Effective collision frequency of electrons in noble gases

Baille, P.; Chang, Jen‐Shih; Claude, A; Hobson, R. M.; Ogram, G.L.; Yau, A. W.

doi:10.1088/0022-3700/14/9/013

Cited by 82 publications

(24 citation statements)

References 29 publications

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“…However, as described previously, determining an effective collision frequency is not entirely straightforward. Effective collision frequency was determined from a model presented by Baille et al 18 that gives collision frequency as a function of electron temperature (or velocity) and number density since the momentum-transfer collision frequency has been found to vary greatly 18 with electron energies in the range of 0.1 to 5 eV. Therefore, a true representative electron velocity is needed in order to calculate an accurate collision frequency.…”

Section: Results and Analysismentioning

confidence: 99%

“…Since mobility is governed by electron-neutral collisions and since the electron-neutral collision frequency scales with electron velocity, it is important to determine which component of electron motion dictates the collision frequency. The characteristic electron trap motions are used in determining an effective momentum transfer collision frequency, as collision frequency can vary greatly with electron temperatures below 5 electron volts 18 . Although in general the characteristic frequencies scale as ce > B > within the operating regimes presented, the characteristic velocities corresponding to each of these frequencies (u , u eB and u e , respectively) do not necessarily scale as simply.…”

Section: B Electron Motions Within Confinement Volumementioning

confidence: 99%

“…At this point, the characteristic velocities scale as u e > u eB > u . Based on an effective collision frequency model for krypton given by Baille 18 , the effective collision frequency is on the order of 10 6 s -1 for operating pressures on the order of 5x10 -6 torr. At the highest B fields investigated u e drops by an order of magnitude which changes the scaling to u eB > u e > u .…”

Section: B Electron Motions Within Confinement Volumementioning

confidence: 99%

See 2 more Smart Citations

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Fossum

King

Makela

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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An electron trapping apparatus was constructed in order to study electron dynamics in the defining electric and magnetic fields of a Hall-effect thruster. The approach presented here decouples the cross-field mobility from plasma effects by conducting measurements on a pure electron plasma in a highly controlled environment. Dielectric walls are removed completely eliminating all wall effects; thus, electrons are confined solely by a radial magnetic field and a crossed, independently-controlled, axial electric field that induces the closed-drift azimuthal Hall current. Electron trajectories and cross-field mobility were examined in response to electric and magnetic field strength and background neutral density. Without wall effects or neutral plasma effects mobility is presumed to follow the classical mobility model. In the present research, measurement techniques are investigated, and results are verified against the classical model. Preliminary findings suggest that that the apparatus and techniques used will be valid for mobility studies in more complex field environments. Nomenclature

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Section: Results and Analysismentioning

confidence: 99%

Section: B Electron Motions Within Confinement Volumementioning

confidence: 99%

Section: B Electron Motions Within Confinement Volumementioning

confidence: 99%

See 1 more Smart Citation

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Fossum

King

Makela

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

View full text Add to dashboard Cite

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“…For electron-neutral collision frequency empirical formula from Ref. 19 gives en Ϸ 5.6ϫ 10 4 s −1 , which is two orders of magnitude lower than the collision frequency in the model. For electron-ion collision frequency the estimate 20 is ei Ϸ 5.8ϫ 10 6 s −1 , which is very close to the value = 0.007⍀ ce Ϸ 6.2 ϫ 10 6 s −1 obtained from EMHD model for the best match with the experimental measurements.…”

Section: Comparison Of Emhd Model and Experimentsmentioning

confidence: 76%

Generation of whistler waves by a rotating magnetic field source

Karavaev¹,

Gumerov²,

Papadopoulos³

et al. 2010

Physics of Plasmas

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The paper discusses the generation of polarized whistler waves radiated from a rotating magnetic field source created via a novel phased orthogonal two loop antenna. The results of linear three-dimensional electron magnetohydrodynamics simulations along with experiments on the generation whistler waves by the rotating magnetic field source performed in the large plasma device are presented. Comparison of the experimental results with the simulations and linear wave properties shows good agreement. The whistler wave dispersion relation with nonzero transverse wave number and the wave structure generated by the rotating magnetic field source are also discussed. The phase velocity of the whistler waves was found to be in good agreement with the theoretical dispersion relation. The exponential decay rate of the whistler wave propagating along the ambient magnetic field is determined by Coulomb collisions. In collisionless case the rotating magnetic field source was found to be a very efficient radiation source for transferring energy along the ambient magnetic field lines.

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“…In weakly ionized plasma, collision frequency is a function of physical parameters such as electron temperature and gas species [1], [32]. Thus, for the sake of generality, the values of the model elements are plotted versus electromagnetic parameters instead of physical parameters.…”

Section: Resultsmentioning

confidence: 99%

Equivalent Circuit Model for Frequency-Selective Surfaces Embedded Within a Thick Plasma Layer

Joozdani

Amirhosseini

Abdolali

2015

IEEE Trans. Plasma Sci.

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In this paper, an equivalent circuit model for a frequency-selective surface (FSS) embedded in a thick plasma layer is introduced. The plasma layer is a lossy and dispersive medium, and therefore, the equivalent model is not purely imaginary and consists of resistive elements as well as inductance and capacitance elements. First, a square patch FSS is simulated in a wide frequency range from 1 to 25 GHz by a full-wave electromagnetic software, and then all the circuit elements are calculated by genetic algorithm optimization to achieve reflection coefficient similar to the one obtained by simulation. It is shown that this model can mimic the simulated behavior with good approximation. Then values of different elements of the model through practical variations of cold plasma parameters are plotted, and the effects of electron density and collision frequency are investigated on circuit elements.

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Effective collision frequency of electrons in noble gases

Cited by 82 publications

References 29 publications

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Mobility Studies of a Pure Electron Plasma in Hall Thruster Fields

Generation of whistler waves by a rotating magnetic field source

Equivalent Circuit Model for Frequency-Selective Surfaces Embedded Within a Thick Plasma Layer

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