Fig. 5: Transition of diffusion regimes in spatial afterglow.
From: Charge decay in the spatial afterglow of plasmas and its impact on diffusion regimes
a Illustration of the growth of the Debye length (decrease in χ) as charge decays in the spatial afterglow. b Debye length, λD, as a function of the dimensionless distance in the spatial afterglow, ξ, at 75 and 760 Torr. c Normalized diffusivity, Dapp/Di, as a function of dimensionless distance in the spatial afterglow, ξ, for ions (solid lines) and electrons (dashed lines) at 75 and 760 Torr. d Critical axial distance in the spatial afterglow, ξcrit, for transition from ambipolar to free diffusion as a function of pressure (solid red line). ξcrit for the limiting cases of diffusion- and recombination-dominated charge density decay (dotted and dashed lines, respectively) are also shown for comparison (Supplementary Note 9). In all cases, the following parameters were kept constant: Te = 1.5 eV, Tg = 300 K, Q = 1000 sccm, and Λ = 1.91 mm. In addition, np was extrapolated from experimental measurements (Fig. 2a).
