Using the Dirac-Heisenberg-Wigner (DHW) formalism, effects of asymmetric pulse shape on the generation of electron-positron pairs in three typical polarized fields, i.e., the linear, middle elliptical and circular ones, are investigated. Two kinds of asymmetries for the falling pulse length, one is compressed and the other is elongated, are studied. It is found that the interference effect disappears with the compression of the pulse length, and finally the peak value of the momentum spectrum is concentrated in the center of the momentum space. For the opposite situation by extending the falling pulse length, a multi-ring structure without interference appears in the momentum spectrum. Research results exhibit that the momentum spectrum is very sensitive to the asymmetry of the pulse as well as to the polarization of the fields. It is also found that the number density of electron-positron pairs under different polarizations is sensitive to the asymmetry of electric field. For the compressed falling pulse, the number density can be enhanced significantly over $2$ orders of magnitude. These results could be useful in planning high power or/and high-intensity laser experiments.
Olugh Obulkasim, Li Ziliang, Xie Baisong. Asymmetric pulse effects on pair production in polarized electric fields[J]. High Power Laser Science and Engineering, , (): .
