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May 2001

Volume 8, Issue 5, pp. 1447-2594

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back to top Low-temperature Plasmas, Plasma Applications, Plasma Sources, Sheaths

Thermohydrodynamic characteristics of the cascaded arc plasma generator with a large ratio of radius and pipe length

K. Shimada, M. Iwabuchi, and N. Matsuda

Phys. Plasmas 8, 1722 (2001); http://dx.doi.org/10.1063/1.1349872 (7 pages)

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Numerical analysis was performed on the laminar thermal plasma flow of a constricted cascaded arc plasma generator with a larger ratio of radius and pipe length compared to previously used arc plasma generators. The numerical results concerning plasma temperature and velocity were compared with the experimental data measured using the probes methods. The effects of the mass flow rate of the plasma gas and the supplied current on plasma temperature, velocity, and current at a cross section of the plasma torch are clarified. These effects on plasma temperature and current density are estimated to be small when using a numerical model employing a single flow and a single temperature without taking into account the effects of the collision and dispersion of plasma gas particles. Except for the large mass flow rate of plasma gas, the numerical results for the plasma velocity are almost identical in magnitude to the experimental data. © 2001 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.50.Dg Plasma sources
52.25.Kn Thermodynamics of plasmas
52.25.Fi Transport properties

Laser induced fluorescence of argon ions in a plasma presheath

L. Oksuz, M. Atta Khedr, and N. Hershkowitz

Phys. Plasmas 8, 1729 (2001); http://dx.doi.org/10.1063/1.1358312 (5 pages) | Cited 41 times

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The characteristics of presheaths near an electrically floating plate in weakly collisional argon multidipole plasmas are investigated with a combination of data from laser induced fluorescence using a diode laser, Mach probes, emissive probes, and Langmuir probes. It is shown that ion–neutral collisions result in an increase in ion temperature from approximately room temperature in the bulk plasma to 0.13 eV, 0.5 cm from the plate, the location of the closest measurement. In addition, at that point, the presheath plasma potential drop is greater than Te/2, and the drift velocity is equal to 0.5 cs, where cs is the ion sound velocity. © 2001 American Institute of Physics.
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52.40.Kh Plasma sheaths
52.70.Ds Electric and magnetic measurements
52.25.Kn Thermodynamics of plasmas

High-energy plasma acceleration by means of an ideal arcjet thruster

Kei-ichi Hirano

Phys. Plasmas 8, 1734 (2001); http://dx.doi.org/10.1063/1.1355675 (12 pages)

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A theoretical study is presented on the entropy acceleration of a plasma by means of an ideal arcjet thruster made up of two major parts; an arc column of a uniform temperature between the cathode and the anode, and the heating zone of the injected cold gas. The plasma flow through the arc column follows the Navier–Stokes, since its dynamic viscosity is quite high. Proper boundary values on the cathode surface give a solution that yields sharp plasma acceleration to a high energy by the viscous force. In the heating zone, the flow is driven up mainly by a large temperature difference between the arc and the injected cold gas. The viscous force plasma driving model is applied to the solar wind; good agreement is confirmed between the theory and the observed data. © 2001 American Institute of Physics.
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52.75.Di Ion and plasma propulsion
52.75.Hn Plasma torches

Initial experiments in the Idaho Dusty Plasma Device

Rex Gandy, Shawn Willis, and Hiro Shimoyama

Phys. Plasmas 8, 1746 (2001); http://dx.doi.org/10.1063/1.1365407 (5 pages) | Cited 2 times

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The Idaho Dusty Plasma Laboratory has recently begun operation. Work to date has used an argon dc glow plasma in which dust particles are levitated. Langmuir probe measurements indicate plasma densities in the range 1014–1015 m−3 and electron temperatures in the range 1–5 eV depending on plasma conditions and spatial location. To date monodispersive particles with a diameter range of 20–30 μm have been used. The observed dust clouds have dust densities in the range 1010–1012 m−3. Dust particle average kinetic energies are typically near the electron temperature in magnitude. The bulk of the dust cloud is in a crystalline solid configuration. The motion of the dust can best be characterized as collective normal mode activity. Spectra of the particle motion reveal the distinction between collective and random motion. The dust charge has been measured to be on order of −104e. The variations of particle energy and charge within the dust cloud have been measured. © 2001 American Institute of Physics.
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52.27.Lw Dusty or complex plasmas; plasma crystals
52.25.Vy Impurities in plasmas
52.80.Hc Glow; corona
52.70.Ds Electric and magnetic measurements
52.25.Fi Transport properties
52.35.Py Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.75.-d Plasma devices
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Triggering and guiding high-voltage large-scale leader discharges with sub-joule ultrashort laser pulses

H. Pépin, D. Comtois, F. Vidal, C. Y. Chien, A. Desparois, T. W. Johnston, J. C. Kieffer, B. La Fontaine, F. Martin, F. A. M. Rizk, C. Potvin, P. Couture, H. P. Mercure, A. Bondiou-Clergerie, P. Lalande, et al.

Phys. Plasmas 8, 2532 (2001); http://dx.doi.org/10.1063/1.1342230 (8 pages) | Cited 51 times

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The triggering and guiding of leader discharges using a plasma channel created by a sub-joule ultrashort laser pulse have been studied in a megavolt large-scale electrode configuration (3–7 m rod-plane air gap). By focusing the laser close to the positive rod electrode it has been possible, with a 400 mJ pulse, to trigger and guide leaders over distances of 3 m, to lower the leader inception voltage by 50%, and to increase the leader velocity by a factor of 10. The dynamics of the breakdown discharges with and without the laser pulse have been analyzed by means of a streak camera and of electric field and current probes. Numerical simulations have successfully reproduced many of the experimental results obtained with and without the presence of the laser plasma channel. © 2001 American Institute of Physics.
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52.38.-r Laser-plasma interactions
52.80.-s Electric discharges

Negative ion density fronts

Igor Kaganovich

Phys. Plasmas 8, 2540 (2001); http://dx.doi.org/10.1063/1.1343088 (9 pages) | Cited 13 times

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Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te≫Ti). The boundary separating a plasma containing negative ions, and a plasma without negative ions, is usually thin so that the negative ion density falls rapidly to zero—forming a negative ion density front. Theoretical, experimental, and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow) are reviewed. During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in the analysis of plasma density profile evolution in strongly nonisothermal plasmas. © 2001 American Institute of Physics.
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52.35.Tc Shock waves and discontinuities
52.77.Bn Etching and cleaning

Low-frequency, high-density, inductively coupled plasma sources: Operation and applications

S. Xu, K. N. Ostrikov, Y. Li, E. L. Tsakadze, and I. R. Jones

Phys. Plasmas 8, 2549 (2001); http://dx.doi.org/10.1063/1.1343887 (9 pages) | Cited 95 times

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Operation regimes, plasma parameters, and applications of the low-frequency ( ∼ 500 kHz) inductively coupled plasma (ICP) sources with a planar external coil are investigated. It is shown that highly uniform, high-density (ne ∼ 9×1012 cm−3) plasmas can be produced in low-pressure argon discharges with moderate rf powers. The low-frequency ICP sources operate in either electrostatic (E) or electromagnetic (H) regimes in a wide pressure range without any Faraday shield or an external multipolar magnetic confinement, and exhibit high power transfer efficiency, and low circuit loss. In the H mode, the ICP features high level of uniformity over large processing areas and volumes, low electron temperatures, and plasma potentials. The low-density, highly uniform over the cross-section, plasmas with high electron temperatures and plasma and sheath potentials are characteristic to the electrostatic regime. Both operation regimes offer great potential for various plasma processing applications. As examples, the efficiency of the low-frequency ICP for steel nitriding and plasma-enhanced chemical vapor deposition of hydrogenated diamond-like carbon (DLC) films, is demonstrated. It appears possible to achieve very high nitriding rates and dramatically increase micro-hardness and wear resistance of the AISI 304 stainless steel. It is also shown that the deposition rates and mechanical properties of the DLC films can be efficiently controlled by selecting the discharge operating regime. © 2001 American Institute of Physics.
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52.50.Dg Plasma sources
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.25.-b Plasma properties
52.40.Kh Plasma sheaths

Beam-generated plasmas for processing applications

R. A. Meger, D. D. Blackwell, R. F. Fernsler, M. Lampe, D. Leonhardt, W. M. Manheimer, D. P. Murphy, and S. G. Walton

Phys. Plasmas 8, 2558 (2001); http://dx.doi.org/10.1063/1.1345506 (7 pages) | Cited 10 times

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The use of moderate energy electron beams (e-beams) to generate plasma can provide greater control and larger area than existing techniques for processing applications. Kilovolt energy electrons have the ability to efficiently ionize low pressure neutral gas nearly independent of composition. This results in a low-temperature, high-density plasma of nearly controllable composition generated in the beam channel. By confining the electron beam magnetically the plasma generation region can be designated independent of surrounding structures. Particle fluxes to surfaces can then be controlled by the beam and gas parameters, system geometry, and the externally applied rf bias. The Large Area Plasma Processing System (LAPPS) utilizes a 1–5 kV, 2–10 mA/cm2 sheet beam of electrons to generate a 1011–1012 cm−3 density, 1 eV electron temperature plasma. Plasma sheets of up to 60×60 cm2 area have been generated in a variety of molecular and atomic gases using both pulsed and cw e-beam sources. The theoretical basis for the plasma production and decay is presented along with experiments measuring the plasma density, temperature, and potential. Particle fluxes to nearby surfaces are measured along with the effects of radio frequency biasing. The LAPPS source is found to generate large-area plasmas suitable for materials processing. © 2001 American Institute of Physics.
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52.50.Dg Plasma sources
52.40.Mj Particle beam interactions in plasmas
52.77.-j Plasma applications
52.25.Kn Thermodynamics of plasmas

Modeling of the physics and chemistry of thermal plasma waste destruction

A. B. Murphy and T. McAllister

Phys. Plasmas 8, 2565 (2001); http://dx.doi.org/10.1063/1.1345884 (7 pages) | Cited 9 times

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The application of thermochemical modeling, chemical kinetic modeling, and computational fluid dynamic modeling to waste destruction by thermal plasmas is considered. Destruction of liquid and gaseous wastes in the PLASCON™ waste destruction process is used as an example. It is demonstrated that thermochemical calculation of the mixing temperature is a useful tool to predict the level to which wastes are destroyed; however, chemical kinetic calculations are necessary to investigate the formation of byproducts in the process. Computational fluid dynamic modeling is required to obtain temperature and flow fields in two dimensions. When combined with chemical kinetics, composition fields can also be obtained. These points are illustrated using the examples of chlorobenzene and chlorofluorocarbon destruction. © 2001 American Institute of Physics.
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52.77.-j Plasma applications
82.60.-s Chemical thermodynamics
82.20.-w Chemical kinetics and dynamics
47.11.-j Computational methods in fluid dynamics
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.25.Kn Thermodynamics of plasmas

Transient electrical discharges in small devices

Leopoldo Soto, Andrey Esaulov, José Moreno, Patricio Silva, Gustavo Sylvester, Marcelo Zambra, Andrey Nazarenko, and Alejandro Clausse

Phys. Plasmas 8, 2572 (2001); http://dx.doi.org/10.1063/1.1351829 (7 pages) | Cited 19 times

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Fundamental and applied research on plasmas with high energy density that are unstable and radiate can be done at a relatively low cost with small plasma pinches. In this paper we discuss three experiments using small pinch devices: a capillary discharge, a Z-pinch driven by a small generator, and a low energy plasma focus. The experiments were complemented by magnetohydrodynamics numerical calculations in order to assist the design and physical interpretation of the experimental data. The diagnostics used in the experiments include current and voltage monitors, multipinhole camera, holographic interferometry, and vacuum ultraviolet spectroscopy. © 2001 American Institute of Physics.
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52.58.Lq Z-pinches, plasma focus, and other pinch devices
52.80.-s Electric discharges
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.65.Kj Magnetohydrodynamic and fluid equation
42.40.Kw Holographic interferometry; other holographic techniques
42.40.My Applications

Parametric investigations of a nonconventional Hall thruster

Y. Raitses and N. J. Fisch

Phys. Plasmas 8, 2579 (2001); http://dx.doi.org/10.1063/1.1355318 (8 pages) | Cited 36 times

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Hall thrusters might better scale to low power with nonconventional geometry. A 9 cm cylindrical, ceramic-channel, Hall thruster with a cusp-type magnetic field distribution has been investigated. It exhibits discharge characteristics similar to conventional coaxial Hall thrusters, but does not expose as much channel surface. Significantly, its operation is not accompanied by large amplitude discharge low frequency oscillations. © 2001 American Institute of Physics.
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52.75.Di Ion and plasma propulsion

Pulse electrical discharges in water and their applications

Pavel Šunka

Phys. Plasmas 8, 2587 (2001); http://dx.doi.org/10.1063/1.1356742 (8 pages) | Cited 83 times

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Partial electrical discharges in a water solution as a function of conductivity have been studied experimentally. Using needle-plate electrodes it has been demonstrated that the discharge evolves in two phases. During the first streamer-like phase, the discharge propagated with a velocity of 106 cm/s, while during the second arc-like phase the length of the discharge remained almost constant although the current still increased. Higher solution conductivity resulted in the generation of shorter channels, in larger discharge current, and in a higher plasma electron density. Degradation of phenol by the discharge has also been demonstrated. A special metallic electrode covered by a thin layer of porous ceramic has been developed and used for generation of a multichannel discharge. At comparable solution conductivity the ceramic-coated electrode produced plasma with very similar parameters as the needle-plate electrode configuration. Generation of strong focused shock waves by the multichannel discharge in a highly conductive solution has also been demonstrated. © 2001 American Institute of Physics.
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52.25.-b Plasma properties
52.35.Tc Shock waves and discontinuities
52.80.Wq Discharge in liquids and solids
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
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