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15 Jul 2004

Volume 96, Issue 2, pp. 951-1278

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The kinetic energy of carbon ions in vacuum arc plasmas: A comparison of measuring techniques

André Anders and George Yu. Yushkov

J. Appl. Phys. 96, 970 (2004); http://dx.doi.org/10.1063/1.1762712 (5 pages) | Cited 5 times

Online Publication Date: 30 June 2004

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Ions in cathodic arc plasmas have high velocities attained by acceleration at cathode spots. Among other techniques, two time-of-flight setups had previously been used to determine ion velocities. These measurements showed significant discrepancies especially for some light cathode materials like carbon. To reconcile the differences, a thorough investigation was conducted using carbon as the cathode material. It is shown that systematic errors occur when the ion source time-of-flight system is not operated near perveance-matching conditions. The extracted ion beam is not parallel but divergent, and the Faraday cup detector measures only a fraction of the beam. In contrast, plasma source experiments without ion extraction are free of such distortions. In the absence of an external magnetic field, the average carbon ion energy has been determined to be in the range 18.5–20.5 eV for arc currents in the range 100–600 A, in agreement with previous plasma source measurements and other literature data. © 2004 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum

Characterization of ablated species in laser-induced plasma plume

Hideki Furusawa, Tetsuo Sakka, and Yukio H. Ogata

J. Appl. Phys. 96, 975 (2004); http://dx.doi.org/10.1063/1.1759397 (8 pages) | Cited 21 times

Online Publication Date: 30 June 2004

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Plasma electron density and atomic population densities in the plasma plume produced by a laser ablation of aluminum metal were determined in various ambient gases at relatively high pressures. The method is based on the fit of a spectral line profile of Al(I) 2P∘-2S emission to the theoretical spectrum obtained by one-dimensional radiative transfer calculation. The electron density was higher for a higher ambient gas pressure, suggesting the confinement of the plume by an ambient gas. The electron density also depends on the type of ambient gases, i.e., it increased in the order He<CH4<N2<CF4, while the atomic population density is almost independent of the type of ambient species and pressure. The population densities of the upper and lower levels of the transition were compared, and the ratio between their spatial distribution widths was calculated. These results provide valuable information regarding the confinement of the plume by the ambient gas and give insight into the time evolution of the plume. © 2004 American Institute of Physics.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.38.Mf Laser ablation
52.25.Fi Transport properties
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.Jm Ionization of plasmas

Influence of design and operation parameters on Hall thruster performances

E. Ahedo and D. Escobar

J. Appl. Phys. 96, 983 (2004); http://dx.doi.org/10.1063/1.1759790 (10 pages) | Cited 11 times

Online Publication Date: 30 June 2004

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A stationary, macroscopic model [E. Ahedo, J. Gallardo, and M. Martínez-Sánchez, Phys. Plasmas 10, 3397 (2003)] is used to carry out parametric investigations on the effects of (i) the discharge voltage, (ii) the gas flow rate, (iii) the axial gradient of the magnetic field, and (iv) the chamber length on the Hall thruster performances and the axial structure of the plasma discharge. The high-thrust and high-specific-impulse modes for dual-mode thrusters are compared too. The results of the simulations agree well with the main tendencies observed in different experiments. The interaction among the several physical phenomena is discussed and useful scaling laws are proposed. Special attention is paid to understand (i) the adjustment of the magnetic field strength with the discharge voltage for optimum operation, (ii) the effect of the magnetic field shape, (iii) the dimensions of the different regions of the discharge, and (iv) the parameter trends needed to increment the propulsive and ionization efficiencies (the product of which determines the thrust efficiency). © 2004 American Institute of Physics.
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52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
52.65.Kj Magnetohydrodynamic and fluid equation
52.25.Jm Ionization of plasmas
52.75.Di Ion and plasma propulsion

Characteristics of plasma display panel with ridged dielectric and hollow gap between sustain electrodes

Mun-Ho Nam, Jung-Min Kim, Sie-Young Choi, Seung-Hyun Son, and Young-Mo Kim

J. Appl. Phys. 96, 993 (2004); http://dx.doi.org/10.1063/1.1756694 (4 pages) | Cited 11 times

Online Publication Date: 30 June 2004

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This article presents a front panel structure for an alternating current plasma display panel (AC-PDP) based on a ridged transparent dielectric layer and long hollow gap between the sustain electrodes. The suggested structure can reduce a firing voltage and sustain voltage than a conventional AC-PDP due to a strong electric field between the sustain electrodes. Experiments were conducted with various Xe contents from 10% to 50% at a gas pressure of 450 Torr, and the results confirmed that the ridged dielectric structure reduce the firing and sustain voltages by about 74 and 79 V at 10% Xe content than a conventional structure with 10% Xe content, respectively. Also, the proposed structure improve the luminous efficiency and luminance by about 50.9% and 33%, respectively, with a 50% Xe content when compared to a conventional structure with a 10% Xe content at a similar driving voltage. © 2004 American Institute of Physics.
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52.75.-d Plasma devices
85.60.Pg Display systems
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