ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Anode sheaths are explored in detail for collisional, identical-specie-temperature plasmas where sheath dimensions are in the micron range. The selected approach involves postulation of a specific electric field distribution with three shape factors. Previous research using this approach is verified and expanded upon using greater parameter ranges. z, a dimensionless quantity specifying plasma composition and condition, groups diverse plasmas into families exhibiting similar sheath characteristics. η, a nondimensional ratio of electrical energy to thermal energy in the sheath, allows temperature effects to be studied. This investigation focuses on plasma families that span a z range of 1.1729 to 2.1493 at η values defined by discrete plasma temperatures of 6000, 3000, and 300 K. Results indicate that at the lower temperatures, charge production in the outer sheath is somewhat generic to the electric field distribution, and that the sheaths themselves are nearly unaffected by substantial changes in temperature (i.e., η). Conversely, sheath density and extent are shown to vary significantly for differing z values. Equations governing cylindrical anodes generate sheaths that are virtually identical to corresponding planar cases. It is shown that only those anodes whose radii are comparable to the plasma's characteristic radius (γ) must be treated with the cylindrical formulation; low- and moderate-pressure plasmas would require micron-diameter anodes to be thus affected. Finally, an analytical approach shown yields solutions that confirm the numerical results, and offers an algebraic approximation for high-η plasmas.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.353927
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