Electron dynamics and $\gamma$ and $e^{-}{e}^{+}$ production by colliding laser pulses

The dynamics of an electron bunch irradiated by two focused colliding super-intense laser pulses and the resulting $\gamma$ and $e^{-}{e}^{+}$ production are studied. Due to attractors of electron dynamics in a standing wave created by colliding pulses the photon emission and pair production, in general, are more efficient with linearly polarized pulses than with circularly polarized ones. The dependence of the key parameters on the laser intensity and wavelength allows us to identify the conditions for the cascade development and $\gamma e^{-}{e}^{+}$ plasma creation.

Figure 1

Electron density (color scale, $n_e/n_c$) in the $(x,y)$ plane at $T_{max}$, when the laser intensity is maximum in the focal spot, for different laser polarization: (a) CP, (b) LP; (c) LP at $T_{max}+T/4$. Green (magenta) curves for positive (negative) electric field $y$ component.

Figure 2

Electron trajectories in the phase subspace for $T_{max}<t<T_{max}+2T$ for (a, c) CP and (b, d) LP. Color scale represents (a, b) time $t$ in laser periods; (c, d) the electron ${\chi }_e$ parameter.

Figure 3

Parameters ${\chi }_e$ and ${\chi }_{ep}$ for seed (a) and Breit-Wheeler (b) electrons, respectively, in the $(x,y)$ plane at $T_{max}$ for LP.

Figure 4

Energy spectra of seed and Breit-Wheeler electrons (a), and photons (b) at $T_{max}$ for different laser polarization. In (a), the number of B-W electrons for CP multiplied by a factor of ${10}^2$. (c) Electron and photon distribution with respect to ${\chi }_e,{\chi }_{ep},$ and ${\chi }_{\gamma }$ parameters for LP.

Figure 5

Maximum ${\chi }_e, {\chi }_{ep}$, and ${\chi }_{\gamma }$ parameters vs. laser intensity, $I$, and wavelength, $\lambda$, for CP (a, b, c) and LP (d, e, f), respectively.

Figure 6

Angular energy distribution of photons having energy (a) from 1 to 10 MeV, (b) from 10 to 100 MeV and (c) from 100 MeV to 1 GeV. Dash-dotted line for LP, solid for CP. In (c), the number of photons for CP multiplied by a factor of ${10}^2$. The angle $\alpha =0^{\text{o}}$ ($\alpha ={90}^{\text{o}}$) corresponds to the $y$ axis ($x$ axis) direction.