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Plasma Science, IEEE Transactions on

Issue 2 • Date April 2006

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  • Table of contents

    Publication Year: 2006 , Page(s): c1 - 129
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  • IEEE Transactions on Plasma Science publication information

    Publication Year: 2006 , Page(s): c2
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  • Guest Editorial Special Issue on Plenary and Invited Papers From ICOPS 2005

    Publication Year: 2006 , Page(s): 130 - 131
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  • Electron cross-field transport in a miniaturized cylindrical Hall thruster

    Publication Year: 2006 , Page(s): 132 - 141
    Cited by:  Papers (9)
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    Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. The present paper gives a review of the experimental and numerical investigations of electron cross-field transport in the 2.6-cm miniaturized cylindrical Hall thruster (100-W power level). We show that, in order to explain the discharge current observed for the typical operating conditions, the electron anomalous collision frequency νB has to be on the order of the Bohm value, νB ≈ ωc/16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The optimal regimes of thruster operation at low background pressure (below 10-5 torr) in the vacuum tank appear to be different from those at higher pressure (∼10-4 torr). View full abstract»

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  • Lateral motion of a dust particle in magnetized plasma sheath

    Publication Year: 2006 , Page(s): 142 - 148
    Cited by:  Papers (10)
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    In this paper, lateral mobilization of a dust particle through application of an oblique magnetic field in a plasma sheath with infinitely long lateral dimensions is studied. A weakly collisional two-fluid model is implemented to simulate the plasma. A single submicrometer-sized particle is released at the sheath edge with zero initial velocity and is tracked in Lagrangian frame, taking into account various forces. Various characteristics of the particle lateral motion such as time history of its horizontal position, velocity, and acceleration components are presented and discussed. Through investigation of power spectra of plasma and particle variables, the particle drift in the horizontal plane is explained. While varying parameters such as magnetic field intensity, particle density, and its radius, the particle horizontal velocity components are calculated. The variation of these velocity components is then explained by considering the ion velocity components at the particle location. View full abstract»

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  • Grid-free plasma Simulation techniques

    Publication Year: 2006 , Page(s): 149 - 165
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1920 KB) |  | HTML iconHTML  

    A common approach to modeling kinetic problems in plasma physics is to represent the plasma as a set of Lagrangian macro-particles which interact through long-range forces. In the well-known particle-in-cell (PIC) method, the particle charges are interpolated to a mesh and the fields are obtained using a fast Poisson solver. The advantage of this approach is that the electrostatic forces can be evaluated in time O(NlogN), where N is the number of macro-particles, but the scheme has difficulty resolving steep gradients and handling nonconforming domains unless a sufficiently fine mesh is used. The current work describes a grid-free alternative, the boundary integral/treecode (BIT) method. Using Green's theorem, we express the solution to Poisson's equation as the sum of a volume integral and a boundary integral which are computed using particle discretizations. The treecode replaces particle-particle interactions by particle-cluster interactions which are evaluated by Taylor expansions. In addition, the Green's function is regularized and adaptive particle insertion is implemented to maintain resolution. Like PIC, the operation count is O(NlogN), but BIT avoids using a regular grid, so it can potentially resolve steep gradients and handle complex domains more efficiently. We applied BIT to several bounded plasma problems including a one-dimensional (1-D) sheath in direct current (dc) discharges, 1-D virtual cathode, cold two-stream instability, two-dimensional (2-D) planar and cylindrical ion optics, and particle dynamics in a Penning-Malmberg trap. Some comparisons of BIT and PIC were performed. These results and ongoing work will be reviewed. View full abstract»

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  • Experimental and theoretical results with plasma antennas

    Publication Year: 2006 , Page(s): 166 - 172
    Cited by:  Papers (40)
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    This report is a summary of an extensive research program on plasma antennas. We have found that plasma antennas are just as effective as metal antennas. In addition, they can transmit, receive, and reflect lower frequency signals while being transparent to higher frequency signals. When de-energized, they electrically disappear. Plasma noise does not appear to be a problem. View full abstract»

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  • High-power gyrotron development at Forschungszentrum Karlsruhe for fusion applications

    Publication Year: 2006 , Page(s): 173 - 186
    Cited by:  Papers (13)
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    In the first part of this paper, the status of the 140-GHz continuously operated gyrotrons with an output power of 1 MW for the stellarator Wendelstein 7-X will be described. With the first series tube, an output power of 1000 kW has been achieved in short pulse operation (milliseconds) with an electron beam current of 40 A, and of 1150 kW at 50 A. With a pulse length of 3 min limited by the available high-voltage (HV) power supply, an output power of 920 kW at an electron beam current of about 40 A with an efficiency of 45% and a mode purity of 97.5% has been obtained. At a reduced beam current of 29 A, an output power of 570 kW was measured with a pulse length of 1893 s without significant increase in tube pressure. The energy content of this pulse is almost 1.1 GJ. For the next fusion plasma device, International Thermonuclear Experimental Reactor (ITER), gyrotrons with a higher output power of about 2 MW are desirable. In short-pulse experiments, the feasibility of the fabrication of coaxial cavity gyrotrons with an output power up to 2-MW, continuous wave (CW), has been demonstrated, and the information necessary for a technical design has been obtained. The development of a long-pulse 2-MW coaxial cavity gyrotron started within a European cooperation. In parallel to the design and fabrication of an industrial prototype gyrotron, a short-pulse preprototype gyrotron has been operated to verify the design of critical components. An output power of 1.2 MW with an efficiency of 20% has been achieved. The development of frequency tunable gyrotrons operating in the range from 105 to 140 GHz for stabilization of current driven plasma instabilities in fusion plasma devices (neoclassical tearing modes) is another task in the development of gyrotrons at the Forschungszentrum Karlsruhe. View full abstract»

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  • Three-dimensional theory and simulation of nonrelativistic elliptic electron and Ion beam generation

    Publication Year: 2006 , Page(s): 187 - 193
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    A three-dimensional theory of nonrelativistic, laminar, space-charge-limited, ellipse-shaped, charged-particle beam formation has been developed recently. Charged particles (electrons or ions) are accelerated across a diode by a static voltage differential and focused transversely by Pierce-type external electrodes placed along analytically specified surfaces. The theory is presented here along with design examples for a 6:1 elliptic electron beam diode and a 3:2 heavy ion beam diode. OMNITRAK simulations are performed to verify the theory and to explore beam tolerances with respect to perturbations of the diode geometry of the sort likely to be encountered in a realistic device: finite electrode extent, part misalignment, and allowances for thermal isolation. View full abstract»

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  • Radiation properties and implosion dynamics of planar and cylindrical wire arrays, asymmetric and symmetric, uniform and combined X-pinches on the UNR 1-MA zebra generator

    Publication Year: 2006 , Page(s): 194 - 212
    Cited by:  Papers (21)
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    In the following experiments, we studied implosions of different wire arrays and X-pinches produced on the 1-MA Zebra generator at the University of Nevada, Reno. Diagnostics included both spatially-resolved and time-gated X-ray imaging and spectroscopy, and laser probing. In particular, we compared planar wire arrays, to which little energy could be coupled via the conventional magnetic-to-kinetic conversion mechanism, to cylindrical wire arrays of comparable dimensions and mass. The planar wire arrays were shown to radiate much higher peak power and more energy in subkiloelectronvolt and kiloelectronvolt spectral ranges than cylindrical wire arrays. We tested the theoretical conjecture that enhanced resistivity due to the small-scale inhomogeneity of wire-array plasmas has a major effect on dynamics, energy coupling and radiation performance of wire-array Z-pinches. The study of Al, Alumel, and W cylindrical wire arrays shows a wide variety of characteristic behaviors in plasma implosions discussed hereinafter. Additional experimental results for symmetric and asymmetric, uniform stainless steel, Cu, Mo, combined Al/Mo, Mo/Al, Al/W, W/Al, and Mo/W X-pinches are also presented. New data for the total radiation yield are obtained. The planar structures of X-pinch plasma and the corresponding electron beam was observed for most of X-pinches. The generation of hot spots along original wires positions-cooler than those from the cross-wire region-and arc structures with hot spots between wires were found for X-pinches composed from Al, Cu, and W wires. View full abstract»

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  • Monochromatic X-ray self-emission imaging of imploding wire array Z-pinches on the Z accelerator

    Publication Year: 2006 , Page(s): 213 - 222
    Cited by:  Papers (6)
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    A monochromatic X-ray self-emission imaging diagnostic has been developed for the Z accelerator, which drives 20 MA in 100 ns to implode wire array Z-pinches, generating up to 250 TW of soft X-ray radiation. This instrument reflects eight pinhole images from a flat Cr/C multilayer mirror (MLM) onto a 1-ns time-resolved microchannel plate detector. The MLM reflects 277-eV photons with ∼5-eV bandwidth and 20% peak reflectivity, and an aluminized parylene filter shields the detector from visible light. High-energy bremsstrahlung X-rays do not follow the reflected beam path, and so the background on the shielded detector is reduced compared to a standard pinhole camera. The MLM-reflected images offer low-photon-energy spectral resolution that filtration alone cannot, yielding high-quality images of the final stages of the Z-pinch implosion. Initial data on Z from a Cu wire array will be presented. Observed phenomena include implosion instabilities, zippered implosion of a piston onto a precursor column during the onset of stagnation, accretion of trailing colder mass during the X-ray pulse, and cathode reemission. The inferred implosion velocity is significantly less than thin-shell implosion model calculations, and well below what is required for efficient Cu K-shell radiation. Instability-dominated, bright-spot Cu K-shell emission is seen on a second adjacent eight-frame filtered pinhole camera that is in the same beamline. View full abstract»

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  • High-density field-reversed configuration plasma for magnetized target fusion

    Publication Year: 2006 , Page(s): 223 - 228
    Cited by:  Papers (7)
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    Field reversed theta pinch technology is employed with programmed cusp fields at the theta coil ends to form high-density field-reversed configuration (FRC) plasmas. The well-formed FRC plasmas have volume-averaged density of 2-4×1022 m-3, total temperature (Te+Ti) of 300-500 eV, and plasma lifetime between 10-20 μs in 50-70 mtorr of deuterium static gas fill. The achieved FRC parameters are very close to the desired target plasma requirements for magnetized target fusion. View full abstract»

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  • Phase contrast imaging of waves and instabilities in high temperature magnetized fusion plasmas

    Publication Year: 2006 , Page(s): 229 - 234
    Cited by:  Papers (17)
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    Phase contrast imaging (PCI) is an internal reference beam interferometry technique which provides a direct image of line integrated plasma density fluctuations. The method has been used with great success to measure waves and turbulence in magnetically confined high temperature plasmas. The principle of PCI was developed in optics in the 1930s by the Dutch physicist Zernike, leading to the development of phase-contrast microscopy. The technique allows one to detect the variation of the index of refraction of a dielectric medium (such as a plasma) due to the presence of waves or turbulent fluctuations. The image produced by the introduction of a phase plate in the beam path, and subsequently imaging the expanded laser beam onto a detector array can be used to calculate wavelengths and correlation lengths of fluctuations in high temperature plasmas. In this paper, the principle of PCI is summarized and examples of measurements from the DIII-D and Alcator C-Mod tokamak plasmas are given. View full abstract»

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  • Molar ratio and energy efficiency of DeNOx using an intermittent DBD ammonia radical injection system

    Publication Year: 2006 , Page(s): 235 - 241
    Cited by:  Papers (7)
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    Ammonia radicals are produced by a dielectric barrier discharge (DBD) in a chamber, called radical injector, which is separate from the chamber that NO gas flows. The radicals are injected into the mixing zone in NO gas flow field to decompose NO gas. The power source for generating the DBD is a one cycle sinusoidal (OCS) waveform so as to easily control the electrical power consumed in the DBD plasma. The fundamental frequency of the OCS power source is 150 kHz. Based on the molar ratio of ammonia particles to NO particles in a unit time, NO removal characteristics were discussed. By increasing the DBD consumed energy, the molar ratio approaches 1 showing the stoichiometric DeNOx by NH2 radicals. A high energy efficiency is found by reducing the consumed energy in the radical injector, where the molar ratio is higher than 1. In this case, the excess ammonia gas without converting into ammonia radicals in the radical injector is directly injected into the reaction zone, and contributes to decompose the NO gas. Oxygen gases with a concentration from 5% to 15% included in the NO gas significantly contribute to decompose NO gases, which brings a decomposition of NO with a low molar ratio. View full abstract»

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  • Microparticle probes for laboratory plasmas

    Publication Year: 2006 , Page(s): 242 - 248
    Cited by:  Papers (10)
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    Two applications of microparticles (micron-size particles) for laboratory plasma diagnosis are discussed. The first application is about injecting hypervelocity microparticles [(HDI) for hypervelocity dust injection] for internal magnetic field measurement in high-temperature plasmas. Since the concept of HDI has already been examined in details in our previous works, the primary focus here is to compare different schemes of microparticle acceleration. A new design of HDI based on plasma-dynamic accelerator is described to inject multiple microparticles to velocities around 10 km/s simultaneously. The other application is about using microparticles to measure plasma flow [(mPTV) for microparticle tracer velocimetry]. Directions of plasma flow at multiple locations can be measured simultaneously using mPTV because ion drag dominates over other forces inside laboratory plasmas of order 1019 m-3 in density and a few electron volts in temperature. In addition to complex interactions between a microparticle with plasma, the magnitude of plasma flow may not be obtained directly from the microparticle velocity because of the time it takes for each microparticle to relax to local plasma velocity. In summary, microparticles are naturally small objects in all three dimensions and can, therefore, become useful diagnostics for laboratory plasmas with minimal perturbation. View full abstract»

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  • Direct measurements of the dynamics of self-guided femtosecond laser filaments in air

    Publication Year: 2006 , Page(s): 249 - 253
    Cited by:  Papers (6)
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    Imaging of femtosecond laser filaments is accomplished by utilizing a recently developed diagnostic which is not damaged by the filaments and which greatly reduces the nonlinearities in the detection system. This calibrated detection system allows quantities such as the filament energy and fluence distribution to be determined with greater detail, accuracy, and confidence than was previously possible. The diagnostic is placed on a rail so that filament images can be obtained at a large number of positions along the propagation path. It is found that filaments formed from 450-fs pulses carry higher fluence and propagate farther than filaments formed from 50-fs pulses. View full abstract»

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  • Three-dimensional modeling of a direct current operated Hg-Ar lamp

    Publication Year: 2006 , Page(s): 254 - 262
    Cited by:  Papers (8)
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    This paper describes a three-dimensional (3-D) numerical model, first of its kind, for predicting the plasma behavior of high pressure (viz. high-intensity discharge (HID) and ultra high pressure) lamps. Two-dimensional (2-D) and axisymmetric plasma models are widely used as these are less complicated and fairly available. But 2-D and axisymmetric models are not useful for any lamp operation other than vertical burning. There are many systems where HID lamps are horizontally oriented and/or inclined. Therefore, a universal 3-D model is a must for the proper predictions of such lamp behavior. The developed plasma model solves the complete set of magnetohydrodynamic (MHD): transport equations of mass, momentum, and energy along, with the vector potential form of Maxwell's equations to account for the electromagnetic effects. Radiation of the energy balance is calculated using the P-1 radiation method by dividing the electromagnetic spectrum into several graybands. For presenting the model performance, calculations are done for a lamp having arbitrary geometry and operating conditions. The glass-bulb of the lamp is assumed ellipsoid and the interelectrode gap is taken as 5 mm. Although the model has the features of predicting properties of the whole domain (electrodes with nonequilibrium cathode-sheath, 3-D plasma region, 2-D glass bulb, and stems), we limit the presentation for the electrodes and plasma region only to control the article size. Operating conditions of the lamp are chosen as a direct current (dc) of 20 A, a discharge medium of Hg and Ar mixture, and an operating pressure of 0.11 MPa. Current levels of 30 and 40 A have also been used to predict the current effect on radiation output. Calculated plasma results show a clear deviation from axisymmetry for horizontal operation of the lamp. Temperature and other plasma fields are found as the strongest near the cathode tip. Effect of Lorentz forces on the plasma velocity is found very significant. For the case of 20 A, maximum temperature is found as about 11000 K and the maximum velocity as 6 m/s. View full abstract»

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    Publication Year: 2006 , Page(s): 263
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    Publication Year: 2006 , Page(s): 264
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  • IEEE Transactions on Plasma Science Information for authors

    Publication Year: 2006 , Page(s): c3
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Aims & Scope

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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Meet Our Editors

Editor-in-Chief
Steven J. Gitomer, Ph.D.
Senior Scientist, US Civilian Research & Development Foundation
Guest Scientist, Los Alamos National Laboratory
1428 Miracerros Loop South
Santa Fe, NM  87505  87505  USA
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