“…When selecting cylindrical coordinate system (r, φ, z), taking r axis as u axis and considering z-axis polarization, these equations are reduced into a model of cylindrical waves which are studied in Refs. [5,6,[19][20][21][22][23][24][25][26][27][28]. For convenience, we introduce the dimensionless variables ρ = u/u 0 , τ = ct/u 0 , E = E v /(N/C), and H = µ 0 cH w /(N/C), where u 0 is a constant associated with the characteristic spatial scale, c is the speed of light in vacuum, and (N/C) is the unit of electric field strength in the international system of units.…”