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Plasma Science, IEEE Transactions on

Issue 6 • Date Dec. 2001

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Displaying Results 1 - 19 of 19
  • Author index

    Publication Year: 2001 , Page(s): 977 - 982
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  • Subject index

    Publication Year: 2001 , Page(s): 982 - 996
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  • Clean-up by gas-particle transformation under the action of a corona discharge: application to volatile iodine compounds

    Publication Year: 2001 , Page(s): 881 - 887
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (126 KB) |  | HTML iconHTML  

    The ionization of gas induced by the establishing of a corona discharge causes gas-particle transformation of the iodomethane. A radioactive tracer (iodine 131) is used to produce elementary iodine balances for the overall process. The experimental results show the benefit of this procedure for the purification of radioactive gaseous iodine compounds. There is a transfer of activity from the gaseous phase to the solid phase. Transformation levels can reach 80% under our experimental conditions. The experimental study of aerosols produced downstream of the corona discharge evidences the need to carry out this process in three successive stages View full abstract»

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  • Relativistic motion of a charged particle driven by an elliptically polarized electromagnetic wave propagating along a static magnetic field

    Publication Year: 2001 , Page(s): 903 - 906
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB) |  | HTML iconHTML  

    The relativistic equations of motion of the interaction of a charged particle with an electromagnetic wave of elliptic polarization propagating along the direction of an external and constant magnetic field are solved in exact form. The method of solution is straight forward and allows to recover results previously reported in the literature View full abstract»

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  • A microwave generated plasma in a tunable resonant cavity for studies of turbulence in weakly ionized gases

    Publication Year: 2001 , Page(s): 965 - 969
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (100 KB) |  | HTML iconHTML  

    A microwave plasma in argon is generated inside a pyrex tube by a 3-kW power supply in combination with a magnetron, wave guide, and a resonant cavity. The gas pressure is varied from 200 to 2000 mtorr, and the microwave output power is varied from 600 to 1200 W. Plasma parameters are determined by using a single Langmuir probe. Bias voltage and current characteristic curves are analyzed for the determination of electron temperature, density, and plasma potential. Electron density is found to be in the range of 1.4-7.6 × 1011 cm-3 , electron temperature 4.2-6.2 eV, and plasma potential 22.6-35.6 volts. Turbulence in plasma emissions can now be studied in these various regimes using Ar I lines View full abstract»

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  • A simple knife-edge design for initial phase optimization in plasma focus

    Publication Year: 2001 , Page(s): 973 - 976
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (130 KB) |  | HTML iconHTML  

    A simple knife-edge design was described that enabled easy optimization and investigation of the initial phase for the plasma focus devices. It enhanced the initial breakdown process along the insulator surface by allowing free adjustment or fine-tuning of the insulator length and by forming a sharp knife-edge with effective field emission. The plasma pinching was much improved with neutron yield equal or above that predicted by the scaling law. This knife-edge design is especially suitable for the optimization of medium and large-scale plasma focus devices where it would be otherwise rather difficult to modify the insulator configuration directly View full abstract»

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  • An experimental study of the dependence on the current intensity of the erosion of thoriated tungsten cathodes in plasma arcs

    Publication Year: 2001 , Page(s): 888 - 894
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (181 KB) |  | HTML iconHTML  

    The erosion occurring in thoriated tungsten cathodes used in transferred plasma torches operating with current intensities ranging from 30 to 210 A has been experimentally investigated. The cathode erosion rate was determined by measuring the cathode's weight loss after arcing, and the eroded cathode surface was explored by a scanning electron microscope and an energy dispersive X-ray spectrometer. It has been discovered that a critical current intensity, ICR ~ 50 A, exists for which the cathode erosion rate becomes maximum View full abstract»

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  • Absolute spectral distribution of soft X-ray emission from laser produced gold plasma

    Publication Year: 2001 , Page(s): 960 - 964
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (94 KB) |  | HTML iconHTML  

    Quantitative measurement of spectral distribution of soft X-ray emission from laser produced plasmas and estimation of X-ray conversion efficiency are reported. The X-ray emission from planar gold target irradiated by an Nd:glass laser was recorded using a high resolution transmission grating spectrograph. Spectral distribution of X-ray intensity was derived using calibrated film data and a deconvolution procedure to account for contribution of higher diffraction orders. Results of conversion efficiency per unit solid angle, at a laser intensity of ~4×1012 W/cm2L = 1.054 μm), for 10< λ <80 Å and in the water window spectral region (23< λ< 44 Å) are presented. A three-fold increase in conversion efficiency was observed for second harmonic laser irradiation (λL = 0.527 μm) at an intensity of 8×1012 W/cm2 View full abstract»

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  • Experimental investigation of a 140-GHz coaxial gyrotron oscillator

    Publication Year: 2001 , Page(s): 943 - 950
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB)  

    We report experimental results on a megawatt power level, 140-GHz coaxial gyrotron oscillator. The gyrotron has an inverted magnetron injection gun (IMIG) designed for operation at up to 95 kV and 88 A. The IMIG has an inner grounded anode which extends from the center of the gun down through the entire length of the tube including the cavity and collector. The IMIG was tested at up to 105 kV and 93 A in 3 μs pulses, achieving an electron beam power of 10 MW. The output power from the coaxial gyrotron cavity was transported to an internal mode converter and a single mirror that coupled the power out transversely from the tube axis. A maximum output power of up to 1 MW was obtained in the TE27,11 mode at 142 GHz at an efficiency of 16%, about one half of the design efficiency. The reduced efficiency was attributed to nonuniformity of the cathode emission and the sensitivity to the relative alignment of the electron gun, coaxial insert, and cavity. The cathode emission over the azimuthal angle was measured for two cathodes and was shown to be nonuniform due to both temperature and emitter work function nonuniformity. The gyrotron was also tested in two alternate configurations: 1) with the internal mode converter removed (axial output), and 2) with both the internal converter and the coaxial insert removed (empty cavity). In operation in the empty cavity configuration, which is equivalent to a conventional gyrotron oscillator, output power of up to 0.9 MW was observed View full abstract»

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  • Non-Maxwellian shape of electron distribution function in ion acoustic turbulence

    Publication Year: 2001 , Page(s): 907 - 910
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    In a DC discharge plasma system, in which two meshes are installed, the current-driven ion acoustic instability is excited when a de potential Vm is applied to one of them. When the instability fully grows, the system reaches a very turbulence state, the so-called ion acoustic turbulence. The experimental measurement of energy distribution function of electrons in ion acoustic turbulence measured by the Langmuir probe shows a non-Maxwellian nature along with electron heating View full abstract»

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  • The influence of dielectric surface charge distribution upon the partial discharge behavior in short air gaps

    Publication Year: 2001 , Page(s): 866 - 874
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (197 KB)  

    A two-dimensional breakdown model based upon the continuity equations for electrons and ions and the Poisson equation is employed to examine the influence of surface charges upon the partial discharge behavior of a short metallic-dielectric plane-parallel electrode gap of 0.05 cm in an air-like mixture at atmospheric pressure. The form of charge distribution at the dielectric electrode surface is found to significantly affect a number of important discharge parameters, such as the uniformity of the electric field, the charge density and its radial distribution within the gap, as well as the discharge propagation time View full abstract»

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  • A time-domain circuit simulator for coupled-cavity traveling-wave tubes

    Publication Year: 2001 , Page(s): 911 - 920
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    The Curnow equivalent circuit was used to predict the dispersion of cold coupled-cavity traveling-wave tubes, as wen as the voltage and current characteristics for lossless and lossy multicavity circuits. The equivalent circuit is extended to have three ports. The added beam port allows the future modeling of the interaction between beam and cavity. Losses are introduced into the circuit as resistors in series with the corresponding inductors. The time-domain solution to the multicavity circuit is developed. It can be applied to the full-spectrum signal. It is also useful for the transient analysis for both single frequency and full-spectrum signals, including the turn-on transients. Numerical methods to solve the time-domain equations are discussed; a second-order leap-frog method and a fourth-order Runge-Kutta method are implemented and analyzed. Simulation results from both codes are compared, and match well with the theory View full abstract»

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  • Behavior of the photoelectron boundary layer with sinusoidal time dependence

    Publication Year: 2001 , Page(s): 935 - 942
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB) |  | HTML iconHTML  

    At high-incident photon intensities (X-rays, UV, or visible), a photoelectron boundary layer can form. This layer's properties, and especially its electric dipole moment, change in a nonlinear way as the light intensity varies in time. We show here that the dipole moment obeys an exact dynamical equation, which can be used as the basis for analytic approximation schemes for a driver of arbitrary time dependence. An approximate analytic solution for a sinusoidally oscillating light source is presented, and compared with a particle-pusher numerical simulation. Scaling laws are extracted from the analytic solution View full abstract»

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  • Characteristics of a high-power RF oscillator based on a pulsed hollow-cathode discharge

    Publication Year: 2001 , Page(s): 895 - 902
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (229 KB)  

    The characteristics of a very simple high-power pulsed RF oscillator are presented. This oscillator is based on the use of a low-pressure pulsed hollow-cathode discharge during the periods when its cathode sheath becomes unstable. A set of four different oscillators has been studied in different operating regimes for various values of load resistance. These oscillators were tested and found to produce pulsed power of over 100 kW with efficiency exceeding 20% at frequencies up to 50 MHz. The tests were performed with pulse duration of 14 μs and repetition rate up to 100 Hz. Equivalent circuits of the oscillator for RF loading and for DC current are described. The requirements for a power supply to drive the device as well as recommendations for the oscillator usage are presented View full abstract»

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  • Analytical calculations and comparison with numerical data for annular klystrode

    Publication Year: 2001 , Page(s): 875 - 880
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB) |  | HTML iconHTML  

    The performance of a klystrode is investigated for annular electron beams. Numerical simulations of the output cavity in the klystrode device are carried out by making use of the fully electromagnetic three-dimensional code, HFSS, and the fully electromagnetic, two-and-one-half-dimensional, self-consistent PIC code, MAGIC. In addition, an analytical expression to predict the efficiency and gap-field strength of the device is developed to investigate klystrode performance over a wide range of parameters. This analytical expression for the annular klystrode is developed based on the Maxwell's equations and Newton's second law of motion. The analytical results agree fairly well with data obtained numerically from the MAGIC code. The presented results indicate that the theoretical formula obtained from the analytical calculation may be useful for designing the klystrode microwave tubes View full abstract»

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  • Scaling characteristics of plasma parameters for low-pressure oxygen RF discharge plasmas

    Publication Year: 2001 , Page(s): 970 - 973
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (97 KB) |  | HTML iconHTML  

    For a low-pressure (1-100 mtorr) oxygen RF discharge plasma, the scaling laws for the densities of charged species such as positive ion, negative ion, and electron are estimated in terms of external and internal plasma parameters for the ion-flux-loss-dominated region based on the global balance equations. The scaling formulas are compared with Langmuir probe measurement results performed on a planar inductively coupled oxygen plasma. The transition point from the ion-flux-loss-dominated region to the recombination-loss-dominated region moves to a lower pressure region as the absorbed power increases View full abstract»

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  • Temporal evolution of electron beam transport in PASOTRON microwave sources

    Publication Year: 2001 , Page(s): 951 - 959
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    The plasma-assisted slow-wave oscillator (PASOTRON) is a high-power microwave source, in which the transport of an intense electron beam through an interaction region is based on the focusing effect of a beam generated plasma channel (Bennett pinch). A simple theory is developed which describes the self-consistent nonstationary processes of the plasma formation due to impact ionization of an axially inhomogeneous gas by the beam and the beam focusing effect of the plasma. The theory is illustrated by examples showing the temporal evolution of the beam transport in the process of plasma creation in PASOTRONs View full abstract»

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  • A cold thermionically emitting dusty air plasma formed by radiative heating of graphite particulates

    Publication Year: 2001 , Page(s): 927 - 934
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    Formation of an atmospheric pressure dusty air plasma is explored experimentally in this paper. The plasma is created by seeding an air flow with graphite particles and irradiating the particulates with a focused CO2 laser beam. The graphite particles are, thus, heated to thermionically emitting temperatures, and average particle temperatures and average particle number densities are measured. The presence of charges is inferred both from these measured quantities using a simple theoretical transient model, and experimentally by applying a dc bias across the irradiated region. It is found that an electron density of ~6.7 × 105 cm-3 (6.7 × 1011 m-3) can be produced at steady state in the presence of O2. This value can be increased to 3.6 × 107 cm-3 (3.6 × 1013 m -1) in the ideal case where an electron attachment to O2 is suppressed and where a lower work function particulate is used View full abstract»

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  • Small plasma focus studied as a source of hard X-ray

    Publication Year: 2001 , Page(s): 921 - 926
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    An experimental study on hard X-ray pulses emitted by a small plasma focus is performed, regarding its application to biological radiographs in fast dynamic situations. It is found that the radiation intensity in a single shot is high enough to obtain fine resolution radiographs in very short exposures (about 10 ns). As an example, a radiograph on a live mouse is shown. It is found that the relation between responses of different detectors, i.e., thermoluminescence dosimeters and scintillator-photomultiplier, is linear View full abstract»

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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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