The summed unpolarized DCS versus the polar angle of the polarization vector of the field at ε 0 = 5.14 × 10 7 V · cm − 1 , (a) θ = 1 ° , or (b) θ = 90 ° , and ϕ = 1 ° . The solid line shows the DCS of the laser-free case, and the dashed one for that of the laser-assisted case. Impact energy of electron is the same as that in Fig. 1.