摘要： Numerical simulations are important when assessing the many characteristics of field emission related phenomena. In this work, we analyze the fractional change of the apex-Field Enhancement Factor (FEF), ??, from a single emitter, with apex-FEF ??1, and a pair, with apex-FEF ??2. We show, based on finite element technique, that the functional dependence ??(??) (?? corresponding to the distance between the axis of the emitters) obeys a recently proposed power law decay [1], at sufficient large distances in the limit of infinite domain size, which is not observed by using a long time established exponential decay [2] or a more sophisticated fitting formula proposed recently by Harris et al. [3]. This inverse-third power law functional dependence is respected for various systems like infinity arrays and small clusters of emitters with different shapes. Thus, ??? ～ ?????, with ?? = 3, is suggested to be a universal signature of the charge-blunting (CB) effect in small clusters or arrays, at sufficient large distances between emitters with any shape. These results improve the physical understanding of the field electron emission theory to accurately characterize emitters in small clusters or arrays.