Self-affine and mound roughness effects on the double-layer charge capacitance

In this article, we investigate the influence of self-affine and mound roughness on the charge capacitance of double layers. The influence of self-affine roughness is more significant for small roughness exponents (H,0.5) and/or large roughness ratios w/j, as well as small charge and counter charge separations in electrolyte plasma as described by the Debye length lD(,j). On the
other hand, mound roughness has a more complex influence on the charge capacitance, when the system correlation length z is larger than the average mound separation l. In this case, the charge capacitance oscillates as a function of the parameters l and z before it approaches the Gouy– Chapman @G. Gouy, J. Phys. ~Paris! 9, 457 ~1910!; D. L. Chapman, Philos. Mag. 25, 475 ~1913!# asymptotic limit for smooth interfaces. Furthermore, the oscillation magnitude is larger for relatively small Debye lengths lD(,z,l).