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Plasma Science, IEEE Transactions on

Issue 6  Part 2 • Date Dec. 2005

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Displaying Results 1 - 19 of 19
  • Table of contents

    Publication Year: 2005 , Page(s): c1
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  • IEEE Transactions on Plasma Science publication information

    Publication Year: 2005 , Page(s): c2
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  • Modified branching ratio method for absolute intensity calibration in VUV spectroscopy

    Publication Year: 2005 , Page(s): 1961 - 1967
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB) |  | HTML iconHTML  

    A new modified branching ratio (MBR) method for the absolute intensity calibration of a vacuum ultraviolet (VUV) spectrometer is presented. The spectrometer is equipped with a multichannel detector, consisting of an open microchannel plate coupled to a charge-coupled device (CCD), or with a single channel photomultiplier. This technique extends the number of calibration points available from those provided by the branching ratio (BR) calibration technique. The MBR method is a variation of the conventional BR method, where we relax the condition that the two spectral emissions, in the visible and VUV spectra, come from the same excited level, to include transitions from different sublevels of the same energy level. However, a critical study of the statistical equilibrium of sublevels from the same ion energy level was necessary. As a result, we have more than doubled the number of calibration points for our spectrometer used in tokamak plasma diagnostics. The appropriate identification of new spectral line pairs for absolute calibration here presented opens the path for future works in other devices with similar plasma conditions or impurities content. View full abstract»

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  • Temporal and spatial formation of the glow discharge in neon filled diode at 4 mbar pressure

    Publication Year: 2005 , Page(s): 1968 - 1972
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    The results of the investigation of the glow discharge time and space development in the neon-filled diode at 4 mbar are presented. The glow is of the diffusion type with saturation current value 0.2 mA. The temporal development of current and light intensity of the 585.2-nm line (originated from the negative glow) emitted perpendicularly on the diode axis from different parts of the diode, are registered. Electrically registered (by the oscilloscope), the total current through the diode reaches the saturation for 3 ms, which corresponds to the formative time delay. On the other hand, the value of the formative time delay estimated statistically from the series of 5000 breakdowns is 4.7 ms. The difference in formative time delays is associated with the pre-breakdown current growth in the gap. The prebreakdown current is registered measuring the emitted light from diode gap. The investigation of light shows the increase of excitation in the gap at least 1.25 ms before any significant current is registered (I<1 μA). The negative glow appears in the diode gap and in the next a few milliseconds covers the cathode, which indicates the presence of the multiplication processes in diode. The stationary regime in the diode is established for about 10 ms. These results show the validity of the statistical approach in the breakdown time delay investigations and in the understanding the nature of the formative time delays. View full abstract»

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  • Efficient and consistent methodology for the calculation of population densities, partition functions, and thermodynamic properties of ideal and weakly non-ideal multicomponent plasma mixtures in the P-T phase space

    Publication Year: 2005 , Page(s): 1973 - 1983
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    A set of nonideal Saha equations, for multicomponent plasma mixtures, can be derived from the conditions of the minimization of the free energy function in the ionization processes. Population densities derived from the solution of this set of equations subjected to electro-neutrality and conservation of nuclei are fully consistent with the thermodynamic properties derived from the same free energy function and, therefore, can be used to calculate these properties. Depending on the degree of complexity of the free energy function, nonideal Saha equations are obtained with different forms of nonideality corrections. In most practical situations, the problem of solving the resulting system of coupled nonlinear Saha equations, subjected to the above mentioned constraints, in the pressure-temperature (P-T) phase space, is found to be effectively a one-dimensional nonlinear problem i.e., solving a single transcendental equation. The methodology and algorithm presented herein are based on "the chemical picture," with all thermodynamic properties derived self-consistently from the free energy function, and on the mapping of the resulting set of governing equations into a one-variable zero-search. The algorithm is successful for most practical models for nonideality corrections to the free energy function, which are fully reflected in the derived nonideal Saha equations as lowering of ionization potentials, corrected equation of state, and truncated partition functions. The ease and efficiency of the introduced algorithm allows, with significant simplicity, the computations of population densities of all plasma species (neutral, ionized, and excited) up to maximum ionization states equal to the atomic numbers of the involved elements with minimal computational work. It also considers an extensive database of energy levels of the excited states. The algorithm is analytically known to be safe, fast, efficient, and solves the problem to the machine accuracy. It shows no numerical instabilities, no convergence problems, and no accuracy limitations or lack-of-change problems, which have been repeatedly reported in the literature. A nontrivial problem is worked out and presented in detail showing the effectiveness of the present methodology. For completeness, a criterion f- or the validity of the assumption of local thermodynamic equilibrium is applied to the results of the sample problem showing regions of the pressure-temperature phase space over which the assumption is valid. View full abstract»

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  • Excitation of electromagnetic waves by a current source in the inhomogeneous lossy magnetoplasma

    Publication Year: 2005 , Page(s): 1984 - 1994
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    The excitation of nonmonochromatic signals by source current and their longitudinal propagation in an inhomogeneous magnetoplasma is studied. Three types of excitation source current are considered for the study. The inhomogeneity of magneto-ionic medium is taken with respect to the variation in plasma density and strength of the magnetic field. The effect of interparticle collisions on the amplitude of the signal is studied. Properties of the excited signals are discussed in different frequency ranges in terms of charge per unit length of the excitation source and the distance of propagation of the signal. View full abstract»

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  • Small amplitude soliton propagation in a weakly relativistic magnetized space plasma: electron inertia contribution

    Publication Year: 2005 , Page(s): 1995 - 2004
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    Soliton propagation in a weakly relativistic two-fluid space related plasma is studied under the effect of an external magnetic field, and the contribution of electron inertia to the soliton characteristics is evaluated. It is found that fast and slow modes are possible in such a plasma that correspond to the propagation of compressive solitons, namely fast compressive soliton and slow compressive soliton, respectively. These solitons occur for a particular range of angle θ between the directions of wave propagation and the magnetic field, given by θ≤tan-1|{uz0-vz0+√(1+2σ)mi/me}/(vx0-ux0)$0 B. This range of the wave propagation angle depends on the temperature ratio σ(=Ti/Te), mass ratio mi/me, and x and z components ux0 and uz0 and vx0 and vz0 of the ion and electron velocities, respectively. Further, the dominance of the components of ion and electron velocities on the soliton characteristics via peak soliton amplitude, soliton width and soliton energy together with the effect of electron inertia is examined. It is also realized that both types of the solitons attain the same height, width, and energy when the electron inertia is neglected, and the effect of electron inertia is more pronounced on the propagation of the slow compressive solitons. View full abstract»

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  • Kadomtsev-petviashivili equation for the relativistic electromagnetic soliton in the collisionless electron-positron-ion plasma

    Publication Year: 2005 , Page(s): 2005 - 2010
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB) |  | HTML iconHTML  

    With an externally applied uniform magnetic field, a Kadomtsev-Petviashivili (KP) equation is derived to study the perpendicular nonlinear wave in a collisionless plasma consisting electrons, positrons, and ions for weak relativistic limit. The stationary solution was presented for the group velocity, amplitude, and width of the soliton. It is shown that both the externally imposed magnetic field and the ratio of the ion equilibrium density to the electron equilibrium density influence strongly the group velocity, amplitude, and width of the KP soliton. By using the figure analysis, we study the interaction law of the two parallel line-solitons. View full abstract»

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  • A diode design study of the virtual cathode oscillator with a ring-type reflector

    Publication Year: 2005 , Page(s): 2011 - 2016
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1448 KB) |  | HTML iconHTML  

    A numerical simulation study of the high-power microwave generation from the vircator (virtual cathode oscillator) is carried out for coaxial diode structure by using a three-dimensional particle-in-cell (PIC) code called MAGIC. The coaxial vircator has a centered annular cathode body, cathode ring and cylindrical meshed-anode in order to enlarge the active interaction region in the virtual cathode space. In order to enhance a conversion efficiency of the output microwave power, ring-type reflector was installed to coaxial-type diode structure. The simulation results show that the output microwave frequency has a narrow bandwidth and its output microwave power sensitively depends upon the position and width of ring-type reflector. The maximum output microwave power is obtained by adopting a ring-type reflector 10 mm in width and 40 mm in the distance from the intense relativistic electron beam to the ring-type reflector. The output microwave mode without a ring-type reflector is a mixture of TM and TE mode. However, the TM01 mode with its resonance frequency of 2.2 GHz is dominant for the ring-type reflector. View full abstract»

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  • An investigation of periodic waveguides with axial and azimuthal corrugations

    Publication Year: 2005 , Page(s): 2017 - 2026
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    The existing studies about the dispersion characteristics of the sinusoidal rippled wall cylindrical waveguides mostly center on one-dimensionally (1-D) corrugated waveguides. Sometimes two-dimensional (2-D) corrugated waveguides are needed to provide better selective and resonance properties not achievable with 1-D periodic structures. The authors of this paper improve the method of calculating the waveguide axially periodic by expanding the slow-wave structure's boundary function in Fourier series, so that it can be adopted in periodic waveguides with axial and azimuthal corrugations. In addition, the general dispersion equations for the investigation of 2-D periodic waveguide are presented in this paper. The advantage of the method lies in its universality, providing solution to the dispersion characteristics for most of the periodic waveguides with axial and azimuthal corrugations. By the method suggested here, the paper analyzes the dispersion characteristics and coupling impedance of a new rib-loaded disk-loaded waveguide and other periodic waveguides. View full abstract»

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  • Three-dimensional computation of reduction in Radar cross section using plasma shielding

    Publication Year: 2005 , Page(s): 2027 - 2034
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    We have performed three-dimensional (3-D) finite-difference time-domain (FDTD) simulations for calculating microwave scattering from metallic objects shielded by a plasma shroud. Such simulations are of interest for plasma-based stealth technology. The simulations yield a reasonable match with experimental measurements. A physical interpretation has also been provided for these results, in terms of the flow of electromagnetic power. Such an analysis is only possible using the detailed spatio-temporal evolution of electromagnetic fields that is provided by the FDTD method. We find that apart from absorption, the bending of waves toward regions of lower plasma density plays an important role in determining the extent of backscatter. This has major implications for plasma stealth applications, which have heretofore assumed that plasma absorption is the main mechanism. Also, bending could actually enhance radar scattering in directions oblique to the incident direction. We have also identified situations where 3-D simulations become necessary, and other situations where a composite one-dimensional simulation may be enough. This has practical relevance since it could help reduce the demand for computational resources while modeling large objects like aircraft. View full abstract»

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  • Synthesis of Pt/ZrO2 catalyst on Fecralloy substrates using composite plasma-polymerized films

    Publication Year: 2005 , Page(s): 2035 - 2045
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1936 KB) |  | HTML iconHTML  

    In a hydrogen-based energy system, fuel cells will utilize hydrogen to produce electricity while reformers produce hydrogen from infrastructure fuels, such as gasoline, diesel and natural gas. Reformers based on microchannel technology require a catalyst dispersed throughout a porous support, and the support must adhere firmly to the substrate. In this work, catalyst and support precursors were deposited via plasma enhanced chemical vapor deposition onto Fecralloy substrates, in alternate layers of plasma-polymerized platinum acetylacetonate and zirconium acetylacetonate. Non-equilibrium, inductively-coupled plasma was generated by applying radio frequency fields to a precursor vapor plume emanating from a heated sublimator crucible. After calcining the composite organic film to volatilize organic constituents, catalytically active platinum agglomerates remained supported by a matrix of zirconia. Plasma-processing took place directly in precursor vapor without added carrier gas. The intermediate organic composite film and the final synthesized platinum-loaded support adhering to the Fecralloy have been evaluated with profilometry, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and inductively coupled plasma-mass spectrometry. Cubic phase platinum and cubic phase zirconia have been detected on the Fecralloy. This material catalyzes conversion of carbon monoxide to carbon dioxide in a water gas shift (WGS) reactor in the temperature range 400°C-500°C. View full abstract»

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  • Determination of rational surface position and magnetic island width from electron cyclotron emission (ECE) radiometry in TCABR

    Publication Year: 2005 , Page(s): 2046 - 2050
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    Measurements of the electron temperature radial profile Te(r) have been performed on the Tokamak Chauffage Alfve´n Bre´silien tokamak with high radial resolution, using an electron cyclotron emission radiometer. The temperature profile shows distinct peculiarities in discrete radial regions which can be associated with the presence of magnetic islands. A method is proposed here to determine the radial positions and widths of the magnetic islands based upon measurement of the Fitzpatrick kind, not completely flattened, radial profile of the electron temperature Te(r). In combination with other well-known methods, the suggested methods can give additional possibilities for comparing experimental and theoretical results in the study of magnetic islands. View full abstract»

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  • 170-kV laser-triggered water switch experiments

    Publication Year: 2005 , Page(s): 2051 - 2059
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2816 KB) |  | HTML iconHTML  

    We report the results of experiments using a small Q-switched Nd:YAG laser at 532 and 1064 nm to trigger a 170-kV pulse-charged water switch. 1-σ jitters as low as ±1.7 ns were demonstrated; an order of magnitude improvement over the ±25-ns jitter of the switch in its self-breaking mode. At the optimum observed triggering wavelength of 532 nm, a 7-ns laser pulse gave better results than a 0.15-ns laser pulse. Time resolved optical diagnostics suggest a multistage triggering process in which the laser forms a string of point plasmas between the switch electrodes. These point plasmas expand, cool and merge, forming a vapor column between the electrodes that breaks down rapidly with low jitter. View full abstract»

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  • Design and operation of a sequentially-fired pulse forming network for non-linear loads

    Publication Year: 2005 , Page(s): 2060 - 2065
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1672 KB) |  | HTML iconHTML  

    While the construction of a linear pulse forming network (PFN) for a constant load impedance is relatively easy, the process is more difficult for a nonlinear or time-varying load. A passive PFN can certainly be synthesized for nonlinear loads, but is usually large and lacks the flexibility to be truly useful in most practical and research applications. This investigation describes the design and construction of a sequentially-fired pulse forming network (SFPFN) that maintains constant voltage and current for a nonlinear load. Operation of the SFPFN consists of charging multiple capacitor banks (or modules) to various levels and sequentially firing these banks into the load at appropriate times. The load and its characteristics determine the module charge voltage. An added benefit with the SFPFN is real-time computer monitoring and control allowing the PFN modules to be charged from a single prime power source via a group of switching relays. The nonlinear load used in this investigation is a helical coil electromagnetic launcher (HCEL). The SFPFN is also tested with a linear load consisting of a pulsed field coil. The nonlinearity of the HCEL is well-known with a factor of 2 change in winding resistance due to joule heating and a large variation in terminal voltage due to changes in the armature back-voltage. Experimental measurements show the SFPFN can deliver a relatively constant current pulse on the order of 5-15 kA into the HCEL load for a pulse length up to 8 ms. The maximum SFPFN operating voltage is 900 V with a total stored energy of 125 kJ. Scaling the SFPFN to larger or smaller pulse amplitudes or lengths is possible. View full abstract»

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  • Explore IEL IEEE's most comprehensive resource

    Publication Year: 2005 , Page(s): 2066
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  • 2005 Index

    Publication Year: 2005 , Page(s): 2067 - 2115
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  • Celebrating the vitality of technology the Proceedings of the IEEE [advertisement]

    Publication Year: 2005 , Page(s): 2116
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  • IEEE Transactions on Plasma Science Information for authors

    Publication Year: 2005 , Page(s): c3
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IEEE Transactions on Plasma Sciences focuses on plasma science and engineering, including: magnetofluid dynamics and thermionics; plasma dynamics; gaseous electronics and arc technology.

 

 

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