discharge energy calculated from the Charge–Voltage (Q–V) Lissajous figure increases significantly, while the effective capacitance decreases remarkably. As the duty cycle of the applied voltage increases, the voltage–current waveforms, the area of Q–V loop and the capacity show no distinct changes. Below 40 W, effective capacitance increases with the increase of load power, but it almost remains unchanged when load power is between 40 W and 95 W. The relative intensity changes little as the operating pressure varies from 4 kPa to 100 kPa, while it rises evidently with the pressure below 4 kPa, which indicates that the RF discharge mode shifts from filamentary discharge to glow discharge at around 4 kPa. With the increase of load power, the relative intensity rises evidently. Additionally, the relative intensity is insensitive to the pressure, the duty cycle, and the load power. (paper)

  11. Effects of phosphorus on the electrical characteristics of plasma deposited hydrogenated amorphous silicon carbide thin films

    Science.gov (United States)

    Alcinkaya, Burak; Sel, Kivanc

    2018-01-01

    The properties of phosphorus doped hydrogenated amorphous silicon carbide (a-SiCx:H) thin films, that were deposited by plasma enhanced chemical vapor deposition technique with four different carbon contents (x), were analyzed and compared with those of the intrinsic a-SiCx:H thin films. The carbon contents of the films were determined by X-ray photoelectron spectroscopy. The thickness and optical energies, such as Tauc, E04 and Urbach energies, of the thin films were determined by UV-Visible transmittance spectroscopy. The electrical properties of the films, such as conductivities and activation energies were analyzed by temperature dependent current-voltage measurements. Finally, the conduction mechanisms of the films were investigated by numerical analysis, in which the standard transport mechanism in the extended states and the nearest neighbor hopping mechanism in the band tail states were taken into consideration. It was determined that, by the effect of phosphorus doping the dominant conduction mechanism was the standard transport mechanism for all carbon contents.

  12. Numerical simulation for arc-plasma dynamics during contact opening process in electrical circuit-breakers

    International Nuclear Information System (INIS)

    Gupta, D N; Srinivas, D; Patil, G N; Kale, S S; Potnis, S B

    2010-01-01

    The high-energy, high-current thermal plasma that develops between electric contacts in a gas circuit-breaker during circuit interruption is an important phenomenon in the power transmission industry. The high temperature and pressure arc dissipates the tremendous amount of energy generated by the fault current. Simultaneously, this energy has to be transferred away from the contacts to build the dielectric strength level of the circuit-breaker. In order to interrupt the current, the arc must be weakened and finally extinguished. We model these phenomena by using a computer software code based on the solution of the unsteady Euler equations of gas dynamics. We consider the equations of fluid flows. These equations are solved numerically in complex circuit breaker geometries using a finite-volume method. The domain is initially filled with SF 6 gas. We begin our simulations from cold mode, where the fault current is not present (hence no arc). An axis-symmetric geometry of a 145 kV gas circuit-breaker is considered to study the pressure, density, and temperature profile during contact opening process.

  13. Induced charge of spherical dust particle on plasma-facing wall in non-uniform electric field

    International Nuclear Information System (INIS)

    Tomita, Y.; Smirnov, R.; Zhu, S.

    2005-01-01

    Induced charge of a spherical dust particle on a plasma-facing wall is investigated analytically, where non-uniform electric field is applied externally. The one-dimensional non-uniform electrostatic potential is approximated by the polynomial of the normal coordinate toward the wall. The bipolar coordinate is introduced to solve the Laplace equation of the induced electrostatic potential. The boundary condition at the dust surface determines the unknown coefficients of the general solution of the Laplace equation for the induced potential. From the obtained potential the surface induced charge can be calculated. This result allows estimating the effect of the surrounding plasma, which shields the induced charge. (author)

  14. Radially and temporally resolved electric field of positive streamers in air and modelling of the induced plasma chemistry

    Czech Academy of Sciences Publication Activity Database

    Hoder, T.; Šimek, Milan; Bonaventura, Z.; Prukner, Václav; Gordillo-Vázquez, F.J.

    2016-01-01

    Roč. 25, č. 4 (2016), č. článku 045021. ISSN 0963-0252 R&D Projects: GA ČR(CZ) GA15-04023S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431201 Program:M Institutional support: RVO:61389021 Keywords : streamer * electric field * Blue Jet * air plasma chemistry * transient luminous event Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.302, year: 2016 http://iopscience.iop.org/article/10.1088/0963-0252/25/4/045021/meta

  15. Theoretical study of structure of electric field in helical toroidal plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.

    2001-06-01

    A set of transport equations is analyzed, including the bifurcation of the electric field. The structure of the electric field is studied by use of the theoretical model for the anomalous transport diffusivities. The steep gradient of the electric field is obtained at the electric domain. The suppression of the anomalous transport diffusivity is studied in the presence of the strong shear of the electric field. The hard transition with the multiple ambipolar solutions is examined in the structure of the radial electric field. The details of the structure of the electric domain interface are investigated. (author)

  16. Observation of enhanced electric field in an RF-plugged sheet plasma in the RFC-XX-M open-ended machine

    International Nuclear Information System (INIS)

    Oda, T.; Takiyama, K.; Kadota, K.

    1987-12-01

    We report nonperturbing observation of the electric field in the sheet plasma for RF end-plugging on the RFC XX-M open-ended machine by using the Stark effect with a combined technique of beam-probe and laser-induced fluorescence. Under the optimum condition for the RF plugging, enhanced electric field is found in the sheet plasma by about 2.5 times with respect to the electric field when no plasma is produced. The field spatial profile is also measured, which is discussed in connection with the electrostatic eigenmode. (author)

  17. Dynamics of self-generated magnetic fields in stagnation phase and their effects on hot spark formation

    International Nuclear Information System (INIS)

    Hata, Akiro; Mima, Kunioki; Nagatomo, Hideo; Sunahara, Atsushi; Nishiguchi, Akio

    2006-01-01

    The generalized temporal evolution equation of a magnetic field is derived for high density laser-fusion plasmas. Magnetic field generation and convection are simulated by using the 2D hydrodynamic code together with the magnetic field equation. It is found that magnetic fields are generated and compressed in association with the Rayleigh-Taylor instability of an imploding shell. In particular, the magnetic field convection by the Nernst effect is found to play an important role in the amplification of magnetic fields. The maximum magnetic field reaches 30 MG at maximum compression. This magnetic field may reduce the electron heat conduction around the hot spark. Therefore, it is concluded that the ignition condition for non-uniform implosion is influenced by self-generated magnetic fields. (author)

  18. Organic compound destruction and removal efficiency (DRE) for plasma incinerator off-gases using an electrically heated secondary combustion chamber

    International Nuclear Information System (INIS)

    Whitworth, C.G.; Babko-Malyi, S.; Battleson, D.M.; Olstad, S.J.

    1998-01-01

    The US Department of Energy (DOE) sponsored a series pilot-scale plasma incineration tests of simulated mixed wastes at the MSE Technology Applications, Inc. technology development test facility in Butte, MT. One of the objectives of the test series was to assess the ability of an electrically heated afterburner to destroy organic compounds that may be present in the off-gases resulting from plasma incineration of mixed wastes. The anticipated benefit of an electrically heated afterburner was to decrease total off-gas volume by 50% or more, relative to fossil fuel-fired afterburners. For the present test series, feeds of interest to the DOE Mixed Waste Focus Area (MWFA) were processed in a plasma centrifugal furnace while metering selected organic compounds upstream of the electrically heated afterburner. The plasma furnace was equipped with a transferred-mode torch and was operated under oxidizing conditions. Feeds consisted of various mixtures of soil, plastics, portland cement, silicate fines, diesel fuel, and scrap metals. Benzene, chloroform, and 1,1,1-trichloroethane were selected for injection as simulates of organics likely to be present in DOE mixed wastes, and because of their relative rankings on the US Environmental Protection Agency (EPA) thermal stability index. The organic compounds were injected into the off-gas system at a nominal concentration of 2,000 ppmv. The afterburner outlet gas stream was periodically sampled, and analyzed by gas chromatography/mass spectrometry. For the electrically heated afterburner, at operating temperatures of 1,800--1,980 F (982--1,082 C), organic compound destruction and removal efficiencies (DREs) for benzene, chloroform, and 1,1,1-trichloroethane were found to be > 99.99%

  19. Role of turbulence and electric fields in the establishment of improved confinement in tokamak plasmas

    Czech Academy of Sciences Publication Activity Database

    Van Oost, G.; Bulanin, V.V.; Donné, A.J.H.; Gusakov, E.Z.; Krämer-Flecken, A.; Krupnik, L.I.; Melnikov, A.; Peleman, P.; Razumova, K.; Stöckel, Jan; Vershkov, V.; Altukov, A.B.; Andreev, V.F.; Askinazi, L.G.; Bondarenko, I.S.; Dnestrovskij, A.Yu.; Eliseev, L.G.; Esipov, L.A.; Grashin, S.A.; Gurchenko, A.D.; Hogeweij, G.M.D.; Jachmin, S.; Khrebtov, S.M.; Kouprienko, D.V.; Lysenko, S.E.; Perfilov, S.V.; Petrov, A.V.; Popov, A.Yu.; Reiser, D.; Soldatov, S.; Stepanov, A.Yu.; Telesca, G.; Urazbaev, A.O.; Verdoolaege, G.; Zimmermann, O.

    2006-01-01

    Roč. 12, č. 6 (2006), s. 14-19 ISSN 1562-6016. [International Conference on Plasma Physics and Technology/11th./. Alushta, 11.9.2006-16.9.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * plasma * improved confinement * turbulence Subject RIV: BL - Plasma and Gas Discharge Physics http:// vant .kipt.kharkov.ua/TABFRAME.html

  20. The TELEC - A plasma type of direct energy converter. [Thermo-Electronic Laser Energy Converter for electric power generation

    Science.gov (United States)

    Britt, E. J.

    1978-01-01

    The Thermo-Electronic Laser Energy Converter (TELEC) is a high-power density plasma device designed to convert a 10.6-micron CO2 laser beam into electric power. Electromagnetic radiation is absorbed in plasma electrons, creating a high-electron temperature. Energetic electrons diffuse from the plasma and strike two electrodes having different areas. The larger electrode collects more electrons and there is a net transport of current. An electromagnetic field is generated in the external circuit. A computer program has been designed to analyze TELEC performance allowing parametric variation for optimization. Values are presented for TELEC performance as a function of cesium pressure and for current density and efficiency as a function of output voltage. Efficiency is shown to increase with pressure, reaching a maximum over 45%.

  1. Higher Order Analysis of Turbulent Changes Found in the ELF Range Electric Field Plasma Before Major Earthquakes

    Science.gov (United States)

    Kosciesza, M.; Blecki, J. S.; Parrot, M.

    2014-12-01

    We report the structure function analysis of changes found in electric field in the ELF range plasma turbulence registered in the ionosphere over epicenter region of major earthquakes with depth less than 40 km that took place during 6.5 years of the scientific mission of the DEMETER satellite. We compare the data for the earthquakes for which we found turbulence with events without any turbulent changes. The structure functions were calculated also for the Polar CUSP region and equatorial spread F region. Basic studies of the turbulent processes were conducted with use of higher order spectra and higher order statistics. The structure function analysis was performed to locate and check if there are intermittent behaviors in the ionospheres plasma over epicenter region of the earthquakes. These registrations are correlated with the plasma parameters measured onboard DEMETER satellite and with geomagnetic indices.

  2. Modification of optical and electrical properties of chemical bath deposited SnS using O{sub 2} plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Gómez, A. [Facultad de Ciencias, Universidad Autónoma del Estado de México, Estado de México, México (Mexico); Martínez, H., E-mail: hm@fis.unam.mx [Instituto de Ciencias Fisicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62251, Cuernavaca, Morelos (Mexico); Calixto-Rodríguez, M. [Centro de Investigación en Energía, Universidad Autónoma del Estado de México, Estado de México, México (Mexico); Avellaneda, D. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, México (Mexico); Reyes, P.G. [Facultad de Ciencias, Universidad Autónoma del Estado de México, Estado de México, México (Mexico); Flores, O. [Instituto de Ciencias Fisicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, 62251, Cuernavaca, Morelos (Mexico)

    2013-06-15

    In this paper, we report modifications of structural and optical, electrical properties that occur in tin sulphide (SnS) treated in O{sub 2} plasma. The SnS thin films were deposited by chemical bath deposition technique. The samples were treated in an O{sub 2} plasma discharge at 3 Torr of pressure discharge, a discharge voltage of 2.5 kV and 20 mA of discharge current. The prepared and treated thin films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The photoconductivity and electrical effects of SnS have been studied. The SnS thin films had an orthorhombic crystalline structure. With the plasma treatment the optical gap and electrical properties of the SnS films changed from 1.61 to 1.84 eV, for 3.9 × 10{sup 5} to 10.42 Ω cm, respectively. These changes can be attributed to an increase in electron density, percolation effects due to porosity, surface degradation/etching that is an increase in surface roughness, where some structural changes related to crystallinity occurs like a high grain size as revealed by SEM images.

  3. System analysis and test-bed for an atmosphere-breathing electric propulsion system using an inductive plasma thruster

    Science.gov (United States)

    Romano, F.; Massuti-Ballester, B.; Binder, T.; Herdrich, G.; Fasoulas, S.; Schönherr, T.

    2018-06-01

    Challenging space mission scenarios include those in low altitude orbits, where the atmosphere creates significant drag to the S/C and forces their orbit to an early decay. For drag compensation, propulsion systems are needed, requiring propellant to be carried on-board. An atmosphere-breathing electric propulsion system (ABEP) ingests the residual atmosphere particles through an intake and uses them as propellant for an electric thruster. Theoretically applicable to any planet with atmosphere, the system might allow to orbit for unlimited time without carrying propellant. A new range of altitudes for continuous operation would become accessible, enabling new scientific missions while reducing costs. Preliminary studies have shown that the collectible propellant flow for an ion thruster (in LEO) might not be enough, and that electrode erosion due to aggressive gases, such as atomic oxygen, will limit the thruster lifetime. In this paper an inductive plasma thruster (IPT) is considered for the ABEP system. The starting point is a small scale inductively heated plasma generator IPG6-S. These devices are electrodeless and have already shown high electric-to-thermal coupling efficiencies using O2 and CO2 . The system analysis is integrated with IPG6-S tests to assess mean mass-specific energies of the plasma plume and estimate exhaust velocities.

  4. Dependence of plasma treatment of ITO electrode films on electrical and optical properties of polymer light-emitting diodes

    International Nuclear Information System (INIS)

    Kim, Seung Ho; Baek, Seung Jun; Chang, Ho Jung; Chang, Young Chul

    2012-01-01

    Polymer light-emitting diodes (PLEDs) having indium tin oxide (ITO)/PEDOT:PSS [poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate]/PVK [poly-vinylcarbazole]:PFO-poss [poly(9,9-dioctylfluorene) end capped by polyhedral oligomeric silsesquioxane]/TPBI [2,2',2''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)]/LiF/Al structures were prepared on plasma-treated ITO/glass substrates using spin-coating and thermal evaporation methods. The effects of the plasma treatment on the ITO films to the optical and electrical properties of the PLEDs were examined. The sheet resistance of the ITO films decreased with an increasing radio frequency (RF) plasma intensity from 20 to 200 W under a 20 mTorr Ar + O 2 gas (50:50 vol.%) pressure. The work function of the ITO films without plasma treatment was 4.97 eV, and increased to about 5.16-5.23 eV after the plasma treatment of the films. The surface roughness improved with increasing plasma intensities. The luminance and current efficiency of the PLEDs were improved when the devices were prepared on the plasma-treated ITO/glass substrates. The maximum current density and luminance for the PLEDs was obtained at a 150-W RF plasma intensity; they were 310 mA cm -2 and 2535 cd m -2 at 9 V, respectively. The Commission Internationale d'Eclairage (CIE) color coordinates were found to be x, y = 0.17, 0.06-0.07, showing a good blue color. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Dynamical renormalization group approach to transport in ultrarelativistic plasmas: The electrical conductivity in high temperature QED

    International Nuclear Information System (INIS)

    Boyanovsky, Daniel; Vega, Hector J. de; Wang Shangyung

    2003-01-01

    The dc electrical conductivity of an ultrarelativistic QED plasma is studied in real time by implementing the dynamical renormalization group. The conductivity is obtained from the real-time dependence of a dissipative kernel closely related to the retarded photon polarization. Pinch singularities in the imaginary part of the polarization are manifest as secular terms that grow in time in the perturbative expansion of this kernel. The leading secular terms are studied explicitly and it is shown that they are insensitive to the anomalous damping of hard fermions as a result of a cancellation between self-energy and vertex corrections. The resummation of the secular terms via the dynamical renormalization group leads directly to a renormalization group equation in real time, which is the Boltzmann equation for the (gauge invariant) fermion distribution function. A direct correspondence between the perturbative expansion and the linearized Boltzmann equation is established, allowing a direct identification of the self-energy and vertex contributions to the collision term. We obtain a Fokker-Planck equation in momentum space that describes the dynamics of the departure from equilibrium to leading logarithmic order in the coupling. This equation determines that the transport time scale is given by t tr =24 π/e 4 T ln(1/e). The solution of the Fokker-Planck equation approaches asymptotically the steady-state solution as ∼e -t/(4.038...t tr ) . The steady-state solution leads to the conductivity σ=15.698 T/e 2 ln(1/e) to leading logarithmic order. We discuss the contributions beyond leading logarithms as well as beyond the Boltzmann equation. The dynamical renormalization group provides a link between linear response in quantum field theory and kinetic theory

  6. The effects of an external electric field on the dynamics of cold plasma jets—experimental and computational studies

    International Nuclear Information System (INIS)

    Naidis, G V; Walsh, J L

    2013-01-01

    Atmospheric pressure plasma jets provide a convenient and stable means to transport highly reactive plasma species beyond the confines of the plasma generating electrodes and into the ambient air; such characteristics make them an ideal tool for many emerging plasma processing applications. As the guided streamer exits the jet capillary, the application of an external electric field can significantly influence the dynamics of propagation, potentially providing a means to manipulate the transport of plasma species to a downstream substrate. In this paper the influence of positive and negative voltages pulses applied to an external electrode situated along the axis of streamer propagation is examined experimentally and computationally using a simplified 1.5D model. It is shown that application of a positive voltage pulse to the external electrode reduces the velocity of propagation of the cathode-directed streamer and the application of a negative voltage pulse increases the velocity of propagation. Further to this, the application of high positive voltages to the external electrodes effectively inhibits propagation and results in a significant decrease in the emission intensity from excited states populated by energetic electrons. The results obtained experimentally are compared and contrasted with those from the computational model to uncover the underlying physical mechanisms at play. (paper)

  7. A method of computer aided design with self-generative models in NX Siemens environment

    Science.gov (United States)

    Grabowik, C.; Kalinowski, K.; Kempa, W.; Paprocka, I.

    2015-11-01

    Currently in CAD/CAE/CAM systems it is possible to create 3D design virtual models which are able to capture certain amount of knowledge. These models are especially useful in an automation of routine design tasks. These models are known as self-generative or auto generative and they can behave in an intelligent way. The main difference between the auto generative and fully parametric models consists in the auto generative models ability to self-organizing. In this case design model self-organizing means that aside from the possibility of making of automatic changes of model quantitative features these models possess knowledge how these changes should be made. Moreover they are able to change quality features according to specific knowledge. In spite of undoubted good points of self-generative models they are not so often used in design constructional process which is mainly caused by usually great complexity of these models. This complexity makes the process of self-generative time and labour consuming. It also needs a quite great investment outlays. The creation process of self-generative model consists of the three stages it is knowledge and information acquisition, model type selection and model implementation. In this paper methods of the computer aided design with self-generative models in NX Siemens CAD/CAE/CAM software are presented. There are the five methods of self-generative models preparation in NX with: parametric relations model, part families, GRIP language application, knowledge fusion and OPEN API mechanism. In the paper examples of each type of the self-generative model are presented. These methods make the constructional design process much faster. It is suggested to prepare this kind of self-generative models when there is a need of design variants creation. The conducted research on assessing the usefulness of elaborated models showed that they are highly recommended in case of routine tasks automation. But it is still difficult to distinguish

  8. Flight Plasma Diagnostics for High-Power, Solar-Electric Deep-Space Spacecraft

    Science.gov (United States)

    Johnson, Lee; De Soria-Santacruz Pich, Maria; Conroy, David; Lobbia, Robert; Huang, Wensheng; Choi, Maria; Sekerak, Michael J.

    2018-01-01

    NASA's Asteroid Redirect Robotic Mission (ARRM) project plans included a set of plasma and space environment instruments, the Plasma Diagnostic Package (PDP), to fulfill ARRM requirements for technology extensibility to future missions. The PDP objectives were divided into the classes of 1) Plasma thruster dynamics, 2) Solar array-specific environmental effects, 3) Plasma environmental spacecraft effects, and 4) Energetic particle spacecraft environment. A reference design approach and interface requirements for ARRM's PDP was generated by the PDP team at JPL and GRC. The reference design consisted of redundant single-string avionics located on the ARRM spacecraft bus as well as solar array, driving and processing signals from multiple copies of several types of plasma, effects, and environments sensors distributed over the spacecraft and array. The reference design sensor types were derived in part from sensors previously developed for USAF Research Laboratory (AFRL) plasma effects campaigns such as those aboard TacSat-2 in 2007 and AEHF-2 in 2012.

  9. Electric sheath and presheath in a collisionless, finite ion temperature plasma

    International Nuclear Information System (INIS)

    Emmert, G.A.; Wieland, R.M.; Mense, A.T.; Davidson, J.N.

    1980-01-01

    The plasma-sheath equation for a collisionless plasma with arbitrary ion temperature in plane geometry is formulated. Outside the sheath, this equation is approximated by the plasma equation, for which an analytic solution for the electrostatic potential is obtained. In addition, the ion distribution function, the wall potential, and the ion energy and particle flux into the sheath are explicitly calculated. The plasma-sheath equation is also solved numerically with no approximation of the Debye length. The numerical results compare well with the analytical results when the Debye length is small

  10. The Role of an Electric Field in the Formation of a Detached Regime in Tokamak Plasma

    Science.gov (United States)

    Senichenkov, I.; Kaveeva, E.; Rozhansky, V.; Sytova, E.; Veselova, I.; Voskoboynikov, S.; Coster, D.

    2018-03-01

    Modeling of the transition to the detachment of ASDEX Upgrade tokamak plasma with increasing density is performed using the SOLPS-ITER numerical code with a self-consistent account of drifts and currents. Their role in plasma redistribution both in the confinement region and in the scrape-off layer (SOL) is investigated. The mechanism of high field side high-density formation in the SOL in the course of detachment is suggested. In the full detachment regime, when the cold plasma region expands above the X-point and reaches closed magnetic-flux surfaces, plasma perturbation in a confined region may lead to a change in the confinement regime.

  11. Electricity

    CERN Document Server

    Basford, Leslie

    2013-01-01

    Electricity Made Simple covers the fundamental principles underlying every aspect of electricity. The book discusses current; resistance including its measurement, Kirchhoff's laws, and resistors; electroheat, electromagnetics and electrochemistry; and the motor and generator effects of electromagnetic forces. The text also describes alternating current, circuits and inductors, alternating current circuits, and a.c. generators and motors. Other methods of generating electromagnetic forces are also considered. The book is useful for electrical engineering students.

  12. Use of a Monte-Carlo method for studying the statistical distribution of electric fields around an ion in a one-component plasma

    International Nuclear Information System (INIS)

    Rossignol-Guzzi, D.

    1968-11-01

    A Monte-Carlo simulation has been made of the equilibrium configurations taken by a plasma of equally charged punctual ions, immersed in a uniform neutralizing background of electrons. The statistical repartition of the electric field acting on one ion, needed to obtain Stark effect, was specially obtained. Comparison for dense plasmas, was made with the former works of Holtzmark, Mayer, Broyles. (author) [fr

  13. Self-generation of dissipative solitons in magnonic quasicrystal active ring resonator

    International Nuclear Information System (INIS)

    Grishin, S. V.; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P.; Nikitov, S. A.

    2014-01-01

    Self-generation of dissipative solitons in the magnonic quasicrystal (MQC) active ring resonator is studied theoretically and experimentally. The developed magnonic crystal has quasiperiodic Fibonacci type structure. Frequency selectivity of the MQC together with the parametric three-wave decay of magnetostatic surface spin wave (MSSW) leads to the dissipative soliton self-generation. The transfer matrix method is used to describe MQC transmission responses. Besides, the model of MQC active ring resonator is suggested. The model includes three coupled differential equations describing the parametric decay of MSSW and two differential equations of linear oscillators describing the frequency selectivity of MQC. Numerical simulation results of dissipative soliton self-generation are in a fair agreement with experimental data

  14. Self-generation of dissipative solitons in magnonic quasicrystal active ring resonator

    Energy Technology Data Exchange (ETDEWEB)

    Grishin, S. V., E-mail: grishfam@sgu.ru; Beginin, E. N.; Morozova, M. A.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Science, Moscow 125009 (Russian Federation)

    2014-02-07

    Self-generation of dissipative solitons in the magnonic quasicrystal (MQC) active ring resonator is studied theoretically and experimentally. The developed magnonic crystal has quasiperiodic Fibonacci type structure. Frequency selectivity of the MQC together with the parametric three-wave decay of magnetostatic surface spin wave (MSSW) leads to the dissipative soliton self-generation. The transfer matrix method is used to describe MQC transmission responses. Besides, the model of MQC active ring resonator is suggested. The model includes three coupled differential equations describing the parametric decay of MSSW and two differential equations of linear oscillators describing the frequency selectivity of MQC. Numerical simulation results of dissipative soliton self-generation are in a fair agreement with experimental data.

  15. The influence of electrical resistivity, magnetic field strength, boundary conditions, and injection conditions on the behavior of the magnetically injected plasma in the PBFA-II opening switch

    International Nuclear Information System (INIS)

    Watrous, J.J.; Frese, M.H.

    1993-01-01

    The Plasma Opening Switch used on PBFA-II uses a source plasma which is injected into the inter-electrode gap along the field lines of a modest-strength applied poloidal magnetic field. The distribution of this plasma within the gap plays an important role in the behavior of the switch. Knowledge of this distribution is critical for performing relevant switch calculations and for interpreting experimental data. In the work reported here, the influence on that distribution of the plasma electrical resistivity, the applied magnetic field strength, and the boundary and injection conditions have been investigated with the 2 1/2-dimensional magnetohydrodynamics simulation code, MACH2. The injected plasma has density in the 10 14 cm -3 range and temperature in the several eV range. In this parameter regime, the classical collision time scale is on the order of 10 ns, which, when compared to the 100 ns time scale of the inflowing plasma, means that the plasma is classically collisionless. However, mechanisms other than classical collisions are likely to contribute to electrical resistivity. The authors have investigated the effect of an anomalous resistivity which scales with the plasma frequency, varying the scaling from the electron plasma frequency to the ion plasma frequency. They will compare these results with results based on the assumption of an ideal plasma, and discuss other anomalous resistivity models

  16. Electric wind produced by surface plasma actuators: a new dielectric barrier discharge based on a three-electrode geometry

    International Nuclear Information System (INIS)

    Moreau, Eric; Sosa, Roberto; Artana, Guillermo

    2008-01-01

    Active flow control is a rapidly developing topic because the associated industrial applications are of immense importance, particularly for aeronautics. Among all the flow control methods, such as the use of mechanical flaps or wall jets, plasma-based devices are very promising devices. The main advantages of such systems are their robustness, their simplicity, their low-power consumption and that they allow a real-time control at high frequency. This paper deals with an experimental study about the electric wind produced by a surface discharge based on a three-electrode geometry. This new device is composed of a typical two-electrode surface barrier discharge excited by an AC high voltage, plus a third electrode at which a DC high voltage is applied in order to extend the discharge region and to accelerate the ion drift velocity. In the first part the electrical current of these different surface discharges is presented and discussed. This shows that the current behaviour depends on the DC component polarity. The second part is dedicated to analysing the electric wind characteristics through Schlieren visualizations and to measuring its time-averaged velocity with a Pitot tube sensor. The results show that an excitation of the electrodes with an AC voltage plus a positive DC component can significantly modify the topology of the electric wind produced by a single DBD. In practice, this DC component allows us to increase the value of the maximum induced velocity (up to +150% at a few centimetres downstream of the discharge) and the plasma extension, to enhance the depression occurring above the discharge region and to increase the discharge-induced mass flow rate (up to +100%), without increasing the electrical power consumption

  17. A model for the nonlocal transport and the associated distribution function deformation in magnetized laser-plasmas

    Science.gov (United States)

    Nicolaï, Ph.; Feugeas, J.-L.; Schurtz, G.

    2006-06-01

    We present a model of nonlocal transport for multidimensional radiation magneto hydrodynamic codes. In laser produced plasmas, it is now believed that the heat transfert can be strongly modified by the nonlocal nature of the electron conduction. Nevertheless other mechanisms as self generated magnetic fields may affect heat transport too. The model described in this work aims at extending the formula of G. Schurtz, Ph. Nicolaï and M. Busquet [1] to magnetized plasmas. A system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and applied to a physical problem in order to demonstrate the main features of the model.

  18. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    International Nuclear Information System (INIS)

    Catapano, F.; Zimbardo, G.; Artemyev, A. V.; Vasko, I. Y.

    2015-01-01

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed

  19. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    Energy Technology Data Exchange (ETDEWEB)

    Catapano, F., E-mail: menacata3@gmail.com; Zimbardo, G. [Dipartimento di Fisica, Università della Calabria, Rende, Cosenza (Italy); Artemyev, A. V., E-mail: ante0226@gmail.com; Vasko, I. Y. [Space Research Institute, RAS, Moscow (Russian Federation)

    2015-09-15

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed.

  20. Modification of surface characteristic and tribo-electric properties of polymers by DBD plasma in atmospheric air

    Science.gov (United States)

    Bekkara, Mohammed Fethi; Dascalescu, Lucien; Benmimoun, Youcef; Zeghloul, Thami; Tilmatine, Amar; Zouzou, Noureddine

    2018-01-01

    The aim of this paper is to quantify the effects of dielectric barrier discharge (DBD) exposure on the physico-chemical and tribo-electric properties of polymers. The study was conducted in atmospheric air on polypropylene, polyethylene and polyvinyl-chloride. These three types of polymers are widely used in industry. The polymers were characterized by means of an optical profilometer, a fourier-transform infrared (FTIR) spectrometer and an electric charge measurement system. The latter is composed of a Faraday pail connected to an electrometer. The profilometer analyses showed that the DBD plasma treatment has increased the surface roughness of the three polymers. FTIR revealed that oxygen atoms and polar groups were grafted on their surfaces, thereby conferring them a hydrophilic character. The short (2 sec) DBD plasma treatment has considerably improved the electrostatic charge acquired by the polymers during electrostatic tribo-charging, while longer exposures conferred the polymer anti-static properties and decreased its tribo-charging capability. The correlation between the results of the physico-chemical analyses and the tribo-electric behavior has been discussed.

  1. Attenuation of self-generated tactile sensations is predictive, not postdictive.

    Directory of Open Access Journals (Sweden)

    Paul M Bays

    2006-02-01

    Full Text Available When one finger touches the other, the resulting tactile sensation is perceived as weaker than the same stimulus externally imposed. This attenuation of sensation could result from a predictive process that subtracts the expected sensory consequences of the action, or from a postdictive process that alters the perception of sensations that are judged after the event to be self-generated. In this study we observe attenuation even when the fingers unexpectedly fail to make contact, supporting a predictive process. This predictive attenuation of self-generated sensation may have evolved to enhance the perception of sensations with an external cause.

  2. Attenuation of Self-Generated Tactile Sensations is Predictive, not Postdictive.

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available When one finger touches the other, the resulting tactile sensation is perceived as weaker than the same stimulus externally imposed. This attenuation of sensation could result from a predictive process that subtracts the expected sensory consequences of the action, or from a postdictive process that alters the perception of sensations that are judged after the event to be self-generated. In this study we observe attenuation even when the fingers unexpectedly fail to make contact, supporting a predictive process. This predictive attenuation of self-generated sensation may have evolved to enhance the perception of sensations with an external cause.

  3. Review of the methods to form hydrogen peroxide in electrical discharge plasma with liquid water

    Science.gov (United States)

    Locke, Bruce R.; Shih, Kai-Yuan

    2011-06-01

    This paper presents a review of the literature dealing with the formation of hydrogen peroxide from plasma processes. Energy yields for hydrogen peroxide generation by plasma from water span approximately three orders of magnitude from 4 × 10-2 to 80 g kWh-1. A wide range of plasma processes from rf to pulsed, ac, and dc discharges directly in the liquid phase have similar energy yields and may thus be limited by radical quenching processes at the plasma-liquid interface. Reactor modification using discharges in bubbles and discharges over the liquid phase can provide modest improvements in energy yield over direct discharge in the liquid, but the interpretation is complicated by additional chemical reactions of gas phase components such as ozone and nitrogen oxides. The highest efficiency plasma process utilizes liquid water droplets that may enhance efficiency by sequestering hydrogen peroxide in the liquid and by suppressing decomposition reactions by radicals from the gas and at the interface. Kinetic simulations of water vapor reported in the literature suggest that plasma generation of hydrogen peroxide should approach 45% of the thermodynamics limit, and this fact coupled with experimental studies demonstrating improvements with the presence of the condensed liquid phase suggest that further improvements in energy yield may be possible. Plasma generation of hydrogen peroxide directly from water compares favorably with a number of other methods including electron beam, ultrasound, electrochemical and photochemical methods, and other chemical processes.

  4. Review of the methods to form hydrogen peroxide in electrical discharge plasma with liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Locke, Bruce R; Shih, Kai-Yuan [Department of Chemical and Biomedical Engineering, Florida State University, Tallahassee, FL 32310 (United States)

    2011-06-15

    This paper presents a review of the literature dealing with the formation of hydrogen peroxide from plasma processes. Energy yields for hydrogen peroxide generation by plasma from water span approximately three orders of magnitude from 4 x 10{sup -2} to 80 g kWh{sup -1}. A wide range of plasma processes from rf to pulsed, ac, and dc discharges directly in the liquid phase have similar energy yields and may thus be limited by radical quenching processes at the plasma-liquid interface. Reactor modification using discharges in bubbles and discharges over the liquid phase can provide modest improvements in energy yield over direct discharge in the liquid, but the interpretation is complicated by additional chemical reactions of gas phase components such as ozone and nitrogen oxides. The highest efficiency plasma process utilizes liquid water droplets that may enhance efficiency by sequestering hydrogen peroxide in the liquid and by suppressing decomposition reactions by radicals from the gas and at the interface. Kinetic simulations of water vapor reported in the literature suggest that plasma generation of hydrogen peroxide should approach 45% of the thermodynamics limit, and this fact coupled with experimental studies demonstrating improvements with the presence of the condensed liquid phase suggest that further improvements in energy yield may be possible. Plasma generation of hydrogen peroxide directly from water compares favorably with a number of other methods including electron beam, ultrasound, electrochemical and photochemical methods, and other chemical processes.

  5. The influence of the geometry and electrical characteristics on the formation of the atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Sobota, A; Guaitella, O; Rousseau, A

    2014-01-01

    An extensive electrical study was performed on a coaxial geometry atmospheric pressure plasma jet source in helium, driven by 30 kHz sine voltage. Two modes of operation were observed, a highly reproducible low-power mode that features the emission of one plasma bullet per voltage period and an erratic high-power mode in which micro-discharges appear around the grounded electrode. The minimum of power transfer efficiency corresponds to the transition between the two modes. Effective capacitance was identified as a varying property influenced by the discharge and the dissipated power. The charge carried by plasma bullets was found to be a small fraction of charge produced in the source irrespective of input power and configuration of the grounded electrode. The biggest part of the produced charge stays localized in the plasma source and below the grounded electrode, in the range 1.2–3.3 nC for ground length of 3–8 mm. (paper)

  6. Potential of electric discharge plasma methods in abatement of volatile organic compounds originating from the food industry.

    Science.gov (United States)

    Preis, S; Klauson, D; Gregor, A

    2013-01-15

    Increased volatile organic compounds emissions and commensurate tightening of applicable legislation mean that the development and application of effective, cost-efficient abatement methods are areas of growing concern. This paper reviews the last two decades' publications on organic vapour emissions from food processing, their sources, impacts and treatment methods. An overview of the latest developments in conventional air treatment methods is presented, followed by the main focus of the paper, non-thermal plasma technology. The results of the review suggest that non-thermal plasma technology, in its pulsed corona discharge configuration, is an emerging treatment method with potential for low-cost, effective abatement of a wide spectrum of organic air pollutants. It is found that the combination of plasma treatment with catalysis is a development trend that demonstrates considerable potential. The as yet relatively small number of plasma treatment applications is considered to be due to the novelty of pulsed electric discharge techniques and a lack of reliable pulse generators and reactors. Other issues acting as barriers to widespread adoption of the technique include the possible formation of stable oxidation by-products, residual ozone and nitrogen oxides, and sensitivity towards air humidity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Effects of electron-electron interactions on the electron distribution function of a plasma in the presence of an external electric field

    International Nuclear Information System (INIS)

    Molinari, V.G.; Pizzio, F.; Spiga, G.

    1979-01-01

    The electron distribution function, the electron temperature and some transport parameters (electrical conductivity and energy flow coefficient) are obtained starting from the nonlinear Boltzmann equation for a plasma under the action of an external electric field. The Fokker-Planck approximation is used for electron-electron and electron-ion interactions. The effects of electron-electron collisions are studied for different values of collision frequencies and electric field. (author)

  8. A simple model of the plasma deflagration gun including self-consistent electric and magnetic fields

    International Nuclear Information System (INIS)

    Enloe, C.L.; Reinovsky, R.E.

    1985-01-01

    At the Air Force Weapons Laboratory, interest has continued for some time in energetic plasma injectors. A possible scheme for such a device is the plasma deflagration gun. When the question arose whether it would be possible to scale a deflagration gun to the multi-megajoule energy level, it became clear that a scaling law which described the fun as a circuit element and allowed one to confidently scale gun parameters would be required. The authors sought to develop a scaling law which self-consistently described the current, magnetic field, and velocity profiles in the gun. They based this scaling law on plasma parameters exclusively, abandoning the fluid approach

  9. Modeling of electron behaviors under microwave electric field in methane and air pre-mixture gas plasma assisted combustion

    Science.gov (United States)

    Akashi, Haruaki; Sasaki, K.; Yoshinaga, T.

    2011-10-01

    Recently, plasma-assisted combustion has been focused on for achieving more efficient combustion way of fossil fuels, reducing pollutants and so on. Shinohara et al has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power without increase of gas temperature. This suggests that electrons heated by microwave electric field assist the combustion. They also measured emission from 2nd Positive Band System (2nd PBS) of nitrogen during the irradiation. To clarify this mechanism, electron behavior under microwave power should be examined. To obtain electron transport parameters, electron Monte Carlo simulations in methane and air mixture gas have been done. A simple model has been developed to simulate inside the flame. To make this model simple, some assumptions are made. The electrons diffuse from the combustion plasma region. And the electrons quickly reach their equilibrium state. And it is found that the simulated emission from 2nd PBS agrees with the experimental result. Recently, plasma-assisted combustion has been focused on for achieving more efficient combustion way of fossil fuels, reducing pollutants and so on. Shinohara et al has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power without increase of gas temperature. This suggests that electrons heated by microwave electric field assist the combustion. They also measured emission from 2nd Positive Band System (2nd PBS) of nitrogen during the irradiation. To clarify this mechanism, electron behavior under microwave power should be examined. To obtain electron transport parameters, electron Monte Carlo simulations in methane and air mixture gas have been done. A simple model has been developed to simulate inside the flame. To make this model simple, some assumptions are made. The electrons diffuse from the combustion plasma region. And the electrons quickly reach their equilibrium state. And it is found

  10. Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

    Science.gov (United States)

    Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

    1982-01-01

    A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

  11. Radial electric field at the plasma edge on the FT-2 Tokamak in regimes with large gradients

    International Nuclear Information System (INIS)

    Lashkul, S.; Popov, A.

    2001-01-01

    The transport barrier formation is widely believed to be the fundamental element of transition into improved confinement regimes (H-mode). Experiments on many tokamaks demonstrate that transport barrier formation is connected with the suppression of turbulent transport by shear of E x B drift. Therefore, the calculation of radial electric field is of great importance. Our work is devoted to progress the neoclassical theory by taking into account electron viscosity and non-linear effects (ion inertia), presented results being valuable for interpretation transition into H-mode at the plasma edge in small tokamaks. Calculations of the electric field profile for FT-2 tokamak (a=8cm, R 0 =55cm, Ioffe Institute, Russia) according found expressions are in the good agreement with experimental results obtained. (orig.)

  12. Electron cyclotron waves in the presence of parallel electric fields in the Earth's auroral plasma

    Directory of Open Access Journals (Sweden)

    S. Kumar

    1997-01-01

    Full Text Available The electron cyclotron waves that originate at low altitudes (<0.5 RE and observed by ground facilities have been studied in the presence of a weak parallel electric field in auroral magnetoplasma consisting of trapped energetic auroral electrons and cold background electrons of ionospheric origin. The model distribution for auroral trapped electrons is taken as Maxwellian ring distribution. An expression for the growth rate has been obtained in the presence of parallel electric field assuming that the real frequency in the whistler mode is not affected by the presence of the electric field. The results show that waves grow (or damp in amplitude for a parallel (or antiparallel electric field. The influence of the electric field is more pronounced at a shorter wavelength spectrum. An increase in population of energetic electrons increases the growth rate and thus, plays a significant role in the wave excitation process in the auroral regions.

  13. Neutral Beam Source and Target Plasma for Development of a Local Electric Field Fluctuation Diagnostic

    Science.gov (United States)

    Bakken, M. R.; Burke, M. G.; Fonck, R. J.; Lewicki, B. T.; Rhodes, A. T.; Winz, G. R.

    2016-10-01

    A new diagnostic measuring local E-> (r , t) fluctuations is being developed for plasma turbulence studies in tokamaks. This is accomplished by measuring fluctuations in the separation of the π components in the Hα motional Stark spectrum. Fluctuations in this separation are expected to be Ẽ / ẼEMSE 10-3EMSE 10-3 . In addition to a high throughput, high speed spectrometer, the project requires a low divergence (Ω 0 .5°) , 80 keV, 2.5 A H0 beam and a target plasma test stand. The beam employs a washer-stack arc ion source to achieve a high species fraction at full energy. Laboratory tests of the ion source demonstrate repeatable plasmas with Te 10 eV and ne 1.6 ×1017 m-3, sufficient for the beam ion optics requirements. Te and ne scalings of the ion source plasma are presented with respect to operational parameters. A novel three-phase resonant converter power supply will provide 6 mA/cm2 of 80 keV H0 at the focal plane for pulse lengths up to 15 ms, with low ripple δV / 80 keV 0.05 % at 280 kHz. Diagnostic development and validation tests will be performed on a magnetized plasma test stand with 0.5 T field. The test chamber will utilize a washer-stack arc source to produce a target plasma comparable to edge tokamak plasmas. A bias-plate with programmable power supply will be used to impose Ẽ within the target plasma. Work supported by US DOE Grant DE-FG02-89ER53296.

  14. Interactions between plasma-treated carbon nanotubes and electrically neutral materials

    Science.gov (United States)

    Ogawa, Daisuke; Nakamura, Keiji

    2014-10-01

    A plasma treatment can create dangling bonds on the surface of carbon nanotubes (CNTs). The dangling bonds are so reactive that the bonds possibly interact with other neutral species even out of the plasma if the lifetime of the bonds is effectively long. In order to have good understandings with the interactions, we placed multi-wall CNTs (MWCNTs) in atmospheric dielectric barrier discharge that was created in a closed environment with the voltage at 5 kV. We set 50 W for the operating power and 15 minutes for the process time for this plasma treatment. Our preliminary results showed that the reaction between dangling bonds and neutrals likely occurred in the situation when CNTs were treated with argon plasma, and then exposed in a nitrogen-rich dry box. We did Fourier transform infrared (FTIR) spectroscopy after the treatments. The measurement showed that the spectrum with plasma-treated CNTs was different from pristine CNTs. This is an indication that the plasma-treated CNTs have reactive cites on the surface even after the discharge (~ minutes), and then the CNTs likely reacted with the neutral species that causes the different spectrum. In this poster, we will show more details from our results and further progresses from this research.

  15. 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.

  16. Modification of microstructure and electrical conductivity of plasma-sprayed YSZ deposit through post-densification process

    International Nuclear Information System (INIS)

    Ning Xianjin; Li Chengxin; Li Changjiu; Yang Guanjun

    2006-01-01

    4.5 mol% yttria-stabilized zirconia (YSZ) coating was deposited by atmospheric plasma spraying (APS) as an electrolyte for solid oxide fuel cells (SOFCs) applications. The post treatment was employed using zirconium and yttrium nitrate solution infiltration to densify the coating microstructure for improvement of gas permeability. The deposition of YSZ through nitrate in voids of the coating was examined. Microstructure of the as-sprayed and densified coatings was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of infiltrating treatment on coating microstructure and electrical conductivity was examined. The electrical conductivity of APS-sprayed YSZ coating at the direction perpendicular to coating surface was much lower than that of bulk materials. Post-densification treatment improved the electrical conductivity of YSZ coating by about 25% compared with as-sprayed coating. It was found that the deposition of YSZ resulting from decomposition of nitrate in the lamellar interface gaps was different from that in vertical cracks in lamella owing to the orthogonal feature of those two types of gaps. The nanopores were formed in the deposited YSZ in nonbonded interface gaps while large pores were residued in vertical cracks in splats. The microstructural examination suggests that nanopores in the deposited YSZ in nonbonded interfaces in the coating were isolated from each other, which led to the significant reduction of gas permeability after densification. Moreover, the nanocontacts between lamellae resulted in high contact resistance and limit improvement of electrical conductivity of the coating after densification

  17. Electrical characteristics and influence of the air-gap size in a trielectrode plasma curtain at atmospheric pressure

    International Nuclear Information System (INIS)

    Sosa, R; Artana, G; Grondona, D; Marquez, A; Kelly, H

    2009-01-01

    A study of the electrical characteristics of the trielectrode plasma curtain (TPC) discharge is presented. The influence of the air-gap size (for a fixed value of the inter-electrode distance) on the discharge behaviour has been exhaustively studied. The TPC discharge is based on the combination of a dielectric barrier discharge (DBD) with a corona discharge (CD) in a three electrode system, and basically it consists of the 'stretching' of a pure DBD by the action of a negative CD generated between the active electrode of the dielectric barrier and a remote third electrode. It was found that the general trend of the electrical characteristic curves (the average discharge current and the streamer frequency as functions of the AC and DC biasing voltages) was very similar for all the air-gap values considered. Our results indicate that the development of the TPC discharge requires two conditions: (a) the presence of a positive cycle of a well-developed DBD together with a CD where the remote electrode acts as the cathode and (b) a voltage drop between the DBD electrode and the remote electrode high enough to obtain an average electric field in the gap that must exceed a minimum average electric field value in the streamer channel necessary for its propagation across the gap (∼6.3 kV cm -1 in our experimental conditions).

  18. Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor

    International Nuclear Information System (INIS)

    Yang Ling; Zhou Xiao-Wei; Ma Xiao-Hua; Lv Ling; Zhang Jin-Cheng; Hao Yue; Cao Yan-Rong

    2017-01-01

    The new electrical degradation phenomenon of the AlGaN/GaN high electron mobility transistor (HEMT) treated by low power fluorine plasma is discovered. The saturated current, on-resistance, threshold voltage, gate leakage and breakdown voltage show that each experiences a significant change in a short time stress, and then keeps unchangeable. The migration phenomenon of fluorine ions is further validated by the electron redistribution and breakdown voltage enhancement after off-state stress. These results suggest that the low power fluorine implant ion stays in an unstable state. It causes the electrical properties of AlGaN/GaN HEMT to present early degradation. A new migration and degradation mechanism of the low power fluorine implant ion under the off-stress electrical stress is proposed. The low power fluorine ions would drift at the beginning of the off-state stress, and then accumulate between gate and drain nearby the gate side. Due to the strong electronegativity of fluorine, the accumulation of the front fluorine ions would prevent the subsequent fluorine ions from drifting, thereby alleviating further the degradation of AlGaN/GaN HEMT electrical properties. (paper)

  19. Laser light absorption and harmonic generation due to self-generated magnetic fields

    International Nuclear Information System (INIS)

    Kruer, W.L.; Estabrook, K.G.

    1977-01-01

    It is shown that self-generated magnetic fields can play a significant role in laser light absorption. Even normally incident light will then be resonantly absorbed. Computer simulations and theoretical estimates for this absorption and the concomitant harmonic generation are given for parameters characteristic of some recent experiments

  20. The Effect of College Students' Self-Generated Computerized Mind Mapping on Their Reading Achievement

    Science.gov (United States)

    Sabbah, Sabah Salman

    2015-01-01

    This study explored the potential effect of college students' self-generated computerized mind maps on their reading comprehension. It also investigated the subjects' attitudes toward generating computerized mind maps for reading comprehension. The study was conducted in response to the inability of the foundation-level students, who were learning…

  1. Using Self-Generated Cues to Facilitate Recall: A Narrative Review

    Science.gov (United States)

    Wheeler, Rebecca L.; Gabbert, Fiona

    2017-01-01

    We draw upon the Associative Network model of memory, as well as the principles of encoding-retrieval specificity, and cue distinctiveness, to argue that self-generated cue mnemonics offer an intuitive means of facilitating reliable recall of personally experienced events. The use of a self-generated cue mnemonic allows for the spreading activation nature of memory, whilst also presenting an opportunity to capitalize upon cue distinctiveness. Here, we present the theoretical rationale behind the use of this technique, and highlight the distinction between a self-generated cue and a self-referent cue in autobiographical memory research. We contrast this mnemonic with a similar retrieval technique, Mental Reinstatement of Context, which is recognized as the most effective mnemonic component of the Cognitive Interview. Mental Reinstatement of Context is based upon the principle of encoding-retrieval specificity, whereby the overlap between encoded information and retrieval cue predicts the likelihood of accurate recall. However, it does not incorporate the potential additional benefit of self-generated retrieval cues. PMID:29163254

  2. Using Self-Generated Cues to Facilitate Recall: A Narrative Review

    Directory of Open Access Journals (Sweden)

    Rebecca L. Wheeler

    2017-10-01

    Full Text Available We draw upon the Associative Network model of memory, as well as the principles of encoding-retrieval specificity, and cue distinctiveness, to argue that self-generated cue mnemonics offer an intuitive means of facilitating reliable recall of personally experienced events. The use of a self-generated cue mnemonic allows for the spreading activation nature of memory, whilst also presenting an opportunity to capitalize upon cue distinctiveness. Here, we present the theoretical rationale behind the use of this technique, and highlight the distinction between a self-generated cue and a self-referent cue in autobiographical memory research. We contrast this mnemonic with a similar retrieval technique, Mental Reinstatement of Context, which is recognized as the most effective mnemonic component of the Cognitive Interview. Mental Reinstatement of Context is based upon the principle of encoding-retrieval specificity, whereby the overlap between encoded information and retrieval cue predicts the likelihood of accurate recall. However, it does not incorporate the potential additional benefit of self-generated retrieval cues.

  3. KINETIC-J: A computational kernel for solving the linearized Vlasov equation applied to calculations of the kinetic, configuration space plasma current for time harmonic wave electric fields

    Science.gov (United States)

    Green, David L.; Berry, Lee A.; Simpson, Adam B.; Younkin, Timothy R.

    2018-04-01

    We present the KINETIC-J code, a computational kernel for evaluating the linearized Vlasov equation with application to calculating the kinetic plasma response (current) to an applied time harmonic wave electric field. This code addresses the need for a configuration space evaluation of the plasma current to enable kinetic full-wave solvers for waves in hot plasmas to move beyond the limitations of the traditional Fourier spectral methods. We benchmark the kernel via comparison with the standard k →-space forms of the hot plasma conductivity tensor.

  4. Sustainment dynamo reexamined: nonlocal electrical conductivity of plasma in a stochastic magnetic field

    International Nuclear Information System (INIS)

    Jacobson, A.R.; Moses, R.W.

    1984-01-01

    The plasma dynamo is both an intriguing and a practical concept. The intrigue derives from attempting to explain naturally occurring and man-made plasmas whose strong field-aligned currents j/sub parallel/ apparently disobey the most naive Ohm's law j/sub parallel/ = sigma/sub parallel/E/sub parallel/. The practical importance derives from the dynamo's role both in formation and in sustainment of reversed-field pinch (RFP) and Spheromak fusion plasmas. We will examine certain features of the documented quasi-steady discharges on ZT-40M, and RFP in apparent need of a sustainment dynamo. We will show that the tail electrons (which carry j/sub parallel/) are probably wandering (along stochastic B Vector-field lines) over much of the minor radius in one mean-free-path

  5. Edge radial electric field structure in quiescent H-mode plasmas in the DIII-D tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Burrell, K H [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); West, W P [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Doyle, E J [University of California, Los Angeles, CA 90095-1597 (United States); Austin, M E [University of Texas at Austin, Austin, TX 78712 (United States); DeGrassie, J S [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Gohil, P [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Greenfield, C M [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Groebner, R J [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Jayakumar, R [Lawrence Livermore National Laboratory, Livermore, CA 94551-9900 (United States); Kaplan, D H [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Lao, L L [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Leonard, A W [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Makowski, M A [Lawrence Livermore National Laboratory, Livermore, CA 94551-9900 (United States); McKee, G R [University of Wisconsin, Madison, WI 53706-1687 (United States); Solomon, W M [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Thomas, D M [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Rhodes, T L [University of California, Los Angeles, CA 90095-1597 (United States); Wade, M R [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wang, G [University of California, Los Angeles, CA 90095-1597 (United States); Watkins, J G [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Zeng, L [University of California, Los Angeles, CA 90095-1597 (United States)

    2004-05-01

    H-mode operation is the choice for next step tokamak devices based on either conventional or advanced tokamak physics. This choice, however, comes at a significant cost for both the conventional and advanced tokamaks because of the effects of edge localized modes (ELMs). ELMs can produce significant erosion in the divertor and can affect the {beta} limit and reduced core transport regions needed for advanced tokamak operation. Experimental results from DIII-D over the past four years have demonstrated a new operating regime, the quiescent H-mode (QH-mode) regime, that solves these problems. QH-mode plasmas have now been run for over 4 s (>30 energy confinement times). Utilizing the steady-state nature of the QH-mode edge allows us to obtain unprecedented spatial resolution of the edge ion profiles and the edge radial electric field, E{sub r}, by sweeping the edge plasma slowly past the view points of the charge exchange spectroscopy system. We have investigated the effects of direct edge ion orbit loss on the creation and sustainment of the QH-mode. Direct loss of ions injected into the velocity-space loss cone at the plasma edge is not necessary for creation or sustainment of the QH-mode. The direct ion orbit loss has little effect on the edge E{sub r} well. The E{sub r} at the bottom of the well in these cases is about -100 kV m{sup -1} compared with -20 to -30 kV m{sup -1} in the standard H-mode. The well is about 1 cm wide, which is close to the diameter of the deuteron gyro-orbit. We also have investigated the effect of changing edge triangularity by changing the plasma shape from upwardly biased single null to magnetically balanced double null. We have now achieved the QH-mode in these double-null plasmas. The increased triangularity allows us to increase pedestal density in QH-mode plasmas by a factor of about 2.5 and overall pedestal pressure by a factor of 2. Pedestal {beta} and {nu}{sup *} values matching the values desired for ITER have been achieved. In

  6. Plasma characteristics in an electrically asymmetric capacitive discharge sustained by multiple harmonics: operating in the very high frequency regime

    Science.gov (United States)

    Zhang, Yu-Ru; Hu, Yan-Ting; Gao, Fei; Song, Yuan-Hong; Wang, You-Nian

    2018-05-01

    A novel method, the so-called electrical asymmetry effect (EAE), is gaining increasing interest for realizing the separate control of the ion flux and ion energy. In this paper, a two-dimensional fluid model combined with the full set of Maxwell equations is used to investigate the plasma properties in an electrically asymmetric capacitive discharge sustained by multiple consecutive harmonics operating in the very high frequency regime. The results indicate that by increasing the total number of consecutive harmonics k, the modulation of the dc self-bias induced by changing {θ }1 (the relative phase of the fundamental frequency) becomes different, especially for k ≤slant 6. In a discharge driven by eight consecutive harmonics, the dc self-bias varies with a period 2π, and the most positive value appears at {θ }1 = 3π/2. In addition, with the electromagnetic effects taken into account, the plasma density shifts from edge-high to uniform when {θ }1 increases from 0 to π, and the maximum moves again towards the radial wall at {θ }1 = 3π/2. Moreover, the transient behavior of electrodynamics is also important for a better understanding of the EAE. Within a period, three positive peaks of {P}z are observed, which cause substantial ionization at similar places. {P}r is characterized by a pronounced peak at the end of the period, and the lowest peak value appears at {θ }1 = π. The results obtained in this work are important for improving the plasma processes by utilizing the EAE, especially when the higher order harmonics are included.

  7. Radial electric field and rotation of the ensemble of plasma particles in tokamak

    International Nuclear Information System (INIS)

    Sorokina, E. A.; Ilgisonis, V. I.

    2012-01-01

    The velocity of macroscopic rotation of an ensemble of charged particles in a tokamak in the presence of an electric field has been calculated in a collisionless approximation. It is shown that the velocity of toroidal rotation does not reduce to a local velocity of electric drift and has opposite directions on the inner and outer sides of the torus. This result is supplemented by an analysis of the trajectories of motion of individual particles in the ensemble, which shows that the passing and trapped particles of the ensemble acquire in the electric field, on the average, different toroidal velocities. For the trapped particles, this velocity is equal to that of electric drift in the poloidal magnetic field, while the velocity of passing particles is significantly different. It is shown that, although the electric-field-induced shift of the boundaries between trapped and passing particles in the phase space depends on the particle mass and charge and is, in the general case, asymmetric, this does not lead to current generation.

  8. Radio Frequency Trap for Containment of Plasmas in Antimatter Propulsion Systems Using Rotating Wall Electric Fields

    Science.gov (United States)

    Sims, William Herbert, III (Inventor); Martin, James Joseph (Inventor); Lewis, Raymond A. (Inventor)

    2003-01-01

    A containment apparatus for containing a cloud of charged particles comprises a cylindrical vacuum chamber having a longitudinal axis. Within the vacuum chamber is a containment region. A magnetic field is aligned with the longitudinal axis of the vacuum chamber. The magnetic field is time invariant and uniform in strength over the containment region. An electric field is also aligned with the longitudinal axis of the vacuum chamber and the magnetic field. The electric field is time invariant, and forms a potential well over the containment region. One or more means are disposed around the cloud of particles for inducing a rotating electric field internal to the vacuum chamber. The rotating electric field imparts energy to the charged particles within the containment region and compress the cloud of particles. The means disposed around the outer surface of the vacuum chamber for inducing a rotating electric field are four or more segments forming a segmented ring, the segments conforming to the outer surface of the vacuum chamber. Each of the segments is energized by a separate alternating voltage. The sum of the voltages imposed on each segment establishes the rotating field. When four segments form a ring, the rotating field is obtained by a signal generator applying a sinusoidal signal phase delayed by 90,180 and 270 degrees in sequence to the four segments.

  9. Electric field and temperature in a target induced by a plasma jet imaged using Mueller polarimetry

    NARCIS (Netherlands)

    Slikboer, E.T.; Sobota, A.; Guaitella, O.; Garcia-Caurel, E.

    2018-01-01

    Mueller polarimetry is used to investigate the behavior of an electro optic target (BSO crystal) under exposure of guided ionization waves produced by an atmospheric pressure plasma jet. For the first time, this optical technique is time resolved to obtain the complete Mueller matrix of the sample

  10. Electrical aspects of argon micro-cell plasma with applications in bio-medical technology

    NARCIS (Netherlands)

    Horiuchi, Y.; Dijk, van J.; Makabe, T.

    2003-01-01

    Argon micro-cell plasma (MCP) is believed to be a viable tool for performing micro-surgery. The non-thermal nature of the discharge allows an effective treatment of pathological tissue without causing thermal damage to its surroundings. This bio-medical application imposes a number of design

  11. The plasmon contribution to the electrical resistivity of dense, high-temperature plasmas

    International Nuclear Information System (INIS)

    Daveloza K, S.M.; Krikorian, R.; Ferro Fontan, C.

    1990-01-01

    The plasmon contribution to the resistivity of a dense, nonideal and degenerate plasma in the framework of the Quantum Boltzmann Equation is studied. Holstein's integral equation is presented and a rough estimate of the electron plasmon scattering rate is given, which extends to the quantum domain a previous heuristic derivation by Kurilenkov and Valuev. (Author)

  12. Plasma-deposited aluminum-doped zinc oxide : controlling nucleation, growth and electrical properties

    NARCIS (Netherlands)

    Ponomarev, M.

    2012-01-01

    In this work, the Expanding Thermal Plasma (ETP) deposition technique was employed to study the growth development of ZnO:Al thin film as a transparent conductive oxide layer for sustainable applications. Characteristic for ETP-grown ZnO:Al is a gradually reducing resistivity of the growing layer

  13. The influence of electric fields and neutral particles on the plasma sheath at ITER divertor conditions

    NARCIS (Netherlands)

    Shumack, A.E.

    2011-01-01

    The purpose of this thesis is to support the optimization of the ‘exhaust-pipe’, or so-called ‘divertor’, of the nuclear fusion experiment ITER, a large international fusion reactor now under construction in the south of France. We focus particularly on two ‘tools’ for optimization of the plasma

  14. The electrical Discharge Characteristics of the 3.5 KJ Electrothermal Plasma Gun Experiment

    International Nuclear Information System (INIS)

    Diab, F.; El-Aragi, G.M.; El-Kashef, G.M.; Saudy, A.H.

    2013-01-01

    In order to better understand the operating characteristics of an electrothermal plasma gun and its design, a variety of operation characteristics including ( the length of the capillary, applied voltage, diameter of the capillary tube, circuit inductance) were investigated to determine performance effects and viability in a real system. An Electrothermal Plasma Gun (ETG) is composed of a capillary discharge tube made of Teflon operated with simple RLC circuit. The device called Electrothermal Gun (ETG) which is composed of 4 capacitors (70 μF, 10 kV, 1.3 μH) connected in parallel to a plasma source by means of one high power plane transmission line by mean of a switch triggered by negative pulse 360/385 V. For the present studies a simple RLC was chosen, which allowed the circuit parameters to be easily measure d. The electrothermal discharge characteristics of the plasma gun operated in open air, So that at atmospheric pressure the main parameters were measured. The gun voltage and discharge current are measured with voltage divider and Rogowiski coil respectively. From the results recorded we found that, the current lagged the voltage i-e the plasma source has an inductive reactivity. Moreover, the current value was changed by changing the circuit parameters, including the discharge voltage and circuit inductance, and the wire properties such as the length and diameter. The maximum gun current ranged between (5 - 50 KA) according to the charging voltage of capacitors between (1-7 KV), a typical discharge times are on the order r of 125 μS.

  15. Non-uniform Erosion and Surface Evolution of Plasma-Facing Materials for Electric Propulsion

    Science.gov (United States)

    Matthes, Christopher Stanley Rutter

    A study regarding the surface evolution of plasma-facing materials is presented. Experimental efforts were performed in the UCLA Pi Facility, designed to explore the physics of plasma-surface interactions. The influence of micro-architectured surfaces on the effects of plasma sputtering is compared with the response of planar samples. Ballistic deposition of sputtered atoms as a result of geometric re-trapping is observed. This provides a self-healing mechanism of micro-architectured surfaces during plasma exposure. This result is quantified using a QCM to demonstrate the evolution of surface features and the corresponding influence on the instantaneous sputtering yield. The sputtering yield of textured molybdenum samples exposed to 300 eV Ar plasma is found to be roughly 1 of the 2 corresponding value of flat samples, and increases with ion fluence. Mo samples exhibited a sputtering yield initially as low as 0.22+/-8%, converging to 0.4+/-8% at high fluence. Although the yield is dependent on the initial surface structure, it is shown to be transient, reaching a steady-state value that is independent of initial surface conditions. A continuum model of surface evolution resulting from sputtering, deposition and surface diffusion is also derived to resemble the damped Kuramoto-Sivashinsky (KS) equation of non-linear dynamics. Linear stability analysis of the evolution equation provides an estimate of the selected wavelength, and its dependence on the ion energy and angle of incidence. The analytical results are confirmed by numerical simulations of the equation with a Fast Fourier Transform method. It is shown that for an initially flat surface, small perturbations lead to the evolution of a selected surface pattern that has nano- scale wavelength. When the surface is initially patterned by other means, the final resulting pattern is a competition between the "templated" pattern and the "self-organized" structure. Potential future routes of research are also

  16. Suppression and excitation of MHD activity with an electrically polarized electrode at the TCABR tokamak plasma edge

    International Nuclear Information System (INIS)

    Nascimento, I.C.; Kuznetsov, Yu.K.; Guimaraes-Filho, Z.O.; Chamaa-Neto, I. El; Usuriaga, O.; Fonseca, A.M.M.; Galvao, R.M.O.; Caldas, I.L.; Severo, J.H.F.; Semenov, I.B.; Ribeiro, C.; Heller, M.V.P.; Bellintani, V.; Elizondo, J.I.; Sanada, E.

    2007-01-01

    Two reproducible regimes of tokamak operation, with excitation or suppression of MHD activity can be obtained using a voltage-biased electrode inside the edge of the TCABR tokamak. The experiment was carried out adjusting the tokamak parameters to obtain two types of discharges: with strong or weak MHD activity, without biasing in both cases. The plasma current was adjusted to cover a range of safety factor from 2.9 up to 3.5, so that when biasing was applied the magnetic island (3,1) could interact with the edge barrier. The application of biasing in subsequent discharges of each type resulted in excitation or suppression of the MHD activity. The results show that the dominant modes are m = 2, n = 1 and m = 3, n = 1 for excitation and partial suppression, respectively. In both regimes a strong decrease in the radial electric field is detected with destruction of the transport barrier and of the improved confinement caused by different mechanisms. The measurements include temporal behaviour of edge transport, turbulence, poloidal electric and magnetic fields, edge density, radial electric fields and radial profile of H α line intensity. The explanation of the excitation and suppression processes is discussed in the paper

  17. Electrically conductive, black thermal control coatings for spacecraft applications. III - Plasma-deposited ceramic matrix

    Science.gov (United States)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1987-01-01

    Five black, electrically-conductive thermal control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consist of both organic and inorganic systems applied on titanium, aluminum, and glass/epoxy composite surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation, convective and combustive heating, and cryogenic conditions over a temperature range between -196 C and 538 C. Mechanical, physical, thermal, electrical, and thermooptical properties are presented for one of these coatings. This paper describes the preparation, characteristics, and spraying of iron titanate on titanium and aluminum, and presents performance results.

  18. Development of graph self-generating program of radiation sampling for geophysical prospecting with AutoLISP

    International Nuclear Information System (INIS)

    Zhou Hongsheng

    2009-01-01

    A program of self-generating graph of radiation sampling for geophysical prospecting is developed with AutoLISP, which is developed wholly by the author and can self-generate and explain sampling graphs. The program has largely increased drawing efficiency and can avoid the graph errors due to manual drawing. (authors)

  19. Distinguishing How from Why the Mind Wanders: A Process-Occurrence Framework for Self-Generated Mental Activity

    Science.gov (United States)

    Smallwood, Jonathan

    2013-01-01

    Cognition can unfold with little regard to the events taking place in the environment, and such self-generated mental activity poses a specific set of challenges for its scientific analysis in both cognitive science and neuroscience. One problem is that the spontaneous onset of self-generated mental activity makes it hard to distinguish the events…

  20. Combining plasma gasification and solid oxide cell technologies in advanced power plants for waste to energy and electric energy storage applications.

    Science.gov (United States)

    Perna, Alessandra; Minutillo, Mariagiovanna; Lubrano Lavadera, Antonio; Jannelli, Elio

    2018-03-01

    The waste to energy (WtE) facilities and the renewable energy storage systems have a strategic role in the promotion of the "eco-innovation", an emerging priority in the European Union. This paper aims to propose advanced plant configurations in which waste to energy plants and electric energy storage systems from intermittent renewable sources are combined for obtaining more efficient and clean energy solutions in accordance with the "eco-innovation" approach. The advanced plant configurations consist of an electric energy storage (EES) section based on a solid oxide electrolyzer (SOEC), a waste gasification section based on the plasma technology and a power generation section based on a solid oxide fuel cell (SOFC). The plant configurations differ for the utilization of electrolytic hydrogen and oxygen in the plasma gasification section and in the power generation section. In the first plant configuration IAPGFC (Integrated Air Plasma Gasification Fuel Cell), the renewable oxygen enriches the air stream, that is used as plasma gas in the gasification section, and the renewable hydrogen is used to enrich the anodic stream of the SOFC in the power generation section. In the second plant configuration IHPGFC (Integrated Hydrogen Plasma Gasification Fuel Cell) the renewable hydrogen is used as plasma gas in the plasma gasification section, and the renewable oxygen is used to enrich the cathodic stream of the SOFC in the power generation section. The analysis has been carried out by using numerical models for predicting and comparing the systems performances in terms of electric efficiency and capability in realizing the waste to energy and the electric energy storage of renewable sources. Results have highlighted that the electric efficiency is very high for all configurations (35-45%) and, thanks to the combination with the waste to energy technology, the storage efficiencies are very attractive (in the range 72-92%). Copyright © 2017 Elsevier Ltd. All rights

  1. Investigation of the residue in an electric railgun employing a plasma armature

    International Nuclear Information System (INIS)

    Bauer, D.P.; Barber, J.P.

    1984-01-01

    This paper examines the performance of DC electric railguns using plasmaarmature-accelerated projectiles. The adverse effects on performance of a black residue produced in the railgun are examined. The residue appears to be responsible for causing secondary current paths within the railgun. The secondary current paths result in muzzle velocities lower than predicted

  2. Electrical transverse transport in Lorentz plasma with strong magnetic field and collision effect

    International Nuclear Information System (INIS)

    Xie, Baisong; Chong, L.V.; Li, Ziliang

    2015-01-01

    In inertial confinement fusion (ICF), the spontaneous magnetic field formed from laser interacting with the pellet may reach few hundreds of Megagauss (MG) which results in the cyclotron frequency ω at the same order of the collision frequency υ. Electrical transverse transport in this case would become very important so that we study it by the Boltzmann equation for different electron density distribution. For the Maxwell distribution, it is shown that transport coefficients decrease with the increase of Ω (the ratio of ω to υ), which means the electrons would be highly collimated by strong magnetic field. This is attributed to that the electron's gyroradius is smaller than the collisional mean free paths. Moreover, the electrical transverse transport is also studied for quasi-monoenergy distribution with different width ε, which is different from the Maxwell one. It is found that the transport coefficients decrease greatly as quasi-monoenergy degree increases. In particular when ε approaches to zero, i.e. the Delta distribution with almost perfect monoenergy electron density, the electric conductivity doesn't change while the thermal conductivity decreases with Ω. On the other hand the smaller the ε is the less amount the transverse transport exhibits. Our study indicates that they are beneficial to limit the electric transverse transport. (author)

  3. Electricity

    International Nuclear Information System (INIS)

    Tombs, F.

    1983-01-01

    The subject is discussed, with particular reference to the electricity industry in the United Kingdom, under the headings; importance and scope of the industry's work; future fuel supplies (estimated indigenous fossil fuels reserves); outlook for UK energy supplies; problems of future generating capacity and fuel mix (energy policy; construction programme; economics and pricing; contribution of nuclear power - thermal and fast reactors; problems of conversion of oil-burning to coal-burning plant). (U.K.)

  4. Optimization of confinement in a toroidal plasma subject to strong radial electric fields

    International Nuclear Information System (INIS)

    Roth, J.R.

    1977-01-01

    A preliminary report on the identification and optimization of independent variables which affect the ion density and confinement time in a bumpy torus plasma is presented. The independent variables include the polarity, position, and number of the midplane electrode rings, the method of gas injection, and the polarity and strength of a weak vertical magnetic field. Some characteristic data taken under condition when most of the independent variables were optimized are presented. The highest value of the electron number density on the plasma axis is 3.2 x 10 to the 12th power/cc, the highest ion heating efficiency is 47 percent, and the longest particle containment time is 2.0 milliseconds

  5. Electrical conductivity and charge carrier screening in weakly non-ideal argon plasmas

    International Nuclear Information System (INIS)

    Guenther, K.; Lang, S.; Radtke, R.

    1983-01-01

    A pulsed argon discharge as a stable source of weakly non-ideal plasmas is described in connection with the diagnostic necessities for conductivity measurements. The parameters overlap the range for stationary arcs and allow comparison with measurements in cascade arcs. The measured conductivities are explained using the binary collision model considering collisions with neutrals, excited atoms, and ions. A relation between the screening parameter and non-ideality is proposed which should be valid for all elements. (author)

  6. Electrical conductivity and charge carrier screening in weakly non-ideal argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, K; Lang, S; Radtke, R [Akademie der Wissenschaften der DDR, Jena. Zentralinstitut fuer Elektronenphysik

    1983-07-14

    A pulsed argon discharge as a stable source of weakly non-ideal plasmas is described in connection with the diagnostic necessities for conductivity measurements. The parameters overlap the range for stationary arcs and allow comparison with measurements in cascade arcs. The measured conductivities are explained using the binary collision model considering collisions with neutrals, excited atoms, and ions. A relation between the screening parameter and non-ideality is proposed which should be valid for all elements.

  7. Investigating Turkish Primary School Students' Interest in Science by Using Their Self-Generated Questions

    Science.gov (United States)

    Cakmakci, Gultekin; Sevindik, Hatice; Pektas, Meryem; Uysal, Asli; Kole, Fatma; Kavak, Gamze

    2012-06-01

    This paper reports on an attempt to investigate Turkish primary school students' interest in science by using their self-generated questions. We investigated students' interest in science by analyzing 1704 self-generated science-related questions. Among them, 826 questions were submitted to a popular science magazine called Science and Children. Such a self-selected sample may represent a group of students who have a higher level of motivation to seek sources of information outside their formal education and have more access to resources than the students of low social classes. To overcome this problem, 739 students were asked to write a question that they wanted to learn from a scientist and as a result 878 questions were gathered. Those students were selected from 13 different schools at 9 cities in Turkey. These schools were selected to represent a mixture of socioeconomic areas and also to cover different students' profile. Students' questions were classified into two main categories: the field of interest and the cognitive level of the question. The results point to the popularity of biology, astrophysics, nature of scientific inquiry, technology and physics over other science areas, as well as indicating a difference in interest according to gender, grade level and the setting in which the questions were asked. However, our study suggests that only considering questions submitted to informal learning environments, such as popular science magazines or Ask-A-Scientist Internet sites has limitations and deficiencies. Other methodologies of data collection also need to be considered in designing teaching and school science curriculum to meet students' needs and interest. The findings from our study tend to challenge existing thinking from other studies. Our results show that self-generated questions asked in an informal and a formal setting have different patterns. Some aspects of students' self-generated questions and their implications for policy, science

  8. Calculations of self-generated magnetic fields in parylene disc experiments

    International Nuclear Information System (INIS)

    Dahlbacka, G.H.; Mead, W.C.; Max, C.E.; Thomson, J.J.

    1975-01-01

    Experiments have been planned at Livermore to measure self-generated magnetic fields using the Faraday Rotation of frequency quadrupled 1.1 μm laser light. The LASNEX code was used during the planning of these experiments and has provided valuable information in establishing the conditions under which the thermoelectric fields expected can be measured. Suspected thermoelectric fields have been inferred from experiments that have been carried out at NRL

  9. Self-generated magnetic flux in YBa$_2$Cu$_3$O$_{7-x}$ grain boundaries

    OpenAIRE

    Mints, R. G.; Papiashvili, Ilya

    2000-01-01

    Grain boundaries in YBa$_2$Cu$_3$O$_{7-x}$ superconducting films are considered as Josephson junctions with a critical current density $j_c(x)$ alternating along the junction. A self-generated magnetic flux is treated both analytically and numerically for an almost periodic distribution of $j_c(x)$. We obtained a magnetic flux-pattern similar to the one which was recently observed experimentally.

  10. Confronting Conceptual Challenges in Thermodynamics by Use of Self-Generated Analogies

    Science.gov (United States)

    Haglund, Jesper; Jeppsson, Fredrik

    2014-07-01

    Use of self-generated analogies has been proposed as a method for students to learn about a new subject by reference to what they previously know, in line with a constructivist perspective on learning and a resource perspective on conceptual change. We report on a group exercise on using completion problems in combination with self-generated analogies to make sense of two thermodynamic processes. The participants (N = 8) were preservice physics teacher students at the fourth year of the teacher education program. The students experienced challenges in accounting for the constant entropy in reversible, adiabatic expansion of an ideal gas and the constant temperature in free, adiabatic expansion of an ideal gas. These challenges were found to be grounded in the students' intuitive understanding of the phenomena. In order to come to terms with the constant entropy in the first process, the students developed idiosyncratic explanations, but these could by properly adjusted given suitable scaffolding. In contrast, the students by themselves managed to make sense of the constant temperature in free expansion, by use of microscopic explanatory models. As a conclusion, self-generated analogies were found to provide a useful approach to identifying challenges to understanding among students, but also for the students to come to terms with these challenges. The results are discussed against a background of different perspectives on the issue of conceptual change in science education.

  11. Influence of COMT genotype and affective distractors on the processing of self-generated thought.

    Science.gov (United States)

    Kilford, Emma J; Dumontheil, Iroise; Wood, Nicholas W; Blakemore, Sarah-Jayne

    2015-06-01

    The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val(158)Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function. © The Author (2014). Published by Oxford University Press.

  12. The roles of electric field shear and Shafranov shift in sustaining high confinement in enhanced reversed shear plasmas on the TFTR tokamak

    International Nuclear Information System (INIS)

    Synakowski, E.J.; Beer, M.A.

    1997-02-01

    The relaxation of core transport barriers in TFTR Enhanced Reversed Shear plasmas has been studied by varying the radial electric field using different applied torques from neutral beam injection. Transport rates and fluctuations remain low over a wide range of radial electric field shear, but increase when the local E x B shearing rates are driven below a threshold comparable to the fastest linear growth rates of the dominant instabilities. Shafranov-shift-induced stabilization alone is not able to sustain enhanced confinement

  13. The transport of phosphate between the plasma and dialysate compartments in peritoneal dialysis is influenced by an electric potential difference

    DEFF Research Database (Denmark)

    Graff, J; Fugleberg, S; Brahm, J

    1996-01-01

    was not identifiable. Furthermore, it was demonstrated that the electrochemical gradient between plasma water and dialysate favours the diffusive phosphate transport, and both electric and chemical potentials must be taken into account in calculations of the transperitoneal phosphate transport.......Six kinetic models of transperitoneal phosphate transport were formulated and validated on the basis of experimental results obtained from 22 non-diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective......, and lymphatic convective phosphate transport. Calculations allowed for a 20% protein binding of phosphate. The validation procedure demonstrated that only diffusive and non-lymphatic convective phosphate transport mechanisms were identifiable. A lymphatic convective phosphate transport mechanism...

  14. Electron cyclotron wave absorption by the fast tail generated by the dc electric field in tokamak plasmas

    International Nuclear Information System (INIS)

    Giruzzi, G.; Krivenski, V.; Fidone, I.; Ziebell, L.F.

    1985-03-01

    Wave damping near the electron gyrofrequency in a tokamak plasma with the energetic tail generated by the dc electric field is investigated. The electron tail is computed by a Fokker-Planck initial value code as a function of the relevant parameter Esub(parallel)/Esub(c)=Esub(parallel)Tsub(e)/(2πsub(e)c 3 Λ). It is shown that in most cases of physical interest strong damping of the e-mode occurs for oblique propagation. The results are of relevance for studies of ECRH in present-day tokamaks and in future reactors where a mildly relativistic electron tail is naturally present for large tsub(e). Special emphasis is therefore given to wave absorption for frequencies f significantly below the central electron gyrofrequency, and to the associated rf-driven current

  15. Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas

    International Nuclear Information System (INIS)

    Li, C. K.; Seguin, F. H.; Frenje, J. A.; Manuel, M.; Casey, D.; Sinenian, N.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Rygg, J. R.; Town, R. P. J.; Betti, R.; Meyerhofer, D. D.; Delettrez, J.; Knauer, J. P.; Marshall, F.; Sangster, T. C.; Smalyuk, V. A.; Soures, J. M.; Shvarts, D.

    2009-01-01

    Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields produced in laser-foil interactions and during the implosion of inertial-confinement-fusion capsules. These experiments resulted in the first observations of several new and important features: (1) observations of the generation, decay dynamics, and instabilities of megagauss B fields in laser-driven planar plastic foils, (2) the observation of radial E fields inside an imploding capsule, which are initially directed inward, reverse direction during deceleration, and are likely related to the evolution of the electron pressure gradient, and (3) the observation of many radial filaments with complex electromagnetic field striations in the expanding coronal plasmas surrounding the capsule. The physics behind and implications of such observed fields are discussed.

  16. Resonance localization and poloidal electric field due to cyclo- tron wave heating in tokamak plasmas

    International Nuclear Information System (INIS)

    Hsu, J.Y.; Chan, V.S.; Harvey, R.W.; Prater, R.; Wong, S.K.

    1984-01-01

    The perpendicular heating in cyclotron waves tends to pile up the resonant particles toward the low magnetic field side with their banana tips localized to the resonant surface. A poloidal electric field with an E x B drift comparable to the ion vertical drift in a toroidal magnetic field may result. With the assumption of anomalous electron and neoclassical ion transport, density variations due to wave heating are discussed

  17. Dynamics of particle production by strong electric fields in non-Abelian plasmas

    International Nuclear Information System (INIS)

    Dawson, John F.; Mihaila, Bogdan; Cooper, Fred

    2010-01-01

    We develop methods for computing the dynamics of fermion pair production by strong color electric fields including backreaction using the semiclassical Boltzmann-Vlasov (B-V) equation. We implement the Schwinger pair production by inserting a source term in the B-V equation which includes Pauli-Blocking effects. We present numerical results for a model with SU(2) symmetries in (1+1) Cartesian dimensions.

  18. On improved confinement in mirror plasmas by a radial electric field

    Science.gov (United States)

    Ågren, O.; Moiseenko, V. E.

    2017-11-01

    A weak radial electric field can suppress radial excursions of a guiding center from its mean magnetic surface. The physical origin of this effect is the smearing action by a poloidal E × B rotation, which tend to cancel out the inward and outward radial drifts. A use of this phenomenon may provide larger margins for magnetic field shaping with radial confinement of particles maintained in the collision free idealization. Mirror fields, stabilized by a quadrupolar field component, are of particular interest for their MHD stability and the possibility to control the quasi neutral radial electric field by biased potential plates outside the confinement region. Flux surface footprints on the end tank wall have to be traced to avoid short-circuiting between biased plates. Assuming a robust biasing procedure, moderate voltage demands for the biased plates seems adequate to cure even the radial excursions of Yushmanov ions which could be locally trapped near the mirrors. Analytical expressions are obtained for a magnetic quadrupolar mirror configuration which possesses minimal radial magnetic drifts in the central confinement region. By adding a weak controlled radial quasi-neutral electric field, the majority of gyro centers are predicted to be forced to move even closer to their respective mean magnetic surface. The gyro center radial coordinate is in such a case an accurate approximation for a constant of motion. By using this constant of motion, the analysis is in a Vlasov description extended to finite β. A correspondence between that Vlasov system and a fluid description with a scalar pressure and an electric potential is verified. The minimum B criterion is considered and implications for flute mode stability in the considered magnetic field is analyzed. By carrying out a long-thin expansion to a higher order, the validity of the calculations are extended to shorter and more compact device designs.

  19. Radio Frequency (RF) Trap for Confinement of Antimatter Plasmas Using Rotating Wall Electric Fields

    Science.gov (United States)

    Sims, William Herbert, III; Pearson, J. Boise

    2004-01-01

    Perturbations associated with a rotating wall electric field enable the confinement of ions for periods approaching weeks. This steady state confinement is a result of a radio frequency manipulation of the ions. Using state-of-the-art techniques it is shown that radio frequency energy can produce useable manipulation of the ion cloud (matter or antimatter) for use in containment experiments. The current research focuses on the improvement of confinement systems capable of containing and transporting antimatter.

  20. Radial density distribution of a warm dense plasma formed by underwater electrical explosion of a copper wire

    Science.gov (United States)

    Nitishinskiy, M.; Yanuka, D.; Virozub, A.; Krasik, Ya. E.

    2017-12-01

    Time- and space-resolved evolution of the density (down to 0.07 of solid state density) of a copper wire during its microsecond timescale electrical explosion in water was obtained by X-ray backlighting. In the present research, a flash X-ray source of 20 ns pulse-width and >60 keV photon energy was used. The conductivity of copper was evaluated for a temperature of 10 kK and found to be in good agreement with the data obtained in earlier experiments [DeSilva and Katsouros, Phys. Rev. E 57, 5945 (1998) and Sheftman and Krasik, Phys. Plasmas 18, 092704 (2011)] where only electrical and optical diagnostics were applied. Magneto-hydrodynamic simulation shows a good agreement between the simulated and experimental waveforms of the current and voltage and measured the radial expansion of the exploding wire. Also, the radial density distribution obtained by an inverse Abel transform analysis agrees with the results of these simulations. Thus, the validity of the equations of state for copper and the conductivity model used in the simulations was confirmed for the parameters of the exploding wire realized in the present research.

  1. Electrical time resolved metrology of dust particles growing in low pressure cold plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Wattieaux, Gaeetan [PRISME, Orleans University, 12 rue de Blois BP 6744, 45067 Orleans cedex 2 (France); Mezeghrane, Abdelaziz [LPCQ, Mouloud Mammeri University, Tizi-Ouzou (Algeria); Boufendi, Laiefa [GREMI, Orleans University, 14 rue d' Issoudun BP 6744, 45067 Orleans cedex 2 (France)

    2011-09-15

    The electrical parameters of a capacitively coupled radiofrequency (CCRF) discharge change significantly when dust arises in the discharge. This work demonstrates the ability to follow in real time the evolution of the size and of the concentration of dust particles forming in a CCRF discharge from the variation of the electron density and of the self-bias voltage of the active electrode. According to experimental findings, it appears that the variation of this self-bias voltage depends on the surface of the dust particles. This trend is confirmed by an analytical modelling considering the low frequency behaviour of the phenomenon.

  2. Effects of non-thermal plasmas and electric field on hydrocarbon/air flames

    Science.gov (United States)

    Ganguly, Biswa

    2009-10-01

    Need to improve fuel efficiency, and reduce emission from hydrocarbon combustor in automotive and gas turbine engines have reinvigorated interest in reducing combustion instability of a lean flame. The heat generation rate in a binary reaction is HQ =N^2 c1c2 Q exp(-E/RT), where N is the density, c1 and c2 are mol fractions of the reactants, Q is the reaction heat release, E is the activation energy, R is the gas constant and T is the average temperature. For hydrocarbon-air reactions, the typical value of E/R ˜20, so most heat release reactions are confined to a thin reaction sheet at T >=1400 K. The lean flame burning condition is susceptible to combustion instability due to a critical balance between heat generation and heat loss rates, especially at high gas flow rate. Radical injection can increase flame speed by reducing the hydrocarbon oxidation reaction activation barrier and it can improve flame stability. Advances in nonequilibrium plasma generation at high pressure have prompted its application for energy efficient radical production to enhance hydrocarbon-air combustion. Dielectric barrier discharges and short pulse excited corona discharges have been used to enhance combustion stability. Direct electron impact dissociation of hydrocarbon and O2 produces radicals with lower fuel oxidation reaction activation barriers, initiating heat release reaction CnHm+O CnHm-1+ OH (and other similar sets of reactions with partially dissociated fuel) below the typical cross-over temperature. Also, N2 (A) produced in air discharge at a moderate E/n can dissociate O2 leading to oxidation of fuel at lower gas temperature. Low activation energy reactions are also possible by dissociation of hydrocarbon CnHm+e -> CnHm-2+H2+e, where a chain propagation reaction H2+ O OH+H can be initiated at lower gas temperature than possible under thermal equilibrium kinetics. Most of heat release comes from the reaction CO+OH-> CO2 +H, nonthermal OH production seem to improve

  3. Multi-machine studies of the role of turbulence and electric fields in the establishment of improved confinement in tokamak plasma

    Czech Academy of Sciences Publication Activity Database

    Van Oost, G.; Bulanin, V.V.; Donné, A.J.H.; Gusakov, E.Z.; Kraemer-Flecken, A.; Krupnik, L.I.; Melnikov, A.; Nanobashvili, S.; Peleman, P.; Razumova, K.A.; Stöckel, Jan; Vershkov, V.; Adámek, Jiří; Altukov, A.B.; Andreev, V.F.; Askinazi, L.G.; Bondarenko, I.S.; Brotánková, Jana; Dnestrovskij, A.Yu.; Ďuran, Ivan; Eliseev, L.G.; Esipov, L.A.; Grashin, S.A.; Gurchenko, A.D.; Hogeweij, G.M.D.; Hron, Martin; Ionita, C.; Jachmich, S.; Khrebtov, S.M.; Kouprienko, D.V.; Lysenko, S.E.; Martines, E.; Perfilov, S.V.; Petrov, A.V.; Popov, A.Yu.; Reiser, D.; Schrittwieser, R.; Soldatov, S.; Spolaore, M.; Stepanov, A.Yu.; Telesca, G.; Urazbaev, A.O.; Verdoolaege, G.; Žáček, František; Zimmermann, O.

    2007-01-01

    Roč. 49, 5A (2007), A29-A44 ISSN 0741-3335. [International Congress on Plasma Physics/13th./. Kiev, 22.05.2006-26.05.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * turbulence * electric fields Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.070, year: 2007

  4. Enhanced sensing of dengue virus DNA detection using O{sub 2} plasma treated-silicon nanowire based electrical biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, S.F.A., E-mail: siti_fatimah0410@yahoo.com [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Yusof, N.A., E-mail: azahy@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Hashim, U. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia); Hushiarian, R. [La Trobe Institute for Molecular Science, La Trobe University, Victoria, 3086 (Australia); Nuzaihan, M.N.M. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia); Hamidon, M.N. [Institute of Advanced Technology, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Zawawi, R.M. [Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, UPM, Serdang, Selangor (Malaysia); Fathil, M.F.M. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, 01000, Kangar, Perlis (Malaysia)

    2016-10-26

    Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis. To transform the fabricated devices as a functional sensing element, three-step procedure consist of SiNW surface modification, DNA immobilization and DNA hybridization were employed. The detection principle works by detecting the changes in current of SiNW which bridge the source and drain terminal to sense the immobilization of probe DNA and their hybridization with target DNA. The oxygen (O{sub 2}) plasma was proposed as an effective strategy for increasing the binding amounts of target DNA by modified the SiNW surface. It was found that the detection limit of the optimized O{sub 2} plasma treated-SiNW device could be reduced to 1.985 × 10{sup −14} M with a linear detection range of the sequence-specific DNA from 1.0 × 10{sup −9} M to 1.0 × 10{sup −13} M. In addition, the developed biosensor device was able to discriminate between complementary, single mismatch and non-complementary DNA sequences. This highly sensitive assay was then applied to the detection of reverse transcription-polymerase chain reaction (RT-PCR) product of DENV-DNA, making it as a potential method for disease diagnosis through electrical biosensor. - Highlights: • Molecular electronic detection of Dengue Virus (DENV) DNA using SiNW biosensor is presented. • Oxygen plasma surface treatment as an enhancer technique for device sensitivity is highlighted. • The limit of detection (Lo

  5. Enhanced sensing of dengue virus DNA detection using O_2 plasma treated-silicon nanowire based electrical biosensor

    International Nuclear Information System (INIS)

    Rahman, S.F.A.; Yusof, N.A.; Hashim, U.; Hushiarian, R.; Nuzaihan, M.N.M.; Hamidon, M.N.; Zawawi, R.M.; Fathil, M.F.M.

    2016-01-01

    Dengue Virus (DENV) has become one of the most serious arthropod-borne viral diseases, causing death globally. The existing methods for DENV detection suffer from the late stage treatment due to antibodies-based detection which is feasible only after five days following the onset of the illness. Here, we demonstrated the highly effective molecular electronic based detection utilizing silicon nanowire (SiNW) integrated with standard complementary metal-oxide-semiconductor (CMOS) process as a sensing device for detecting deoxyribonucleic acid (DNA) related to DENV in an early stage diagnosis. To transform the fabricated devices as a functional sensing element, three-step procedure consist of SiNW surface modification, DNA immobilization and DNA hybridization were employed. The detection principle works by detecting the changes in current of SiNW which bridge the source and drain terminal to sense the immobilization of probe DNA and their hybridization with target DNA. The oxygen (O_2) plasma was proposed as an effective strategy for increasing the binding amounts of target DNA by modified the SiNW surface. It was found that the detection limit of the optimized O_2 plasma treated-SiNW device could be reduced to 1.985 × 10"−"1"4 M with a linear detection range of the sequence-specific DNA from 1.0 × 10"−"9 M to 1.0 × 10"−"1"3 M. In addition, the developed biosensor device was able to discriminate between complementary, single mismatch and non-complementary DNA sequences. This highly sensitive assay was then applied to the detection of reverse transcription-polymerase chain reaction (RT-PCR) product of DENV-DNA, making it as a potential method for disease diagnosis through electrical biosensor. - Highlights: • Molecular electronic detection of Dengue Virus (DENV) DNA using SiNW biosensor is presented. • Oxygen plasma surface treatment as an enhancer technique for device sensitivity is highlighted. • The limit of detection (LoD) as low as 1.985

  6. Lectures in plasma diagnostics

    International Nuclear Information System (INIS)

    Hutchinson, I.H.

    1990-06-01

    This paper discusses the following topics on plasma diagnostics: Electric probes in flowing and magnetized plasmas; Electron cyclotron emission absorption; Magnetic diagnostics; Spectroscopy; and Thomson Scattering

  7. Overview on the radial electric field, plasma rotation and transport in the stellarator W7-AS

    International Nuclear Information System (INIS)

    Baldzuhn, J.; Kick, M.; Maassberg, H.; Ohlendorf, W.

    1998-01-01

    In the advanced stellarator W7-AS the radial electric field E r is measured by active charge exchange recombination spectroscopy CXRS. In parallel, it is calculated by using the neoclassical DKES code. A comparison of calculated and measured solutions reveals in how far the neoclassical model is valid for the description of the radial particle transport and the formation of E r . In general good consistency is found, even for the outer radii where the neoclassical fluxes become much smaller than the experimental ones. In this paper the interplay between the particular E r roots and transport is considered. For strongly positive E r a reduction of χ e is observed in the vicinity of the magnetic axis. The typically negative ion-root in the gradient region strongly influences the local ∇ T i , thus determining the maximum attainable T i (0). (author)

  8. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Tseng, Chiao-Yuan

    2018-01-01

    In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO2 gate insulator and CF4 plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO2 gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm2/V∙s (without treatment) to 54.6 cm2/V∙s (with CF4 plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO2 gate dielectric has also been improved by the CF4 plasma treatment. By applying the CF4 plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device’s immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF4 plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO2 gate dielectric, but also enhances the device’s reliability. PMID:29772767

  9. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2018-05-01

    Full Text Available In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs with a HfO2 gate insulator and CF4 plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO2 gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm2/V∙s (without treatment to 54.6 cm2/V∙s (with CF4 plasma treatment, which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO2 gate dielectric has also been improved by the CF4 plasma treatment. By applying the CF4 plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device’s immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF4 plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO2 gate dielectric, but also enhances the device’s reliability.

  10. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO₂ Gate Dielectrics by CF₄ Plasma Treatment.

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Tseng, Chiao-Yuan

    2018-05-17

    In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO₂ gate insulator and CF₄ plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO₂ gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm²/V∙s (without treatment) to 54.6 cm²/V∙s (with CF₄ plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO₂ gate dielectric has also been improved by the CF₄ plasma treatment. By applying the CF₄ plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device's immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF₄ plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO₂ gate dielectric, but also enhances the device's reliability.

  11. Effects of plasma-induced defects on electrical characteristics of AlGaN/GaN heterostructure before and after low-temperature annealing

    International Nuclear Information System (INIS)

    Takimoto, Takuma; Takeshita, Koji; Nakamura, Seiji; Okumura, Tsugunori

    2014-01-01

    We investigated the electrical characteristics of an AlGaN/GaN heterostructure exposed to Ar plasma. In the near-surface region of the AlGaN/GaN heterostructure, we found that plasma-induced defects reduced the two-dimensional electron gas (2DEG) density and mobility at the AlGaN/GaN interface with increasing exposure time. The decrease in 2DEG density suggests that plasma-induced disordering partly extinguishes the piezo-polarization of the AlGaN layer, that the effective Schottky barrier height is increased by the introduction of negatively changed defects, or that the negatively charged defects induced during plasma exposure deactivate or compensate Si donors. In addition, we investigated the postannealing behavior of plasma-induced defects in the AlGaN/GaN heterostructure as well as in the n-GaN layer under an applied bias voltage. - Highlights: • We have investigated the electrical characteristics of the AlGaN/GaN heterostructure. • Electrons under the AlGaN/GaN interface are decreased by plasma exposure. • Post-annealing treatment with gate bias recovers the degradation caused by defects

  12. Transfer functions of laminar premixed flames subjected to forcing by acoustic waves, AC electric fields, and non-thermal plasma discharges

    KAUST Repository

    Lacoste, Deanna; Xiong, Yuan; Moeck, Jonas P.; Chung, Suk-Ho; Roberts, William L.; Cha, Min

    2016-01-01

    The responses of laminar methane-air flames to forcing by acoustic waves, AC electric fields, and nanosecond repetitively pulsed (NRP) glow discharges are reported here. The experimental setup consists of an axisymmetric burner with a nozzle made from a quartz tube. Three different flame geometries have been studied: conical, M-shaped and V-shaped flames. A central stainless steel rod is used as a cathode for the electric field and plasma excitations. The acoustic forcing is obtained with a loudspeaker located at the bottom part of the burner. For forcing by AC electric fields, a metallic grid is placed above the rod and connected to an AC power supply. Plasma forcing is obtained by applying high-voltage pulses of 10-ns duration applied at 10 kHz, between the rod and an annular stainless steel ring, placed at the outlet of the quartz tube. The chemiluminescence of CH is used to determine the heat release rate fluctuations. For forcing by acoustic waves and plasma, the geometry of the flame plays a key role in the response of the combustion, while the flame shape does not affect the response of the combustion to electric field forcing. The flame response to acoustic forcing of about 10% of the incoming flow is similar to those obtained in the literature. The flames are found to be responsive to an AC electric field across the whole range of frequencies studied. A forcing mechanism, based on the generation of ionic wind, is proposed. The gain of the transfer function obtained for plasma forcing is found to be up to 5 times higher than for acoustic forcing. A possible mechanism of plasma forcing is introduced.

  13. Transfer functions of laminar premixed flames subjected to forcing by acoustic waves, AC electric fields, and non-thermal plasma discharges

    KAUST Repository

    Lacoste, Deanna

    2016-06-23

    The responses of laminar methane-air flames to forcing by acoustic waves, AC electric fields, and nanosecond repetitively pulsed (NRP) glow discharges are reported here. The experimental setup consists of an axisymmetric burner with a nozzle made from a quartz tube. Three different flame geometries have been studied: conical, M-shaped and V-shaped flames. A central stainless steel rod is used as a cathode for the electric field and plasma excitations. The acoustic forcing is obtained with a loudspeaker located at the bottom part of the burner. For forcing by AC electric fields, a metallic grid is placed above the rod and connected to an AC power supply. Plasma forcing is obtained by applying high-voltage pulses of 10-ns duration applied at 10 kHz, between the rod and an annular stainless steel ring, placed at the outlet of the quartz tube. The chemiluminescence of CH is used to determine the heat release rate fluctuations. For forcing by acoustic waves and plasma, the geometry of the flame plays a key role in the response of the combustion, while the flame shape does not affect the response of the combustion to electric field forcing. The flame response to acoustic forcing of about 10% of the incoming flow is similar to those obtained in the literature. The flames are found to be responsive to an AC electric field across the whole range of frequencies studied. A forcing mechanism, based on the generation of ionic wind, is proposed. The gain of the transfer function obtained for plasma forcing is found to be up to 5 times higher than for acoustic forcing. A possible mechanism of plasma forcing is introduced.

  14. Electric field in a plasma channel in a high-pressure nanosecond discharge in hydrogen: a coherent anti-stokes Raman scattering study.

    Science.gov (United States)

    Yatom, S; Tskhai, S; Krasik, Ya E

    2013-12-20

    Experimental results of a study of the electric field in a plasma channel produced during nanosecond discharge at a H2 gas pressure of (2-3)×10(5)  Pa by the coherent anti-Stokes scattering method are reported. The discharge was ignited by applying a voltage pulse with an amplitude of ∼100  kV and a duration of ∼5  ns to a blade cathode placed at a distance of 10 and 20 mm from the anode. It was shown that this type of gas discharge is characterized by the presence of an electric field in the plasma channel with root-mean-square intensities of up to 30  kV/cm. Using polarization measurements, it was found that the direction of the electric field is along the cathode-anode axis.

  15. Controlling the electrical properties of ZnO films by forming zinc and oxide bridges by a plasma and electron-assisted process

    Directory of Open Access Journals (Sweden)

    Norihiro Shimoi

    2012-06-01

    Full Text Available A new method to produce electrically steady ZnO films without any heating process has been developed by using plasma and electron beams to facilitate bonding between the metallic component and the oxygen on coated ZnO films. Both plasma atmosphere and electron beams can function as sources of nonequilibrium bonding energy, forming bridges between the zinc present in the zinc complex and the oxygen in the ZnO particles to construct a zinc-oxide thin film. Our results confirm that it is possible to achieve low conductive characteristics by controlling the acceleration voltage of electrons used to irradiate the ZnO coating. The electrically steady films fabricated have various potential applications, being particularly well-suited to electrical devices on a plastic medium.

  16. Controlling the electrical properties of ZnO films by forming zinc and oxide bridges by a plasma and electron-assisted process

    Energy Technology Data Exchange (ETDEWEB)

    Shimoi, Norihiro; Tanaka, Yasumitsu [Graduate School of Environmental Studies, Tohoku University, 6-6-20 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Harada, Takamitsu [Sendai Technology Center, Consumer-Professional and Devices Group, Sony Corporation, 3-4-1 Sakuragi, Tagajo 985-0842 (Japan); Tanaka, Shun-ichiro [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2012-06-15

    A new method to produce electrically steady ZnO films without any heating process has been developed by using plasma and electron beams to facilitate bonding between the metallic component and the oxygen on coated ZnO films. Both plasma atmosphere and electron beams can function as sources of nonequilibrium bonding energy, forming bridges between the zinc present in the zinc complex and the oxygen in the ZnO particles to construct a zinc-oxide thin film. Our results confirm that it is possible to achieve low conductive characteristics by controlling the acceleration voltage of electrons used to irradiate the ZnO coating. The electrically steady films fabricated have various potential applications, being particularly well-suited to electrical devices on a plastic medium.

  17. Economic analysis of self-generated plutonium recycling in light water reactor

    International Nuclear Information System (INIS)

    Deguchi, Morimoto; Hirabayashi, Fumio; Yumoto, Ryozo

    1978-01-01

    This paper describes on the economics of plutonium recycle to light water reactors (LWRs). In the situation that plutonium market does not exist, it is realistic for utilities to recycle the self-generated plutonium to their own reactors. The economic incentive to recycle self-generated plutonium, plutonium fuel fabrication penalty, and the dependence of fuel cycle cost on fuel cycle cost parameters are considered. In recycling self-generated plutonium, two alternatives for fuel element design are feasible. Those are the all-plutonium design and the island design. In the present analysis, the all-plutonium design was chosen for PWRs. The calculation of reactivity variation along with burnup for both uranium fuel and plutonium fuel was done with LASER-PNC code. Plutonium inventory and other nuclear data were calculated with CHAIN code. It is expected that equilibrium composition is reached after 5 or 6 times of recycling. For the calculation of fuel cycle cost, MITCOST code was used. The recent increase in the prices of uranium ore, enrichment and reprocessing services was taken into account. The fuel cycle cost of plutonium recycle is lower than that of uranium fuel cycle within a certain limit of plutonium fabrication penalty. It is shown that the fabrication penalty of about 1250 dollar/kgHM for each plutonium successive recycle reduces the cost difference to zero. The change in other cost components affects break-even fabrication penalty, in which the fuel cycle cost of plutonium recycle is equal to that of uranium cycle. (Kato, T.)

  18. [Impacts of the low-frequency electric stimulation at the acupoints on the content of plasma 5-HT and NE in the patients with post-stroke insomnia].

    Science.gov (United States)

    Tang, Lei; Ma, Chaoyan; You, Fei; Ding, Lin

    2015-08-01

    To compare the clinical efficacy on post-stroke insomnia between the low-frequency electric stimulation at the acupoints and the conventional western medication in the patients so as to explore the effect mechanism. One hundred and twenty patients of post-stroke insomnia were randomized into a low-frequency electric stimulation group, a medication group and a placebo group, 40 cases in each one. In the low-frequency electric stimulation group, the low-frequency pulse electric apparatus was applied to stimulate Dazhui (GV 14) and Shenshu (BL 23), once every day. The treatment for 15 days made one session and 2 sessions were required. In the medication group, estazolam was taken orally, 1 mg each time; and in the placebo group, the starch capsules were taken, one capsule each time; in the two groups the treatment was adopted before sleep every night, continuously for 15 days as one session, and 2 sessions were required. The levels of plasma 5-hydroxytryptamine (5-HT) and norepinephrine (NE) were compared before and after treatment in the patients of the three groups and: the efficacy was compared. In the placebo group, 1 case was dropped out. The total effective rate was 95. 0% (38/40), 92. 5% (37/40) and 17. 9% (7/39) in the low-frequency electric stimulation group, the medication group and the placebo group respectively. The effects in the low-frequency electric stimulation group and the medication group were better apparently than that in the placebo group (both Plow-frequency electric stimulation group and the medication group (P>0. 05). The levels of plasma 5-HT and NE were not different significantly between before and after treatment in the placebo group. The level of plasma 5-HT was increased (both Plow-frequency electric stimulation group and the medication group. But the differences were not significant between the two groups (P>0. 05). The low-frequency electric stimlaton a the acupoints is safe and effective in the treatment of post-stroke insomnia, which

  19. A fundamental self-generated quenching center for lanthanide-doped high-purity solids

    International Nuclear Information System (INIS)

    Auzel, F.

    2002-01-01

    An intrinsic self-generated quenching center for lanthanide-doped high-purity solids is presented for transitions, which cannot be quenched by cross-relaxation. This center, in fact a cluster-like pair of active centers, is shown to come from a particular multiphonon-assisted energy transfer between them. Being due to the vibronic properties of the host it cannot be suppressed. Its role in lanthanide first excited states self-quenching is analyzed and a simple mathematical expression is derived. This law is compared with experimental results for self-quenching in Er-doped fluorophosphate glasses

  20. Self-generation and management of spin-electromagnetic wave solitons and chaos

    International Nuclear Information System (INIS)

    Ustinov, Alexey B.; Kondrashov, Alexandr V.; Nikitin, Andrey A.; Kalinikos, Boris A.

    2014-01-01

    Self-generation of microwave spin-electromagnetic wave envelope solitons and chaos has been observed and studied. For the investigation, we used a feedback active ring oscillator based on artificial multiferroic, which served as a nonlinear waveguide. We show that by increasing the wave amplification in the feedback ring circuit, a transition from monochromatic auto-generation to soliton train waveform and then to dynamical chaos occurs in accordance with the Ruelle-Takens scenario. Management of spin-electromagnetic-wave solitons and chaos parameters by both dielectric permittivity and magnetic permeability of the multiferroic waveguiding structure is demonstrated.

  1. Plasma-based determination of inorganic contaminants in waste of electric and electronic equipment after microwave-induced combustion

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Paola A.; Diehl, Lisarb O.; Oliveira, Jussiane S.S.; Muller, Edson I. [Departamento de Química, Universidade Federal de Santa Maria, Av. Roraima, 1000, 97105-900, Santa Maria (Brazil); Mesko, Marcia F. [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, 96900-010 Pelotas, RS (Brazil); Flores, Erico M.M., E-mail: ericommf@gmail.com [Departamento de Química, Universidade Federal de Santa Maria, Av. Roraima, 1000, 97105-900, Santa Maria (Brazil)

    2015-03-01

    A systematic study was performed for the determination of inorganic contaminants in polymeric waste from electrical and electronic equipment (EEE) for achieving an efficient digestion to minimize interferences in determination using plasma-based techniques. The determination of As, Br, Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn by inductively coupled plasma mass spectrometry (ICP-MS) and also by inductively coupled plasma optical emission spectrometry (ICP OES) was carried out after digestion using microwave-induced combustion (MIC). Arsenic and Hg were determined by flow-injection chemical vapor generation inductively coupled plasma mass spectrometry (FI-CVG-ICP-MS). Dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) with ammonia was also used for Cr determination. The suitability of MIC for digestion of sample masses up to 400 mg was demonstrated using microcrystalline cellulose as aid for combustion of polymers from waste of EEEs that usually contain flame retardants that impair the combustion. The composition and concentration of acid solutions (HNO{sub 3} or HNO{sub 3} plus HCl) were evaluated for metals and metalloids and NH{sub 4}OH solutions were investigated for Br absorption. Accuracy was evaluated by comparison of results with those obtained using high pressure microwave-assisted wet digestion (HP-MAWD) and also by the analysis of certified reference material (CRM) of polymer (EC680k—low-density polyethylene). Bromine determination was only feasible using digestion by MIC once losses were observed when HP-MAWD was used. Lower limits of detection were obtained for all analytes using MIC (from 0.005 μg g{sup −1} for Co by ICP-MS up to 3.120 μg g{sup −1} for Sb by ICP OES) in comparison to HP-MAWD due to the higher sample mass that can be digested (400 mg) and the use of diluted absorbing solutions. The combination of HNO{sub 3} and HCl for digestion showed to be crucial for quantitative recovery of some elements, as Cr and Sb

  2. A practical nonlocal model for heat transport in magnetized laser plasmas

    International Nuclear Information System (INIS)

    Nicolaie, Ph.D.; Feugeas, J.-L.A.; Schurtz, G.P.

    2006-01-01

    A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaie, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case

  3. A practical nonlocal model for heat transport in magnetized laser plasmas

    Science.gov (United States)

    Nicolaï, Ph. D.; Feugeas, J.-L. A.; Schurtz, G. P.

    2006-03-01

    A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaï, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case.

  4. Measurement of the Electrical Conductivity of He3 Plasma Induced by Neutron Irradiation

    International Nuclear Information System (INIS)

    Braun, J.; Nygaard, K.

    1966-03-01

    The conductivity of a He plasma created by the inelastic reaction with thermal neutrons: 3 He + n th -> 3 H + p + 0.76 MeV is studied as a function of neutron flux, gas temperature and gas density. Using reported values of the electron mobility the electron density is calculated from experimental conductivity values. Further, by accepting a reasonable value for the mean energy lost in creating one ion-pair, the recombination coefficient is estimated. The measurements performed so far cover temperatures between 300 - 1600 K and densities between 0.25 - 1 times the density at atmospheric pressure and 300 K. The neutron flux is varied between 10 10 - 10 11 n/cm 2 /s. As a sample of results achieved at 1600 K and the lowest density (corresponding to about atmospheric pressure) and the highest neutron flux the following values are obtained for the conductivity, the electron density and the recombination coefficient respectively: σ 0.2 S/m, n e 6x10 11 /cm 3 , α = 2xl0 -10 cm 3 /s. An extrapolation of data obtained shows that the concept of neutron induced conductivity should be attractive for MHD power generation

  5. Electrical characterization of deep levels in n-type GaAs after hydrogen plasma treatment

    International Nuclear Information System (INIS)

    Nyamhere, C.; Botha, J.R.; Venter, A.

    2011-01-01

    Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20-300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, E C -0.33 eV, E C -0.36 eV, E C -0.38 eV and E C -0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at E C -0.58 eV. Isochronal annealing of the passivated material between 50 and 300 o C, revealed the emergence of a secondary defect, not previously observed, at E C -0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 o C, as all the defects originally observed in the reference sample were recovered.

  6. Electrical characterization of deep levels in n-type GaAs after hydrogen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nyamhere, C., E-mail: s210239522@live.nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Botha, J.R.; Venter, A. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2011-05-15

    Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20-300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, E{sub C}-0.33 eV, E{sub C}-0.36 eV, E{sub C}-0.38 eV and E{sub C}-0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at E{sub C}-0.58 eV. Isochronal annealing of the passivated material between 50 and 300 {sup o}C, revealed the emergence of a secondary defect, not previously observed, at E{sub C}-0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 {sup o}C, as all the defects originally observed in the reference sample were recovered.

  7. Measurement of the Electrical Conductivity of He{sup 3} Plasma Induced by Neutron Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Braun, J; Nygaard, K

    1966-03-15

    The conductivity of a He plasma created by the inelastic reaction with thermal neutrons: {sup 3}He + n{sub th} -> {sup 3}H + p + 0.76 MeV is studied as a function of neutron flux, gas temperature and gas density. Using reported values of the electron mobility the electron density is calculated from experimental conductivity values. Further, by accepting a reasonable value for the mean energy lost in creating one ion-pair, the recombination coefficient is estimated. The measurements performed so far cover temperatures between 300 - 1600 K and densities between 0.25 - 1 times the density at atmospheric pressure and 300 K. The neutron flux is varied between 10{sup 10} - 10{sup 11} n/cm{sup 2}/s. As a sample of results achieved at 1600 K and the lowest density (corresponding to about atmospheric pressure) and the highest neutron flux the following values are obtained for the conductivity, the electron density and the recombination coefficient respectively: {sigma} 0.2 S/m, n{sub e} 6x10{sup 11}/cm{sup 3}, {alpha} = 2xl0{sup -10} cm{sup 3}/s. An extrapolation of data obtained shows that the concept of neutron induced conductivity should be attractive for MHD power generation.

  8. Effect of electrical stunning frequency on meat quality, plasma parameters, and protein solubility of broilers.

    Science.gov (United States)

    Huang, J C; Yang, J; Zhang, B H; Huang, M; Chen, K J; Xu, X L; Zhou, G H

    2017-08-01

    This study was designed to compare the effects of different stunning frequencies of pulsed direct current on meat quality of broilers. This was achieved by investigating plasma parameters, blood loss, carcass damage, meat water-holding capacity, meat color, meat shear value, muscle pH, and protein solubility. A total of 400 broilers was divided into 5 treatment groups and stunned with 500, 600, 700, 800, and 900 Hz at 15 V for 10 seconds. Blood samples were collected immediately after cutting the neck. Pectoralis major muscles were removed from the carcass after chilling and placed in ice. Breast muscle pH and meat color were determined at both 2 and 24 h postmortem. Drip loss, cooking loss, pressing loss, and cooked breast meat-shear values were determined at 24 h postmortem. Treatment at 500 and 900 Hz significantly increased (P meat color were not affected by stunning frequency. In the 500 and 900 Hz groups, the protein solubility and shear force values were significantly lower (P < 0.05) and drip loss was significantly higher (P < 0.05) than in the 700 Hz group. This study indicates that the waveform of the pulsed direct current is acceptable for stunning broilers at a stunning frequency of 700 Hz. © 2017 Poultry Science Association Inc.

  9. Application of the self-generation effect to the learning of Blissymbols by persons presenting with a severe aphasia.

    Science.gov (United States)

    Rajaram, Priya; Alant, Erna; Dada, Shakila

    2012-06-01

    This study investigated the application of the self-generation effect to enhance the recognition and retention of Blissymbols in persons with severe aphasia. A 2×2×3 factorial design of two treatment types (self-generation and non-generation) was used to teach two sets of Blissymbols. These were administered during 3 training days, between which were withdrawal periods of 1 day and 7 days. Recognition and retention probes were administered at intervals during the training. ANOVA analysis showed that the self-generation treatment produced no immediate recognition advantage; however, better retention of symbol recognition may have occurred over time. Hence, the potential application of the self-generation effect in enhancing the retention of Blissymbols in persons with severe aphasia may warrant further investigation.

  10. Platelet-rich plasma stimulated by pulse electric fields: Platelet activation, procoagulant markers, growth factor release and cell proliferation.

    Science.gov (United States)

    Frelinger, A L; Torres, A S; Caiafa, A; Morton, C A; Berny-Lang, M A; Gerrits, A J; Carmichael, S L; Neculaes, V B; Michelson, A D

    2016-01-01

    Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.

  11. Ion acceleration in non-equilibrium plasmas driven by fast drifting electron

    Energy Technology Data Exchange (ETDEWEB)

    Castro, G. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Di Bartolo, F., E-mail: fdibartolo@unime.it [Università di Messina, V.le F. Stagno D’Alcontres 31, 98166, Messina (Italy); Gambino, N. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Metodologie Fisiche e Chimiche per L’ingegneria, Viale A.Doria 6, 95125 Catania (Italy); Mascali, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Romano, F.P. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CNR-IBAM Via Biblioteca 4, 95124 Catania (Italy); Anzalone, A.; Celona, L.; Gammino, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Di Giugno, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Lanaia, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Miracoli, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Serafino, T. [CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Tudisco, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy)

    2013-05-01

    We hereby present results on ion acceleration mechanisms in non equilibrium plasmas generated by microwaves or high intensity laser pulses. Experiments point out that in magnetized plasmas X–B conversion takes place for under resonance values of the magnetic field, i.e. an electromagnetic mode is converted into an electrostatic wave. The strong self-generated electric field, of the order of 10{sup 7} V/m, causes a E × B drift which accelerates both ions and electrons, as it is evident by localized sputtering in the plasma chamber. These fields are similar (in magnitude) to the ones obtainable in laser generated plasmas at intensity of 10{sup 12} W/cm{sup 2}. In this latter case, we observe that the acceleration mechanism is driven by electrons drifting much faster than plasma bulk, thus generating an extremely strong electric field ∼10{sup 7} V/m. The two experiments confirm that ions acceleration at low energy is possible with table-top devices and following complementary techniques: i.e. by using microwave-driven (producing CW beams) plasmas, or non-equilibrium laser-driven plasmas (producing pulsed beams). Possible applications involve ion implantation, materials surface modifications, ion beam assisted lithography, etc.

  12. Brain mechanisms associated with internally directed attention and self-generated thought.

    Science.gov (United States)

    Benedek, Mathias; Jauk, Emanuel; Beaty, Roger E; Fink, Andreas; Koschutnig, Karl; Neubauer, Aljoscha C

    2016-03-10

    Internal cognition like imagination and prospection require sustained internally directed attention and involve self-generated thought. This fMRI study aimed to disentangle the brain mechanisms associated with attention-specific and task-specific processes during internally directed cognition. The direction of attention was manipulated by either keeping a relevant stimulus visible throughout the task, or by masking it, so that the task had to be performed "in the mind's eye". The level of self-directed thought was additionally varied between a convergent and a divergent thinking task. Internally directed attention was associated with increased activation in the right anterior inferior parietal lobe (aIPL), bilateral lingual gyrus and the cuneus, as well as with extended deactivations of superior parietal and occipital regions representing parts of the dorsal attention network. The right aIPL further showed increased connectivity with occipital regions suggesting an active top-down mechanism for shielding ongoing internal processes from potentially distracting sensory stimulation in terms of perceptual decoupling. Activation of the default network was not related to internally directed attention per se, but rather to a higher level of self-generated thought. The findings hence shed further light on the roles of inferior and superior parietal cortex for internally directed cognition.

  13. Radially and temporally resolved electric field of positive streamers in air and modelling of the induced plasma chemistry

    Science.gov (United States)

    Hoder, T.; Šimek, M.; Bonaventura, Z.; Prukner, V.; Gordillo-Vázquez, F. J.

    2016-08-01

    The initial stages of transient luminous events (TLEs) occurring in the upper atmosphere of the Earth are, in a certain pressure range, controlled by the streamer mechanism. This paper presents the results of the first laboratory experiments to study the TLE streamer phenomena under conditions close to those of the upper atmosphere. Spectrally and highly spatiotemporally resolved emissions originating from radiative states {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) (second positive system) and \\text{N}2+≤ft({{\\text{B}}2}Σu+\\right) (first negative system) have been recorded from the positive streamer discharge. Periodic ionizing events were generated in a barrier discharge arrangement at a pressure of 4 torr of synthetic air, i.e. simulating the pressure conditions at altitudes of ≃37 km. Employing Abel inversion on the radially scanned streamer emission and a 2D fitting procedure, access was obtained to the local spectral signatures within the over 106  m s-1 fast propagating streamers. The reduced electric field strength distribution within the streamer head was determined from the ratio of the \\text{N}2+/{{\\text{N}}2} band intensities with peak values up to 500 Td and overall duration of about 10 ns. The 2D profiles of the streamer head electric fields were used as an experimentally obtained input for kinetic simulations of the streamer-induced air plasma chemistry. The radial and temporal computed distribution of the ground vibrational levels of the radiative states involved in the radiative transitions analyzed (337.1 nm and 391.5 nm), atomic oxygen, nitrogen, nitric oxide and ozone concentrations are vizualized and discussed in comparison with available models of the streamer phase of Blue Jet discharges in the stratosphere.

  14. Plasma Nitriding of AISI 304 Stainless Steel in Cathodic and Floating Electric Potential: Influence on Morphology, Chemical Characteristics and Tribological Behavior

    Science.gov (United States)

    Li, Yang; He, Yongyong; Wang, Wei; Mao, Junyuan; Zhang, Lei; Zhu, Yijie; Ye, Qianwen

    2018-03-01

    In direct current plasma nitriding (DCPN), the treated components are subjected to a high cathodic potential, which brings several inherent shortcomings, e.g., damage by arcing and the edging effect. In active screen plasma nitriding (ASPN) processes, the cathodic potential is applied to a metal screen that surrounds the workload, and the component to be treated is placed in a floating potential. Such an electrical configuration allows plasma to be formed on the metal screen surface rather than on the component surface; thus, the shortcomings of the DCPN are eliminated. In this work, the nitrided experiments were performed using a plasma nitriding unit. Two groups of samples were placed on the table in the cathodic and the floating potential, corresponding to the DCPN and ASPN, respectively. The floating samples and table were surrounded by a steel screen. The DCPN and ASPN of the AISI 304 stainless steels are investigated as a function of the electric potential. The samples were characterized using scanning electron microscopy with energy-dispersive x-ray spectroscopy, x-ray diffraction, atomic force microscopy and transmission electron microscope. Dry sliding ball-on-disk wear tests were conducted on the untreated substrate, DCPN and ASPN samples. The results reveal that all nitrided samples successfully produced similar nitrogen-supersaturated S phase layers on their surfaces. This finding also shows the strong impact of the electric potential of the nitriding process on the morphology, chemical characteristics, hardness and tribological behavior of the DCPN and ASPN samples.

  15. Plasma parameters of the cathode spot explosive electron emission cell obtained from the model of liquid-metal jet tearing and electrical explosion

    Science.gov (United States)

    Tsventoukh, M. M.

    2018-05-01

    A model has been developed for the explosive electron emission cell pulse of a vacuum discharge cathode spot that describes the ignition and extinction of the explosive pulse. The pulse is initiated due to hydrodynamic tearing of a liquid-metal jet which propagates from the preceding cell crater boundary and draws the ion current from the plasma produced by the preceding explosion. Once the jet neck has been resistively heated to a critical temperature (˜1 eV), the plasma starts expanding and decreasing in density, which corresponds to the extinction phase. Numerical and analytical solutions have been obtained that describe both the time behavior of the pulse plasma parameters and their average values. For the cell plasma, the momentum per transferred charge has been estimated to be some tens of g cm/(s C), which is consistent with the known measurements of ion velocity, ion erosion rate, and specific recoil force. This supports the model of the pressure-gradient-driven plasma acceleration mechanism for the explosive cathode spot cells. The ohmic electric field within the explosive current-carrying plasma has been estimated to be some tens of kV/cm, which is consistent with the known experimental data on cathode potential fall and explosive cell plasma size. This supports the model that assumes the ohmic nature of the cathode potential fall in a vacuum discharge.

  16. Amplification due to two-stream instability of self-electric and magnetic fields of an ion beam propagating in background plasma

    Science.gov (United States)

    Tokluoglu, Erinc K.; Kaganovich, Igor D.; Carlsson, Johan A.; Hara, Kentaro; Startsev, Edward A.

    2018-05-01

    Propagation of charged particle beams in background plasma as a method of space charge neutralization has been shown to achieve a high degree of charge and current neutralization and therefore enables nearly ballistic propagation and focusing of charged particle beams. Correspondingly, the use of plasmas for propagation of charged particle beams has important applications for transport and focusing of intense particle beams in inertial fusion and high energy density laboratory plasma physics. However, the streaming of beam ions through a background plasma can lead to the development of two-stream instability between the beam ions and the plasma electrons. The beam electric and magnetic fields enhanced by the two-stream instability can lead to defocusing of the ion beam. Using particle-in-cell simulations, we study the scaling of the instability-driven self-electromagnetic fields and consequent defocusing forces with the background plasma density and beam ion mass. We identify plasma parameters where the defocusing forces can be reduced.

  17. FORMATION OF THE INITIAL DISTRIBUTION OF PLASMA COMPONENTS ON THE PHASE PLANE OF LARGE PARTICLES METHOD IN ELECTRIC ARC SYNTHESIS CNS

    Directory of Open Access Journals (Sweden)

    G. V. Abramov

    2014-01-01

    Full Text Available The article deals with the modeling of charged particles in a multicomponent plasma of electric arc discharge with binary collisions in the synthesis of carbon nanostructures (CNS. One of the common methods of obtaining the quality of fullerenes and nanotubes is arc synthesis under inert gas (helium. The determination of the necessary conditions and the mechanism of formation of carbon clusters in the plasma forming set CNS will more effectively and efficiently manage this process. Feature of the problem is that in a plasma arc discharge is a large number of particle interactions and on the cathode surface. Due to the high temperatures and high energy concentration in plasma detailed experimental investigation difficult to carry out. With the aim of avoiding difficult and costly physical experiments developed numerical methods for the analysis of plasma processes. In this article to solve a system of equations of Maxwell - Boltzmann basis for the authors had taken the method of large particles, which reduces the amount of computation and reduce the demands on computing resources. The authors cites the general design scheme of the large particles, and the algorithm of particle distribution of a multicomponent plasma in the phase plane at the initial time. In conclusion, the author argues that the results in the future will define the zone satisfies the energy conditions, the probability of formation of a plasma cluster groups of carbon involved in the synthesis of the CNS.

  18. A study of plasma facing tungsten components with electrical discharge machined surface exposed to cyclic thermal loads

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Yohji, E-mail: seki.yohji@jaea.go.jp; Ezato, Koichiro; Suzuki, Satoshi; Yokoyama, Kenji; Yamada, Hirokazu; Hirayama, Tomoyuki

    2016-11-01

    Through R&D for a plasma facing units (PFUs) in an outer vertical target of an ITER full-tungsten (W) divertor, Japan Atomic Energy Agency succeeded in demonstrating the durability of the W divertor shaped by an electrical discharge machining (EDM). To prevent melting of W armors in the PFUs, an adequate technology to meet requirements of a geometrical shape and a tolerance is one of the most important key issues in a manufacturing process. From the necessity, the EDM has been evaluated to control the final shape of the W armor. Though the EDM was known to be advantages such as an easy workability, a potential disadvantage of presence of micro-cracks on the W surface appeared. In order to examine a potential effect of the micro-crack on a heat removal durability, a high heat flux testing was carried out for the W divertor mock-up with the polish and the EDM. As the result, all of the W armors endured the repetitive heat load of 1000 cycles at an absorbed heat flux of more than 20 MW/m{sup 2}, which strongly encourages the realization of the PFUs of the ITER full-W divertor with the various geometrical shape and the high accuracy tolerance.

  19. A study of plasma facing tungsten components with electrical discharge machined surface exposed to cyclic thermal loads

    International Nuclear Information System (INIS)

    Seki, Yohji; Ezato, Koichiro; Suzuki, Satoshi; Yokoyama, Kenji; Yamada, Hirokazu; Hirayama, Tomoyuki

    2016-01-01

    Through R&D for a plasma facing units (PFUs) in an outer vertical target of an ITER full-tungsten (W) divertor, Japan Atomic Energy Agency succeeded in demonstrating the durability of the W divertor shaped by an electrical discharge machining (EDM). To prevent melting of W armors in the PFUs, an adequate technology to meet requirements of a geometrical shape and a tolerance is one of the most important key issues in a manufacturing process. From the necessity, the EDM has been evaluated to control the final shape of the W armor. Though the EDM was known to be advantages such as an easy workability, a potential disadvantage of presence of micro-cracks on the W surface appeared. In order to examine a potential effect of the micro-crack on a heat removal durability, a high heat flux testing was carried out for the W divertor mock-up with the polish and the EDM. As the result, all of the W armors endured the repetitive heat load of 1000 cycles at an absorbed heat flux of more than 20 MW/m"2, which strongly encourages the realization of the PFUs of the ITER full-W divertor with the various geometrical shape and the high accuracy tolerance.

  20. Nanosecond pulsed electric field (nsPEF) enhance cytotoxicity of cisplatin to hepatocellular cells by microdomain disruption on plasma membrane.

    Science.gov (United States)

    Yin, Shengyong; Chen, Xinhua; Xie, Haiyang; Zhou, Lin; Guo, Danjing; Xu, Yuning; Wu, Liming; Zheng, Shusen

    2016-08-15

    Previous studies showed nanosecond pulsed electric field (nsPEF) can ablate solid tumors including hepatocellular carcinoma (HCC) but its effect on cell membrane is not fully understood. We hypothesized nsPEF disrupt the microdomains on outer-cellular membrane with direct mechanical force and as a result the plasma membrane permeability increases to facilitate the small molecule intake. Three HCC cells were pulsed one pulse per minute, an interval longer than nanopore resealing time. The cationized ferritin was used to mark up the electronegative microdomains, propidium iodide (PI) for membrane permeabilization, energy dispersive X-ray spectroscopy (EDS) for the negative cell surface charge and cisplatin for inner-cellular cytotoxicity. We demonstrated that the ferritin marked-microdomain and negative cell surface charge were disrupted by nsPEF caused-mechanical force. The cell uptake of propidium and cytotoxicity of DNA-targeted cisplatin increased with a dose effect. Cisplatin gains its maximum inner-cellular cytotoxicity when combining with nsPEF stimulation. We conclude that nsPEF disrupt the microdomains on the outer cellular membrane directly and increase the membrane permeabilization for PI and cisplatin. The microdomain disruption and membrane infiltration changes are caused by the mechanical force from the changes of negative cell surface charge. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Energy band structure and electrical properties of Ga-oxide/GaN interface formed by remote oxygen plasma

    Science.gov (United States)

    Yamamoto, Taishi; Taoka, Noriyuki; Ohta, Akio; Truyen, Nguyen Xuan; Yamada, Hisashi; Takahashi, Tokio; Ikeda, Mitsuhisa; Makihara, Katsunori; Nakatsuka, Osamu; Shimizu, Mitsuaki; Miyazaki, Seiichi

    2018-06-01

    The energy band structure of a Ga-oxide/GaN structure formed by remote oxygen plasma exposure and the electrical interface properties of the GaN metal–oxide–semiconductor (MOS) capacitors with the SiO2/Ga-oxide/GaN structures with postdeposition annealing (PDA) at various temperatures have been investigated. Reflection high-energy electron diffraction and X-ray photoelectron spectroscopy clarified that the formed Ga-oxide layer is neither a single nor polycrystalline phase with high crystallinity. We found that the energy band offsets at the conduction band minimum and at the valence band maximum between the Ga-oxide layer and the GaN surface were 0.4 and 1.2 ± 0.2 eV, respectively. Furthermore, capacitance–voltage (C–V) characteristics revealed that the interface trap density (D it) is lower than the evaluation limit of Terman method without depending on the PDA temperatures, and that the SiO2/Ga-oxide stack can work as a protection layer to maintain the low D it, avoiding the significant decomposition of GaN at the high PDA temperature of 800 °C.

  2. Nanosecond pulsed electric field (nsPEF) enhance cytotoxicity of cisplatin to hepatocellular cells by microdomain disruption on plasma membrane

    International Nuclear Information System (INIS)

    Yin, Shengyong; Chen, Xinhua; Xie, Haiyang; Zhou, Lin; Guo, Danjing; Xu, Yuning; Wu, Liming; Zheng, Shusen

    2016-01-01

    Previous studies showed nanosecond pulsed electric field (nsPEF) can ablate solid tumors including hepatocellular carcinoma (HCC) but its effect on cell membrane is not fully understood. We hypothesized nsPEF disrupt the microdomains on outer-cellular membrane with direct mechanical force and as a result the plasma membrane permeability increases to facilitate the small molecule intake. Three HCC cells were pulsed one pulse per minute, an interval longer than nanopore resealing time. The cationized ferritin was used to mark up the electronegative microdomains, propidium iodide (PI) for membrane permeabilization, energy dispersive X-ray spectroscopy (EDS) for the negative cell surface charge and cisplatin for inner-cellular cytotoxicity. We demonstrated that the ferritin marked-microdomain and negative cell surface charge were disrupted by nsPEF caused-mechanical force. The cell uptake of propidium and cytotoxicity of DNA-targeted cisplatin increased with a dose effect. Cisplatin gains its maximum inner-cellular cytotoxicity when combining with nsPEF stimulation. We conclude that nsPEF disrupt the microdomains on the outer cellular membrane directly and increase the membrane permeabilization for PI and cisplatin. The microdomain disruption and membrane infiltration changes are caused by the mechanical force from the changes of negative cell surface charge.

  3. Nanosecond pulsed electric field (nsPEF) enhance cytotoxicity of cisplatin to hepatocellular cells by microdomain disruption on plasma membrane

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Shengyong; Chen, Xinhua; Xie, Haiyang; Zhou, Lin [Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, 310003 Hangzhou (China); Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health and Key Laboratory of Organ Transplantation of Zhejiang Province, The Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003 (China); Guo, Danjing; Xu, Yuning [Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health and Key Laboratory of Organ Transplantation of Zhejiang Province, The Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003 (China); Wu, Liming, E-mail: wlm@zju.edu.cn [Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, 310003 Hangzhou (China); Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health and Key Laboratory of Organ Transplantation of Zhejiang Province, The Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003 (China); Zheng, Shusen, E-mail: shusenzheng@zju.edu.cn [Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, 310003 Hangzhou (China); Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health and Key Laboratory of Organ Transplantation of Zhejiang Province, The Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, Zhejiang University, Hangzhou 310003 (China)

    2016-08-15

    Previous studies showed nanosecond pulsed electric field (nsPEF) can ablate solid tumors including hepatocellular carcinoma (HCC) but its effect on cell membrane is not fully understood. We hypothesized nsPEF disrupt the microdomains on outer-cellular membrane with direct mechanical force and as a result the plasma membrane permeability increases to facilitate the small molecule intake. Three HCC cells were pulsed one pulse per minute, an interval longer than nanopore resealing time. The cationized ferritin was used to mark up the electronegative microdomains, propidium iodide (PI) for membrane permeabilization, energy dispersive X-ray spectroscopy (EDS) for the negative cell surface charge and cisplatin for inner-cellular cytotoxicity. We demonstrated that the ferritin marked-microdomain and negative cell surface charge were disrupted by nsPEF caused-mechanical force. The cell uptake of propidium and cytotoxicity of DNA-targeted cisplatin increased with a dose effect. Cisplatin gains its maximum inner-cellular cytotoxicity when combining with nsPEF stimulation. We conclude that nsPEF disrupt the microdomains on the outer cellular membrane directly and increase the membrane permeabilization for PI and cisplatin. The microdomain disruption and membrane infiltration changes are caused by the mechanical force from the changes of negative cell surface charge.

  4. Report on the 4th Europhysics Workshop on the role of electric fields in plasma confinement and exhaust (Funchal, Madeira, 24-25 June 2001)

    International Nuclear Information System (INIS)

    Oost, G. van; Tendler, M.

    2002-01-01

    The 4th Europhysics Workshop was organized in Funchal in Madeira as a Satellite Meeting of the 28th EPS Conference on Controlled Fusion and Plasma Physics, and attended by about 45 scientists from 15 countries. It was hosted by the Portuguese Association IST-Euratom, and organized by the Czech Association Euratom/IPP.CR. The scope of the workshop is broad and includes experiments, techniques, theory and modelling pertinent to the effects of electric fields on plasmas. After refereeing, 18 of the 27 (oral) contributions were published in the October 2001 issue of Czechoslovak Journal of Physics. (author)

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

    International Nuclear Information System (INIS)

    Spencer, R.L.

    1990-01-01

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

  6. THE NONLINEAR OHM'S LAW: PLASMA HEATING BY STRONG ELECTRIC FIELDS AND ITS EFFECTS ON THE IONIZATION BALANCE IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Okuzumi, Satoshi [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Inutsuka, Shu-ichiro, E-mail: okuzumi@geo.titech.ac.jp [Department of Physics, Nagoya University, Nagoya, Aichi 464-8602 (Japan)

    2015-02-10

    The ionization state of the gas plays a key role in the magnetohydrodynamics (MHD) of protoplanetary disks. However, the ionization state can depend on the gas dynamics, because electric fields induced by MHD turbulence can heat up plasmas and thereby affect the ionization balance. To study this nonlinear feedback, we construct an ionization model that includes plasma heating by electric fields and impact ionization by heated electrons, as well as charging of dust grains. We show that when plasma sticking onto grains is the dominant recombination process, the electron abundance in the gas decreases with increasing electric field strength. This is a natural consequence of electron-grain collisions whose frequency increases with the electron's random velocity. The decreasing electron abundance may lead to a self-regulation of MHD turbulence. In some cases, not only the electron abundance but also the electric current decreases with increasing field strength in a certain field range. The resulting N-shaped current-field relation violates the fundamental assumption of the non-relativistic MHD that the electric field is uniquely determined by the current density. At even higher field strengths, impact ionization causes an abrupt increase of the electric current as expected by previous studies. We find that this discharge current is multi-valued (i.e., the current-field relation is S-shaped) under some circumstances, and that the intermediate branch is unstable. The N/S-shaped current-field relations may yield hysteresis in the evolution of MHD turbulence in some parts of protoplanetary disks.

  7. Improved plasma accelerator

    Science.gov (United States)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  8. Expansion of plasma of electrically exploding single copper wire under 4.5 kA-9.5 kA/wire

    International Nuclear Information System (INIS)

    Li Yexun; Yang Libing; Sun Chengwei

    2003-01-01

    The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design

  9. The default network and self-generated thought: component processes, dynamic control, and clinical relevance

    Science.gov (United States)

    Andrews-Hanna, Jessica R.; Smallwood, Jonathan; Spreng, R. Nathan

    2014-01-01

    Though only a decade has elapsed since the default network was first emphasized as being a large-scale brain system, recent years have brought great insight into the network’s adaptive functions. A growing theme highlights the default network as playing a key role in internally-directed—or self-generated—thought. Here, we synthesize recent findings from cognitive science, neuroscience, and clinical psychology to focus attention on two emerging topics as current and future directions surrounding the default network. First, we present evidence that self-generated thought is a multi-faceted construct whose component processes are supported by different subsystems within the network. Second, we highlight the dynamic nature of the default network, emphasizing its interaction with executive control systems when regulating aspects of internal thought. We conclude by discussing clinical implications of disruptions to the integrity of the network, and consider disorders when thought content becomes polarized or network interactions become disrupted or imbalanced. PMID:24502540

  10. Scott Correction for Large Atoms and Molecules in a Self-Generated Magnetic Field

    DEFF Research Database (Denmark)

    Erdös, Laszlo; Fournais, Søren; Solovej, Jan Philip

    2012-01-01

    constant. We show that, in the simultaneous limit $Z\\to\\infty$, $\\al\\to 0$ such that $\\kappa =Z\\al^2$ is fixed, the ground state energy of the system is given by a two term expansion $c_1Z^{7/3} + c_2(\\kappa) Z^2 + o(Z^2)$. The leading term is given by the non-magnetic Thomas-Fermi theory. Our result shows......We consider a large neutral molecule with total nuclear charge $Z$ in non-relativistic quantum mechanics with a self-generated classical electromagnetic field. To ensure stability, we assume that $Z\\al^2\\le \\kappa_0$ for a sufficiently small $\\kappa_0$, where $\\al$ denotes the fine structure...... that the magnetic field affects only the second (so-called Scott) term in the expansion....

  11. Gender differences in adolescent smoking: mediator and moderator effects of self-generated expected smoking outcomes.

    Science.gov (United States)

    Vidrine, Jennifer Irvin; Anderson, Cheryl B; Pollak, Kathryn I; Wetter, David W

    2006-01-01

    To examine relations among gender, self-generated smoking-outcome expectancies, and smoking in adolescents. Students from one all-girls' (n=350; 53%) and one all-boys' (n=315; 47%) Catholic high school participated. Analyses included binary and ordinal logistic regression. For boys, smoking behavior was associated with buzz (odds radio [OR] = 1.92, 95% confidence interval [CI]: 1.31-2.83, p exercise/sport impairment (OR = 2.84, 95% CI: 1.68-4.81, p gender-smoking relationship. Moderators included negative social (beta = -0.45, p = .021) and enhance self-esteem (beta = -1.07, p = .024). Interventions might benefit from tailoring on gender differences in smoking-outcome expectancies.

  12. User's manual for applicants proposing on-site burial of self-generated radioactive waste

    International Nuclear Information System (INIS)

    Tolbert, M.E.M.; Loretan, P.A.

    1987-01-01

    This document describes, for medical and research institutions as well as industrial generators of low-level radioactive waste, the NRC or state submittal requirements for authorizing the on-site burial of self-generated radioactive waste. An important part of completing the license application for operation justifying this alternative for waste disposal over other alternatives. Reasons that might be considered acceptable might include the need to dispose of large volumes of low activity waste that would otherwise take up valuable space in commercial sites; the ability to demonstrate that this method of disposal will result in reduced exposures to the public; the ability to show that the prohibitive costs of other methods of disposal would be detrimental to the progress of significant research which generates radioactive waste. 19 refs., 3 figs., 4 tabs

  13. SELF-GENERATED COPING STRATEGIES AMONG MUSLIM ATHLETES DURING RAMADAN FASTING

    Directory of Open Access Journals (Sweden)

    Jolly Roy

    2011-03-01

    Full Text Available The study explored the self-generated coping strategies employed by Muslim athletes from South East Asian region during the Ramadan fasting month. Sixty-five National elite Muslim athletes responded to an open-ended question on coping strategies employed during Ramadan fasting. Inductive content analysis identified five general dimensions from 54 meaning units which were abstracted into 14 first-order themes and 10 second order themes. The general dimension included four problem-focused coping: training modifications, dietary habits, psychological, rest and recovery, and one emotion-focused coping i.e., self- control. The coping strategies employed were diverse and dynamic in nature and no specific pattern was evident. The most frequently employed strategies were associated with training and dietary habits. Emotion focused coping was the least frequently used by the athletes

  14. Broadening of hydrogenic X rays emitted by a laser-produced plasma

    International Nuclear Information System (INIS)

    Nguyen, Hoe; Grumberg, J.; Caby, M.; Leboucher, E.; Coulaud, G.

    1980-01-01

    This study is devoted to X-rays broadened by laser impact or implosion. In addition to usual broadening processes due to the high and low components of plasma microfield, we have examined the influence of the self-generated magnetic field B which is correlated to the Doppler effect by the motional electric field. Concerning the interaction between plasma electrons and radiating ions with high charge number Zsub(E), it is shown that the curvature of electron trajectories must be taken into account in the broadening operator calculation. The influence of this curvature consists in reducing the contribution of dipolar interaction and enhancing the contribution of multipolar interactions with higher order. As a particular consequence on the half-width of Lyman-α-lines we have found values ten times larger than those obtained from the usual dipolar approximation. In the other hand, spectral lines emitted from the plasma critical region exhibits a strong self-generated magnetic field effect. Principally, it consists in polarizing the spectral profiles and introducing a large dependence with respect to the observation direction k. Particularly, profiles observed in the direction parallel to the magnetic field exhibit a deep central minimum which must be taken into account in a quantitative study of the line absorption properties [fr

  15. Mathematical and numerical analysis of the resistive magnetohydrodynamics system with self-generated magnetic field terms

    International Nuclear Information System (INIS)

    Wolff, Marc

    2011-01-01

    This work is devoted to the construction of numerical methods that allow the accurate simulation of inertial confinement fusion (ICF) implosion processes by taking self-generated magnetic field terms into account. In the sequel, we first derive a two-temperature resistive magnetohydrodynamics model and describe the considered closure relations. The resulting system of equations is then split in several subsystems according to the nature of the underlying mathematical operator. Adequate numerical methods are then proposed for each of these subsystems. Particular attention is paid to the development of finite volume schemes for the hyperbolic operator which actually is the hydrodynamics or ideal magnetohydrodynamics system depending on whether magnetic fields are considered or not. More precisely, a new class of high-order accurate dimensionally split schemes for structured meshes is proposed using the Lagrange re-map formalism. One of these schemes' most innovative features is that they have been designed in order to take advantage of modern massively parallel computer architectures. This property can for example be illustrated by the dimensionally split approach or the use of artificial viscosity techniques and is practically highlighted by sequential performance and parallel efficiency figures. Hyperbolic schemes are then combined with finite volume methods for dealing with the thermal and resistive conduction operators and taking magnetic field generation into account. In order to study the characteristics and effects of self-generated magnetic field terms, simulation results are finally proposed with the complete two-temperature resistive magnetohydrodynamics model on a test problem that represents the state of an ICF capsule at the beginning of the deceleration phase. (author)

  16. The role of amorphous phase content on the electrical properties of atmospheric plasma sprayed (Ba,Sr)TiO3 coatings

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Seshadri, R.C.; Sampath, S.; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 9 (2016), s. 11010-11014 ISSN 0272-8842 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : X-ray methods * Electrical properties * Perovskites * Atmospheric Plasma Spray Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884216303856

  17. The calculation of electron chemical potential and ion charge state and their influence on plasma conductivity in electrical explosion of metal wire

    International Nuclear Information System (INIS)

    Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli

    2014-01-01

    The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model

  18. Radar observations of density gradients, electric fields, and plasma irregularities near polar cap patches in the context of the gradient-drift instability

    Science.gov (United States)

    Lamarche, Leslie J.; Makarevich, Roman A.

    2017-03-01

    We present observations of plasma density gradients, electric fields, and small-scale plasma irregularities near a polar cap patch made by the Super Dual Auroral Radar Network radar at Rankin Inlet (RKN) and the northern face of Resolute Bay Incoherent Scatter Radar (RISR-N). RKN echo power and occurrence are analyzed in the context of gradient-drift instability (GDI) theory, with a particular focus on the previously uninvestigated 2-D dependencies on wave propagation, electric field, and gradient vectors, with the latter two quantities evaluated directly from RISR-N measurements. It is shown that higher gradient and electric field components along the wave vector generally lead to the higher observed echo occurrence, which is consistent with the expected higher GDI growth rate, but the relationship with echo power is far less straightforward. The RKN echo power increases monotonically as the predicted linear growth rate approaches zero from negative values but does not continue this trend into positive growth rate values, in contrast with GDI predictions. The observed greater consistency of echo occurrence with GDI predictions suggests that GDI operating in the linear regime can control basic plasma structuring, but measured echo strength may be affected by other processes and factors, such as multistep or nonlinear processes or a shear-driven instability.

  19. Recent advances in incoherent light sources in the vacuum-ultraviolet (88-200nm) based on electric discharge plasmas

    International Nuclear Information System (INIS)

    Ward, B.K.; Carman, R.J.; Mildren, R.P.; Kane, D.M.

    2004-01-01

    Full text: Rare-gas and rare gas-halide excimer lamps are powerful, frequency agile, mercury-free sources of high power, narrow band (10nm-30nm), UV and VUV radiation covering the wavelength range 88nm-320nm. A very efficient and practically convenient method of excitation is achieved using the dielectric barrier discharge (DBD). In the DBD, charge build-up on an insulating (dielectric) barrier at one or both of the electrodes provides an intrinsic mechanism for quenching the discharge before the transition to a high current discharge. The UV/VUV output from rare-gas DBD lamps is highly monochromatic, derived predominantly from 2nd excimer continuum, with negligible output at visible and infrared wavelengths. For DBD lamps powered by sinusoidal voltage waveforms (50Hz-100kHz), the electrical to optical conversion efficiency typically reaches 10-20%. The discharge structure consists of multiple transient plasma aments that occur stochastically in time during the discharge cycle leading to VUV output pulses with irregular spacing and amplitude. We have shown, however, that using discrete high-voltage pulses of relatively short duration, produces a short-lived homogeneous discharge that generates much higher peak power from short (sub-microsecond) VUV output pulses, with an additional increase (two- fold) in overall efficiency. Conversion efficiencies between 40-60% have also been reported for short-pulse excitation techniques. Efficient generation of pulsed, high peak-power VUV output is of interest for a broad range of applications in time-resolved spectroscopy, photo-lithography, materials processing and surface modification/cleaning, killing of micro- organisms and bacteria, sterilization, and in ozone production for water purification

  20. Influence of electric current on microstructure evolution in Ti/Al and Ti/TiAl{sub 3} during spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Haley, J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Kulkarni, K. [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208016, UP (India); Aindow, M. [Department of Materials Science and Engineering, Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Lavernia, E.J., E-mail: lavernia@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616-5294 (United States); Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States)

    2015-11-05

    The synthesis of γ-TiAl from elemental metals via solid-state reactive diffusion processing routes involves multiple reaction steps with the formation of various intermediate intermetallic compounds, starting with TiAl{sub 3} because this phase is favored kinetically. To understand the processes by which the TiAl{sub 3} intermediate is eliminated during synthesis of γ-TiAl alloy via spark plasma sintering (SPS), the reaction between Ti and TiAl{sub 3} during SPS was studied with emphasis on the effects of the applied electric current and starting TiAl{sub 3} microstructure on the reaction kinetics and the underlying diffusion mechanisms. The intermediate intermetallic phases Ti{sub 3}Al, TiAl and TiAl{sub 2} were formed between the Ti and TiAl{sub 3} upon SPS processing at 900 °C. The applied electric current did not alter the character of the phases formation in the Ti/TiAl{sub 3} system, but thermodynamic calculations suggest that the activation energy for the nucleation of TiAl{sub 2} is reduced significantly with an electric current flowing. Moreover, the kinetics of the reactions between Ti and TiAl{sub 3} were enhanced when the starting TiAl{sub 3} microstructure was refined. The electric field also had a more significant influence on the grain growth kinetics for TiAl{sub 2} and TiAl in powder blend compacts with refined microstructures. - Highlights: • Reaction between Ti and TiAl{sub 3} during spark plasma sintering was studied. • Refined starting TiAl{sub 3} microstructure enhanced the reactions kinetics. • The nucleation barrier of TiAl{sub 2} was reduced by the applied electric field. • The applied electric field restrained the grain growth of TiAl and TiAl{sub 2}.

  1. Dependence of current density and intensity of electric field on pulsation of thermodynamic parameters of plasma in the MHD generator

    International Nuclear Information System (INIS)

    Kapron, H.

    1976-01-01

    The investigations of pulsation in the MHD generators are described. The influence of termodynamic parameters pulsation on electric parameters of the MHD generator is presented using the method of little disturbances. The results of this investigation are formulas for momentary and average values of: electrical conductivity, the Hall parameter, current density and intensity of electrical field. Analitical investigations were verified by the experiments. (author)

  2. MONTE CARLO SIMULATION MODEL OF ENERGETIC PROTON TRANSPORT THROUGH SELF-GENERATED ALFVEN WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Afanasiev, A.; Vainio, R., E-mail: alexandr.afanasiev@helsinki.fi [Department of Physics, University of Helsinki (Finland)

    2013-08-15

    A new Monte Carlo simulation model for the transport of energetic protons through self-generated Alfven waves is presented. The key point of the model is that, unlike the previous ones, it employs the full form (i.e., includes the dependence on the pitch-angle cosine) of the resonance condition governing the scattering of particles off Alfven waves-the process that approximates the wave-particle interactions in the framework of quasilinear theory. This allows us to model the wave-particle interactions in weak turbulence more adequately, in particular, to implement anisotropic particle scattering instead of isotropic scattering, which the previous Monte Carlo models were based on. The developed model is applied to study the transport of flare-accelerated protons in an open magnetic flux tube. Simulation results for the transport of monoenergetic protons through the spectrum of Alfven waves reveal that the anisotropic scattering leads to spatially more distributed wave growth than isotropic scattering. This result can have important implications for diffusive shock acceleration, e.g., affect the scattering mean free path of the accelerated particles in and the size of the foreshock region.

  3. Enhanced alpha-oscillations in visual cortex during anticipation of self-generated visual stimulation.

    Science.gov (United States)

    Stenner, Max-Philipp; Bauer, Markus; Haggard, Patrick; Heinze, Hans-Jochen; Dolan, Ray

    2014-11-01

    The perceived intensity of sensory stimuli is reduced when these stimuli are caused by the observer's actions. This phenomenon is traditionally explained by forward models of sensory action-outcome, which arise from motor processing. Although these forward models critically predict anticipatory modulation of sensory neural processing, neurophysiological evidence for anticipatory modulation is sparse and has not been linked to perceptual data showing sensory attenuation. By combining a psychophysical task involving contrast discrimination with source-level time-frequency analysis of MEG data, we demonstrate that the amplitude of alpha-oscillations in visual cortex is enhanced before the onset of a visual stimulus when the identity and onset of the stimulus are controlled by participants' motor actions. Critically, this prestimulus enhancement of alpha-amplitude is paralleled by psychophysical judgments of a reduced contrast for this stimulus. We suggest that alpha-oscillations in visual cortex preceding self-generated visual stimulation are a likely neurophysiological signature of motor-induced sensory anticipation and mediate sensory attenuation. We discuss our results in relation to proposals that attribute generic inhibitory functions to alpha-oscillations in prioritizing and gating sensory information via top-down control.

  4. Self-generated persuasion: effects of the target and direction of arguments.

    Science.gov (United States)

    Briñol, Pablo; McCaslin, Michael J; Petty, Richard E

    2012-05-01

    Previous research has revealed that self-persuasion can occur either through role-playing (i.e., when arguments are generated to convince another person) or, more directly, through trying to convince oneself (i.e., when arguments are generated with oneself as the target). Combining these 2 traditions in the domain of attitude change, the present research investigated the impact on self-persuasion of the specific target of one's own persuasive attempt (i.e., others vs. oneself). We found that the efficacy of self-persuasion depended on whether people believed that they would have to put more or less effort in convincing the self or others. Specifically, we found opposite effects for self-generated arguments depending on whether the topic of persuasion was proattitudinal or counterattitudinal. Across 4 studies, it was shown that when the topic of the message was counterattitudinal, people were more effective in convincing themselves when the intended target of the arguments was themselves versus another person. However, the opposite was the case when the topic was proattitudinal. These effects were shown to stem from the differential effort perceived as necessary and actually exerted in trying to produce persuasion under these conditions.

  5. Wire Probe Antenna (WPT) and Electric Field Detector (EFD) of Plasma Wave Experiment (PWE) aboard the Arase satellite: specifications and initial evaluation results

    Science.gov (United States)

    Kasaba, Yasumasa; Ishisaka, Keigo; Kasahara, Yoshiya; Imachi, Tomohiko; Yagitani, Satoshi; Kojima, Hirotsugu; Matsuda, Shoya; Shoji, Masafumi; Kurita, Satoshi; Hori, Tomoaki; Shinbori, Atsuki; Teramoto, Mariko; Miyoshi, Yoshizumi; Nakagawa, Tomoko; Takahashi, Naoko; Nishimura, Yukitoshi; Matsuoka, Ayako; Kumamoto, Atsushi; Tsuchiya, Fuminori; Nomura, Reiko

    2017-12-01

    This paper summarizes the specifications and initial evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), the key components for the electric field measurement of the Plasma Wave Experiment (PWE) aboard the Arase (ERG) satellite. WPT consists of two pairs of dipole antennas with 31-m tip-to-tip length. Each antenna element has a spherical probe (60 mm diameter) at each end of the wire (15 m length). They are extended orthogonally in the spin plane of the spacecraft, which is roughly perpendicular to the Sun and enables to measure the electric field in the frequency range of DC to 10 MHz. This system is almost identical to the WPT of Plasma Wave Investigation aboard the BepiColombo Mercury Magnetospheric Orbiter, except for the material of the spherical probe (ERG: Al alloy, MMO: Ti alloy). EFD is a part of the EWO (EFD/WFC/OFA) receiver and measures the 2-ch electric field at a sampling rate of 512 Hz (dynamic range: ± 200 mV/m) and the 4-ch spacecraft potential at a sampling rate of 128 Hz (dynamic range: ± 100 V and ± 3 V/m), with the bias control capability of WPT. The electric field waveform provides (1) fundamental information about the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves in various magnetospheric statuses with the magnetic field measured by MGF and PWE-MSC. The spacecraft potential provides information on thermal electron plasma variations and structure combined with the electron density obtained from the upper hybrid resonance frequency provided by PWE-HFA. EFD has two data modes. The continuous (medium-mode) data are provided as (1) 2-ch waveforms at 64 Hz (in apoapsis mode, L > 4) or 256 Hz (in periapsis mode, L < 4), (2) 1-ch spectrum within 1-232 Hz with 1-s resolution, and (3) 4-ch spacecraft potential at 8 Hz. The burst (high-mode) data are intermittently obtained as (4) 2-ch waveforms at 512 Hz and (5) 4-ch spacecraft potential at 128 Hz and downloaded with the WFC

  6. The importance of the radial electric field (Er) on interpretation of motional Stark effect measurements of the q profile in DIII-D high performance plasmas

    International Nuclear Information System (INIS)

    Rice, B.W.; Lao, L.L.; Burrell, K.H.; Greenfield, C.M.; Lin-Liu, Y.R.

    1997-06-01

    The development of enhanced confinement regimes such as negative central magnetic shear (NCS) and VH-mode illustrates the importance of the q profile and ExB velocity shear in improving stability and confinement in tokamak plasmas. Recently, it was realized that the large values of radial electric field observed in these high performance plasmas, up to 200 kV/m in DIII-D, have an effect on the interpretation of motional Stark effect (MSE) measurements of the q profile. It has also been shown that, with additional MSE measurements, one can extract a direct measurement of E r in addition to the usual poloidal field measurement. During a recent vent on DIII-D, 19 additional MSE channels with new viewing angles were added (for a total of 35 channels) in order to descriminate between the neutral beam v b x B electric field and the plasma E r field. In this paper, the system upgrade will be described and initial measurements demonstrating simultaneous measurement of the q and E r profiles will be presented

  7. Studies of intense-laser plasma instabilities

    Czech Academy of Sciences Publication Activity Database

    Láska, Leoš; Krása, Josef; Badziak, J.; Jungwirth, Karel; Krouský, Eduard; Margarone, Daniele; Parys, P.

    2013-01-01

    Roč. 272, May (2013), 94-98 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA AV ČR IAA100100715 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser plasma instabilities * self-generated magnetic field * longitudinal structure of the expanding plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013

  8. Sensory suppression of brain responses to self-generated sounds is observed with and without the perception of agency.

    Science.gov (United States)

    Timm, Jana; Schönwiesner, Marc; Schröger, Erich; SanMiguel, Iria

    2016-07-01

    Stimuli caused by our own movements are given special treatment in the brain. Self-generated sounds evoke a smaller brain response than externally generated ones. This attenuated response may reflect a predictive mechanism to differentiate the sensory consequences of one's own actions from other sensory input. It may also relate to the feeling of being the agent of the movement and its effects, but little is known about how sensory suppression of brain responses to self-generated sounds is related to judgments of agency. To address this question, we recorded event-related potentials in response to sounds initiated by button presses. In one condition, participants perceived agency over the production of the sounds, whereas in another condition, participants experience an illusory lack of agency caused by changes in the delay between actions and effects. We compared trials in which the timing of button press and sound was physically identical, but participants' agency judgment differed. Results show reduced amplitudes of the auditory N1 component in response to self-generated sounds irrespective of agency experience, whilst P2 effects correlate with the perception of agency. Our findings suggest that suppression of the auditory N1 component to self-generated sounds does not depend on adaptation to specific action-effect time delays, and does not determine agency judgments, however, the suppression of the P2 component might relate more directly to the experience of agency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. A Proposed Model of Self-Generated Analogical Reasoning for the Concept of Translation in Protein Synthesis

    Science.gov (United States)

    Salih, Maria

    2008-01-01

    This paper explored and described the analogical reasoning occurring in the minds of different science achievement groups for the concept of translation in protein synthesis. "What is the process of self-generated analogical reasoning?", "What types of matching was involved?" and "What are the consequences of the matching…

  10. The Relationship of Training in Self-Generated Questioning with Passage Difficulty and Immediate and Delayed Retention.

    Science.gov (United States)

    Balajthy, Ernest

    A study was conducted to determine if covert reader-generation of interspersed prequestions would affect recall of science-oriented prose. Sixty college freshmen in a basic skills reading course were divided into three groups: Group I received 5 hours of training and practive in the construction of self-generated questions, including recognition…

  11. Narrative theory: II. Self-generated and experimenter-provided negative income shock narratives increase delay discounting.

    Science.gov (United States)

    Mellis, Alexandra M; Snider, Sarah E; Bickel, Warren K

    2018-04-01

    Reading experimenter-provided narratives of negative income shock has been previously demonstrated to increase impulsivity, as measured by discounting of delayed rewards. We hypothesized that writing these narratives would potentiate their effects of negative income shock on decision-making more than simply reading them. In the current study, 193 cigarette-smoking individuals from Amazon Mechanical Turk were assigned to either read an experimenter-provided narrative or self-generate a narrative describing either the negative income shock of job loss or a neutral condition of job transfer. Individuals then completed a task of delay discounting and measures of affective response to narratives, as well as rating various narrative qualities such as personal relevance and vividness. Consistent with past research, narratives of negative income shock increased delay discounting compared to control narratives. No significant differences existed in delay discounting after self-generating compared to reading experimenter-provided narratives. Positive affect was lower and negative affect was higher in response to narratives of job loss, but affect measures did not differ based on whether narratives were experimenter-provided or self-generated. All narratives were rated as equally realistic, but self-generated narratives (whether negative or neutral) were rated as more vivid and relevant than experimenter-provided narratives. These results indicate that the content of negative income shock narratives, regardless of source, consistently drives short-term choices. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  12. Quite time convection electric field properties derived from keV electron measurements at the inner edge of the plasma sheet by means of GEOS 2

    International Nuclear Information System (INIS)

    Reme, H.; Kremser, G.; Bahnsen, A.; Jespersen, M.; Hultqvist, B.; Borg, H.; Holmgren, L.Aa.

    1981-04-01

    From an analysis of the local time distribution of the electron upper energy limit reached by the geostationary satellite GEOS 2 in cutting through the innermost part of the electron plasma sheet during fairly quite condition the following results have been obtained, among others: An electric field model given by E = -grad(AR 4 sinphi), with the dusk singular point of the forbidden region boundary at 1500, instead of at 1800 MLT, is in quite good agreement with the observations. This means that effects due to the shielding by the hot plasma of the inner magnetosphere from the convection electric field are quite strong in situations of low disturbance level. The quiet time convection electric field strength at 2100 MLT in the geostationary orbit obtained from this analysis varies in the range 0.15 - 0.3 keV/Rsub(e). Six hours earlier or later in the satellite orbit the convection field is 4 times stronger. Also when the convection field varies, some information about its magnitude can be obtained from the keV electron measurements. (author)

  13. Fasting plasma triglycerides predict the glycaemic response to treatment of Type 2 diabetes by gastric electrical stimulation. A novel lipotoxicity paradigm

    Science.gov (United States)

    Lebovitz, H E; Ludvik, B; Yaniv, I; Haddad, W; Schwartz, T; Aviv, R

    2013-01-01

    Background Non-stimulatory, meal-mediated electrical stimulation of the stomach (TANTALUS-DIAMOND) improves glycaemic control and causes modest weight loss in patients with Type 2 diabetes who are inadequately controlled on oral anti-diabetic medications. The magnitude of the glycaemic response in clinical studies has been variable. A preliminary analysis of data from patients who had completed 6 months of treatment indicated that the glycaemic response to the electrical stimulation was inversely related to the baseline fasting plasma triglyceride level. Method An analysis of 40 patients who had had detailed longitudinal studies for 12 months. Results Twenty-two patients with fasting plasma triglycerides ≤ 1.7 mmol/l had mean decreases in HbA1c after 3, 6 and 12 months of gastric contraction modulation treatment of −15 ± 2.1 mmol/mol (−1.39 ± 0.20%), −16 ± 2.2 mmol/mol (−1.48 ± 0.20%) and −14 ± 3.0 mmol/mol (−1.31 ± 0.26%), respectively. In contrast, 18 patients with fasting plasma triglyceride > 1.7 mmol/l had mean decreases in HbA1c of −7 ± 1.7 mmol/mol (−0.66 ± 0.16%), −5 ± 1.6 mmol/mol (−0.44 ± 0.18%) and −5 ± 1.7 mmol/mol (−0.42 ± 0.16%), respectively. Pearson's correlation coefficient between fasting plasma triglyceride and decreases in HbA1c at 12 months of treatment was 0.34 (P triglycerides, while it progressively improved in patients with low fasting plasma triglycerides. Patients with low fasting plasma triglycerides had a tendency to lose more weight than those with high fasting plasma triglycerides, but this did not achieve statistical significance. Conclusions The data presented suggest the existance of a triglyceride lipotoxic mechanism that interferes with gastric/neural mediated pathways that can regulate glycaemic control in patients with type 2 diabetes. The data suggest the existence of a triglyceride lipotoxic pathway that interferes with gastric/neural mediated pathways that can regulate glycaemic control

  14. Examining causal components and a mediating process underlying self-generated health arguments for exercise and smoking cessation.

    Science.gov (United States)

    Baldwin, Austin S; Rothman, Alexander J; Vander Weg, Mark W; Christensen, Alan J

    2013-12-01

    Self-persuasion-generating one's own arguments for engaging in a specific behavior-can be an effective strategy to promote health behavior change, yet the causal processes that explain why it is effective are not well-specified. We sought to elucidate specific causal components and a mediating process of self-persuasion in two health behavior domains: physical activity and smoking. In two experiments, participants were randomized to write or read arguments about regular exercise (Study 1: N = 76; college students) or smoking cessation (Study 2: N = 107; daily smokers). In Study 2, we also manipulated the argument content (matched vs. mismatched participants' own concerns about smoking) to isolate its effect from the effect of argument source (self vs. other). Study outcomes included participants' reports of argument ratings, attitudes, behavioral intentions (Studies 1 & 2), and cessation attempts at 1 month (Study 2). In Study 1, self-generated arguments about exercise were evaluated more positively than other arguments (p = .01, d = .63), and this biased processing mediated the self-generated argument effect on attitudes toward exercise (β = .08, 95% CI = .01, .18). In Study 2, the findings suggested that biased processing occurs because self-generated argument content matches people's own health concerns and not because of the argument source (self vs. other). In addition, self-generated arguments indirectly led to greater behavior change intentions (Studies 1 & 2) and a greater likelihood of a smoking cessation attempt (Study 2). The findings elucidate a causal component and a mediating process that explain why self-persuasion and related behavior change interventions, such as motivational interviewing, are effective. Findings also suggest that self-generated arguments may be an efficient way to deliver message interventions aimed at changing health behaviors.

  15. Some nonlinear estimates for lateral propagation of self-generated B fields

    International Nuclear Information System (INIS)

    Goldman, S.R.

    1982-01-01

    We present nonlinear estimates which provide plausible guidelines and scalings for the lateral transport of magnetic fields due to laser-plasma interaction in both slab and cylindrical geometries. Limitations of the modelling are also indicated

  16. Electrical characteristics of thermal CVD B-doped Si films on highly strained Si epitaxially grown on Ge(100) by plasma CVD without substrate heating

    International Nuclear Information System (INIS)

    Sugawara, Katsutoshi; Sakuraba, Masao; Murota, Junichi

    2010-01-01

    Using an 84% relaxed Ge(100) buffer layer formed on Si(100) by electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (CVD), influence of strain upon electrical characteristics of B-doped Si film epitaxially grown on the Ge buffer have been investigated. For the thinner B-doped Si film, surface strain amount is larger than that of the thicker film, for example, strain amount reaches 2.0% for the thickness of 2.2 nm. It is found that the hole mobility is enhanced by the introduction of strain to Si, and the maximum enhancement of about 3 is obtained. This value is higher than that of the usually reported mobility enhancement by strain using Si 1 -x Ge x buffer. Therefore, introduction of strain using relaxed Ge film formed by ECR plasma enhanced CVD is useful to improve future Si-based device performance.

  17. 3D Numerical Analysis of the Arc Plasma Behavior in a Submerged DC Electric Arc Furnace for the Production of Fused MgO

    International Nuclear Information System (INIS)

    Wang Zhen; Wang Ninghui; Li Tie; Cao Yong

    2012-01-01

    A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.

  18. Effect of external magnetic field and variable dust electrical charge on the shape and propagation of solitons in the two nonthermal ions dusty plasma

    International Nuclear Information System (INIS)

    Ghalambor Dezfuly, S.; Dorranian, D.

    2012-01-01

    In this manuscript, the effect of dust electrical charge, nonthermal ions, and external magnetic field on the shape and propagation of solitons in dusty plasma with two nonthermal ions is studied theoretically. Using the reductive perturbation theory, the Zakharov-Kuznetsov equation for propagation of dust acoustic waves is extracted. Results show that external magnetic field does not affect the amplitude of solitary wave but width of solitons are effectively depend on the magnitude of external magnetic field. With increasing the charge of dust particles the amplitude of solution will increase while their width will decrease. Increasing the nonthermal ions lead to opposite effect.

  19. Self-Generated Motives for Not Gambling Among Young Adult Non-gamblers.

    Science.gov (United States)

    Rash, Christina L; McGrath, Daniel S

    2017-09-01

    Motivational models have been shown to usefully describe reasons for engaging in addictive behaviors including gambling disorder. Although most scales designed to measure motives have been derived statistically, self-generated open-ended responses have also shown utility for identifying unique motives for gambling. While the motivational structure for gambling disorder has been extensively explored, there has been a paucity of research examining motives for choosing not to gamble. This is not the case for other addictive behaviors such as alcohol use where motives for abstaining from drinking have been well defined. The primary goal of this study was to qualitatively explore and identify motives for not gambling in a sample of young adult non-gamblers using open-ended responses. A sample (N = 196) of undergraduate current non-gamblers, defined as no gambling activity over the previous 12 months, completed a series of questionnaires on demographics, gambling behavior, and alcohol consumption. Furthermore, they were asked to provide their top three reasons for not gambling in rank order. The results revealed eight specific motives for why participants chose not to gamble: 'financial reasons and risk aversion'; 'disinterest and other priorities'; 'personal and religious convictions'; 'addiction concerns'; 'influence of others' values'; 'awareness of the odds'; 'lack of access, opportunity, or skill'; and 'emotional distress'. Personal and religious convictions reasons were also related to lifetime non-drinking, suggesting that these motives are associated with decreased addictive behaviors in general. Ultimately, these results may help to inform the design of prevention strategies for gambling disorder.

  20. Is self-generated thought a means of social problem solving?

    Science.gov (United States)

    Ruby, Florence J. M.; Smallwood, Jonathan; Sackur, Jerome; Singer, Tania

    2013-01-01

    Appropriate social problem solving constitutes a critical skill for individuals and may rely on processes important for self-generated thought (SGT). The aim of the current study was to investigate the link between SGT and social problem solving. Using the Means-End Problem Solving task (MEPS), we assessed participants' abilities to resolve daily social problems in terms of overall efficiency and number of relevant means they provided to reach the given solution. Participants also performed a non-demanding choice reaction time task (CRT) and a moderately-demanding working memory task (WM) as a context in which to measure their SGT (assessed via thought sampling). We found that although overall SGT was associated with lower MEPS efficiency, it was also associated with higher relevant means, perhaps because both depend on the capacity to generate cognition that is independent from the hear and now. The specific content of SGT did not differentially predict individual differences in social problem solving, suggesting that the relationship may depend on SGT regardless of its content. In addition, we also found that performance at the WM but not the CRT was linked to overall better MEPS performance, suggesting that individuals good at social processing are also distinguished by their capacity to constrain attention to an external task. Our results provide novel evidence that the capacity for SGT is implicated in the process by which solutions to social problems are generated, although optimal problem solving may be achieved by individuals who display a suitable balance between SGT and cognition derived from perceptual input. PMID:24391621

  1. Confidence-Based Progress-Driven Self-Generated Goals for Skill Acquisition in Developmental Robots

    Directory of Open Access Journals (Sweden)

    Hung eNgo

    2013-11-01

    Full Text Available A reinforcement learning agent that autonomously explores its environment can utilize a curiosity drive to enable continual learning of skills, in the absence of any external rewards. We formulate curiosity-driven exploration, and eventual skill acquisition, as a selective sampling problem. Each environment setting provides the agent with a stream of instances. An instance is a sensory observation that, when queried, causes an outcome that the agent is trying to predict. After an instance is observed, a query condition, derived herein, tells whether its outcome is statistically known or unknown to the agent, based on the confidence interval of an online linear classifier. Upon encountering the first unknown instance, the agent "queries'' the environment to observe the outcome, which is expected to improve its confidence in the corresponding predictor. If the environment is in a setting where all instances are known, the agent generates a plan of actions to reach a new setting, where an unknown instance is likely to be encountered. The desired setting is a self-generated goal, and the plan of action, essentially a program to solve a problem, is a skill. The success of the plan depends on the quality of the agent's predictors, which are improved as mentioned above. For validation, this method is applied to both a simulated and real Katana robot arm in its "blocks-world'' environment. Results show that the proposed method generates sample-efficient curious exploration behavior, which exhibits developmental stages, continual learning, and skill acquisition, in an intrinsically-motivated playful agent.

  2. Tethered by Self-Generated Flow: Mucus String Augmented Feeding Current Generation in Larval Oysters

    Science.gov (United States)

    Jiang, H.; Wheeler, J.; Anderson, E.

    2016-02-01

    Marine zooplankton live in a nutritionally dilute environment. To survive, they must process an enormous volume of water relative to their own body volume for food. To achieve this, many zooplankters including copepods, invertebrate larvae, and protists create a feeding current to concentrate and transport food items to their food gathering structures. To enhance the efficiency of the feeding current, these zooplankters often rely on certain "tethering" mechanisms to retard their translational motion for producing a strong feeding current. The tethering force may include excess weight due to gravity, force from attachment to solid surfaces, and drag experienced by strategically placed morphological structures. Larval oysters are known from previous studies to release mucus strings during feeding, presumably for supplying a tethering force to enhance their feeding-current efficiency. But the underlying mechanism is unclear. In this study, we used a high-speed microscale imaging system (HSMIS) to observe the behavior of freely swimming and feeding larval oysters. We also used HSMIS to measure larval imposed feeding currents via a micro-particle image velocimetry (µPIV) technique. HSMIS allows observations along a vertically oriented focal plane in a relatively large water vessel with unprecedented spatial and temporal resolutions. Our high-speed videos show that a feeding larval oyster continuously released a long mucus string into its feeding current that flows downward; the feeding current subsequently dragged the mucus string downward. Analysis of our µPIV data combined with a hydrodynamic model further suggests that the drag force experienced by the mucus string in the feeding current contributes significantly to the tethering force required to generate the feeding current. Thus, mucus strings in larval oysters act as "anchors" in larval self-generated flow to actively tether the feeding larvae.

  3. Passive acoustic measurement of bedload grain size distribution using self-generated noise

    Directory of Open Access Journals (Sweden)

    T. Petrut

    2018-01-01

    Full Text Available Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

  4. Passive acoustic measurement of bedload grain size distribution using self-generated noise

    Science.gov (United States)

    Petrut, Teodor; Geay, Thomas; Gervaise, Cédric; Belleudy, Philippe; Zanker, Sebastien

    2018-01-01

    Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

  5. Consequences of ponderomotive effects at the plasma periphery on the electrical behaviour of a multijunction grill lower hybrid launcher

    International Nuclear Information System (INIS)

    Hurtak, O.; Klima, R.; Petrzilka, V.A.

    1991-01-01

    A radiofrequency power-plasma coupling code which takes into account ponderomotive effects at the plasma periphery is developed for a multijunction grill. At a frequency of 4.6 GHz, if the RF power density increases, the power reflection coefficient remains fairly low, while the distribution of power among subsidiary waveguides deteriorates. At lower frequencies, the danger of overloading individual waveguides is expected to be still greater. (author). Letter-to-the-editor. 14 refs, 4 figs

  6. Wire Probe Antenna (WPT) and Electric Field Detector (EFD0 of Plasma Wave Experiment (PWE) aboard ARASE: Specifications and Evaluation results

    Science.gov (United States)

    Matsuda, S.; Kasaba, Y.; Ishisaka, K.; Kasahara, Y.; Imachi, T.; Yagitani, S.; Kojima, H.; Kurita, S.; Shoji, M.; Hori, T.; Shinbori, A.; Teramoto, M.; Miyoshi, Y.; Nakagawa, T.; Takahashi, N.; Nishimura, Y.; Matsuoka, A.; Tsuchiya, F.; Kumamoto, A.; Nomura, R.

    2017-12-01

    This paper summarizes the specifications and the evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), which are the key parts of Plasma Wave Experiment (PWE) aboard the Arase satellite, in their initial operations and the beginning phase of the full observations. WPT consists of the two dipole antennas as electric field sensors with 32m tip-to-tip length, with a sphere probe (6 cm diameter) attached at each end of wires (length: 15-m). They are extended orthogonally in the spin plane which is roughly perpendicular to the Sun. It enables the PWE to measure the E-field from DC to 10 MHz. This system is almost compatible to the WPT of the Plasma Wave Investigation (PWI) aboard BepiColombo Mercury Magnetospheric Orbiter, except the material of the spherical probe (ERG: Aluminium alloy, MMO: Titanium-alloy). This paper shows the extended length evaluated by the Lorentz force (spacecraft velocity x B-field) and the antenna impedance as the basic information of the E-field measurement capability of the PWE E-field receivers, with the evaluation for the possible degradation of the probe surface coated by TiAlN as BepiColombo. EFD is the 2-channel low frequency electric receiver as a part of EWO (EFD/WFC/OFA), for the measurement of 2ch electric field in the spin-plane with the sampling rate of 512 Hz (dynamic range: +-200 mV/m, +-3 V/m) and the 4ch spacecraft potential with the sampling rate of 128 Hz (dynamic range: +-100 V), respectively, with the bias control capability fed to the WPT probes. The electric field in DC - 232Hz provides the capability to detect (1) the fundamental information of the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves with their Poynting vectors with the data measured by MGF and PWE/WFC-B connected to PWE/SCM. The spacecraft potential provides the electron density information with UHR frequency. This paper also introduces the data sets and their calibration status.

  7. Effects of H2/O2 mixed gas plasma treatment on electrical and optical property of indium tin oxide

    International Nuclear Information System (INIS)

    Kim, Jun Young; Lee, Dong-Min; Kim, Jae-Kwan; Yang, Su-Hwan; Lee, Ji-Myon

    2013-01-01

    Highlights: ► The specific resistivity of ITO was enhanced by H 2 + O 2 mixed gas plasma treatment. ► The transmittance was same as that of untreated ITO after plasma treatment. ► The process was carried out at room temperature without any step of post-treatment. - Abstract: This study examined the effects of H 2 and H 2 + O 2 mixed gas plasma treatment on the properties of ITO films. The films were deposited on corning glass by RF magnetron sputtering under Ar and Ar/O 2 mixed gas ambient. After a H 2 plasma treatment, the ITO films showed an improved specific resistance due to the formation of oxygen vacancies acting as shallow donors, but showed quenched transmittance due to the formation of agglomerated metals on the surface. After an H 2 + O 2 mixed gas plasma treatment, the specific resistance of the film was improved without deteriorating transmittance. The enhanced specific resistance by mixed gas plasma treatment was attributed to the formation of free electrons by the incorporation of H in the lattice.

  8. Measurement of the spectrum of electric-field fluctuations in a plasma by laser-fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Hildebrandt, J.; Kunze, H.

    1980-01-01

    Laser-fluorescence spectroscopy has been applied to measure the spectrum of electric wave fields with high temporal resolution in a pulsed hollow-cathode discharge. A low-frequency and a high-frequency component can be identified

  9. Extended use of a computation method for electrical conductivity-case of non-Saha-equilibrium plasmas

    International Nuclear Information System (INIS)

    Chen, R.L.W.

    1981-01-01

    The use of an equation obtained earlier for computing electrical conductivity may be extended to partially ionized gases which depart from the Saha equation, provided the electron velocity distributions do not deviate from the Maxwellian distribution. (author)

  10. Diagnostic of capacitively coupled radio frequency plasma from electrical discharge characteristics: comparison with optical emission spectroscopy and fluid model simulation

    Science.gov (United States)

    Xiang, HE; Chong, LIU; Yachun, ZHANG; Jianping, CHEN; Yudong, CHEN; Xiaojun, ZENG; Bingyan, CHEN; Jiaxin, PANG; Yibing, WANG

    2018-02-01

    The capacitively coupled radio frequency (CCRF) plasma has been widely used in various fields. In some cases, it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma. In this paper, a glass vacuum chamber and a pair of plate electrodes were designed and fabricated, using 13.56 MHz radio frequency (RF) discharge technology to ionize the working gas of Ar. This discharge was mathematically described with equivalent circuit model. The discharge voltage and current of the plasma were measured at different pressures and different powers. Based on the capacitively coupled homogeneous discharge model, the equivalent circuit and the analytical formula were established. The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation. The experimental results show that when RF discharge power is 50-300 W and pressure is 25-250 Pa, the average electron temperature is about 1.7-2.1 eV and the average electron density is about 0.5 × 1017-3.6 × 1017 m-3. Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.

  11. A model for the nonlocal transport and the associated distribution function deformation in magnetized laser-plasmas

    International Nuclear Information System (INIS)

    Nicolai, Ph.; Feugeas, J.L.; Schurtz, G.

    2006-01-01

    We present a model of nonlocal transport for multidimensional radiation magneto hydrodynamic codes. In laser-produced plasmas, it is now believed that the heat transfer can be strongly modified by the nonlocal nature of the electron conduction. Nevertheless other mechanisms as self generated magnetic fields may affect heat transport too. The model described in this work aims at extending the formula of G. Schurtz, Ph. Nicolai and M. Busquet to magnetized plasmas. A system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and applied to a physical problem in order to demonstrate the main features of the model. This new model should improve the prediction and the interpretation of the laser experiments, in particular when the non-local model alone does not seem sufficient to reproduce the experimental results. This model is being implemented in a new 2-dimensional hydrodynamic code

  12. A model for the nonlocal transport and the associated distribution function deformation in magnetized laser-plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Nicolai, Ph.; Feugeas, J.L.; Schurtz, G. [Bordeaux-1 Univ., Centre Lasers Intenses et Applications (UMR 5107) CEA-CNRS, 33 - Talence (France)

    2006-06-15

    We present a model of nonlocal transport for multidimensional radiation magneto hydrodynamic codes. In laser-produced plasmas, it is now believed that the heat transfer can be strongly modified by the nonlocal nature of the electron conduction. Nevertheless other mechanisms as self generated magnetic fields may affect heat transport too. The model described in this work aims at extending the formula of G. Schurtz, Ph. Nicolai and M. Busquet to magnetized plasmas. A system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and applied to a physical problem in order to demonstrate the main features of the model. This new model should improve the prediction and the interpretation of the laser experiments, in particular when the non-local model alone does not seem sufficient to reproduce the experimental results. This model is being implemented in a new 2-dimensional hydrodynamic code.

  13. Nonlinear magnetic electron tripolar vortices in streaming plasmas.

    Science.gov (United States)

    Vranjes, J; Marić, G; Shukla, P K

    2000-06-01

    Magnetic electron modes in nonuniform magnetized and unmagnetized streaming plasmas, with characteristic frequencies between the ion and electron plasma frequencies and at spatial scales of the order of the collisionless skin depth, are studied. Two coupled equations, for the perturbed (in the case of magnetized plasma) or self-generated (for the unmagnetized plasma case) magnetic field, and the temperature, are solved in the strongly nonlinear regime and stationary traveling solutions in the form of tripolar vortices are found.

  14. Convergence on Self - Generated vs. Crowdsourced Ideas in Crisis Response: Comparing Social Exchange Processes and Satisfaction with Process

    DEFF Research Database (Denmark)

    Seeber, Isabella; Merz, Alexander B.; Maier, Ronald

    2017-01-01

    engage in social exchange processes to converge on a few promising ideas. Traditionally, teams work on self-generated ideas. However, in a crowdsourcing scenario, such as public participation in crisis response, teams may have to process crowd-generated ideas. To better understand this new practice......Social media allow crowds to generate many ideas to swiftly respond to events like crises, public policy discourse, or online town hall meetings. This allows organizations and governments to harness the innovative power of the crowd. As part of this setting, teams that process crowd ideas must......, it is important to investigate how converging on crowdsourced ideas affects the social exchange processes of teams and resulting outcomes. We conducted a laboratory experiment in which small teams working in a crisis response setting converged on self-generated or crowdsourced ideas in an emergency response...

  15. Particle-in-cell simulations of fast magnetic field penetration into plasmas due to the Hall electric field

    International Nuclear Information System (INIS)

    Swanekamp, S.B.; Grossmann, J.M.; Fruchtman, A.; Oliver, B.V.; Ottinger, P.F.

    1996-01-01

    Particle-in-cell (PIC) simulations are used to study the penetration of magnetic field into plasmas in the electron-magnetohydrodynamic (EMHD) regime. These simulations represent the first definitive verification of EMHD with a PIC code. When ions are immobile, the PIC results reproduce many aspects of fluid treatments of the problem. However, the PIC results show a speed of penetration that is between 10% and 50% slower than predicted by one-dimensional fluid treatments. In addition, the PIC simulations show the formation of vortices in the electron flow behind the EMHD shock front. The size of these vortices is on the order of the collisionless electron skin depth and is closely coupled to the effects of electron inertia. An energy analysis shows that one-half the energy entering the plasma is stored as magnetic field energy while the other half is shared between internal plasma energy (thermal motion and electron vortices) and electron kinetic energy loss from the volume to the boundaries. The amount of internal plasma energy saturates after an initial transient phase so that late in time the rate that magnetic energy increases in the plasma is the same as the rate at which kinetic energy flows out through the boundaries. When ions are mobile it is observed that axial magnetic field penetration is followed by localized thinning in the ion density. The density thinning is produced by the large electrostatic fields that exist inside the electron vortices which act to reduce the space-charge imbalance necessary to support the vortices. This mechanism may play a role during the opening process of a plasma opening switch. copyright 1996 American Institute of Physics

  16. Energy conversion and concentration in a high-current gaseous discharge: Dense plasma spheromak in plasma focus experiments

    International Nuclear Information System (INIS)

    Kukushkin, A.B.; Rantsev-Kartinov, V.A.; Terentiev, A.R.

    1995-01-01

    Experimental results are presented which verify the possibility of the self-generated transformation of the magnetic field in plasma focus discharges to give a closed, spheromak-like magnetic configuration (SLMC). The energy conversion mechanism suggests a possibility of further concentrating the plasma power density by means of natural compressing the SLMC-trapped plasma by the residual magnetic field of the plasma focus discharge

  17. Production of internal transport barriers via self-generated mean flows in Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Fiore, C. L.; Ernst, D. R.; Podpaly, Y. A.; Howard, N. T.; Lee, Jungpyo; Reinke, M. L.; Rice, J. E.; Hughes, J. W.; Ma, Y. [MIT-PSFC, 77 Mass. Ave., Cambridge, Massachusetts 02139 (United States); Mikkelsen, D. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Rowan, W. L.; Bespamyatnov, I. [FRC, U of Texas at Austin, Austin, Texas 78712 (United States)

    2012-05-15

    New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti Almost-Equal-To Te, and with monotonic q profiles (q{sub min} < 1). C-Mod H-mode plasmas exhibit strong intrinsic co-current rotation that increases with increasing stored energy without external drive. When the resonance position is moved off-axis, the rotation decreases in the center of the plasma resulting in a radial toroidal rotation profile with a central well which deepens and moves farther off-axis when the ICRF resonance location reaches the plasma half-radius. This profile results in strong E Multiplication-Sign B shear (>1.5 Multiplication-Sign 10{sup 5} rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.

  18. Adrenal Chromaffin Cells Exposed to 5-ns Pulses Require Higher Electric Fields to Porate Intracellular Membranes than the Plasma Membrane: An Experimental and Modeling Study.

    Science.gov (United States)

    Zaklit, Josette; Craviso, Gale L; Leblanc, Normand; Yang, Lisha; Vernier, P Thomas; Chatterjee, Indira

    2017-10-01

    Nanosecond-duration electric pulses (NEPs) can permeabilize the endoplasmic reticulum (ER), causing release of Ca 2+ into the cytoplasm. This study used experimentation coupled with numerical modeling to understand the lack of Ca 2+ mobilization from Ca 2+ -storing organelles in catecholamine-secreting adrenal chromaffin cells exposed to 5-ns pulses. Fluorescence imaging determined a threshold electric (E) field of 8 MV/m for mobilizing intracellular Ca 2+ whereas whole-cell recordings of membrane conductance determined a threshold E-field of 3 MV/m for causing plasma membrane permeabilization. In contrast, a 2D numerical model of a chromaffin cell, which was constructed with internal structures representing a nucleus, mitochondrion, ER, and secretory granule, predicted that exposing the cell to the same 5-ns pulse electroporated the plasma and ER membranes at the same E-field amplitude, 3-4 MV/m. Agreement of the numerical simulations with the experimental results was obtained only when the ER interior conductivity was 30-fold lower than that of the cytoplasm and the ER membrane permittivity was twice that of the plasma membrane. A more realistic intracellular geometry for chromaffin cells in which structures representing multiple secretory granules and an ER showed slight differences in the thresholds necessary to porate the membranes of the secretory granules. We conclude that more sophisticated cell models together with knowledge of accurate dielectric properties are needed to understand the effects of NEPs on intracellular membranes in chromaffin cells, information that will be important for elucidating how NEPs porate organelle membranes in other cell types having a similarly complex cytoplasmic ultrastructure.

  19. A review on application of MHD theory to plasma boundary problems in tokamaks

    International Nuclear Information System (INIS)

    Itoh, Kimitaka.

    1992-08-01

    A survey is made on the problems of the edge plasmas, to which the analyses based on the MHD theory have been successfully applied. Also discussed are the efforts to extend the model equation to more general (and important as well) problems such as H-mode physics. An overview is first made on the advantages of the MHD picture, and the necessary supplementary physics are examined. Next, one- and two-dimensional models of the spatial structure of the edge plasma is discussed. The results on the stationary structure, both analytical and numerical, are reviewed: Typical example as well as the scaling law are shown. The instabilities associated with edge plasma is next reviewed. The surface kink mode, ballooning mode, interchange mode, resistive interchange mode and thermal instability are discussed. Role of the geometry such as the location of the X-point is studied. Influences of the atomic processes, and those of the radial electric field are also discussed. The analysis of the H-mode transition physics is finally discussed. The boundary plasma is a nonlinear media which possesses the possibility for bifurcation in which the radial electric field plays a key role. The model of the ion viscosity is also studied. Transition physics is developed. Analysis on the self-generating oscillation is shown and the relation with ELMs is discussed. After reviewing these problems, several comments are made to what directions the study can be deepened. (author) 53 refs

  20. 10 Hz rTMS over right parietal cortex alters sense of agency during self-generated movements

    Directory of Open Access Journals (Sweden)

    Anina eRitterband-Rosenbaum

    2014-06-01

    Full Text Available A large body of fMRI and lesion-literature has provided evidence that the Inferior Parietal Cortex (IPC is important for sensorimotor integration and sense of agency (SoA. We used repetitive transcranial magnetic stimulation (rTMS to explore the role of the IPC during a validated SoA detection task. 12 healthy, right-handed adults were included. The effects of rTMS on subjects’ SoA during self-generated movements were explored. The experiment consisted of 1/3 self-generated movements and 2/3 computer manipulated movements that introduced uncertainty as to whether the subjects were agents of an observed movement. Subjects completed three sessions, in which subjects received online rTMS over the right IPC (active condition, over the vertex (CZ (sham condition or no TMS but a sound-matched control. We found that rTMS over right IPC significantly altered SoA of the non-perturbed movements. Following IPC stimulation subjects were more likely to experience self-generated movements as being externally perturbed compared to the control site (P=0.002 and the stimulation-free control (P=0.042. The data support the importance of IPC activation during sensorimotor comparison in order to correctly determine the agent of movements.

  1. The era of the wandering mind? Twenty-first century research on self-generated mental activity

    Directory of Open Access Journals (Sweden)

    Felicity eCallard

    2013-12-01

    Full Text Available The first decade of the twenty-first century was characterized by renewed scientific interest in self-generated mental activity (activity largely generated by the individual, rather than in response to experimenters’ instructions or specific external sensory inputs. To understand this renewal of interest, we interrogated the peer-reviewed literature from 2003–2012 (i to explore recent changes in use of terms for self-generated mental activity; (ii to investigate changes in the topics on which mind wandering research, specifically, focuses; and (iii to visualize co-citation communities amongst researchers working on self-generated mental activity. Our analyses demonstrated that there has been a dramatic increase in the term mind wandering, and a significant crossing-over of psychological investigations of mind wandering, specifically, into cognitive neuroscience. If this is, indeed, the ‘era of the wandering mind’, our paper calls for more explicit reflection to be given by mind wandering researchers to the terms they use, the topics and brain regions they focused on, and the research literatures that they implicitly foreground or ignore as not relevant.

  2. Special issue: Plasma Conversion

    NARCIS (Netherlands)

    Nozaki, T.; Bogaerts, A.; Tu, X.; van de Sanden, M. C. M.

    2017-01-01

    With growing concern of energy and environmental issues, the combination of plasma and heterogeneous catalysts receives special attention in greenhouse gas conversion, nitrogen fixation and hydrocarbon chemistry. Plasma gas conversion driven by renewable electricity is particularly important for the

  3. Neutrino beam plasma instability

    Indian Academy of Sciences (India)

    positron or electron–proton plasma in the context of early universe, stars and supernova ... proper. Of course, in their later work on kinetic theory (KT) [5] of neutrino plasma inter- .... for electron also with additional electric potential term.

  4. Electrical resistivity change in Al:ZnO thin films dynamically deposited by bipolar pulsed direct-current sputtering and a remote plasma source

    International Nuclear Information System (INIS)

    Yang, Wonkyun; Joo, Junghoon

    2010-01-01

    The Al-doped ZnO (AZO) thin films for a transparent conducting oxide in solar cell devices were deposited by bipolar pulsed dc magnetron sputtering. This work was performed in an in-line type system and investigated AZO films in a static deposition mode and dynamic one, which is more important in the practical fields. Because of this dynamic deposition process, the zigzagged columnar structure was observed. This resulted in the decreasing electrical property, optical properties, and surface roughness. As a deposition in the dynamic mode, the resistivity increased from 1.64x10 -3 to 2.50x10 -3 Ω cm, as compared to that in the static mode, and the transmittance also decreased from 83.9% to 78.3%. To recover the disadvantage, a remote plasma source (RPS) was supported between the substrate and target for reducing zigzagged formation during the deposition. The deposition rate decreased by using RPS, but the electrical and optical properties of films got better than only dynamic mode. The resistivity and transmittance in the dynamic mode using RPS were 2.1x10 -3 Ω cm and 85.5%, respectively. In this study, the authors found the possibility to advance the electrical and optical properties of AZO thin films in the industry mode.

  5. Fundamental investigations of capacitive radio frequency plasmas: simulations and experiments

    International Nuclear Information System (INIS)

    Donkó, Z; Derzsi, A; Hartmann, P; Korolov, I; Schulze, J; Czarnetzki, U; Schüngel, E

    2012-01-01

    Capacitive radio frequency (RF) discharge plasmas have been serving hi-tech industry (e.g. chip and solar cell manufacturing, realization of biocompatible surfaces) for several years. Nonetheless, their complex modes of operation are not fully understood and represent topics of high interest. The understanding of these phenomena is aided by modern diagnostic techniques and computer simulations. From the industrial point of view the control of ion properties is of particular interest; possibilities of independent control of the ion flux and the ion energy have been utilized via excitation of the discharges with multiple frequencies. ‘Classical’ dual-frequency (DF) discharges (where two significantly different driving frequencies are used), as well as discharges driven by a base frequency and its higher harmonic(s) have been analyzed thoroughly. It has been recognized that the second solution results in an electrically induced asymmetry (electrical asymmetry effect), which provides the basis for the control of the mean ion energy. This paper reviews recent advances on studies of the different electron heating mechanisms, on the possibilities of the separate control of ion energy and ion flux in DF discharges, on the effects of secondary electrons, as well as on the non-linear behavior (self-generated resonant current oscillations) of capacitive RF plasmas. The work is based on a synergistic approach of theoretical modeling, experiments and kinetic simulations based on the particle-in-cell approach. (paper)

  6. Electrical and spectral characteristics of an atmospheric pressure argon plasma jet generated with tube-ring electrodes in surface dielectric barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Y. [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Department of Physics and Electrical Engineering, Weinan Teachers University, Weinan 71400 (China); Lu, N. [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Pan, J. [Department of Physics and Electrical Engineering, Weinan Teachers University, Weinan 71400 (China); Li, J., E-mail: lijie@dlut.edu.cn [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China); Wu, Y. [Institute of Electrostatics and Special Power, Dalian University of Technology, Dalian 116024 (China)

    2013-03-01

    An atmospheric-pressure argon plasma jet is generated with tube-ring electrodes in surface dielectric barrier discharge by a sinusoidal excitation voltage at 8 kHz. The electrical and spectral characteristics are estimated such as conduction and displacement current, electric-field, electron temperature, rotational temperature of N{sub 2} and OH, electronic excitation temperature, and oxygen atomic density. It is found that the electric-field magnitudes in the top area of the ground electrode are higher than that in the bottom area of the power electrode, and the electron temperature along radial direction is in the range of 9.6–10.4 eV and along axial direction in the range of 4.9–10 eV. The rotational temperature of N{sub 2} obtained by comparing the simulated spectrum with the measured spectrum at the C{sup 3}Π{sub u} → B{sup 3}Π{sub g}(Δv = − 2) band transition is in the range of 342–387 K, the electronic excitation temperature determined by Boltzmann's plot method is in the range of 3188–3295 K, and the oxygen atomic density estimated by the spectral intensity ratio of atomic oxygen line λ = 844.6 nm to argon line λ = 750.4 nm is in the order of magnitude of 10{sup 16} cm{sup −3}, respectively. - Highlights: ► The conduction and displacement current are calculated by equivalent circuit diagram. ► The 2D distribution of electric-field magnitude is calculated by ElecNet software. ► The electron temperature along axial direction is in the range of 4.9–10 eV. ► The oxygen atomic density is about a magnitude of 10{sup 16} cm{sup −3}.

  7. Plasma technology

    International Nuclear Information System (INIS)

    Drouet, M.G.

    1984-03-01

    IREQ was contracted by the Canadian Electrical Association to review plasma technology and assess the potential for application of this technology in Canada. A team of experts in the various aspects of this technology was assembled and each team member was asked to contribute to this report on the applications of plasma pertinent to his or her particular field of expertise. The following areas were examined in detail: iron, steel and strategic-metals production; surface treatment by spraying; welding and cutting; chemical processing; drying; and low-temperature treatment. A large market for the penetration of electricity has been identified. To build up confidence in the technology, support should be provided for selected R and D projects, plasma torch demonstrations at full power, and large-scale plasma process testing

  8. Investigation of plasma turbulence and local electric field in the T-10 tokamak and TJ-II stellarator by HIBP diagnostic (Review)

    International Nuclear Information System (INIS)

    Krupnik, L.I.; Chmuga, A.A.; Komarov, A.D.; Kozachek, A.S.; Zhezhera, A.I.; Melnikov, A.V.; Eliseev, L.G.; Lysenko, S.E.; Mavrin, V.A.; Perfilov, S.V.; Hidalgo, C.; Ascasibar, E.; Estrada, T.; Ochando, M.A.; Pablos, J.L.; Pedrosa, M.A.; Tabares, F.

    2011-01-01

    Direct study of the electric potential and its fluctuations for comparable plasma conditions in the T-10 tokamak and TJ-II stellarator by HIBP diagnostics has been performed. The following similar features of potential were found: the scale of several hundred Volts; the negative sign for densities n e >1x10 19 m -3 and comparable values in spite of the different heating methods. When ne or τ E rises, the potential evolves to negative values. During ECR heating and associated T e rise, τ E degrades and the potential evolves to positive direction. Oscillations of potential and density in the range of Geodesic Acoustic Modes in T-10 and Alfven Eigenmodes in TJ-II were observed.

  9. Production of internal transport barriers via self-generated mean flows in Alcator C-Moda)

    Science.gov (United States)

    Fiore, C. L.; Ernst, D. R.; Podpaly, Y. A.; Mikkelsen, D.; Howard, N. T.; Lee, Jungpyo; Reinke, M. L.; Rice, J. E.; Hughes, J. W.; Ma, Y.; Rowan, W. L.; Bespamyatnov, I.

    2012-05-01

    New results suggest that changes observed in the intrinsic toroidal rotation influence the internal transport barrier (ITB) formation in the Alcator C-Mod tokamak [E. S. Marmar and Alcator C-Mod group, Fusion Sci. Technol. 51, 261 (2007)]. These arise when the resonance for ion cyclotron range of frequencies (ICRF) minority heating is positioned off-axis at or outside of the plasma half-radius. These ITBs form in a reactor relevant regime, without particle or momentum injection, with Ti ≈ Te, and with monotonic q profiles (qmin 1.5 × 105 rad/s) in the region where the ITB foot is observed. Gyrokinetic analyses indicate that this spontaneous shearing rate is comparable to the linear ion temperature gradient (ITG) growth rate at the ITB location and is sufficient to reduce the turbulent particle and energy transport. New and detailed measurement of the ion temperature demonstrates that the radial profile flattens as the ICRF resonance position moves off axis, decreasing the drive for the ITG the instability as well. These results are the first evidence that intrinsic rotation can affect confinement in ITB plasmas.

  10. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    Science.gov (United States)

    Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

    2013-04-01

    The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

  11. Preliminary Study of Mixing of Plasma Species in a Hybrid-Stabilized Argon-Water Electric Arc

    Czech Academy of Sciences Publication Activity Database

    Jeništa, Jiří; Takana, H.; Uehara, S.; Nishiyama, H.; Murphy, A.B.; Bartlová, M.; Aubrecht, V.

    2015-01-01

    Roč. 2, č. 3 (2015), s. 316-319 ISSN 2336-2626. [Symposium on Physics of Switching Arc/21./. Nové Město na Moravě, 07.09.2015-11.09.2015] R&D Project s: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : arc discharge * combined diffusion coefficients * inhomogeneous mixing * mass fraction Subject RIV: BL - Plasma and Gas Discharge Physics https://www.vutbr.cz/www_base/vutdisk.php?i=36809a9aa

  12. Properties and electric characterizations of tetraethyl orthosilicate-based plasma enhanced chemical vapor deposition oxide film deposited at 400 °C for through silicon via application

    International Nuclear Information System (INIS)

    Su, Meiying; Yu, Daquan; Liu, Yijun; Wan, Lixi; Song, Chongshen; Dai, Fengwei; Xue, Kai; Jing, Xiangmeng; Guidotti, Daniel

    2014-01-01

    The dielectric via liner of through silicon vias was deposited at 400 °C using a tetraethyl orthosilicate (TEOS)-based plasma enhanced chemical vapor deposition process in a via-middle integration scheme. The morphology, conformality and chemical compositions of the liner film were characterized using field emission scanning electron microscopy and Fourier Transform Infrared spectroscopy. The thermal properties and electrical performance of blanket TEOS films were investigated by high temperature film stress and mercury probe Capacitance–Voltage measurements. The TEOS SiO 2 films show good conformality, excellent densification, low thermal stress, high breakdown voltage and low current leakage. - Highlights: • Tetraethyl orthosilicate-based oxide films were deposited for packaging application. • The oxide films deposited plasma-enhanced chemical vapor deposition (PECVD) at 400 °C. • The PECVD oxide films exhibit good step coverage. • The 400 °C PECVD oxide films exhibit low thermal stress and current leakage. • The 400 °C PECVD oxide films show high breakdown voltage and acceptable permittivity

  13. Structural, Optical, and Electrical Characterization of β-Ga2O3 Thin Films Grown by Plasma-Assisted Molecular Beam Epitaxy Suitable for UV Sensing

    Directory of Open Access Journals (Sweden)

    Abraham Arias

    2018-01-01

    Full Text Available β-Ga2O3 thin films were grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The films were grown using an elemental gallium source and oxygen supplied by an RF plasma source. Reflection high-energy electron diffraction (RHEED was used to monitor the surface quality in real time. Both in situ RHEED and ex situ X-ray diffraction confirmed the formation of single crystal β-phase films with excellent crystallinity on c-plane sapphire. Spectroscopic ellipsometry was used to determine the film thicknesses, giving values in the 11.6–18.8 nm range and the refractive index dispersion curves. UV-Vis transmittance measurements revealed that strong absorption of β-Ga2O3 starts at ∼270 nm. Top metal contacts were deposited by thermal evaporation for I-V characterization, which has been carried out in dark, as well as under visible and UV light illumination. The optical and electrical measurements showed that the grown thin films of β-Ga2O3 are excellent candidates for deep-ultraviolet detection and sensing.

  14. Properties and electric characterizations of tetraethyl orthosilicate-based plasma enhanced chemical vapor deposition oxide film deposited at 400 °C for through silicon via application

    Energy Technology Data Exchange (ETDEWEB)

    Su, Meiying, E-mail: sumeiying@ime.ac.cn [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); National Center for Advanced Packaging, Wuxi 214135 (China); Yu, Daquan, E-mail: yudaquan@ime.ac.cn [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); National Center for Advanced Packaging, Wuxi 214135 (China); Jiangsu R and D Center for Internet of Things, Wuxi 214135 (China); Liu, Yijun [Piotech Co. Ltd, Shenyang 110179 (China); Wan, Lixi [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Song, Chongshen; Dai, Fengwei [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); National Center for Advanced Packaging, Wuxi 214135 (China); Xue, Kai [National Center for Advanced Packaging, Wuxi 214135 (China); Jing, Xiangmeng [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); National Center for Advanced Packaging, Wuxi 214135 (China); Guidotti, Daniel [Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China)

    2014-01-01

    The dielectric via liner of through silicon vias was deposited at 400 °C using a tetraethyl orthosilicate (TEOS)-based plasma enhanced chemical vapor deposition process in a via-middle integration scheme. The morphology, conformality and chemical compositions of the liner film were characterized using field emission scanning electron microscopy and Fourier Transform Infrared spectroscopy. The thermal properties and electrical performance of blanket TEOS films were investigated by high temperature film stress and mercury probe Capacitance–Voltage measurements. The TEOS SiO{sub 2} films show good conformality, excellent densification, low thermal stress, high breakdown voltage and low current leakage. - Highlights: • Tetraethyl orthosilicate-based oxide films were deposited for packaging application. • The oxide films deposited plasma-enhanced chemical vapor deposition (PECVD) at 400 °C. • The PECVD oxide films exhibit good step coverage. • The 400 °C PECVD oxide films exhibit low thermal stress and current leakage. • The 400 °C PECVD oxide films show high breakdown voltage and acceptable permittivity.

  15. Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

    Energy Technology Data Exchange (ETDEWEB)

    Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Nersisyan, G.; Hanton, F.; Naughton, K.; Lewis, C. L. S.; Borghesi, M. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Brauckmann, S.; Giesecke, A. L.; Willi, O. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany)

    2016-05-15

    As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.

  16. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    Energy Technology Data Exchange (ETDEWEB)

    Sulyaeva, Veronica S., E-mail: veronica@niic.nsc.ru [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A. [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, Valerii G. [Laboratory of Physical Principles for Integrated Microelectronics, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Kirienko, Viktor V. [Laboratory of Nonequilibrium Semiconductors Systems, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation)

    2014-05-02

    Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers (93%). • BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9.

  17. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    International Nuclear Information System (INIS)

    Sulyaeva, Veronica S.; Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A.; Kesler, Valerii G.; Kirienko, Viktor V.

    2014-01-01

    Thin BC x N y films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC x N y films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC x N y layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC x N y films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC x N y films were found to be high optical transparent layers (93%). • BC x N y layers are dielectrics with dielectric constant k = 2.2–8.9

  18. Evolution of three-dimensional relativistic current sheets and development of self-generated turbulence

    Science.gov (United States)

    Takamoto, M.

    2018-05-01

    In this paper, the temporal evolution of three-dimensional relativistic current sheets in Poynting-dominated plasma is studied for the first time. Over the past few decades, a lot of efforts have been conducted on studying the evolution of current sheets in two-dimensional space, and concluded that sufficiently long current sheets always evolve into the so-called plasmoid chain, which provides a fast reconnection rate independent of its resistivity. However, it is suspected that plasmoid chain can exist only in the case of two-dimensional approximation, and would show transition to turbulence in three-dimensional space. We performed three-dimensional numerical simulation of relativistic current sheet using resistive relativistic magnetohydrodynamic approximation. The results showed that the three-dimensional current sheets evolve not into plasmoid chain but turbulence. The resulting reconnection rate is 0.004, which is much smaller than that of plasmoid chain. The energy conversion from magnetic field to kinetic energy of turbulence is just 0.01 per cent, which is much smaller than typical non-relativistic cases. Using the energy principle, we also showed that the plasmoid is always unstable for a displacement in the opposite direction to its acceleration, probably interchange-type instability, and this always results in seeds of turbulence behind the plasmoids. Finally, the temperature distribution along the sheet is discussed, and it is found that the sheet is less active than plasmoid chain. Our finding can be applied for many high-energy astrophysical phenomena, and can provide a basic model of the general current sheet in Poynting-dominated plasma.

  19. Magnetic reconnection in the presence of externally driven and self-generated turbulence

    International Nuclear Information System (INIS)

    Karimabadi, H.; Lazarian, A.

    2013-01-01

    Magnetic reconnection is an important process that violates flux freezing and induces change of magnetic field topology in conducting fluids and, as a consequence, converts magnetic field energy into particle energy. It is thought to be operative in laboratory, heliophysical, and astrophysical plasmas. These environments exhibit wide variations in collisionality, ranging from collisionless in the Earth's magnetosphere to highly collisional in molecular clouds. A common feature among these plasmas is, however, the presence of turbulence. We review the present understanding of the effects of turbulence on the reconnection rate, discussing both how strong pre-existing turbulence modifies Sweet-Parker reconnection and how turbulence may develop as a result of reconnection itself. In steady state, reconnection rate is proportional to the aspect ratio of the diffusion region. Thus, two general MHD classes of models for fast reconnection have been proposed, differing on whether they keep the aspect ratio finite by increasing the width due to turbulent broadening or shortening the length of the diffusion layer due to plasmoid instability. One of the consequences of the plasmoid instability model is the possibility that the current sheet thins down to collisionless scales where kinetic effects become dominant. As a result, kinetic effects may be of importance for many astrophysical applications which were considered to be in the realm of MHD. Whether pre-existing turbulence can significantly modify the transition to the kinetic regime is not currently known. Although most studies of turbulent reconnection have been based on MHD, recent advances in kinetic simulations are enabling 3D studies of turbulence and reconnection in the collisionless regime. A summary of these recent works, highlighting similarities and differences with the MHD models of turbulent reconnection, as well as comparison with in situ observations in the magnetosphere and in the solar wind, are presented

  20. Cosmic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Alfven, H [California Univ., San Diego, La Jolla (USA)

    1981-01-01

    The properties of space plasmas are analyzed, based on laboratory results and data obtained by in situ measurements in the magnetosphere (including the heliosphere). Attention is given to the question of how much knowledge can be gained by a systematic comparison of different regions of plasma, and plasmas are considered with linear dimensions varying from laboratory size up to the Hubble distance. The traditional magnetic field description of plasmas is supplemented by an electric current description and it is demonstrated that many problems are easier to understand with a dualistic approach. Using the general plasma properties obtained, the origin and evolution of the solar system is summarized and the evolution and present structure of the universe (cosmology) is discussed.