Exact Solution for the Generalized Bohm Criterion in a Two-Ion-Species Plasma

Lee, Dongsoo; Öksüz, Lütfi; Hershkowitz, N.

doi:10.1103/physrevlett.99.155004

Cited by 41 publications

(50 citation statements)

References 25 publications

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“…Ion acceleration at the plasma boundary is established by a weak electric field in the presheath, 1,2 which accelerates ions to the Bohm velocity at the sheath edge, 3-7 followed by a strong electric field in the plasma sheath. It bears repeating that this is in general not true for plasmas with multiple positive ion species, 5,6 and that only for two component plasmas ͑one positive and one negative species for which M + ӷ M − ͒ does the usual Bohm criterion apply. The generalized Bohm criterion applies 8 in the case of multiple positive ion species, and is satisfied by a continuum of possible sheath edge ion speeds, for each ion species.…”

Section: Experimental Studies Of Transverse Metastable Ion Velocity Dmentioning

confidence: 89%

Experimental studies of transverse metastable ion velocity distribution functions in the presheath of a weakly collisional argon plasma

2008

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Laser-induced fluorescence measurements of the transverse metastable ion velocity distribution function near a negatively biased plate in a low temperature (Te<1eV), low pressure (p0<1mTorr) dc multi-dipole argon discharge plasma have been made with a diode laser. The metastable argon ions in the 3s23p4(P3)3d4F7∕2 state are found to be characterized by a Maxwellian temperature transverse to the direction normal to the plate. For a neutral pressure of 0.3mTorr, the transverse temperature increases along the presheath from 0.026eV in the bulk plasma to 0.058eV at the presheath sheath boundary.

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Section: Experimental Studies Of Transverse Metastable Ion Velocity Dmentioning

confidence: 89%

Experimental studies of transverse metastable ion velocity distribution functions in the presheath of a weakly collisional argon plasma

2008

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“…In a multiple ion low pressure plasma with comparable ion densities n i,k , each species, marked with an index k, enters the sheath with the bulk ion sound velocity [21] v B = e 0 V e n e,0 k…”

Section: Description Of the Energy Fluxes Between Plasma And Particlementioning

confidence: 99%

Microparticles as Plasma Diagnostic Tools

Maurer

Schneider

Wolter

et al. 2011

Contrib. Plasma Phys.

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An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of microparticles with the surrounding plasma for diagnostic purposes. Local electric fields can be determined from the behavior of particles in the plasma, i.e. particles may serve as electrostatic probes. From particle trajectories, also the determination of momentum flux in beams is possible, and the particles serve as force probes. Recently, temperature sensitive features of particular phosphors were utilized for measuring the surface temperature of microparticles confined in the sheath of a rf plasma. The experiments were performed under variation of gas pressure and rf power of the process plasma and offer a promising approach for the improvement of process plasmas and the understanding of plasma-particle interaction.

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“…In an unmagnetized case, the solutions with valid entry velocity combinations of various ion species constituting this flow setup are obtained by employing the generalized Bohm criterion, 2 which admits distinct flow velocity values for individual species, in conjunction with a generalized dispersion relation of the multiple ion species plasma, and then making an assumption that the plasma parameters change negligibly across an accelerating presheath formed between a quiescent bulk and the electrostatic sheath edge. 3 In a magnetized multiple ion species plasma, however, an equivalent of the generalized Bohm criterion is necessary to ascertain the stable flow velocity combinations that would enable a stable plasma sheath to form.…”

Section: Introductionmentioning

confidence: 99%

Valid flow combinations for stable sheath in a magnetized multiple ion species plasma

Sharma

Kaw

2012

Physics of Plasmas

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Theoretical study is done of the entry criterion for the plasma flow into the electrostatic boundary layer, or sheath, forming in a magnetized multiple ion species plasma. Finding valid entry velocity combinations in a magnetized set up requires a magnetized equivalent of the generalized Bohm criterion. A magnetized generalized entry criterion is obtained with the scale length distribution in a region of validity for the stable solutions. The analysis finds that the valid entry flow velocity combinations with distinct values of individual ion species can correspond to a unique system phase velocity. Magnetization effects govern the region of validity whose boundaries collapse to the unmagnetized sheath criterion in the limit of normal incidence, independent of the strength of the magnetic field. Considerably smaller entry velocities, in comparison to the unmagnetized system sound velocity, are recovered for the species in appropriate regime of magnetization in the cases of oblique incidences. V C 2012 American Institute of Physics.

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Exact Solution for the Generalized Bohm Criterion in a Two-Ion-Species Plasma

Cited by 41 publications

References 25 publications

Experimental studies of transverse metastable ion velocity distribution functions in the presheath of a weakly collisional argon plasma

Experimental studies of transverse metastable ion velocity distribution functions in the presheath of a weakly collisional argon plasma

Microparticles as Plasma Diagnostic Tools

Valid flow combinations for stable sheath in a magnetized multiple ion species plasma

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