Amplitude-controlled electron correlation in nonsequential double ionization of argon

Abstract The effect of the relative amplitude on the nonsequential double ionization (NSDI) for Ar in a parallel-polarized two-color laser field is investigated by using the classical ensemble method. It is found that the NSDI yield of Ar varies with the relative amplitude. As the relative amplitude increases, the correlated electron momentum distribution gradually evolves from a finger-like structure to an arc-like structure, and ultimately exhibits a cross-shaped structure. The underlying reason is that as the relative amplitude increases, the returning electron acquires higher energy, enabling it to traverse the effective region of the parent ion rapidly, which leads to the energy transferred to the second electron decreases.