Space charge effect of time-dependent emission current excited from ultrafast laser

Classical Child-Langmuir law(CL law) analytically demonstrates maximum steady current density transported. Á. Valfells et al. in 2002 presented its analytic modification under short pulse case. However, both above have not touched time-dependence problem. In this paper, an iterative calculation method to consider time-dependent short-pulse of electron flow is developed, confirmed by particle-in-cell(PIC) simulation. Our calculation shows that for ultrahigh laser field amplitude, space charge effect becomes notable and electric DC field can be an efficient parameter to tune the space-charge limit.