Plasma diagnostics with electric probes

Clements, R. M.

doi:10.1116/1.569453

Cited by 112 publications

(14 citation statements)

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“…Electron number density was determined from the electron temperature and electron saturation current measurements, both of which were obtained from the current-voltage traces by the method in [16], as shown here:…”

Section: A Plasma Parameter Determinationmentioning

confidence: 99%

Langmuir Probe Studies of Magnetic Confinement in an Ion Thruster Discharge Plasma

Sengupta

Goebel

Owens

2009

Journal of Propulsion and Power

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Magnetic confinement studies on a 30-cm-diameter ion thruster were performed to determine the dependence of plasma confinement and uniformity on the ring-cusp magnetic field. Four primary cases were investigated to determine the effects of an additional magnetic cusp, increasing the strength of the highest value closed magnetic contour line, and varying the magnetic field free volume. A laboratory model NASA Solar Electric Propulsion Technology Application Readiness engine was modified to investigate three-and four-ring-cusp geometries. Electrical parameters and langmuir probe sweeps in the discharge chamber were used to measure the performance of each configuration. Increasing the strength of the closed magnetic contour line reduces ion loss to the anode, resulting in a reduction in discharge power for a given beam current. Similarly, increasing the magnetic field free volume in the near-grid region improves plasma uniformity, removing the on-axis current density peak responsible for accelerator grid erosion. The enhanced magnetic circuit geometries investigated resulted in a 20% reduction in discharge loss and discharge current at the TH15 (2.3 kW) throttle point, with similar gains over the full throttle range. The reduction in discharge power and peak current density can significantly increase the total throughout per engine by limiting wear mechanisms that limit thruster life. NomenclatureA p = probe area e = electron charge I sati;e = saturation current (ion, electron) J B = beam current J D = discharge current j i = ion current density k = Boltzmann constant m e = electron mass n e = electron density T e = electron temperature V B = beam voltage V D = discharge voltage V f = floating potential V p = plasma potential " B = discharge loss tot = total efficiency

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Section: A Plasma Parameter Determinationmentioning

confidence: 99%

Langmuir Probe Studies of Magnetic Confinement in an Ion Thruster Discharge Plasma

Sengupta

Goebel

Owens

2009

Journal of Propulsion and Power

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“…Laframboise's theory was used to analyze the Langmuir probe data [25], analyzing the electron current to the probe, I e , in the transition region of the current-voltage (I -V) characteristics (assuming Maxwellian electron distribution [27]).…”

Section: Arc-jet Facility Set-up For On-ground Simulation Of Communicmentioning

confidence: 99%

Plasma-Radiofrequency Interactions Around Atmospheric Re-Entry Vehicles: Modelling and Arc-Jet Simulation

Savino

Paterna²,

Fum³

et al. 2010

TOAEJ

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An aero-thermo-chemical model is developed to simulate the flowfield, including ionization, around atmospheric re-entry configurations, and its interactions with radio-frequency communication signals (e.g. GPS). The model is successfully validated against literature in-flight measurements of the electron number density, and then applied to the re-entry of recently proposed concepts of slender configurations. The advantages of using sharp and slender geometries for re-entry applications, with respect to radio communication problems, are analyzed and discussed. In addition, an experimental test-bed in an arc-jet plasma wind-tunnel has been setup to reproduce on ground the plasmaradiofrequency interaction. The capability to duplicate on-ground the ionization levels encountered during re-entry has been successfully demonstrated. A numerical model of an Argon plasma jet in chemical and thermal non-equilibrium has also been developed, for numerical rebuilding of the experiments. Both electron number densities and electron temperatures have been successfully correlated, demonstrating the ability of arc-jet facilities, integrated with proper numerical tools, to correctly deal with problems of communication attenuation/black-out.

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“…This electron confinement significantly increases the efficiency and, as a result, a magnetron can operate at low pressures (e.g., 1-3 mtorr) and low voltage (e.g., 350 V). Figure 2 shows a cross-sectional view of a typical planar magnetron [4,9,[63][64][65]. Therefore, the erosion of the target is nonuniform.…”

Section: β Magnetron Sputter Sourcesmentioning

confidence: 99%

Sputter Deposition Processes

Parsons

1991

Thin Film Processes

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Plasma diagnostics with electric probes

Cited by 112 publications

References 0 publications

Langmuir Probe Studies of Magnetic Confinement in an Ion Thruster Discharge Plasma

Langmuir Probe Studies of Magnetic Confinement in an Ion Thruster Discharge Plasma

Plasma-Radiofrequency Interactions Around Atmospheric Re-Entry Vehicles: Modelling and Arc-Jet Simulation

Sputter Deposition Processes

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