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Plasma Science, IEEE Transactions on

Issue 2 • Date Feb. 2012

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Displaying Results 1 - 25 of 26
  • Table of contents

    Publication Year: 2012 , Page(s): C1 - 413
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  • IEEE Transactions on Plasma Science publication information

    Publication Year: 2012 , Page(s): C2
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  • Influence of Thermal and Collisional Effects on the Dielectric Permittivity Tensor in a Multi Layer Plasma Waveguide With Elliptical Cross Section

    Publication Year: 2012 , Page(s): 414 - 420
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    In this paper, effects of the thermal, collisional, and the inhomogeneity for density of charged particles on the dielectric permittivity tensor in the long column of multilayer magnetized plasmas with confocal elliptical cross sections are investigated. The dielectric permittivity tensor elements and the generalized field equations of each region will be obtained. It will be shown that the permitivity tensor of each region can be written as sum of three parts: cold, collisional, and thermal. The field equations for hybrid modes in each region of the inhomogeneous warm plasma with coaxial elliptical cylinder boundaries are presented. View full abstract»

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  • A Hybrid Model to Predict Electron and Ion Distributions in Entire Interelectrode Space of a Negative Corona Discharge

    Publication Year: 2012 , Page(s): 421 - 428
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    Atmospheric direct current (dc) corona discharge from thin wires or sharp needles has been widely used as an ion source in many devices such as photocopiers, laser printers, and electronic air cleaners. Existing numerical models to predict the electron distribution in the corona plasma are based on charge continuity equations and the simplified Boltzmann equation. In this paper, negative dc corona discharges produced from a thin wire in dry air are modeled using a hybrid model of modified particle-in-cell plus Monte Carlo collision (PIC-MCC) and a continuum approach. The PIC-MCC model predicts densities of charge carriers and electron kinetic energy distributions in the plasma region, while the continuum model predicts the densities of charge carriers in the unipolar ion region. Results from the hybrid model are compared with those from prior continuum models. Superior to the prior continuum model, the hybrid model is able to predict the voltage-current curve of corona discharges. The PIC-MCC simulation results also suggest the validity of the local approximation used to solve the Boltzmann equation in the prior continuum model. View full abstract»

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  • Low-Frequency Instabilities in the Interaction of Ion Beam With Magnetized Plasma

    Publication Year: 2012 , Page(s): 429 - 437
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    The low-frequency instabilities in the interaction between an ion beam and a magnetoactive plasma are investigated taking into account the effects of the dissipation and thermal motion of the charged particles. Furthermore, the effects of magnetic field strength, ion beam velocity, and propagation angle on the resonance frequency and the growth rate of the instabilities are studied. It is shown that, according to the strength of the magnetic field and the ion beam velocity, the increase of the thermal velocity of the charged particles can increase or decrease the resonance frequency in the ion acoustic frequency range. View full abstract»

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  • Temporal Evolution of the Pulsed Positive Streamer Discharge in Water

    Publication Year: 2012 , Page(s): 438 - 442
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (545 KB) |  | HTML iconHTML  

    The temporal evolution of the pulsed positive streamer discharge in water is investigated by high-speed photography. Four successive one-shot photographs were acquired from the same discharge pulse. Two modes of streamer propagation, called the first mode and the second mode, were confirmed from the time-resolved images. The first-mode streamer appears as an expanding luminous plasma ball, and no filament can be recognized at this stage. The standing time and the maximum radius of the luminous plasma ball are 40-60 ns and 600-800 μm, respectively. Then, the streamer transits to the second mode, in which many luminous filaments grow up from the plasma ball. At the beginning of the second mode, all the filaments propagate isotropically from the plasma ball and have an equal propagation velocity. Only some of the filaments originated from the plasma ball can propagate furthermore, and most of them spontaneously disappear in about 40 ns. After it reaches the stopping length, the streamer stops propagating but remains luminous. As the discharge voltage drops down, the brightness of the streamer decreases, and the light shrinks successively from the streamer head to the tip of the point anode. Our measured propagation velocity for the first mode is about 25 km/s. The propagation velocity increases about two times as the streamer transits from the first mode to the second mode and then reduces approximately to the same value for the first mode. The water conductivity has no significant influence on the propagation velocity within the range studied. View full abstract»

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  • Self-Consistent Nonlinear Theory and Simulation of Gyro-TWT With Helically Corrugated Waveguide

    Publication Year: 2012 , Page(s): 443 - 450
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (443 KB) |  | HTML iconHTML  

    We present the transmission equations and dispersion equations of a helically corrugated waveguide according to the coupling wave theory and the impedance perturbation method. We analyzed the field distribution of the helically corrugated waveguide according to the dispersion equations. We developed the self-consistent nonlinear equations of beam-wave interaction through studying the self-consistent nonlinear theory of beam-wave interaction in a gyrotron traveling-wave tube with a helically corrugated waveguide. We analyzed the dispersion equations and simplified, numerically calculated, and simulated the beam-wave interaction equations. View full abstract»

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  • Statistical Prediction of Microwave Window Breakdown: Effects of RF Magnetic Field

    Publication Year: 2012 , Page(s): 451 - 462
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (375 KB) |  | HTML iconHTML  

    This paper analyzes the effects of RF magnetic field on the initiation and temporal evolution of multipactor discharge on a dielectric exposed to a linearly polarized electromagnetic wave. It is revealed that the RF magnetic field changes considerably the electron dynamics in the range of small dc fields: It leads to a widening of the susceptibility region and gives the dominant contribution to the total buildup time of the discharge. The nonlinear integral equation for obtaining the saturation level for the given material and velocity spread is formulated. View full abstract»

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  • A Novel V-Shaped Microstrip Meander-Line Slow-Wave Structure for W-band MMPM

    Publication Year: 2012 , Page(s): 463 - 469
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (783 KB) |  | HTML iconHTML  

    In this paper, a novel V-shaped microstrip meander-line slow-wave structure (SWS) is proposed for use in a low-voltage high-efficiency wide-bandwidth miniature millimeter-wave traveling-wave tube (TWT). The electromagnetic characteristics and the interaction between the sheet electron beam and slow wave in this SWS are obtained by utilizing the CST Microwave Studio and Particle Studio codes, respectively. From our calculations, it is predicted that, at a beam voltage of 3.7 kV and a beam current of 100 mA, an output power greater than 30 W can be obtained ranging from 75 to 100 GHz, and this V-shaped microstrip meander-line TWT will be helpful for a W-band millimeter-wave power module. View full abstract»

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  • Fundamentals of Slot Antenna Designing for Application in Surface Wave Plasma Sources

    Publication Year: 2012 , Page(s): 470 - 480
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2232 KB) |  | HTML iconHTML  

    Different aspects of slot antenna designing for application in large-scale flat surface wave plasma (SWP) sources are discussed. Finite difference time domain simulation method is applied to investigate radiation characteristics of different slot antenna structures. The effects of slot width and location, and waveguide wall thickness on antenna radiation are studied. Using the transmission line theory, optimum thicknesses for waveguide walls are offered. The vertical, longitudinal, and compound structures of slot antenna arrays are analyzed, and their efficiencies are compared for producing SWPs. View full abstract»

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  • Energy Transformations in Column of Plasma-Focus Discharges With Megaampere Currents

    Publication Year: 2012 , Page(s): 481 - 486
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    Energy transformations are estimated from experimental results obtained on the PF-1000 plasma focus facility operated with a deuterium gas filling and maximum current of 2 MA, which enabled the neutron yield of >; 1011 to be obtained. Use was made of the laser interferometry images and the recorded signals of hard X-rays (HXRs) and neutrons, as well as voltage, current, and current-derivative waveforms. The calculations of the inductance, derivative of inductance, and resistance of the current sheath enabled the evaluation of energy delivered to the plasma. It was estimated that, during the intensive pulses of the HXRs and neutrons, energy of 3-11 kJ is delivered to the plasma column probably through an anomalous resistance at the time closely before and during pulses of HXR and neutron production. A predominant portion of this energy is effectively used for the acceleration of fast deuterons capable of producing fusion neutrons. View full abstract»

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  • Surface Treatment of Polyethylene Terephthalate Using Plasma Ion Implantation Based on Direct Coupling of RF and High-Voltage Pulse

    Publication Year: 2012 , Page(s): 487 - 491
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    Plasma immersion ion implantation employing hybrid radio-frequency (RF) and high-voltage (HV) pulses via a single feedthrough is an effective surface modification method. In this technique, the sample holder is connected to both the RF generator and the HV modulator in order to generate a high-density plasma in the vicinity of the sample. HV pulses are applied to the sample in between the RF pulses to conduct ion implantation. Polyethylene terephthalate (PET) samples were modified using an C2H2 plasma generated by this technique, and diamond-like-carbon films were successfully deposited. In this process, the pulsed HV changed from 2.5 to 10 kV with an RF power ranging from 0 to 150 W and an RF of 13.56 MHz. The C2H2 gas pressure was maintained at 1.0 Pa with a processing time of 15 min. Cleaning effects were observed without arcing damage with increasing sample bias from 2.5 to 10 kV. The negative bias and RF were observed to influence the water contact angles of treated PET samples. The plasma-implanted surface became more hydrophilic with increasing sample bias and RF power, respectively. View full abstract»

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  • A Novel Plasma Technique for Surface Treatment: The Plasma Expander

    Publication Year: 2012 , Page(s): 492 - 496
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (271 KB) |  | HTML iconHTML  

    This paper describes a new plasma treatment method: the plasma expander. In this approach, expanding shock waves are generated in a vacuum chamber by pulsed plasmas. Collisions of fast species in the waves modify the properties of solid surfaces exposed to the plasma. The degree of such modification is governed by the energy delivered by the plasma exposure. To confirm the efficacy of this approach, modifications induced in the properties of thin polymer films produced by plasma-enhanced chemical vapor deposition by exposure to nitrogen plasma shock waves were investigated. The films were prepared from benzene radio frequency plasmas and subsequently exposed to different quantities of nitrogen shock waves Nw. The effects of Nw on the wettability, molecular structure, and mechanical properties of the films were studied. Fourier transform infrared spectroscopy revealed that greater Nw resulted in the loss of C-H groups and the rupture of benzene aromatic rings observed in the structure of the as-deposited films. Furthermore, the contact angle strongly increased and the hardness, evaluated by nanoindentation, increased up to fourfold with the increase in the intensity of the treatment. View full abstract»

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  • Numerical investigation of the swirl gas angle and arc current dependence on evaporation of hafnium cathode in a plasma cutting arc

    Publication Year: 2012 , Page(s): 497 - 504
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (521 KB) |  | HTML iconHTML  

    The effects of arc current and swirl gas angle on a plasma cutting arc are investigated using a 2-D thermofluid model developed for arc plasma with consideration of hafnium (Hf) cathode evaporation. Numerical modeling is extremely important to predict the erosion amount of Hf cathode for different process parameters in plasma cutting arcs. Results show that a larger swirl gas angle causes a high-temperature plasma area in front of the cathode surface shrunken in the radial direction and that the flow patterns changed to the opposite direction in front of the cathode at swirl gas angles from 12° to 30°. This change in the gas flow pattern induces Hf vapor transport along the center-axis direction to the nozzle outlet. With the increase of arc current, the whole temperature field markedly increases, and the radius of arc plasma is expanded in the radial direction. The total amount of mass loss of Hf cathode evaporation was predicted to be enhanced with increasing arc current and swirl gas angle from 12°. View full abstract»

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  • Calculation of Turn Skipping Losses in Helical Flux Compression Generators

    Publication Year: 2012 , Page(s): 505 - 510
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    In helical flux compression generators, the ohmic and intrinsic flux losses limit severely the performance of them. One of the sources of intrinsic flux losses is the turn skipping flux loss. This paper first introduces an accurate criterion for the prevention of the turn skipping phenomenon in these generators. Then, a novel method is presented to calculate the flux loss due to this phenomenon. In addition, an equivalent resistance is introduced to consider the effect of turn skipping flux loss on the generator performance. The calculation results show that, as soon as the turn skipping occurs, about 30% of a turn flux is lost and this value is increased rapidly with eccentricity increasing. Therefore, it is necessary to prevent this phenomenon as far as possible. The calculated output current of the simulated generator also shows that the maximum current when considering the turn skipping loss is about 15% of the maximum current in the case of ignoring it. Based on the authors' knowledge, quantification of the turn skipping flux losses has not been presented previously in the open literature. View full abstract»

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  • Investigation of the Load Current Tail Phenomenon on the Qiangguang Generator

    Publication Year: 2012 , Page(s): 511 - 518
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    The phenomenon of load currents with long decaying tails can be found on many pulsed-power generators, such as the Z accelerator at Sandia National Laboratories in the U.S. and the Angara-5-1 facility in Russia. In this paper, the reasons that cause the load current tail on the Qiangguang generator are investigated. The experiments were carried out using two insulator stacks with different diameters and insulator ring numbers. The results show that the current tail on the Qiangguang generator is not caused by measurement error but rather by electrical flashover across the surface of the insulator stack and by leakage current through the water between the stack and the outer wall of the water-filled transmission line that feeds the vacuum section on the Qiangguang generator. Also, an equivalent circuit for the Qiangguang generator was constructed and used in PSpice simulations. By adding a time-dependent resistance in parallel with the load, the simulations were able to produce current waveforms that closely match those recorded during experiments. In additional experiments, an optical fiber was used with a photoelectric cell to collect the flashover light emitted from the surface of the vacuum-insulator rings. The data collected show that the fiber signal and the beginning of the load current tail are time correlated. More recently, a new insulator stack made of Rexolite was acquired and used in yet more experiments. The results of these experiments show that, by using the new insulator stack, the onset of the load current tail phenomenon is significantly delayed. The data from all of the experiments show that stack flashover is the main cause of the load current tail on the Qiangguang generator. View full abstract»

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  • Analytical Modeling and Design Optimization of Linear Synchronous Motor With Stair-Step-Shaped Magnetic Poles for Electromagnetic Launch Applications

    Publication Year: 2012 , Page(s): 519 - 527
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1294 KB) |  | HTML iconHTML  

    In this paper, a stair-step-shaped magnetic pole structure is proposed to use in a permanent-magnet linear synchronous motor (PMLSM) for its application in an electromagnetic launch system. The aim of this configuration is to shape the air-gap flux density distribution produced by poles to be as close to a sine waveform as possible for the reduction of thrust ripple and the increase of motor controllability. An analytical model is derived for the PMLSMs by solving Maxwell equations and applying the superposition theorem for calculating the magnetic field, electromotive force, and thrust/torque of the motor. Magnet dimensions are then optimized using the analytical method and genetic algorithm, where the reduction of air-gap flux density harmonics is considered as the optimization target. Finally, the effectiveness of the proposed technique to enhance the motor performance is investigated by a time-stepping transient finite-element method. The results show an improvement in the optimal motor performance. View full abstract»

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  • Experimental Investigation on the Initial Expansion Process in a Drawn Vacuum Arc and the Influence of Axial Magnetic Field

    Publication Year: 2012 , Page(s): 528 - 534
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1061 KB) |  | HTML iconHTML  

    The initial expansion process in a drawn vacuum arc and the influence of axial magnetic field (AMF) were investigated experimentally in a demountable vacuum chamber. Arc characteristics were investigated with the aid of a high-speed digital camera with an exposure time of 2 μs . In a drawn vacuum arc, the arc sequence begins with the bridge column arc formed after the rupture of the molten metal bridge. This column evolves into the transition mode, which consisted of a central column with few or no cathode spots (CSs) outside the column, and then into the fully diffuse mode. Experimental results indicated that in transition mode arc, the expansion process could be characterized by the appearance of CSs outside the central column, and could be classified into two patterns, “slow” expansion and “quick” expansion according to the characteristics of the formation and motion of new CSs (conducting channels) outside the central column of arc. The influence of AMF and its distribution on the expansion process was also investigated. Investigation results indicated that AMF had two contrary effects, i.e., inhibiting effect and prompting effect, on the initial expansion stage of drawn vacuum arc. Furthermore, saddle-shaped AMF could encourage the arc transition into diffuse mode more effectively than bell-shaped AMF. View full abstract»

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  • Propane Oxidation in a Plasma Torch of a Low-Current Nonsteady-State Plasmatron

    Publication Year: 2012 , Page(s): 535 - 542
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    This paper describes the plasma-assisted combustion system intended to generate a torch flame with a high power density per unit area. In the system, a kind of hybrid concept is proposed. A primary unit for combustion sustaining is a low-current nonsteady-state plasmatron with a low level of electric power. The plasmatron activates an air/hydrocarbon mixture and sustains the oxidation processes in the plasma torch. In turn, the heat power of the torch sustains the main burning process in the torch flame. The results of experiments on propane oxidation in the plasma torch of plasmatron in a wide range of equivalence ratio are presented. As applied to the combustion system design, the plasma torch can provide both the complete and the partial propane oxidation with syngas generation. View full abstract»

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  • Special issue on atmospheric pressure plasma jets and their applications

    Publication Year: 2012 , Page(s): 543
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  • Special issue on nonthermal medical/biological applications using ionized gases and electromagnetic fields

    Publication Year: 2012 , Page(s): 544
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  • Special issue on Z-pinch plasmas

    Publication Year: 2012 , Page(s): 545
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  • Proven powerful [advertisement]

    Publication Year: 2012 , Page(s): 546
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  • 2012 IEEE membership form

    Publication Year: 2012 , Page(s): 547 - 548
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  • IEEE Transactions on Plasma Science information for authors

    Publication Year: 2012 , 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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