Application of a quadruple probe technique to MPD thruster plume measurements

Burton, Rodney L.; Delmedico, S.; Andrews, J.

doi:10.2514/3.23688

Cited by 33 publications

(10 citation statements)

References 13 publications

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“…35 In our experimental results, the fact that γ lies in the range of 1.2-1.4 means the electrons are not separated totally from each other like two neutral rigid balls but influenced with other charged particles by the force field, and this specific value of γ relates tightly with the plasma parameters such as the electron temperature and velocity.…”

Section: E Electron Temperatures Derived From the "Poly-tropic Law" mentioning

confidence: 89%

Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

Zhang

Tang

Kong

et al. 2015

Review of Scientific Instruments

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Published electron temperature profiles of the beam plasma from ion thrusters reveal many divergences both in magnitude and radial variation. In order to know exactly the radial distributions of electron temperature and understand the beam plasma characteristics, we applied five different experimental approaches to measure the spatial profiles of electron temperature and compared the agreement and disagreement of the electron temperature profiles obtained from these techniques. Experimental results show that the triple Langmuir probe and adiabatic poly-tropic law methods could provide more accurate space-resolved electron temperature of the beam plasma than other techniques. Radial electron temperature profiles indicate that the electrons in the beam plasma are non-isothermal, which is supported by a radial decrease (∼2 eV) of electron temperature as the plume plasma expands outward. Therefore, the adiabatic "poly-tropic law" is more appropriate than the isothermal "barometric law" to be used in electron temperature calculations. Moreover, the calculation results show that the electron temperature profiles derived from the "poly-tropic law" are in better agreement with the experimental data when the specific heat ratio (γ) lies in the range of 1.2-1.4 instead of 5/3.

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Section: E Electron Temperatures Derived From the "Poly-tropic Law" mentioning

confidence: 89%

Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

Zhang

Tang

Kong

et al. 2015

Review of Scientific Instruments

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“…Both cylindrical triple probes 15,16 and guarded Faraday probes 17 were used to measure ion flux throughout the experiment via probe arrays, and a two-dimensional ͑2D͒ scanning stage. Two designs of Langmuir triple probes were used, one a smaller scanning probe with cylindrical stainless steel conductors with radius of 0.45 mm and height of 5 mm, and the other an array of larger cylindrical conductors with radius of 1.2 mm and height of 6 mm.…”

Section: A Plasma Diagnosticsmentioning

confidence: 99%

Plume detachment from a magnetic nozzle

et al. 2009

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High-powered electric propulsion thrusters utilizing a magnetized plasma require that plasma exhaust detach from the applied magnetic field in order to produce thrust. This paper presents experimental results demonstrating that a sufficiently energetic and flowing plasma can indeed detach from a magnetic nozzle. Microwave interferometer and probe measurements provide plume density, electron temperature, and ion flux measurements in the nozzle region. Measurements of ion flux show a low-beta plasma plume which follows applied magnetic field lines until the plasma kinetic pressure reaches the magnetic pressure and a high-beta plume expanding ballistically afterward. Several magnetic configurations were tested including a reversed field nozzle configuration. Despite the dramatic change in magnetic field profile, the reversed field configuration yielded little measurable change in plume trajectory, demonstrating the plume is detached. Numerical simulations yield density profiles in agreement with the experimental results.

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“…Signal lead wires then carry the probe signal to the processing circuitry including voltage stepup and isolation transformers and passive integrators. 10 In conjunction with the magnetic probe array, a movable quadruple Langmuir probe 8,11 was employed to measure the floating potential, electron temperature, electron density, and plasma velocity simultaneously. This Langmuir probe was positioned to the same axial location as the magnetic probe array prior to each discharge in order to obtain a complete set of data for each axial position within the annular flow channel.…”

Section: Experimental Facility and Diagnosticsmentioning

confidence: 99%

Determination of microturbulence enhanced electron collisionality in magnetized coaxial accelerator channels by direct magnetic field measurement

1997

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A miniature magnetic probe array, consisting of 10 spatially separated coils, has been used to obtain profile information on the time varying magnetic field within the 2.54 cm wide flow channel of the coaxial plasma source experiment (CPS-1) [R. M. Mayo et al., Plasma Sources Sci. Technol. 4, 47 (1995)]. The magnetic field data have been used, together with a resistive, Hall magnetohydrodynamic (MHD) model of applied field distortion by the flowing plasma, to obtain estimates of the microturbulent enhancement to electron collisionality within the CPS-1 flow channel. These measurements provide direct experimental evidence of anomalous electron collisionality, a previously predicted effect in these devices. The anomaly parameter, a=νan/νcl, determined both from the distortion of contours of constant magnetic flux, and from local Bθ and Bz measurements scales with the classical electron magnetization parameter (Ωcl=ωce/νecl), indicating that collisionality plays a strong role in determining the level of anomalous transport in the plasma. When this anomaly parameter scaling is cast in terms of the ratio νecl/ωlh, it is found that the resistivity enhancement scales with νecl/ωlh, and becomes significant at νecl/ωlh⩽1, suggesting that a lower hybrid drift instability may be the responsible mechanism for enhanced transport.

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Application of a quadruple probe technique to MPD thruster plume measurements

Cited by 33 publications

References 13 publications

Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

Plume detachment from a magnetic nozzle

Determination of microturbulence enhanced electron collisionality in magnetized coaxial accelerator channels by direct magnetic field measurement

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