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Plasma Science, IEEE Transactions on

Issue 6 • Date Dec. 2004

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Displaying Results 1 - 23 of 23
  • Table of contents

    Publication Year: 2004 , Page(s): c1
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  • IEEE Transactions on Plasma Science publication information

    Publication Year: 2004 , Page(s): c2
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  • Slow cyclotron instability in a high-power backward-wave oscillator

    Publication Year: 2004 , Page(s): 2157 - 2168
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    The linear dispersion relation of a backward-wave oscillator (BWO), derived earlier by the authors, is modified to include effects of RF surface current at the beam-vacuum interface. This modified dispersion relation results in an unstable interaction between the slow cyclotron mode (SCM) and the structure mode in addition to the conventional Cherenkov instability caused by the slow space charge mode. Numerical analysis is then carried out using parameters of a BWO experiment at University of Maryland. Fine structure of the SCM instability is elucidated. The analysis indicates that BWO radiation would not be suppressed near cyclotron absorption in an infinitely long system. View full abstract»

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  • Magnetically driven Rayleigh-Taylor instability with acceleration gradient

    Publication Year: 2004 , Page(s): 2169 - 2174
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    We investigate the stability properties of a slab of accelerating, current-carrying, cold, fluid when the accelerating J_ × B_ force is nonuniform throughout the slab and leads to a gradient in the slab acceleration. A nonuniform force that squeezes (stretches) the slab while accelerating it increases (decreases) the Magnetic-Rayleigh-Taylor instability growth rate. This effect can explain recent experiments on thin, magnetically driven, imploding liner shells. View full abstract»

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  • Ferro-electric pellet shape effect on C2F6 removal by a packed-bed-type nonthermal plasma reactor

    Publication Year: 2004 , Page(s): 2175 - 2183
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB) |  | HTML iconHTML  

    Ceramic dielectric material pellet shape effects on the performance of perfluoroethane (C2F6) gas removal from simulated semiconductor process gas using packed-bed reactor are experimentally investigated. The bench-scale cylindrical shaped (plasma part: 30-mm inner diameter and 20-mm length) plasma reactor consists of two metal mesh electrodes packed with spherical, cylindrical, or hollow cylindrical shaped ferro-electric pellets with various dielectric constants. The 60-Hz ac high voltage was applied to the mesh electrode. The 3000 ppm C2F6 gas diluted with nitrogen was used as simulated gas with flow rate of 30 mL/min. The C2F6 concentration was monitored using Fourier transform Infrared absorption spectroscopy measurements. The results show that the packed-bed plasma reactor with the hollow cylindrical-shaped pellets removed the C2F6 gas with energy efficiency of 3.7 g/kWh. This value was almost 1.5 times higher than the efficiency 2.5 g/kWh in case of the spherical pellets. The discharge characteristics in the reactor were also changed with the pellet shape. The discharge onset voltage decreases by changing the pellets shape from sphere to hollow cylinder. The quantity of charges accumulated with the microdischarge currents increases by changing the pellet shape from sphere to hollow cylinder in spite of fact that the energy consumed in the reactor decreases. View full abstract»

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  • Effect of attenuation on backward-wave oscillation start oscillation condition

    Publication Year: 2004 , Page(s): 2184 - 2188
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    In a practical helix traveling-wave tube (TWT), there is always attenuator/sever for suppressing the oscillations, including backward-wave oscillation (BWO). The factors of the influencing BWO include start position of the attenuator, its length, and attenuation quantity. In the event that the attenuator/sever and nonuniformities in the phase velocity and beam potential were considered, a linear theory is employed to analyze BWO start oscillation condition. Numerical results show that the start oscillation length of the TWT decreases when the start position of the attenuator is close to the input section of the slow wave structure (SWS), that Start oscillation current of the output section of the SWS increases as the attenuation length decreasing, or the attenuation quantity increasing or the nonuniformities becoming strong, and that, however, when the phase velocity or beam potential exceeds a particular value, no oscillation condition could be found. View full abstract»

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  • Experimental observation of image sticking phenomenon in AC plasma display panel

    Publication Year: 2004 , Page(s): 2189 - 2196
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1232 KB) |  | HTML iconHTML  

    The itinerant strong sustain discharge that occurs during a sustain period over a few minutes causes image sticking, which means a ghost image remains in the subsequent image when the previous image was continuously displayed over a few minutes. Accordingly, this paper investigates whether the dominant factor in image sticking is the MgO surface or phosphor layer by testing the effects of image sticking in subsequent dark and bright images using a 42-in plasma display panel. When the subsequent image was dark, the image sticking was found to produce a brighter ghost image than the background. Thus, since the luminance of a dark image is produced by the weak discharge that occurs during the reset-period, the higher luminance of the ghost image was mainly due to the activation of the MgO surface. Conversely, when the subsequent image was bright, the image sticking was found to produce a darker ghost image than the background. Thus, since the luminance of a bright image is predominantly produced by the strong discharge that occurs during the sustain period, the lower luminance of the ghost image was mainly due to the deterioration of the phosphor layer. View full abstract»

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  • Experiments on plasma-physical aspects of closed cycle MHD power generation

    Publication Year: 2004 , Page(s): 2197 - 2209
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2496 KB) |  | HTML iconHTML  

    In this paper, important laboratory experiments in closed-cycle magneto-hydrodynamic (MHD) generator plasmas are discussed. The following aspects are treated: electron temperature elevation and nonequilibrium ionization, fluctuations and nonuniformity, streamers as the nonlinear appearance of ionization instability, inlet relaxation, and fully ionized seed as a concept to suppress ionization instability. Conclusions are presented on electrical transport parameters in nonuniform plasmas, streamer fine structure, streamer velocity, streamer initiation in relation to inlet relaxation, and the fully ionized seed concept. View full abstract»

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  • PIC simulation of effect of energy-dependent foil transparency in an axially-extracted vircator

    Publication Year: 2004 , Page(s): 2210 - 2216
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    We have performed two-dimensional, relativistic, electromagnetic, particle-in-cell simulations for an axially extracted vircator. With a copper foil anode, the output frequency of the vircator is found to be strongly dependent upon the variation of foil transparency with electron energy. Using an average transparency for all electron energies yields results that are markedly different from those obtained using the actual variation. However, the output power shows only mild sensitivity. Using the full energy-dependent form of the transparency, we get fairly good agreement with published experimental results. Increasing the energy resolution for the calculation of foil transparency increases the accuracy of calculation of the dominant frequency, although the frequency tends to saturate beyond a certain resolution. However, an increase in the resolution must necessarily be accompanied by an increase in the number of simulation particles, in order to limit statistical fluctuations to an acceptable level. A physical explanation has also been provided for these trends. View full abstract»

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  • Plasma-sheath transition in the magnetized plasma-wall problem for collisionless ions

    Publication Year: 2004 , Page(s): 2217 - 2226
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB) |  | HTML iconHTML  

    A model for the collisionless plasma-wall problem under the action of an applied magnetic field is developed. The behavior of its solution is examined and found to be qualitatively consistent with experiment. The plasma and the sheath are then modeled separately to obtain the position of the quasi-neutral plasma boundary and the position of the edge of the electron-free sheath. It is shown that the plasma boundary can be specified as the point where the component of the ion velocity normal to the wall reaches the ion sound speed (Bohm criterion), and the sheath edge is specified as the point corresponding to Godyak's condition for the electric field. Studying the behavior near the plasma boundary and the sheath edge, the plasma solution and the solution of the space charge region are patched together to approximate the solution of the plasma-wall problem. View full abstract»

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  • Soft X-ray optimization studies on a dense plasma focus device operated in neon and argon in repetitive mode

    Publication Year: 2004 , Page(s): 2227 - 2235
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    This paper investigates the emission characteristics of a high-performance low-energy (3-kJ) repetitive dense plasma focus device, NX2, operated at up to 1-Hz repetition rate to develop it as an intense source of soft X-rays (SXR) for microlithography and micromachining. Various SXR yield optimization studies with argon and neon as filling gases were performed under different operating conditions (charging voltage, filling pressure, anode length, and insulator sleeve length). The SXR yield was computed using signals obtained from a PIN diode SXR spectrometer with appropriate filters. When operated in neon, the average optimum SXR (λ∼1 nm) yield in 4π steradians was found to be up to 140 J/shot, which corresponded to a wall plug efficiency of 5.6%. Operation in argon showed that optimized SXR (λ∼0.4 nm) yield was up to 1.3 J/shot. While operating with neon under optimized conditions with a water-cooled anode in repetitive mode, the NX2 device was used as a SXR source to imprint a test lithograph on a highly sensitive chemically-amplified resist SU-8. Test structures showing the effect of a stepper with aspect ratio 3:1 on 10-μm-thick SU-8 resist film were obtained. View full abstract»

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  • A novel overmoded slow-wave high-power microwave (HPM) Generator

    Publication Year: 2004 , Page(s): 2236 - 2242
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    We present the design and experimental results of a novel overmoded slow-wave high-power microwave (HPM) generator that is featured by its compactness, low-operation magnetic field, and potentially high power and high efficiency. The device includes two slow-wave structure (SWS) sections, a resonant cavity, and a tapered waveguide. The resonant cavity was well designed and was used to achieve the axial mode selection and to decrease the length of the SWS sections. The radial mode selection is achieved using the property of "surface wave" of the device to excite the TM01 mode while making the higher TM0n modes unexcited. The physical mechanisms of axial and radial mode selections ensure that the microwave is produced with a single mode and a narrow band. The feasibility of low magnetic field operation is also investigated based on the characteristics of the overmoded slow-wave devices. Experiments were carried out at the Spark-2 accelerator. At diode voltage of 474 kV, beam current of 5.2 kA, and guiding magnetic field strength of 0.6 T, a microwave was generated with power of 510 MW, mode of TM01, and frequency of 9.54 GHz. The relative half width of the frequency spectrum is Δf/f= 0.6%, and the beam-to-microwave efficiency is about 21% in our experiment. View full abstract»

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  • Imaging and spectrum diagnostics of air arc plasma characteristics

    Publication Year: 2004 , Page(s): 2243 - 2249
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    This paper is devoted to the study of the air arc plasma characteristics and consists of two parts. An optical high-speed imaging system is integrated with pressure sensing, arc current, and voltage measurement to investigate high-speed and high-temperature unsteady arc plasma motion in a molded case circuit breaker (MCCB) model, especially with the influence of polyoxymethylene (POM), polycarbonate (PBT), nylon, and ceramic arc chamber wall materials. It demonstrates that the performance can be improved effectively by adopting POM and nylon gassing materials. Also, spectrum diagnostics is introduced to analyze the influence of polymethylmethacrylate (PMMA) gassing material on the temperature of arc in a simple model. It shows that material added adjacent to cathode is more effective to cool the arc, compared with the case of anode. View full abstract»

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  • Microwave breakdown in slots

    Publication Year: 2004 , Page(s): 2250 - 2262
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    The properties of microwave-induced breakdown of air in narrow metallic slots are investigated, both theoretically and experimentally, with emphasis on factors important for protection against transmission of incident high-power microwave radiation. The key factors investigated are breakdown power threshold, breakdown time, peak-leakage power, and total transmitted energy, as functions of incident pulse shape and power density. The theoretical investigation includes estimates of the electric field intensification in narrow slots and basic breakdown plasma modeling. New results important for application to the high-power microwave field, such as the influence of pulse shape on breakdown time and peak-leakage power, are presented. The experimental investigation comprises a set of slot breakdown experiments at atmospheric pressure, which are analyzed to extract key parameters, such as transmission cross section, breakdown time, peak leakage power, and transmitted energy. The experimental data is compared and shown to be in good agreement with results obtained in the theoretical investigation. View full abstract»

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  • Intermodulation and noise suppression of a linearized, low-noise hybrid microwave amplifier

    Publication Year: 2004 , Page(s): 2263 - 2264
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    A new type of microwave amplifier module, consisting of a solid-state amplifier, a predistortion linearizer, and a traveling-wave-tube (TWT), is realized. Measurements show a noise figure of 2.2 dB at 9.5 GHz and the third-order intermodulation distortion ratio of 53 dBc at 10 dB back off from P1 dB point. View full abstract»

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  • Comments on "On asymptotic matching and the sheath Edge"

    Publication Year: 2004 , Page(s): 2265 - 2270
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    In Sternberg and Godyak (2003), the authors claim that the sheath edge obtained through asymptotic matching is the edge of the electron free ion sheath characterized by Godyak's "strong" electric field |E|=kTe/(eλD). I present a careful re-analysis of the same problem and show that the paper is incorrect. The "intermediate region" of asymptotic analysis has an extremely narrow validity range in potential space and does not contain the ion-electron sheath. Consequently, in asymptotic theory, the sheath edge is uniquely defined by the transition from the quasi-neutral plasma to the ion-electron sheath. It may equivalently be characterized by the Bohm criterion or by a "medium" electric field |E|∼kTe/(eL35/λD25/) mediating between strong sheath fields |E|∼kTe/(eλD) and weak plasma fields |E|∼kTe/(eL). View full abstract»

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  • Reply to comments on "On asymptotic matching and the sheath Edge"

    Publication Year: 2004 , Page(s): 2271 - 2276
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    In our recent paper [Sternberg and Godyak (2004)], we have solved the plasma-sheath problem using asymptotic matching techniques. We have shown that the position of the sheath edge obtained by asymptotic matching yields the position of the ion sheath edge determined by Godyak's condition (E=kTe/(eλD1)) [Godyak (1982)]. In addition, we were able to show how the sheath width depends on the voltage applied to the wall. Our results are theoretical, grounded in mathematics. We used numerical computations mainly to illustrate our point. We have written our paper with great care, so that any scientist, even one not familiar with the intricacies of asymptotic matching, could understand our exposition and be convinced in the correctness of our results. Kaganovich (2004) reproduced our theoretical results numerically up to ε=10-11. Franklin (2004) published a review adapting our results and interpretations. However, we were not able to convince Riemann, although he reproduced some of our results numerically [Riemann (2004)]. This paper is a response to Riemann's comments [Riemann (2004)]. View full abstract»

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  • Special issue on vacuum discharge plasmas

    Publication Year: 2004 , Page(s): 2277
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  • Special issue on plasma-assisted combustion

    Publication Year: 2004 , Page(s): 2278
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  • 2004 Index

    Publication Year: 2004 , Page(s): 2279 - 2318
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  • Explore IEL IEEE's most comprehensive resource [advertisement]

    Publication Year: 2004 , Page(s): 2319
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  • Proceedings of the IEEE celebrating 92 years of in-depth coverage on emerging technologies

    Publication Year: 2004 , Page(s): 2320
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    Freely Available from IEEE
  • IEEE Transactions on Plasma Science Information for authors

    Publication Year: 2004 , 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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