Two-dimensional momentum distribution of positrons in super-chirped laser field in the vacuum
In this study,the two-dimensional momentum spectra of electron-positron pairs produced in vacuum under different forms of a strong chirped laser field and the particle number density under different chirped coefficients are investigated using the quantum dynamic equations.The two-dimensional momentum spectrum of positrons created in vacuum indicates an obvious interference distribution effect after the laser frequency is chirped in various forms.Moreover,the two-dimensional momentum spectrum gradually tends to be isotropic,i.e.,exhibits a normal circular distribution,which is a remarkable characteristic of the chirped field reflected in this spectrum.In addition,the reason for the interference effect can be qualitatively understood by analyzing the structure of turning points.Investigation of the number density of particles shows that it is very sensitive to the chirp coefficient.Moreover,the number density shows an obvious periodic distribution and enhancement with a change in the chirp parameter.This observation provides a new method for increasing the production of electron-positron pairs in future experiments.
strong chirped fieldelectron-positron pairstwo-dimensional momentum distribution
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