Dynamically assisted pair production enhancement by combined multiple potentials

We propose a new Sauter-like field model with combinatorial multiple potentials consisting of a deep slow-varying and some shallow fast-varying potentials. The dynamically assisted Sauter-Schwinger effect on the pair production is found by using the computational quantum field theory. The enhanced pair production is found to be significant at about one order increasing for multiple potentials rather than single potential. In case of dominated by Schwinger mechanism, the obvious time effect leads to electrons concentrating at the two edges of the potential, meanwhile, the momentum locates at the zero nearby. In contrary, however, for the multiphoton processes, the pair generation makes the electrons distributing outside the potential and the momentum appearing multiple peaks far away from zero and evenly evolving toward a step-like structure. An interesting finding is that the particles of pair produced in the alternating potential has a quasi-monoenergetic structure compared to the oscillating potential well or/and potential barrier, which is helpful to achieve the high quality positron source.