Scheduled System Maintenance:
Some services will be unavailable Sunday, March 29th through Monday, March 30th. We apologize for the inconvenience.
By Topic

Plasma Science, IEEE Transactions on

Issue 2 • Date Apr 1998

Filter Results

Displaying Results 1 - 13 of 13
  • Decay instability in a plasma channel

    Publication Year: 1998 , Page(s): 141 - 144
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    Near the critical layer, a large-amplitude laser beam creates a transverse plasma channel due to the ponderomotive force. The axis of the channel is normal to the ambient density gradient. Inside the channel, the laser beam decays into counter-propagating ion acoustic and Langmuir waves. A nonlocal theory of the process is developed for a parabolic density profile. The growth rate of the instability is significantly reduced due to the nonlocal effects View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonlinear interaction of microwave and plane magnetoactive plasma layer

    Publication Year: 1998 , Page(s): 150 - 158
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    A method for calculating the interaction of a microwave with a plane layer of magnetoactive low-pressure plasma is presented. In this paper, the plasma layer is situated between a plane dielectric layer and a plane metal screen. The calculation model contains the microwave energy balance, particle balance, and electron energy balance. The numerical calculations of the nonlinear interaction of the incident plane microwave and the plane plasma layer show that there are hysteresis phenomena when the intensity of the incident microwave is changed. The cause of these hysteresis phenomena is considered. As a result of this investigation, the conditions of effective power transfer from the microwave to the plasma have been found View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electrical characteristics of helicon wave plasmas

    Publication Year: 1998 , Page(s): 159 - 166
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The external electrical characteristics of helicon wave plasmas have been studied over a wide range of magnetic fields, radio frequency (RF) power, frequencies, and Ar gas pressures. External parameters, such as antenna voltage, current, and phase shifts, and internal parameters, such as electron density, are measured. The equivalent discharge resistance, reactance, and power transfer efficiency are calculated through these measurements. The characteristics of helicon mode is compared with inductively coupled plasma (ICP) and low mode. The power efficiency of the helicon mode is better than that of other modes. Consequently, electron density of helicon mode is much higher than that of other modes. This means the existence of a mechanism where electrons are very efficiently accelerated by the electric field of the antenna in the helicon mode. The power efficiency of helicon mode is higher at lower RF frequency and at optimum gas pressure than that of other modes View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of nonlocal electron kinetics and transition from α to γ regime in an RF capacitive discharge in nitrogen

    Publication Year: 1998 , Page(s): 167 - 174
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    The electron kinetics and regime of operation of asymmetrically coupled RF (27-MHz) nitrogen discharges in two vessels with different interelectrode gaps over the range of 0.20-0.35 torr gas pressure are studied in terms of the electron energy distribution function (EEDF). The latter is measured by means of a computer-controlled data acquisition system, a Langmuir probe with cross-modulation second derivative technique applied. The experiments are performed with an axial resolution along the RF electric field and accompanied with a measurement of electrical discharge characteristics. The effects of local and nonlocal plasma response are considered. The transition between α and γ discharge regimes is registered by measuring the EEDF and its moments' changes with the increase of the RF discharge current density View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of the pulse repetition rate on the composition and ion charge-state distribution of pulsed vacuum arcs

    Publication Year: 1998 , Page(s): 220 - 226
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    The plasma composition and ion charge-state distributions of pulsed vacuum arcs have been investigated for carbon, aluminum, silver, platinum, and tantalum cathodes using a time-of-flight (TOF) charge-to-mass spectrometer. With the exception of carbon, it was found that all results depend on the arc pulse repetition rate, a fact which, up to now, has not been reported in the literature. It is shown that adsorption of gas on the cathode between are pulses leads to contamination of the metal plasma and to a reduction of metal ion charge states. These usually undesired effects can be avoided by operating at high arc pulse repetition rates of order 10 Hz or more. The results can be interpreted in terms of cathode spot type 1 (on contaminated cathode surfaces) and type 2 (on clean surfaces) which are well known from their different brightness and erosion behaviour. The transition between these modes was found to be gradual View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonlocal ion transport in a weakly ionized nonequilibrium plasma

    Publication Year: 1998 , Page(s): 198 - 207
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Nonlocal ion transport in a weakly ionized plasma with a strong electric field is analyzed. It is assumed that charge-exchange interactions are the main mechanism of ion scattering. Ion density and drift velocity are determined for nonuniform time varying electric field by using both the direct solution of the kinetic equation and the Chapman-Enskog-type approach. The ion mean velocity is given by an integro-differential operator applied to the electric field. Ion density and drift velocity exhibit resonant behaviour when ω≃kW0, which corresponds to the resonance between ions moving with average velocity W0 and wave traveling with the phase velocity ω/k View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Experimental investigation of large-volume PIA plasmas at atmospheric pressure

    Publication Year: 1998 , Page(s): 145 - 149
    Cited by:  Papers (6)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    Large-volume atmospheric-pressure plasmas have been the subject of previous research as a laboratory simulation of ball lightning, but measurements of the plasma properties have been unavailable. The present investigation employed a non-resonant microwave chamber with a 1000-W microwave-source operating at 2.45-GHz frequency to produce large volume (up to 0.8 L) plasmas that persisted after microwave shutoff. A Langmuir probe was used to measure electron density and temperature, and the highest values measured were 1010 cm-3 at 0.67 eV, respectively. Plasma lifetimes after microwave shutoff were also measured, using both a photocell and a video camera, and were found to average 200 ms. A working hypothesis of the formation of shared electron orbitals in dense gas discharges is put forth to explain this phenomenon View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling the pressure dependence of DC bias voltage in asymmetric, capacitive RF sheaths

    Publication Year: 1998 , Page(s): 181 - 189
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    A semianalytical model for capacitively coupled radio frequency (RF) sheaths of asymmetric (unequal electrode area) systems has been developed. It can be applied in the high-frequency (ω > ω pi) regime at different pressures. An analytical approximation to the pressure-dependent ion density profile is used. The time-varying electric field and potential within the sheath are obtained by solving Poisson's equation. The current balance and zero net DC current conditions are applied to solve for the RF sheath parameters and DC bias voltage. The DC voltage ratio between the powered and grounded electrode sheaths increases as the pressure decreases, which results in a larger DC bias voltage at lower pressures View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A theoretical formula of E-H discharge transition power in a transformer-coupled discharge

    Publication Year: 1998 , Page(s): 190 - 197
    Cited by:  Papers (15)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Based on the recently developed heating theory (see Yoon et al., Phys. Rev. E, vol.55, no.6, p.7536-48 (1997)), a theoretical formula of E- and H-discharge transition power in a transformer-coupled plasma (TCP) discharge has been developed. The present result agrees well with an experimental observation for argon discharge View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Particle simulation of radio-frequency plasma discharges of methane for carbon film deposition

    Publication Year: 1998 , Page(s): 125 - 134
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Particle-in-cell/Monte Carlo (PIC/MC) simulations of capacitively coupled radio-frequency (RF) glow discharges were carried out for low pressure CH4 plasmas. The present computational scheme includes the motions and collisions of both neutral and charged particles. The CH4 plasma is modeled by combining a one-dimensional PIC/MC method with a polyatomic particle collision scheme. The model considers the motions of CH4, CH4+, CH3, C2H5, H2, H, and electrons. Space and time dependent results show ionization rate is high at the sheath region. The dissociation rate of CH4 is found to be high at the sheath as well as in the plasma bulk. Deposition rate of carbon film is calculated by sampling impinging particles at at the powered electrode. The calculations show that neutral radicals are the major depositing species for the cases studied. Ion energy impinging to the electrode was found to be strongly dependent on the “imposed” dc bias (as opposed to self-bias) voltage for a given RF voltage. Deposition rate was found to be almost independent of the “imposed” dc bias voltage as the RF voltage remained constant View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma-immersion ion implantation of the interior surface of a small cylindrical bore using an auxiliary electrode for finite rise-time voltage pulses

    Publication Year: 1998 , Page(s): 175 - 180
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    Plasma-immersion ion implantation (PIII) can be used to process the interior surfaces of odd-shape specimens such as a cylindrical bore. The temporal evolution of the plasma sheath in a small cylindrical bore in the presence of a grounded coaxial auxiliary electrode is derived for voltage pulses of different rise times by solving Poisson's equation and the equations of ion continuity, and motion numerically using the appropriate boundary conditions. It is found that the maximum ion impact energy and the average impact energy are improved for finite rise-time voltage pulses, and shorter rise times yield better results. Our results allow the selection of a suitable auxiliary electrode radius to improve the average impact energy for a given rise time View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Soft X-ray yield measurement in a small plasma focus operated in neon

    Publication Year: 1998 , Page(s): 135 - 140
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    The United Nations University/International Center for Theoretical Physics Plasma Focus Facility (UNU/ICTP PFF), a small plasma focus, has proven very useful as a training device for research initiation and as a test bed for applications. In this work, its performance in terms of a soft X-ray (SXR) source is examined. The total SXR yield when operated in neon is measured using low-cost detectors, including a calorimeter and a five-channel filtered PIN system. For a charging voltage of 14 kV with 2.9 kJ stored energy, the optimum operating pressure in neon is found to be in the range of 2.7-3.3 torr, resulting in a total SXR yield of 6J/shot into 4π steradians measured by the calorimeter in agreement with the PIN detectors. Spectral data shows that 64% of the total SXR yield is contributed by the Ly-α and He-α lines and 36% by the rest, mainly the radiative recombination. The low total SXR yield (0.2 % of stored energy) is consistent with numerical computations of focus dynamics, which reveals that 3% of stored energy is converted into plasma energy. This low conversion rate into plasma energy is due to the large inductance of 110 nH of this simple single-capacitor device. Thus, for development as a SXR source, reduction of inductance is necessary View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Energetic electron and ion beam generation in plasma opening switches

    Publication Year: 1998 , Page(s): 208 - 219
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    In this paper, we present measurements of ion and electron flows in a nanosecond plasma opening switch (NPOS) and a microsecond plasma opening switch (MPOS), performed using charge collectors. In both experiments, an electron flow toward the anode, followed by an ion flow, were observed to propagate downstream toward the load side of the plasma during the plasma opening switch (POS) conduction. In the MPOS, ion acceleration was observed to propagate axially through the entire plasma. These results are in satisfactory agreement with the predictions of the electron magnetohydrodynamics (EHMD) theory and the results of fluid and particle-in-cell (PIC) code simulations. At the beginning of the POS opening, a high-current density (≈2 kA/cm2) short-duration (10-30 ns) axial ion flow downstream toward the load was observed in both experiments, with an electron beam in front of it. These ions are accelerated at the load side of the plasma and are accompanied by comoving electrons. In the NPOS, the ion energy reaches 1.35 MeV, whereas in the MPOS, the ion energy does not exceed 100 keV. We suggest that in the NPOS the dominant mechanism for the axial ion acceleration is collective acceleration by the space charge of the electron beam, while in the MPOS, axial ion acceleration is probably governed by the Hall field in the current carrying plasma View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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.

 

 

Full Aims & Scope

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
tps-editor@ieee.org
Phone:505-988-5751
Fax:505-988-5751 (call first)